Effect of various light curing times on the elution of composite components.

PubMed

Högg, Christof; Maier, Moritz; Dettinger-Maier, Katherina; He, Xiuli; Rothmund, Lena; Kehe, Kai; Hickel, Reinhard; Reichl, Franz-Xaver

2016-11-01

Polymerization of resin-based composites (RBCs) is incomplete. The aim of the present study was to determine whether a longer curing time than recommended by the manufacturer influences the amount of released composite components of RBCs. The composites Clearfil AP-X and els extra low shrinkage were polymerized for six different curing times: 4, 10, 20, 40, 100, and 200 s. Light curing time recommended by the manufacturer for both composites is 20 s. Subsequently, samples were eluted in methanol and water for 1, 3, and 7 days and analyzed by gas chromatography/mass spectrometry (GC/MS). For Clearfil AP-X ethylene glycol dimethacrylate (EGDMA), diethylene glycol dimethacrylate (DEGDMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxy-4-methoxybenzophenone (HMBP), camphorquinone (CQ) and 2,6-di-tert-butyl-4-methylphenol (BHT) were detected in methanol. In the aqueous eluate, only TEGDMA was detected. In els extra low shrinkage, HMBP, BHT, and CQ were detected in methanol. Increasing the curing time compared to recommendation of the manufacturer reduces the release of most composite components. This could result in less exposure to human due to these substances. Methacrylates are classified as potential allergens. An increasing number of dentists and patients show allergic reaction to methacrylates. Therefore, a reduced elution of composite components is an advantage.

Volatile methacrylates in dental practices.

PubMed

Marquardt, Wolfgang; Seiss, Mario; Hickel, Reinhard; Reichl, Franz X

2009-04-01

In recent years, an increase of occupational respiratory diseases, such as asthma caused by methacrylates, has been observed in dental personnel. In this study, the exposure of dental personnel to various volatile methacrylates was investigated. The air levels of methacrylates were measured during filling treatment while bonding agents were used in 4 dental practices in Munich, Germany. Short-term air sampling (15 min) was performed using solid phase microextraction (SPME). The SPME fibers were coated with carbowax/divinyl benzene to enrich the analytes. For analysis, the analytes were thermically desorbed from the fiber and subsequently analyzed directly by gas chromatography/mass spectrometry. The methacrylates methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA), and triethylene glycol dimethacrylate (TEG-DMA) were identified in the air of dental practices. The exposure levels of the four methacrylates varied during the filling treatments. The maximum concentrations found were 0.4 mg/m3 for MMA, 45 microg/m3 for HEMA, 13 microg/m3 for EGDMA, and 45 microg/m3 for TEG-DMA. The detection of TEG-DMA correlated with the application of bonding agents during performance of dental fillings. Exposure levels of different methacrylates were observed at all investigated dental practices. The maximum levels of MMA measured in this study were at least 200 times lower than the toxicologically relevant maximum allowable concentrations defined in various countries. Nevertheless, the exposure levels of methacrylates should be kept as low as possible due to the allergenic potential of some methacrylates.

Structure/property relationships in methacrylate/dimethacrylate polymers for dental applications

NASA Astrophysics Data System (ADS)

Mehlem, Jeremy John

Since its invention Bis-GMA or one of its analogs has been the main component of the polymer portion of composites for dental restorations. The need for dilution of Bis-GMA and its analogs to optimize its properties has long been recognized. Bis-GMA is a highly viscous monomer. This high viscosity leads to early vitrification, which limits conversion during cure. This viscosity also limits filler loading. Vitrification at low conversions leads to heterogeneous systems composed of low and high cross-link density phases. The low cross-link density phases behave as defects in the system; therefore, if the amount of low cross-link density phases in the system can be reduced and a more uniform network structure can be achieved, then the mechanical properties of the resin can be improved. Since the increase in viscosity during cure causes vitrification, it is logical that a system with a low initial viscosity will delay the onset of vitrification. Reactive diluents such as triethylene glycol dimethacrylate (TEGDMA) are effective at lower levels. However, large amounts negatively affect matrix properties by increasing polymerization shrinkage and water sorption. Shrinkage has been cited as one of the main deficiencies in dental composites. The goal of this project is to improve upon standard viscosity modifying comonomers such as triethylene glycol dimethacrylate. The comonomers that were explored were phenyloxyethyl methacrylate, cyclohexyl methacrylate, and tert-butylcylcohexyl methacrylate. Multicomponent systems based on analogs of ethylene glycol dimethacrylates with different length ethyl glycol chains were also examined. The substitution of monomethacrylates for TEGDMA as a comonomer resulted in enhanced or negligible affects on the mechanical properties of Bis-MEPP based polymer systems while reducing polymerization shrinkage. 129Xenon NMR and TappingMode(TM) AFM were used to characterize the heterogeneity of dimethacrylates systems during their cure cycle as well as in their final state. Using these methods the size of the high and low cross-link density phase was examined and determined to be on the order of 50--150 nanometers. Model compounds based on phenylethyl methacrylate were formulated to determine how of nadic methyl anhydride and maleic anhydride incorporate into dimethacrylate resin systems.

Effect of low-shrinkage monomers on the physicochemical properties of experimental composite resin

PubMed Central

He, Jingwei; Garoushi, Sufyan; Vallittu, Pekka K.; Lassila, Lippo

2018-01-01

Abstract This study was conducted to determine whether novel experimental low-shrinkage dimethacrylate co-monomers could provide low polymerization shrinkage composites without sacrifice to degree of conversion, and mechanical properties of the composites. Experimental composites were prepared by mixing 28.6 wt% of bisphenol-A-glycidyl dimethacrylate based resin matrix (bis-GMA) with various weight-fractions of co-monomers; tricyclo decanedimethanol dacrylate (SR833s) and isobornyl acrylate (IBOA) to 71.4 wt% of particulate-fillers. A composite based on bis-GMA/TEGDMA (triethylene glycol dimethacrylate) was used as a control. Fracture toughness and flexural strength were determined for each experimental material following international standards. Degree of monomer-conversion (DC%) was determined by FTIR spectrometry. The volumetric shrinkage in percent was calculated as a buoyancy change in distilled water by means of the Archimedes’ principle. Polymerization shrinkage-strain and -stress of the specimens were measured using the strain-gage technique and tensilometer, respectively with respect to time. Statistical analysis revealed that control group had the highest double-bond conversion (p < .05) among the experimental resins tested. All of the experimental composite resins had comparable flexural strength, modulus, and fracture toughness (p > .05). Volumetric shrinkage and shrinkage stress decreased with increasing IBOA concentration. Replacing TEGDMA with SR833s and IBOA can decrease the volumetric shrinkage, shrinkage strain, and shrinkage stress of composite resins without affecting the mechanical properties. However, the degree of conversion was also decreased. PMID:29536025

Effect of low-shrinkage monomers on the physicochemical properties of experimental composite resin.

PubMed

He, Jingwei; Garoushi, Sufyan; Vallittu, Pekka K; Lassila, Lippo

2018-01-01

This study was conducted to determine whether novel experimental low-shrinkage dimethacrylate co-monomers could provide low polymerization shrinkage composites without sacrifice to degree of conversion, and mechanical properties of the composites. Experimental composites were prepared by mixing 28.6 wt% of bisphenol-A-glycidyl dimethacrylate based resin matrix ( bis -GMA) with various weight-fractions of co-monomers; tricyclo decanedimethanol dacrylate (SR833s) and isobornyl acrylate (IBOA) to 71.4 wt% of particulate-fillers. A composite based on bis -GMA/TEGDMA (triethylene glycol dimethacrylate) was used as a control. Fracture toughness and flexural strength were determined for each experimental material following international standards. Degree of monomer-conversion (DC%) was determined by FTIR spectrometry. The volumetric shrinkage in percent was calculated as a buoyancy change in distilled water by means of the Archimedes' principle. Polymerization shrinkage-strain and -stress of the specimens were measured using the strain-gage technique and tensilometer, respectively with respect to time. Statistical analysis revealed that control group had the highest double-bond conversion ( p  < .05) among the experimental resins tested. All of the experimental composite resins had comparable flexural strength, modulus, and fracture toughness ( p  > .05). Volumetric shrinkage and shrinkage stress decreased with increasing IBOA concentration. Replacing TEGDMA with SR833s and IBOA can decrease the volumetric shrinkage, shrinkage strain, and shrinkage stress of composite resins without affecting the mechanical properties. However, the degree of conversion was also decreased.

Residual monomers and degree of conversion of partially bioresorbable fiber-reinforced composite.

PubMed

Väkiparta, Marju; Puska, Mervi; Vallittu, Pekka K

2006-01-01

The aim of this study was to evaluate the total quantity of residual monomer (bis-phenyl glycidyl dimethacrylate, i.e. Bis-GMA, and triethylene glycol dimethacrylate, i.e. TEGDMA), residual monomer release into water and the degree of monomer conversion (DC%) of glass fiber-reinforced composites (FRC) with a partially bioresorbable polymer matrix. Another aim was to find out whether the curing mode affects the quantity of residual monomer and degree of conversion. Glass fibers were preimpregnated with a bioresorbable poly(hydroxyproline) amide and non-resorbable Bis-GMA-TEGDMA resin system. Specimens were immersed in water for 1, 3 or 7 days (37 degrees C) to determine the quantity of leached residual monomers, or in the solvent tetrahydrofuran for 3 days to determine the total quantity of residual monomers by high performance liquid chromatography. DC% was measured by Fourier transform infrared spectroscopy. The quantity of residual monomer of the specimens decreased when the specimens contained glass fibers, and/or poly(hydroxyproline) amide, and/or when it was post-cured. The majority of the residual monomers were leached out during the first 24 h of immersion in water. The DC% of the specimens increased when post-cured. Also glass fibers in the composite increased the DC% in contrast to Bis-GMA-TEGDMA resin only. In conclusion, use of poly(hydroxyproline) amide as a sizing of the glass fibers in FRC does not increase the quantity of residual monomers. These results suggest that this new kind of partially bioresorbable FRC has potential for biomedical applications.

Interactions between resin monomers and commercial composite resins with human saliva derived esterases.

PubMed

Jaffer, F; Finer, Y; Santerre, J P

2002-04-01

Cholesterol esterase (CE) and pseudocholinesterase (PCE) have been reported to degrade commercial and model composite resins containing bisphenylglycidyl dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) or the latter in combination with urethane modified BisGMA monomer systems. In addition, human saliva has been shown to contain esterase like activities similar to CE and PCE. Hence, it was the aim of the current study to determine to what extent human saliva could degrade two common commercial composite resins (Z250 from 3M Inc. and Spectrum TPH from L.D. Caulk) which contain the above monomer systems. Saliva samples from different volunteers were collected, processed, pooled, and freeze-dried. TEGDMA and BisGMA monomers were incubated with human saliva derived esterase activity (HSDEA) and their respective hydrolysis was monitored using high performance liquid chromatography (HPLC). Both monomers were completely hydrolyzed within 25 h by HSDEA. Photopolymerized composites were incubated with buffer or human saliva (pH 7.0 and 37 C) for 2, 8 and 16 days. The incubation solutions were analyzed using HPLC and mass spectrometry. Surface morphology characterization was carried out using scanning electron microscopy. Upon biodegradation, the Z250 composite yielded higher amounts of BisGMA and TEGDMA related products relative to the TPH composite. However, there were higher amounts of ethoxylated bis-phenol A released from the TPH material. In terms of total mass of products released, human saliva demonstrated a greater ability to degrade Z250. In summary, HSDEA has been shown to contain esterase activities that can readily catalyze the biodegradation of current commercial composite resins.

High performance dental resin composites with hydrolytically stable monomers.

PubMed

Wang, Xiaohong; Huyang, George; Palagummi, Sri Vikram; Liu, Xiaohui; Skrtic, Drago; Beauchamp, Carlos; Bowen, Rafael; Sun, Jirun

2018-02-01

The objectives of this project were to: 1) develop strong and durable dental resin composites by employing new monomers that are hydrolytically stable, and 2) demonstrate that resin composites based on these monomers perform superiorly to the traditional bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) composites under testing conditions relevant to clinical applications. New resins comprising hydrolytically stable, ether-based monomer, i.e., triethylene glycol divinylbenzyl ether (TEG-DVBE), and urethane dimethacrylate (UDMA) were produced via composition-controlled photo-polymerization. Their composites contained 67.5wt% of micro and 7.5wt% of nano-sized filler. The performances of both copolymers and composites were evaluated by a battery of clinically-relevant assessments: degree of vinyl conversion (DC: FTIR and NIR spectroscopy); refractive index (n: optical microscopy); elastic modulus (E), flexural strength (F) and fracture toughness (K IC ) (universal mechanical testing); Knoop hardness (HK; indentation); water sorption (W sp ) and solubility (W su ) (gravimetry); polymerization shrinkage (S v ; mercury dilatometry) and polymerization stress (tensometer). The experimental UDMA/TEG-DVBE composites were compared with the Bis-GMA/TEGDMA composites containing the identical filler contents, and with the commercial micro hybrid flowable composite. UDMA/TEG-DBVE composites exhibited n, E, W sp , W su and S v equivalent to the controls. They outperformed the controls with respect to F (up to 26.8% increase), K IC (up to 27.7% increase), modulus recovery upon water sorption (full recovery vs. 91.9% recovery), and stress formation (up to 52.7% reduction). In addition, new composites showed up to 27.7% increase in attainable DC compared to the traditional composites. Bis-GMA/TEGDMA controls exceeded the experimental composites with respect to only one property, the composite hardness. Significantly, up to 18.1% lower HK values in the experimental series (0.458GPa) were still above the clinically required threshold of approx. 0.4GPa. Hydrolytic stability, composition-controlled polymerization and the overall enhancement in clinically-relevant properties of the new resin composites make them viable candidates to replace traditional resin composites as a new generation of strong and durable dental restoratives. Copyright © 2017 The Academy of Dental Materials. All rights reserved.

Effect of hydrogen peroxide on the three-dimensional polymer network in composites.

PubMed

Durner, Jürgen; Stojanovic, Marija; Urcan, Ebru; Spahl, Werner; Haertel, Ursula; Hickel, Reinhard; Reichl, Franx-Xaver

2011-06-01

Less data are available about the effects of hydrogen peroxide on the three-dimensional polymer network of polymerized composites. Therefore the study was performed to test the effects of hydrogen peroxide on the three-dimensional polymer network in composites. Polymerized specimens from Tetric Flow®, Tetric Ceram® and Filtek™ Supreme XT were bleached with Opalescence® PF 15% for 5h or PF 35% for 0.5h, respectively, and then stored in methanol for 1d and 7d. Controls were unbleached specimens. The eluates were analyzed by gas chromatography/mass spectrometry. More methacrylic acid (MAA), bisphenol-A (BPA), ethoxylated bisphenol-A-dimethacrylate (BisEMA), hydroquinone monomethyl ether (HQME), 1,10-decanediol dimethacrylate (DDDMA) and/or triethylene glycol dimethacrylate (TEGDMA) were eluted from bleached specimens compared with non bleached controls (1d). The highest DDDMA amount of 419.8 μmol/l was found in the eluates after 7d in Tetric Flow® specimens treated with PF 15. The highest HQME amount of 159.6 μmol/l was found in eluates from Tetric Ceram® specimens treated with PF after 7d. The highest TEGDMA amount of 178.7 μmol/l was found in eluates from Filtek™ Supreme XT specimens treated with PF 35 after 7d. Bleaching with hydrogen peroxide has an effect on the three-dimensional polymer network in polymerized composites leading to an increase in the release of unpolymerized monomers, additives and unspecific oxidative products. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Redline, Erica Marie; Bolintineanu, Dan S.; Lane, J. Matthew

The aim of this study was to alter polymerization chemistry to improve network homogeneity in free-radical crosslinked systems. It was hypothesized that a reduction in heterogeneity of the network would lead to improved mechanical performance. Experiments and simulations were carried out to investigate the connection between polymerization chemistry, network structure and mechanical properties. Experiments were conducted on two different monomer systems - the first is a single monomer system, urethane dimethacrylate (UDMA), and the second is a two-monomer system consisting of bisphenol A glycidyl dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) in a ratio of 70/30 BisGMA/TEGDMA by weight. Themore » methacrylate systems were crosslinked using traditional radical polymeriza- tion (TRP) with azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO) as an initiator; TRP systems were used as the control. The monomers were also cross-linked using activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) as a type of controlled radical polymerization (CRP). FTIR and DSC were used to monitor reac- tion kinetics of the systems. The networks were analyzed using NMR, DSC, X-ray diffraction (XRD), atomic force microscopy (AFM), and small angle X-ray scattering (SAXS). These techniques were employed in an attempt to quantify differences between the traditional and controlled radical polymerizations. While a quantitative methodology for characterizing net- work morphology was not established, SAXS and AFM have shown some promising initial results. Additionally, differences in mechanical behavior were observed between traditional and controlled radical polymerized thermosets in the BisGMA/TEGDMA system but not in the UDMA materials; this finding may be the result of network ductility variations between the two materials. Coarse-grained molecular dynamics simulations employing a novel model of the CRP reaction were carried out for the UDMA system, with parameters calibrated based on fully atomistic simulations of the UDMA monomer in the liquid state. Detailed metrics based on network graph theoretical approaches were implemented to quantify the bond network topology resulting from simulations. For a broad range of polymerization parameters, no discernible differences were seen between TRP and CRP UDMA simulations at equal conversions, although clear differences exist as a function of conversion. Both findings are consistent with experiments. Despite a number of shortcomings, these models have demonstrated the potential of molecular simulations for studying network topology in these systems.« less

Improved performance of Bis-GMA/TEGDMA dental composites by net-like structures formed from SiO2 nanofiber fillers.

PubMed

Wang, Xiaoyan; Cai, Qing; Zhang, Xuehui; Wei, Yan; Xu, Mingming; Yang, Xiaoping; Ma, Qi; Cheng, Yali; Deng, Xuliang

2016-02-01

The major objective of this study was to explore the effects of silicon dioxide (SiO2) nanofibers on the performance of 2, 2-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA)/tri-(ethyleneglycol) dimethacrylate (TEGDMA) dental composites. At first, the mechanical properties of Bis-GMA/TEGDMA (50/50, w/w) resins containing different contents of SiO2 nanofibers were evaluated to identify the appropriate composition to achieve the significant reinforcing effect. Secondly, optimized contents (5 or 10wt.%) of SiO2 nanofibers were mixed into resins together with SiO2 microparticles, which was 60wt.% of the resin. Controls for comparison were Bis-GMA/TEGDMA resins containing only SiO2 microparticles (60wt.%) or with additional SiO2 nanoparticles (5 or 10wt.%). Properties including abrasion, polymerization shrinkage and mechanical properties were evaluated to determine the contribution of SiO2 nanofibers. In comparison with SiO2 nanoparticles, SiO2 nanofibers improved the overall performance of Bis-GMA/TEGDMA composite resins, especially in improving abrasion resistance and decreasing polymerization shrinkage. The explanations were that one-dimensional SiO2 nanofibers were able to shield particular fillers from being abraded off, and able to form a kind of overlapped fibrous network to resist polymerization shrinkage. With these approaches, SiO2 nanofiber-containing Bis-GMA composite resins were envisioned a promising choice to achieve long-term durable restorations in clinical therapies. Copyright © 2015. Published by Elsevier B.V.

Residual HEMA and TEGDMA Release and Cytotoxicity Evaluation of Resin-Modified Glass Ionomer Cement and Compomers Cured with Different Light Sources

PubMed Central

Botsali, Murat Selim; Kuşgöz, Adem; Altintaş, Subutay Han; Ülker, Hayriye Esra; Kiliç, Serdar; Başak, Feridun; Ülker, Mustafa

2014-01-01

The purpose of this study was first to evaluate the elution of 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) monomers from resin-modified glass ionomer cement (RMGIC) and compomers cured with halogen and light-emitting diode (LED) light-curing units (LCUs). The effect of cured materials on the viability of L929 fibroblast cells was also evaluated. One RMGIC (Ketac N100) and two compomers (Dyract Extra and Twinkystar) were tested. Materials were prepared in teflon disks and light-cured with LED or halogen LCUs. The residual monomers of resin materials in solution were identified using high-performance liquid chromatography. The fibroblast cells' viability was analyzed using MTT assay. The type of LCU did not have a significant effect on the elution of HEMA and TEGDMA. A greater amount of HEMA than TEGMDA was eluted. The amount of TEGDMA eluted from Twinkystar was greater than Dyract Extra (P < 0.05) when cured with a halogen LCU. All material-LCU combinations decreased the fibroblast cells' viability more than the control group (P < 0.01), except for Dyract Extra cured with a halogen LCU (P > 0.05). Curing with the LED LCU decreased the cells' viability more than curing with the halogen LCU for compomers. For Ketac N100, the halogen LCU decreased the cells' viability more than the LED LCU. PMID:24592149

Application of solid phase microextraction on dental composite resin analysis.

PubMed

Wang, Ven-Shing; Chang, Ta-Yuan; Lai, Chien-Chen; Chen, San-Yue; Huang, Long-Chen; Chao, Keh-Ping

2012-08-15

A direct immersion solid phase microextraction (DI-SPME) method was developed for the analysis of dentin monomers in saliva. Dentine monomers, such as triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA) and 2,2-bis-[4-(2-hydroxy-3-methacryloyloxypropoxy) phenyl]-propane (Bis-GMA), have a high molecular weight and a low vapor pressure. The polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber with a medium polarity was employed for DI-SPME, and 215 nm of detection wavelength was found to be optimum in the chromatogram of HPLC measurement. The calibration range for DI-SPME was 0.30-300 μg/mL with correlation coefficients (r) greater than 0.998 for each analyte. The DI-SPME method achieved good accuracy (recovery 96.1-101.2%) and precision (2.30-8.15% CV) for both intra- and inter-day assays of quality control samples for three target compounds. Method validation was performed on standards dissolved in blank saliva, and there was no significant difference (p>0.2) between the DI-SPME method and the liquid injection method. However, the detection limit of DI-SPME was as low as 0.03, 0.27 and 0.06 μg/mL for TEGDMA, UDMA and Bis-GMA, respectively. Real sample analyses were performed on commercial dentin products after curing for the leaching measurement. In summary, DI-SPME is a more sensitive method that requires less sample pretreatment procedures to measure the resin materials leached in saliva. Copyright © 2012 Elsevier B.V. All rights reserved.

Rheological properties of experimental Bis-GMA/TEGDMA flowable resin composites with various macrofiller/microfiller ratio.

PubMed

Beun, Sébastien; Bailly, Christian; Dabin, Anne; Vreven, José; Devaux, Jacques; Leloup, Gaëtane

2009-02-01

The purpose of this study was to investigate the rheological behavior of resin composites and to evaluate the influence of each component, organic as well as inorganic, on their viscoelastic properties by testing model experimental formulations. Several unfilled mixtures of 2,2-bis-[4-(methacryloxy-2-hydroxy-propoxy)-phenyl]-propane (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) were prepared as well as experimental flowable resin composites using a Bis-GMA/TEGDMA 50/50 wt% mixture as organic fraction filled at 60% in weight with varying ratios of silanated barium glass (1 microm) and partially hydrophobic fumed silica (0.1 microm). Their rheological properties were investigated using dynamic oscillatory rheometers. Transmission electron microscopy (TEM) was also performed to investigate the spatial organization of the filler particles. Unfilled Bis-GMA/TEGDMA mixtures all showed a Newtonian behavior. The experimental flowable resin composites were non-Newtonian, shear-thinning fluids. As the quantity of microfiller increased, the viscosity increased and the shear-thinning behavior increased as well. In addition, the experimental composites showed thixotropy, i.e. their viscosity is a function of time after deformation. All these properties were not specifically linked to the creation and destruction of a visible network between inorganic particles, as no difference could be seen between particles' spatial organization at the equilibrium rest state or immediately after deformation. The complex viscoelastic properties of resin composites are due to interactions between microfiller and monomer molecules. Modifying the chemical and physical properties of the particles' surface could possibly improve their flow properties and thus their clinical handling performances.

Control of polymerization shrinkage and stress in nanogel-modified monomer and composite materials

PubMed Central

Moraes, Rafael R.; Garcia, Jeffrey W.; Barros, Matthew D.; Lewis, Steven H.; Pfeifer, Carmem S.; Liu, JianCheng; Stansbury, Jeffrey W.

2011-01-01

Objectives This study demonstrates the effects of nano-scale prepolymer particles as additives to model dental monomer and composite formulations. Methods Discrete nanogel particles were prepared by solution photopolymerization of isobornyl methacrylate and urethane dimethacrylate in the presence of a chain transfer agent, which also provided a means to attach reactive groups to the prepolymer. Nanogel was added to triethylene glycol dimethacrylate (TEGDMA) in increments between 5 and 40 wt% with resin viscosity, reaction kinetics, shrinkage, mechanical properties, stress and optical properties evaluated. Maximum loading of barium glass filler was determined as a function of nanogel content and composites with varied nanogel content but uniform filler loading were compared in terms of consistency, conversion, shrinkage and mechanical properties. Results High conversion, high molecular weight internally crosslinked and cyclized nanogel prepolymer was efficiently prepared and redispersed into TEGDMA with an exponential rise in viscosity accompanying nanogel content. Nanogel addition at any level produced no deleterious effects on reaction kinetics, conversion or mechanical properties, as long as reactive nanogels were used. A reduction in polymerization shrinkage and stress was achieved in proportion to nanogel content. Even at high nanogel concentrations, the maximum loading of glass filler was only marginally reduced relative to the control and high strength composite materials with low shrinkage were obtained. Significance The use of reactive nanogels offers a versatile platform from which resin and composite handling properties can be adjusted while the polymerization shrinkage and stress development that challenge the adhesive bonding of dental restoratives are controllably reduced. PMID:21388669

Influence of matrix and filler fraction on biofilm formation on the surface of experimental resin-based composites.

PubMed

Ionescu, Andrei; Brambilla, Eugenio; Wastl, Daniel S; Giessibl, Franz J; Cazzaniga, Gloria; Schneider-Feyrer, Sibylle; Hahnel, Sebastian

2015-01-01

The aim of this study was to investigate the impact of resin matrix chemistry and filler fraction on biofilm formation on the surface of experimental resin-based composites (RBCs). Specimens were prepared from eight experimental RBC formulations differing in resin matrix blend (BisGMA/TEGDMA in a 7:3 wt% ratio or UDMA/aliphatic dimethacrylate in a 1:1 wt% ratio) and filler fraction (no fillers; 65 wt% dental glass with an average diameter of 7 or 0.7 µm or 65 wt% SiO2 with an average diameter of 20 nm). Surface roughness, surface free energy, and chemical surface composition were determined; surface topography was visualized using atomic force microscopy. Biofilm formation was simulated under continuous flow conditions for a 48 h period using a monospecies Streptococcus mutans and a multispecies biofilm model. In the monospecies biofilm model, the impact of the filler fraction overruled the influence of the resin matrix, indicating lowest biofilm formation on RBCs with nano-scaled filler particles and those manufactured from the neat resin blends. The multispecies model suggested a more pronounced effect of the resin matrix blend, as significantly higher biofilm formation was identified on RBCs with a UDMA/dimethacrylate matrix blend than on those including a BisGMA/TEGDMA matrix blend but analogous filler fractions. Although significant differences in surface properties between the various materials were identified, correlations between the surface properties and biofilm formation were poor, which highlights the relevance of surface topography and chemistry. These results may help to tailor novel RBC formulations which feature reduced biofilm formation on their surface.

Control of polymerization shrinkage and stress in nanogel-modified monomer and composite materials.

PubMed

Moraes, Rafael R; Garcia, Jeffrey W; Barros, Matthew D; Lewis, Steven H; Pfeifer, Carmem S; Liu, JianCheng; Stansbury, Jeffrey W

2011-06-01

This study demonstrates the effects of nano-scale prepolymer particles as additives to model dental monomer and composite formulations. Discrete nanogel particles were prepared by solution photopolymerization of isobornyl methacrylate and urethane dimethacrylate in the presence of a chain transfer agent, which also provided a means to attach reactive groups to the prepolymer. Nanogel was added to triethylene glycol dimethacrylate (TEGDMA) in increments between 5 and 40 wt% with resin viscosity, reaction kinetics, shrinkage, mechanical properties, stress and optical properties evaluated. Maximum loading of barium glass filler was determined as a function of nanogel content and composites with varied nanogel content but uniform filler loading were compared in terms of consistency, conversion, shrinkage and mechanical properties. High conversion, high molecular weight internally crosslinked and cyclized nanogel prepolymer was efficiently prepared and redispersed into TEGDMA with an exponential rise in viscosity accompanying nanogel content. Nanogel addition at any level produced no deleterious effects on reaction kinetics, conversion or mechanical properties, as long as reactive nanogels were used. A reduction in polymerization shrinkage and stress was achieved in proportion to nanogel content. Even at high nanogel concentrations, the maximum loading of glass filler was only marginally reduced relative to the control and high strength composite materials with low shrinkage were obtained. The use of reactive nanogels offers a versatile platform from which resin and composite handling properties can be adjusted while the polymerization shrinkage and stress development that challenge the adhesive bonding of dental restoratives are controllably reduced. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Application of clotrimazole via a novel controlled release device provides potent retinal protection.

PubMed

Nezhad, Zhaleh Kashkouli; Nagai, Nobuhiro; Yamamoto, Kotaro; Kaji, Hirokazu; Nishizawa, Matsuhiko; Saya, Hideyuki; Nakazawa, Toru; Abe, Toshiaki

2015-09-01

Age-related macular degeneration is the leading cause of legal blindness among older individuals. Therefore, the development of new therapeutic agents and optimum drug delivery systems for its treatment are crucial. In this study, we investigate whether clotrimazole (CLT) is capable of protecting retinal cells against oxidative-induced injury and the possible inhibitory effect of a sustained CLT-release device against light-induced retinal damage in rats. In vitro results indicated pretreatment of immortalized retinal pigment epithelium cells (RPE-J cells) with 10-50 µM CLT before exposure to oxygen/glucose deprivation conditions for 48 h decreased the extent of cell death, attenuated the percentage of reactive oxygen species-positive cells, and decreased the levels of cleaved caspase-3. The device consists of a separately fabricated reservoir, a CLT formulation, and a controlled release cover, which are made of poly(ethyleneglycol) dimethacrylate (PEGDM) and tri(ethyleneglycol) dimethacrylate (TEGDM). The release rate of CLT was successfully tuned by changing the ratio of PEGDM/TEGDM in the cover. In vivo results showed that use of a CLT-loaded device lessened the reduction of electroretinographic amplitudes after light exposure. These findings indicate that the application of a polymeric CLT-loaded device may be a promising method for the treatment of some retinal disorders.

Stress reduction in phase-separated, cross-linked networks: influence of phase structure and kinetics of reaction

PubMed Central

Szczepanski, Caroline R.; Stansbury, Jeffrey W.

2014-01-01

A mechanism for polymerization shrinkage and stress reduction was developed for heterogeneous networks formed via ambient, photo-initiated polymerization-induced phase separation (PIPS). The material system used consists of a bulk homopolymer matrix of triethylene glycol dimethacrylate (TEGDMA) modified with one of three non-reactive, linear prepolymers (poly-methyl, ethyl and butyl methacrylate). At higher prepolymer loading levels (10–20 wt%) an enhanced reduction in both shrinkage and polymerization stress is observed. The onset of gelation in these materials is delayed to a higher degree of methacrylate conversion (~15–25%), providing more time for phase structure evolution by thermodynamically driven monomer diffusion between immiscible phases prior to network macro-gelation. The resulting phase structure was probed by introducing a fluorescently tagged prepolymer into the matrix. The phase structure evolves from a dispersion of prepolymer at low loading levels to a fully co-continuous heterogeneous network at higher loadings. The bulk modulus in phase separated networks is equivalent or greater than that of poly(TEGDMA), despite a reduced polymerization rate and cross-link density in the prepolymer-rich domains. PMID:25418999

Volumetric dimensional changes of dental light-cured dimethacrylate resins after sorption of water or ethanol.

PubMed

Sideridou, Irini D; Karabela, Maria M; Vouvoudi, Evagelia Ch

2008-08-01

This study evaluated the influence of water and ethanol sorption on the volumetric dimensional changes of resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D(3)MA. The resin specimens (15mm diameterx1mm height) were immersed in water or ethanol 37+/-1 degrees C for 30 days. Volumetric changes of specimens were obtained via accurate mass measurements using Archimedes principle. The specimens were reconditioned by dry storage in an oven at 37+/-1 degrees C until constant mass was obtained and then immersed in water or ethanol for 30 days. The volumetric changes of specimens were determined and compared to those obtained from the first sorption. Resins showed similar volume increase during the first and second sorptions of water or ethanol. The volume increase due to water absorption is in the following order: poly-TEGDMA>poly-Bis-GMA>poly-UDMA>poly-Bis-EMA>poly-D(3)MA. On the contrary, the order in ethanol is poly-Bis-GMA>poly-UDMA>poly-TEGDMA>poly-Bis-EMA approximately poly-D(3)MA. The volume increase was found to depend linearly on the amount of water or ethanol absorbed. In the choice of monomers for preparation of composite resin matrix the volume increase in the resin after immersion in water or ethanol must be taken into account. Resins of Bis-EMA and D(3)MA showed the lowest values.

Detection of leachables and cytotoxicity after exposure to methacrylate- and epoxy-based root canal sealers in vitro.

PubMed

Lodienė, Greta; Kopperud, Hilde M; Ørstavik, Dag; Bruzell, Ellen M

2013-10-01

Root canal sealing materials may have toxic potential in vitro depending on the cell line, cytotoxicity assay, material chemistry, and degree of polymer curing. The aims of the present study were to detect leaching components from epoxy- or methacrylate-based root canal sealers and to investigate the degree of cytotoxicity after exposure to extracts from these materials. Qualitative determination of substances released from the materials was performed by gas- and liquid chromatography/mass spectrometry. Submandibular salivary gland acinar cell death (apoptosis/necrosis) was determined using a fluorescence staining/microscopy technique. The major leachable monomer from the epoxy-based material was bisphenol-A diglycidyl ether (BADGE), whereas leachables from the methacrylate-based materials were mainly triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), hydroxyethyl methacrylate (HEMA), and polyethyleneglycol dimethacrylate (PEGDMA). Exposure to diluted extracts of cured methacrylate-based materials caused a postexposure time-dependent increase in cell death. This effect was not demonstrated as a result of exposure to undiluted extract of cured epoxy-based material. Extracts of all fresh materials induced apoptosis significantly, but at lower dilutions of the epoxy- than the methacrylate-based materials. The degree of leaching, determined from the relative chromatogram peak heights of eluates from the methacrylate-based sealer materials, corresponded with the degree of cell death induced by extracts of these materials. © 2013 Eur J Oral Sci.

Effect of Opalescence(®) bleaching gels on the elution of bulk-fill composite components.

PubMed

Schuster, Lena; Reichl, Franz-Xaver; Rothmund, Lena; He, Xiuli; Yang, Yang; Van Landuyt, Kirsten L; Kehe, Kai; Polydorou, Olga; Hickel, Reinhard; Högg, Christof

2016-02-01

Bleaching treatments can affect release of components from conventional composites. In this continuing study the influence of two different bleaching gels on the elution of bulk-fill composite components was investigated. The composites Tetric EvoCeram(®) Bulk Fill, QuiXFil™ and X-tra fil were treated with the bleaching gels Opalescence PF 15% (PF 15%) for 5 h and PF 35% (PF 35%) for 30 min and then stored in methanol and water for 24 h and 7 d. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). Unbleached specimens were used as control group. A total of 7 different elutable substances have been identified from the investigated composites after bleaching-treatment. Three of them were methacrylates: 2-hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA) and trimethylolpropane trimethacrylate (TMPTMA). Compared to the unbleached controls an increase in elution after PF 15%-treatment of following compounds was found: HEMA (Tetric EvoCeram(®) Bulk Fill), TEGDMA (QuiXFil™, X-tra fil) and 4-N,N-dimethylaminobenzoic acid butyl ethoxy ester (DMABEE) (Tetric EvoCeram(®) Bulk Fill, QuiXFil™, X-tra fil). Following compounds showed a reduction in elution after PF 35%-treatment compared to controls: TEGDMA (QuiXFil™) and DMABEE (Tetric EvoCeram(®) Bulk Fill). The highest concentration of HEMA was 0.22 mmol/l (Tetric EvoCeram(®) Bulk Fill, methanol, 7 d, PF 15%), the highest concentration of TEGDMA was 0.3 mmol/l (X-tra fil, water, 7 d, PF 15%) and the highest concentration of DMABEE was 0.05 mmol/l (QuiXFil™, water, 7 d, PF 35%). PF 15% and PF 35% can lead to reduced and/or increased elution of some bulk-fill components, compared to unbleached bulk-fill composites. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Novel dental adhesive containing antibacterial agents and calcium phosphate nanoparticles

PubMed Central

Melo, Mary Anne S.; Cheng, Lei; Weir, Michael D.; Hsia, Ru-ching; Rodrigues, Lidiany K. A.; Xu, Hockin H. K.

2013-01-01

Secondary caries remains the main reason for dental restoration failure. Replacement of failed restorations accounts for 50-70% of all restorations performed. Antibacterial adhesives could inhibit biofilm acids at tooth-restoration margins, and calcium phosphate (CaP) ions could remineralize tooth lesions. The objectives of this study were to: (1) incorporate nanoparticles of silver (NAg), quaternary ammonium dimethacrylate (QADM), and nanoparticles of amorphous calcium phosphate (NACP) into bonding agent; and (2) investigate their effects on dentin bonding and microcosm biofilms. An experimental primer was made with pyromellitic glycerol dimethacrylate (PMGDM) and 2-hydroxyethyl methacrylate (HEMA). An adhesive was made with bisphenol-A-glycerolate dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA). NAg was incorporated into primer at 0.1wt%. The adhesive contained 0.1% NAg and 10% QADM, and 0-40% NACP. Incorporating NAg into primer and NAg-QADM-NACP into adhesive did not adversely affect dentin bond strength (p>0.1). SEM showed numerous resin tags, and TEM revealed NAg and NACP in dentinal tubules. Viability of human saliva microcosm biofilms on primer/adhesive/composite disks was substantially reduced via NAg and QADM. Metabolic activity, lactic acid, and colony-forming units of biofilms were much lower on the new bonding agents than control (p<0.05). In conclusion, novel dental bonding agents containing NAg, QADM and NACP were developed with the potential to kill residual bacteria in the tooth cavity and inhibit the invading bacteria along tooth-restoration margins, with NACP to remineralize tooth lesions. The novel method of combining antibacterial agents (NAg and QADM) with remineralizing agent (NACP) may have wide applicability to other adhesives for caries inhibition. PMID:23281264

BisGMA/TEGDMA dental nanocomposites containing glyoxylic acid modified high-aspect ratio hydroxyapatite nanofibers with enhanced dispersion

PubMed Central

Chen, Liang; Xu, Changqi; Wang, Yong; Shi, Jian; Yu, Qingsong

2012-01-01

The purpose of this research was to investigate the influence of the glyoxylic acid (GA) modification of hydroxyapatite (HAP) nanofibers on their dispersion in bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental composites and also investigate the mechanical properties, water absorption, and water solubility of the resulting dental resins and composites. Scanning/Transmission electron microscopy (STEM) images showed that microsized HAP nanofiber bundles could be effectively broken down to individual HAP nanofibers with an average length of ~15 μm after the surface modification process. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) characterization confirmed glyoxylic acid was chemically grafted on the HAP nanofiber surface, hypothetically by reacting with the amine group on HAP nanofiber surface. The enhanced dispersion of HAP nanofibers in dental matrix led to increased biaxial flexural strength (BFS) compared with the corresponding dental resins and composites filled with untreated HAP nanofibers. In addition, impregnation of small mass fractions of the glyoxylic acid modified HAP nanofibers into the BisGMA/TEGDMA dental resins (5wt%, 10wt%) or composites (2wt%, 3wt%) could also substantially improve the BFS in comparison with the controls(pure resins or dental composites filled with silica particles alone). Larger mass fractions could not further increase the mechanical property or even degrade the BFS values. Water behavior testing results indicated that the addition of glyoxylic acid modified HAP nanofibers resulted in higher water absorption and water solubility values which is not preferred for clinical application. In summary, well dispersed HAP nanofibers and their dental composites with enhanced mechanical property have been successfully fabricated but the water absorption and water solubility of such dental composites need to be further improved. PMID:22689264

Mechanical behavior of bioactive composite cements consisting of resin and glass-ceramic powder in a simulated body fluid: effect of silane coupling agent.

PubMed

Miyata, N; Matsuura, W; Kokubo, T; Nakamura, T

2004-09-01

Time-dependent strength behavior was investigated for bisphenol-a-glycidyl methacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) resin cements combined with glass-ceramic A-W filler treated with various kinds of silane coupling agents. The fracture strength of the composite resin cements was measured by three-point bending as a function of stressing rate in a simulated body fluid (SBF), and thereby the stress-corrosion susceptibility constant was evaluated. The fracture strength was found to depend on the kind of coupling agent used. For the present Bis-GMA/TEGDMA resin, the silane coupling agents without hydrophilic amine groups can be used to obtain good adhesion between resin and A-W filler owing to their nature of co-polymerizing with the resin. On the other hand, all the composite resin cements showed nearly the same degree of stress-corrosion susceptibility whether the A-W fillers were treated or untreated with silane coupling agents. This means that the stress-corrosion susceptibility of the present composite cements is predominantly affected by that of the matrix resin. Thus, the microcrack formation and growth at the resin matrix near particle - resin interface were thought to determine overall time-dependent strength behavior of the composite cements.

A new approach to network heterogeneity: Polymerization Induced Phase Separation in photo-initiated, free-radical methacrylic systems

PubMed Central

Szczepanski, Caroline R.; Pfeifer, Carmem S.; Stansbury, Jeffrey W.

2012-01-01

Non-reactive, thermoplastic prepolymers (poly- methyl, ethyl and butyl methacrylate) were added to a model homopolymer matrix composed of triethylene glycol dimethacrylate (TEGDMA) to form heterogeneous networks via polymerization induced phase separation (PIPS). PIPS creates networks with distinct phase structure that can partially compensate for volumetric shrinkage during polymerization through localized internal volume expansion. This investigation utilizes purely photo-initiated, free-radical systems, broadening the scope of applications for PIPS since these processing conditions have not been studied previously. The introduction of prepolymer into TEGDMA monomer resulted in stable, homogeneous monomer formulations, most of which underwent PIPS upon photo-irradiation, creating heterogeneous networks. During polymerization the presence of prepolymer enhanced autoacceleration, allowing for a more extensive ambient cure of the material. Phase separation, as characterized by dynamic changes in sample turbidity, was monitored simultaneously with monomer conversion and either preceded or was coincident with network gelation. Dynamic mechanical analysis shows a broadening of the tan delta peak and secondary peak formation, characteristic of phase-separated materials, indicating one phase rich in prepolymer and another depleted form upon phase separation. In certain cases, PIPS leads to an enhanced physical reduction of volumetric shrinkage, which is attractive for many applications including dental composite materials. PMID:23109733

Development of high-viscosity, two-paste bioactive bone cements.

PubMed

Deb, S; Aiyathurai, L; Roether, J A; Luklinska, Z B

2005-06-01

Self-curing two-paste bone cements have been developed using methacrylate monomers with a view to formulate cements with low polymerization exotherm, low shrinkage, better mechanical properties, and improved adhesion to bone and implant surfaces. The monomers include bis-phenol A glycidyl dimethacrylate (bis-GMA), urethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) as a viscosity modifier. Two-paste systems were formulated containing 60% by weight of a bioactive ceramic, hydroxyapatite. A methacroyloxy silane (A174) was used as a coupling agent due to its higher water stability in comparison to other aminosilanes to silanate the hydroxyapatite particles prior to composite formulation. A comparison of the FT-infrared spectrum of hydroxyapatite and silanated hydroxyapatite showed the presence of the carbonyl groups ( approximately 1720 cm(-1)), -C=C-( approximately 1630 cm(-1)) and Si-O- (1300-1250 cm(-1)) which indicated the availability of silane groups on the filler surface. Two methods of mixing were effected to form the bone cement: firstly by mixing in an open bowl and secondly by extruding the two pastes by an auto-mixing tip using a gun to dispense the pastes. Both types of cements yielded low polymerization exotherms with good mechanical properties; however, the lower viscosity of UDMA allowed better extrusion and handling properties. A biologically active apatite layer formed on the bone cement surface within a short period after its immersion in simulated body fluid, demonstrating in vitro bioactivity of the composite. This preliminary data thus suggests that UDMA is a viable alternative to bis-GMA as a polymerizable matrix in the formation of bone cements.

Measurement of solubility and water sorption of dental nanocomposites light cured by argon laser.

PubMed

Mirsasaani, Seyed Shahabeddin; Ghomi, Farhad; Hemati, Mehran; Tavasoli, Tina

2013-03-01

Different parameters used for photoactivation process and also composition provide changes in the properties of dental composites. In the present work the effect of different power density of argon laser and filler loading on solubility (SL) and water sorption (WS) of light-cure dental nanocomposites was studied. The resin of nanocomposites was prepared by mixing bisphenol A glycol dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) with a mass ratio of 65/35. 20 wt.% and 25 wt.% of nanosilica fillers with a primary particle size of 10 nm were added to the resin. Camphorquinone (CQ) and DMAEMA were added as photoinitiator system. The nanocomposites were cured by applying the laser beam at the wavelength of 472 nm and power densities of 260 and 340 mW/cm(2) for 40 sec. Solubility and water sorption were then measured according to ISO 4049, which in our case, the maximums were 2.2% and 4.3% at 260 mW/cm(2) and 20% filler, respectively. The minimum solubility (1.2%) and water sorption (3.8%) were achieved for the composite containing 25% filler cured at 340 mW/cm(2). The results confirmed that higher power density and filler loading decreased solubility of unreacted monomers and water sorption and improved physico-mechanical properties of nanocomposites.

Correlation of shear and dielectric ion viscosity of dental resins - Influence of composition, temperature and filler content.

PubMed

Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Selig, Daniela; Duvenbeck, Fabian; Moeginger, Bernhard

2016-07-01

Shear viscosity and ion viscosity of uncured visible light-curing (VLC) resins and resin based composites (RBC) are correlated with respect to the resin composition, temperature and filler content to check where Dielectric Analysis (DEA) investigations of VLC RBC generate similar results as viscosity measurements. Mixtures of bisphenol A glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) as well as the pure resins were investigated and compared with two commercial VLC dental resins and RBCs (VOCO, Arabesk Top and Grandio). Shear viscosity data was obtained using a Haake Mars III, Thermo Scientific. Ion viscosity measurements performed by a dielectric cure analyzer (DEA 231/1 Epsilon with Mini IDEX-Sensor, Netzsch-Gerätebau). Shear viscosity depends reciprocally on the mobility of molecules, whereas the ion viscosity also depends on the ion concentration as it is affected by both ion concentration and mixture viscosity. Except of pure TEGDMA, shear and ion viscosities depend on the resin composition qualitatively in a similar manner. Furthermore, shear and ion viscosities of the commercial VLC dental resins and composites exhibited the same temperature dependency regardless of filler content. Application of typical rheological models (Kitano and Quemada) revealed that ion viscosity measurements can be described with respect to filler contents of up to 30vol.%. Rheological behavior of a VLC RBC can be characterized by DEA under the condition that the ion concentration is kept constant. Both methods address the same physical phenomenon - motion of molecules. The proposed relations allows for calculating the viscosity of any Bis-GMA-TEGDMA mixture on the base of the viscosities of the pure components. This study demonstrated the applicability of DEA investigations of VLC RBCs with respect to quality assurance purposes. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Microleakage of Glass Ionomer-based Provisional Cement in CAD/CAM-Fabricated Interim Crowns: An in vitro Study.

PubMed

Farah, Ra'fat I; Al-Harethi, Naji

2016-10-01

The aim of this study was to compare in vitro the marginal microleakage of glass ionomer-based provisional cement with resin-based provisional cement and zinc oxide non-eugenol (ZONE) provisional cement in computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated interim restorations. Fifteen intact human premolars were prepared in a standardized manner for complete coverage of crown restorations. Interim crowns for the prepared teeth were then fabricated using CAD/CAM, and the specimens were randomized into three groups of provisional cementing agents (n = 5 each): Glass ionomer-based provisional cement (GC Fuji TEMP LT™), bisphenol-A-glycidyldimethacrylate (Bis-GMA)/ triethylene glycol dimethacrylate (TEGDMA) resin-based cement (UltraTemp® REZ), and ZONE cement (TempBond NE). After 24 hours of storage in distilled water at 37°C, the specimens were thermocycled and then stored again for 24 hours in distilled water at room temperature. Next, the specimens were placed in freshly prepared 2% aqueous methylene blue dye for 24 hours and then embedded in autopolymerizing acrylic resin blocks and sectioned in buccolingual and mesiodistal directions to assess dye penetration using a stereomicroscope. The results were statistically analyzed using a nonparametric Kruskal-Wallis test. Dunn's post hoc test with a Bonferroni correction test was used to compute multiple pairwise comparisons that identified differences among groups; the level of significance was set at p < 0.05. All groups exhibited marginal microleakage; the Bis-GMA/TEGDMA resin-based provisional cement demonstrated the lowest microleakage scores, which were statistically different from those of the glass ionomer-based provisional cement and the ZONE cement. The provisional cementing agents exhibited different sealing abilities. The Bis-GMA/TEGDMA resin-based provisional cement exhibited the most effective favorable sealing properties against dye penetration compared with the glass ionomer-based provisional cement and conventional ZONE cement. Newly introduced glass ionomer-based provisional cement proved to be inferior to resin-based provisional cement as far as marginal microleakage is concerned.

Effect of surface preparation on the failure load of a highly filled composite bonded to the polymer-monomer matrix of a fiber-reinforced composite.

PubMed

Shimizu, Hiroshi; Tsue, Fumitake; Chen, Zhao-Xun; Takahashi, Yutaka

2009-04-01

The purpose of the present study was to evaluate the effect of surface preparation on the maximum fracture load value of a highly filled composite bonded to the polymer-monomer matrix of a fiber-reinforced composite. A polymer-monomer matrix was made by mixing urethane dimethacrylate and triethyleneglycol dimethacrylate at a ratio of 1:1 with camphorquinone and 2-dimethylaminoethyl methacrylate as a light initiator. The matrix was then polymerized in a disk-shaped silicone mold with a light-polymerizing unit. The flat surfaces of the polymer-monomer matrix disk were prepared in one of the following ways: (1) without preparation; (2) application of silane coupling agent; or (3) application of matrix liquid and prepolymerization. A highly filled composite material was applied and polymerized with a light-polymerizing unit. Additional test specimens made entirely of the polymer-monomer matrix were fabricated as references; the disk and cylinder were fabricated in one piece using a mold specially made for the present study (group 4). Half the specimens were thermocycled up to 10,000 times in water with a 1-minute dwell time at each temperature (5 degrees C and 55 degrees C). The maximum fracture load values were determined using a universal testing machine (n = 10). The maximum fracture loads for group 3 were significantly enhanced both before and after thermocycling, whereas the maximum fracture loads of group 2 were significantly enhanced before thermocycling (p < 0.05); however, the failure loads decreased for all groups after thermocycling (p < 0.05). All the specimens in groups 1 and 2 debonded during thermocycling. The failure load of group 3 was significantly lower than that of group 4 both before and after thermocycling (p < 0.05). Within the limitations of the current in vitro study, the application and prepolymerization of a mixed dimethacrylate resin liquid prior to the application of a highly filled composite was an effective surface preparation for the polymer-monomer matrix of a fiber-reinforced composite; however, the bond durability may be insufficient.

Development of dental restorative materials based on visible light-cured multi-methacrylates

NASA Astrophysics Data System (ADS)

Tiba, Amer

The studies described in this dissertation focus on new visible light-curing (VLC) oligomers exhibiting low shrinkage, low water sorption, and improved mechanical properties. A family of multi-methacrylates, based on poly(isopropylidenediphenol) resin (BPA), was synthesized, characterized, and evaluated. The commercial BPA resin is prepared from enzymatic polymerization (oligomerization) of bisphenol A. The BPA resin, having an average of eight phenolic hydroxyl groups per molecule, was treated with propylene carbonate, and the resultant product, i.e., propoxylated BPA (PEBPA) oligomer, was confirmed by Fourier transform infrared spectroscopy (FT-IR) and sp{13}C nuclear magnetic resonance (NMR). The propoxylated BPA was subsequently treated with methacryloyl chloride to produce the multi-methacrylates, identified by FT-IR and NMR. The PEBPA oligomer multimethacrylate: triethylene glycol dimethacrylate (TEGDMA) (50:50/wt:wt) blends were combined with 0.5 wt. % camphoroquinone (CQ) and 1.0 wt. % N,N-dimethylaminoethyl methacrylate (DMAEMA). The control polymers were 2,2-bis(4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl) propane (BisGMA): TEGDMA(50:50/wt:wt) blends having the same levels of CQ/DMAEMA. Differential photocalorimetry (DPC) and differential scanning calorimetry (DSC) showed these multimethacrylate/TEGDMA (neat resin) blends have polymerization characteristics comparable to the BisGMA/TEGDMA controls. These new multifunctional oligomers have lower polymerization shrinkage and lower uptake of water and other liquids, compared to BisGMA based materials. In addition, two experimental oligomers, PEBPA #2 and #3, have higher compressive strength than the BisGMA control. A biocompatibility test of the polymerized multi-methacrylate resins was performed and compared with the conventional BisGMA/TEGDMA resin and blank controls, using cell culture techniques. Human gingival fibroblasts were used for biocompatibility evaluation of these resins. The results revealed that the BPA oligomer (multi-methacrylate) based resin significantly favored the cell growth of the human gingival fibroblasts, compared to the control. An experimental composite was made from EPBPA oligomers (multi-methacrylates). The compressive strength of the experimental EPBPA containing composite was not significantly different than the commercial composite Herculite HXR. SEM photomicrographs revealed more voids in the experimental composites than the commercial composite on both the external surfaces of the prepared specimens and the subsequent fractured surfaces. This is due to the molding technique for specimen preparation and lack of good mechanical mixing for filler incorporation prior to placement of the resin in the mold for subsequent photopolymerization. However, the water sorption for the experimental EPBPA-based composite was significantly lower than the commercial Herculite (HXR) composite. This is most likely related to the hydrophobic nature of the experimental resin. These results suggest that the new type of polyfunctional methacrylate oligomers (PEBPA) have potential application in formulating dental composites as direct esthetic restorative materials with improved properties.

NaF-loaded core-shell PAN-PMMA nanofibers as reinforcements for Bis-GMA/TEGDMA restorative resins.

PubMed

Cheng, Liyuan; Zhou, Xuegang; Zhong, Hong; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

2014-01-01

A kind of core-shell nanofibers containing sodium fluoride (NaF) was produced and used as reinforcing materials for dimethacrylate-based dental restorative resins in this study. The core-shell nanofibers were prepared by coaxial-electrospinning with polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) solutions as core and shell fluids, respectively. The produced PAN-PMMA nanofibers varied in fiber diameter and the thickness of PMMA shell depending on electrospinning parameters. NaF-loaded nanofibers were obtained by incorporating NaF nanocrystals into the core fluid at two loadings (0.8 or 1.0wt.%). Embedment of NaF nanocrystals into the PAN core did not damage the core-shell structure. The addition of PAN-PMMA nanofibers into Bis-GMA/TEGDMA clearly showed the reinforcement due to the good interfacial adhesion between fibers and resin. The flexural strength (Fs) and flexural modulus (Ey) of the composites decreased slightly as the thickness of PMMA shell increasing. Sustained fluoride releases with minor initial burst release were achieved from NaF-loaded core-shell nanofibers and the corresponding composites, which was quite different from the case of embedding NaF nanocrystals into the dental resin directly. The study demonstrated that NaF-loaded PAN-PMMA core-shell nanofibers were not only able to improve the mechanical properties of restorative resin, but also able to provide sustained fluoride release to help in preventing secondary caries. © 2013.

Development of new photopolymerizable dental sealants.

PubMed

Davidenko, N; Cohen, M E; Diaz, J M; Sastre, R

1998-01-01

This paper describes the results obtained in the optimization of the composition of dental sealants in relation to the nature and proportions of monomer mixtures and photoinitiating system employed. The quantification and variation of certain parameters which determine the quality of a dental sealant (such as viscosity and penetrating power, residual double bonds, solubility and absorption, volume shrinkage and certain specific mechanical properties) have resulted in the development of new formulations. The composition which has achieved the best results of all the above properties was that corresponding to the monomer mixture bis-GMA/tri(ethylene glycol) dimethacrylate (TEGDMA) 40/60 wt%, and the photoinitiating system camphorquinone (CQ) with co-initiators N,N,3,5-tetramethyaniline (TMA) or N,N-dimethyl-p-toluidine (DMPT) in the ratio 1:1. The final properties and characteristics of the obtained formulations are superior to those of commercial dental sealants currently in use.

Flexible fiber-reinforced composites with improved interfacial adhesion by mussel-inspired polydopamine and poly(methyl methacrylate) coating.

PubMed

Yi, Mi; Sun, Hongyang; Zhang, Hongcheng; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

2016-01-01

To obtain a kind of light-curable fiber-reinforced composite for dental restoration, an excellent interfacial adhesion between the fiber and the acrylate resin matrix is quite essential. Herein, surface modification on glass fibers were carried out by coating them with poly(methyl methacrylate) (PMMA), polydopamine (PDA), or both. The PMMA or PDA coating was performed by soaking fibers in PMMA/acetone solution or dopamine aqueous solution. PDA/PMMA co-coated glass fibers were obtained by further soaking PDA-coated fibers in PMMA/acetone solution. These modified fibers were impregnated with bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) (5:5, w/w) dental resin at a volume fraction of 75%, using unmodified fibers as reference. Light-cured specimens were submitted to evaluations including flexural properties, morphological observation, dynamic mechanical thermal analysis (DMTA) and pull-out test. In comparison with unmodified glass fibers, all the modified glass fibers showed enhancements in flexural strength and modulus of Bis-GMA/TEGDMA resin composites. Results of DMTA and pull-out tests confirmed that surface modification had significantly improved the interfacial adhesion between the glass fiber and the resin matrix. Particularly, the PDA/PMMA co-coated glass fibers displayed the most efficient reinforcement and the strongest interfacial adhesion due to the synergetic effects of PDA and PMMA. It indicated that co-coating method was a promising approach in modifying the interfacial compatibility between inorganic glass fiber and organic resin matrix. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrogel based sensor arrays (2 × 2) with perforated piezoresistive diaphragms for metabolic monitoring (in vitro)

PubMed Central

Orthner, M.P.; Lin, G.; Avula, M.; Buetefisch, S.; Magda, J.; Rieth, L.W.; Solzbacher, F.

2010-01-01

This report details the first experimental results from novel hydrogel sensor array (2 × 2) which incorporates analyte diffusion pores into a piezoresistive diaphragm for the detection of hydrogel swelling pressures and hence chemical concentrations. The sensor assembly was comprised of three components, the active four sensors, HPMA/DMA/TEGDMA (hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA)) hydrogel, and backing plate. Each of the individual sensors of the array can be used with various hydrogels used to measure the presence of a number of stimuli including pH, ionic strength, and glucose concentrations. Ideally, in the future, these sensors will be used for continuous metabolic monitoring applications and implanted subcutaneously. In this paper and to properly characterize the sensor assembly, hydrogels sensitive to changes ionic strength were synthesized using hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA) and inserted into the sensor assembly. This hydrogel quickly and reversibly swells when placed environments of physiological buffer solutions (PBS) with ionic strengths ranging from 0.025 to 0.15 M, making it ideal for proof-of-concept testing and initial characterization. The assembly was wire bonded to a printed circuit board and coated with 3 ± 0.5 μm of Parylene-C using chemical vapor deposition (CVD) to protect the sensor and electrical connections during ionic strength wet testing. Two versions of sensors were fabricated for comparison, the first incorporated diffusion pores into the diaphragm, and the second used a solid diaphragm with perforated backing plate. This new design (perforated diaphragm) was shown to have slightly higher sensitivity than solid diaphragm sensors with separate diffuse backing plates when coupled with the hydrogel. The sensitivities for the 1 mm × 1 mm, 1.25 mm × 1.25 mm, 1.5 mm × 1.5 mm perforated diaphragm sensors were 53.3 ± 6.5, 171.7 ± 8.8, and 271.47 ± 27.53 mV/V-M, respectively. These results show that perforations in the diaphragm can be used not only to allow the diffusion of analyte into the cavity but to increase mechanical stress in the piezoresistive diaphragm, thereby increasing sensor output signal. The time constants for swelling (τswelling) and contracting (τcontracting) were calculated by fitting the sensor output half cycles to an exponential growth function. We found that the sensors' response was initially retarded during the preliminary hydrogel conditioning period then improved after 3–5 cycles with values of approximately 9 and 7 min for τswelling and τcontracting. For all sensors tested τswelling > τcontracting. This may be due to the increased loading on the hydrogel from the diaphragm during the swelling process. During contraction the diaphragm aids the hydrogel by reversibly applying mechanical pressure and therefore reducing τcontracting. Long term stability testing showed the sensors remained functional for upwards of 2 weeks in the test phosphate buffer solution (PBS). PMID:23750073

Hydrogel based sensor arrays (2 × 2) with perforated piezoresistive diaphragms for metabolic monitoring (in vitro).

PubMed

Orthner, M P; Lin, G; Avula, M; Buetefisch, S; Magda, J; Rieth, L W; Solzbacher, F

2010-03-19

This report details the first experimental results from novel hydrogel sensor array (2 × 2) which incorporates analyte diffusion pores into a piezoresistive diaphragm for the detection of hydrogel swelling pressures and hence chemical concentrations. The sensor assembly was comprised of three components, the active four sensors, HPMA/DMA/TEGDMA (hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA)) hydrogel, and backing plate. Each of the individual sensors of the array can be used with various hydrogels used to measure the presence of a number of stimuli including pH, ionic strength, and glucose concentrations. Ideally, in the future, these sensors will be used for continuous metabolic monitoring applications and implanted subcutaneously. In this paper and to properly characterize the sensor assembly, hydrogels sensitive to changes ionic strength were synthesized using hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA) and inserted into the sensor assembly. This hydrogel quickly and reversibly swells when placed environments of physiological buffer solutions (PBS) with ionic strengths ranging from 0.025 to 0.15 M, making it ideal for proof-of-concept testing and initial characterization. The assembly was wire bonded to a printed circuit board and coated with 3 ± 0.5 μm of Parylene-C using chemical vapor deposition (CVD) to protect the sensor and electrical connections during ionic strength wet testing. Two versions of sensors were fabricated for comparison, the first incorporated diffusion pores into the diaphragm, and the second used a solid diaphragm with perforated backing plate. This new design (perforated diaphragm) was shown to have slightly higher sensitivity than solid diaphragm sensors with separate diffuse backing plates when coupled with the hydrogel. The sensitivities for the 1 mm × 1 mm, 1.25 mm × 1.25 mm, 1.5 mm × 1.5 mm perforated diaphragm sensors were 53.3 ± 6.5, 171.7 ± 8.8, and 271.47 ± 27.53 mV/V-M, respectively. These results show that perforations in the diaphragm can be used not only to allow the diffusion of analyte into the cavity but to increase mechanical stress in the piezoresistive diaphragm, thereby increasing sensor output signal. The time constants for swelling ( τ swelling ) and contracting ( τ contracting ) were calculated by fitting the sensor output half cycles to an exponential growth function. We found that the sensors' response was initially retarded during the preliminary hydrogel conditioning period then improved after 3-5 cycles with values of approximately 9 and 7 min for τ swelling and τ contracting . For all sensors tested τ swelling > τ contracting . This may be due to the increased loading on the hydrogel from the diaphragm during the swelling process. During contraction the diaphragm aids the hydrogel by reversibly applying mechanical pressure and therefore reducing τ contracting . Long term stability testing showed the sensors remained functional for upwards of 2 weeks in the test phosphate buffer solution (PBS).

Occupational methacrylate and acrylate allergy--cross-reactions and possible screening allergens.

PubMed

Aalto-Korte, Kristiina; Henriks-Eckerman, Maj-Len; Kuuliala, Outi; Jolanki, Riitta

2010-12-01

Acrylic resin monomers, especially acrylates and methacrylates, are important occupational allergens. To analyse patterns of concomitant patch test reactions to acrylic monomers in relation to exposure, and to suggest possible screening allergens. We reviewed the patch test files for the years 1994-2009 at the Finnish Institute of Occupational Health for allergic reactions to acrylic monomers, and analysed the clinical records of sensitized patients. In a group of 66 patients allergic to an acrylic monomer, the most commonly positive allergens were three methacrylates, namely ethyleneglycol dimethacrylate (EGDMA), 2-hydroxyethyl methacrylate (2-HEMA) and 2-hydroxypropyl methacrylate (2-HPMA), and an acrylate, namely diethyleneglycol diacrylate (DEGDA). The patterns of concomitant reactions imply that exposure to methacrylates may induce cross-reactivity to acrylates, whereas exposure to acrylates usually does not lead to cross-allergy to methacrylates. Screening for triethyleneglycol diacrylate (TREGDA) in the baseline series was found to be useful, as 3 of 8 patients with diagnosed occupational acrylate allergy might have been missed without the screening. A short screening series of four allergens, EGDMA, DEGDA, 2-HPMA and pentaerythritol triacrylate (PETA), would have screened 93% of our 66 patients; each of the remaining 5 patients reacted to different acrylic monomer(s). © 2010 John Wiley & Sons A/S.

Preparation and characterization of silane-modified SiO2 particles reinforced resin composites with fluorinated acrylate polymer.

PubMed

Liu, Xue; Wang, Zengyao; Zhao, Chengji; Bu, Wenhuan; Na, Hui

2018-04-01

A series of fluorinated dental resin composites were prepared with two kinds of SiO 2 particles. Bis-GMA (bisphenol A-glycerolate dimethacrylate)/4-TF-PQEA (fluorinated acrylate monomer)/TEGDMA (triethylene glycol dimethacrylate) (40/30/30, wt/wt/wt) was introduced as resin matrix. SiO 2 nanopartices (30nm) and SiO 2 microparticles (0.3µm) were silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) and used as fillers. After mixing the resin matrix with 0%, 10%, 20%, 30% SiO 2 nanopartices and 0%, 10%, 20%, 30%, 40%, 50% SiO 2 microparticles, respectively, the fluorinated resin composites were obtained. Properties including double bond conversion (DC), polymerization shrinkage (PS), water sorption (W p ), water solubility (W y ), mechanical properties and cytotoxicity were investigated in comparison with those of neat resin system. The results showed that, filler particles could improve the overall performance of resin composites, particularly in improving mechanical properties and reducing PS of composites along with the addition of filler loading. Compared to resin composites containing SiO 2 microparticles, SiO 2 nanoparticles resin composites had higher DC, higher mechanical properties, lower PS and lower W p under the same filler content. Especially, 50% SiO 2 microparticles reinforced resins exhibited the best flexural strength (104.04 ± 7.40MPa), flexural modulus (5.62 ± 0.16GPa), vickers microhardness (37.34 ± 1.13 HV), compressive strength (301.54 ± 5.66MPa) and the lowest polymerization (3.42 ± 0.22%). Copyright © 2018 Elsevier Ltd. All rights reserved.

Property evolution during vitrification of dimethacrylate photopolymer networks

PubMed Central

Abu-Elenain, Dalia; Lewis, Steven H.; Stansbury, Jeffrey W.

2013-01-01

Objectives This study seeks to correlate the interrelated properties of conversion, shrinkage, modulus and stress as dimethacrylate networks transition from rubbery to glassy states during photopolymerization. Methods An unfilled BisGMA/TEGDMA resin was photocured for various irradiation intervals (7–600 s) to provide controlled levels of immediate conversion, which was monitored continuously for 10 min. Fiber optic near-infrared spectroscopy permitted coupling of real-time conversion measurement with dynamic polymerization shrinkage (linometer), modulus (dynamic mechanical analyzer) and stress (tensometer) development profiles. Results The varied irradiation conditions produced final conversion ranging from 6 % to more than 60 %. Post-irradiation conversion (dark cure) was quite limited when photopolymerization was interrupted either at very low or very high levels of conversion while significant dark cure contributions were possible for photocuring reactions suspended within the post-gel, rubbery regime. Analysis of conversion-based property evolution during and subsequent to photocuring demonstrated that the shrinkage rate increased significantly at about 40 % conversion followed by late-stage suppression in the conversion-dependent shrinkage rate that begins at about 45–50 % conversion. The gradual vitrification process over this conversion range is evident based on the broad but well-defined inflection in the modulus versus conversion data. As limiting conversion is approached, modulus and, to a somewhat lesser extent, stress rise precipitously as a result of vitrification with the stress profile showing little if any late-stage suppression as seen with shrinkage. Significance Near the limiting conversion for this model resin, the volumetric polymerization shrinkage rate slows while an exponential rise in modulus promotes the vitrification process that appears to largely dictate stress development. PMID:24080378

Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study.

PubMed

Chadda, Harshita; Naveen, Sangeetha Vasudevaraj; Mohan, Saktiswaren; Satapathy, Bhabani K; Ray, Alok R; Kamarul, Tunku

2016-07-01

Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail. The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination. Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software. Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis. The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Formation of functionalized nanoclusters by solvent evaporation and their effect on the physicochemical properties of dental composite resins.

PubMed

Rodríguez, Henry A; Giraldo, Luis F; Casanova, Herley

2015-07-01

The aim of this work was to study the effect of silica nanoclusters (SiNC), obtained by a solvent evaporation method and functionalized by 3-methacryloxypropyltrimethoxysilane (MPS) and MPS+octyltrimethoxysilane (OTMS) (50/50wt/wt), on the rheological, mechanical and sorption properties of urethane dimethylacrylate (UDMA)/triethylenglycol dimethacrylate (TEGDMA) (80/20wt/wt) resins blend. Silica nanoparticles (SiNP) were silanized with MPS or MPS+OTMS (50/50wt/wt) and incorporated in an UDMA-isopropanol mix to produce functionalized silica nanoclusters after evaporating the isopropanol. The effect of functionalized SiNC on resins rheological properties was determined by large and small deformation tests. Mechanical, thermal, sorption and solubility properties were evaluated for composite materials. The UDMA/TEGDMA (80/20wt/wt) resins blend with added SiNC (ca. 350nm) and functionalized with MPS showed a Newtonian flow behavior associated to their spheroidal shape, whereas the resins blend with nanoclusters silanized with MPS+OTMS (50/50wt/wt) (ca. 400nm) showed a shear-thinning behavior due to nanoclusters irregular shape. Composite materials prepared with bare silica nanoclusters showed lower compressive strength than functionalized silica nanoclusters. MPS functionalized nanoclusters showed better mechanical properties but higher water sorption than functionalized nanoclusters with both silane coupling agents, MPS and OTMS. The solvent evaporation method applied to functionalized nanoparticles showed to be an alternative way to the sinterization method for producing nanoclusters, which improved some dental composite mechanical properties and reduced water sorption. The shape of functionalized silica nanoclusters showed to have influence on the rheological properties of SiNC resin suspensions and the mechanical and sorption properties of light cured composites. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Modification of linear prepolymers to tailor heterogeneous network formation through photo-initiated Polymerization-Induced Phase Separation

PubMed Central

Szczepanski, Caroline R.; Stansbury, Jeffrey W.

2015-01-01

Polymerization-induced phase separation (PIPS) was studied in ambient photopolymerizations of triethylene glycol dimethacrylate (TEGDMA) modified by poly(methyl methacrylate) (PMMA). The molecular weight of PMMA and the rate of network formation (through incident UV-irradiation) were varied to influence both the promotion of phase separation through increases in overall free energy, as well as the extent to which phase development occurs during polymerization through diffusion prior to network gelation. The overall free energy of the polymerizing system increases with PMMA molecular weight, such that PIPS is promoted thermodynamically at low loading levels (5 wt%) of a higher molecular weight PMMA (120 kDa), while a higher loading level (20 wt%) is needed to induce PIPS with lower PMMA molecular weight (11 kDa), and phase separation was not promoted at any loading level tested of the lowest molecular weight PMMA (1 kDa). Due to these differences in overall free energy, systems modified by PMMA (11 kDa) underwent phase separation via Nucleation and Growth, and systems modified by PMMA (120 kDa), followed the Spinodal Decomposition mechanism. Despite differences in phase structure, all materials form a continuous phase rich in TEGDMA homopolymer. At high irradiation intensity (Io=20mW/cm2), the rate of network formation prohibited significant phase separation, even when thermodynamically preferred. A staged curing approach, which utilizes low intensity irradiation (Io=300µW/cm2) for the first ~50% of reaction to allow phase separation via diffusion, followed by a high intensity flood-cure to achieve a high degree of conversion, was employed to form phase-separated networks with reduced polymerization stress yet equivalent final conversion and modulus. PMID:26190865

Influence of bioactive particles on the chemical-mechanical properties of experimental enamel resin infiltrants.

PubMed

Sfalcin, Ravana Angelini; Correr, Américo Bortolazzo; Morbidelli, Lucas Rafael; Araújo, Tatiany Gabrielle Freire; Feitosa, Victor Pinheiro; Correr-Sobrinho, Lourenço; Watson, Timothy Frederick; Sauro, Salvatore

2017-07-01

This study aimed at evaluating the chemophysical properties of experimental resin infiltrants (ERIs) doped with different bioactive particles. A control resin infiltrant (CR) was formulated using triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (BisEMA). Moreover, five experimental ERIs were also created by incorporating the following bioactive fillers (10 wt%) into the CR: hydroxyapatite (Hap), amorphous calcium phosphate (ACP), zinc-polycarboxylated bioactive glass (BAG-Zn), bioactive glass 45S5 (BAG 45S5), and calcium silicate modified with beta tricalcium phosphate (β-TCP). ICON® resin infiltrant was also used as control. All the ERIs used in this study were assessed for degree of conversion (DC), Knoop microhardness (KHN), softening ratio (SR), tensile cohesive strength (TCS), modulus of elasticity (E-modulus), water sorption (WS), and solubility (SL). Data were subjected to ANOVA and Tukey's test (α = 5%). ICON® presented the lowest DC, KHN, TCS, E-modulus, and SR. Incorporation of bioactive fillers into CR caused significant increase in the KHN. Conversely, no significant effect was observed on DC, TCS, and E-modulus. The resin infiltrant containing Hap showed a significant increase in softening ratio, while, ICON® presented the highest WS and SL. The WS of ACP-doped resin infiltrant was significantly higher than that of the Hap-doped infiltrant. The SL of the ACP-doped infiltrant was higher than CR BAG-Zn or BAG 45S5. The incorporation of bioactive particles into experimental resin infiltrants can improve the chemomechanical properties and reduce water sorption and solubility. Resin infiltrants doped with bioactive particles may improve the long-term performance of the treatment of white-spot lesions.

Property evolution during vitrification of dimethacrylate photopolymer networks.

PubMed

Abu-elenain, Dalia A; Lewis, Steven H; Stansbury, Jeffrey W

2013-11-01

This study seeks to correlate the interrelated properties of conversion, shrinkage, modulus and stress as dimethacrylate networks transition from rubbery to glassy states during photopolymerization. An unfilled BisGMA/TEGDMA resin was photocured for various irradiation intervals (7-600 s) to provide controlled levels of immediate conversion, which was monitored continuously for 10 min. Fiber optic near-infrared spectroscopy permitted coupling of real-time conversion measurement with dynamic polymerization shrinkage (linometer), modulus (dynamic mechanical analyzer) and stress (tensometer) development profiles. The varied irradiation conditions produced final conversion ranging from 6% to more than 60%. Post-irradiation conversion (dark cure) was quite limited when photopolymerization was interrupted either at very low or very high levels of conversion while significant dark cure contributions were possible for photocuring reactions suspended within the post-gel, rubbery regime. Analysis of conversion-based property evolution during and subsequent to photocuring demonstrated that the shrinkage rate increased significantly at about 40% conversion followed by late-stage suppression in the conversion-dependent shrinkage rate that begins at about 45-50% conversion. The gradual vitrification process over this conversion range is evident based on the broad but well-defined inflection in the modulus versus conversion data. As limiting conversion is approached, modulus and, to a somewhat lesser extent, stress rise precipitously as a result of vitrification with the stress profile showing little if any late-stage suppression as seen with shrinkage. Near the limiting conversion for this model resin, the volumetric polymerization shrinkage rate slows while an exponential rise in modulus promotes the vitrification process that appears to largely dictate stress development. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Photoinitiation chemistry affects light transmission and degree of conversion of curing experimental dental resin composites.

PubMed

Ogunyinka, A; Palin, W M; Shortall, A C; Marquis, P M

2007-07-01

The effect of photoinitiator and co-initiator chemistry on the setting reaction and degree of conversion of dental resin-based composites (RBCs) has rarely been determined explicitly. This work examines the effect of type and concentration of photoinitiator and co-initiator on the rate of change of light transmission throughout polymerisation and degree of conversion of model RBC formulations. Bisphenol-A diglycidyl ether dimethacrylate (bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) (6:4 molar ratio) resins filled with silanized glass filler (74wt.%) and containing various photoinitiators (camphorquinone; CQ, 1-phenyl-1,2-propanedione; PPD, benzil; BZ), co-initiator types (N,N-dimethyl-p-amino benzoic acid ethyl ester; DABE, N,N-cyanoethyl methylaniline; CEMA, N,N-diethanol-p-toluidine; DEPT) and concentration (0.0-0.3% DABE) were polymerised using a halogen or LED light curing-unit (LCU) for 10, 20 and 40s. The setting reaction was monitored in real-time by measuring the light transmittance through the curing specimen and bulk degree of conversion (DC) evaluated using Fourier transform infra-red spectroscopy. Specimens containing CQ and PPD cured with the halogen LCU did not have a significant effect on DC or changes in light transmission, although a significant increase in DC was observed for CQ compared with PPD specimens cured with the LED LCU. DABE and CEMA were more effective co-initiators than DEPT. Although DC was not limited by co-initiator concentration, the absence of a co-initiator resulted in marked differences in light transmission and decreased DC throughout 40s irradiation with each LCU type. The spectral range emitted from different types of LCU and absorption characteristics of the photoinitiator chemistry of light-activated resin-based composites play a critical role in the efficiency of polymerisation.

Effects of water-aging on self-healing dental composite containing microcapsules.

PubMed

Wu, Junling; Weir, Michael D; Melo, Mary Anne S; Strassler, Howard E; Xu, Hockin H K

2016-04-01

The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. PUF microspheres were synthesized encapsulating a TEGDMA-DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness (KIC) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 day to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite (p>0.1). An excellent self-healing efficacy of 64-77% recovery was obtained (mean±sd; n=6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 day (p>0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air (p>0.1). A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of water-aging on self-healing dental composite containing microcapsules

PubMed Central

Wu, Junling; Weir, Michael D.; Melo, Mary Anne S.; Strassler, Howard E.; Xu, Hockin H. K.

2016-01-01

Objectives The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. Methods PUF microspheres were synthesized encapsulating a TEGDMA-DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness (KIC) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 d to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Results Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite (p > 0.1). An excellent self-healing efficacy of 64%–77% recovery was obtained (mean ± sd; n = 6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 d (p > 0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air (p > 0.1). Conclusions A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. Clinical significance The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity. PMID:26808158

Mechanical characterization and ion release of bioactive dental composites containing calcium phosphate particles.

PubMed

Natale, Livia C; Rodrigues, Marcela C; Alania, Yvette; Chiari, Marina D S; Boaro, Leticia C C; Cotrim, Marycel; Vega, Oscar; Braga, Roberto R

2018-08-01

to verify the effect of the addition of dicalcium phosphate dihydrate (DCPD) particles functionalized with di- or triethylene glycol dimethacrylate (DEGDMA or TEGDMA) on the degree of conversion (DC), post-gel shrinkage (PS), mechanical properties, and ion release of experimental composites. Four composites were prepared containing a BisGMA/TEGDMA matrix and 60 vol% of fillers. The positive control contained only barium glass fillers, while in the other composites 15 vol% of the barium was replaced by DCPD. Besides the functionalized particles, non-functionalized DCPD was also tested. DC after 24 h (n = 3) was determined by FTIR spectroscopy. The strain gage method was used to obtain PS 5 min after photoactivation (n = 5). Flexural strength and modulus (n = 10) were calculated based on the biaxial flexural test results, after specimen storage for 24 h or 60 days in water. The same storage times were used for fracture toughness testing (FT, n = 10). Calcium and phosphate release up to 60 days was quantified by ICP-OES (n = 3). Data were analyzed by ANOVA/Tukey test (alpha: 5%). Composites containing functionalized DCPD presented higher DC than the control (p < 0.001). The material containing DEGDMA-functionalized particles showed higher PS than the other composites (p < 0.001). After 60 days, only the composite with DEGDMA-functionalized DCPD presented fracture strength similar to the control, while for flexural modulus only the composite with TEGDMA-functionalized particles was lower than the control (p < 0.001). FT of all composites containing DCPD was higher than the control after 60 days (p < 0.005). Calcium release was higher for the composite with non-functionalized DCPD at 15 days and no significant reductions were observed for composites with functionalized DCPD during the observation period (p < 0.001). For all the tested composites, phosphate release was higher at 15 days than in the subsequent periods, and no difference among them was recorded at 45 and 60 days (p < 0.001). DCPD functionalization affected all the studied variables. The composite with DEGDMA-functionalized particles was the only material with strength similar to the control after 60 days in water; however, it also presented the highest shrinkage. The presence of DCPD improved FT, regardless of functionalization. DCPD functionalization reduced ion release only during the first 15 days. Copyright © 2018 Elsevier Ltd. All rights reserved.

In vitro antibacterial activity of a novel resin-based pulp capping material containing the quaternary ammonium salt MAE-DB and Portland cement.

PubMed

Yang, Yanwei; Huang, Li; Dong, Yan; Zhang, Hongchen; Zhou, Wei; Ban, Jinghao; Wei, Jingjing; Liu, Yan; Gao, Jing; Chen, Jihua

2014-01-01

Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC) and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB) and to evaluate its effects on Streptococcus mutans growth in vitro. The experimental material was prepared from a 2 : 1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4 : 3 : 1) containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal) served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs) and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on bacteria in solution. Therefore, this material shows promise as a pulp capping material for vital pulp preservation in the treatment of deep caries.

Release of TEGDMA from composite during the chewing situation.

PubMed

Durner, J; Glasl, B; Zaspel, J; Kunzelmann, K H; Hickel, R; Reichl, F X

2010-07-01

The aim of this study was to investigate the triethylene glycol (TEGDMA) elution kinetics from light-cured composite with and without chewing simulation over a time period of 86 h. An experimental composite with TEGDMA labeled with a tracer dose of 14C-TEGDMA was used. The material parameters were in the range of commercially available composites. The mastification was simulated with the Fatigue-machine and the MUC-3 chewing simulator. 14C was eluted to 2.55% of the applied 14C-TEGDMA dose within 86 h after chewing simulation with the Fatigue-machine and to 2.60% after chewing simulation with the MUC-3. Similar 14C-kinetic data were found for 14C-elution with and without chewing simulation with the Fatigue-machine and with MUC-3. During the first 26 h after the beginning of the experiments a linear 14C-elution kinetic was observed, followed by a second linear 14C-elution kinetic with a lower slope up to 86 h in both apparatus. It could be shown that chewing simulation has no significant (p<0.05) effect on the release of 14C-TEGDMA (and/or 14C-degradation products) from polymerized composites. Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of fiber diameter on flexural properties of fiber-reinforced composites.

PubMed

Rezvani, Mohammad Bagher; Atai, Mohammad; Hamze, Faeze

2013-01-01

Flexural strength (FS) is one of the most important properties of restorative dental materials which could be improved in fiber-reinforced composites (FRCs) by several methods including the incorporation of stronger reinforcing fibers. This study evaluates the influence of the glass fiber diameter on the FS and elastic modulus of FRCs at the same weight percentage. A mixture of 2,2-bis-[4-(methacryloxypropoxy)-phenyl]-propaneand triethyleneglycol dimethacrylate (60/40 by weight) was prepared as the matrix phase in which 0.5 wt. % camphorquinone and 0.5 wt. % N-N'-dimethylaminoethyl methacrylate were dissolved as photoinitiator system. Glass fibers with three different diameters (14, 19, and 26 μm) were impregnated with the matrix resin using a soft brush. The FRCs were inserted into a 2 × 2 × 25 mm3 mold and cured using a light curing unit with an intensity of ca. 600 mW/cm2 . The FS of the FRCs was measured in a three-point bending method. The elastic modulus was determined from the slope of the initial linear part of stress-strain curve. The fracture surface of the composites was observed using scanning electron microscopy to study the fiber-matrix interface. The results were analyzed and compared using one-way ANOVA and Tukey's post-hoc test. Although the FS increased as the diameter of fibers increased up to 19 μm (P < 0.05), no significant difference was observed between the composites containing fibers with diameters of 19 and 26 μm. The diameter of the fibers influences the mechanical properties of the FRCs.

Ionic liquid based multifunctional double network gel

NASA Astrophysics Data System (ADS)

Ahmed, Kumkum; Higashihara, Tomoya; Arafune, Hiroyuki; Kamijo, Toshio; Morinaga, Takashi; Sato, Takaya; Furukawa, Hidemitsu

2015-04-01

Gels are a promising class of soft and wet materials with diverse application in tissue engineering and bio-medical purpose. In order to accelerate the development of gels, it is required to synthesize multi-functional gels of high mechanical strength, ultra low surface friction and suitable elastic modulus with a variety of methods and new materials. Among many types of gel ionic gel made from ionic liquids (ILs) could be used for diverse applications in electrochemical devices and in the field of tribology. IL, a promising materials for lubrication, is a salt with a melting point lower than 100 °C. As a lubricant, ILs are characterized by an extremely low vapor pressure, high thermal stability and high ion conductivity. In this work a novel approach of making double network DN ionic gel using IL has been made utilizing photo polymerization process. A hydrophobic monomer Methyl methacrylate (MMA) has been used as a first network and a hydrophobic IL monomer, N,N-diethyl-N-(2-mthacryloylethyl)-N-methylammonium bistrifluoromethylsulfonyl)imide (DEMM-TFSI) has been used as a second network using photo initiator benzophenon and crosslinker triethylene glycol dimethacrylate (TEGDMA). The resulting DN ionic gel shows transparency, flexibility, high thermal stability, good mechanical toughness and low friction coefficient value which can be a potential candidate as a gel slider in different mechanical devices and can open a new area in the field of gel tribology.

Preparation of low shrinkage methacrylate-based resin system without Bisphenol A structure by using a synthesized dendritic macromer (G-IEMA).

PubMed

Yu, Biao; Liu, Fang; He, Jingwei

2014-07-01

With the growing attention on estrogenic effect of Bisphenol A (BPA), the application of BPA derivatives like Bis-GMA in dental materials has also been doubted. In this research, new BPA free dental resin systems were prepared with synthesized dendritic macromer G-IEMA, UDMA, and TEGDMA. Physicochemical properties, such as double bond conversion, polymerization shrinkage, flexural strength and modulus, fracture energy, water sorption and solubility of BPA free resin formulations were investigated. Bis-GMA/TEGDMA resin system was used as a control. Results showed that the prepared BPA free resins could have higher double bond conversion, comparable or lower polymerization shrinkage and water sorption, and lower water solubility, when compared with Bis-GMA/TEGDMA resin. Though flexural strength and modulus of prepared BPA free polymers were lower than those of Bis-GMA/TEGDMA polymer, BPA free polymers had higher fracture energies and showed plastic deformation prior to fracture, all of these two phenomena showed that BPA free polymers in this research might have higher fracture toughness which would be good for the service life of dental materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fabrication and evaluation of Bis-GMA/TEGDMA dental resins/composites containing halloysite nanotubes

PubMed Central

Chen, Qi; Zhao, Yong; Wu, Weidong; Xu, Tao; Fong, Hao

2012-01-01

Objective To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and the corresponding composites (with conventional glass filler)containing vari ed mass fractions of halloysite nanotubes (HNTs). Methods Three dispersion methods were studied to separate the silanized halloysite as individual HNTs and to uniformly distribute them into dental matrices. Photopolymerization induced volumetric shrinkage was measured by using a mercury dilatometer. Real time near infrared spectroscopy was adopted to study the degree of vinyl double bond conversion and the photopolymerization rate. Mechanical properties of the composites were tested by a universal mechanical testing machine. Analysis of Variance (ANOVA) was used for the statistical analysis of the acquired data. Morphologies of halloysite/HNTs and representative fracture surfaces of the reinforced dental resins/composites were examined by SEM and TEM. Results Impregnation of small mass fractions (e.g., 1% and 2.5%) of the silanized HNTs in Bis-GMA/TEGDMA dental resins/composites improved mechanical properties significantly; however; large mass fractions (e.g., 5%) of impregnation did not further improve the mechanical properties. The impregnation of HNTs into dental resins/composites could result in two opposite effects: the reinforcing effect due to the highly separated and uniformly distributed HNTs, and the weakening effect due to the formation of HNT agglomerates/particles. Significance Uniform distribution of a small amount of well-separated silanized HNTs into Bis-GMA/TEGDMA dental resins/composites could result in substantial improvements on mechanical properties. PMID:22796038

Fabrication and evaluation of Bis-GMA/TEGDMA dental resins/composites containing halloysite nanotubes.

PubMed

Chen, Qi; Zhao, Yong; Wu, Weidong; Xu, Tao; Fong, Hao

2012-10-01

To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and the corresponding composites (with conventional glass filler) containing varied mass fractions of halloysite nanotubes (HNTs). Three dispersion methods were studied to separate the silanized halloysite as individual HNTs and to uniformly distribute them into dental matrices. Photopolymerization induced volumetric shrinkage was measured by using a mercury dilatometer. Real time near infrared spectroscopy was adopted to study the degree of vinyl double bond conversion and the photopolymerization rate. Mechanical properties of the composites were tested by a universal mechanical testing machine. Analysis of variance (ANOVA) was used for the statistical analysis of the acquired data. Morphologies of halloysite/HNTs and representative fracture surfaces of the reinforced dental resins/composites were examined by SEM and TEM. Impregnation of small mass fractions (e.g., 1% and 2.5%) of the silanized HNTs in Bis-GMA/TEGDMA dental resins/composites improved mechanical properties significantly; however; large mass fractions (e.g., 5%) of impregnation did not further improve the mechanical properties. The impregnation of HNTs into dental resins/composites could result in two opposite effects: the reinforcing effect due to the highly separated and uniformly distributed HNTs, and the weakening effect due to the formation of HNT agglomerates/particles. Uniform distribution of a small amount of well-separated silanized HNTs into Bis-GMA/TEGDMA dental resins/composites could result in substantial improvements on mechanical properties. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Highly crosslinked polymeric monoliths for reversed-phase capillary liquid chromatography of small molecules.

PubMed

Liu, Kun; Tolley, H Dennis; Lee, Milton L

2012-03-02

Seven crosslinking monomers, i.e., 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA), neopentyl glycol dimethacrylate (NPGDMA), 1,5-pentanediol dimethacrylate (1,5-PDDMA), 1,6-hexanediol dimethacrylate (1,6-HDDMA), 1,10-decanediol dimethacrylate (1,10-DDDMA), and 1,12-dodecanediol dimethacrylate (1,12-DoDDMA), were used to synthesize highly cross-linked monolithic capillary columns for reversed-phase liquid chromatography (RPLC) of small molecules. Dodecanol and methanol were chosen as "good" and "poor" porogenic solvents, respectively, for these monoliths, and were investigated in detail to provide insight into the selection of porogen concentration using 1,12-DoDDMA. Isocratic elution of alkylbenzenes at a flow rate of 300 nL/min was conducted for all of the monoliths. Gradient elution of alkylbenzenes and alkylparabens provided high resolution separations. Optimized monoliths synthesized from all seven crosslinking monomers showed high permeability. Several of the monoliths demonstrated column efficiencies in excess of 50,000 plates/m. Monoliths with longer alkyl-bridging chains showed very little shrinking or swelling in solvents of different polarities. Column preparation was highly reproducible; the relative standard deviation (RSD) values (n=3) for run-to-run and column-to-column were less than 0.25% and 1.20%, respectively, based on retention times of alkylbenzenes. Copyright © 2012 Elsevier B.V. All rights reserved.

Dermal Sensitization Potential of Triethyleneglycol Dinitrate (TEGDN) in Guinea Pigs

DTIC Science & Technology

1989-01-01

mutagenicity assay, acute oral toxicity tests in rats and mice, acute dermal toxicity in rabbits, dermal and ocular irritation studies in rabbits, and...conditions: 85E0102 had diffuse tracheitis, mild endocarditis , mild hepatitis, and diffuse pigment granules in the small intestine; 85E0103 had mild...severe ulceration progressing to necrosis. Sensitization is manifested as indirect inflammation mediated by components of the immune system in

Mechanical properties of dental resin/composite containing urchin-like hydroxyapatite.

PubMed

Liu, Fengwei; Sun, Bin; Jiang, Xiaoze; Aldeyab, Sultan S; Zhang, Qinghong; Zhu, Meifang

2014-12-01

To investigate the reinforcing effect of urchin-like hydroxyapatite (UHA) in bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) dental resin (without silica nanoparticles) and dental composites (with silica nanoparticles), and explore the effect of HA filler morphologies and loadings on the mechanical properties. UHA was synthesized by a facile method of microwave irradiation and studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA). Mechanical properties of the dental resin composites containing silanized UHA were tested by a universal mechanical testing machine. Analysis of variance was used for the statistical analysis of the acquired data. The fracture morphologies of tested composites were observed by SEM. Composites with silanized irregular particulate hydroxyapatite (IPHA) and hydroxyapatite whisker (HW) were prepared for comparative studies. Impregnation of lower loadings (5 wt% and 10 wt%) of silanized UHA into dental resin (without silica nanoparticles) substantially improved the mechanical properties; higher UHA loadings (20 wt% and 30 wt%) of impregnation continuously improved the flexural modulus and microhardness, while the strength would no longer be increased. Compared with silanized IPHA and HW, silanized UHA consisting of rods extending radially from center were embedded into the matrix closely and well dispersed in the composite, increasing filler-matrix interfacial contact area and combination. At higher filler loadings, UHA interlaced together tightly without affecting the mobility of monomer inside, which might bear higher loads during fracture of the composite, leading to higher strengths than those of dental resins with IPHA and HW. Besides, impregnation of silanized UHA into dental composites (with silica nanoparticles) significantly improved the strength and modulus. UHA could serve as novel reinforcing HA filler to improve the mechanical properties of dental resin and dental composite.

Relationships between conversion, temperature and optical properties during composite photopolymerization.

PubMed

Howard, Benjamin; Wilson, Nicholas D; Newman, Sheldon M; Pfeifer, Carmem S; Stansbury, Jeffrey W

2010-06-01

Optical properties of composite restoratives, both cured and uncured, are of obvious importance in a procedure reliant on photoactivation, since they may affect light transmission and therefore materials conversion upon which mechanical properties and ultimate clinical performance are dependent. The objective of the present study was to evaluate simultaneous, real-time conversion, and the development of the temperature and optical properties. The dimethacrylate resin (Bis-GMA/TEGDMA 70/30mass%) was prepared at three filler loading (0, 35 or 70mass%: no fill, low and high fill, respectively) combined with three initiator concentrations (CQ/EDMAB: 0/0, 0.2/0.8 or 1.0/1.6mass%). Specimens were exposed to either low (50mWcm(-2)) or high (500mWcm(-2)) irradiance. Simultaneous conversion (near-IR peak area), temperature (thermocouple) and visible light transmission (UV-vis spectroscopy) measurements were conducted throughout the polymerization process. The refractive index of the resin rises linearly with conversion (r(2)=0.976), producing a refractive index match between resin/filler at approximately 58% conversion in these materials. The percentage increase in light transmission during conversion was greater for increasing filler levels. Higher CQ content led to maximum light transmission at slightly higher levels of conversion (60-65% and 50-55% for the high and low filled materials, respectively). The broad distribution of filler concentrations allows for the clinically relevant generalization that highly filled composites not only jeopardize absolute light transmission, conversion and depth of cure, but also demonstrate the complex interrelationship that exists between materials, processing conditions and the optical properties of dental composites. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Assessing the Penetrating Abilities of Experimental Preparation with Dental Infiltrant Features Using Optical Microscope: Preliminary Study.

PubMed

Skucha-Nowak, Małgorzata; Machorowska-Pieniążek, Agnieszka; Tanasiewicz, Marta

2016-01-01

The aim of the infiltration technique is to penetrate demineralized enamel with a low viscosity resin. Icon® (DMG) is the first ever and so far the only dental infiltrant. Bacteriostaticity is one of the properties that should be inherent in dental infiltrants, but Icon lacks this feature. The aim of the preliminary study was to properly choose a dye which would allow us to assess the penetrating abilities of our own, experimental preparation with features of a dental infiltrant with bacteriostatic properties and to compare using an optical microscope the depth of infiltration of the designed experimental preparation with the infiltrant available on the market. The preparation is supposed to infiltrate decalcified human enamel and be assessed with an optical microscope. Eosin, neutral fuchsine and methylene blue were added to experimental preparation with dental infiltrant features and to Icon® (DMG) in order to assess the depth of penetration of the experimental solution into the decalcified layers of enamel. The experimental solution mixes well with eosin, neutral fuchsine, and methylene blue. During the preliminary study, the authors concluded that the experimental solution mixes well with methylene blue, neutral fuchsine, and eosin. An addition of eosin to a preparation which infiltrates inner, demineralized enamel layers, facilitates the assessment of such a preparation with an optical microscope. A designed experimental solution with the main ingredients, i.e., 2-hydroxyethyl methacrylate (HEMA) and tetraethylene glycol dimethacrylate (TEGDMA) with a ratio of 75% to 25% penetrates the demineralized (decalcified) inner parts of the enamel and polymerizes when exposed to light. In order to assess the infiltration of the experimental solution into the demineralized enamel layers, it is required to improve the measurement techniques that utilize optical microscopy.

Development of novel self-healing and antibacterial dental composite containing calcium phosphate nanoparticles

PubMed Central

Wu, Junling; Weir, Michael D.; Melo, Mary Anne S.; Xu, Hockin H. K.

2015-01-01

Objectives Fracture and secondary caries are the primary reasons for dental restoration failure. The objective of this study was to develop a self-healing composite to heal cracks, while containing dimethylaminohexadecyl methacrylate (DMAHDM) for antibacterial function and nanoparticles of amorphous calcium phosphate (NACP) for remineralization. Methods Microcapsules were synthesized with poly(urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid. Composite contained 20 mass% of NACP and 35% glass fillers. In addition, composite contained 0%, 2.5%, 5%, 7.5%, or 10% of microcapsules. A single edge V-notched beam method measured fracture toughness (KIC) and self-healing efficiency. A dental plaque microcosm biofilm model was used to test the antibacterial properties. Results Incorporation of microcapsules up to 7.5% into the composite did not adversely affect the mechanical properties (p > 0.1). Successful self-healing was achieved, with KIC recovery of 65–81% (mean ± sd; n = 6) to regain the load-bearing capability after composite fracture. The self-healing DMAHDM-NACP composite displayed a strong antibacterial potency, inhibiting biofilm viability and lactic acid production, and reducing colony-forming units by 3–4 orders of magnitude, compared to control composite without DMAHDM. Conclusions A dental composite was developed with triple benefits of self-healing after fracture, antibacterial activity, and remineralization capability for the first time. Clinical significance The self-healing, antibacterial and remineralizing composite may be promising for tooth cavity restorations to combat bulk fracture and secondary caries. The method of using triple agents (self-healing microcapsules, DMAHDM, and NACP) may have wide applicability to other dental composites, adhesives, sealants and cements. PMID:25625674

pH-responsive and enzymatically-responsive hydrogel microparticles for the oral delivery of therapeutic proteins: Effects of protein size, crosslinking density, and hydrogel degradation on protein delivery.

PubMed

Koetting, Michael Clinton; Guido, Joseph Frank; Gupta, Malvika; Zhang, Annie; Peppas, Nicholas A

2016-01-10

Two potential platform technologies for the oral delivery of protein therapeutics were synthesized and tested. pH-responsive poly(itaconic acid-co-N-vinyl-2-pyrrolidone) (P(IA-co-NVP)) hydrogel microparticles were tested in vitro with model proteins salmon calcitonin, urokinase, and rituximab to determine the effects of particle size, protein size, and crosslinking density on oral delivery capability. Particle size showed no significant effect on overall delivery potential but did improve percent release of encapsulated protein over the micro-scale particle size range studied. Protein size was shown to have a significant impact on the delivery capability of the P(IA-co-NVP) hydrogel. We show that when using P(IA-co-NVP) hydrogel microparticles with 3 mol% tetra(ethylene glycol) dimethacrylate crosslinker, a small polypeptide (salmon calcitonin) loads and releases up to 45 μg/mg hydrogel while the mid-sized protein urokinase and large monoclonal antibody rituximab load and release only 19 and 24 μg/mg hydrogel, respectively. We further demonstrate that crosslinking density offers a simple method for tuning hydrogel properties to variously sized proteins. Using 5 mol% TEGDMA crosslinker offers optimal performance for the small peptide, salmon calcitonin, whereas lower crosslinking density of 1 mol% offers optimal performance for the much larger protein rituximab. Finally, an enzymatically-degradable hydrogels of P(MAA-co-NVP) crosslinked with the peptide sequence MMRRRKK were synthesized and tested in simulated gastric and intestinal conditions. These hydrogels offer ideal loading and release behavior, showing no degradative release of encapsulated salmon calcitonin in gastric conditions while yielding rapid and complete release of encapsulated protein within 1h in intestinal conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication and Evaluation of Bis-GMA/TEGDMA Dental Resins/Composites Containing Nano Fibrillar Silicate

PubMed Central

Tian, Ming; Gao, Yi; Liu, Yi; Liao, Yiliang; Hedin, Nyle E.; Fong, Hao

2008-01-01

Objective To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and composites (with conventional glass filler) with various mass fractions of nano fibrillar silicate (FS). Methods Three dispersion methods were studied to separate the silanized FS as nano-scaled single crystals and uniformly distribute them into dental matrices. The photo-curing behaviors of the Bis-GMA/TEGDMA/FS resins were monitored in situ by RT-NIR to study the photopolymerization rate and the vinyl double bond conversion. Mechanical properties (flexural strength, elastic modulus and work of fracture) of the nano FS reinforced resins/composites were tested, and Analysis of Variance (ANOVA) was used for the statistical analysis of the acquired data. The morphology of nano FS and the representative fracture surfaces of its reinforced resins/composites were examined by SEM/TEM. Results Impregnation of small mass fractions (1 % and 2.5 %) of nano FS into Bis-GMA/TEGDMA (50/50 mass ratio) dental resins/composites improved the mechanical properties substantially. Larger mass fraction of impregnation (7.5 %), however, did not further improve the mechanical properties (one way ANOVA, P > 0.05) and may even reduce the mechanical properties. The high degree of separation and uniform distribution of nano FS into dental resins/composites was a challenge. Impregnation of nano FS into dental resins/composites could result in two opposite effects: a reinforcing effect due to the highly separated and uniformly distributed nano FS single crystals, or a weakening effect due to the formation of FS agglomerates/particles. Significance Uniform distribution of highly separated nano FS single crystals into dental resins/composites could significantly improve the mechanical properties of the resins/composites. PMID:17572485

In vitro wear, surface roughness and hardness of propanal-containing and diacetyl-containing novel composites and copolymers based on bis-GMA analogs.

PubMed

Prakki, Anuradha; Cilli, Renato; Mondelli, Rafael Francisco Lia; Kalachandra, Sid

2008-03-01

To evaluate the effect of two additives, aldehyde or diketone, on the wear, roughness and hardness of bis-GMA-based composites/copolymers containing TEGDMA, propoxylated bis-GMA (CH(3)bis-GMA) or propoxylated fluorinated bis-GMA (CF(3)bis-GMA). Fifteen experimental composites and 15 corresponding copolymers were prepared combining bis-GMA and TEGDMA, CH(3)bis-GMA or CF(3)bis-GMA, with aldehyde (24 mol% and 32 mol%) or diketone (24 mol% and 32 mol%) totaling 30 groups. For composites, hybrid treated filler (barium aluminosilicate glass/pyrogenic silica; 60 wt%) was added to monomer mixtures. Photopolymerization was affected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Wear (W) test was conducted in a toothbrushing abrasion machine (n=6) and quantified using a profilometer. Surface roughness (R) changes, before and after abrasion test, were determined using a rugosimeter. Microhardness (H) measurements were performed for dry and wet samples using a Knoop microindenter (n=6). Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). Incorporation of additives led to improved W and H values for bis-GMA/TEGDMA and bis-GMA/CH(3)bis-GMA systems. Additives had no significant effect on the W and H changes of bis-GMA/CF(3)bis-GMA. With regard to R changes, additives produced decreased values for bis-GMA/CH(3)bis-GMA and bis-GMA/CF(3)bis-GMA composites. Bis-GMA/TEGDMA and bis-GMA/CH(3)bis-GMA copolymers with additives became smoother after abrasion test. The findings correlate with additives ability to improve degree of conversion of some composites/copolymers thereby enhancing mechanical properties.

Fabrication and evaluation of Bis-GMA/TEGDMA dental resins/composites containing nano fibrillar silicate.

PubMed

Tian, Ming; Gao, Yi; Liu, Yi; Liao, Yiliang; Hedin, Nyle E; Fong, Hao

2008-02-01

To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and composites (with conventional glass filler) with various mass fractions of nano fibrillar silicate (FS). Three dispersion methods were studied to separate the silanized FS as nano-scaled single crystals and uniformly distribute them into dental matrices. The photo-curing behaviors of the Bis-GMA/TEGDMA/FS resins were monitored in situ by RT-NIR to study the photopolymerization rate and the vinyl double bond conversion. Mechanical properties (flexural strength, elastic modulus and work-of-fracture) of the nano FS reinforced resins/composites were tested, and analysis of variance (ANOVA) was used for the statistical analysis of the acquired data. The morphology of nano FS and the representative fracture surfaces of its reinforced resins/composites were examined by SEM/TEM. Impregnation of small mass fractions (1% and 2.5%) of nano FS into Bis-GMA/TEGDMA (50/50 mass ratio) dental resins/composites improved the mechanical properties substantially. Larger mass fraction of impregnation (7.5%), however, did not further improve the mechanical properties (one way ANOVA, P>0.05) and may even reduce the mechanical properties. The high degree of separation and uniform distribution of nano FS into dental resins/composites was a challenge. Impregnation of nano FS into dental resins/composites could result in two opposite effects: a reinforcing effect due to the highly separated and uniformly distributed nano FS single crystals, or a weakening effect due to the formation of FS agglomerates/particles. Uniform distribution of highly separated nano FS single crystals into dental resins/composites could significantly improve the mechanical properties of the resins/composites.

High excimer-state emission of perylene bisimides and recognition of latent fingerprints.

PubMed

Wang, Ke-Rang; Yang, Zi-Bo; Li, Xiao-Liu

2015-04-07

High excimer-state emission in the H-type aggregate of a novel asymmetric perylene bisimide derivative, 6, with triethyleneglycol chains and lactose functionalization was achieved in water. Furthermore, its application for enhancing the visualization of transfer latent fingerprints from glass slides to the poly(vinylidene fluoride) (PVDF) membrane was explored, which showed clear images of the latent fingerprint in daylight and under 365 nm ultraviolet illumination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of viscosity and amine content on C==C conversion and color stability of experimental composites.

PubMed

Camargo, Fernanda Missio; Della Bona, Álvaro; Moraes, R R; Coutinho de Souza, C R; Schneider, Luis Felipe

2015-05-01

To investigate the influence of camphorquinone (CQ):amine ratio on the degree of CC conversion (DC) and color stability of experimental dental composites formulated with different co-monomer viscosities, indirectly determined by variations in the co-monomer ratios. Experimental composites were formulated in two different BisGMA:TEGDMA molar ratios (50:50 and 70:30). Viscosities were assessed with a viscometer. For each composite formulation, four different CQ:amine ratios were added: 1:1, 1:2, 1:3 or 1:4 mol%. Materials were loaded with 40 wt% of silanized glass particles. DC was determined by Fourier-transformed infrared spectroscopy with attenuated reflectance mode (ATR-FTIR). A spectrophotometer was used to measure the CIE L*a*b* color coordinates 24h after polymerization and after 2 months stored in water. Color changes (ΔE) were calculated. Data were statistically analyzed using analyses of variance (ANOVA), Tukey's and Student-t tests (α=0.05). The 50:50 BisGMA:TEGDMA co-monomer showed lower viscosity than 70:30. DC was affected by CQ:amine ratio, and not by the co-monomer viscosity, but the interaction between these two factors was significant. a* and b* coordinates were dependent on CQ:amine or BisGMA:TEGDMA ratios, while L* was not. b* values were directly related to the amount of amine in the formulation, regardless of co-monomer viscosity. ΔE was dependent on the amount of amine, but not on the viscosity of the material. DC was influenced by the CQ:amine ratio. The influence of viscosity on DC was dependent on the CQ:amine ratio and exhibited distinguished behavior. a* and b* coordinates were affected by CQ:amine and BisGMA:TEGDMA ratios. The color change (ΔE) was affected by CQ:amine ratio, but not by viscosity. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of increased exposure times on amount of residual monomer released from single-step self-etch adhesives.

PubMed

Altunsoy, Mustafa; Botsali, Murat Selim; Tosun, Gonca; Yasar, Ahmet

2015-10-16

The aim of this study was to evaluate the effect of increased exposure times on the amount of residual Bis-GMA, TEGDMA, HEMA and UDMA released from single-step self-etch adhesive systems. Two adhesive systems were used. The adhesives were applied to bovine dentin surface according to the manufacturer's instructions and were polymerized using an LED curing unit for 10, 20 and 40 seconds (n = 5). After polymerization, the specimens were stored in 75% ethanol-water solution (6 mL). Residual monomers (Bis-GMA, TEGDMA, UDMA and HEMA) that were eluted from the adhesives (after 10 minutes, 1 hour, 1 day, 7 days and 30 days) were analyzed by high-performance liquid chromatography (HPLC). The data were analyzed using 1-way analysis of variance and Tukey HSD tests. Among the time periods, the highest amount of released residual monomers from adhesives was observed in the 10th minute. There were statistically significant differences regarding released Bis-GMA, UDMA, HEMA and TEGDMA between the adhesive systems (p<0.05). There were no significant differences among the 10, 20 and 40 second polymerization times according to their effect on residual monomer release from adhesives (p>0.05). Increasing the polymerization time did not have an effect on residual monomer release from single-step self-etch adhesives.

Novel dental adhesive resin with crack self-healing, antimicrobial and remineralization properties.

PubMed

Yue, Shichao; Wu, Junling; Zhang, Qiang; Zhang, Ke; Weir, Michael D; Imazato, Satoshi; Bai, Yuxing; Xu, Hockin H K

2018-05-18

Secondary caries at the tooth-restoration margins is a primary reason for restoration failure. Cracks at the margins lead to leakage which can trap bacteria, producing acids to cause caries. To date, there has been no report on developing an adhesive resin that has self-healing, antibacterial and remineralizing capabilities. The objectives of this study were to: (1) develop the first self-healing adhesive with antimicrobial and remineralizing capabilities, and (2) investigate the effects of incorporating microcapsules, dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP) for the first time. Self-healing microcapsules were synthesized with poly(urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) as the healing liquid. The new adhesive contained 7.5% microcapsules, 10% DMAHDM and 20% NACP. A single edge V-notched beam (SEVNB) method was used to measure the fracture toughness K IC and the autonomous crack-healing efficiency. An oral plaque microcosm biofilm model was tested. The new self-healing, antimicrobial and remineralizing dental adhesive matched the dentin bond strength of a commercial control (p > 0.1). The new adhesive achieved successful crack-healing, with an excellent K IC recovery of 67%. The new adhesive had strong antimicrobial activity, reducing biofilm colony-forming units by four orders of magnitude, and reducing biofilm acid production to 1/100th that of biofilms on the commercial control resin. A self-healing adhesive with antibacterial and remineralizing capabilities was developed for the first time. Excellent dentin bond strength, autonomous crack-healing and K IC recovery, and strong anti-biofilm properties were achieved for the new adhesive resin. The novel method of using triple agents (self-healing microcapsules + DMAHDM + NACP) is promising for applications in dental adhesives, cements, sealants and composites to combat the two main challenges: fracture and secondary caries. Copyright © 2018 Elsevier Ltd. All rights reserved.

In-vitro investigations of a pH- and ionic-strength-responsive polyelectrolytic hydrogel using a piezoresistive microsensor

PubMed Central

Schulz, Volker; Guenther, Margarita; Gerlach, Gerald; Magda, Jules J.; Tathireddy, Prashant; Rieth, Loren; Solzbacher, Florian

2010-01-01

Environmental responsive or smart hydrogels show a volume phase transition due to changes of external stimuli such as pH or ionic strength of an ambient solution. Thus, they are able to convert reversibly chemical energy into mechanical energy and therefore they are suitable as sensitive material for integration in biochemical microsensors and MEMS devices. In this work, micro-fabricated silicon pressure sensor chips with integrated piezoresistors were used as transducers for the conversion of mechanical work into an appropriate electrical output signal due to the deflection of a thin silicon bending plate. Within this work two different sensor designs have been studied. The biocompatible poly(hydroxypropyl methacrylate-N,N-dimethylaminoethyl methacrylate-tetra-ethyleneglycol dimethacrylate) (HPMA-DMA-TEGDMA) was used as an environmental sensitive element in piezoresistive biochemical sensors. This polyelectrolytic hydrogel shows a very sharp volume phase transition at pH values below about 7.4 which is in the range of the physiological pH. The sensor's characteristic response was measured in-vitro for changes in pH of PBS buffer solution at fixed ionic strength. The experimental data was applied to the Hill equation and the sensor sensitivity as a function of pH was calculated out of it. The time-dependent sensor response was measured for small changes in pH, whereas different time constants have been observed. The same sensor principal was used for sensing of ionic strength. The time-dependent electrical sensor signal of both sensors was measured for variations in ionic strength at fixed pH value using PBS buffer solution. Both sensor types showed an asymmetric swelling behavior between the swelling and the deswelling cycle as well as different time constants, which was attributed to the different nature of mechanical hydrogel-confinement inside the sensor. PMID:21152365

Photopolymerization of N,N-dimethylaminobenzyl alcohol as amine co-initiator for light-cured dental resins.

PubMed

Schroeder, Walter F; Cook, Wayne D; Vallo, Claudia I

2008-05-01

The present study was carried out in order to assess the suitability of N,N-dimethylaminobenzyl alcohol (DMOH) as co-initiator of camphorquinone (CQ) and 1-phenyl-1,2-propanedione (PPD) in light-cured dental resins. DMOH was synthesized and used as co-initiator for the photopolymerization of a model resin based on {2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane} (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA). Experimental formulations containing CQ or PPD in combination with DMOH at different concentrations were studied. The photopolymerization was carried out by means of a commercial light-emitting diode (LED) curing unit. The evolution of double bonds consumption versus irradiation time was followed by near-infrared spectroscopy (NIR). The photon absorption efficiency (PAE) of the photopolymerization process was calculated from the spectral distribution of the LED unit and the molar absorption coefficient distributions of PPD and CQ. DMOH is an efficient photoreducer of CQ and PPD resulting in higher polymerization rate and higher double bond conversion compared with dimethylaminoethylmethacrylate. The PAE for PPD was higher than that for CQ. However, the polymerization initiated by PPD progressed at a lower rate and exhibited lower values of final conversion compared with the resins containing CQ. This observation indicates that the lower polymerization rate of the PPD/amine system should be explained in terms of the mechanism of generating primary radicals by PPD, which is less efficient compared with CQ. The DMOH/benzoyl peroxide redox system, has recently been proposed as a more biocompatible accelerator for the polymerization of bone cements based on poly(methyl methacrylate), because cytotoxity tests have demonstrated that DMOH possesses better biocompatibility properties compared with traditional tertiary amines. The results obtained in the present study reveal the suitability of the CQ/DMOH initiator system for the polymerization of light-cured dental composites.

Biodegradation of composite resin with ester linkages: identifying human salivary enzyme activity with a potential role in the esterolytic process.

PubMed

Cai, Kuihua; Delaviz, Yasaman; Banh, Michael; Guo, Yi; Santerre, J Paul

2014-08-01

The ester linkages contained within dental resin monomers (such as Bisphenol A-glycidylmethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA)) are susceptible to hydrolytic degradation by salivary esterases, however very little is known about the specific esterase activities implicated in this process. The objective of this work was to isolate and identify the dominant proteins from saliva that are associated with the esterase activities shown to be involved in the degradation of BisGMA. Human whole saliva was collected and processed prior to separation in a HiPrep 16/60 Sephacryl S-200 HR column. The fraction with the highest esterase activity was further separated by an anion exchange column (Mono-Q (10/100G)). Isolated fractions were then separated by gel electrophoresis, and compared to a common bench marker esterase, cholesterol esterase (CE), and commercial albumin which has been reported to express esterase activity. Proteins suspected of containing esterase activity were analyzed by Mass Spectroscopy (MS). Commercially available proteins, similar to the salivary esterase proteins identified by MS, were used to replicate the enzymatic complexes and confirm their degradation activity with respect to BisGMA. MS data suggested that the enzyme fraction with the highest esterase activity was contained among a group of proteins consisting of albumin, Zn-α2-glycoprotein, α-amylase, TALDO1 protein, transferrin, lipocalin2, and prolactin-induced protein. Studies concluded that the main esterase bands on the gels in each fraction did not overlap with CE activity, and that albumin activity emerged as a lead candidate with significant esterase activity relative to BisGMA degradation, particularly when it formed a complex with Zn-α2-glycoprotein, under slightly basic conditions. These enzyme complexes can be used as a physiologically relevant formulation to test the biostability of composite resins. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Conjugation of diisocyanate side chains to dimethacrylate reduces polymerization shrinkage and increases the hardness of composite resins.

PubMed

Jan, Yih-Dean; Lee, Bor-Shiunn; Lin, Chun-Pin; Tseng, Wan-Yu

2014-04-01

Polymerization shrinkage is one of the main causes of dental restoration failure. This study tried to conjugate two diisocyanate side chains to dimethacrylate resins in order to reduce polymerization shrinkage and increase the hardness of composite resins. Diisocyanate, 2-hydroxyethyl methacrylate, and bisphenol A dimethacrylate were reacted in different ratios to form urethane-modified new resin matrices, and then mixed with 50 wt.% silica fillers. The viscosities of matrices, polymerization shrinkage, surface hardness, and degrees of conversion of experimental composite resins were then evaluated and compared with a non-modified control group. The viscosities of resin matrices increased with increasing diisocyanate side chain density. Polymerization shrinkage and degree of conversion, however, decreased with increasing diisocyanate side chain density. The surface hardness of all diisocyanate-modified groups was equal to or significantly higher than that of the control group. Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins. Copyright © 2012. Published by Elsevier B.V.

Color and translucency in silorane-based resin composite compared to universal and nanofilled composites.

PubMed

Pérez, María M; Ghinea, Razvan; Ugarte-Alván, Laura I; Pulgar, Rosa; Paravina, Rade D

2010-01-01

The purpose of this study was to determine the optical properties, color and translucency, of the new silorane-based resin composite and to compare it to universal dimethacrylate-based composites. Six dimethacrylate-based resin composites and one silorane-based resin composite (all A2 shade) were studied. Color of non-polymerized and polymerized composites was measured against white and black backgrounds using a spectroradiometer. Changes in color (ΔE*(ab)), translucency (ΔTP) and color coordinates (ΔL*, Δa* and Δb*) were calculated for each resin composite. Results were evaluated using a one-way ANOVA, a Tukey's test and a t-test. The polymerization-dependent ΔE*(ab) ranged from 4.7 to 9.1, with the smallest difference for the silorane-based resin composite. The color changes of silorane-based composite were due to the changes of coordinates Δa* and Δb*. However, for the dimethacrylate-based composites, the color changes mainly originated by ΔL*and Δb*. The silorane composite exhibited the smallest TP values. Tukey's test confirmed significant statistical differences (p<0.05) between mean TP values of Filtek Silorane and each brand of dimethacrylate-based composites before and after polymerization. The new silorane-based restorative system showed different optical properties compared to clinically successful dimethacrylate composites. The silorane composite exhibited better polymerization-dependent chromatic stability, and a lower translucency compared to other tested products. Copyright © 2010 Elsevier Ltd. All rights reserved.

Development of the foremost light-curable calcium-silicate MTA cement as root-end in oral surgery. Chemical-physical properties, bioactivity and biological behavior.

PubMed

Gandolfi, Maria Giovanna; Taddei, Paola; Siboni, Francesco; Modena, Enrico; Ciapetti, Gabriela; Prati, Carlo

2011-07-01

An innovative light-curable calcium-silicate cement containing a HEMA-TEGDMA-based resin (lc-MTA) was designed to obtain a bioactive fast setting root-end filling and root repair material. lc-MTA was tested for setting time, solubility, water absorption, calcium release, alkalinizing activity (pH of soaking water), bioactivity (apatite-forming ability) and cell growth-proliferation. The apatite-forming ability was investigated by micro-Raman, ATR-FTIR and ESEM/EDX after immersion at 37°C for 1-28 days in DPBS or DMEM+FBS. The marginal adaptation of cement in root-end cavities of extracted teeth was assessed by ESEM/EDX, and the viability of Saos-2 cell on cements was evaluated. lc-MTA demonstrated a rapid setting time (2min), low solubility, high calcium release (150-200ppm) and alkalinizing power (pH 10-12). lc-MTA proved the formation of bone-like apatite spherulites just after 1 day. Apatite precipitates completely filled the interface porosities and created a perfect marginal adaptation. lc-MTA allowed Saos-2 cell viability and growth and no compromising toxicity was exerted. HEMA-TEGDMA creates a polymeric network able to stabilize the outer surface of the cement and a hydrophilic matrix permeable enough to allow water absorption. SiO(-)/Si-OH groups from the mineral particles induce heterogeneous nucleation of apatite by sorption of calcium and phosphate ions. Oxygen-containing groups from poly-HEMA-TEGDMA provide additional apatite nucleating sites through the formation of calcium chelates. The strong novelty was that the combination of a hydraulic calcium-silicate powder and a poly-HEMA-TEGDMA hydrophilic resin creates the conditions (calcium release and functional groups able to chelate Ca ions) for a bioactive fast setting light-curable material for clinical applications in dental and maxillofacial surgery. The first and unique/exclusive light-curable calcium-silicate MTA cement for endodontics and root-end application was created, with a potential strong impact on surgical procedures. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Shrinkage strain-rates of dental resin-monomer and composite systems.

PubMed

Atai, Mohammad; Watts, David C; Atai, Zahra

2005-08-01

The purpose of this study was to investigate the shrinkage strain rate of different monomers, which are commonly used in dental composites and the effect of monomer functionality and molecular mass on the rate. Bis-GMA, TEGDMA, UDMA, MMA, HEMA, HPMA and different ratios of Bis-GMA/TEGDMA were mixed with Camphorquinone and Dimethyl aminoethyle methacrylate as initiator system. The shrinkage strain of the samples photopolymerised at Ca. 550 mW/cm2 and 23 degrees C was measured using the bonded-disk technique of Watts and Cash (Meas. Sci. Technol. 2 (1991) 788-794), and initial shrinkage-strain rates were obtained by numerical differentiation. Shrinkage-strain rates rose rapidly to a maximum, and then fell rapidly upon vitrification. Strain and initial strain rate were dependent upon monomer functionality, molecular mass and viscosity. Strain rates were correlated with Bis-GMA in Bis-GMA/TEGDMA mixtures up to 75-80 w/w%, due to the higher molecular mass of Bis-GMA affecting termination reactions, and then decreased due to its higher viscosity affecting propagation reactions. Monofunctional monomers exhibited lower rates. UDMA, a difunctional monomer of medium viscosity, showed the highest shrinkage strain rate (P < 0.05). Shrinkage strain rate, related to polymerization rate, is an important factor affecting the biomechanics and marginal integrity of composites cured in dental cavities. This study shows how this is related to monomer molecular structure and viscosity. The results are significant for the production, optimization and clinical application of dental composite restoratives.

Highly conductive solid polymer electrolyte membranes based on polyethylene glycol-bis-carbamate dimethacrylate networks

NASA Astrophysics Data System (ADS)

Fu, Guopeng; Dempsey, Janel; Izaki, Kosuke; Adachi, Kaoru; Tsukahara, Yasuhisa; Kyu, Thein

2017-08-01

In an effort to fabricate highly conductive, stable solid-state polymer electrolyte membranes (PEM), polyethylene glycol bis-carbamate (PEGBC) was synthesized via condensation reaction between polyethylene glycol diamine and ethylene carbonate. Subsequently, dimethacrylate groups were chemically attached to both ends of PEGBC to afford polyethylene glycol-bis-carbamate dimethacrylate (PEGBCDMA) precursor having crosslinking capability. The melt-mixed ternary mixtures consisting of PEGBCDMA, succinonitrile plasticizer, and lithium trifluorosulphonyl imide salt were completely miscible in a wide compositional range. Upon photo-crosslinking, the neat PEGBCDMA network was completely amorphous exhibiting higher tensile strength, modulus, and extensibility relative to polyethylene glycol diacrylate (PEGDA) counterpart. Likewise, the succinonitrile-plasticized PEM network containing PEGBCDMA remained completely amorphous and transparent upon photo-crosslinking, showing superionic conductivity, improved thermal stability, and superior tensile properties with improved capacity retention during charge/discharge cycling as compared to the PEGDA-based PEM.

Comparison of polymer-based temporary crown and fixed partial denture materials by diametral tensile strength.

PubMed

Ha, Seung-Ryong; Yang, Jae-Ho; Lee, Jai-Bong; Han, Jung-Suk; Kim, Sung-Hun

2010-03-01

The purpose of this study was to investigate the diametral tensile strength of polymer-based temporary crown and fixed partial denture (FPD) materials, and the change of the diametral tensile strength with time. One monomethacrylate-based temporary crown and FPD material (Trim) and three dimethacrylate-based ones (Protemp 3 Garant, Temphase, Luxtemp) were investigated. 20 specimens (ø 4 mm × 6 mm) were fabricated and randomly divided into two groups (Group I: Immediately, Group II: 1 hour) according to the measurement time after completion of mixing. Universal Testing Machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed using one-way ANOVA, the multiple comparison Scheffe test and independent sample t test (α = 0.05). Trim showed severe permanent deformation without an obvious fracture during loading at both times. There were statistically significant differences among the dimethacrylate-based materials. The dimethacrylate-based materials presented an increase in strength from 5 minutes to 1 hour and were as follows: Protemp 3 Garant (23.16 - 37.6 MPa), Temphase (22.27 - 28.08 MPa), Luxatemp (14.46 - 20.59 MPa). Protemp 3 Garant showed the highest value. The dimethacrylate-based temporary materials tested were stronger in diametral tensile strength than the monomethacrylate-based one. The diametral tensile strength of the materials investigated increased with time.

Sol-gel-graphene-based fabric-phase sorptive extraction for cow and human breast milk sample cleanup for screening bisphenol A and residual dental restorative material before analysis by HPLC with diode array detection.

PubMed

Samanidou, Victoria; Filippou, Olga; Marinou, Eirini; Kabir, Abuzar; Furton, Kenneth G

2017-06-01

Fabric-phase sorptive extraction has already been recognized as a simple and green alternative to the conventional sorbent-based sorptive microextraction techniques, using hybrid organic-inorganic sorbent coatings chemically bonded to a flexible fabric surface. Herein, we have investigated the synergistic combination of the advanced material properties offered by sol-gel graphene sorbent and the simplicity of Fabric phase sorptive extraction approach in selectively extracting bisphenol A and residual monomers including bisphenol A glycerolatedimethacrylate, urethane dimethacrylate, and triethylene glycol dimethacrylate derived dental restorative materials from cow and human breast milk samples. Different coatings were evaluated. Final method development employed sol-gel graphene coated media. The main experimental parameters influencing extraction of the compounds, such as sorbent chemistry used, sample loading conditions, elution solvent, sorption stirring time, elution time, impact of protein precipitation, amount of sample, and matrix effect, were investigated and optimized. Absolute recovery values from standard solutions were 50% for bisphenol A, 78% for T triethylene glycol dimethacrylate, 110% for urethane dimethacrylate, and 103% for bisphenol A glycerolatedimethacrylate, while respective absolute recovery values from milk were 30, 52, 104, and 42%. Method validation was performed according to European Decision 657/2002/EC in terms of selectivity, sensitivity, linearity, accuracy, and precision. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An in vitro study of anticariogenic compounds incorporated into Bis-GMA/TEGDMA copolymer

NASA Astrophysics Data System (ADS)

Pilly Yadaiah, Vinay Kumar

Composite resins continue to evolve and are increasingly favoured by the people. However, drawbacks such as decreased longevity, secondary caries and costs make choosing composites a dilemma. This study evaluated drug release, inhibitory growth against Streptococcus mutans and drug stability of epigallocatechin-gallate (EGCg) incorporated into dental copolymer compared to resins containing chlorhexidine (CHX). Resin discs (5mm x 3mm) were prepared from 70 mol% Bis-GMA and 30 mol% TEGDMA comonomers containing: placebo, CHX and EGCg. Two corresponding concentrations in weight% of each drug for 0.5 and 1.0 x MIC were incorporated into paste resins and tested at time points: 24 hours, 7 days, 30 days, 60 days and 90 days. There is a significant difference in the 90 days drug delivery and bacterial inhibition among different drugs and drug ratios, which showed stability after 90 days. The results indicate that drug-based composites may reduce bacterial growth, which may improve its longevity.

Radiation-grafting of ethylene glycol dimethacrylate (EGDMA) and glycidyl methacrylate (GMA) onto silicone rubber

NASA Astrophysics Data System (ADS)

Flores-Rojas, G. G.; Bucio, E.

2016-10-01

Silicone rubber (SR) was modified with a graft of ethylene glycol dimethacrylate (EGDMA) and glycidyl methacrylate (GMA) using either gamma-radiation or azobisisobutyronitrile (AIBN). The graft efficiency was evaluated as a function of monomer concentration, absorbed dose, reaction temperature, and concentration of AIBN. The hydrophilicity of the grafted films was measured by contact angle and their equilibrium swelling time in ethanol. Additional characterization by infrared (FTIR-ATR) spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is also reported.

Triethylene Glycol Up-Regulates Virulence-Associated Genes and Proteins in Streptococcus mutans.

PubMed

Sadeghinejad, Lida; Cvitkovitch, Dennis G; Siqueira, Walter L; Santerre, J Paul; Finer, Yoav

2016-01-01

Triethylene glycol dimethacrylate (TEGDMA) is a diluent monomer used pervasively in dental composite resins. Through hydrolytic degradation of the composites in the oral cavity it yields a hydrophilic biodegradation product, triethylene glycol (TEG), which has been shown to promote the growth of Streptococcus mutans, a dominant cariogenic bacterium. Previously it was shown that TEG up-regulated gtfB, an important gene contributing to polysaccharide synthesis function in biofilms. However, molecular mechanisms related to TEG's effect on bacterial function remained poorly understood. In the present study, S. mutans UA159 was incubated with clinically relevant concentrations of TEG at pH 5.5 and 7.0. Quantitative real-time PCR, proteomics analysis, and glucosyltransferase enzyme (GTF) activity measurements were employed to identify the bacterial phenotypic response to TEG. A S. mutans vicK isogenic mutant (SMΔvicK1) and its associated complemented strain (SMΔvicK1C), an important regulatory gene for biofilm-associated genes, were used to determine if this signaling pathway was involved in modulation of the S. mutans virulence-associated genes. Extracted proteins from S. mutans biofilms grown in the presence and absence of TEG were subjected to mass spectrometry for protein identification, characterization and quantification. TEG up-regulated gtfB/C, gbpB, comC, comD and comE more significantly in biofilms at cariogenic pH (5.5) and defined concentrations. Differential response of the vicK knock-out (SMΔvicK1) and complemented strains (SMΔvicK1C) implicated this signalling pathway in TEG-modulated cellular responses. TEG resulted in increased GTF enzyme activity, responsible for synthesizing insoluble glucans involved in the formation of cariogenic biofilms. As well, TEG increased protein abundance related to biofilm formation, carbohydrate transport, acid tolerance, and stress-response. Proteomics data was consistent with gene expression findings for the selected genes. These findings demonstrate a mechanistic pathway by which TEG derived from commercial resin materials in the oral cavity promote S. mutans pathogenicity, which is typically associated with secondary caries.

Triethylene Glycol Up-Regulates Virulence-Associated Genes and Proteins in Streptococcus mutans

PubMed Central

Sadeghinejad, Lida; Cvitkovitch, Dennis G.; Siqueira, Walter L.; Santerre, J. Paul; Finer, Yoav

2016-01-01

Triethylene glycol dimethacrylate (TEGDMA) is a diluent monomer used pervasively in dental composite resins. Through hydrolytic degradation of the composites in the oral cavity it yields a hydrophilic biodegradation product, triethylene glycol (TEG), which has been shown to promote the growth of Streptococcus mutans, a dominant cariogenic bacterium. Previously it was shown that TEG up-regulated gtfB, an important gene contributing to polysaccharide synthesis function in biofilms. However, molecular mechanisms related to TEG’s effect on bacterial function remained poorly understood. In the present study, S. mutans UA159 was incubated with clinically relevant concentrations of TEG at pH 5.5 and 7.0. Quantitative real-time PCR, proteomics analysis, and glucosyltransferase enzyme (GTF) activity measurements were employed to identify the bacterial phenotypic response to TEG. A S. mutans vicK isogenic mutant (SMΔvicK1) and its associated complemented strain (SMΔvicK1C), an important regulatory gene for biofilm-associated genes, were used to determine if this signaling pathway was involved in modulation of the S. mutans virulence-associated genes. Extracted proteins from S. mutans biofilms grown in the presence and absence of TEG were subjected to mass spectrometry for protein identification, characterization and quantification. TEG up-regulated gtfB/C, gbpB, comC, comD and comE more significantly in biofilms at cariogenic pH (5.5) and defined concentrations. Differential response of the vicK knock-out (SMΔvicK1) and complemented strains (SMΔvicK1C) implicated this signalling pathway in TEG-modulated cellular responses. TEG resulted in increased GTF enzyme activity, responsible for synthesizing insoluble glucans involved in the formation of cariogenic biofilms. As well, TEG increased protein abundance related to biofilm formation, carbohydrate transport, acid tolerance, and stress-response. Proteomics data was consistent with gene expression findings for the selected genes. These findings demonstrate a mechanistic pathway by which TEG derived from commercial resin materials in the oral cavity promote S. mutans pathogenicity, which is typically associated with secondary caries. PMID:27820867

High elastic modulus nanopowder reinforced resin composites for dental applications

NASA Astrophysics Data System (ADS)

Wang, Yijun

2007-12-01

Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus <15 GPa. Chemical additives can also effectively raise the hardness to as much as 1.34 GPa. Besides>alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with effective coupling agents and higher filler loading, viscous flow can be greatly decreased due to the attenuation of mobility of polymer chains. Complementary studies indicate that our resin composites are promising for the proposed applications as a stiff support to all-ceramic crowns.

In-situ polymerized PLOT columns III: divinylbenzene copolymers and dimethacrylate homopolymers

NASA Technical Reports Server (NTRS)

Shen, T. C.; Fong, M. M.

1994-01-01

Studies of divinylbenzene copolymers and dimethacrylate homopolymers indicate that the polymer pore size controls the separation of water and ammonia on porous-layer-open-tubular (PLOT) columns. To a lesser degree, the polarity of the polymers also affects the separation of a water-ammonia gas mixture. Our results demonstrate that the pore size can be regulated by controlling the cross-linking density or the chain length between the cross-linking functional groups. An optimum pore size will provide the best separation of water and ammonia.

Development and testing of novel bisphenol A-free adhesives for lingual fixed retainer bonding.

PubMed

Iliadi, Anna; Eliades, Theodore; Silikas, Nick; Eliades, George

2017-02-01

To comparatively evaluate the properties of two BPA-free experimental adhesives (EXA, EXB) for lingual fixed retainer bonding versus a commercially available reference material (Transbond LR-TLR) based on BPA-compound. The experimental materials were a flowable 60 per cent glass filler-filled UEDMA/TEGDMA flowable composite (EXB) and a 70 per cent glass filler-filled paste composite with PCDMA/UEDMA/TEGDMA co-monomers. The properties tested were degree of conversion (DC%), mechanical properties (Martens hardness-MH, elastic modulus-E IT , elastic index-n IT ), effect of prolonged (6 months) water storage (changes in Vickers microhardness-VHN) and pull-out strength employing a multi-stranded wire. EXB showed the highest DC% (63.6 per cent), followed by EXA (50.5 per cent) and TRL (44.1 per cent), with all means differences being statistically significant (P < 0.05). The statistical rankings of MH (MPa) and E IT (GPa) means were TLR (76.1MPa; 17.3GPa) > EXA (53MPa; 12.9GPa) > EXB (12.9MPa; 6.7GPa), whereas for n IT, EXB (40 per cent) > EXA (34.9 per cent), TLR (33.6 per cent). All materials were affected by prolonged water storage with significant differences among them in VHN. TLR was the most affected material (ΔVHN = -11 per cent), followed by EXA (ΔVHN = -6.8 per cent) and EXB (ΔVHN = -4.2 per cent). No statistically significant differences were found in the pull-out strength testing (24-24.2 N range) and failure mode (70-77 per cent mixed). Considering the differences between the two experimental materials, it may be concluded that the material containing the PCDMA/UEDMA/TEGDMA co-monomers may be used as an alternative to the control. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

New water-soluble metal working fluids additives from phosphonic acid derivatives for aluminum alloy materials.

PubMed

Kohara, Ichitaro; Tomoda, Hideyuki; Watanabe, Shoji

2007-01-01

Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short paper describes properties of new additives for water-soluble cutting fluids for aluminum alloy materials. Some alkyldiphosphonic acids were prepared with known method. Amine salts of these phosphonic acids showed anti-corrosion property for aluminum alloy materials. However, they have no hard water tolerance. Monoesters of octylphosphonic acid were prepared by the reaction of octylphosphonic acid dichloride with various alcohols in the presence of triethylamine. Amine salts of monoester of octylphosphonic acid with diethyleneglycol monomethyl ether, ethyleneglycol monomethyl ether and triethyleneglycol monomethyl ether showed both of a good anti-corrosion property for aluminum alloy materials and hard water tolerance.

Viscoelastic stability of resin-composites aged in food-simulating solvents.

PubMed

Marghalani, Hanadi Y; Watts, David C

2013-09-01

To study time-dependent viscoelastic deformation (creep and recovery) of resin-composites, after conditioning in food-simulating solvents, under a compressive stress at 37°C. Five dimethacrylate-based composites: (Spectrum TPH, Premise Body, Tetric Ceram HB, Filtek P60, X-tra fil), and two Ormocers (Experimental Ormocer V 28407, Admira) were studied. Three groups of cylindrical specimens (4mm×6mm) were prepared and then conditioned in 3 solvents: methyl ethyl ketone (MEK), ethanol, and water for 1 month at 37°C. The compressive creep-strain under 35MPa in 37°C water was recorded continuously for 2h and then the unloaded recovery-strain was monitored for another 2h. The data were analyzed by one-way ANOVA and Bonferroni's test. The materials all exhibited classic creep and recovery curves, with most parameters being significantly different (p<0.0001) for each solvent condition. All materials showed lower creep-strain in water than in ethanol or MEK solvents. Maximum creep-strain and permanent-set gave negative linear-regression (r(2)>0.98) with logarithm of the solvent solubility-parameter. The % mean (SD) creep-strain ranged from a minimum of 0.82 (0.01) for the Exp. Ormocer in water to the maximum of 4.19 (0.30) for Admira in MEK. Similar trends were found for permanent-set. The dimethacrylate-based composites behaved as an intermediate group, apart from X-tra fil that had similar stability to the Exp. Ormocer. The viscoelastic stability (low creep and permanent-set) of the Exp. Ormocer, compared to many dimethacrylate-based composites, in food-simulating solvents may be due to its diluent-free formulation. This was closely matched by a highly-filled dimethacrylate material (X-tra fil). Copyright © 2013 Academy of Dental Materials. All rights reserved.

Photopolymerization of highly filled dimethacrylate-based composites using Type I or Type II photoinitiators and varying co-monomer ratios.

PubMed

Randolph, Luc D; Steinhaus, Johannes; Möginger, Bernhard; Gallez, Bernard; Stansbury, Jeffrey; Palin, William M; Leloup, Gaëtane; Leprince, Julian G

2016-02-01

The use of a Type I photoinitiator (monoacylphosphine oxide, MAPO) was described as advantageous in a model formulation, as compared to the conventional Type II photoinitiator (Camphorquinone, CQ). The aim of the present work was to study the kinetics of polymerization of various composite mixtures (20-40-60-80 mol%) of bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (BisGMA/TegDMA) containing either CQ or MAPO, based on real-time measurements and on the characterization of various post-cure characteristics. Polymerization kinetics were monitored by Fourier-transform near-infrared spectroscopy (FT-NIRS) and dielectric analysis (DEA). A range of postcure properties was also investigated. FT-NIRS and DEA proved complementary to follow the fast kinetics observed with both systems. Autodecceleration occurred after ≈1 s irradiation for MAPO-composites and ≈5-10 s for CQ-composites. Conversion decreased with increasing initial viscosity for both photoinitiating systems. However despite shorter light exposure (3s for MAPO vs 20s for CQ-composites), MAPO-composites yielded higher conversions for all co-monomer mixtures, except at 20 mol% BisGMA, the less viscous material. MAPO systems were associated with increased amounts of trapped free radicals, improved flexural strength and modulus, and reduced free monomer release for all co-monomer ratios, except at 20 mol% BisGMA. This work confirms the major influence of the initiation system both on the conversion and network cross-linking of highly-filled composites, and further highlights the advantages of using MAPO photoinitiating systems in highly-filled dimethacrylate-based composites provided that sufficient BisGMA content (>40 mol%) and adapted light spectrum are used. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations.

PubMed

Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi Chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

2017-01-01

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05. Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001). Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001). In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001). Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations

PubMed Central

Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

2017-01-01

Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P < 0.05. Results. The maximum and minimum gaps were detected in groups 1-A and 2-B, respectively. The effects of composite resin type, preheating and interactive effect of these variables on gap formation were significant (P<0.001). Post-hoc Tukey tests showed greater gap in dimethacrylate compared to silorane composite resins (P< 0.001). In each group, gap values were greater in composite resins at room temperature compared to composite resins after 40 preheating cycles (P<0.001). Conclusion. Gap formation at the gingival margins of Class V cavities decreased due to preheating of both composite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation. PMID:28413594

Radiation synthesis of poly[(dimethylaminoethyl methacrylate)-co-(ethyleneglycol dimethacrylate)] hydrogels and its application as a carrier for anticancer delivery

NASA Astrophysics Data System (ADS)

Mazied, Nabila A.; Ismail, Sahar A.; Abou Taleb, Manal F.

2009-11-01

The use of hydrogels as carriers for anticancer delivery has been a subject of significant recent research. In our recent work, we have shown that diffusion-controlled delivery of flutamide from hydrogels containing poly (dimethylaminoethyl methacrylate (DMAEMA)/ethyleneglycol dimethacrylate (EGDMA)) can be possible and controlled by the three-dimensional structure. Hydrogels based essentially on dimethylaminoethyl methacrylate and different ratios of ethyleneglycol dimethacrylate monomers were synthesized using gamma radiation copolymerization. The influence of copolymer composition and pH value of the surrounding medium on swelling behavior into the glassy polymer were discussed. The results showed that the ratio of EGDMA in the comonomer feeding solution has a great effect on the gel fraction and water content in the final hydrogel. In this regard, it was observed that the increase of EGDMA ratio decreased these properties. The ability of the prepared copolymer to be used as drug carrier for anticancer drug-delivery system was estimated using flutamide as a model drug. In vitro drug-release studies in different buffer solutions show that the basic parameters affecting the drug release behavior of hydrogel are the pH of the solution and DMAEMA content of hydrogel.

Dimethacrylate network formation and polymer property evolution as determined by the selection of monomers and curing conditions

PubMed Central

Stansbury, Jeffrey W.

2011-01-01

Objectives This overview is intended to highlight connections between monomer structure and the development of highly crosslinked photopolymer networks including the conversion dependent properties of shrinkage, modulus and stress. Methods A review is provided that combines the polymer science and dental materials literature along with examples of relevant experimental results, which include measurements of reaction kinetics, photorheology as well as polymerization shrinkage and stress. Results While new monomers are continually under development for dental materials applications, mixtures of dimethacrylate monomers persist as the most common form of dental resins used on composite restorative materials. Monomer viscosity and reaction potential is derived from molecular structure and by employing real-time near-infrared spectroscopic techniques, the development of macromolecular networks is linked to the evolution of polymerization shrinkage (measured by linometer), modulus (measured by photorheometer), and stress (measured by tensometer). Relationships between the respective polymer properties are examined. Significance Through a better understanding of the polymer network formation and property development processes using conventional dimethacrylate monomer formulations, the rational design of improved materials is facilitated with the ultimate goal of achieving dental polymers that deliver enhanced clinical outcomes. PMID:22192248

A novel hydrogel based piezoresistive pressure sensor platform for chemical sensing

NASA Astrophysics Data System (ADS)

Orthner, Michael P.

New hydrogel-based micropressure sensor arrays for use in the fields of chemical sensing, physiological monitoring, and medical diagnostics are developed and demonstrated. This sensor technology provides reliable, linear, and accurate measurements of hydrogel swelling pressures, a function of ambient chemical concentrations. For the first time, perforations were implemented into the pressure sensors piezoresistive diaphragms, used to simultaneously increase sensor sensitivity and permit diffusion of analytes into the hydrogel cavity. It was shown through analytical and numerical (finite element) methods that pore shape, location, and size can be used to modify the diaphragm mechanics and concentrate stress within the piezoresistors, thus improving electrical output (sensitivity). An optimized pore pattern was chosen based on these numerical calculations. Fabrication was performed using a 14-step semiconductor fabrication process implementing a combination of potassium hydroxide (KOH) and deep reactive ion etching (DRIE) to create perforations. The sensor arrays (2x2) measure approximately 3 x 5 mm2 and used to measure full scale pressures of 50, 25, and 5 kPa, respectively. These specifications were defined by the various swelling pressures of ionic strength, pH and glucose specific hydrogels that were targeted in this work. Initial characterization of the sensor arrays was performed using a custom built bulge testing apparatus that simultaneously measured deflection (optical profilometry), pressure, and electrical output. The new perforated diaphragm sensors were found to be fully functional with sensitivities ranging from 23 to 252 muV/V-kPa with full scale output (FSO) ranging from 5 to 80 mV. To demonstrate proof of concept, hydrogels sensitive to changes in ionic strength were synthesized using hydroxypropyl-methacrylate (HPMA), N,N-dimethylaminoethyl-methacrylate (DMA) and a tetra-ethyleneglycol-dimethacrylate (TEGDMA) crosslinker. This hydrogel quickly and reversibly swells when placed environments of physiological buffer solutions (PBS) with ionic strengths ranging from 0.025 to 0.15 M. Chemical testing showed sensors with perforated diaphragms have higher sensitivity than those with solid diaphragms, and sensitivities ranging from 53.3+/-6.5 to 271.47+/-27.53 mV/V-M, depending on diaphragm size. Additionally, recent experiments show sensors utilizing Ultra Violet (UV) polymerized glucose sensitive hydrogels respond reversibly to physiologically relevant glucose concentrations from 0 to 20 mM.

Reinforcement of SBR/waste rubber powder vulcanizate with in situ generated zinc dimethacrylate

NASA Astrophysics Data System (ADS)

Wang, X. P.; Cheng, B. K.; Zhang, X.; Jia, D. M.

2016-07-01

Methyl acrylic acid/zinc oxide (MAA/ZnO) was introduced to modify styrene- butadiene rubber/waste rubber powder (SBR/WRP) composites by blending. The enhanced mechanical properties and processing ability were presumably originated from improved compatibility and interfacial interaction between WRP and the SBR matrix by the in situ polymerization of zinc dimethacrylate (ZDMA). A refined interface of the modified SBR/WRP composite was observed by scanning electron microscopy. The formation of ZDMA significantly increased the ionic bond content in the vulcanizate, resulting in exceptional mechanical performance. The comprehensive mechanical properties including tensile strength, tear strength and dynamic heat-building performance reached optimum values with 16 phr MAA.

Rechargeable calcium phosphate orthodontic cement with sustained ion release and re-release

NASA Astrophysics Data System (ADS)

Zhang, Ling; Weir, Michael D.; Chow, Laurence C.; Reynolds, Mark A.; Xu, Hockin H. K.

2016-11-01

White spot lesions (WSL) due to enamel demineralization are major complications for orthodontic treatments. Calcium phosphate (CaP) dental resins with Ca and P ion releases are promising for remineralization. However, previous Ca and P releases lasted for only weeks. Experimental orthodontic cements were developed using pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at mass ratio of 1:1 (PE); and PE plus 10% of 2-hydroxyethyl methacrylate (HEMA) and 5% of bisphenol A glycidyl dimethacrylate (BisGMA) (PEHB). Particles of amorphous calcium phosphate (ACP) were incorporated into PE and PEHB at 40% filler level. Specimens were tested for bracket-enamel shear bond strength, water sorption, CaP release, and ion recharge and re-release. PEHB+40ACP had higher bracket-enamel bond strength and ion release and rechargeability than PE+40ACP. ACP incorporation into the novel orthodontic cement did not adversely affect the bracket-enamel bond strength. Ion release and re-release from the novel ACP orthodontic cement indicated favorable release and re-release patterns. The recharged orthodontic cement could release CaP ions continuously for four weeks without further recharge. Novel rechargeable orthodontic cement containing ACP was developed with a high bracket-enamel bond strength and the ability to be repeatedly recharged to maintain long-term high levels of CaP ion releases.

Repair of dimethacrylate-based composite restorations by a silorane-based composite: a one-year randomized clinical trial.

PubMed

Popoff, D A V; Santa Rosa, T T A; Ferreira, R C; Magalhães, C S; Moreira, A N; Mjör, I A

2012-01-01

To investigate clinical performance of a low-shrinkage silorane-based composite resin when used for repairing conventional dimethacrylate-based composite restorations. Despite the continued development of resin-based materials, polymerization shrinkage and shrinkage stress still require improvement. A silorane-based monomer system was recently made available for dental restorations. This report refers to the use of this material for making repairs and evaluates the clinical performance of this alternative treatment. One operator repaired the defective dimethacrylate-based composite resin restorations that were randomly assigned to one of two treatment groups: control (n=50) repair with Adper SE Plus (3M/ESPE) and Filtek P60 Posterior Restorative (3M/ESPE), and test (n=50) repair with P90 System Adhesive Self-Etch Primer and Bond (3M/ESPE) and Filtek P90 Low Shrink Posterior Restorative (3M/ESPE). After one week, restorations were finished and polished. Two calibrated examiners (Kw≥0.78) evaluated all repaired restorations, blindly and independently, at baseline and one year. The parameters examined were marginal adaptation, anatomic form, surface roughness, marginal discoloration, postoperative sensitivity, and secondary caries. The restorations were classified as Alpha, Bravo, or Charlie, according to modified US Public Health Service criteria. Mann-Whitney and Wilcoxon tests were used to compare the groups. Of the 100 restorations repaired in this study, 93 were reexamined at baseline. Dropout from baseline to one-year recall was 11%. No statistically significant differences were found between the materials for all clinical criteria, at baseline or at one-year recall (p>0.05). No statistically significant differences were registered (p>0.05) for each material when compared for all clinical criteria at baseline and at one-year recall. The hypothesis tested in this randomized controlled clinical trial was accepted. After the one-year evaluations, the silorane-based composite exhibited a similar performance compared with dimethacrylate-based composite when used to make repairs.

Photopolymerization and Characterization of Dental Resin Cement Containing Nano Material.

PubMed

Kim, Duck Hyun; Sung, A-Young

2018-09-01

In this study, to manufacture dental resin cement, Bis-GMA was used as a major ingredient, TEGDMA was used as a diluent, and camphoroquinone was used as a photoinitiator. Nanodiamonds were added to increase the bonding strength. After mixing Bis-GMA, HPMA, TEGDMA, BHT, BPO, and camphoroquinone (photoinitiator), nanodiamonds were added at a ratio of 2-3%, and polymerization was done after stirring for 24 hours. Photopolymerization was also carried out with Dentmate (LWDEX WL-090) by irradiation at a 440-480 nm wavelength and at about 1000 mW/cm2 intensity for about 40 seconds. As a result of the SEM measurement for the surface analysis, the nanodiamonds were found to have been evenly distributed at 80∼100 nm sizes. The physical properties of each combination were also evaluated to analyze the functionality of the prepared resin cement and as a result, the cultured cells (L929) in all the combinations (Ref., ND-1, and ND-2) had no cytotoxicity. Also the mean shear bond strengths of the control group using commercial resin cement was the range of 5.87∼6.72 MPa. And also, the mean flexural strength was about 94 MPa. These results indicate that the resin cement that was manufactured in this study will have no clinical problem when commercialized for dental practice.

Influence of thermal expansion on shrinkage during photopolymerization of dental resins based on bis-GMA/TEGDMA.

PubMed

Mucci, Veronica; Arenas, Gustavo; Duchowicz, Ricardo; Cook, Wayne D; Vallo, Claudia

2009-01-01

The aim of this study was to assess volume changes that occur during photopolymerization of unfilled dental resins based on bis-GMA-TEGDMA. The resins were activated for visible light polymerization by the addition of camphorquinone (CQ) in combination with dimethylamino ethylmethacrylate (DMAEMA) or ethyl-4-dimethyl aminobenzoate (EDMAB). A fibre-optic sensing method based on a Fizeau-type interferometric scheme was employed for monitoring contraction during photopolymerization. Measurements were carried out on 10mm diameter specimens of different thicknesses (1 and 2mm). The high exothermic nature of the polymerization resulted in volume expansion during the heating, and this effect was more pronounced when the sample thickness increased. Two approaches to assess volume changes due to thermal effects are presented. Due to the difference in thermal expansion coefficients between the rubbery and glassy resins, the increase of volume due to thermal expansion was greater than the decrease in volume due to thermal contraction. As a result, the volume of the vitrified resins was greater than that calculated from polymerization contraction. The observed trends of shrinkage versus sample thickness are explained in terms of light attenuation across the path length during photopolymerization. Results obtained in this research highlight the inherent interlinking of non-isothermal photopolymerization and volumetric changes in bulk polymerizing systems.

Physical-chemical properties of dental composites and adhesives containing silane-modified SBA-15.

PubMed

Martim, Gedalias Custódio; Kupfer, Vicente Lira; Moisés, Murilo Pereira; Dos Santos, Andressa; Buzzetti, Paulo Henrique Maciel; Rinaldi, Andrelson Wellington; Rubira, Adley Forti; Girotto, Emerson Marcelo

2018-04-01

The aim of this study was to synthesize and characterize mesoporous materials SBA-15 and SBA-15 modified with 3-(methacryloxy)-propyl-trimethoxysilane (MPS) to be used as inorganic filler in restorative dental composites and adhesives, and evaluate the main physical-chemical properties of the resulting material. The SBA-15 and SBA-15/MPS were characterized by FTIR, BET and X-Ray and combined with TEGDMA, bis-GMA and commercial spherical silica to produce dental composites. Afterwards, the mesoporous materials were combined with TEGDMA, bis-GMA and HEMA to make adhesives. To compare the results, composites and adhesives containing only commercial spherical silica were investigated. Some physical-chemical properties such as degree of conversion (DC), flexural strength (FS) and modulus (FM), water sorption and solubility (W sp and W sl ), specific area (BET), and the leachable components were evaluated. The SBA-15/MPS can be used to prepare dental restorative materials, with some foreseeable advantages compared with pure SBA-15 dental materials and with improved properties compared with commercial spherical silica dental materials. An important improvement was that the dental materials based on modified SBA-15 presented a reduction of approximately 60% in leaching of unreacted monomers extracted by solvent compared to the control group. Copyright © 2018 Elsevier Ltd. All rights reserved.

Phthalates and bisphenols migration in Mexican food cans and plastic food containers.

PubMed

González-Castro, M I; Olea-Serrano, M F; Rivas-Velasco, A M; Medina-Rivero, E; Ordoñez-Acevedo, Leandro G; De León-Rodríguez, A

2011-06-01

The presence of endocrine disruptors bisphenol-A, bisphenol-A-dimethacrylate, bisphenol-A-diglycidyl-ether, phthalic-acid, dibutyl-phthalate, diethyl-phthalate and dioctyl-phthalate was determined in vegetable cans, baby bottles and microwaveable containers from the Mexican market. Gas-Chromatography-Mass-Spectrometry was used for the identification and High-Performance-Liquid-Chromatography with UV/Visible light and fluorescence detectors was used for the quantification. Endocrine disruptors were found in all samples. PA and DOP were the substances most commonly found, and maximum concentrations were 9.549 and 0.664 μg/kg, respectively from a jalapeno peppers can. Bisphenol A, phthalic-acid, bisphenol-A-dimethacrylate, bisphenol-A-diglycidyl-ether, dioctyl-phtalate and dibutyl-phthalate were found in baby bottles and microwaveable containers.

Rechargeable calcium phosphate orthodontic cement with sustained ion release and re-release

PubMed Central

Zhang, Ling; Weir, Michael D.; Chow, Laurence C.; Reynolds, Mark A.; Xu, Hockin H. K.

2016-01-01

White spot lesions (WSL) due to enamel demineralization are major complications for orthodontic treatments. Calcium phosphate (CaP) dental resins with Ca and P ion releases are promising for remineralization. However, previous Ca and P releases lasted for only weeks. Experimental orthodontic cements were developed using pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at mass ratio of 1:1 (PE); and PE plus 10% of 2-hydroxyethyl methacrylate (HEMA) and 5% of bisphenol A glycidyl dimethacrylate (BisGMA) (PEHB). Particles of amorphous calcium phosphate (ACP) were incorporated into PE and PEHB at 40% filler level. Specimens were tested for bracket-enamel shear bond strength, water sorption, CaP release, and ion recharge and re-release. PEHB+40ACP had higher bracket-enamel bond strength and ion release and rechargeability than PE+40ACP. ACP incorporation into the novel orthodontic cement did not adversely affect the bracket-enamel bond strength. Ion release and re-release from the novel ACP orthodontic cement indicated favorable release and re-release patterns. The recharged orthodontic cement could release CaP ions continuously for four weeks without further recharge. Novel rechargeable orthodontic cement containing ACP was developed with a high bracket-enamel bond strength and the ability to be repeatedly recharged to maintain long-term high levels of CaP ion releases. PMID:27808251

ILLUMINATING THE ROLE OF AGGLOMERATES ON CRITICAL PHYSICOCHEMICAL PROPERTIES OF AMORPHOUS CALCIUM PHOSPHATE COMPOSITES

PubMed Central

O’Donnell, J.N.R.; Antonucci, J.M.; Skrtic, D.

2009-01-01

Water sorption (WS), mechanical strength, and ion release of polymeric composites formulated with 40 % as-made or milled amorphous calcium phosphate (ACP) are compared after 1, 2 and 3 months of aqueous exposure. Ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate comprised the resin. The WS (mass %) peaked at 3 months. WS of as-made ACP composites was significantly higher than WS of milled ACP composites and copolymers. Both composite groups experienced decreases in biaxial flexural strength (BFS) with water aging, with milled ACP composites retaining a significantly higher BFS throughout immersion. Ion release was moderately reduced in milled ACP composites, though they remained superior to as-made ACP composites due to significantly lower WS and higher BFS after prolonged aqueous exposure. PMID:19774100

Final report of the safety assessment of methacrylate ester monomers used in nail enhancement products.

PubMed

2005-01-01

Methacrylate ester monomers are used in as artificial nail builders in nail enhancement products. They undergo rapid polymerization to form a hard material on the nail that is then shaped. While Ethyl Methacrylate is the primary monomer used in nail enhancement products, other methacrylate esters are also used. This safety assessment addresses 22 other methacrylate esters reported by industry to be present in small percentages as artificial nail builders in cosmetic products. They function to speed up polymerization and/or form cross-links. Only Tetrahydrofurfuryl Methacrylate was reported to the FDA to be in current use. The polymerization rates of these methacrylate esters are within the same range as Ethyl Methacrylate. While data are not available on all of these methacrylate esters, the available data demonstrated little acute oral, dermal, or i.p. toxicity. In a 28-day inhalation study on rats, Butyl Methacrylate caused upper airway irritation; the NOAEL was 1801 mg/m3. In a 28-day oral toxicity study on rats, t-Butyl Methacrylate had a NOAEL of 20 mg/kg/day. Beagle dogs dosed with 0.2 to 2.0 g/kg/day of C12 to C18 methacrylate monomers for 13 weeks exhibited effects only in the highest dose group: weight loss, emesis, diarrhea, mucoid feces, or salivation were observed. Butyl Methacrylate (0.1 M) and Isobutyl Methacrylate (0.1 M) are mildly irritating to the rabbit eye. HEMA is corrosive when instilled in the rabbit eye, while PEG-4 Dimethacrylate and Trimethylolpropane Trimethacrylate are minimally irritating to the eye. Dermal irritation caused by methacrylates is documented in guinea pigs and rabbits. In guinea pigs, HEMA, Isopropylidenediphenyl Bisglycidyl Methacrylate, Lauryl Methacrylate, and Trimethylolpropane Trimethacrylate are strong sensitizers; Butyl Methacrylate, Cyclohexyl Methacrylate, Hexyl Methacrylate, and Urethane Methacrylate are moderate sensitizers; Hydroxypropyl Methacrylate is a weak sensitizer; and PEG-4 Dimethacrylate and Triethylene Glycol Dimethacrylate are not sensitizers. Ethylene Glycol Dimethacrylate was not a sensitizer in one guinea pig study, but was a strong sensitizer in another. There is cross-reactivity between various methacrylate esters in some sensitization tests. Inhaled Butyl Methacrylate, HEMA, Hydroxypropyl Methacrylate, and Trimethylolpropane Trimethacrylate can be developmental toxicants at high exposure levels (1000 mg/kg/day). None of the methacrylate ester monomers that were tested were shown to have any endocrine disrupting activity. These methacrylate esters are mostly non-mutagenic in bacterial test systems, but weak mutagenic responses were seen in mammalian cell test systems. Chronic dermal exposure of mice to PEG-4 Dimethacrylate (25 mg, 2 x weekly for 80 weeks) or Trimethylolpropane Trimethacrylate (25 mg, 2 x weekly for 80 weeks) did not result in increased incidence of skin or visceral tumors. The carcinogenicity of Triethylene Glycol Dimethacrylate (5, 25, or 50%) was assessed in a mouse skin painting study (50 microl for 5 days/week for 78 weeks), but was not carcinogenic at any dose level tested. The Expert Panel was concerned about the strong sensitization and crossor co-reactivity potential of the methacrylate esters reviewed in this report. However, data demonstrated the rates of polymerization of these Methacrylates were similar to that of Ethyl Methacrylate and there would be little monomer available exposure to the skin. In consideration of the animal toxicity data, the CIR Expert Panel decided that these methacrylate esters should be restricted to the nail and must not be in contact with the skin. Accordingly, these methacrylate esters are safe as used in nail enhancement products when skin contact is avoided.

Fracture resistance of premolar teeth restored with silorane-based or dimethacrylate-based composite resins.

PubMed

Akbarian, Golsa; Ameri, Hamideh; Chasteen, Joseph E; Ghavamnasiri, Marjaneh

2014-01-01

To restore posterior teeth using low-shrinkage composite to minimize microleakage. To compare the fracture resistance of mesio-occlusal-distal (MOD) cavity preparations restored with either low-shrinkage composite or with dimethacrylate-based composite in conjunction with cavity liners and without them. The null hypothesis of the study is that there are no differences in either fracture resistance or fracture mode between the silorane group and dimethacrylate groups with and without the use of cavity liners. Sixty maxillary premolars were divided into six groups of 10. MOD cavities were prepared in four groups: F: posterior composite (Filtek P60); GF: 0.5-mm Glass Ionomer (Fuji LC) + posterior composite; FF: 0.5-mm flowable composite (Filtek Supreme XT) + posterior composite; and S: low-shrinkage composite (Filtek P90). Negative (N) and positive (P) control groups consisted of unrestored and sound teeth, respectively. The specimens were thermocycled and loaded. Data were analyzed using analysis of variance, Tukey, and chi-square tests (α = 0.05). Groups FF (1643.09 ± 187/80 N) and GF (1596.80 ± 163/93 N) (p = 0.06 > 0.05) were statistically identical, although less than group P (1742/33 ± 110/08 N), but still demonstrated greater fracture resistance than the other groups. The fracture resistance of group S (1434/69 ± 107/62 N) was identical to GF and FF (p = 0.06 > 0.05). The fracture resistance of F (1353/19 ± 233/90 N) was less than GF and FF, and statistically identical to S (p = 0.87 > 0.05). Silorane-based composite showed a resistance to fracture similar to methacrylate-based composite restorations regardless of whether cavity liners were used. The findings of this study support the selection of silorane-based composite for the restoration of maxillary premolars with standardized Class II cavity preparations in order to strengthen the resistance to fracture to the same extent as do dimethacrylate composites using cavity liners or without them. © 2013 Wiley Periodicals, Inc.

The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

NASA Astrophysics Data System (ADS)

Yepez, Johanna

Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=<0.001) as well as for the pairwise comparison between the different filler group values and between the different soaking times as an individual treatment. Overall, longer soaking times resulted in lower mean DTS values. The DTS of the PCNC for filler #1 decreased to 82.4% of the original value after 1 day of soaking, 67.2% after 7 days and 27.2 % after 28 days. For filler #2 decreased to 54.8% of the original value after 1 day of soaking, 62.3% after 7 days and 61.2% after 28 days. For filler #3 decreased to 71.2% of the original value, 67.3% after 7 days and 51.4% after 28 days (Fig 8). Conclusions: Within the limitation of this study it can be concluded that the use of coupling agent will significantly influence the degradation of the material under wet environment. Clinical Implication: Changes within matrix composition and bonding interphase of resin base composites promise improvements of mechanical properties, decreasing the incidence of clinical failure of posterior composite restorations, hence resulting in a more ideal restorative material for use in posterior segment. The results of this investigation showed that the deficiency of hydrostability in dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging.

PubMed

Furuse, Adilson Y; Gordon, Kathryn; Rodrigues, Flávia P; Silikas, Nick; Watts, David C

2008-11-01

To evaluate the colour-stability and gloss-retention of silorane versus dimethacrylate composites exposed to accelerated aging from daylight radiation. Five disc-shaped specimens of photo-cured resin-composites were prepared and manually polished for each material (Filtek Silorane, Herculite XRV, Tetric Evoceram and QuiXfil). Colour and gloss were evaluated before and after periods (baseline, 24, 72, 120 and 192 h) of accelerated photo-aging in xenon light following ISO 7491:2000. Colour measurements were performed with a colourimeter according to the CIE-Lab colour-space. The colour change (DeltaE) for each time was calculated. The surface gloss was measured using a glossmeter. Results were evaluated using one-way ANOVA and Tukey tests (alpha=0.05). Correlations between logtime, DeltaE and gloss were evaluated using Pearson's correlation (alpha=0.05). Materials generally decreased in L and a and increased in b. The strong exception was Filtek Silorane which maintained a and b. DeltaE was found to be a positive linear function of logtime for all materials. Materials varied in the magnitude and rate of increase of DeltaE with logtime: QuiXfil>Tetric EvoCeram>(Filtek Silorane>or=Herculite XRV). DeltaE remained<3.3 for Filtek Silorane and Herculite XRV. Gloss was found to be a negative linear function of logtime. Gloss was maximal in the sequence: Filtek Silorane approximately Tetric EvoCeram>Herculite XRV>QuiXfil. Silorane gave the best overall performance in stability over time, compared to a set of representative dimethacrylate composites.

Biological and physicochemical properties of carbon-graphite fibre-reinforced polymers intended for implant suprastructures.

PubMed

Segerström, Susanna; Sandborgh-Englund, Gunilla; Ruyter, Eystein I

2011-06-01

The aim of this study was to determine water sorption, water solubility, dimensional change caused by water storage, residual monomers, and possible cytotoxic effects of heat-polymerized carbon-graphite fibre-reinforced composites with different fibre loadings based on methyl methacrylate/poly(methyl methacrylate) (MMA/PMMA) and the copolymer poly (vinyl chloride-co-vinyl acetate). Two different resin systems were used. Resin A contained ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (1,4-BDMA); the cross-linker in Resin B was diethylene glycol dimethacrylate (DEGDMA). The resin mixtures were reinforced with 24, 36 and 47 wt% surface-treated carbon-graphite fibres. In addition, polymer B was reinforced with 58 wt% fibres. Water sorption was equal to or below 3.34±1.18 wt%, except for the 58 wt% fibre loading of polymer B (5.27±1.22 wt%). Water solubility was below 0.36±0.015 wt%, except for polymer B with 47 and 58 wt% fibres. For all composites, the volumetric increase was below 0.01±0.005 vol%. Residual MMA monomer was equal to or below 0.68±0.05 wt% for the fibre composites. The filter diffusion test and the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay demonstrated no cytotoxicity for the carbon-graphite fibre-reinforced composites, and residual cross-linking agents and vinyl chloride were not detectable by high-performance liquid chromatography (HPLC) analysis. © 2011 Eur J Oral Sci.

The sensitizing capacity of multifunctional acrylates in the guinea pig.

PubMed

Björkner, B

1984-10-01

The multifunctional acrylates used in ultraviolet (UV) curable resins act as cross-linkers and "diluents". They are usually based on di(meth)acrylate esters of dialcohols or tri- and tetra-acrylate esters of polyalcohols. In UV-curable coatings, the most commonly used are pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA) and 1,6-hexanediol diacrylate (HDDA). In other uses, such as dental composite resin materials, the dimethacrylic monomers based on n-ethylene glycol are the most useful. The sensitizing capacity of various multifunctional acrylates and their cross-reactivity pattern have been investigated with the guinea pig maximization test. The tests show that BUDA (1,4-butanediol diacrylate) and HDDA are moderate to strong sensitizers and that they probably cross-react with each other. The n-ethylene glycol diacrylates and methacrylates tested are weak or non-sensitizers. Tripropylene glycol diacrylate (TPGDA) is a moderate and neopentyl glycol diacrylate (NPGDA) a strong sensitizer, whereas neopentyl glycol dimethacrylate is a non-sensitizer. The commercial PETA is a mixture of pentaerythritol tri- and tetra-acrylate (PETA-3 and PETA-4). PETA-3 is a much stronger sensitizer than PETA-4. Simultaneous reactions were seen between PETA-3, PETA-4 and TMPTA. The oligotriacrylate OTA 480 is a moderate sensitizer, but no concomitant reactions were seen with PETA-3, PETA-4 or TMPTA. Of the multifunctional acrylates tested, the di- and triacrylic compounds should be regarded as potent sensitizers. The methacrylated multifunctional acrylic compounds are weak or non-sensitizers.

Effect of silane coupling agents on the chemical and physical properties of photocrosslinked poly(dimethylsiloxane) dimethacrylate/poly(ethylene glycol) diacrylate hydrogel

NASA Astrophysics Data System (ADS)

Lim, K. W.; Hamid, Z. A. A.

2017-07-01

Inorganic-organic hydrogels based on dimethacrylated polydimethylsiloxane (PDMSMA) and diacrylated poly(ethylene glycol) (PEGDA) macromers were prepared via photocrosslinking method. Silane coupling agent was incorporated into the hydrogel formulations to overcome the phase incompatibility. Pure PEGDA (0:100) hydrogels showed the highest value of ESR %, while pure PDMSMA (100:0) hydrogels showed no swelling as we expected. Inclusion of more hydrophobic domains resulted in a lower value of ESR %, i.e. in 75:25 hybrid hydrogels. Beside, we had noticed 50:50 and 75:25 hybrid hydrogels disintegrate during swelling period. However, their integrity was improved and sustained after the coupling agent was added. Similarly, the value of E* for the hybrid hydrogels showed an increment after the coupling agent was incorporated, and this is in a good agreement with the SEM micrograph which display an improved interfacial adhesion.

Light-Curing Volumetric Shrinkage in Dimethacrylate-Based Dental Composites by Nanoindentation and PAL Study.

PubMed

Shpotyuk, Olha; Adamiak, Stanislaw; Bezvushko, Elvira; Cebulski, Jozef; Iskiv, Maryana; Shpotyuk, Oleh; Balitska, Valentina

2017-12-01

Light-curing volumetric shrinkage in dimethacrylate-based dental resin composites Dipol® is examined through comprehensive kinetics research employing nanoindentation measurements and nanoscale atomic-deficient study with lifetime spectroscopy of annihilating positrons. Photopolymerization kinetics determined through nanoindentation testing is shown to be described via single-exponential relaxation function with character time constants reaching respectively 15.0 and 18.7 s for nanohardness and elastic modulus. Atomic-deficient characteristics of composites are extracted from positron lifetime spectra parameterized employing unconstrained x3-term fitting. The tested photopolymerization kinetics can be adequately reflected in time-dependent changes observed in average positron lifetime (with 17.9 s time constant) and fractional free volume of positronium traps (with 18.6 s time constant). This correlation proves that fragmentation of free-volume positronium-trapping sites accompanied by partial positronium-to-positron traps conversion determines the light-curing volumetric shrinkage in the studied composites.

Thermorheological characteristics and comparison of shape memory polymers fabricated by novel 3D printing technique

NASA Astrophysics Data System (ADS)

Hassan, Rizwan Ul; Jo, Soohwan; Seok, Jongwon

The feasibility of fabrication of shape memory polymers (SMPs) was investigated using a customized 3-dimensional (3D) printing technique with an excellent resolution that could be less than 100 microns. The thermorheological effects of SMPs were adjusted by contact and non-contact triggering, which led to the respective excellent shape recoveries of 100% and 99.89%. Thermogravimetric analyses of SMPs resulted in a minor weight loss, thereby revealing good thermal stability at higher temperatures. The viscoelastic properties of SMPs were measured using dynamic mechanical analyses, exhibiting increased viscous and elastic characteristics. Mechanical strength, thermal stability and viscoelastic properties, of the two SMPs were compared [di(ethylene) glycol dimethacrylate (DEGDMA) and poly (ethylene glycol) dimethacrylate (PEGDMA)] to investigate the shape memory behavior. This novel 3D printing technique can be used as a promising method for fabricating smart materials with increased accuracy in a cost-effective manner.

Mechanical properties of provisional dental materials: A systematic review and meta-analysis

PubMed Central

Bellot-Arcís, Carlos; Pascual-Moscardó, Agustín; Almerich-Silla, José Manuel

2018-01-01

Provisional restorations represent an important phase during the rehabilitation process, knowledge of the mechanical properties of the available materials allows us to predict their clinical performance. At present, there is no systematic review, which supports the clinicians’ criteria, in the selection of a specific material over another for a particular clinical situation. The purpose of this systematic review and meta-analysis was to assess and compare the mechanical properties of dimethacrylates and monomethacrylates used in fabricating direct provisional restorations, in terms of flexural strength, fracture toughness and hardness. This review followed the PRISMA guidelines. The searches were conducted in PubMed, Embase, Web of Science, Scopus, the New York Academy of Medicine Grey Literature Report and were complemented by hand-searching, with no limitation of time or language up to January 10, 2017. Studies that assess and compare the mechanical properties of dimethacrylate- and monomethacrylate-based provisional restoration materials were selected. A quality assessment of full-text articles were performed according to modified ARRIVE and CONSORT criteria and modified Cochrane Collaboration’s tool for in vitro studies. Initially, 256 articles were identified. After removing the duplicates and applying the selection criteria, 24 articles were included in the qualitative synthesis and 7 were included in the quantitative synthesis (meta-analysis). It may be concluded that dimethacrylate-based provisional restorations presented better mechanical behavior than monomethacrylate-based ones in terms of flexural strength and hardness. Fracture toughness showed no significant differences. Within the monomethacrylate group, polymethylmethacrylate showed greater flexural strength than polyethylmethacrylate. PMID:29489883

Progress in dimethacrylate-based dental composite technology and curing efficiency.

PubMed

Leprince, Julian G; Palin, William M; Hadis, Mohammed A; Devaux, Jacques; Leloup, Gaetane

2013-02-01

This work aims to review the key factors affecting the polymerization efficiency of light-activated resin-based composites. The different properties and methods used to evaluate polymerization efficiency will also be critically appraised with focus on the developments in dental photopolymer technology and how recent advances have attempted to improve the shortcomings of contemporary resin composites. Apart from the classical literature on the subject, the review focused in particular on papers published since 2009. The literature research was performed in Scopus with the terms "dental resin OR dimethacrylate". The list was screened and all papers relevant to the objectives of this work were included. Though new monomer technologies have been developed and some of them already introduced to the dental market, dimethacrylate-based composites still currently represent the vast majority of commercially available materials for direct restoration. The photopolymerization of resin-based composites has been the subject of numerous publications, which have highlighted the major impact of the setting process on material properties and quality of the final restoration. Many factors affect the polymerization efficiency, be they intrinsic; photoinitiator type and concentration, viscosity (co-monomer composition and ratio, filler content) and optical properties, or extrinsic; light type and spectrum, irradiation parameters (radiant energy, time and irradiance), curing modes, temperature and light guide tip positioning. : This review further highlights the apparent need for a more informative approach by manufacturers to relay appropriate information in order for dentists to optimize material properties of resin composites used in daily practice. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Bisphenol A Release: Survey of the Composition of Dental Composite Resins

PubMed Central

Dursun, Elisabeth; Fron-Chabouis, Hélène; Attal, Jean-Pierre; Raskin, Anne

2016-01-01

Background: Bisphenol A (BPA) is an endocrine disruptor with potential toxicity. Composite resins may not contain pure BPA, but its derivatives are widely used. Several studies found doses of BPA or its derivatives in saliva or urine of patients after composite resin placement. Objective: The aims of this study were to establish an exhaustive list of composite resins marketed in Europe and their composition, and to assess the extent of BPA derivatives used. Methods: A research on manufacturers' websites was performed to reference all composite resins marketed in Europe, then their composition was determined from both material safety data sheets and a standardized questionnaire sent to manufacturers. Manufacturers had to indicate whether their product contained the monomers listed, add other monomers if necessary, or indicate “not disclosed”. Results: 160 composite resins were identified from 31 manufacturers and 23 manufacturers (74.2%) responded to the survey. From the survey and websites, the composition of 130 composite resins (81.2%) was: 112 (86.2%) based on BPA derivatives, 97 (74.7%) on bis-GMA, 17 (13.1%) without monomer derived from BPA (UDMA, sometimes with TEGDMA) and 6 (4.6%) with UDMA (only); 1 (0.8%) did not contain a BPA derivative or UDMA or TEGDMA. Pure BPA was never reported. Conclusion: This work has established a list of 18 composite resins that contain no BPA derivative. Manufacturers should be required to report the exact composition of their products as it often remains unclear or incomplete. PMID:27708726

Bisphenol A Release: Survey of the Composition of Dental Composite Resins.

PubMed

Dursun, Elisabeth; Fron-Chabouis, Hélène; Attal, Jean-Pierre; Raskin, Anne

2016-01-01

Bisphenol A (BPA) is an endocrine disruptor with potential toxicity. Composite resins may not contain pure BPA, but its derivatives are widely used. Several studies found doses of BPA or its derivatives in saliva or urine of patients after composite resin placement. The aims of this study were to establish an exhaustive list of composite resins marketed in Europe and their composition, and to assess the extent of BPA derivatives used. A research on manufacturers' websites was performed to reference all composite resins marketed in Europe, then their composition was determined from both material safety data sheets and a standardized questionnaire sent to manufacturers. Manufacturers had to indicate whether their product contained the monomers listed, add other monomers if necessary, or indicate "not disclosed". 160 composite resins were identified from 31 manufacturers and 23 manufacturers (74.2%) responded to the survey. From the survey and websites, the composition of 130 composite resins (81.2%) was: 112 (86.2%) based on BPA derivatives, 97 (74.7%) on bis-GMA, 17 (13.1%) without monomer derived from BPA (UDMA, sometimes with TEGDMA) and 6 (4.6%) with UDMA (only); 1 (0.8%) did not contain a BPA derivative or UDMA or TEGDMA. Pure BPA was never reported. This work has established a list of 18 composite resins that contain no BPA derivative. Manufacturers should be required to report the exact composition of their products as it often remains unclear or incomplete.

Cytotoxicity of silica-glass fiber reinforced composites.

PubMed

Meriç, Gökçe; Dahl, Jon E; Ruyter, I Eystein

2008-09-01

Silica-glass fiber reinforced polymers can be used for many kinds of dental applications. The fiber reinforcement enhances the mechanical properties of the polymers, and they have good esthetic attributes. There is good initial bonding of glass fibers to polymers via an interface made from silane coupling agents. The aim of this in vitro study was to determine the cytotoxicity of two polymers reinforced with two differently sized silica-glass fibers before and after thermal cycling. Cytotoxicity of the polymers without fibers was also evaluated. Two different resin mixtures (A and B) were prepared from poly(vinyl chloridecovinylacetate) powder and poly(methyl methacrylate) (PMMA) dissolved in methyl methacrylate and mixed with different cross-linking agents. The resin A contained the cross-linking agents ethylene glycol dimethacrylate and 1,4-butanediol dimethacrylate, and for resin B diethylene glycol dimethacrylate was used. Woven silica-glass fibers were used for reinforcement. The fibers were sized with either linear poly(butyl methacrylate)-sizing or cross-linking PMMA-sizing. Cytotoxicity was evaluated by filter diffusion test (ISO 7405:1997) of newly made and thermocycled test specimens. Extracts were prepared according to ISO 10993-12 from newly made and from thermocycled specimens and tested by the MTT assay. The results from the experiments were statistically analyzed by one-way ANOVA and Tukey's test (rho<0.05). The filter diffusion test disclosed no change in staining intensity at the cell-test sample contact area indicating non-cytotoxicity in all experimental groups. Cell viability assessed by MTT assay was more than 90% in all experimental groups. All are non-cytotoxic. It can be concluded that correctly processed heat polymerized silica-glass fiber reinforced polymers induced no cytotoxicity and that thermocycling did not alter this property.

Preparation of poly(trimethyl-2-methacroyloxyethylammonium chloride-co-ethylene glycol dimethacrylate) monolith and its application in solid phase microextraction of brominated flame retardants.

PubMed

Yang, Ting-ting; Zhou, Lin-feng; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin; Chen, Hong-yuan

2013-05-24

A capillary poly(trimethyl-2-methacroyloxyethylammonium chloride-co-ethylene glycol dimethacrylate) monolith was in situ synthesized by thermally initiated free radical co-polymerization using trimethyl-2-methacroyloxyethylammonium chloride (MATE) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. N,N-dimethylformamide and polyethylene glycol 6000 were used as solvent and porogen, respectively. The morphology and porous structure of the resulting monoliths were assessed by scanning electron microscope. In order to prepare practically useful poly(MATE-co-EGDMA) monoliths with low flow resistance and good mechanical strength, some parameters such as PEG-6000 to DMF ratio, total monomer to porogen ratio, and crosslinker to monomer ratio were optimized systematically. Moreover, the extraction mechanism was evaluated using two series of compounds, alkylbenzenes and weak acids, as model compounds on poly(MATE-co-EGDMA) monoliths as liquid chromatographic stationary phase. Finally, the monoliths were applied as the solid phase microextraction medium, and a simple off-line method for simultaneous determination of three brominated flame retardants, 2,4,6-tribromophenol (TBP), tetrabromobisphenol A (TBBPA) and 4,4'-dibrominated diphenyl ether (DBDPE), in environmental waters was developed by coupling the polymer monolith microextraction to HPLC with UV detection. The regression equations for these three brominated flame retardants showed good linearity from their limit of quantification to 5000ng/mL. The limits of detection were 0.20, 0.15 and 0.10ng/mL for TBP, TBBPA and DBDPE, respectively. The recovery of the proposed method was 78.7-106.1% with intra-day relative standard deviation of 1.3-4.4%. Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication and characterization of shape memory polymers at small-scales

NASA Astrophysics Data System (ADS)

Wornyo, Edem

The objective of this research is to thoroughly investigate the shape memory effect in polymers, characterize, and optimize these polymers for applications in information storage systems. Previous research effort in this field concentrated on shape memory metals for biomedical applications such as stents. Minimal work has been done on shape memory polymers; and the available work on shape memory polymers has not characterized the behaviors of this category of polymers fully. Copolymer shape memory materials based on diethylene glycol dimethacrylate (DEGDMA) crosslinker, and tert butyl acrylate (tBA) monomer are designed. The design encompasses a careful control of the backbone chemistry of the materials. Characterization methods such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC); and novel nanoscale techniques such as atomic force microscopy (AFM), and nanoindentation are applied to this system of materials. Designed experiments are conducted on the materials to optimize spin coating conditions for thin films. Furthermore, the recovery, a key for the use of these polymeric materials for information storage, is examined in detail with respect to temperature. In sum, the overarching objectives of the proposed research are to: (i) Design shape memory polymers based on polyethylene glycol dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) crosslinkers, 2-hydroxyethyl methacrylate (HEMA) and tert-butyl acrylate monomer (tBA). (ii) Utilize dynamic mechanical analysis (DMA) to comprehend the thermomechanical properties of shape memory polymers based on DEGDMA and tBA. (iii) Utilize nanoindentation and atomic force microscopy (AFM) to understand the nanoscale behavior of these SMPs, and explore the strain storage and recovery of the polymers from a deformed state. (iv) Study spin coating conditions on thin film quality with designed experiments. (iv) Apply neural networks and genetic algorithms to optimize these systems.

Live RB51 vaccine lyophilized hydrogel formulations with increased shelf life for practical ballistic delivery

USDA-ARS?s Scientific Manuscript database

Ballistic delivery capability is essential to delivering vaccines and other therapeutics effectively to both livestock and wildlife in many global scenarios. Here, lyophilized poly(ethylene glycol) (PEG)-glycolide dimethacrylate crosslinked but degradable hydrogels were assessed as payload vehicles ...

Determination of steroid sex hormones in wastewater by stir bar sorptive extraction based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material and liquid chromatographic analysis.

PubMed

Huang, Xiaojia; Lin, Jianbin; Yuan, Dongxing; Hu, Rongzong

2009-04-17

In this study, a simple and rapid method was developed for the determination of seven steroid hormones in wastewater. Sample preparation and analysis were performed by stir bar sorptive extraction (SBSE) based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material (SBSEM) combined with high-performance liquid chromatography with diode array detection. To achieve the optimum extraction performance, several main parameters, including extraction and desorption time, pH value and contents of inorganic salt in the sample matrix, were investigated. Under the optimized experimental conditions, the method showed good linearity and repeatability, as well as advantages such as sensitivity, simplicity, low cost and high feasibility. The extraction performance of SBSEM to the target compounds also compared with commercial SBSE which used polydimethylsiloxane as coating. Finally, the proposed method was successfully applied to the determination of the target compounds in wastewater samples. The recoveries of spiked target compounds in real samples ranged from 48.2% to 110%.

Immobilization of yeast cells with ionic hydrogel carriers by adhesion-multiplication.

PubMed

Zhaoxin, L; Fujimura, T

2000-12-01

The mixture of an ionic monomer, 2-acrylamido 2-methylpropanesulfonic acid (TBAS), and a series of poly(ethylene glycol) dimethacrylate (nG) monomers were copolymerized with 60Co gamma-rays, and the produced ionic hydrogel polymers were used for immobilization of yeast cells. The cells were adhered onto the surface of the hydrogel polymers and intruded into the interior of the polymers with growing. The immobilized yeast cells with these hydrogel polymers had higher ethanol productivity than that of free cells. The yield of ethanol with poly(TBAS-14G) carrier was the highest and increased by 3.5 times compared to the free cells. It was found that the ethanol yield increased with the increase of glycol number in poly(ethylene glycol) dimethacrylate. The state of the immobilized cells was observed with microscope, and it was also found that the difference in the ethanol productivity is mainly due to the difference in the internal structure and properties of polymer carrier, such as surface charge, hydrophilicity, and swelling ability of polymer carrier.

Removal of fumonisin B1 and B2 from model solutions and red wine using polymeric substances.

PubMed

Carrasco-Sánchez, Verónica; Kreitman, Gal Y; Folch-Cano, Christian; Elias, Ryan J; Laurie, V Felipe

2017-06-01

Fumonisins are a group of mycotoxins found in various foods whose consumption is known to be harmful for human health. In this study, we evaluated the ability of three polymers (Polyvinylpolypyrrolidone, PVPP; a resin of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate, PVP-DEGMA-TAIC; and poly(acrylamide-co-ethylene glycol-dimethacrylate), PA-EGDMA) to remove fumonisin B 1 (FB1) and fumonisin B 2 (FB2) from model solutions and red wine. Various polymer concentrations (1, 5 and 10mgmL -1 ) and contact times (2, 8 and 24h) were tested, with all polymers exhibiting fumonisin removal capacities (monitored by LC-MS). The impact of all polymers on polyphenol removal was also assessed. PA-EGDMA showed to be the most promising polymer, removing 71% and 95% of FB 1 , and FB 2 , respectively, with only a 22.2% reduction in total phenolics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ensuring repeatability and robustness of poly(glycidyl methacrylate-co-ethylene dimethacrylate) HPLC monolithic columns of 3 mm id through covalent bonding to the column wall.

PubMed

Laaniste, Asko; Kruve, Anneli; Leito, Ivo

2013-08-01

Two different methods to reinforce the poly(glycidyl methacrylate-co-ethylene dimethacrylate) HPLC monolithic columns of 3 mm id in a glass column reservoir were studied: composite columns with polymeric particles in the monolith and surface treatment of the reservoir wall. Of the two methods used to counter the mechanical instability and formation of flow channels (composite columns and column wall surface treatment), we demonstrated that proper column wall surface treatment was sufficient to solve both problems. Our study also indicated that no surface treatment is efficient, and of the methods studied silanization in acidified ethanol solution and constant renewal of the reaction mixture (dynamic mode) proved to be the most effective. As a result of this study, we have been able to prepare repeatable and durable methacrylate HPLC columns with good efficiencies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Laser-assisted and Conventional In-office Bleaching on Monomer Release from Microhybrid and Nanohybrid Composite.

PubMed

Omrani, Ladan Ranjbar; Farjadfar, Shayan; Pedram, Parham; Sadray, Sima; Kamangar, Sedighe Sadat Hashemi; Chiniforoush, Nasim

2017-06-30

Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P < 0.05). For UDMA the interaction was significant only after 1 week. In microhybrid composites, the CO subgroup showed more monomer release than LBH and LBO. In nanohybrid composites, LBH showed more monomer release than CIB and CO subgroups. For BIS-GMA monomers the interaction was significant at all time periods and the LBH subgroup of nanohybrid composite had significantly more BIS_GMA release in comparison to other subgroups. Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.

Elution of monomer from different bulk fill dental composite resins.

PubMed

Cebe, Mehmet Ata; Cebe, Fatma; Cengiz, Mehmet Fatih; Cetin, Ali Rıza; Arpag, Osman Fatih; Ozturk, Bora

2015-07-01

The purpose of this study was to evaluate the elution of Bis-GMA, TEGDMA, HEMA, and Bis-EMA monomers from six bulk fill composite resins over four different time periods, using HPLC. Six different composite resin materials were used in the present study: Tetric Evo Ceram Bulk Fill (Ivoclar Vivadent, Amherst, NY), X-tra Fill (VOCO, Cuxhaven, Germany), Sonic Fill (Kerr, Orange, CA, USA), Filtek Bulk Fill (3M ESPE Dental Product, St. Paul, MN), SDR (Dentsply, Konstanz, Germany), EQUIA (GC America INC, Alsip, IL). The samples (4mm thickness, 5mm diameter) were prepared and polymerized for 20s with a light emitted diode unit. After fabrication, each sample was immediately immersed in 75wt% ethanol/water solution used as extraction fluid and stored in the amber colored bottles at room temperature. Ethanol/water samples were taken (0.5mL) at predefined time intervals:10m (T1), 1h (T2), 24h (T3) and 30 days (T4). These samples were analyzed by HPLC. The obtained data were analyzed with one-way ANOVA and Tukey HSD at significance level of p<0.05. Amount of eluted Bis-EMA and Bis-GMA from Tetric Evo Ceram Bulk Fill and amount of eluted TEGDMA and HEMA from X-tra Fill higher than others composites (p<0.05). Residual monomers were eluted from bulk fill composite resins in all time periods and the amount of eluted monomers was increased with time. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The reciprocity law concerning light dose relationships applied to BisGMA/TEGDMA photopolymers: theoretical analysis and experimental characterization.

PubMed

Wydra, James W; Cramer, Neil B; Stansbury, Jeffrey W; Bowman, Christopher N

2014-06-01

A model BisGMA/TEGDMA unfilled resin was utilized to investigate the effect of varied irradiation intensity on the photopolymerization kinetics and shrinkage stress evolution, as a means for evaluation of the reciprocity relationship. Functional group conversion was determined by FTIR spectroscopy and polymerization shrinkage stress was obtained by a tensometer. Samples were polymerized with UV light from an EXFO Acticure with 0.1wt% photoinitiator. A one-dimensional kinetic model was utilized to predict the conversion-dose relationship. As irradiation intensity increased, conversion decreased at a constant irradiation dose and the overall dose required to achieve full conversion increased. Methacrylate conversion ranged from 64±2% at 3mW/cm(2) to 78±1% at 24mW/cm(2) while the final shrinkage stress varied from 2.4±0.1MPa to 3.0±0.1MPa. The ultimate conversion and shrinkage stress levels achieved were dependent not only upon dose but also the irradiation intensity, in contrast to an idealized reciprocity relationship. A kinetic model was utilized to analyze this behavior and provide theoretical conversion profiles versus irradiation time and dose. Analysis of the experimental and modeling results demonstrated that the polymerization kinetics do not and should not be expected to follow the reciprocity law behavior. As irradiation intensity is increased, the overall dose required to achieve full conversion also increased. Further, the ultimate conversion and shrinkage stress that are achieved are not dependent only upon dose but rather upon the irradiation intensity and corresponding polymerization rate. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation

PubMed Central

Brambilla, Eugenio; Ionescu, Andrei; Mazzoni, Annalisa; Cadenaro, Milena; Gagliani, Massimo; Ferraroni, Monica; Tay, Franklin; Pashley, David; Breschi, Lorenzo

2014-01-01

Objectives To evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation. Methods Five light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch- and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24 h-incubation at 37 °C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Results R2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results. Conclusions The null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors. PMID:24954666

Influence of ionizing radiation on the mechanical properties of BisGMA/TEGDMA based experimental resin

NASA Astrophysics Data System (ADS)

LMP, Campos; Boaro, LC; LKG, Santos; Parra, DF; Lugão, AB

2015-10-01

Dental restorative composites are activated by visible light and the polymerization process, known as direct technique, is initiated by absorbing light in a specific wavelength range (450-500 nm). However this technique presented some disadvantages. If light is not inserted correctly, layers uncured can cause countless damage to restoration, especially with regard to mechanical properties. A clinical alternative used to reduce the shortcomings of direct application is the use of composite resins for indirect application. These composites are adaptations of resins prepared for direct use, with differences mainly in the healing process. Besides the traditional photoactivation, indirect application composites may be submitted to particular curing conditions, such as a slow curing rate, heating, vacuum, and inert-gas pressure leading to an oxygen-free environment. However few studies have been conducted on the process of post-curing by ionizing radiation at low doses. On this sense the purpose of this study was to evaluate possible interactions of ionizing radiation in the post-curing process of the experimental composites based on BisGMA/TEGDMA filled with silica Aerosil OX-50 silanized. Characterization of the experimental composites was performed by thermogravimetry analysis, infrared spectroscopy, elastic modulus and flexural strength. Statistical analysis of results was calculated by one-way ANOVA/Tukey's test. Cross-linking of the polymeric matrix caused by ionizing radiation, influenced the thermal stability of irradiated specimens. FTIR analysis showed that the ionizing radiation induced a post-cure reaction in the specimens. The irradiation dose influenced directly the mechanical properties that showed a strong positive correlation between flexural strength and irradiation and between modulus strength and irradiation.

40 CFR 721.10101 - Copolymer of alkyl acrylate and ethyleneglycol dimethacrylate (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... workplace. Requirements as specified in § 721.63 (a)(4), (a)(5), (a)(6)(i), (a)(6)(ii), (b), and (c). The following National Institute for Occupational Safety and Health (NIOSH)-approved respirators with an... PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES...

Morphology study of peroxide-induced dynamically vulcanized polypropylene/ethylene-propylene-diene monomer/zinc dimethacrylate blends during tensile deformation.

PubMed

Chen, Yukun; Xu, Chuanhui; Cao, Liming; Wang, Yanpeng; Fang, Liming

2013-06-27

Polypropylene (PP)/ethylene-propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blend (EPDM/PP ratio of 30/70) with remarkable extensibility was successfully prepared via peroxide dynamic vulcanization. The uniaxial tensile properties, crystallization behavior, structure, and morphology during stretching were investigated. The tensile process study showed that the PP/EPDM/ZDMA blend exhibited the rubbery-like behavior with an elongation beyond 600%. The ZDMA graft-product domain increased the compatibility and interfacial adhesion between rubber and PP phases, while it reduced the crystallinity of the PP phase. On the basis of TEM and SEM analyses, we found that the cross-linked rubber particles could be elongated and oriented along the tensile direction, whereas the ZDMA graft-product domain "encapsulated" rubber phase together, acting as a "bridge" between elongated rubber phases and the PP phase during uniaxial stretching. The stress could be effectively transferred from the PP phase to the numerous elongated rubber phases due to the excellent compatibility and interfacial adhesion between rubber and PP phases, resulting in the rubbery-like behavior.

Simultaneous Measurement of Fluorescence, Conversion and Physical/mechanical Properties for Monitoring Bulk and Localized Photopolymerization Reactions in Heterogeneous Systems

PubMed Central

Medel, S.; Bosch, P.; Grabchev, I.; Shah, P. K.; Liu, J.; Aguirre-Soto, A.; Stansbury, J. W.

2016-01-01

An FT-NIR spectrometer, rheometer and fluorescence spectrophotometer were coupled for the real-time monitoring of polymerization reactions, allowing the simultaneous tracking of polymerization kinetics, storage modulus as well as fluorescence. In this study, a methacrylate functionalized dansyl chromophore (DANSMA) was synthesized and two different nanogels were made from urethane dimethacrylate and isobornyl methacrylate. Two series of resin formulations were prepared using the DANSMA probe, ethoxylated bisphenol A dimethacrylate as the matrix monomer, Irgacure® 651 as the initiator and the dispersed, monomer-swollen nanogels to give clear UV-curable resins. Placement of the fluorescent probe either throughout the resin or linked into the nanogel before its dispersion in the matrix provides a tool to study how the nanogel structure affects local network development by means of fluorescence from the DANSMA probe. We demonstrate the potential of this new technique using a composite as the two phase system (resin and polymerizable nanogel) including a dansyl derivative as a polymerizable probe to follow the reactions that are taking places in both phases. PMID:27213038

Zeolitic imidazolate framework-methacrylate composite monolith characterization by inverse gas chromatography.

PubMed

Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; Aouak, Taieb; ALOthman, Zeid Abdullah

2016-04-22

Thermodynamic characterization of butyl methacrylate-co-ethylene dimethacrylate neat monolith and zeolitic imidazolate framework-8 incorporated with butyl methacrylate-co-ethylene dimethacrylate composite monolith were studied using inverse gas chromatography at infinite dilution under 1MPa column pressure and various column temperatures. The free energy of adsorption (ΔGA), enthalpy of adsorption (ΔHA) and entropy of adsorption (ΔSA) were determined using a series of n-alkanes. The dispersive component of surface energy (γS(D)) was estimated by Dorris-Gray and Schultz et al. The composite monolith showed a more energetic surface than the neat monolith. The acidic, KA, and basic, KD, parameters for both materials were estimated using a group of polar probes. A basic character was concluded with more basic behavior for the neat monolith. Flory-Huggins parameter, χ, was taken as a measure of miscibility between the probes with the low molecular weight and the high molecular weight monolith. Inverse gas chromatography provides a better understanding of the role of incorporated zeolitic imidazolate framework (ZIF-8) into the polymer matrix in its monolithic form. Copyright © 2016 Elsevier B.V. All rights reserved.

The rational design of recognitive polymeric networks for sensing applications

NASA Astrophysics Data System (ADS)

Noss, Kimberly Ryanne Dial

Testosterone recognitive networks were synthesized with varying feed crosslinking percentages and length of the bi-functional crosslinking agent to analyze the effect of changing structural parameters on template binding properties such as affinity, selectivity, capacity, and diffusional transport. The crosslinking percentage of the crosslinking monomer ethylene glycol dimethacrylate was varied from 50% to 90% and associated networks experienced a 2 fold increase in capacity and a 4 fold increase in affinity with the equilibrium association constants, Ka, ranging from 0.32 +/- 0.02 x 10 4 M-1 to 1.3 +/- 0.1 x 104 M -1, respectively. The higher concentration of crosslinking monomer increased the crosslinking points available for inter-chain stabilization creating an increased number of stable cavities for template association. However, by increasing the length of the crosslinking agent and increasing the feed crosslinking percentage from 77% crosslinked poly(methacrylic acid- co-ethylene glycol dimethacrylate) (poly(MAA-co-EGDMA)) to 50% crosslinked poly(methacrylic acid-co-poly(ethylene glycol)200 dimethacrylate) (poly(MAA-co-PEG200DMA)), the mesh size of the network increased resulting in an increased template diffusion coefficient from (2.83 +/- 0.06) x 109 cm2/s to (4.3 +/- 0.06) x 109 cm2/s, respectively, which is approximately a 40% faster template diffussional transport. A 77% crosslinked poly (MAA-co-PEG200DMA) recognitive network had an association constant of (0.20 +/- 0.05) x 104 M -1 and bound (0.72 +/- 0.04) x 10-2 mmol testosterone/g dry polymer, which was less by 6 and 3 fold, respectively, compared to a similarly crosslinked poly(MAA-co-EGDMA) recognitive network. Structural manipulation of the macromolecular architecture illustrates the programmability of recognitive networks for specific template binding parameters and diffusional transport, which may lead to enhanced imprinted sensor materials and successful integration onto sensor platforms.

Novel dental adhesive with triple benefits of calcium phosphate recharge, protein-repellent and antibacterial functions.

PubMed

Xie, Xianju; Wang, Lin; Xing, Dan; Zhang, Ke; Weir, Michael D; Liu, Huaibing; Bai, Yuxing; Xu, Hockin H K

2017-05-01

A new adhesive containing nanoparticles of amorphous calcium phosphate (NACP) with calcium (Ca) and phosphate (P) ion rechargeability was recently developed; however, it was not antibacterial. The objectives of this study were to: (1) develop a novel adhesive with triple benefits of Ca and P ion recharge, protein-repellent and antibacterial functions via dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC); and (2) investigate dentin bond strength, protein adsorption, Ca and P ion concentration, microcosm biofilm response and pH properties. MPC, DMAHDM and NACP were mixed into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA), pyromellitic glycerol dimethacrylate (PMGDM), 2-hydroxyethyl methacrylate (HEMA) and bisphenol A glycidyl dimethacrylate (BisGMA). Protein adsorption was measured using a micro bicinchoninic acid method. A human saliva microcosm biofilm model was tested on resins. Colony-forming units (CFU), live/dead assay, metabolic activity, Ca and P ion concentration and biofilm culture medium pH were determined. The adhesive with 5% MPC+5% DMAHDM+30% NACP inhibited biofilm growth, reducing biofilm CFU by 4 log, compared to control (p<0.05). Dentin shear bond strengths were similar (p>0.1). Biofilm medium became a Ca and P ion reservoir having ion concentration increasing with NACP filler level. The adhesive with 5% MPC+5% DMAHDM+30% NACP maintained a safe pH>6, while commercial adhesive had a cariogenic pH of 4. The new adhesive with triple benefits of Ca and P ion recharge, protein-repellent and antibacterial functions substantially reduced biofilm growth, reducing biofilm CFU by 4 orders of magnitude, and yielding a much higher pH than commercial adhesive. This novel adhesive is promising to protect tooth structures from biofilm acids. The method of using NACP, MPC and DMAHDM is promising for application to other dental materials to combat caries. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres.

PubMed

Ozakar Ilday, Nurcan; Celik, Neslihan; Bayindir, Yusuf Ziya; Seven, Nilgün

2014-06-01

The purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. Two light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24 h, 168 h and 504 h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). The highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). Within the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. Considering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Preparation of a novel sorptive stir bar based on vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer for the simultaneous extraction of diazepam and nordazepam from human plasma.

PubMed

Torabizadeh, Mahsa; Talebpour, Zahra; Adib, Nuoshin; Aboul-Enein, Hassan Y

2016-04-01

A new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The polymerization step was performed using different contents of monomer, cross-linker and porogenic solvent, and the best formulation was selected. The quality of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate stir bars was satisfactory, demonstrating good repeatability within batch (relative standard deviation < 3.5%) and acceptable reproducibility between batches (relative standard deviation < 6.0%). The prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of diazepam and nordazepam in human plasma samples. To optimize the extraction step, a three-level, four-factor, three-block Box-Behnken design was applied. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for diazepam (36-1200 ng/mL) and nordazepam (25-1200 ng/mL), with correlation coefficients of 0.9986 and 0.9968 and detection limits of 12 and 10 ng/mL, respectively. The intra- and interday recovery ranged from 93 to 106%, and the relative standard deviations were less than 6%. Finally, the proposed method was successfully applied to the analysis of diazepam and nordazepam at their therapeutic levels in human plasma. The novelty of this study is the improved polarity of the stir bar coating and its application for the simultaneous extraction of diazepam and its active metabolite, nordazepam in human plasma sample. The method was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of diazepam and nordazepam in biological fluids. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Contact dermatitis caused by acrylates among 8 workers in an elevator factory].

PubMed

Pérez-Formoso, J L; de Anca-Fernández, J; Maraví-Cecilia, R; Díaz-Torres, J M

2010-05-01

Acrylates are widely used low-molecular-weight substances, initially introduced in industry in the 1930s and subsequently applied also in medicine and the home. One of their main features is the ability to undergo polymerization. The most commonly used acrylic compounds are cyanoacrylates, methacrylates, and acrylates. To confirm suspicion of occupational disease in a group of workers in an elevator factory. We studied 8 patients with dermatitis of the hands and finger pads. In their work, the patients came into contact with acrylates. Patch testing was applied with an acrylate panel (BIAL-Aristegui, Bilbao, Spain). Seven of the patients (87. 5%) had a positive result with 1% ethylene glycol dimethacrylate. Positive were also observed for 2% hydroxyethyl methacrylate (5 patients, 62. 5%), 1% triethylene glycol dimethacrylate (4 patients, 50%), 10% ethyl methacrylate monomer (3 patients, 37. 5%), 10% methyl methacrylate monomer (2 patients, 25%), 1% ethyl acrylate (1 patient, 12. 5%), and 0. 1% acrylic acid (1 patient, 12. 5%). We highlight the strong sensitizing capacity of acrylates and the importance of taking all necessary preventive measures in industries where these substances are used. Such measures should include avoidance of contact with the product in cases where sensitization has been confirmed.

One-pot synthesis of zeolitic imidazolate framework-8/poly (methyl methacrylate-ethyleneglycol dimethacrylate) monolith coating for stir bar sorptive extraction of phytohormones from fruit samples followed by high performance liquid chromatography-ultraviolet detection.

PubMed

You, Linna; He, Man; Chen, Beibei; Hu, Bin

2017-11-17

In this work, zeolitic imidazolate framework-8 (ZIF-8)/poly (methyl methacrylate-ethyleneglycol dimethacrylate) (MMA-EGDMA) composite monolith was in situ synthesized on stir bar by one-pot polymerization. Compared with the neat monolith, ZIF-8/poly(MMA-EGDMA) composite monolith has larger surface area and pore volume. It also exhibits higher extraction efficiency for target phytohormones than poly(MMA-EGDMA) monolith and commercial polyethylene glycol (PEG) coated stir bar. Based on it, a method of ZIF-8/poly(MMA-EGDMA) monolith coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the analysis of five phytohormones in apple and pear samples. The developed method exhibited low limits of detection (0.11-0.51μg/L), wide linear range (0.5-500μg/L) and good recoveries (82.7-111%), which demonstrated good application potential of the ZIF-8/monolith coated stir bar in trace analysis of organic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Enzyme immobilization techniques on poly(glycidyl methacrylate-co-ethylene dimethacrylate) carrier with penicillin amidase as model.

PubMed

Drobník, J; Saudek, V; Svec, F; Kálal, J; Vojtísek, V; Bárta, M

1979-08-01

Two types of bead-form macroporous carriers based on glycidyl methacrylate with ethylene dimethacrylate copolymers were used for the immobilization of penicillin amidase either directly or after chemical modification. Direct binding through oxirane groups, which is equally efficient at pH 4.2 and 7, is relatively slow and brings about an activity loss at low enzyme concentrations. The most efficient immobilization was achieved on glutaraldehyde-activated amino carrier, irrespective of whether the amino groups were formed by ammonia or 1,6-diaminohexane treatment of the original oxirane carrier. Hydrazine treatment gave lower immobilization yields. The same is true of the azide method independent of the length of the spacer. Most enzyme activity was preserved by coupling the carbodiimide-activated enzyme to the carrier with alkyl or arylamino groups at the end of a longer substituent. Immobilization on diazo-modified carrier gave average results. Rapid immobilization by a lysine-modified phosgene-treated carrier resulted in an activity loss. It is suggested that multipoint and very tight attachment of the enzyme molecule to the matrix decreased the activity. The immobilized activity is quite stable in solution and very stable upon lyophilization with sucrose.

Application of an Addition-Fragmentation-Chain Transfer Monomer in Di(meth)acrylate Network Formation to Reduce Polymerization Shrinkage Stress.

PubMed

Shah, Parag K; Stansbury, Jeffrey W; Bowman, Christopher N

2017-08-14

A new addition-fragmentation chain transfer (AFT) capable moiety was incorporated into a dimethacrylate monomer that participated readily in network formation by copolymerizing with multifunctional methacrylates or acrylates. The process of AFT occurred simultaneously with photopolymerization of the AFT monomer (AFM) and other (meth)acrylate monomers leading to polymer stress relaxation via network reconfiguration. At low loading levels of the AFM, a significant reduction in shrinkage stress, especially for acrylate monomers, was observed with nominal effects on conversion. At higher loading levels of the AFM, the photopolymerization reaction kinetics and final double bond conversion were significantly lowered along with a delay in the gel-point conversion. Electron paramagnetic resonance studies during polymerization revealed the presence of a distinct radical species that was present in proportional quantities to the AFM content in the system. The lifetime and the character of the persistent radicals were altered due to the presence of the distinctive radical, in turn affecting the polymerization kinetics. With polymerization conducted at higher irradiance, the differential conversion between the control resin and samples with moderate AFM content was minimal, especially for the methacrylate-based formulations.

Polymerization Behavior of Hydrophilic-Rich Phase of Dentin Adhesive

PubMed Central

Abedin, F.; Parthasarathy, R.; Misra, A.; Spencer, P.

2015-01-01

The 2-fold objectives of this study were 1) to understand whether model hydrophobic- and hydrophilic-rich phase mimics of dentin adhesive polymerize similarly and 2) to determine which factor, the dimethacrylate component, bisphenol A glycerolate dimethacrylate (BisGMA) or photoinitiator concentration, has greater influence on the polymerization of the hydrophilic-rich phase mimic. Current dentin adhesives are sensitive to moisture, as evidenced by nanoleakage in the hybrid layer and phase separation into hydrophobic- and hydrophilic-rich phases. Phase separation leads to limited availability of the cross-linkable dimethacrylate monomer and hydrophobic photoinitiators within the hydrophilic-rich phase. Model hydrophobic-rich phase was prepared as a single-phase solution by adding maximum wt% deuterium oxide (D2O) to HEMA/BisGMA neat resins containing 45 wt% 2-hydroxyethyl methacrylate (HEMA). Mimics of the hydrophilic-rich phase were prepared similarly but using HEMA/BisGMA neat resins containing 95, 99, 99.5, and 100 wt% HEMA. The hydrophilic-rich mimics were prepared with standard or reduced photoinitiator content. The photoinitiator systems were camphorquinone (CQ)/ethyl 4-(dimethylamino)benzoate (EDMAB) with or without [3-(3, 4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-2-hydroxypropyl]trimethylammonium chloride (QTX). The polymerization kinetics was monitored using a Fourier transform infrared spectrophotometer with a time-resolved collection mode. The hydrophobic-rich phase exhibited a significantly higher polymerization rate compared with the hydrophilic-rich phase. Postpolymerization resulting in the secondary rate maxima was observed for the hydrophilic-rich mimic. The hydrophilic-rich mimics with standard photoinitiator concentration but varying cross-linker (BisGMA) content showed postpolymerization and a substantial degree of conversion. In contrast, the corresponding formulations with reduced photoinitiator concentrations exhibited lower polymerization and inhibition/delay of postpolymerization within 2 h. Under conditions relevant to the wet, oral environment, photoinitiator content plays an important role in the polymerization of the hydrophilic-rich phase mimic. Since the hydrophilic-rich phase is primarily water and monomethacrylate monomer (e.g., HEMA as determined previously), substantial polymerization is important to limit the potential toxic response from HEMA leaching into the surrounding tissues. PMID:25576471

Effect of layer thickness on the elution of bulk-fill composite components.

PubMed

Rothmund, Lena; Reichl, Franz-Xaver; Hickel, Reinhard; Styllou, Panorea; Styllou, Marianthi; Kehe, Kai; Yang, Yang; Högg, Christof

2017-01-01

An increment layering technique in a thickness of 2mm or less has been the standard to sufficiently convert (co)monomers. Bulk fill resin composites were developed to accelerate the restoration process by enabling up to 4mm thick increments to be cured in a single step. The aim of the present study is to investigate the effect of layer thickness on the elution of components from bulk fill composites. The composites ELS Bulk fill, SDR Bulk fill and Venus Bulkfill were polymerized according to the instruction of the manufacturers. For each composite three groups with four samples each (n=4) were prepared: (1) samples with a layer thickness of 2mm; (2) samples with a layer thickness of 4mm and (3) samples with a layer thickness of 6mm. The samples were eluted in methanol and water for 24h and 7 d. The eluates were analyzed by gas chromatography/mass spectrometry (GC/MS). A total of 11 different elutable substances have been identified from the investigated composites. Following methacrylates showed an increase of elution at a higher layer thickness: TEGDMA (SDR Bulk fill, Venus Bulk fill), EGDMA (Venus Bulk fill). There was no significant difference in the elution of HEMA regarding the layer thickness. The highest concentration of TEGDMA was 146μg/mL for SDR Bulk fill at a layer thickness of 6mm after 7 d in water. The highest HEMA concentration measured at 108μg/mL was detected in the methanol eluate of Venus Bulk fill after 7 d with a layer thickness of 6mm. A layer thickness of 4mm or more can lead to an increased elution of some bulk fill components, compared to the elution at a layer thickness of 2mm. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

On the degelation of networks – Case of the radiochemical degradation of methyl methacrylate – ethylene glycol dimethacrylate copolymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richaud, Emmanuel; Gilormini, Pierre; Verdu, Jacques

2016-05-18

Methyl methacrylate networks were synthetized and submitted to radiochemical degradation. Ageing was monitored by means of sol-gel analysis and glass transition temperature measurements. Networks were shown to undergo exclusively chain scission process leading to the degelation of network. The critical conversion degree corresponding to degelation (loss of all elastically active chains) is discussed regarding a statistical theory.

CEC-atmospheric pressure ionization MS of pesticides using a surfactant-bound monolithic column.

PubMed

Gu, Congying; Shamsi, Shahab A

2010-04-01

A surfactant bound poly (11-acrylaminoundecanoic acid-ethylene dimethacrylate) monolithic column was simply prepared by in situ co-polymerization of 11-acrylaminoundecanoic acid and ethylene dimethacrylate with 1-propanol, 1,4-butanediol and water as porogens in 100 microm id fused-silica capillary in one step. This column was used in CEC-atmospheric pressure photoionization (APPI)-MS system for separation and detection of N-methylcarbamates pesticides. Numerous parameters are optimized for CEC-APPI-MS. After evaluation of the mobile phase composition, sheath liquid composition and the monolithic capillary outlet position, a fractional factorial design was selected as a screening procedure to identify factors of ionization source parameters, such as sheath liquid flow rate, drying gas flow rate, drying gas temperature, nebulizing gas pressure, vaporizer temperature and capillary voltage, which significantly influence APPI-MS sensitivity. A face-centered central composite design was further utilized to optimize the most significant parameters and predict the best sensitivity. Under optimized conditions, S/Ns around 78 were achieved for an injection of 100 ng/mL of each pesticide. Finally, this CEC-APPI-MS method was successfully applied to the analysis of nine N-methylcarbamates in spiked apple juice sample after solid phase extraction with recoveries in the range of 65-109%.

Separation of alpha-, beta-, gamma-, delta-tocopherols and alpha-tocopherol acetate on a pentaerythritol diacrylate monostearate-ethylene dimethacrylate monolith by capillary electrochromatography.

PubMed

Chaisuwan, Patcharin; Nacapricha, Duangjai; Wilairat, Prapin; Jiang, Zhengjin; Smith, Norman W

2008-06-01

This work reports the first use of a monolith with method development for the separation of tocopherol (TOH) compounds by CEC with UV detection. A pentaerythritol diacrylate monostearate-ethylene dimethacrylate (PEDAS-EDMA) monolithic column has been investigated for an optimised condition to separate alpha-, beta-, gamma- and delta-TOHs, and alpha-tocopherol acetate (TAc). The PEDAS-EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the beta- and gamma-isomers which are not easily separated by standard C8 or C18 particle-packed columns. Retention studies indicated that an RP mechanism was involved in the separation on the PEDAS-EDMA column, but polar interactions with the underlying ester and hydroxyl groups enhanced the separation of the problematic beta- and gamma-isomers. Separation of all the compounds was achieved within 25 min using 3:10:87 v/v/v 100 mM Tris buffer (pH 9.3)/methanol/ACN as the mobile phase. The method was successfully applied to a pharmaceutical sample with recoveries from 93 to 99%. Intraday and interday precisions (%RSD) for peak area and retention time were less than 2.3. LODs for all four TOHs and TAc were below 1 ppm.

Rechargeable dental adhesive with calcium phosphate nanoparticles for long-term ion release

PubMed Central

Zhang, Ling; Weir, Michael D.; Hack, Gary; Fouad, Ashraf F.; Xu, Hockin H. K.

2015-01-01

Objectives The tooth-resin bond is the weak link of restoration, with secondary caries as a main reason for failure. Calcium phosphate-containing resins are promising for remineralization; however, calcium (Ca) and phosphate (P) ion releases last only a couple of months. The objectives of this study were to develop the first rechargeable CaP bonding agent and investigate the key factors that determine CaP ion recharge and re-release. Methods Nanoparticles of amorphous calcium phosphate (NACP) were synthesized. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA), and bisphenol-A glycidyl dimethacrylate (BisGMA) were used to synthesize three adhesives (denoted PE, PEH and PEHB). NACP were mixed into adhesive at 0–30% by mass. Dentin shear bond strengths were measured. Adhesive specimens were tested for Ca and P initial ion release. Then the ion-exhausted specimens were immersed in Ca and P solution to recharge the specimens, and the recharged specimens were then used to measure ion re-release for 7 days as one cycle. Then these specimens were again recharged and the re-release was measured for 7 days as the second cycle. Three recharge/re-release cycles were tested. Results PEHB had the highest dentin bond strength (p<0.05). Increasing NACP content from 0 to 30% did not affect dentin bond strength (p>0.1), but increased CaP release and re-release (p<0.05). PEHB-NACP had the greatest recharge/re-release, and PE-NACP had the least (p<0.05). Ion release remained high and did not decrease with increasing the number of recharge/re-release cycles (p>0.1). After the third cycle, specimens without further recharge had continuous CaP ion release for 2–3 weeks. Significance Rechargeable CaP bonding agents were developed for the first time to provide long-term Ca and P ions to promote remineralization and reduce caries. Incorporation of NACP into adhesive had no negative effect on dentin bond strength. Increasing NACP filler level increased the ion recharge and re-release capability. The new CaP recharge method and PMGDM-EBPAGMA-NACP composition may have wide application in adhesives, composites and cements, to combat caries and remineralize lesions. PMID:26144190

End-Group Effects on the Properties of PEG-co-PGA Hydrogels

PubMed Central

Bencherif, Sidi A.; Srinivasan, Abiraman; Sheehan, Jeffrey A.; Walker, Lynn M.; Gayathri, Chakicherla; Gil, Roberto; Hollinger, Jeffrey O.; Matyjaszewski, Krzysztof; Washburn, Newell R.

2009-01-01

A series of resorbable poly(ethylene glycol)-co-poly(glycolic acid) macromonomers have been synthesized with the chemistries from three different photopolymerizable end-groups (acrylates, methacrylates, and urethane methacrylates). The aim of the study is to examine the effects of the chemistry of the cross-linker group on the properties of photocross-linkable hydrogels. PEG-co-PGA (4KG5) hydrogels were prepared by photopolymerization with high vinyl group conversion as confirmed by 1H NMR spectroscopy using DOSY 1D pulse sequence. Our study reveals that the nature of end-groups in a moderately amphiphilic polymer can adjust the distribution and size of the micellar configuration in water leading to changes in the macroscopic structure of hydrogels. By varying the chemistry of the cross-linker group (diacrylates; DA, dimethacrylates; DM, and urethane dimethacrylates; UDM), we determined that the hydrophobocity of a single core polymer consisting of poly(glycolic acid) could be fine-tuned leading to significant variations in the mechanical, swelling, and degradation properties of the gels. In addition, the effects of cross-linker chemistry on cytotoxicity and proliferation were examined. Cytotoxicity assays showed that all the three types of hydrogels (4KG5 DA, DM, and UDM) were biocompatible and the introduction of RGD ligand enhanced cell adhesion. However, differences in gel properties and stability differentially affected the spreading and proliferation of myoblast C2C12 cells. PMID:19328754

Comparison of a new bisphenol-a-glycidyl dimethacrylate-based cortical bone void filler with polymethyl methacrylate.

PubMed

Erbe, E M; Clineff, T D; Gualtieri, G

2001-10-01

A newly formulated and reinforced bisphenol-a-glycidyl dimethacrylate (bis-GMA) resin (Cortoss/Orthovita, Malvern, Pa.) was compared with Simplex P polymethyl methacrylate (Stryker Howmedica Osteonics, East Rutherford, N.J.) in rabbits for up to 52 weeks and in sheep for up to 78 weeks. As seen in scanning electron microscopy and histology examinations, both implant materials were surrounded by bone at late time periods, with fibrous layers of connective tissue seen in half the Simplex P specimens. No clinically significant safety differences between implant materials were apparent. Interfacial bond strengths between the implant and bone generally increased with time, but were 4.5-fold greater with Cortoss than Simplex P at 24 weeks, and 100-fold greater at 52 weeks. Forces required to displace 316SS rods held in place with Cortoss were consistently greater than forces to displace rods held in place with Simplex P. No statistically significant differences in displacement forces were found between rods held in place with Cortoss polymerized in situ and rods held with prepolymerized Cortoss. Interfacial bond strengths were greater for Simplex P that was polymerized in situ than for prepolymerized polymethyl methacrylate specimens. Cortoss synthetic cortical bone void filler is a good candidate material to fix implants in bone. It has characteristics consistent with long-term safety and has a better ability to bond to bone than Simplex P.

Adsorption induced enzyme denaturation: the role of protein surface in adsorption induced protein denaturation on allyl glycidyl ether (AGE)-ethylene glycol dimethacrylate (EGDM) copolymers.

PubMed

Thudi, Lahari; Jasti, Lakshmi S; Swarnalatha, Y; Fadnavis, Nitin W; Mulani, Khudbudin; Deokar, Sarika; Ponrathnam, Surendra

2012-02-01

The effects of protein size on adsorption and adsorption-induced denaturation of proteins on copolymers of allyl glycidyl ether (AGE)-ethylene glycol dimethacrylate (EGDM) have been studied. Different responses were observed for the amount of protein adsorbed and denatured on the polymer surface for different proteins (trypsin, alchol dehydrogenase from baker's yeast (YADH), glucose dehydrogenase (GDH) from Gluconobacter cerinus, and alkaline phosphates from calf intestinal mucosa (CIAP). Protein adsorption on the copolymer with 25% crosslink density (AGE-25) was dependent not only on the size of the protein but also on the presence of glycoside residues on the protein surface. Adsorption and denaturation of proteins follows the order YADH>trypsin>GDH>CIAP although the molecular weights of the proteins follow the order YADH>CIAP>GDH>trypsin. The lack of correlation between amount of adsorbed protein and its molecular weight was due to the presence of glycoside residues on CIAP and GDH which protect the enzyme surface from denaturation. Enzyme stabilities in aqueous solutions of 1-cyclohexyl-2-pyrrolidinone (CHP) correlate well with the trend in denaturation by the copolymer, strongly suggesting that hydrophobic interactions play a major role in protein binding and the mechanism of protein denaturation is similar to that for water-miscible organic solvents. Copyright © 2011 Elsevier B.V. All rights reserved.

Drug loading optimization and extended drug delivery of corticoids from pHEMA based soft contact lenses hydrogels via chemical and microstructural modifications.

PubMed

García-Millán, Eva; Koprivnik, Sandra; Otero-Espinar, Francisco Javier

2015-06-20

This paper proposes an approach to improve drug loading capacity and release properties of poly(2-hydroxyethyl methacrylate) (p(HEMA)) soft contact lenses based on the optimization of the hydrogel composition and microstructural modifications using water during the polymerization process. P(HEMA) based soft contact lenses were prepared by thermal or photopolymerization of 2-hydroxyethyl methacrylate (HEMA) solutions containing ethylene glycol di-methacrylate as crosslinker and different proportions of N-vinyl-2-pyrrolidone (NVP) or methacrylic acid (MA) as co-monomers. Transmittance, water uptake, swelling, microstructure, drug absorption isotherms and in vitro release were characterized using triamcinolone acetonide (TA) as model drug. Best drug loading ratios were obtained with lenses containing the highest amount (200 mM) of MA. Incorporation of 40% V/V of water during the polymerization increases the hydrogel porosity giving a better drug loading capacity. In vitro TA release kinetics shows that MA hydrogels released the drug significantly faster than NVP-hydrogels. Drug release was found to be diffusion controlled and kinetics was shown to be reproducible after consecutive drug loading/release processes. Results of p(HEMA) based soft contact lenses copolymerized with ethylene glycol dimethacrylate (EGDMA) and different co-monomers could be a good alternative to optimize the loading and ocular drug delivery of this corticosteroid drug. Copyright © 2015. Published by Elsevier B.V.

Development of molecularly imprinted polymer in porous film format for binding of phenol and alkylphenols from water.

PubMed

Gryshchenko, Andriy O; Bottaro, Christina S

2014-01-20

Molecularly imprinted polymers (MIPs) were fabricated on glass slides with a "sandwich" technique giving ~20 µm thick films. Methanol/water as a solvent, and polyethyleneglycol and polyvinylacetate as solvent modifiers, were used to give a porous morphology, which was studied with scanning electron microscopy and gravimetric analysis. Various MIPs were synthesized through non-covalent imprinting with phenol as the template; itaconic acid, 4-vinylpyridine, and styrene as monomers; ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and pentaerythritol triacrylate (PETA) as cross-linkers. Binding and imprinting properties of the MIPs were evaluated based on phenol adsorption isotherms. Since phenol has only one weakly acidic hydroxyl group and lacks unique structural characteristics necessary for binding specificity, the preparation of selective MIPs was challenging. The recognition of phenol via hydrogen bonding is suppressed in water, while hydrophobic interactions, though promoted, are not specific enough for highly-selective phenol recognition. Nevertheless, the styrene-PETA MIP gave modest imprinting effects, which were higher at lower concentrations (Imprinting Factor (IF) = 1.16 at 0.5 mg·L(-1)). The isotherm was of a Freundlich type over 0.1-40 mg·L(-1) and there was broad cross-reactivity towards other structurally similar phenols. This shows that phenol MIPs or simple adsorbents can be developed based on styrene for hydrophobic binding, and PETA to form a tighter, hydrophilic network.

A Study of Shrinkage Stress Reduction and Mechanical Properties of Nanogel-Modified Resin Systems

PubMed Central

Liu, JianCheng; Howard, Gregory D.; Lewis, Steven H.; Barros, Matthew D.; Stansbury, Jeffrey W.

2012-01-01

A series of nanogel compositions were prepared from urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The linear oligomer of IBMA was synthesized by a similar solution polymerization technique. The nanogels were prepared with different crosslinker concentrations to achieve varied branching densities and molecular weights. The prepolymers were dispersed in triethylene glycol dimethacrylate at loading levels ranging from 10 wt% to 50 wt%. Photopolymerization reaction kinetics of all prepolymer modified systems were enhanced relative to the nanogel-free control during early stage polymerization while limiting conversion was similar for most samples. Volumetric polymerization shrinkage was reduced proportionally with the prepolymer content while the corresponding decrease in polymerization stress was potentially greater than an additive linear behavior. Flexural strength for inert linear polymer-modified systems decreased significantly with the increase in the prepolymer content; however, with an increase in the crosslinker concentration within the nanogel additives, and an increase in the concentration of residual pendant reactive sites, flexural strength was maintained or improved regardless of the nanogel loading level. This demonstrates that covalent attachment rather than just physical entanglement with the polymer matrix is important for effective polymer mechanical reinforcement by nanogel additives. Reactive nanogel additives can be considered as a practical, generic means to achieve substantial reductions in polymerization shrinkage and shrinkage stress in common polymers. PMID:23109731

Thio-urethanes improve properties of dual-cured composite cements.

PubMed

Bacchi, A; Dobson, A; Ferracane, J L; Consani, R; Pfeifer, C S

2014-12-01

This study aims at modifying dual-cure composite cements by adding thio-urethane oligomers to improve mechanical properties, especially fracture toughness, and reduce polymerization stress. Thiol-functionalized oligomers were synthesized by combining 1,3-bis(1-isocyanato-1-methylethyl)benzene with trimethylol-tris-3-mercaptopropionate, at 1:2 isocyanate:thiol. Oligomer was added at 0, 10 or 20 wt% to BisGMA-UDMA-TEGDMA (5:3:2, with 25 wt% silanated inorganic fillers) or to one commercial composite cement (Relyx Ultimate, 3M Espe). Near-IR was used to measure methacrylate conversion after photoactivation (700 mW/cm(2) × 60s) and after 72 h. Flexural strength and modulus, toughness, and fracture toughness were evaluated in three-point bending. Polymerization stress was measured with the Bioman. The microtensile bond strength of an indirect composite and a glass ceramic to dentin was also evaluated. Results were analyzed with analysis of variance and Tukey's test (α = 0.05). For BisGMA-UDMA-TEGDMA cements, conversion values were not affected by the addition of thio-urethanes. Flexural strength/modulus increased significantly for both oligomer concentrations, with a 3-fold increase in toughness at 20 wt%. Fracture toughness increased over 2-fold for the thio-urethane modified groups. Contraction stress was reduced by 40% to 50% with the addition of thio-urethanes. The addition of thio-urethane to the commercial cement led to similar flexural strength, toughness, and conversion at 72h compared to the control. Flexural modulus decreased for the 20 wt% group, due to the dilution of the overall filler volume, which also led to decreased stress. However, fracture toughness increased by up to 50%. The microtensile bond strength increased for the experimental composite cement with 20 wt% thio-urethane bonding for both an indirect composite and a glass ceramic. Novel dual-cured composite cements containing thio-urethanes showed increased toughness, fracture toughness and bond strength to dentin while demonstrating reduced contraction stress. All of these benefits are derived without compromising the methacrylate conversion of the resin component. The modification does not require changing the operatory technique. © International & American Associations for Dental Research.

Thio-urethanes Improve Properties of Dual-cured Composite Cements

PubMed Central

Bacchi, A.; Dobson, A.; Ferracane, J.L.; Consani, R.; Pfeifer, C.S.

2014-01-01

This study aims at modifying dual-cure composite cements by adding thio-urethane oligomers to improve mechanical properties, especially fracture toughness, and reduce polymerization stress. Thiol-functionalized oligomers were synthesized by combining 1,3-bis(1-isocyanato-1-methylethyl)benzene with trimethylol-tris-3-mercaptopropionate, at 1:2 isocyanate:thiol. Oligomer was added at 0, 10 or 20 wt% to BisGMA-UDMA-TEGDMA (5:3:2, with 25 wt% silanated inorganic fillers) or to one commercial composite cement (Relyx Ultimate, 3M Espe). Near-IR was used to measure methacrylate conversion after photoactivation (700 mW/cm2 × 60s) and after 72 h. Flexural strength and modulus, toughness, and fracture toughness were evaluated in three-point bending. Polymerization stress was measured with the Bioman. The microtensile bond strength of an indirect composite and a glass ceramic to dentin was also evaluated. Results were analyzed with analysis of variance and Tukey’s test (α = 0.05). For BisGMA-UDMA-TEGDMA cements, conversion values were not affected by the addition of thio-urethanes. Flexural strength/modulus increased significantly for both oligomer concentrations, with a 3-fold increase in toughness at 20 wt%. Fracture toughness increased over 2-fold for the thio-urethane modified groups. Contraction stress was reduced by 40% to 50% with the addition of thio-urethanes. The addition of thio-urethane to the commercial cement led to similar flexural strength, toughness, and conversion at 72h compared to the control. Flexural modulus decreased for the 20 wt% group, due to the dilution of the overall filler volume, which also led to decreased stress. However, fracture toughness increased by up to 50%. The microtensile bond strength increased for the experimental composite cement with 20 wt% thio-urethane bonding for both an indirect composite and a glass ceramic. Novel dual-cured composite cements containing thio-urethanes showed increased toughness, fracture toughness and bond strength to dentin while demonstrating reduced contraction stress. All of these benefits are derived without compromising the methacrylate conversion of the resin component. The modification does not require changing the operatory technique. PMID:25248610

Preparation and Properties of Hybrid Nanostructures of Zinc Tetraphenylporphyrinate and an Amphiphilic Copolymer of N-Vinylpyrrolidone in a Neutral Aqueous Buffer Solution

NASA Astrophysics Data System (ADS)

Kurmaz, S. V.; Gak, V. Yu.; Kurmaz, V. A.; Konev, D. V.

2018-02-01

Water-soluble forms of a hydrophobic dye, zinc tetraphenylporphyrinate, are obtained via its solubilization by polymer particles of the micellar type formed by a copolymer of N-vinylpyrrolidone with triethylene glycol dimethacrylate. Hydrodynamic radii R h and the size distribution of such particles in neutral aqueous buffer solutions are determined via dynamic light scattering. The electrochemical activity of the encapsulated dye is found, and its photochemical properties (absorption and fluorescence) are studied.

Tensile Properties of Poly (N-vinyl caprolactam) Gels

NASA Technical Reports Server (NTRS)

Morgret, Leslie D.; Hinkley, Jeffrey A.

2004-01-01

N-vinyl caprolactam was copolymerized with ethylene glycol dimethacrylate using a free-radical initiator in alcohol/water solution. The resulting gels were thermally-responsive in water, undergoing an approximate fivefold reversible volume shrinkage between room temperature and ca. 50 C. Tensile testing showed that the stress-strain behavior was qualitatively different in the collapsed state above the temperature-induced transition. At the higher temperature, gels were stiffer, more ductile, and showed greater time dependence. Implications for the design of gel actuators are briefly discussed.

Polymer sorbent with the properties of an artificial cholesterol receptor

NASA Astrophysics Data System (ADS)

Polyakova, I. V.; Ezhova, N. M.; Osipenko, A. A.; Pisarev, O. A.

2015-02-01

A cholesterol-imprinted polymer sorbent and the corresponding reticular control copolymer were synthesized from hydroxyethyl methacrylate and ethyleneglycol dimethacrylate. The sorption isotherms of cholesterol were analyzed using the generalized Langmuir and Freundlich equations. In the case of the imprinted reticular polymer, cholesterol sorption occurred on the energetically homogeneous binding centers, forming one monolayer, while the nonspecific sorption of cholesterol on the control copolymer occurred with energetically nonhomogeneous binding of the sorbate and depended on the physicochemical conditions of sorption.

In situ reactive compatibilization of polypropylene/ethylene-propylene-diene monomer thermoplastic vulcanizate by zinc dimethacrylate via peroxide-induced dynamic vulcanization.

PubMed

Chen, Yukun; Xu, Chuanhui; Liang, Xingquan; Cao, Liming

2013-09-12

This work demonstrates an approach of in situ reactive compatibilization between polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) by using zinc dimethacrylate (ZDMA) as a compatibilizer and, simultaneously, as a very strong reinforcing agent. With the incorporation of 7phr ZDMA in the PP/EPDM (30/70, w/w) thermoplastic vulcanizate (TPV), the tensile strength, tear strength, elongation at break, and hardness of PP/EPDM/ZDMA TPV were increased from 5.3 MPa, 31.3 kN/m, 222%, and 78 up to 11.2 MPa, 64.2 kN/m, 396%, and 83, respectively. This tremendous reinforcing as well as the compatibilization effect of the ZDMA was understood by polymerization of ZDMA and ZDMA reacted with EPDM and PP during peroxide-induced dynamic vulcanization. A peculiar phase structure that rubber particles were surrounded and "bonded" by a thick transition zone that contained numerous of nanoparticles with dimensions of about 20-30 nm was observed from transmission electron microscopy. Scanning electron microscopy results confirmed that incorporation of ZDMA reduced the size of the cross-linked EPDM particles. Moreover, we found that the compatibilized TPV showed a higher tan δ peak temperature for EPDM phase and a lower tan δ peak temperature for PP phase. The suggested method for in situ reactive compatibilization of PP and EPDM offers routes to the design of new TPV-based technical products for diversified applications.

Effect of monomer composition of polymer matrix on flexural properties of glass fibre-reinforced orthodontic archwire.

PubMed

Ohtonen, J; Vallittu, P K; Lassila, L V J

2013-02-01

To compare force levels obtained from glass fibre-reinforced composite (FRC) archwires. Specifically, FRC wires were compared with polymer matrices having different dimethacrylate monomer compositions. FRC material (E-glass provided by Stick Tech Ltd, Turku, Finland) with continuous unidirectional glass fibres and four different types of dimethacrylate monomer compositions for the resin matrix were tested. Cross-sectionally round FRC archwires fitting into the 0.3 mm slot of a bracket were divided into 16 groups with six specimens in each group. Glass fibres were impregnated by the manufacturer, and they were initially light-cured by hand light-curing unit or additionally post-cured in light-curing oven. The FRC archwire specimens were tested at 37°C according to a three-point bending test in dry and wet conditions using a span length of 10 mm and a crosshead speed of 1.0 mm/minute. The wires were loaded until final failure. The data were statistically analysed using analysis of variance (ANOVA). The dry FRC archwire specimens revealed higher load values than water stored ones, regardless of the polymer matrix. A majority of the FRC archwires showed higher load values after being post-cured. ANOVA revealed that the polymer matrix, curing method, and water storage had a significant effect (P < 0.05) on the flexural behaviour of the FRC archwire. Polymer matrix composition, curing method, and water storage affected the flexural properties and thus, force level and working range which could be obtained from the FRC archwire.

Permeability of different types of medical protective gloves to acrylic monomers.

PubMed

Lönnroth, Emma-Christin; Wellendorf, Hanne; Ruyter, Eystein

2003-10-01

Dental personnel and orthopedic surgeons are at risk when manually handling products containing methyl methacrylate (MMA). Dental products may also contain cross-linking agents such as ethylene glycol dimethacrylate (EGDMA) or 1,4-butanediol dimethacrylate (1,4-BDMA). Skin contact with monomers can cause hand eczema, and the protection given by gloves manufactured from different types of material is not well known. The aim of this study was to determine the breakthrough time (BTT, min) as a measure of protection (according to the EU standard EN-374-3) for a mixture consisting of MMA, EGDMA and 1,4-BDMA. Fifteen different gloves representing natural rubber latex material, synthetic rubber material (e.g. nitrile rubbers), and synthetic polymer material were tested. The smallest monomer MMA permeated within 3 min through all glove materials. A polyethylene examination glove provided the longest protection period to EGDMA and 1, 4-BDMA (> 120 min and 25.0 min), followed by the surgical glove Tactylon (6.0 min and 8.7 min) and the nitrile glove Nitra Touch (5.0 min and 8.7 min). This study showed that the breakthrough time (based on permeation rate) cannot be regarded as a 'safe limit'. When the permeation rate is low, monomers may have permeated before BTT can be determined. Using double gloves with a synthetic rubber inner glove and a natural rubber outer glove provided longer protection when the inner glove was rinsed in water before placing the outer glove on top.

Two decades of occupational (meth)acrylate patch test results and focus on isobornyl acrylate.

PubMed

Christoffers, Wietske A; Coenraads, Pieter-Jan; Schuttelaar, Marie-Louise A

2013-08-01

Acrylates constitute an important cause of occupational contact dermatitis. Isobornyl acrylate sensitization has been reported in only 2 cases. We encountered an industrial process operator with occupational contact dermatitis caused by isobornyl acrylate. (i) To investigate whether it is relevant to add isobornyl acrylate to the (meth)acrylate test series. (ii) To report patients with (meth)acrylate contact allergy at an occupational dermatology clinic. Our patch test database was screened for positive reactions to (meth)acrylates between 1993 and 2012. A selected group of 14 patients was tested with an isobornyl acrylate dilution series: 0.3%, 0.1%, 0.033%, and 0.01%. Readings were performed on D2, D3, and D7. One hundred and fifty-one patients were tested with our (meth)acrylate series; 24 had positive reactions. Most positive reactions were to 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, and diethyleneglycol diacrylate. Hypothetical screening with 2-hydroxypropyl acrylate, ethyleneglycol dimethacrylate, ethoxylated bisphenol A glycol dimethacrylate and trimethylolpropane triacrylate identified 91.7% of the 24 patients. No positive reactions were observed in 14 acrylate-positive patients tested with the isobornyl acrylate dilution series. The 0.3% isobornyl acrylate concentration induced irritant reactions in 3 patients. We report a rare case of allergic contact dermatitis caused by isobornyl acrylate. However, this study provides insufficient support for isobornyl acrylate to be added to a (meth)acrylate series. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Monolithic column based on a poly(glycidyl methacrylate-co-4-vinylphenylboronic acid-co-ethylene dimethacrylate) copolymer for capillary liquid chromatography of small molecules and proteins.

PubMed

Lin, Zian; Huang, Hui; Sun, Xiaobo; Lin, Yao; Zhang, Lan; Chen, Guonan

2012-07-13

A new polymer monolith with three modes of reverse-phase, hydrophilic and cation-exchange interaction was synthesized in 100 μm i.d. fused-silica capillary by in situ polymerization procedure. The pre-polymerization mixture consisted of glycidyl methacrylate (GMA) and 4-vinylphenylboronic acid (VPBA) as bifunctional monomers, ethylene dimethacrylate (EDMA) as crosslinker, 1,4-butanediol (BDO) and diethylene glycol (DEG) as binary porogenic solvents, and azobisisobutyronitrile (AIBN) as initiator. The resulting poly(GMA-co-VPBA-co-EDMA) monolith showed a relatively homogeneous monolithic structure, good permeability and mechanical stability. Different ratios of monomers and porogens were used for optimizing the properties of monolithic column. The column performance was assessed by the separation of a series of neutral solutes, charge solutes, phenols and anilines. Compared with poly(GMA-co-EDMA) monolith, the proposed monolith exhibited more flexible adjustment of selectivity in terms of hydrophobic, hydrophilic, as well as cation-exchange interaction in the same chromatographic conditions. High column efficiencies for benzene derivatives with 70,000-102,000 theoretical plates/m could be obtained at a linear velocity of 0.265 mm/s. The run-to-run, column-to-column, and batch-to-batch repeatabilities of the retention times were less than 8.23%. Additionally, the purposed monolith was also applied to efficient separation of alkaloids and proteins for demonstrating its potential in biomolecule separation. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Anisotropic piezoresistivity characteristics of aligned carbon nanotube-polymer nanocomposites

NASA Astrophysics Data System (ADS)

Sengezer, Engin C.; Seidel, Gary D.; Bodnar, Robert J.

2017-09-01

Dielectrophoresis under the application of AC electric fields is one of the primary fabrication techniques for obtaining aligned carbon nanotube (CNT)-polymer nanocomposites, and is used here to generate long range alignment of CNTs at the structural level. The degree of alignment of CNTs within this long range architecture is observed via polarized Raman spectroscopy so that its influence on the electrical conductivity and piezoresistive response in both the alignment and transverse to alignment directions can be assessed. Nanocomposite samples consisting of randomly oriented, well dispersed single-wall carbon nanotubes (SWCNTs) and of long range electric field aligned SWCNTs in a photopolymerizable monomer blend (urethane dimethacrylate and 1,6-hexanediol dimethacrylate) are quantitatively and qualitatively evaluated. Piezoresistive sensitivities in form of gauge factors were measured for randomly oriented, well dispersed specimens with 0.03, 0.1 and 0.5 wt% SWCNTs and compared with gauge factors in both the axial and transverse to SWCNT alignment directions for electric field aligned 0.03 wt% specimens under both quasi-static monotonic and cyclic tensile loading. Gauge factors in the axial direction were observed to be on the order of 2, while gauge factors in the transverse direction demonstrated a 5 fold increase with values on the order of 10 for aligned specimens. Based on Raman analysis, it is believed the higher sensitivity of the transverse direction is related to architectural evolution of misaligned bridging structures which connect alignment structures under load due to Poisson’s contraction.

Polymer grafted-magnetic halloysite nanotube for controlled and sustained release of cationic drug.

PubMed

Fizir, Meriem; Dramou, Pierre; Zhang, Kai; Sun, Cheng; Pham-Huy, Chuong; He, Hua

2017-11-01

In this research, novel polymer grafted-magnetic halloysite nanotubes with norfloxacin loaded (NOR-MHNTs) and controlled-release, was achieved by surface-initiated precipitation polymerization. The magnetic halloysite nanotubes exhibited better adsorption of NOR (72.10mgg -1 ) compared with the pristine HNTs (30.80mgg -1 ). Various parameters influencing the drug adsorption of the MHNTs for NOR were studied. Polymer grafted NOR-MHNTs has been designed using flexible docking in computer simulation to choose optimal monomers. NOR-MHNTs/poly (methacrylic acid or acrylamide-co-ethylene glycol dimethacrylate) nanocomposite were synthesized using NOR-MHNTs, methacrylic acid (MAA) or acrylamide (AM), ethylene glycol dimethacrylate (EGDMA) and AIBN as nanotemplate, monomers, cross linker and initiator, respectively. The magnetic nanocomposites were characterized by FTIR, TEM, XRD and VSM. The magnetic nanocomposites show superparamagnetic property and fast magnetic response (12.09emug -1 ). The copolymerization of monomers and cross linker led to a better sustained release of norfloxacin (>60h) due to the strong interaction formed between monomers and this cationic drug. The cumulative release rate of NOR is closely related to the cross linker amount. In conclusion, combining the advantages of the high adsorption capacity and magnetic proprieties of this biocompatible clay nanotube and the advantages of polymer shell in the enhancement of controlled-sustained release of cationic drug, a novel formulation for the sustained-controlled release of bioactive agents is developed and may have considerable potential application in targeting drug delivery system. Copyright © 2017. Published by Elsevier Inc.

Physicochemical Characteristics and Slow Release Performances of Chlorpyrifos Encapsulated by Poly(butyl acrylate-co-styrene) with the Cross-Linker Ethylene Glycol Dimethacrylate.

PubMed

Wang, Yu; Gao, Zideng; Shen, Feng; Li, Yang; Zhang, Sainan; Ren, Xueqin; Hu, Shuwen

2015-06-03

Chlorpyrifos' application and delivery to the target substrate needs to be controlled to improve its use. Herein, poly(butyl acrylate-co-styrene) (poly(BA/St)) and poly(BA/St/ethylene glycol dimethacrylate (EGDMA)) microcapsules loaded with chlorpyrifos as a slow release formulation were prepared by emulsion polymerization. The effects of structural characteristics on the chlorpyrifos microcapsule particle size, entrapment rate (ER), pesticide loading (PL), and release behaviors in ethyl alcohol were investigated. Fourier transform infrared and thermogravimetric analysis confirmed the successful entrapment of chlorpyrifos. The ER and PL varied with the BA/St monomer ratio, chlorpyrifos/monomer core-to-shell ratio, and EGDMA cross-linker content with consequence that suitable PL was estimated to be smaller than 3.09% and the highest ER was observed as 96.74%. The microcapsule particle size (88.36-101.8 nm) remained mostly constant. The extent of sustainable release decreased with increasing content of BA, St, or chlorpyrifos in the oil phase. Specifically, an adequate degree of cross-linking with EGMDA (0.5-2.5%) increased the extent of sustainable release considerably. However, higher levels of cross-linking with EGDMA (5-10%) reduced the extent of sustainable release. Chlorpyrifos release from specific microcapsules (monomer ratio 1:2 with 0.5% EGDMA or 5 g chlopyrifos) tended to be a diffusion-controlled process, while for others, the kinetics probably indicated the initial rupture release.

A new restricted access molecularly imprinted polymer capped with albumin for direct extraction of drugs from biological matrices: the case of chlorpromazine in human plasma.

PubMed

de Oliveira Isac Moraes, Gabriel; da Silva, Larissa Meirelles Rodrigues; dos Santos-Neto, Alvaro José; Florenzano, Fábio Herbst; Figueiredo, Eduardo Costa

2013-09-01

A new restricted access molecularly imprinted polymer coated with bovine serum albumin (RAMIP-BSA) was developed, characterized, and used for direct analysis of chlorpromazine in human plasma samples. The RAMIP-BSA was synthesized using chlorpromazine, methacrylic acid, and ethylene glycol dimethacrylate as template, functional monomer, and cross-linker, respectively. Glycerol dimethacrylate and hydroxy methyl methacrylate were used to promote a hydrophilic surface (high density of hydroxyl groups). Afterward, the polymer was coated with BSA using glutaraldehyde as cross-linker, resulting in a protein chemical shield around it. The material was able to eliminate ca. 99% of protein when a 44-mg mL(-1) BSA aqueous solution was passed through it. The RAMIP-BSA was packed in a column and used for direct analysis of chlorpromazine in human plasma samples in an online column switching high-performance liquid chromatography system. The analytical calibration curve was prepared in a pool of human plasma samples with chlorpromazine concentrations ranging from 30 to 350 μg L(-1). The correlation coefficient obtained was 0.995 and the limit of quantification was 30 μg L(-1). Intra-day and inter-day precision and accuracy presented variation coefficients and relative errors lower than 15% and within -15 and 15%, respectively. The sample throughput was 3 h(-1) (sample preparation and chromatographic analysis steps) and the same RAMIP-BSA column was efficiently used for about 90 cycles.

Synthesis and characterization of PEG-P(MAA-SS-VCL) nanoparticles

NASA Astrophysics Data System (ADS)

Yu, L. L.; Yang, K.; Mu, R. H.; Zhang, N.; Su, L.

2016-07-01

The PEG-P(MAA-SS-VCL) nanoparticles were obtained using disulfide containing dimethacrylate (SS) as cross-linking agent, using polyethylene glycol methyl acrylate (PEGMA), N-Vinyl-ε-caprolactam (VCL), and methacrylic acid (MAA) as monomers via homogeneous polymerization in aqueous. The PEG-P(MAA-SS-VCL) nanoparticles were characterized by FT-IR and TGA. The particle size and morphology variation in different environments were detected by dynamic light scattering (DLS) and scanning electron microscopy (SEM). It is the very method that PEG-P(MAA-SS-VCL) nanoparticles can be obtained in this study.

Characterization of porous glass fiber-reinforced composite (FRC) implant structures: porosity and mechanical properties.

PubMed

Ylä-Soininmäki, Anne; Moritz, Niko; Lassila, Lippo V J; Peltola, Matti; Aro, Hannu T; Vallittu, Pekka K

2013-12-01

The aim of this study was to characterize the microstructure and mechanical properties of porous fiber-reinforced composites (FRC). Implants made of the FRC structures are intended for cranial applications. The FRC specimens were prepared by impregnating E-glass fiber sheet with non-resorbable bifunctional bis-phenyl glycidyl dimethacrylate and triethylene glycol dimethacrylate resin matrix. Four groups of porous FRC specimens were prepared with a different amount of resin matrix. Control group contained specimens of fibers, which were bound together with sizing only. Microstructure of the specimens was analyzed using a micro computed tomography (micro-CT) based method. Mechanical properties of the specimens were measured with a tensile test. The amount of resin matrix in the specimens had an effect on the microstructure. Total porosity was 59.5 % (median) in the group with the lowest resin content and 11.2 % (median) in the group with the highest resin content. In control group, total porosity was 94.2 % (median). Correlations with resin content were obtained for all micro-CT based parameters except TbPf. The tensile strength of the composites was 21.3 MPa (median) in the group with the highest resin content and 43.4 MPa (median) in the group with the highest resin content. The tensile strength in control group was 18.9 MPa (median). There were strong correlations between the tensile strength of the specimens and most of the micro-CT based parameters. This experiment suggests that porous FRC structures may have the potential for use in implants for cranial bone reconstructions, provided further relevant in vitro and in vivo tests are performed.

Photocatalysis applications of some hybrid polymeric composites incorporating TiO2 nanoparticles and their combinations with SiO2/Fe2O3

PubMed Central

Buruiana, Tinca; Melinte, Violeta; Buruiana, Emil C

2017-01-01

Polymer nanocomposites containing titanium oxide nanoparticles (TiO2 NPs) combined with other inorganic components (Si–O–Si or/and γ-Fe2O3) were prepared by the dispersion of premade NPs (nanocrystalline TiO2, TiO2/SiO2, TiO2/Fe2O3, TiO2/SiO2/Fe2O3) within a photopolymerizable urethane dimethacrylate (polytetrahydrofuran-urethane dimethacrylate, PTHF-UDMA). The physicochemical characterization of nanoparticles and hybrid polymeric composites with 10 wt % NPs (S1–S4) was realized through XRD, TEM and FTIR analyses. The mean size (10–30 nm) and the crystallinity of the NPs varied as a function of the inorganic constituent. The catalytic activity of these hybrid films was tested for the photodegradation of phenol, hydroquinone and dopamine in aqueous solution under UV or visible-light irradiation. The best results were obtained for the films with TiO2/Fe2O3 or TiO2/SiO2/Fe2O3 NPs. The degradation of the mentioned model pollutants varied between 71% and 100% (after 250 min of irradiation) depending on the composition of the hybrid film tested and the light applied (UV–visible light). Also, it was established that such hybrid films can be reused at least for five cycles, without losing too much of the photocatalytic efficiency (ca. 7%). These findings could have implications in the development of new nanocatalysts. PMID:28243566

Self-initiation of UV photopolymerization reactions using tetrahalogenated bisphenol A (meth)acrylates.

PubMed

Pelras, Théophile; Knolle, Wolfgang; Naumov, Sergej; Heymann, Katja; Daikos, Olesya; Scherzer, Tom

2017-05-17

The potential of tetrachlorinated and tetrabrominated bisphenol A diacrylates and dimethacrylates for self-initiation of a radical photopolymerization was investigated. The kinetics of the photopolymerization of an acrylic model varnish containing halogenated monomers was studied by real-time FTIR spectroscopy, whereas the formation of reactive species and secondary products was elucidated by laser flash photolysis and product analysis by GC-MS after steady-state photolysis. The interpretation of the experimental data and the analysis of possible reaction pathways were assisted by quantum chemical calculations. It was shown that all halogenated monomers lead to a significant acceleration of the photopolymerization kinetics at a minimum concentration of 5 wt%. Steady-state and laser flash photolysis measurements as well as quantum chemical calculations showed that brominated and chlorinated samples do not follow the same pathway to generate radical species. Whereas chlorinated (meth)acrylates may cleave only at the C-O bonds of the carboxyl groups resulting in acrolein and oxyl radicals for initiation, brominated monomers may cleave either at the C-O bonds or at the C-Br bonds delivering aryl and bromine radicals. The quantum yields for the photolysis of the halogenated monomers were found to be in the order of 0.1 for acrylates and 0.2 for methacrylates (with an estimated error of 25%), independently of the attached Br and Cl halogens. Finally, the trihalogenated bisphenol A di(meth)acrylate radicals and the acrolein radicals were found to show the highest efficiencies for the reaction with another acrylic double bond leading to the formation of a polymer network.

Bisphenol A and Related Compounds in Dental Materials

PubMed Central

Fleisch, Abby F.; Sheffield, Perry E.; Chinn, Courtney; Edelstein, Burton L.; Landrigan, Philip J.

2014-01-01

CONTEXT Dental sealants and composite filling materials containing bisphenol A (BPA) derivatives are increasingly used in childhood dentistry. Evidence is accumulating that BPA and some BPA derivatives can pose health risks attributable to their endocrine-disrupting, estrogenic properties. OBJECTIVES To systematically compile and critically evaluate the literature characterizing BPA content of dental materials; to assess BPA exposures from dental materials and potential health risks; and to develop evidence-based guidance for reducing BPA exposures while promoting oral health. METHODS The extant toxicological literature and material safety data sheets were used as data sources. RESULTS BPA is released from dental resins through salivary enzymatic hydrolysis of BPA derivatives, and BPA is detectable in saliva for up to 3 hours after resin placement. The quantity and duration of systemic BPA absorption is not clear from the available data. Dental products containing the bisphenol A derivative glycidyl dimethacrylate (bis-GMA) are less likely to be hydrolyzed to BPA and have less estrogenicity than those containing bisphenol A dimethacrylate (bis-DMA). Most other BPA derivatives used in dental materials have not been evaluated for estrogenicity. BPA exposure can be reduced by cleaning and rinsing surfaces of sealants and composites immediately after placement. CONCLUSIONS On the basis of the proven benefits of resin-based dental materials and the brevity of BPA exposure, we recommend continued use with strict adherence to precautionary application techniques. Use of these materials should be minimized during pregnancy whenever possible. Manufacturers should be required to report complete information on the chemical composition of dental products and encouraged to develop materials with less estrogenic potential. PMID:20819896

Adsorption induced enzyme denaturation: the role of polymer hydrophobicity in adsorption and denaturation of alpha-chymotrypsin on allyl glycidyl ether (AGE)-ethylene glycol dimethacrylate (EGDM) copolymers.

PubMed

Lahari, Challa; Jasti, Lakshmi S; Fadnavis, Nitin W; Sontakke, Kalpana; Ingavle, Ganesh; Deokar, Sarika; Ponrathnam, Surendra

2010-01-19

Effects of changes in hydrophobicity of polymeric support on structure and activity of alpha-chymotrypsin (E.C. 3.4.21.1) have been studied with copolymers of allyl glycidyl ether (AGE) and ethylene glycol dimethacrylate (EGDM) with increasing molar ratio of EGDM to AGE (cross-link density 0.05 to 1.5). The enzyme is readily adsorbed from aqueous buffer at room temperature following Langmuir adsorption isotherms in unexpectedly large amounts (25% w/w). Relative hydrophobicity of the copolymers has been assessed by studying adsorption of naphthalene and Fmoc-methionine by the series of copolymers from aqueous solutions. Polymer hydrophobicity appears to increase linearly on increasing cross-link density from 0.05 to 0.25. Further increase in cross-link density causes a decrease in naphthalene binding but has little effect on binding of Fmoc-Met. Binding of alpha-chymotrypsin to these copolymers follow the trend for Fmoc-methionine binding, rather than naphthalene binding, indicating involvement of polar interactions along with hydrophobic interactions during binding of protein to the polymer. The adsorbed enzyme undergoes extensive denaturation (ca. 80%) with loss of both tertiary and secondary structure on contact with the copolymers as revealed by fluorescence, CD and Raman spectra of the adsorbed protein. Comparison of enzyme adsorption behavior with Eupergit C, macroporous Amberlite XAD-2, and XAD-7 suggests that polar interactions of the EGDM ester functional groups with the protein play a significant role in enzyme denaturation.

Synergistic effect of the combination of triethylene-glycol modified Fe3O4 nanoparticles and ultrasound wave on MCF-7 cells

NASA Astrophysics Data System (ADS)

Ebrahimi Fard, Ali; Zarepour, Atefeh; Zarrabi, Ali; Shanei, Ahmad; Salehi, Hossein

2015-11-01

Cancer is a group of disease characterized by uncontrolled growth and spread of abnormal cells in the body. The clinical treatments for cancer include surgery, chemotherapy and radiotherapy. Currently, employing new approaches for treatment has attracted more attentions. One of these approaches is sonodynamic therapy, which is an analogous approach based on the synergistic effect of ultrasound and a chemical component referred to as sonosensitizer. Recent years applications of nanotechnology have witnessed a tremendous expansion of research in medicine especially in treatment of cancers. The combination of sonodynamic therapy and nanotechnology can introduce a new way for cancer therapy. In this study, we used therapeutic ultrasonic waves with intensity of 1 MHz and different concentrations of Fe3O4 nanoparticles, as sonosensitizer, to investigate their combination effect on MCF-7 cell line. Briefly, we divided cells into four different groups; control, cells which got in touch with nanoparticles, cells that with exposure to ultrasound waves and cells which were influenced with combination of nanoparticles and ultrasonic waves. Finally, cell viability assay was used for detection of cytotoxicity effects. Experimental results revealed a significant decrease in viability of cells, which were affected by the combined action of ultrasound field and Fe3O4 nanoparticles, compared to the separate exposure of Fe3O4 nanoparticles or ultrasonic field. The synergic effect of ultrasound waves and Fe ions might be due to the production of toxic free radicals.

Synthesis, characterization, shrinkage and curing kinetics of a new low-shrinkage urethane dimethacrylate monomer for dental applications.

PubMed

Atai, Mohammad; Ahmadi, Mehdi; Babanzadeh, Samal; Watts, David C

2007-08-01

The aim of the study was to synthesize and characterize an isophorone-based urethane dimethacrylate (IP-UDMA) resin-monomer and to investigate its shrinkage and curing kinetics. The IP-UDMA monomer was synthesized through the reaction of polyethylene glycol 400 and isophorone diisocyanate followed by reacting with HEMA to terminate it with methacrylate end groups. The reaction was followed using a standard back titration method and FTIR spectroscopy. The final product was purified and characterized using FTIR, (1)H NMR, elemental analysis and refractive index measurement. The shrinkage-strain of the specimens photopolymerized at circa 700mW/cm(2) was measured using the bonded-disk technique at 23, 35, and 45 degrees C. Initial shrinkage-strain-rates were obtained by numerical differentiation of shrinkage-strain data with respect to time. Degree-of-conversion of the specimens was measured using FTIR spectroscopy. The thermal curing kinetics of the monomer were also studied by differential scanning calorimetry (DSC). The characterization methods confirmed the suggested reaction route and the synthesized monomer. A low shrinkage-strain of about 4% was obtained for the new monomer. The results showed that the shrinkage-strain-rate of the monomer followed the autocatalytic model of Kamal and Sourour [Kamal MR, Sourour S. Kinetic and thermal characterization of thermoset cure. Polym Eng Sci 1973;13(1):59-64], which is used to describe the reaction kinetics of thermoset resins. The model parameters were calculated by linearization of the equation. The model prediction was in a good agreement with the experimental data. The properties of the new monomer compare favorably with properties of the commercially available resins.

Novel rechargeable calcium phosphate nanoparticle-containing orthodontic cement.

PubMed

Xie, Xian-Ju; Xing, Dan; Wang, Lin; Zhou, Han; Weir, Michael D; Bai, Yu-Xing; Xu, Hockin Hk

2017-03-01

White spot lesions (WSLs), due to enamel demineralization, occur frequently in orthodontic treatment. We recently developed a novel rechargeable dental composite containing nanoparticles of amorphous calcium phosphate (NACP) with long-term calcium (Ca) and phosphate (P) ion release and caries-inhibiting capability. The objectives of this study were to develop the first NACP-rechargeable orthodontic cement and investigate the effects of recharge duration and frequency on the efficacy of ion re-release. The rechargeable cement consisted of pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA). NACP was mixed into the resin at 40% by mass. Specimens were tested for orthodontic bracket shear bond strength (SBS) to enamel, Ca and P ion initial release, recharge and re-release. The new orthodontic cement exhibited an SBS similar to commercial orthodontic cement without CaP release (P>0.1). Specimens after one recharge treatment (e.g., 1 min immersion in recharge solution repeating three times in one day, referred to as "1 min 3 times") exhibited a substantial and continuous re-release of Ca and P ions for 14 days without further recharge. The ion re-release did not decrease with increasing the number of recharge/re-release cycles (P>0.1). The ion re-release concentrations at 14 days versus various recharge treatments were as follows: 1 min 3 times>3 min 2 times>1 min 2 times>6 min 1 time>3 min 1 time>1 min 1 time. In conclusion, although previous studies have shown that NACP nanocomposite remineralized tooth lesions and inhibited caries, the present study developed the first orthodontic cement with Ca and P ion recharge and long-term release capability. This NACP-rechargeable orthodontic cement is a promising therapy to inhibit enamel demineralization and WSLs around orthodontic brackets.

Color stability of silorane-based composites submitted to accelerated artificial ageing--an in situ study.

PubMed

Pires-de-Souza, Fernanda de Carvalho Panzeri; Garcia, Lucas da Fonseca Roberti; Roselino, Lourenço de Moraes Rego; Naves, Lucas Zago

2011-07-01

To assess the in situ color stability, surface and the tooth/restoration interface degradation of a silorane-based composite (P90, 3M ESPE) after accelerated artificial ageing (AAA), in comparison with other dimethacrylate monomer-based composites (Z250/Z350, 3M ESPE and Esthet-X, Dentsply). Class V cavities (25 mm(2) × 2 mm deep) were prepared in 48 bovine incisors, which were randomly allocated into 4 groups of 12 specimens each, according to the type of restorative material used. After polishing, 10 specimens were submitted to initial color readings (Easyshade, Vita) and 2 to analysis by scanning electronic microscopy (SEM). Afterwards, the teeth were submitted to AAA for 384 h, which corresponds to 1 year of clinical use, after which new color readings and microscopic images were obtained. The values obtained for the color analysis were submitted to statistical analysis (1-way ANOVA, Tukey, p<0.05). With regard to color stability, it was verified that all the composites showed color alteration above the clinically acceptable levels (ΔE ≥ 3.3), and that the silorane-based composite showed higher ΔE (18.6), with a statistically significant difference in comparison with the other composites (p<0.05). The SEM images showed small alterations for the dimethacrylate-based composites after AAA and extensive degradation for the silorane-based composite with a rupture at the interface between the matrix/particle. It may be concluded that the silorane-based composite underwent greater alteration with regard to color stability and greater surface and tooth/restoration interface degradation after AAA. Copyright © 2011 Elsevier Ltd. All rights reserved.

Tetracalcium phosphate composite containing quaternary ammonium dimethacrylate with antibacterial properties

PubMed Central

Cheng, Lei; Weir, Michael D.; Limkangwalmongkol, Penwadee; Hack, Gary D.; Xu, Hockin H. K.; Chen, Qianming; Zhou, Xuedong

2012-01-01

Tooth caries is a carbohydrate-modified bacterial infectious disease, and recurrent caries is a frequent reason for restoration failure. The objective of this study was to develop a novel antibacterial composite using tetracalcium phosphate (TTCP) fillers and bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide, which is a quaternary ammonium dimethacrylate (QADM). QADM was synthesized using 2-(N,N-dimethylamino)ethyl methacrylate and 2-bromoethyl methacrylate and incorporated into a resin. The resin was filled with 40% TTCP and 30% glass particles. The following QADM mass fractions in the composite were tested: 0%, 6%, 12%, and 18%. Streptococcus mutans biofilms were formed on the composites and the colony-forming units (CFUs), metabolic activity, and lactic acid production were measured. The TTCP-QADM composite had flexural strength and elastic modulus similar to those of two commercial composites (p > 0.1). Increasing the QADM content in TTCP composite greatly decreased the bacteria growth and biofilm matrix production. There were significantly more dead bacteria with increasing QADM content. TTCP composite containing 18% QADM had biofilm CFU, metabolic activity, and acid production about half of those without QADM. Inversely linear relationships were established between QADM mass fraction and S. mutans biofilm CFU, metabolic activity, and acid production, with correlation coefficients R2 ≥ 0.98. In conclusion, TTCP-QADM composites were developed and the effect of QADM mass fraction on the antibacterial properties of the composite was determined for the first time. The novel TTCP-QADM composites possessing a strong antibacterial capability, together with calcium phosphate ion release and good mechanical properties, are promising for dental restorations to reduce biofilm growth and recurrent caries. PMID:22190356

Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites †

PubMed Central

O’Donnell, Justin N.R.; Schumacher, Gary E.; Antonucci, Joseph M.; Skrtic, Drago

2009-01-01

Our studies of amorphous calcium phosphate (ACP)-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/re-mineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC) and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and, ultimately, the suitability of the composites for clinical evaluation. PMID:21966588

Determination of homologous distributions of bisEMA dimethacrylates in bulk-fill resin-composites by GC-MS.

PubMed

Durner, Jürgen; Schrickel, Klaus; Watts, David C; Ilie, Nicoleta

2015-04-01

Ethoxylated bisphenol A dimethacrylate (bisEMA) is a basis monomer in several dental resin composites. It was the aim of the present study to develop a method allowing detection of bisEMA and its different degrees of ethoxylation eluted from polymerized resin composites. High-temperature gas chromatography/mass spectrometry (HT-GC/MS) by direct on-column injection was used to identify ethoxylated bisEMA in ethanol/water (3:1) eluates from polymerized specimen of four bulk-fill resin composites - Venus(®) bulk fill, Surefil(®) SDR™ flow, Filtek™ Bulk Fill and Sonic Fill™. Additionally, the unpolymerised pastes were analysed. The developed method allowed identification of a homologous series of bisEMA up to twelve ethoxy groups in the unpolymerised materials. The molecular masses of the homologous bisEMA varied between 452 g/mol and 892 g/mol and were detected for retention times from 9.43 min to 13.36 min. Analysis of eluates from polymerised materials identified bisEMA monomers with less than 6 ethoxy groups. Chromatograms showed larger peak areas for the lower volatile bisEMA with 4-6 ethoxy groups compared with higher volatile bisEMA with 2 or 3 ethoxy groups, thus indicating that the amounts of these homologues in the pastes were higher. Ethoxylated bisEMA with up to twelve ethoxy groups can be identified by HT-GC/MS. In all eluates bisEMA was found. The higher the number of ethoxy groups the lower are the peak areas from bisEMA in the gas chromatogram. These findings may be significant for toxicological analysis of resin-composites incorporating bis-EMA. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

[Physical properties of resins for veneer crown. (Part 1) Bending strength of thermosetting methacrylic resins (author's transl)].

PubMed

Kashiwada, T

1979-01-01

The physical properties of thermosetting methacrylic resins contain a kind or more than two kinds of cross linking agents were investigated. Knoop hardness and bending strength after drying, water sorption and thermal cycling were listed in table 4 and 5. Hydrophilic resins absorbed water about 3 times as much as hydrophobic resins. The materials contain a small amount of hydrophobic cross linking agents in MMA indicate comparatively excellent properties after drying, water sorption and thermal cycling. Knoop hardness of resins generally reduced by water sorption, especially in the case of the resin contains a large amount of triethylene glycol dimethacrylate.

Mannosylated biodegradable polyethyleneimine for targeted DNA delivery to dendritic cells

PubMed Central

Sun, Xun; Chen, Simu; Han, Jianfeng; Zhang, Zhirong

2012-01-01

Background To establish a potential gene-delivery system with the ability to deliver plasmid DNA to dendritic cells (DCs) more efficiently and specifically, we designed and synthesized a low-molecular-weight polyethyleneimine and triethyleneglycol polymer (PEI–TEG) and a series of its mannosylated derivatives. Methods PEI–TEG was synthesized from PEI2000 and PEI600 with TEG as the cross-linker. PEI–TEG was then linked to mannose via a phenylisothiocyanate bridge to obtain man-PEI–TEG conjugates. The DNA conveyance abilities of PEI–TEG, man-PEI–TEG, as well as control PEI25k were evaluated by measuring their zeta potential, particle size, and DNA-binding abilities. The in vitro cytotoxicity, cell uptake, and transfection efficiency of these PEI/DNA complexes were examined on the DC2.4 cell line. Finally, a maturation experiment evaluated the effect of costimulatory molecules CD40, CD80, and CD86 on murine bone marrow-derived DCs (BMDCs) using flow cytometry. Results PEI–TEG and man-PEI–TEG were successfully synthesized and were shown to retain the excellent properties of PEI25k for condensing DNA. Compared with PEI–TEG as well as PEI25k, the man-PEI–TEG had less cytotoxicity and performed better in both cellular uptake and transfection assays in vitro. The results of the maturation experiment showed that all the PEI/DNA complexes induced an adequate upregulation of surface markers for DC maturation. Conclusion These results demonstrated that man-PEI–TEG can be employed as a DC-targeting gene-delivery system. PMID:22745554

Optimization of monolithic columns for microfluidic devices

NASA Astrophysics Data System (ADS)

Pagaduan, Jayson V.; Yang, Weichun; Woolley, Adam T.

2011-06-01

Monolithic columns offer advantages as solid-phase extractors because they offer high surface area that can be tailored to a specific function, fast mass transport, and ease of fabrication. Porous glycidyl methacrylate-ethylene glycol dimethacrylate monoliths were polymerized in-situ in microfluidic devices, without pre-treatment of the poly(methyl methacrylate) channel surface. Cyclohexanol, 1-dodecanol and Tween 20 were used to control the pore size of the monoliths. The epoxy groups on the monolith surface can be utilized to immobilize target-specific probes such as antibodies, aptamers, or DNA for biomarker detection. Microfluidic devices integrated with solid-phase extractors should be useful for point-of-care diagnostics in detecting specific biomarkers from complex biological fluids.

Sensitization of ultra-long-range excited-state electron transfer by energy transfer in a polymerized film

PubMed Central

Ito, Akitaka; Stewart, David J.; Fang, Zhen; Brennaman, M. Kyle; Meyer, Thomas J.

2012-01-01

Distance-dependent energy transfer occurs from the Metal-to-Ligand Charge Transfer (MLCT) excited state to an anthracene-acrylate derivative (Acr-An) incorporated into the polymer network of a semirigid poly(ethyleneglycol)dimethacrylate monolith. Following excitation, to Acr-An triplet energy transfer occurs followed by long-range, Acr-3An—Acr-An → Acr-An—Acr-3An, energy migration. With methyl viologen dication (MV2+) added as a trap, Acr-3An + MV2+ → Acr-An+ + MV+ electron transfer results in sensitized electron transfer quenching over a distance of approximately 90 Å. PMID:22949698

Novel rechargeable calcium phosphate nanocomposite with antibacterial activity to suppress biofilm acids and dental caries.

PubMed

Al-Dulaijan, Yousif A; Cheng, Lei; Weir, Michael D; Melo, Mary Anne S; Liu, Huaibing; Oates, Thomas W; Wang, Lin; Xu, Hockin H K

2018-05-01

Rechargeable calcium phosphate (CaP) composites were developed recently. However, none of the rechargeable CaP composites was antibacterial. The objectives of this study were to develop the first rechargeable CaP composite that was antibacterial, and to investigate the effects of adding dimethylaminohexadecyl methacrylate (DMAHDM) into rechargeable CaP composite on ion rechargeability and re-release as well as biofilm properties. DMAHDM was synthesized via a Menschutkin reaction. Nanoparticles of amorphous calcium phosphate (NACP) were synthesized using a spray-drying technique. The resin contained ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). Two composites were fabricated: rechargeable NACP composite, and rechargeable NACP-DMAHDM composite. Mechanical properties and ion release and recharge were measured. A dental plaque microcosm biofilm model using saliva was tested. Flexural strength and elastic modulus of rechargeable NACP and NACP-DMAHDM composites matched commercial control composite (p > 0.1). NACP-DMAHDM inhibited biofilm metabolic activity and lactic acid, and reduced biofilm colony-forming units (CFU) by 3-4 log. NACP and NACP-DMAHDM showed similar Ca and P ion recharge and re-release (p > 0.1). Therefore, adding DMAHDM did not compromise the ion rechargeability. One recharge yielded continuous release for 42 d. The release was maintained at the same level with increasing number of recharge cycles, indicating long-term ion release and remineralization capability. The first CaP rechargeable and antibacterial composite was developed. Adding DMAHDM into the rechargeable NACP composite did not adversely affect the Ca and P ion release and recharge, and the composite had much less biofilm growth and lactic acid production, with CFU reduction by 3-4 log. This novel CaP rechargeable composite with long-term remineralization and antibacterial properties is promising for tooth restorations to inhibit caries. Copyright © 2018 Elsevier Ltd. All rights reserved.

Chemical interaction of glycero-phosphate dimethacrylate (GPDM) with hydroxyapatite and dentin.

PubMed

Yoshihara, Kumiko; Nagaoka, Noriyuki; Hayakawa, Satoshi; Okihara, Takumi; Yoshida, Yasuhiro; Van Meerbeek, Bart

2018-04-28

Although the functional monomer glycero-phosphate dimethacrylate (GPDM) has since long been used in several dental adhesives and more recently in self-adhesive composite cements and restoratives, its mechanism of chemical adhesion to hydroxyapatite (HAp) is still unknown. We therefore investigated the chemical interaction of GPDM with HAp using diverse chemical analyzers and ultra-structurally characterized the interface of a GPDM-based primer formulation with dentin. HAp particles were added to a GPDM solution for various periods, upon which they were thoroughly washed with ethanol and water prior to being air-dried. As control, 10-methacryloyloxydecyl dihydrogen phosphate (MDP) was used. The molecular interaction of GPDM with HAp was analyzed using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (NMR) spectroscopy. Crystal formation upon application of GPDM onto dentin was analyzed using thin-film XRD (TF-XRD). Its hydrophobicity was measured using contact-angle measurement. The interaction of GPDM with dentin was characterized using transmission electron microscopy (TEM). XRD revealed the deposition of dicalcium phosphate dihydrate (DCPD: CaHPO 4 ·2H 2 O) on HAp after 24h. NMR confirmed the adsorption of GPDM onto HAp. However, GPDM was easily removed after washing with water, unlike MDP that remained adhered to HAp. Dentin treated with GPDM appeared more hydrophilic compared to dentin treated with MDP. TEM disclosed exposed collagen in the hybrid layer produced by the GPDM-based primer formulation. Although GPDM adsorbed to HAp, it did not form a stable calcium salt. The bond between GPDM and HAp was weak, unlike the strong bond formed by MDP to HAp. Due to its high hydrophilicity, GPDM might be an adequate monomer for an etch-and-rinse adhesive, but appears less appropriate for a 'mild' self-etch adhesive that besides micro-retention ionically interacts with HAp, or for a self-adhesive restorative material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Repairability of CAD/CAM high-density PMMA- and composite-based polymers.

PubMed

Wiegand, Annette; Stucki, Lukas; Hoffmann, Robin; Attin, Thomas; Stawarczyk, Bogna

2015-11-01

The study aimed to analyse the shear bond strength of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA)- and composite-based polymer materials repaired with a conventional methacrylate-based composite after different surface pretreatments. Each 48 specimens was prepared from six different CAD/CAM polymer materials (Ambarino high-class, artBloc Temp, CAD-Temp, Lava Ultimate, Telio CAD, Everest C-Temp) and a conventional dimethacrylate-based composite (Filtek Supreme XTE, control) and aged by thermal cycling (5000 cycles, 5-55 °C). The surfaces were left untreated or were pretreated by mechanical roughening, aluminium oxide air abrasion or silica coating/silanization (each subgroup n = 12). The surfaces were further conditioned with an etch&rinse adhesive (OptiBond FL) before the repair composite (Filtek Supreme XTE) was adhered to the surface. After further thermal cycling, shear bond strength was tested, and failure modes were assessed. Shear bond strength was statistically analysed by two- and one-way ANOVAs and Weibull statistics, failure mode by chi(2) test (p ≤ 0.05). Shear bond strength was highest for silica coating/silanization > aluminium oxide air abrasion = mechanical roughening > no surface pretreatment. Independently of the repair pretreatment, highest bond strength values were observed in the control group and for the composite-based Everest C-Temp and Ambarino high-class, while PMMA-based materials (artBloc Temp, CAD-Temp and Telio CAD) presented significantly lowest values. For all materials, repair without any surface pretreatment resulted in adhesive failures only, which mostly were reduced when surface pretreatment was performed. Repair of CAD/CAM high-density polymers requires surface pretreatment prior to adhesive and composite application. However, four out of six of the tested CAD/CAM materials did not achieve the repair bond strength of a conventional dimethacrylate-based composite. Repair of PMMA- and composite-based polymers can be achieved by surface pretreatment followed by application of an adhesive and a conventional methacrylate-based composite.

Novel rechargeable calcium phosphate nanoparticle-containing orthodontic cement

PubMed Central

Xie, Xian-Ju; Xing, Dan; Wang, Lin; Zhou, Han; Weir, Michael D; Bai, Yu-Xing; Xu, Hockin HK

2017-01-01

White spot lesions (WSLs), due to enamel demineralization, occur frequently in orthodontic treatment. We recently developed a novel rechargeable dental composite containing nanoparticles of amorphous calcium phosphate (NACP) with long-term calcium (Ca) and phosphate (P) ion release and caries-inhibiting capability. The objectives of this study were to develop the first NACP-rechargeable orthodontic cement and investigate the effects of recharge duration and frequency on the efficacy of ion re-release. The rechargeable cement consisted of pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA). NACP was mixed into the resin at 40% by mass. Specimens were tested for orthodontic bracket shear bond strength (SBS) to enamel, Ca and P ion initial release, recharge and re-release. The new orthodontic cement exhibited an SBS similar to commercial orthodontic cement without CaP release (P>0.1). Specimens after one recharge treatment (e.g., 1 min immersion in recharge solution repeating three times in one day, referred to as “1 min 3 times”) exhibited a substantial and continuous re-release of Ca and P ions for 14 days without further recharge. The ion re-release did not decrease with increasing the number of recharge/re-release cycles (P>0.1). The ion re-release concentrations at 14 days versus various recharge treatments were as follows: 1 min 3 times>3 min 2 times>1 min 2 times>6 min 1 time>3 min 1 time>1 min 1 time. In conclusion, although previous studies have shown that NACP nanocomposite remineralized tooth lesions and inhibited caries, the present study developed the first orthodontic cement with Ca and P ion recharge and long-term release capability. This NACP-rechargeable orthodontic cement is a promising therapy to inhibit enamel demineralization and WSLs around orthodontic brackets. PMID:27811847

Cytotoxicity and induction of DNA double-strand breaks by components leached from dental composites in primary human gingival fibroblasts.

PubMed

Shehata, Mohamed; Durner, Jürgen; Eldenez, Ayce; Van Landuyt, Kirsten; Styllou, Panorea; Rothmund, Lena; Hickel, Reinhard; Scherthan, Harry; Geurtsen, Werner; Kaina, Bernd; Carell, Thomas; Reichl, Franz X

2013-09-01

The public interest steadily increases in the biological adverse effects caused by components released from resin-based dental restorations. In this study, the cytotoxicity and the genotoxicity were investigated of following released components from dental resin restorations in human gingival fibroblasts (HGF): tetraethyleneglycol dimethacrylate (TEEGDMA), neopentylglycol dimethacrylate (Neopen), diphenyliodoniumchloride (DPIC), triphenyl-stibane (TPSB) and triphenylphosphane (TPP). XTT based cell viability assay was used for cytotoxicity screening of substances. γ-H2AX assay was used for genotoxicity screening. In the γ-H2AX assay, HGFs were exposed to the substances for 6h. Induced foci represent double DNA strand breaks (DSBs), which can induce ATM-dependent phosphorylation of the histone H2AX. Cell death effects (apoptosis and necrosis), induced by the substances were visually tested by the same investigator using the fluorescent microscope. All tested substances induced a dose-dependent loss of viability in HGFs. Following toxicity ranking among the substances at EC50-concentration were found in the XTT assay (mM, mean±SEM; n=5): DPIC>Neopen>TPSB>TPP>TEEGDMA. DSB-foci per HGF-cell were obtained, when HGFs were exposed to the EC50-concentration of each substance in the following order (mean±SEM; n=3): DPIC>Neopen>TPSB>TPP>TEEGDMA. Multi-foci cells (cells that contain more than 40 foci each) in 80 HGF-cells at EC50-concentration of each substance were found as follow (mean±SEM; n=3): DPIC>Neopen>TPP>TPSB>TEEGDMA. Cell apoptosis contained in each substance at EC50-concentration in the following order (mean±SEM; n=3): DPIC>Neopen>TPSB>TPP >TEEGDMA. Cell necrosis contained in each substance at EC50-concentration in the following order (mean±SEM; n=3): DPIC>Neopen>TPSB>TPP>TEEGDMA. Leached components from dental resin restorations can induce DNA DSBs and cell death effects in HGFs. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Fabrication of zeolitic imidazolate framework-8-methacrylate monolith composite capillary columns for fast gas chromatographic separation of small molecules.

PubMed

Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

2015-08-07

A composite zeolitic imidazolate framework-8 (ZIF-8) with a butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.) was fabricated to enhance the separation efficiency of methacrylate monoliths toward small molecules using conventional low-pressure gas chromatography in comparison with a neat butyl methacrylate-co-ethylene dimethacrylate (BuMA-co-EDMA) monolithic capillary column (33.5cm long×250μm i.d.). The addition of 10mgmL(-1) ZIF-8 micro-particles increased the BET surface area of BuMA-co-EDMA by 3.4-fold. A fast separation of five linear alkanes in 36s with high resolution (Rs≥1.3) was performed using temperature program. Isothermal separation of the same sample also showed a high efficiency (3315platesm(-1) for octane) at 0.89min. Moreover, the column was able to separate skeletal isomers, such as iso-octane/octane and 2-methyl octane/nonane. In addition, an iso-butane/iso-butylene gas mixture was separated at ambient temperature. Comparison with an open tubular TR-5MS column (30m long×250μm i.d.) revealed the superiority of the composite column in separating the five-membered linear alkane mixture with 4-5 times increase in efficiency and a total separation time of 0.89min instead of 4.67min. A paint thinner sample was fully separated using the composite column in 2.43min with a good resolution (Rs≥0.89). The perfect combination between the polymeric monolith, with its high permeability, and ZIF-8, with its high surface area and flexible 0.34nm pore openings, led to the fast separation of small molecules with high efficiency and opened a new horizon in GC applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Endocrine-Disrupting Potential of Bisphenol A, Bisphenol A Dimethacrylate, 4-n-Nonylphenol, and 4-n-Octylphenol in Vitro: New Data and a Brief Review

PubMed Central

Bonefeld-Jørgensen, Eva C.; Long, Manhai; Hofmeister, Marlene V.; Vinggaard, Anne Marie

2007-01-01

Background An array of environmental compounds is known to possess endocrine disruption (ED) potentials. Bisphenol A (BPA) and bisphenol A dimethacrylate (BPA-DM) are monomers used to a high extent in the plastic industry and as dental sealants. Alkylphenols such as 4-n-nonylphenol (nNP) and 4-n-octylphenol (nOP) are widely used as surfactants. Objectives We investigated the effect in vitro of these four compounds on four key cell mechanisms including transactivation of a) the human estrogen receptor (ER), b) the human androgen receptor (AR), c) the aryl hydrocarbon receptor (AhR), and d) aromatase activity. Results All four compounds inhibited aromatase activity and were agonists and antagonists of ER and AR, respectively. nNP increased AhR activity concentration-dependently and further increased the 2,3,7,8-tetrachlorodibenzo-p-dioxin AhR action. nOP caused dual responses with a weak increased and a decreased AhR activity at lower (10−8 M) and higher concentrations (10−5–10−4 M), respectively. AhR activity was inhibited with BPA (10−5–10−4 M) and weakly increased with BPA-DM (10−5 M), respectively. nNP showed the highest relative potency (REP) compared with the respective controls in the ER, AhR, and aromatase assays, whereas similar REP was observed for the four chemicals in the AR assay. Conclusion Our in vitro data clearly indicate that the four industrial compounds have ED potentials and that the effects can be mediated via several cellular pathways, including the two sex steroid hormone receptors (ER and AR), aromatase activity converting testosterone to estrogen, and AhR; AhR is involved in syntheses of steroids and metabolism of steroids and xenobiotic compounds. PMID:18174953

Effect of various visible light photoinitiators on the polymerization and color of light-activated resins.

PubMed

Arikawa, Hiroyuki; Takahashi, Hideo; Kanie, Takahito; Ban, Seiji

2009-07-01

The purpose of this study was to investigate effects of various visible light photoinitiators on the polymerization efficiency and color of the light-activated resins. Four photoinitiators, including camphorquinone, phenylpropanedione, monoacrylphosphine oxide (TPO), and bisacrylphosphine oxide (Ir819), were used. Each photoinitiator was dissolved in a Bis-GMA and TEGDMA monomer mixture. Materials were polymerized using dental quartz-tungsten halogen lamp (QTH), plasma-ark lamp and blue LED light-curing units, and a custom-made violet LED light unit. The degree of monomer conversion and CIE L*a*b* color values of the resins were measured using a FTIR and spectral transmittance meter. The degree of monomer conversions of TPO- and Ir819-containing resins polymerized with the violet-LED unit were higher than camphorquinone-containing resin polymerized with the QTH light-curing unit. The lowest color values were observed for the TPO-containing resin. Our results indicate that the TPO photoinitiator and the violet-LED light unit may provide a useful and improved photopolymerization system for dental light-activated resins.

Molecularly Imprinted Microrods via Mesophase Polymerization.

PubMed

Parisi, Ortensia Ilaria; Scrivano, Luca; Candamano, Sebastiano; Ruffo, Mariarosa; Vattimo, Anna Francesca; Spanedda, Maria Vittoria; Puoci, Francesco

2017-12-28

The aim of the present research work was the synthesis of molecularly imprinted polymers (MIPs) with a rod-like geometry via "mesophase polymerization". The ternary lyotropic system consisting of sodium dodecyl sulfate (SDS), water, and decanol was chosen to prepare a hexagonal mesophase to direct the morphology of the synthesized imprinted polymers using theophylline, methacrylic acid, and ethylene glycol dimethacrylate as a drug model template, a functional monomer, and a crosslinker, respectively. The obtained molecularly imprinted microrods (MIMs) were assessed by performing binding experiments and in vitro release studies, and the obtained results highlighted good selective recognition abilities and sustained release properties. In conclusion, the adopted synthetic strategy involving a lyotropic mesophase system allows for the preparation of effective MIPs characterized by a rod-like morphology.

The biocompatability of mesoporous inorganic-organic hybrid resin films with ionic and hydrophilic characteristics.

PubMed

Kim, Gahee; Hong, Lan Young; Jung, Jungwoon; Kim, Dong-Pyo; Kim, Heesoo; Kim, Ik Jung; Kim, Jung Ran; Ree, Moonhor

2010-03-01

New mesoporous silicate-titania resin systems hybridized with 4,5-dihydroxy-m-benzenedisulfonic acid and poly(ethylene glycol)-dimethacrylate component were developed. These inorganic-organic hybrid resins were found to reveal highly controlled ionic and hydrophilic surface with excellent durability and adhesion onto various substrates. The resin films revealed high resistance to nonspecific adsorption of fibrinogen and to adherence by several bacterial pathogens such as Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis. Furthermore, excellent biocompatibility of the developed resins was proved by both HEp-2 cell adhesion in vitro and subcutaneous implantation in mice. The inorganic-organic hybrid resins are strongly promising for biomedical applications including biomedical devices and biosensors. Copyright 2009 Elsevier Ltd. All rights reserved.

Ionic liquids in a poly ethylene oxide cross-linked gel polymer as an electrolyte for electrical double layer capacitor

NASA Astrophysics Data System (ADS)

Chaudoy, V.; Tran Van, F.; Deschamps, M.; Ghamouss, F.

2017-02-01

In the present work, we developed a gel polymer electrolyte via the incorporation of a room temperature ionic liquid into a cross-linked polymer matrix. The cross-linked gel electrolyte was prepared using a free radical polymerization of methacrylate and dimethacrylate oligomers dissolved in 1-propyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide. Combining the advantages of the ionic liquids and of conventional polymers, the cross-linked gel polymer electrolyte was used both as a separator and as an electrolyte for a leakage-free and non-flammable EDLC supercapacitor. The quasi-all solid-state supercapacitors showed rather good capacitance, power and energy densities by comparison to a liquid electrolyte-based EDLC.

Reactive carriers of immobilized compounds.

PubMed

Coupek, J; Labský, J; Kálal, J; Turková, J; Valentová, O

1977-04-12

Sphericanl macroporous reactive carriers capable of forming covalent bonds with amino acids and proteins were prepared by the suspension copolymerization of 2-hydroxyethyl methacrylate, ethylene dimethacrylate and p-nitrophenyl esters of methacrylic acid and methacryloyl derivatives of glycine, beta-alanine and epsilon-aminocaproic acid. The effect of the spacer length, pH and the type of the buffer used, concentration of reactive groups in the copolymer, concentration of the ligand and the participation of the hydrolytic and aminolytic reaction of p-nitrophenyl functional groups in the attachment of glycine, D,L-phenylalanine and serumalbumin was studied. Macroporous copolymers containing reactive functional groups can be used as active enzyme carriers, if their activity is not blocked by the presence of p-nitrophenol split off in the attachment reaction.

[Contact dermatitis from polyacrylate in TENS electrode].

PubMed

Weber-Muller, F; Reichert-Penetrat, S; Schmutz, J-L; Barbaud, A

2004-05-01

Transcutaneous electric nerve stimulation (TENS) is useful for many chronic pains. It induces few serious side effects, but skin reactions are not rare. We report on two cases of contact dermatitis due to TENS electrodes by sensitization to the acrylate in TENS conductive gel. A 50 year-old man suffered from post-traumatic lumbar pair. He developed eczematous lesions on the sites where the TENS electrodes were applied. Patch tests were positive with the TENS gel, with ethylene glycol dimethylacrylate (2 p. 100 petrolatum) and ethyl-acrylate (2 p. 100 petrolatum) on day 2 and 4 readings. A 54 Year-old man had a paralysis of the foot elevator following rupture of an aneurysm. After 2 months, he had an eczema on the sites where the TENS electrodes were applied. Patch tests were negative with the TENS electrodes but positive with 2-hydroxyethyl acrylate (0.1 p. 100 petrolatum), triethyleneglycol diacrylate (0.1 p. 100 petrolatum), 2-hydroxyethyl methacrylate (2 p. 100 petrolatum) and 2-hydroxypropyl methacrylate (2 p. 100 petrolatum) on day 2 and 4 readings. TENS transmits small electrical currents through the skin that induce the depolarization of the affected sensory nerve endings. They have few serious side effects but skin reactions such as irritation, burns or allergy to propylene glycol in the electrode gel, to the rubber of the electrodes (mercaptobenzothiazole) or to the metallic part of the electrodes, i.e. nickel, are not uncommon. To our knowledge, only one case of an allergy to the polyacrylates of TENS electrode gel has been previously reported in the literature. We emphasize that acrylate could be the main sensitizer in the more recently commercialized TENS electrodes and will propose alternative ways of treating patients sensitized to acrylate and who require treatment with TENS.

Synthesis of a Temperature-Sensitive Matrine-Imprinted Polymer and Its Potential Application for the Selective Extraction of Matrine from Radix Sophorae Tonkinensis

PubMed Central

Jiang, Minjie; Wang, Lisheng; Liu, Xu; Yang, Hua; Ren, Fan; Gan, Lizhen; Jiang, Weizhe

2015-01-01

A temperature-sensitive matrine-imprinted polymer was prepared in chloroform by free-radical cross-linking copolymerization of methacrylic acid at 60 °C in the presence of ethylene glycol dimethacrylate as the cross-linker, N-isopropyl acrylamide as the temperature-responsive monomer and matrine as the template molecule. Binding experiments and Scatchard analyses revealed that two classes of binding sites were formed on molecular imprinted polymer (MIP) at 50 °C. Additionally, the thermoresponsive MIP was tested for its application as a sorbent material for the selective separation of matrine from Chinese medicinal plant radix Sophorae tonkinensis. It was shown that the thermoresponsive MIP displayed different efficiency in clean-up and enrichments using the SPE protocol at different temperatures. PMID:25658797

One-pot synthesis of polythiol ligand for highly bright and stable hydrophilic quantum dots toward bioconjugate formation

NASA Astrophysics Data System (ADS)

Dezhurov, Sergey V.; Krylsky, Dmitry V.; Rybakova, Anastasia V.; Ibragimova, Sagila A.; Gladyshev, Pavel P.; Vasiliev, Alexey A.; Morenkov, Oleg S.

2018-03-01

A fast and efficient one-pot synthesis of thiol-terminated poly(vinylpirrolidone-co-maleic anhydride-co-ethylene glycol dimethacrylate) based heterobifunctional polymer (PTVP) has been developed. The polymer was used for the modification of quantum dots (QDs) to prepare water soluble and stable QDs with emission quantum yield as high as 80%. Using carbodiimide method, PTVP-capped red light-emitting QDs were conjugated to model monoclonal antibodies specific to glycoprotein B (gB) of Aujeszky’s disease virus (ADV) and successfully used in the lateral flow assay (LFA) for the detection of ADV gB in biological fluids. A comparative analysis of the sensitivity of the method was carried out using three types of QDs emitting in the red and far-red region.

Preparation of well-defined erythromycin imprinted non-woven fabrics via radiation-induced RAFT-mediated grafting

NASA Astrophysics Data System (ADS)

Söylemez, Meshude Akbulut; Barsbay, Murat; Güven, Olgun

2018-01-01

Radiation-induced RAFT polymerization technique was applied to synthesize well-defined molecularly imprinted polymers (MIPs) of erythromycin (ERY). Methacrylic acid (MAA) was grafted onto porous polyethylene (PE)/polypropylene (PP) nonwoven fabrics, under γ-irradiation by employing 2-pheny-2-propyl benzodithioate as the RAFT agent and ethylene glycol dimethacrylate (EGDMA) as the crosslinker. MAA/erythromycin ratios of 2/1, 4/1, 6/1 were tested to optimize the synthesis of MIPs. The highest binding capacity was encountered at a MAA/ERY ratio of 4/1. Non-imprinted polymers (NIPs) were also synthesized in the absence of ERY. The MIPs synthesized by RAFT method presented a better binding capacity compared to those prepared by conventional method where no RAFT agent was employed.

Synthesis, characterization and evaluation of uniformly sized core-shell imprinted microspheres for the separation trans-resveratrol from giant knotweed

NASA Astrophysics Data System (ADS)

Zhang, Zhaohui; Liu, Li; Li, Hui; Yao, Shouzhuo

2009-09-01

A novel core-shell molecularly imprinting microspheres (MIMs) with trans-resveratrol as the template molecule; acrylamide (AA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker, was prepared based on SiO 2 microspheres with surface imprinting technique. These core-shell trans-resveratrol imprinted microspheres were characterized by infrared spectra (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and high performance liquid chromatography (HPLC). The results showed that these core-shell imprinted microspheres, which take on perfect spherical shape with average shell thickness of 150 nm, exhibit especially selective recognition for trans-resveratrol. These imprinted microspheres were applied as solid-phase extraction materials for selective extraction of trans-resveratrol from giant knotweed extracting solution successfully.

Novel approach for extraction of quercetin using molecular imprinted membranes

NASA Astrophysics Data System (ADS)

Kamarudin, Siti Fatimah; Ahmad, Mohd Noor; Dzahir, Irfan Hatim Mohamed; Nasir, Azalina Mohamed; Ishak, Noorhidayah; Halim, Nurul Farhanah

2017-12-01

Quercetin imprinted membrane (QIM) was synthesized and applied for the extraction of quercetin. The quercetin imprinted membranes (QIM) were fabricated through a non-covalent approach via surface thermal polymerization. Polyvinylidene fluoride (PVDF) microfiltration membrane was used as a support to improve mechanical stability of the membrane. The thin imprinted layer was formed by copolymerization of acrylamide (AA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinker in the presence of quercetin as template in tetrahydrofuran (THF) solution. The Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM) were used to visualize the surface of membrane. Batch rebinding and binding kinetic experiments proved that the binding properties of the QIM are higher than non-imprinted membranes (NIM). QIM also have higher selectivity towards quercetin compared to sinensetin and rosmarinic acid.

Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology.

PubMed

Babarahimi, Vida; Talebpour, Zahra; Haghighi, Farideh; Adib, Nuoshin; Vahidi, Hamed

2018-05-10

In our previous work, a new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The formulation of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate monolithic polymer was optimized and the satisfactory quality of prepared coated stir bar was demonstrated. In this work, the prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of losartan (LOS) and valsartan (VAS) in human plasma samples. In a comparison study, the extraction efficiency of the prepared stir bar was accompanied much higher extraction efficiency than the two commercial stir bars (polydimethylsiloxand and polyacrylate) for both target compounds. In order to improve the desorption efficiency of LOS and VAS, the best values for effective parameters on desorption step were selected systematically. Also, the effective parameters on extraction step were optimized using a Box-Behnken design. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for LOS (24-1000 ng mL -1 ) and VAS (91-1000 ng mL -1 ), with correlation coefficients of 0.9998 and 0.9971 and detection limits of 7 and 27 ng mL -1 , respectively. The intra- and inter-day recovery ranged from 98 to 117%, and the relative standard deviations were less than 8%. Finally, the proposed technique was successfully applied to the analysis of LOS and VAS at their therapeutic levels in volunteer patient plasma sample. The obtained results were confirmed using liquid chromatography-mass spectrometry. The proposed technique was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of LOS and VLS in biological fluids. The obtained results were demonstrated that the lower selectivity of UV in comparison with MS detection was rectified by appropriate sample preparation through proposed extraction method to eliminate as many interfering compounds as possible. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of calcium phosphate nanocomposite on in vitro remineralization of human dentin lesions.

PubMed

Weir, Michael D; Ruan, Jianping; Zhang, Ning; Chow, Laurence C; Zhang, Ke; Chang, Xiaofeng; Bai, Yuxing; Xu, Hockin H K

2017-09-01

Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time. NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). After restoring the dentin lesions with nanocomposites as well as a non-releasing commercial composite control, the specimens were treated with cyclic demineralization (pH 4, 1h per day) and remineralization (pH 7, 23h per day) for 4 or 8 weeks. Calcium (Ca) and phosphate (P) ion releases from composites were measured. Dentin lesion remineralization was measured at 4 and 8 weeks by transverse microradiography (TMR). Lowering the pH increased ion release of NACP and NACP-TTCP composites. At 56 days, the released Ca concentration in mmol/L (mean±SD; n=3) was (13.39±0.72) at pH 4, much higher than (1.19±0.06) at pH 7 (p<0.05). At 56 days, P ion concentration was (5.59±0.28) at pH 4, much higher than (0.26±0.01) at pH 7 (p<0.05). Quantitative microradiography showed typical subsurface dentin lesions prior to the cyclic demineralization/remineralization treatment, and dentin remineralization via NACP and NACP-TTCP composites after 4 and 8 weeks of treatment. At 8 weeks, NACP nanocomposite achieved dentin lesion remineralization (mean±SD; n=15) of (48.2±11.0)%, much higher than (5.0±7.2)% for dentin in commercial composite group after the same cyclic demineralization/remineralization regimen (p<0.05). Novel NACP-based nanocomposites were demonstrated to achieve dentin lesion remineralization for the first time. These results, coupled with acid-neutralization and good mechanical properties shown previously, indicate that the NACP-based nanocomposites are promising for restorations to inhibit caries and protect tooth structures. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Analysis of chemical warfare agents in organic liquid samples with magnetic dispersive solid phase extraction and gas chromatography mass spectrometry for verification of the chemical weapons convention.

PubMed

Singh, Varoon; Purohit, Ajay Kumar; Chinthakindi, Sridhar; Goud, Raghavender D; Tak, Vijay; Pardasani, Deepak; Shrivastava, Anchal Roy; Dubey, Devendra Kumar

2016-05-27

A simple, sensitive and low temperature sample preparation method is developed for detection and identification of Chemical Warfare Agents (CWAs) and scheduled esters in organic liquid using magnetic dispersive solid phase extraction (MDSPE) followed by gas chromatography-mass spectrometry analysis. The method utilizes Iron oxide@Poly(methacrylic acid-co-ethylene glycol dimethacrylate) resin (Fe2O3@Poly(MAA-co-EGDMA)) as sorbent. Variants of these sorbents were prepared by precipitation polymerization of methacrylic acid-co-ethylene glycol dimethacrylate (MAA-co-EGDMA) onto Fe2O3 nanoparticles. Fe2O3@poly(MAA-co-EGDMA) with 20% MAA showed highest recovery of analytes. Extractions were performed with magnetic microspheres by MDSPE. Parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, method showed linearity in the range of 0.1-3.0μgmL(-1) (r(2)=0.9966-0.9987). The repeatability and reproducibility (relative standard deviations (RSDs) %) were in the range of 4.5-7.6% and 3.4-6.2% respectively for organophosphorous esters in dodecane. Limits of detection (S/N=3/1) and limit of quantification (S/N=10/1) were found to be in the range of 0.05-0.1μgmL(-1) and 0.1-0.12μgmL(-1) respectively in SIM mode for selected analytes. The method was successfully validated and applied to the extraction and identification of targeted analytes from three different organic liquids i.e. n-hexane, dodecane and silicon oil. Recoveries ranged from 58.7 to 97.3% and 53.8 to 95.5% at 3μgmL(-1) and 1μgmL(-1) spiking concentrations. Detection of diethyl methylphosphonate (DEMP) and O-Ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX) in samples provided by the Organization for Prohibition of Chemical Weapons Proficiency Test (OPCW-PT) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2016 Elsevier B.V. All rights reserved.

Dental Composite Restorations and Neuropsychological Development in Children: Treatment Level Analysis from a Randomized Clinical Trial

PubMed Central

Maserejian, Nancy N.; Trachtenberg, Felicia L.; Hauser, Russ; McKinlay, Sonja; Shrader, Peter; Bellinger, David C.

2012-01-01

Background Resin-based dental restorations may intra-orally release their components and bisphenol A. Gestational bisphenol A exposure has been associated with poorer executive functioning in children. Objectives To examine whether exposure to resin-based composite restorations is associated with neuropsychological development in children. Methods Secondary analysis of treatment level data from the New England Children’s Amalgam Trial, a 2-group randomized safety trial conducted from 1997–2006. Children (N=534) aged 6–10 y with >2 posterior tooth caries were randomized to treatment with amalgam or resin-based composites (bisphenol-A-diglycidyl-dimethacrylate-composite for permanent teeth; urethane dimethacrylate-based polyacid-modified compomer for primary teeth). Neuropsychological function at 4- and 5-year follow-up (N=444) was measured by a battery of tests of executive function, intelligence, memory, visual-spatial skills, verbal fluency, and problem-solving. Multivariable generalized linear regression models were used to examine the association between composite exposure levels and changes in neuropsychological test scores from baseline to follow-up. For comparison, data on children randomized to amalgam treatment were similarly analyzed. Results With greater exposure to either dental composite material, results were generally consistent in the direction of slightly poorer changes in tests of intelligence, achievement or memory, but there were no statistically significant associations. For the four primary measures of executive function, scores were slightly worse with greater total composite exposure, but statistically significant only for the test of Letter Fluency (10-surface-years β= −0.8, SE=0.4, P=0.035), and the subtest of color naming (β= −1.5, SE=0.5, P=0.004) in the Stroop Color-Word Interference Test. Multivariate analysis of variance confirmed that the negative associations between composite level and executive function were not statistically significant (MANOVA P=0.18). Results for greater amalgam exposure were mostly nonsignificant in the opposite direction of slightly improved scores over follow-up. Conclusions Dental composite restorations had statistically insignificant associations of small magnitude with impairments in neuropsychological test change scores over 4- or 5-years of follow-up in this trial. PMID:22906860

Determination of double bond conversion in dental resins by near infrared spectroscopy.

PubMed

Stansbury, J W; Dickens, S H

2001-01-01

This study determined the validity and practicality of near infrared (NIR) spectroscopic techniques for measurement of conversion in dental resins. Conversion measurements by NIR and mid-IR were compared using two techniques: (1) The conversion of 3mm thick photopolymerized Bis-GMA/TEGDMA resin specimens was determined by transmission NIR. Specimens were then ground and reanalyzed in KBr pellet form by mid-IR. (2) As further verification, thin resin films were photocured and analyzed by mid-IR. Multiple thin films were then compressed into a thick pellet for examination by NIR. Conversion values obtained by NIR and mid-IR techniques did not differ significantly. A correction for changing specimen thickness due to polymerization shrinkage was applied to NIR conversion measurements since an internal standard reference peak was not employed. Sensitivity of the NIR technique was superior to those based on the mid-IR. The nondestructive analysis of conversion in dental resins by NIR offers advantages of convenience, practical specimen dimensions and precision compared with standard mid-IR analytical procedures. Because glass is virtually transparent in the NIR spectrum, this technique has excellent potential for use with filled dental resins as well.

Molecularly Imprinted Polymer Nanoparticles for Formaldehyde Sensing with QCM.

PubMed

Hussain, Munawar; Kotova, Kira; Lieberzeit, Peter A

2016-06-30

Herein, we report on molecularly imprinted polymers (MIPs) for detecting formaldehyde vapors in air streams. A copolymer thin film consisting of styrene, methacrylic acid, and ethylene glycol dimethacrylate on quartz crystal microbalance (QCM) yielded a detection limit of 500 ppb formaldehyde in dry air. Surprisingly, these MIPs showed specific behavior when tested against a range of volatile organic compounds (VOCs), such as acetaldehyde, methanol, formic acid, and dichloromethane. Despite thus being a suitable receptor in principle, the MIPs were not useful for measurements at 50% humidity due to surface saturation by water. This was overcome by introducing primary amino groups into the polymer via allyl amine and by changing the coating morphology from thin film to nanoparticles. This led to the same limit of detection (500 ppb) and selectivity as before, but at the real-life conditions of 50% relative humidity.

The use of poly(methacrylic acid) nanogel to control the release of amoxycillin with lower cytotoxicity.

PubMed

Liu, Tao; Liu, Hongxi; Wu, Zhimin; Chen, Tao; Zhou, Lin; Liang, Yuanyuan; Ke, Bo; Huang, Hongxing; Jiang, Zhenyou; Xie, Mingqiang; Wu, Ting

2014-10-01

In order to control the release of amoxycillin (AM) with lower cytotoxicity and higher activity, ethylene glycol dimethacrylate was used as the cross-linker, and a series of poly(methacrylic acid) (PMAA) nanogels were prepared to load the AM. Then, the morphology, size, in vitro release property, long-term antibacterial performance, cytotoxicity, stability and activity of this novel AM/PMAA nanogel were investigated. The results showed that the AM/PMAA nanogel sustainably released AM with long-term antibacterial activity. Moreover, the AM/PMAA nanogel could improve the stability of AM. More importantly, this AM/PMAA nanogel showed slighter cytotoxicity than AM alone, suggesting that the AM/PMAA nanogel was a more useful dosage form than AM for infectious diseases. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Rechargeable infection-responsive antifungal denture materials.

PubMed

Cao, Z; Sun, X; Yeh, C-K; Sun, Y

2010-12-01

Candida-associated denture stomatitis (CADS) is a significant clinical concern. We developed rechargeable infection-responsive antifungal denture materials for potentially managing the disease. Polymethacrylic acid (PMAA) was covalently bound onto diurethane dimethacrylate denture resins in the curing step. The PMAA resins bound cationic antifungal drugs such as miconazole and chlorhexidine digluconate (CG) through ionic interactions. The anticandidal activities of the drug-containing PMAA-resin discs were sustained for a prolonged period of time (weeks and months). Drug release was much faster at acidic conditions (pH 5) than at pH 7. Drugs bound to the denture materials could be "washed out" by treatment with EDTA, and the drug-depleted resins could be recharged with the same or a different class of anticandidal drugs. These results suggest clinical potential of the newly developed antifungal denture materials in the management of CADS and other infectious conditions.

Mechanical properties of woven glass fiber-reinforced composites.

PubMed

Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

2006-06-01

The aim of this investigation was to measure the flexural and compressive strengths and the corresponding moduli of cylindrical composite specimens reinforced with woven glass fiber. Test specimens were made by light-curing urethane dimethacrylate oligomer with woven glass fiber of 0.18-mm standard thickness. Tests were conducted using four reinforcement methods and two specimen diameters. Flexural strength and modulus of woven glass fiber-reinforced specimens were significantly greater than those without woven glass fiber (p < 0.01). Likewise, compressive strength of reinforced specimens was significantly greater than those without woven glass fiber (p < 0.01), except for specimens reinforced with woven glass fiber oriented at a tilt direction in the texture (p > 0.05). In terms of comparison between the two specimen diameters, no statistically significant differences in flexural strength and compressive strength (p > 0.05) were observed.

Optical, structural and nonlinear optical properties of laser ablation synthesized Ag nanoparticles and photopolymer nanocomposites based on them

NASA Astrophysics Data System (ADS)

Zulina, Natalia A.; Pavlovetc, Ilia M.; Baranov, Mikhail A.; Denisyuk, Igor Yu.

2017-03-01

In this work Ag nanoparticles (NPs) stable colloid solution were prepared by laser ablation of chemically pure silver rod in liquid monomer isodecyl acrylate (IDA). Sizes of obtained nanoparticles were determined by scanning electron microscope and vary from 27 to 120 nm. Nanocomposites films were prepared from obtained stable colloid solution of AgNPs by photocuring. For aliphatic polymer IDA long molecules cross-linking Diurethane dimethacrylate, 1,6-Hexandiol diacrylate and Tetra (ethylene glycol) diacrylate were used. Prepared nanomaterials exhibit strong third-order nonlinear optical responses, which was estimated by using z-scan technique. The third-order nonlinear optical coefficients of the studied nanocomposites were found to be up to Reχ(3)=1.31×10-5 (esu) and Imχ(3)=7.64×10-5 (esu).

Effect of concentration of polyfunctional monomers on physical properties of acrylonitrile butadiene rubber under electron-beam irradiation

NASA Astrophysics Data System (ADS)

Yasin, Tariq; Ahmed, Shamshad; Ahmed, Munir; Yoshii, Fumio

2005-06-01

An investigation has been undertaken to find out the effect of concentration of different polyfunctional monomers (PFMs) on the physical properties of the acrylonitrile-butadiene rubber (NBR) crosslinked by electron beam (EB). The PFMs used were diethylene glycol dimethacrylate, trimethylol propane trimethacrylate and trimethylol propane triacrylate. The physical properties of EB-irradiated NBR sheets were evaluated by measuring the tensile strength, elongation percent at break, hardness and gel fraction. The results showed a remarkable increase in tensile strength, hardness and gel fraction as the concentration of PFMs was increased from 1 part per hundred (phr) to 5 phr in the NBR samples whereas elongation percent decreased in a steady manner. The improvement in physical properties of radiation crosslinked NBR in the presence of PFMs may be attributed to its increased crosslinking density as observed by the corresponding increase in gel content.

Adsorption of β-sitosterol on molecularly imprinted polymer

NASA Astrophysics Data System (ADS)

Soekamto, N. H.; Fauziah, St.; Taba, P.; Amran, M. B.

2017-04-01

Molecularly Imprinted Polymer (MIP) has been synthesized using methacrylate acid (MAA) as a monomer with hydroxyl and carbonyl functional groups that can react with ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent, and β-sitosterol as a template molecule. After the template was removed from the polymer, MIP_TFMAA was obtained. The MIP was used to adsorb β-sitosterol. The amount of β-sitosterol in solution after the adsorption was determined by HPLC. The results showed that the MIP was able to adsorb well the β-sitosterol at a pH 7 and the contact time of 90 min. The kinetic adsorption data obtained for β-sitosterol followed the pseudo-second-order model and consistent with the model of Feundlich isothermal with the adsorption capacity of 1.05 mg/g. The MIP was selective on β-sitosterol because it was able to adsorb β-sitosterol better than cholesterol.

A novel hybrid metal-organic framework-polymeric monolith for solid-phase microextraction.

PubMed

Lin, Chen-Lan; Lirio, Stephen; Chen, Ya-Ting; Lin, Chia-Her; Huang, Hsi-Ya

2014-03-17

This study describes the fabrication of a novel hybrid metal-organic framework- organic polymer (MOF-polymer) for use as a stationary phase in fritless solid-phase microextraction (SPME) for validating analytical methods. The MOF-polymer was prepared by using ethylene dimethacrylate (EDMA), butyl methacrylate (BMA), and an imidazolium-based ionic liquid as porogenic solvent followed by microwave-assisted polymerization with the addition of 25 % MOF. This novel hybrid MOF-polymer was used to extract penicillin (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) under different conditions. Quantitative analysis of the extracted penicillin samples using the MOF-organic polymer for SPME was conducted by using capillary electrochromatography (CEC) coupled with UV analysis. The penicillin recovery was 63-96.2 % with high reproducibility, sensitivity, and reusability. The extraction time with the proposed fabricated SPME was only 34 min. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation, co-assembling and interfacial crosslinking of photocurable and folate-conjugated amphiphilic block copolymers for controlled and targeted drug delivery: smart armored nanocarriers.

PubMed

Khoee, Sepideh; Kavand, Alireza

2014-02-12

Novel pH-sensitive, biodegradable and biocompatible copolymers based on polycaprolactone-poly(ethylene glycol) (PCL/PEG) were synthesized and further modified with folic acid and/or acryloyl chloride. The mixed polymeric micelles were formed by self-assembling of folated-copolymer and non-folated-copolymer with different compositions via nanoprecipitation method. The solubilization of quercetin as anti-cancer drug by the mixed micelle with the optimized composition (folated/non-folated 20/80) was more efficient than those made of each one alone. Nanogels with different crosslinking density were produced in the presence of ethylene glycol dimethacrylate (EGDMA) as the crosslinker via a photochemical method. Interfacial crosslinking of acrylated groups were utilized to produce a core-shell spherical nanoparticle to evaluate their in-vitro drug release and degradation rate. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Rapid removal of aniline from contaminated water by a novel polymeric adsorbent.

PubMed

Huang, Yunhong; Xu, Yang; He, Qinghua; Cao, Yusheng; Du, Bibai

2014-01-01

Dummy molecularly imprinted polymers (DMIPs) for aniline were synthesized by a thermal polymerization method using acrylamide as a functional monomer, ethylene dimethacrylate as a crosslinker, 2,2-azobisisobutyronitrile as a free radical initiator, acetonitrile as a porogenic solvent, and analogues of aniline, namely sulfadiazine, as the template. The DMIPs that were obtained showed a high affinity to aniline compared to non-imprinted polymers. It was proven that the DMIPs obtained using sulfadiazine as the template were much better than the molecularly imprinted polymers using aniline as the template. The results indicated that the Freundlich model was fit for the adsorption model of DMIP for aniline and the adsorption model of the DMIP for aniline was multilayer adsorption. Furthermore, the results showed that the DMIP synthesized by bulk polymerization could be used as a novel adsorbent for removal of aniline from contaminated water.

Rapid CE-UV binding tests of environmentally hazardous compounds with polymer-modified magnetic nanoparticles.

PubMed

Iqbal, Zafar; Alsudir, Samar; Miah, Musharraf; Lai, Edward P C

2011-08-01

Hazardous compounds and bacteria in water have an adverse impact on human health and environmental ecology. Polydopamine (or polypyrrole)-coated magnetic nanoparticles and polymethacrylic acid-co-ethylene glycol dimethacrylate submicron particles were investigated for their fast binding kinetics with bisphenol A, proflavine, naphthalene acetic acid, and Escherichia coli. A new method was developed for the rapid determination of % binding by sequential injection of particles first and compounds (or E. coli) next into a fused-silica capillary for overlap binding during electrophoretic migration. Only nanolitre volumes of compounds and particles were sufficient to complete a rapid binding test. After heterogeneous binding, separation of the compounds from the particles was afforded by capillary electrophoresis. % binding was influenced by applied voltage but not current flow. In-capillary coating of particles affected the % binding of compounds. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Synthesis and Study on Adsorption Property of Congo Red Molecularly Imprinted Polymer Nanospheres].

PubMed

Chang, Zi-qiang; Chen, Fu-bin; Zhang, Yu; Shi, Zuo-long; Yang, Chun-yan; Zhang, Zhu-jun

2015-07-01

Molecularly imprinted polymer nanospheres (MIP) were prepared with Congo red as the template, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross linker, azodiisobutyronitrile (AIBN) as an initiator, and acetonitrile as the porogen by precipitation polymerization. The morphology of MIP was characterized by SEM and TEM which showed that the diameter of MIP was nanometer grade (90 nm) and the shape was homogeneous. The specific surface area and pore volumes of MIP and NIP were examined through Brunauer-Emett-Teller method of nitrogen adsorption experiments. Then, the adsorption and selective recognition ability of MIPs were evaluated using the equilibrium rebinding experiments. The results indicated that the prepared MIP showed a good selectivity recognition ability to its template. It concluded that MIP could be employed as an effective material for removing Congo red from waste water.

Preparation of a poly(styrene-co-DPHA-co-EDMA) monolith and its application for the separation of small molecules and biomacromolecules by HPLC.

PubMed

Wang, Xixi; Li, Xueying; Jiang, Xiaoya; Dong, Peipei; Liu, Haiyan; Bai, Ligai; Yan, Hongyuan

2017-04-01

A high performance liquid chromatography (HPLC) monolithic column was prepared by redox polymerization of styrene, dipentaerythritol hexaacrylate (DPHA) and ethylene glycol dimethacrylate (EDMA) in a porogen system of n-propanol/PEG400. The monolith was characterized by scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and the results indicated that the monolith had a stable and homogeneous structure. The porosity of the monolithic column was 75.86% and average pore diameter was 2.1µm. Several alkylbenzenes and anilines were used to evaluate the column performance in terms of hydrophobicity. Then the column was applied to separate small molecules including phytosterol and BSA tryptic digest. Finally, five standard proteins, egg white and plasma were separated respectively and high separation capacity of protein was obtained. Copyright © 2016 Elsevier B.V. All rights reserved.

Chromatographic properties PLOT multicapillary columns.

PubMed

Nikolaeva, O A; Patrushev, Y V; Sidelnikov, V N

2017-03-10

Multicapillary columns (MCCs) for gas chromatography make it possible to perform high-speed analysis of the mixtures of gaseous and volatile substances at a relatively large amount of the loaded sample. The study was performed using PLOT MCCs for gas-solid chromatography (GSC) with different stationary phases (SP) based on alumina, silica and poly-(1-trimethylsilyl-1-propyne) (PTMSP) polymer as well as porous polymers divinylbenzene-styrene (DVB-St), divinylbenzene-vinylimidazole (DVB-VIm) and divinylbenzene-ethylene glycol dimethacrylate (DVB-EGD). These MCCs have the efficiency of 4000-10000 theoretical plates per meter (TP/m) and at a column length of 25-30cm can separate within 10-20s multicomponent mixtures of substances belonging to different classes of chemical compounds. The sample amount not overloading the column is 0.03-1μg and depends on the features of a porous layer. Examples of separations on some of the studied columns are considered. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of thermo-responsive polymer brushes on hydrophilic polymeric beads by surface-initiated atom transfer radical polymerization for a highly resolutive separation of peptides.

PubMed

Mizutani, Aya; Nagase, Kenichi; Kikuchi, Akihiko; Kanazawa, Hideko; Akiyama, Yoshikatsu; Kobayashi, Jun; Annaka, Masahiko; Okano, Teruo

2010-09-17

Poly(N-isopropylacrylamide-co-N-tert-butylacrylamide) [P(IPAAm-co-tBAAm)] brushes were prepared on poly(hydroxy methacrylate) (PHMA) [hydrolyzed poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate)] beads having large pores by surface-initiated atom transfer radical polymerization (ATRP) and applied to the stationary phases of thermo-responsive chromatography. Optimized amount of copolymer brushes grafted PHMA beads were able to separate peptides and proteins with narrow peaks and a high resolution. The beads were found to have a specific surface area of 43.0 m(2)/g by nitrogen gas adsorption method. Copolymer brush of P(IPAAm-co-tBAAm) grafted PHMA beads improved the stationary phase of thermo-responsive chromatography for the all-aqueous separation of peptides and proteins. 2010 Elsevier B.V. All rights reserved.

Rechargeable Infection-responsive Antifungal Denture Materials

PubMed Central

Cao, Z.; Sun, X.; Yeh, C.-K.; Sun, Y.

2010-01-01

Candida-associated denture stomatitis (CADS) is a significant clinical concern. We developed rechargeable infection-responsive antifungal denture materials for potentially managing the disease. Polymethacrylic acid (PMAA) was covalently bound onto diurethane dimethacrylate denture resins in the curing step. The PMAA resins bound cationic antifungal drugs such as miconazole and chlorhexidine digluconate (CG) through ionic interactions. The anticandidal activities of the drug-containing PMAA-resin discs were sustained for a prolonged period of time (weeks and months). Drug release was much faster at acidic conditions (pH 5) than at pH 7. Drugs bound to the denture materials could be “washed out” by treatment with EDTA, and the drug-depleted resins could be recharged with the same or a different class of anticandidal drugs. These results suggest clinical potential of the newly developed antifungal denture materials in the management of CADS and other infectious conditions. PMID:20940361

Carprofen-imprinted monolith prepared by reversible addition-fragmentation chain transfer polymerization in room temperature ionic liquids.

PubMed

Ban, Lu; Han, Xu; Wang, Xian-Hua; Huang, Yan-Ping; Liu, Zhao-Sheng

2013-10-01

To obtain fast separation, ionic liquids were used as porogens first in combination with reversible addition-fragmentation chain transfer (RAFT) polymerization to prepare a new type of molecularly imprinted polymer (MIP) monolith. The imprinted monolithic column was synthesized using a mixture of carprofen (template), 4-vinylpyridine, ethylene glycol dimethacrylate, [BMIM]BF4, and chain transfer agent (CTA). Some polymerization factors, such as template-monomer molar ratio, the degree of crosslinking, the composition of the porogen, and the content of CTA, on the column efficiency and imprinting effect of the resulting MIP monolith were systematically investigated. Affinity screening of structurally similar compounds with the template can be achieved in 200 s on the MIP monolith due to high column efficiency (up to 12,070 plates/m) and good column permeability. Recognition mechanism of the imprinted monolith was also investigated.

Preparation of novel beta-cyclodextrin functionalized monolith and its application in chiral separation.

PubMed

Lv, Yongqin; Mei, Danping; Pan, Xinxin; Tan, Tianwei

2010-09-15

A novel beta-cyclodextrin (beta-CD) functionalized organic polymer monolith was prepared by covalently bonding ethylenediamine-beta-CD (EDA-beta-CD) to poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EGDMA)) monolith via ring opening reaction of epoxy groups. SEM characterization was performed to confirm the homogeneity of the monolithic polymer. The resulting monolith was then characterized by DSC and XPS elemental analysis to study the thermal stability of the monolith, and to prove the successful immobilization of beta-CD on the polymer substrate. The beta-CD ligand density of 0.68 mmol g(-1) was obtained for the modified monolith, indicating the high reactivity and efficiency of the EDA-beta-CD modifier. The ethylenediamine-beta-CD functionalized monoliths were used for the chiral separation of ibuprofen racemic mixture and showed promising results. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Molecularly Imprinted Polymer Nanoparticles for Formaldehyde Sensing with QCM

PubMed Central

Hussain, Munawar; Kotova, Kira; Lieberzeit, Peter A.

2016-01-01

Herein, we report on molecularly imprinted polymers (MIPs) for detecting formaldehyde vapors in air streams. A copolymer thin film consisting of styrene, methacrylic acid, and ethylene glycol dimethacrylate on quartz crystal microbalance (QCM) yielded a detection limit of 500 ppb formaldehyde in dry air. Surprisingly, these MIPs showed specific behavior when tested against a range of volatile organic compounds (VOCs), such as acetaldehyde, methanol, formic acid, and dichloromethane. Despite thus being a suitable receptor in principle, the MIPs were not useful for measurements at 50% humidity due to surface saturation by water. This was overcome by introducing primary amino groups into the polymer via allyl amine and by changing the coating morphology from thin film to nanoparticles. This led to the same limit of detection (500 ppb) and selectivity as before, but at the real-life conditions of 50% relative humidity. PMID:27376287

Experimental mixture design as a tool for the synthesis of antimicrobial selective molecularly imprinted monodisperse microbeads.

PubMed

Benito-Peña, Elena; Navarro-Villoslada, Fernando; Carrasco, Sergio; Jockusch, Steffen; Ottaviani, M Francesca; Moreno-Bondi, Maria C

2015-05-27

The effect of the cross-linker on the shape and size of molecular imprinted polymer (MIP) beads prepared by precipitation polymerization has been evaluated using a chemometric approach. Molecularly imprinted microspheres for the selective recognition of fluoroquinolone antimicrobials were prepared in a one-step precipitation polymerization procedure using enrofloxacin (ENR) as the template molecule, methacrylic acid as functional monomer, 2-hydroxyethyl methacrylate as hydrophilic comonomer, and acetonitrile as the porogen. The type and amount of cross-linker, namely ethylene glycol dimethacrylate, divinylbenzene or trimethylolpropane trimethacrylate, to obtain monodispersed MIP spherical beads in the micrometer range was optimized using a simplex lattice design. Particle size and morphology were assessed by scanning electron microscopy, dynamic light scattering, and nitrogen adsorption measurements. Electron paramagnetic resonance spectroscopy in conjunction with a nitroxide as spin probe revealed information about the microviscosity and polarity of the binding sites in imprinted and nonimprinted polymer beads.

Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

NASA Astrophysics Data System (ADS)

Hassmoro, N. F.; Rusop, M.; Abdullah, S.

2013-06-01

The differential microemulsion polymerization was used to synthesize latex nanoparticles. In this paper, 1, 3-butylene glycol dimethacrylate (1, 3-BGDMA) was used as a crosslinker respectively 1-5 weight% of monomer total. Butyl acrylate (BA), butyl methacrylate (BMA), and methacrylic acid (MAA) was used as the monomer. The thin film of latex nanoparticles were prepared by using spin coating method and have been dried at 100°C for 5 minutes. The amount of the crosslinker added in the polymerization was optimized and we found that the particle sizes fall in the range of 30-60 nm. The structural morphology of the uncrosslinked latex represented the most homogeneous image compared to the crosslinked latex. The effect of the amount of crosslinker on the particle sizes investigated by the Zeta-sizer Nano series while Atomic Force microscopy (AFM) was used to study the structural properties of latex nanoparticles.

Synthesis and characterization of magnetic and non-magnetic core-shell polyepoxide micrometer-sized particles of narrow size distribution.

PubMed

Omer-Mizrahi, Melany; Margel, Shlomo

2009-01-15

Core polystyrene microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2-methoxy ethanol. Uniform polyglycidyl methacrylate/polystyrene core-shell micrometer-sized particles were prepared by emulsion polymerization at 73 degrees C of glycidyl methacrylate in the presence of the core polystyrene microspheres. Core-shell particles with different properties (size, surface morphology and composition) have been prepared by changing various parameters belonging to the above seeded emulsion polymerization process, e.g., volumes of the monomer glycidyl methacrylate and the crosslinker monomer ethylene glycol dimethacrylate. Magnetic Fe(3)O(4)/polyglycidyl methacrylate/polystyrene micrometer-sized particles were prepared by coating the former core-shell particles with magnetite nanoparticles via a nucleation and growth mechanism. Characterization of the various particles has been accomplished by routine methods such as light microscopy, SEM, FTIR, BET and magnetic measurements.

[Preparation and evaluation of novel mesoporous molecular sieve of baicalin surface molecularly imprinted polymers].

PubMed

Gu, Xia-li; He, Hong-liang; Shi, Li-ying; Gao, Yan-kun; Chen, Li-na

2015-05-01

Taking mesoporous molecular sieve MCM-41 as a substrate, baicalin (BA) as template, acrylamide (AM) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent, ethanol as solvent, under thermal polymerization initiator of azobis isobutyronitrilo (AIBN) , a kind of selective recognition of baicalin surface molecularly imprinted polymer was synthesized. The surface morphologies and characteristics of the MIPs were characterized by infrared spectroscopy (IR) and transmission electron microscope (TEM). The adsorption properties of polymer microsphere for the template were tested by the dynamic adsorption equilibrium experiments and static adsorption equilibrium experiments. The experiment showed that the imprinting process was successfully and the well-ordered one-dimensional pore structure of MCM-41 was still preserved. Furthermore, molecularly imprinted polymers had higher selective ability for BA, then provided a new method for the efficient separation and enrichment of baicalin active ingredients from medicinal plants Scutellaria baicalensis.

Effect of filler properties in composite resins on light transmittance characteristics and color.

PubMed

Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Takahashi, Hideo; Ban, Seiji

2007-01-01

The purpose of this investigation was to examine the effect of filler particle size and shape as well as filler content on light transmittance characteristics and color of experimental composite resins. A mixture of 30 mol% Bis-GMA and 70 mol% TEGDMA was prepared as a base monomer and to which a photoinitiator (camphorquinone) and a co-initiator (N,N-dimethylaminoethyl methacrylate) were added. Four different irregular- and spherical-shaped filler types with an average particle size of 1.9-11.1 microm were added to the mixture in three different filler contents of 20, 30, and 40 vol%. Light transmittance characteristics including light diffusion characteristics of the materials were evaluated. Color values and color differences among filler contents of the materials were also determined. Materials containing smaller and irregular-shaped fillers showed higher light transmittance and diffusion angle distribution with a sharper peak, as compared with those containing larger and spherical-shape fillers. It was also found that there was a significant correlation between the specific surface area of fillers and the color difference of the materials containing the fillers. Our results indicated that the shape of filler particles, as well as particle size and filler content, significantly affected the light transmittance characteristics--including light diffusion characteristics--and color of composite resins.

Synthesis and properties of magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes for magnetic extraction of bisphenol A from water.

PubMed

Zhang, Zhaohui; Chen, Xing; Rao, Wei; Chen, Hongjun; Cai, Rong

2014-08-15

Novel magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes (MWNTs@MMIPs) with specific selectivity toward bisphenol A were synthesized using bisphenol A as the template molecule, methacrylic acid, and β-cyclodextrin as binary functional monomers and ethylene glycol dimethacrylate as the cross-linker. The MWNTs@MMIPs were characterized by Fourier transform infrared, vibrating sample magnetometer, and transmission electron microscopy. Batch mode adsorption experiment was carried out to investigate the specific adsorption equilibrium and kinetics of the MWNTs@MMIPs. The MWNTs@MMIPs exhibited good affinity with a maximum adsorption capacity of 49.26 μmol g(-1) and excellent selectivity toward bisphenol A. Combined with high-performance liquid chromatography analysis, the MWNTs@MMIPs were employed to extract bisphenol A in tap water, rain water, and lake water successfully with the recoveries of 89.8-95.4, 89.9-93.4, and 87.3-94.1%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Hyperbranched PEGmethacrylate linear pDMAEMA block copolymer as an efficient non-viral gene delivery vector.

PubMed

Mathew, Asha; Cao, Hongliang; Collin, Estelle; Wang, Wenxin; Pandit, Abhay

2012-09-15

A unique hyperbranched polymeric system with a linear poly-2-dimethylaminoethyl methacrylate (pDMAEMA) block and a hyperbranched polyethylene glycol methyl ether methacrylate (PEGMEMA) and ethylene dimethacrylate (EGDMA) block was designed and synthesized via deactivation enhanced atom transfer radical polymerisation (DE-ATRP) for efficient gene delivery. Using this unique structure, with a linear pDMAEMA block, which efficiently binds to plasmid DNA (pDNA) and hyperbranched polyethylene glycol (PEG) based block as a protective shell, we were able to maintain high transfection levels without sacrificing cellular viability even at high doses. The transfection capability and cytotoxicity of the polymers over a range of pDNA concentration were analysed and the results were compared to commercially available transfection vectors such as polyethylene imine (branched PEI, 25 kDa), partially degraded poly(amido amine)dendrimer (dPAMAM; commercial name: SuperFect(®)) in fibroblasts and adipose tissue derived stem cells (ADSCs). Copyright © 2012 Elsevier B.V. All rights reserved.

Molecularly imprinted polymers for RGD selective recognition and separation.

PubMed

Papaioannou, Emmanuel; Koutsas, Christos; Liakopoulou-Kyriakides, Maria

2009-03-01

Molecularly imprinted polymers that could recognize the tripeptide Arg-Gly-Asp have been produced with the use of two functional monomers and three different cross-linkers, respectively. Methacrylic acid and acrylamide were used as functional monomers and the role of the ethylene glycol dimethacrylate, trimethylpropane trimethacrylate and N,N'-methylene-bisacrylamide as crosslinking monomers, was investigated on their recognition capability. The % net rebinding and the imprinting factor values were obtained, giving for the methacrylic acid-trimethylpropane trimethacrylate polymer the highest values 12.3% and 2.44, respectively. In addition, this polymer presented lower dissociation constant (K(D)) value and the higher B (max)% of theoretical total binding sites than all the other polymers. Rebinding experiments with Lys-Gly-Asp, an analogue of Arg-Gly-Asp, and other different peptides, such as cholecystokinin C-terminal tri- and pentapeptide and gramicidin, further indicated the selectivity of methacrylic acid-trimethylpropane trimethacrylate copolymer for Arg-Gly-Asp giving specific selectivity factor values 1.27, 1.98, 1.31 and 1.67, respectively.

On the influence of crosslinker on template complexation in molecularly imprinted polymers: a computational study of prepolymerization mixture events with correlations to template-polymer recognition behavior and NMR spectroscopic studies.

PubMed

Shoravi, Siamak; Olsson, Gustaf D; Karlsson, Björn C G; Nicholls, Ian A

2014-06-12

Aspects of the molecular-level basis for the function of ethylene glycol dimethacrylate and trimethylolproprane trimethacrylate crosslinked methacrylic acid copolymers molecularly imprinted with (S)-propranolol have been studied using a series of all-component and all-atom molecular dynamics studies of the corresponding prepolymerization systems. The crosslinking agents were observed to contribute to template complexation, and the results were contrasted with previously reported template-recognition behavior of the corresponding polymers. Differences in the extent to which the two crosslinkers interacted with the functional monomer were identified, and correlations were made to polymer-ligand recognition behavior and the results of nuclear magnetic resonance spectroscopic studies studies. This study demonstrates the importance of considering the functional monomer-crosslinker interaction when designing molecularly imprinted polymers, and highlights the often neglected general contribution of crosslinker to determining the nature of molecularly imprinted polymer-template selectivity.

Effect of ultraviolet light irradiation period on bond strengths between fiber-reinforced composite post and core build-up composite resin.

PubMed

Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

2014-01-01

The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett's comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.

Preparation of polyhedral oligomeric silsesquioxane based imprinted monolith.

PubMed

Li, Fang; Chen, Xiu-Xiu; Huang, Yan-Ping; Liu, Zhao-Sheng

2015-12-18

Polyhedral oligomeric silsesquioxane (POSS) was successfully applied, for the first time, to prepare imprinted monolithic column with high porosity and good permeability. The imprinted monolithic column was synthesized with a mixture of PSS-(1-Propylmethacrylate)-heptaisobutyl substituted (MA 0702), naproxon (template), 4-vinylpyridine, and ethylene glycol dimethacrylate, in ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4). The influence of synthesis parameters on the retention factor and imprinting effect, including the amount of MA 0702, the ratio of template to monomer, and the ratio of monomer to crosslinker, was investigated. The greatest imprinting factor on the imprinted monolithic column prepared with MA 0702 was 22, about 10 times higher than that prepared in absence of POSS. The comparisons between MIP monoliths synthesized with POSS and without POSS were made in terms of permeability, column efficiency, surface morphology and pore size distribution. In addition, thermodynamic and Van Deemter analysis were used to evaluate the POSS-based MIP monolith. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and Evaluation of a Molecularly Imprinted Polymer for the Determination of Metronidazole in Water Samples.

PubMed

de León-Martínez, L Díaz; Rodríguez-Aguilar, M; Ocampo-Pérez, R; Gutiérrez-Hernández, J M; Díaz-Barriga, F; Batres-Esquivel, L; Flores-Ramírez, R

2018-03-01

A molecularly imprinted polymer was developed and evaluated for selective determination of metronidazole (MNZ) in wastewater. This was achieved by using sodium methacrylate as monomer, toluene as porogen, ethylene glycol dimethacrylate as crosslinker, azobisisobutyronitrile as initiator and metronidazole as template molecule to generate the selectivity of the polymer for the compound, as well as non-imprinted polymers were synthesized. Two different polymerization approaches were used, bulk and emulsion and the polymers obtained by emulsion presented higher retention percentages the MIP 2-M presented the higher retention (83%). The performed method, was validated in fortified water, showing linearity from 10 up to 1000 ng/mL; limit of detection and quantification for compound were between 3 and 10 ng/mL, respectively. Finally, the method was applied in samples of a wastewater treatment plant in the city of San Luis Potosí, México, and the concentrations of MNZ in these samples were 84.1-114 ng/mL.

Reduced Graphene Oxide-Hybridized Polymeric High-Internal Phase Emulsions for Highly Efficient Removal of Polycyclic Aromatic Hydrocarbons from Water Matrix.

PubMed

Huang, Yipeng; Zhang, Wenjuan; Ruan, Guihua; Li, Xianxian; Cong, Yongzheng; Du, Fuyou; Li, Jianping

2018-03-27

Reduced graphene oxide (RGO)-hybridized polymeric high-internal phase emulsions (RGO/polyHIPEs) with an open-cell structure and hydrophobicity have been successfully prepared using 2-ethylhexyl acrylate and ethylene glycol dimethacrylate as the monomer and the cross-linker, respectively. The adsorption mechanism and performance of this RGO/polyHIPEs to polycyclic aromatic hydrocarbons (PAHs) were investigated. Adsorption isotherms of PAHs on RGO/polyHIPEs show that the saturated adsorption capacity is 47.5 mg/g and the equilibrium time is 8 h. Cycling tests show that the adsorption capacity of RGO/polyHIPEs remains stable in 10 adsorption-desorption cycles without observable structure change in RGO/polyHIPEs. Moreover, the PAH residues in water samples after being purified by RGO/polyHIPEs are lower than the limit values in drinking water set by the European Food Safety Authority. These results demonstrate that the RGO/polyHIPEs have great potentiality in PAH removal and water purification.

Synthesis and Characterization of Carboxymethylcellulose-Methacrylate Hydrogel Cell Scaffolds

PubMed Central

Reeves, Robert; Ribeiro, Andreia; Lombardo, Leonard; Boyer, Richard; Leach, Jennie B.

2012-01-01

Many carbohydrates pose advantages for tissue engineering applications due to their hydrophilicity, degradability, and availability of chemical groups for modification. For example, carboxymethylcellulose (CMC) is a water-soluble cellulose derivative that is degradable by cellulase. Though this enzyme is not synthesized by mammalian cells, cellulase and the fragments derived from CMC degradation are biocompatible. With this in mind, we created biocompatible, selectively degradable CMC-based hydrogels that are stable in routine culture, but degrade when exposed to exogenous cellulase. Solutions of CMC-methacrylate and polyethylene glycol dimethacrylate (PEG-DM) were co-crosslinked to form stable hydrogels; we found that greater CMC-methacrylate content resulted in increased gel swelling, protein diffusion and rates of degradation by cellulase, as well as decreased gel shear modulus. CMC-methacrylate/PEG-DM gels modified with the adhesive peptide RGD supported fibroblast adhesion and viability. We conclude that hydrogels based on CMC-methacrylate are suitable for bioengineering applications where selective degradability may be favorable, such as cell scaffolds or controlled release devices. PMID:22708058

Radiation crosslinking of highly plasticized PVC

NASA Astrophysics Data System (ADS)

Mendizabal, E.; Cruz, L.; Jasso, C. F.; Burillo, G.; Dakin, V. I.

1996-02-01

To improve the physical properties of highly plasticized PVC, the polymer was crosslinked by gamma irradiation using a dose rate of 91 kGy/h. The effect of plasticizer type was studied by using three different plasticizers, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), di(2-ethyl hexyl) phthalate (DOP), and di(2-ethylhexyl terephthalate) (DOTP), and varying irradiation doses. Gel content was determined by soxhlet extraction, tensile measurements were made on a universal testing machine and the mechano-dynamic measurements were made in a dynamic rheometer. It was found that a considerable bonding of plasticizer molecules to macromolelcules takes place along with crosslinking, so that the use of the solvent extraction method for measuring the degree of crosslinking can give erroneous information. Radiation-chemical crosslinking yield ( Gc) and molecular weight of interjunctions chains ( Mc), were calculated for different systems studied. Addition of ethylene glycol dimethacrylate (EGDM) as a crosslinking coagent and dioctyl tin oxide (DOTO) as a stabilizer was also studied. Plasticizers extraction resistance was increased by irradiation treatment.

Water-compatible molecularly imprinted polymers for efficient direct injection on-line solid-phase extraction of ropivacaine and bupivacaine from human plasma.

PubMed

Cobb, Zoe; Sellergren, Börje; Andersson, Lars I

2007-12-01

Two novel molecularly imprinted polymers (MIPs) selected from a combinatorial library of bupivacaine imprinted polymers were used for selective on-line solid-phase extraction of bupivacaine and ropivacaine from human plasma. The MIPs were prepared using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linking monomer and in addition hydroxyethylmethacrylate to render the polymer surface hydrophilic. The novel MIPs showed high selectivity for the analytes and required fewer and lower concentrations of additives to suppress non-specific adsorption compared with a conventional MIP. This enabled the development of an on-line system for direct extraction of buffered plasma. Selective extraction was achieved without the use of time-consuming solvent switch steps, and transfer of the analytes from the MIP column to the analytical column was carried out under aqueous conditions fully compatible with reversed-phase LC gradient separation of analyte and internal standard. The MIPs showed excellent aqueous compatibility and yielded extractions with acceptable recovery and high selectivity.

A novel chiral separation material: polymerized organogel formed by chiral gelators for the separation of D- and L-phenylalanine.

PubMed

Fu, Xinjian; Yang, Yang; Wang, Ningxia; Wang, Hong; Yang, Yajiang

2007-01-01

N-Stearine-N'-stearyl-L-phenylalanine, a chiral compound, was synthesized and used as a gelator for the gelation of polymerizable solvents, such as ss-hydroxyethyl methacrylate (HEMA), styrene, etc. The scanning electron microscope (SEM) images of the gelator aggregates show fibril-like helices, typical chiral aggregates with diameters of 100-200 nm. The solvent molecules were immobilized by capillary forces in the three-dimensional network structures of the organogels. The HEMA organogels containing crosslinker polyethylene glycol dimethacrylates (PEG200DMA) were subsequently polymerized by in situ UV irradiation. A porous polymerized organogels were obtained after removal of gelator aggregates through ethanol extraction. The chiral separation of D- and L-phenylalanine was carried out by the adsorption of the polymerized organogels. The adsorption efficiency of L-phenylalanine on the polymerized organogels was found to be dependent on the concentration of the gelator and crosslinker. (c) 2007 John Wiley & Sons, Ltd.

Design and in vitro evaluation of a novel poly(methacrylic acid)/metronidazole antibacterial nanogel as an oral dosage form.

PubMed

Chen, Tao; Chen, Liang; Li, Haicheng; Chen, Yuhui; Guo, Huixin; Shu, Yang; Chen, Zhiyu; Cai, Changhui; Guo, Lina; Zhang, Xianen; Zhou, Lin; Zhong, Qiu

2014-06-01

To overcome the undesirable side-effects of metronidazole (MTZ), ethylene glycol dimethacrylate is used as the cross-linker, and a series of poly(methacrylic acid) (PMAA) nanogels were prepared to load the MTZ. We investigated the morphology, size, in vitro release property in the simulated gastrointestinal medium, long-term antibacterial performance against Bacteroides fragilis, cytotoxicity, stability and activity of this novel MTZ/PMAA nanogel. The results indicate that the MTZ/PMAA nanogel sustained the release of MTZ in long-term antibacterial activity in the simulated gastrointestinal medium. This MTZ/PMAA nanogel exhibits less cytotoxicity than MTZ alone, suggesting that MTZ/PMAA nanogel is a more useful dosage form than MTZ for mild-to-moderate Clostridium difficile infections. The novel aspects of this study include the synthesis of a nanogel and the three-phase study of the release profile, which might be useful for other researchers in this field. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Affinity monolith-integrated poly(methyl methacrylate) microchips for on-line protein extraction and capillary electrophoresis.

PubMed

Sun, Xiuhua; Yang, Weichun; Pan, Tao; Woolley, Adam T

2008-07-01

Immunoaffinity monolith pretreatment columns have been coupled with capillary electrophoresis separation in poly(methyl methacrylate) (PMMA) microchips. Microdevices were designed with eight reservoirs to enable the electrically controlled transport of selected analytes and solutions to carry out integrated immunoaffinity extraction and electrophoretic separation. The PMMA microdevices were fabricated reproducibly and with high fidelity by solvent imprinting and thermal bonding methods. Monoliths with epoxy groups for antibody immobilization were prepared by direct in situ photopolymerization of glycidyl methacrylate and ethylene glycol dimethacrylate in a porogenic solvent consisting of 70% 1-dodecanol and 30% cyclohexanol. Antifluorescein isothiocyanate was utilized as a model affinity group in the monoliths, and the immobilization process was optimized. A mean elution efficiency of 92% was achieved for the monolith-based extraction of fluorescein isothiocyanate (FITC)-tagged human serum albumin. FITC-tagged proteins were purified from a contaminant protein and then separated electrophoretically using these devices. The developed immunoaffinity column/capillary electrophoresis microdevices show great promise for combining sample pretreatment and separation in biomolecular analysis.

Affinity Monolith-Integrated Poly(methyl Methacrylate) Microchips for On-Line Protein Extraction and Capillary Electrophoresis

PubMed Central

Sun, Xiuhua; Yang, Weichun; Pan, Tao; Woolley, Adam T.

2008-01-01

Immunoaffinity monolith pretreatment columns have been coupled with capillary electrophoresis separation in poly(methyl methacrylate) (PMMA) microchips. Microdevices were designed with 8 reservoirs to enable the electrically controlled transport of selected analytes and solutions to carry out integrated immunoaffinity extraction and electrophoretic separation. The PMMA microdevices were fabricated reproducibly and with high fidelity by solvent imprinting and thermal bonding methods. Monoliths with epoxy groups for antibody immobilization were prepared by direct in-situ photopolymerization of glycidyl methacrylate and ethylene dimethacrylate in a porogenic solvent consisting of 70% dodecanol and 30% hexanol. Anti-fluorescein isothiocyanate (FITC) was utilized as a model affinity group in the monoliths, and the immobilization process was optimized. A mean elution efficiency of 92% was achieved for the monolith-based extraction of FITC-tagged human serum albumin. FITC-tagged proteins were purified from a contaminant protein and then separated electrophoretically using these devices. The developed immunoaffinity column/capillary electrophoresis microdevices show great promise for combining sample pretreatment and separation in biomolecular analysis. PMID:18479142

Comparison of polymer induced and solvent induced trypsin denaturation: the role of hydrophobicity.

PubMed

Jasti, Lakshmi S; Fadnavis, Nitin W; Addepally, Uma; Daniels, Siona; Deokar, Sarika; Ponrathnam, Surendra

2014-04-01

Trypsin adsorption from aqueous buffer by various copolymers of allyl glycidyl ether-ethylene glycol dimethacrylate (AGE-EGDM) copolymer with varying crosslink density increases with increasing crosslink density and the effect slowly wears off after reaching a plateau at 50% crosslink density. The copolymer with 25% crosslink density was reacted with different amines with alkyl/aryl side chains to obtain a series of copolymers with 1,2-amino alcohol functional groups and varying hydrophobicity. Trypsin binding capacity again increases with hydrophobicity of the reacting amine and a good correlation between logPoctanol of the amine and protein binding is observed. The bound trypsin is denatured to the extent of 90% in spite of the presence of hydrophilic hydroxyl and amino groups. The behavior was comparable to that in mixtures of aqueous buffer and water-miscible organic co-solvents where the solvent concentration required to deactivate 50% of the enzyme (C50) is dependent on logPoctanol of the co-solvent. Copyright © 2014 Elsevier B.V. All rights reserved.

Novel beta-cyclodextrin derivative functionalized polymethacrylate-based monolithic columns for enantioselective separation of ibuprofen and naproxen enantiomers in capillary electrochromatography.

PubMed

Tian, Yun; Zhong, Cheng; Fu, Enqin; Zeng, Zhaorui

2009-02-06

A novel enantioselective polymethacrylate-based monolithic column for capillary electrochromatography was prepared by ring-opening reaction of epoxy groups from poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith with a novel beta-cyclodextrin derivative bearing 4-dimethylamino-1,8-naphthalimide functionalities. Conditions for the ring-opening reaction with respect to different reaction parameters were thoroughly optimized to obtain high electroosmotic flow, separation efficiency and enantioselectivity for the analytes. The nonaqueous mobile phase composition regarding acetonitrile-methanol ratio and the concentration of electrolyte were examined to manipulate the hydrophobic inclusion and anion-exchange interaction between the analytes and chiral stationary phase. It was observed that in addition to beta-cyclodextrin cavity, the electrostatic interaction exhibited pronounced influence on the enantioseparation of acidic analytes. Acidic enantiomers (ibuprofen and naproxen) could be separated with separation factor (alpha) values up to 1.08 and a maximum separation efficiency of 86000 plates/m could be achieved.

Determination of L-phenylalanine on-line based on molecularly imprinted polymeric microspheres and flow injection chemiluminescence

NASA Astrophysics Data System (ADS)

Qiu, Huamin; Xi, Yulei; Lu, Fuguang; Fan, Lulu; Luo, Chuannan

2012-02-01

A novel molecular imprinting-chemiluminescence (MIP-CL) sensor for the determination of L-phenylalanine (Phe) using molecularly imprinted polymer (MIP) as recognition element is reported. The Phe-MIP was synthesized using acrylamide (AM) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker, 2,2-azobisisobutyronitrile (AIBN) as initiator and the polymers' properties were characterized. Then the synthesized MIP was employed as recognition element by packing into flow cell to establish a novel flow injection CL sensor. The CL intensity responded linearly to the concentration of Phe in the range 1.3 × 10 -6 to 5.44 × 10 -4 mol/L with a detection limit of 6.23 × 10 -7 mol/L (3 σ), which is lower than that of conventional methods. The sensor is reusable and has a great improvement in sensitivity and selectivity for CL analysis. As a result, the new MIP-CL sensor had been successfully applied to the determination of Phe in samples.

Molecular Imprinting of Silica Nanoparticle Surfaces via Reversible Addition-Fragmentation Polymerization for Optical Biosensing Applications

NASA Astrophysics Data System (ADS)

Oluz, Zehra; Nayab, Sana; Kursun, Talya Tugana; Caykara, Tuncer; Yameen, Basit; Duran, Hatice

Azo initiator modified surface of silica nanoparticles were coated via reversible addition-fragmentation polymerization (RAFT) of methacrylic acid and ethylene glycol dimethacrylate using 2-phenylprop 2-yl dithobenzoate as chain transfer agent. Using L-phenylalanine anilide as template during polymerization led molecularly imprinted nanoparticles. RAFT polymerization offers an efficient control of grafting process, while molecularly imprinted polymers shows enhanced capacity as sensor. L-phenylalanine anilide imprinted silica particles were characterized by X-Ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM). Performances of the particles were followed by surface plasmon resonance spectroscopy (SPR) after coating the final product on gold deposited glass substrate against four different analogous of analyte molecules: D-henylalanine anilide, L-tyrosine, L-tryptophan and L-phenylalanine. Characterizations indicated that silica particles coated with polymer layer do contain binding sites for L-phenylalanine anilide, and are highly selective for the molecule of interest. This project was supported by TUBITAK (Project No:112M804).

Insufficient cure under the condition of high irradiance and short irradiation time.

PubMed

Feng, Li; Carvalho, Ricardo; Suh, Byoung I

2009-03-01

To investigate if and why a plasma arc curing (PAC) light tends to undercure methacrylate-based resins or resin composites. Model dimethacrylate resins, commercial dental adhesives, and commercial resin composites were cured using a PAC light and a halogen light with the similar radiant exposures but different combinations of irradiance and irradiation time. The degree of double bond conversion (DC) was measured with FTIR spectroscopy and analyzed as a function of radiant exposure. The PAC light produced a lower DC than the halogen light for the model resin with the lowest viscosity and for three of the four adhesives. With a high irradiance, the PAC light could cure three of the four composites as thoroughly as its halogen counterpart. When the irradiance was reduced, however, three composites yielded a lower DC. Insufficient cure by PAC lights or any curing lights with very high irradiance is likely to happen when too short an irradiation time is used. It is because under higher irradiance, the lifetime of free radicals is shorter.

Phospholipid arrays on porous polymer coatings generated by micro-contact spotting

PubMed Central

de Freitas, Monica; Tröster, Lea-Marie; Jochum, Tobias; Levkin, Pavel A; Hirtz, Michael; Fuchs, Harald

2017-01-01

Nanoporous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (HEMA-EDMA) is used as a 3D mesh for spotting lipid arrays. Its porous structure is an ideal matrix for lipid ink to infiltrate, resulting in higher fluorescent signal intensity as compared to similar arrays on strictly 2D substrates like glass. The embedded lipid arrays show high stability against washing steps, while still being accessible for protein and antibody binding. To characterize binding to polymer-embedded lipids we have applied Streptavidin as well as biologically important biotinylated androgen receptor binding onto 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(cap biotinyl) (Biotinyl Cap PE) and anti-DNP IgE recognition of 2,4-dinitrophenyl[1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[6-[(2,4-dinitrophenyl)amino]hexanoyl] (DNP)] antigen. This approach adds lipid arrays to the range of HEMA polymer applications and makes this solid substrate a very attractive platform for a variety of bio-applications. PMID:28487815

Synthesis of molecular imprinting polymers for extraction of gallic acid from urine.

PubMed

Bhawani, Showkat Ahmad; Sen, Tham Soon; Ibrahim, Mohammad Nasir Mohammad

2018-02-21

The molecularly imprinted polymers for gallic acid were synthesized by precipitation polymerization. During the process of synthesis a non-covalent approach was used for the interaction of template and monomer. In the polymerization process, gallic acid was used as a template, acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker and 2,2'-azobisisobutyronitrile as an initiator and acetonitrile as a solvent. The synthesized imprinted and non-imprinted polymer particles were characterized by using Fourier-transform infrared spectroscopy and scanning electron microscopy. The rebinding efficiency of synthesized polymer particles was evaluated by batch binding assay. The highly selective imprinted polymer for gallic acid was MIPI1 with a composition (molar ratio) of 1:4:20, template: monomer: cross-linker, respectively. The MIPI1 showed highest binding efficiency (79.50%) as compared to other imprinted and non-imprinted polymers. The highly selective imprinted polymers have successfully extracted about 80% of gallic acid from spiked urine sample.

Separation and enrichment of trace ractopamine in biological samples by uniformly-sized molecularly imprinted polymers

PubMed Central

Li, Ya; Fu, Qiang; Liu, Meng; Jiao, Yuan-Yuan; Du, Wei; Yu, Chong; Liu, Jing; Chang, Chun; Lu, Jian

2012-01-01

In order to prepare a high capacity packing material for solid-phase extraction with specific recognition ability of trace ractopamine in biological samples, uniformly-sized, molecularly imprinted polymers (MIPs) were prepared by a multi-step swelling and polymerization method using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and toluene as a porogen respectively. Scanning electron microscope and specific surface area were employed to identify the characteristics of MIPs. Ultraviolet spectroscopy, Fourier transform infrared spectroscopy, Scatchard analysis and kinetic study were performed to interpret the specific recognition ability and the binding process of MIPs. The results showed that, compared with other reports, MIPs synthetized in this study showed high adsorption capacity besides specific recognition ability. The adsorption capacity of MIPs was 0.063 mmol/g at 1 mmol/L ractopamine concentration with the distribution coefficient 1.70. The resulting MIPs could be used as solid-phase extraction materials for separation and enrichment of trace ractopamine in biological samples. PMID:29403774

'Click Chemistry' in the preparation of porous polymer-basedparticulate stationary phases for mu-HPLC separation of peptides andproteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slater, Michael; Snauko, Marian; Svec, Frantisek

With the use of the copper(I)-catalyzed (3 + 2) azide-alkynecycloaddition, an element of "click chemistry," stationary phasescarrying long alkyl chains or soybean trypsin inhibitor have beenprepared for use in HPLC separations in the reversed-phase and affinitymodes, respectively. The ligands were attached via a triazole ring tosize monodisperse porous beads containing either alkyne or azide pendantfunctionalities. Alkyne-containing beads prepared by directcopolymerization of propargyl acrylate with ethylene dimethacrylate wereallowed to react with azidooctadecane to give a reversed-phase sorbent.Azide-functionalized beads were prepared by chemical modification ofglycidyl methacrylate particles. Subsequent reaction with a terminalaliphatic alkyne produced a reversed-phase sorbent similar to thatobtained from themore » alkyne beads. Soybean trypsin inhibitor wasfunctionalized with N-(4-pentynoyloxy) succinimide to carry alkyne groupsand then allowed to react with the azide-containing beads to produce anaffinity sorbent for trypsin. The performance of these stationary phaseswas demonstrated with the HPLC separations of a variety of peptides andproteins.« less

Spectrophotometric Evaluation of Colour Stability of Nano Hybrid Composite Resin in Commonly Used Food Colourants in Asian Countries.

PubMed

Chittem, Jyothi; Sajjan, Girija S; Varma Kanumuri, Madhu

2017-01-01

There is growing interest in colour stability of aesthetic restorations. So far few studies have been reported. This study was designed to investigate the effects of different common food colourants i.e., Turmeric and Carmoisine (orange red dye) consumed by patients in Asian countries on a recent nano hybrid composite resin. A total of sixty disk shaped specimens measuring 10 mm in diameter and 2 mm in thickness were prepared. The samples were divided into two groups {Z 100 (Dental restorative composite) Filtek Z 250 XT (Nano hybrid universal restorative)}. Baseline colour measurement of all specimens were made using reflectance spectrophotometer with CIE L*a*b* system. Specimens were immersed in artificial saliva and different experimental solutions containing food colourants (carmoisine solution and turmeric solution) for three hours per day at 37°C. Colour measurements were made after 15 days. Colour difference (ΔE*) was calculated. Mean values were compared by one-way analysis of variance (ANOVA). Multiple range test by Tukey Post-hoc test procedure was employed to identify the significant groups at 5% level. Z 100 showed minimum staining capacity when compared to Z 250 XT in both the colourant solutions. The nanohybrid composite resin containing TEGDMA showed significant colour change when compared to that of microhybrid composite resin as a result of staining in turmeric and carmoisine solution.

Effect of different photo-initiators and light curing units on degree of conversion of composites.

PubMed

Brandt, William Cunha; Schneider, Luis Felipe Jochims; Frollini, Elisabete; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

2010-01-01

The aim of this study was to evaluate: (i) the absorption of photo-initiators and emission spectra of light curing units (LCUs); and (ii) the degree of conversion (DC) of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ) and/ or 1-phenyl-1,2-propanedione (PPD) were prepared. Dimethylaminoethyl methacrylate (DMAEMA) was used as co-initiator. Each mixture was loaded with 65 wt% of silanated filler particles. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE) and two lightemitting diode (LED) LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent) were used for activation procedures. Irradiance (mW/cm²) was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000). The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G). DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to two-way ANOVA and Tukey's test (5%). No significant difference was found for DC values when using LED LCUs regardless of the photo-initiator type. However, PPD showed significantly lower DC values than composites with CQ when irradiated with QTH. PPD produced DC values similar to those of CQ, but it was dependent on the LCU type.

Evaluation of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental dental resin-based materials.

PubMed

Oliveira, Dayane Carvalho Ramos Salles de; Souza-Junior, Eduardo José; Dobson, Adam; Correr, Ana Rosa Costa; Brandt, William Cunha; Sinhoreti, Mário Alexandre Coelho

2016-01-01

To evaluate the influence of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental resin-based materials photoactivated using different light curing units (LCUs). Experimental resin-based materials with the same organic matrix (60:40 wt% BisGMA:TEGDMA) were mechanically blended using a centrifugal mixing device. To this blend, different photoinitiator systems were added in equimolar concentrations with aliphatic amine doubled by wt%: 0.4 wt% CQ; 0.38 wt% PPD; or 0.2 wt% CQ and 0.19 wt% PPD. The degree of conversion (DC), flexural strength (FS), Young's modulus (YM), Knoop hardness (KNH), crosslinking density (CLD), and yellowing (Y) were evaluated (n=10). All samples were light cured with the following LCUs: a halogen lamp (XL 2500), a monowave LED (Radii), or a polywave LED (Valo) with 16 J/cm2. The results were analysed by two-way ANOVA and Tukey's test (α=0.05). No statistical differences were found between the different photoinitiator systems to KNH, CLS, FS, and YM properties (p≥0.05). PPD/CQ association showed the higher DC values compared with CQ and PPD isolated systems when photoactivated by a polywave LED (p≤0.05). Y values were highest for the CQ compared with the PPD systems (p≤0.05). PPD isolated system promoted similar chemical and mechanical properties and less yellowing compared with the CQ isolated system, regardless of the LCU used.

Optimizing light-cured composite through variations in camphorquinone and butylhydroxytoluene concentrations.

PubMed

Nassar, Hani; Chu, Tien-Min; Platt, Jeffrey

2016-05-20

The use of a free-radical polymerization inhibitor, butylhydroxytoluene (BHT), and a common photo-initiator, camphorquinone (CQ), to reduce polymerization stress in dental composite was investigated in this study. Samples were prepared by mixing Bis-GMA, UDMA, and TEGDMA at a 1:1:1 ratio (wt%), and silanized borosilicate glass fillers at 70 wt% were added to form the composite. Sixteen groups of resin composite were prepared using combinations of four CQ (0.1%, 0.5%, 1.0%, and 1.5%) and four BHT (0.0%, 0.5%, 1.0%, and 1.5%) concentrations. For each group, six properties were tested, including flexural strength (FS), flexural modulus (FM), degree of conversion (DC), contraction stress (CS), stress rate, and gel point (GP). The effects of CQ and BHT combinations on each of these properties were evaluated using two-way analysis of variance (ANOVA) and Fisher's Protected Least Significant Differences test at the 5% significance level. Groups with low CQ and BHT showed moderate values for FS, FM, and CS with a 70% DC. Increasing the BHT concentration caused a decrease in CS and DC with an increase in GP values. Increasing the CQ content led to a steady increase in values for FS and FM. High CQ and BHT combinations showed the most promising values for mechanical properties with low stress values.

Monomer Release from Resin Based Dental Materials Cured With LED and Halogen Lights

PubMed Central

Ak, Asli Topaloglu; Alpoz, A. Riza; Bayraktar, Oguz; Ertugrul, Fahinur

2010-01-01

Objectives: To measure the release of TEGDMA and BisGMA from two commercially available composite resins; Filtek Z 250 (3M ESPE, Germany), Leaddent (Leaddent, Germany) and two fissure sealants; Helioseal F (3M ESPE, Germany) Enamel Loc (Premiere Rev, USA) over 1, 3 and 7 days after polymerization with standard quartz-tungsten halogen Coltolux II (QHL) (Coltene Switzerland) and a standard blue light emitting diode Elipar Freelight 2 (3M ESPE, Germany). Methods: 9 samples of each material were placed in disc shaped specimens in 1 mm of thickness and 10 mm in diameter (n=36). Each material was polymerized using LED for 20 s (n=12), 40 s (n=12) and halogen for 40 s (n=12), respectively. High Performance Liquid Chromatography (HPLC) was used to measure the amount of monomers released over 1, 3 and 7 days. Data was analyzed using one way ANOVA and Bonferroni test for multiple comparisons with a significance level of .05. Results: LED 20 sec group showed the highest release of monomers at 1, 3 and 7 days in sealant groups. Halogen 40 sec group resulted highest release of monomers for Leaddent at all time intervals (P<.05) Conclusions: Efficiency of the curing unit and applying the recommended curing time of the light activated resin based dental materials is very important to protect the patient from potential hazards of residual monomers. PMID:20046478

Fabrication and characterisation of a novel biomimetic anisotropic ceramic/polymer-infiltrated composite material.

PubMed

Al-Jawoosh, Sara; Ireland, Anthony; Su, Bo

2018-04-10

To fabricate and characterise a novel biomimetic composite material consisting of aligned porous ceramic preforms infiltrated with polymer. Freeze-casting was used to fabricate and control the microstructure and porosity of ceramic preforms, which were subsequently infiltrated with 40-50% by volume UDMA-TEGDMA polymer. The composite materials were then subjected to characterisation, namely density, compression, three-point bend, hardness and fracture toughness testing. Samples were also subjected to scanning electron microscopy and computerised tomography (Micro-CT). Three-dimensional aligned honeycomb-like ceramic structures were produced and full interpenetration of the polymer phase was observed using micro-CT. Depending on the volume fraction of the ceramic preform, the density of the final composite ranged from 2.92 to 3.36g/cm 3 , compressive strength ranged from 206.26 to 253.97MPa, flexural strength from 97.73 to 145.65MPa, hardness ranged from 1.46 to 1.62GPa, and fracture toughness from 3.91 to 4.86MPam 1/2 . Freeze-casting provides a novel method to engineer composite materials with a unique aligned honeycomb-like interpenetrating structure, consisting of two continuous phases, inorganic and organic. There was a correlation between the ceramic fraction and the subsequent, density, strength, hardness and fracture toughness of the composite material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Concentration dependent survival and neural differentiation of murine embryonic stem cells cultured on polyethylene glycol dimethacrylate hydrogels possessing a continuous concentration gradient of n-cadherin derived peptide His-Ala-Val-Asp-Lle.

PubMed

Lim, Hyun Ju; Mosley, Matthew C; Kurosu, Yuki; Smith Callahan, Laura A

2017-07-01

N-cadherin cell-cell signaling plays a key role in the structure and function of the nervous system. However, few studies have incorporated bioactive signaling from n-cadherin into tissue engineering matrices. The present study uses a continuous gradient approach in polyethylene glycol dimethacrylate hydrogels to identify concentration dependent effects of n-cadherin peptide, His-Ala-Val-Asp-Lle (HAVDI), on murine embryonic stem cell survival and neural differentiation. The n-cadherin peptide was found to affect the expression of pluripotency marker, alkaline phosphatase, in murine embryonic stem cells cultured on n-cadherin peptide containing hydrogels in a concentration dependent manner. Increasing n-cadherin peptide concentrations in the hydrogels elicited a biphasic response in neurite extension length and mRNA expression of neural differentiation marker, neuron-specific class III β-tubulin, in murine embryonic stem cells cultured on the hydrogels. High concentrations of n-cadherin peptide in the hydrogels were found to increase the expression of apoptotic marker, caspase 3/7, in murine embryonic stem cells compared to that of murine embryonic stem cell cultures on hydrogels containing lower concentrations of n-cadherin peptide. Increasing the n-cadherin peptide concentration in the hydrogels facilitated greater survival of murine embryonic stem cells exposed to increasing oxidative stress caused by hydrogen peroxide exposure. The combinatorial approach presented in this work demonstrates concentration dependent effects of n-cadherin signaling on mouse embryonic stem cell behavior, underscoring the need for the greater use of systematic approaches in tissue engineering matrix design in order to understand and optimize bioactive signaling in the matrix for tissue formation. Single cell encapsulation is common in tissue engineering matrices. This eliminates cellular access to cell-cell signaling. N-cadherin, a cell-cell signaling molecule, plays a vital role in the development of neural tissues, but has not been well studied as a bioactive signaling element in neural tissue engineering matrices. The present study uses a systematic continuous gradient approach to identify concentration dependent effects of n-cadherin derived peptide, HAVDI, on the survival and neural differentiation of murine embryonic stem cells. This work underscores the need for greater use to combinatorial strategies to understand the effect complex bioactive signaling, such as n-cadherin, and the need to optimize the concentration of such bioactive signaling within tissue engineering matrices for maximal cellular response. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The chemistry of dimethacrylate-styrene networks, and, Development of flame retardant, halogen-free fiber reinforced vinyl ester composites

NASA Astrophysics Data System (ADS)

Rosario, Astrid Christa

One of the major classes of polymer matrix resins under consideration for structural composite applications in the infrastructure and construction industries is vinyl ester resin. Vinyl ester resin is comprised of low molecular weight poly(hydroxyether) oligomers with methacrylate endgroups diluted with styrene monomer. The methacrylate endgroups cure with styrene via free radical copolymerization to yield thermoset networks. The copolymerization behavior of these networks was monitored by Fourier Transform Infrared Spectroscopy (FTIR) at various cure conditions. Reactions of the carbon-carbon double bonds of the methacrylate (943 cm-1) and styrene (910 cm-1 ) were followed independently. Oligomers possessing number average molecular weights of 700 g/mole were studied with systematically increasing levels of styrene. The Mortimer-Tidwell reactivity ratios indicated that at low conversion more styrene was incorporated into the network at lower cure temperatures. The experimental vinyl ester-styrene network compositions deviated significantly from those predicted by the Meyer-Lowry integrated copolymer equation at higher conversion, implying that the reactivity ratios for these networks may change with conversion. The kinetic data were used to provide additional insight into the physical and mechanical properties of these materials. In addition to establishing the copolymerization kinetics of these materials, the development of halogen free fiber reinforced vinyl ester composites exhibiting good flame properties was of interest. Flame retardant vinyl ester resins are used by many industries for applications requiring good thermal resistance. The current flame-retardant technology is dependent on brominated vinyl esters, which generate high levels of smoke and carbon monoxide. A series of halogen free binder systems has been developed and dispersed in the vinyl ester to improve flame retardance. The binder approach enables the vinyl ester resin to maintain its low temperature viscosity so that fabrication of composites via Vacuum Assisted Resin Transfer Molding (VARTM) is possible. The first binder system investigated was a polycaprolactone layered silicate nanocomposite, which was prepared via intercalative polymerization. Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) data indicated a mixed morphology of exfoliated and intercalated structures. The mechanical properties and the normalized peak heat release rates were comparable to the neat vinyl ester resin. Alternative binder systems possessing inherent flame retardance were also investigated. A series of binders comprised of novolac, bisphenol A diphosphate, and montmorillonite clay were developed and dispersed into the vinyl ester matrix. Cone calorimetry showed reductions in the peak heat release rate comparable to the brominated resin. Keywords: dimethacrylate; vinyl ester; network; reactivity ratios; nanocomposites; layered silicates; exfoliated; thermoset matrix resin; flame retardant

Laser acoustic emission thermal technique (LAETT): a technique for generating acoustic emission in dental composites.

PubMed

Duray, S J; Lee, S Y; Menis, D L; Gilbert, J L; Lautenschlager, E P; Greener, E H

1996-01-01

This study was designed to investigate a new method for generating interfacial debonding between the resin matrix and filler particles of dental composites. A pilot study was conducted to evaluate laser-induced acoustic emission in dental resins filled with varying quantities of particles. Model systems of 50/50 BisGMA/TEGDMA resin reinforced with 0, 25, and 75 wt% 5-10 micrometers silanated BaSiO(6) were analyzed. The sample size was 3.5 mm diameter x 0.25-0.28 mm thick. A continuous wave CO2 laser (Synrad Infrared Gas Laser Model 48-1) was used to heat the composite samples. Acoustic events were detected, recorded and processed by a model 4610 Smart Acoustic Monitor (SAM) with a 1220A preamp (Physical Acoustic Corp.) as a function of laser power. Initially, the acoustic signal from the model composites produced a burst pattern characteristic of fracturing, about 3.7 watts laser power. Acoustic emission increased with laser power up to about 6 watts. At laser powers above 6 watts, the acoustic emission remained constant. The amount of acoustic emission followed the trend: unfilled resin > composite with 25 wt% BaSiO(6) > composite with 75 wt% BaSiO(6). Acoustic emission generated by laser thermal heating is dependent on the weight percent of filler particles in the composite and the amount of laser power. For this reason, laser thermal acoustic emission might be useful as a nondestructive form of analysis of dental composites.

Multi-scale analysis of the effect of nano-filler particle diameter on the physical properties of CAD/CAM composite resin blocks.

PubMed

Yamaguchi, Satoshi; Inoue, Sayuri; Sakai, Takahiko; Abe, Tomohiro; Kitagawa, Haruaki; Imazato, Satoshi

2017-05-01

The objective of this study was to assess the effect of silica nano-filler particle diameters in a computer-aided design/manufacturing (CAD/CAM) composite resin (CR) block on physical properties at the multi-scale in silico. CAD/CAM CR blocks were modeled, consisting of silica nano-filler particles (20, 40, 60, 80, and 100 nm) and matrix (Bis-GMA/TEGDMA), with filler volume contents of 55.161%. Calculation of Young's moduli and Poisson's ratios for the block at macro-scale were analyzed by homogenization. Macro-scale CAD/CAM CR blocks (3 × 3 × 3 mm) were modeled and compressive strengths were defined when the fracture loads exceeded 6075 N. MPS values of the nano-scale models were compared by localization analysis. As the filler size decreased, Young's moduli and compressive strength increased, while Poisson's ratios and MPS decreased. All parameters were significantly correlated with the diameters of the filler particles (Pearson's correlation test, r = -0.949, 0.943, -0.951, 0.976, p < 0.05). The in silico multi-scale model established in this study demonstrates that the Young's moduli, Poisson's ratios, and compressive strengths of CAD/CAM CR blocks can be enhanced by loading silica nanofiller particles of smaller diameter. CAD/CAM CR blocks by using smaller silica nano-filler particles have a potential to increase fracture resistance.

Reinforcement of Dental Methacrylate with Glass Fiber after Heated Silane Application

PubMed Central

Fonseca, Rodrigo Borges; de Paula, Marcella Silva; Favarão, Isabella Negro; Kasuya, Amanda Vessoni Barbosa; de Almeida, Letícia Nunes; Mendes, Gustavo Adolfo Martins; Carlo, Hugo Lemes

2014-01-01

This study evaluated the influence of silane heat treatment and glass fiber fabrication type, industrially treated (I) or pure (P), on flexural and compressive strength of methacrylate resin bars (BISGMA/TEGDMA, 50/50%). Six groups (n = 10) were created: I-sil: I/silanated; P-sil: P-silanated; I-sil/heat: I/silanated heated to 100°; P-sil/heat: P/silanated heated to 100°; (I: I/not silanated; and P: P/not silanated. Specimens were prepared for flexural strength (10 × 2 × 1 mm) and for compressive strength 9.5 × 5.5 × 3 mm) and tested at 0.5 mm/min. Statistical analysis demonstrated the following for flexural strength (P < 0.05): I-sil: 155.89 ± 45.27BC; P-sil: 155.89 ± 45.27BC; I-sil/heat: 130.20 ± 22.11C; P-sil/heat: 169.86 ± 50.29AB; I: 131.87 ± 15.86C. For compressive strength, the following are demonstrated: I-sil: 1367.25 ± 188.77ab; P-sil: 867.61 ± 102.76d; I-sil/heat: 1162.98 ± 222.07c; P-sil/heat: 1499.35 ± 339.06a; and I: 1245.78 ± 211.16bc. Due to the impossibility of incorporating the stipulated amount of fiber, P group was excluded. Glass fiber treatment with heated silane enhanced flexural and compressive strength of a reinforced dental methacrylate. PMID:24967361

Physicochemical and bioactive properties of innovative resin-based materials containing functional halloysite-nanotubes fillers.

PubMed

Degrazia, Felipe Weidenbach; Leitune, Vicente Castelo Branco; Takimi, Antonio Shigueaki; Collares, Fabrício Mezzomo; Sauro, Salvatore

2016-09-01

This study aimed to assess the degree of conversion, microhardness, solvent degradation, contact angle, surface free energy and bioactivity (e.g., mineral precipitation) of experimental resin-based materials containing, pure or triclosan-encapsulated, aluminosilicate-(halloysite) nanotubes. An experimental resin blend was prepared using bis-GMA/TEGDMA, 75/25wt% (control). Halloysite nanotubes (HNT) doped with or without triclosan (TCN) were first analyzed using transmission electron microscopy (TEM). HNT or HNT/TCN fillers were incorporated into the resin blend at different concentrations (5, 10, and 20wt%). Seven experimental resins were created and the degree of conversion, microhardness, solvent degradation and contact angle were assessed. Bioactive mineral precipitation induced by the experimental resins was evaluated through Raman spectroscopy and SEM-EDX. TEM showed a clear presence of TCN particles inside the tubular lumen and along the outer surfaces of the halloysite nanotubes. The degree of conversion, surface free energy, microhardness, and mineral deposition of polymers increased with higher amount of HNTs. Conversely, the higher the amount (20wt%) of TCN-loaded HNTs the lower the microhardness of the experimental resins. The incorporation of pure or TCN-loaded aluminosilicate-(halloysite) nanotubes into resin-based materials increase the bioactivity of such experimental restorative materials and promotes mineral deposition. Therefore, innovative resin-based materials containing functional halloysite-nanotube fillers may represent a valuable alternative for therapeutic minimally invasive treatments. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Analysis of alternariol and alternariol monomethyl ether in foodstuffs by molecularly imprinted solid-phase extraction and ultra-high-performance liquid chromatography tandem mass spectrometry.

PubMed

Rico-Yuste, A; Walravens, J; Urraca, J L; Abou-Hany, R A G; Descalzo, A B; Orellana, G; Rychlik, M; De Saeger, S; Moreno-Bondi, M C

2018-03-15

Molecularly imprinted porous polymer microspheres selective to Alternaria mycotoxins, alternariol (AOH) and alternariol monomethyl ether (AME), were synthesized and applied to the extraction of both mycotoxins in food samples. The polymer was prepared using 4-vinylpiridine (VIPY) and methacrylamide (MAM) as functional monomers, ethylene glycol dimethacrylate (EDMA) as cross-linker and 3,8,9-trihydroxy-6H-dibenzo[b,d]pyran-6-one (S2) as AOH surrogate template. A molecularly imprinted solid phase extraction (MISPE) method has been optimized for the selective isolation of the mycotoxins from aqueous samples coupled to HPLC with fluorescence (λ ex =258nm; λ em =440nm) or MS/MS analysis. The MISPE method was validated by UPLC-MS/MS for the determination of AOH and AME in tomato juice and sesame oil based on the European Commission Decision 2002/657/EC. Method performance was satisfactory with recoveries from 92.5% to 106.2% and limits of quantification within the 1.1-2.8µgkg -1 range in both samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

New Elastomeric Materials Based on Natural Rubber Obtained by Electron Beam Irradiation for Food and Pharmaceutical Use

PubMed Central

Craciun, Gabriela; Manaila, Elena; Stelescu, Maria Daniela

2016-01-01

The efficiency of polyfunctional monomers as cross-linking co-agents on the chemical properties of natural rubber vulcanized by electron beam irradiation was studied. The following polyfunctional monomers were used: trimethylolpropane-trimethacrylate, zinc-diacrylate, ethylene glycol dimethacrylate, triallylcyanurate and triallylisocyanurate. The electron beam treatment was done using irradiation doses in the range of 75 kGy–300 kGy. The gel fraction, crosslink density and effects of different aqueous solutions, by absorption tests, have been investigated as a function of polyfunctional monomers type and absorbed dose. The samples gel fraction and crosslink density were determined on the basis of equilibrium solvent-swelling measurements by applying the modified Flory–Rehner equation for tetra functional networks. The absorption tests were done in accordance with the SR ISI 1817:2015 using distilled water, acetic acid (10%), sodium hydroxide (1%), ethylic alcohol (96%), physiological serum (sodium chloride 0.9%) and glucose (glucose monohydrate 10%). The samples structure and morphology were investigated by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy techniques. PMID:28774150

Unconstrained Recovery Characterization of Shape-Memory Polymer Networks for Cardiovascular Applications

PubMed Central

Yakacki, Christopher M.; Shandas, Robin; Lanning, Craig; Rech, Bryan; Eckstein, Alex; Gall, Ken

2009-01-01

Shape-memory materials have been proposed in biomedical device design due to their ability to facilitate minimally invasive surgery and recover to a predetermined shape in-vivo. Use of the shape-memory effect in polymers is proposed for cardiovascular stent interventions to reduce the catheter size for delivery and offer highly controlled and tailored deployment at body temperature. Shape-memory polymer networks were synthesized via photopolymerization of tert-butyl acrylate and poly (ethylene glycol) dimethacrylate to provide precise control over the thermomechanical response of the system. The free recovery response of the polymer stents at body temperature was studied as a function of glass transition temperature (Tg), crosslink density, geometrical perforation, and deformation temperature, all of which can be independently controlled. Room temperature storage of the stents was shown to be highly dependent on Tg and crosslink density. The pressurized response of the stents is also demonstrated to depend on crosslink density. This polymer system exhibits a wide range of shape-memory and thermomechanical responses to adapt and meet specific needs of minimally invasive cardiovascular devices. PMID:17296222

Magnetic molecularly imprinted polymer for the selective extraction of quercetagetin from Calendula officinalis extract.

PubMed

Ma, Run-Tian; Shi, Yan-Ping

2015-03-01

A new magnetic molecularly imprinted polymers (MMIPs) for quercetagetin was prepared by surface molecular imprinting method using super paramagnetic core-shell nanoparticle as the supporter. Acrylamide as the functional monomer, ethyleneglycol dimethacrylate as the crosslinker and acetonitrile as the porogen were applied in the preparation process. Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM) were applied to characterize the MMIPs, and High performance liquid chromatography (HPLC) was utilized to analyze the target analytes. The selectivity of quercetagetin MMIPs was evaluated according to their recognition to template and its analogues. Excellent binding for quercetagetin was observed in MMIPs adsorption experiment, and the adsorption isotherm models analysis showed that the homogeneous binding sites were distributed on the surface of the MMIPs. The MMIPs were employed as adsorbents in solid phase extraction for the determination of quercetagetin in Calendula officinalis extracts. Furthermore, this method is fast, simple and could fulfill the determination and extraction of quercetagetin from herbal extract. Copyright © 2014 Elsevier B.V. All rights reserved.

Additive Manufacturing of Catalytically Active Living Materials.

PubMed

Saha, Abhijit; Johnston, Trevor G; Shafranek, Ryan T; Goodman, Cassandra J; Zalatan, Jesse G; Storti, Duane W; Ganter, Mark A; Nelson, Alshakim

2018-04-25

Living materials, which are composites of living cells residing in a polymeric matrix, are designed to utilize the innate functionalities of the cells to address a broad range of applications such as fermentation and biosensing. Herein, we demonstrate the additive manufacturing of catalytically active living materials (AMCALM) for continuous fermentation. A multi-stimuli-responsive yeast-laden hydrogel ink, based on F127-dimethacrylate, was developed and printed using a direct-write 3D printer. The reversible stimuli-responsive behaviors of the polymer hydrogel inks to temperature and pressure are critical, as they enabled the facile incorporation of yeast cells and subsequent fabrication of 3D lattice constructs. Subsequent photo-cross-linking of the printed polymer hydrogel afforded a robust elastic material. These yeast-laden living materials were metabolically active in the fermentation of glucose into ethanol for 2 weeks in a continuous batch process without significant reduction in efficiency (∼90% yield of ethanol). This cell immobilization platform may potentially be applicable toward other genetically modified yeast strains to produce other high-value chemicals in a continuous biofermentation process.

New Elastomeric Materials Based on Natural Rubber Obtained by Electron Beam Irradiation for Food and Pharmaceutical Use.

PubMed

Craciun, Gabriela; Manaila, Elena; Stelescu, Maria Daniela

2016-12-21

The efficiency of polyfunctional monomers as cross-linking co-agents on the chemical properties of natural rubber vulcanized by electron beam irradiation was studied. The following polyfunctional monomers were used: trimethylolpropane-trimethacrylate, zinc-diacrylate, ethylene glycol dimethacrylate, triallylcyanurate and triallylisocyanurate. The electron beam treatment was done using irradiation doses in the range of 75 kGy-300 kGy. The gel fraction, crosslink density and effects of different aqueous solutions, by absorption tests, have been investigated as a function of polyfunctional monomers type and absorbed dose. The samples gel fraction and crosslink density were determined on the basis of equilibrium solvent-swelling measurements by applying the modified Flory-Rehner equation for tetra functional networks. The absorption tests were done in accordance with the SR ISI 1817:2015 using distilled water, acetic acid (10%), sodium hydroxide (1%), ethylic alcohol (96%), physiological serum (sodium chloride 0.9%) and glucose (glucose monohydrate 10%). The samples structure and morphology were investigated by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy techniques.

Fluorescence sensor for water in organic solvents prepared from covalent immobilization of 4-morpholinyl-1, 8-naphthalimide.

PubMed

Niu, Cheng-Gang; Qin, Pin-Zhu; Zeng, Guang-Ming; Gui, Xiao-Qin; Guan, Ai-Ling

2007-02-01

A new fluorescent dye, N-allyl-4-morpholinyl-1,8-naphthalimide (AMN), was synthesized as a fluorescence indicator in the fabrication of a sensor for determining water content in organic solvents. To prevent leakage of the fluorophore, AMN was photo-copolymerized with acrylamide, (2-hydroxyethyl)methacrylate, and triethylene glycol dimethacrylate on a glass surface treated with a silanizing agent. The sensing mechanism is based on the solvatochromic feature of the covalently immobilized AMN. The fluorescence intensity of AMN decreased with increasing water contents when it was excited at 400 nm. In the range of ca. 0.00-4.40% (v/v), the fluorescence intensity of AMN changed as a linear function of water content. The sensor exhibited satisfactory reproducibility, reversibility, and a response time (t (99)) of the order of 50 s. The detection limit was solvent-dependent, when acetonitrile was used as the solvent, and the detection limit could be as low as 0.006% (v/v) of water. Additionally, the prepared sensor is pH-insensitive and possesses a relatively long lifetime of at least one month.

Bioactive glass/polymer composite materials with mechanical properties matching those of cortical bone.

PubMed

Koleganova, Veronika A; Bernier, Suzanne M; Dixon, S Jeffrey; Rizkalla, Amin S

2006-06-01

Stress shielding resulting from mismatch in dynamic mechanical properties contributes to the reduced stability of osseous implants. Our objective was to develop biocompatible composites having mechanical properties similar to those of cortical bone. Polymers of urethane dimethacrylate (UDMA) and 2-hydroxyethyl methacrylate (HEMA, 0-20%) and composites containing bioactive glass particles (70% SiO(2), 25% CaO, and 5% P(2)O(5)), with or without silane treatment were prepared. Young's moduli of composites containing silane-treated glass (16 GPa) were significantly greater than those of composites containing untreated glass (12-13 GPa) or of unfilled polymers (5-6 GPa). Bioactive glass reduced water sorption by the composites and incorporation of silane-treated glass prevented HEMA-induced increases in water sorption. Osteoblast-like cells attached equally well to UDMA polymer and composite containing silane-treated bioactive glass. Thus, silane treatment improved the mechanical properties of bioactive glass composites without compromising biocompatibility. This material has a Young's modulus comparable to that of cortical bone. Therefore, silane-treated bioactive glass composites, when used as implant or cement materials, would reduce stress shielding and improve implant stability.

Inkjet printing of Chitlac-nanosilver--a method to create functional coatings for non-metallic bone implants.

PubMed

Nganga, Sara; Moritz, Niko; Kolakovic, Ruzica; Jakobsson, Kristina; Nyman, Johan O; Borgogna, Massimiliano; Travan, Andrea; Crosera, Matteo; Donati, Ivan; Vallittu, Pekka K; Sandler, Niklas

2014-10-22

Biostable fiber-reinforced composites, based on bisphenol-A-dimethacrylate and triethyleneglycoldimethacrylate thermoset polymer matrix reinforced with E-glass fibers have been successfully used in cranial reconstructions and the material has been approved for clinical use. As a further refinement of these implants, antimicrobial, non-cytotoxic coatings on the composites were created by an immersion procedure driven by strong electrostatic interactions. Silver nanoparticles (nAg) were immobilized in lactose-modified chitosan (Chitlac) to prepare the bacteriostatic coatings. Herein, we report the use of inkjet technology (a drop-on-demand inkjet printer) to deposit functional Chitlac-nAg coatings on the thermoset substrates. Characterization methods included scanning electron microscopy, scanning white light interferometry and electro-thermal atomic absorption spectroscopy. Inkjet printing enabled the fast and flexible functionalization of the thermoset surfaces with controlled coating patterns. The coatings were not impaired by the printing process: the kinetics of silver release from the coatings created by inkjet printing and conventional immersion technique was similar. Further research is foreseen to optimize printing parameters and to tailor the characteristics of the coatings for specific clinical applications.

Enrichment of Glycoproteins using Nano-scale Chelating Con A Monolithic Capillary Chromatography

PubMed Central

Feng, Shun; Yang, Na; Pennathur, Subramaniam; Goodison, Steve; Lubman, David M.

2009-01-01

Immobilized lectin chromatography can be employed for glycoprotein enrichment, but commonly used columns have limitations of yield and resolution. In order to improve efficiency and to make the technique applicable to minimal sample material, we have developed a nano-scale chelating Concanavalin A (Con A) monolithic capillary prepared using GMA-EDMA (glycidyl methacrylate–co-ethylene dimethacrylate) as polymeric support. Con A was immobilized on Cu(II)-charged iminodiacetic acid (IDA) regenerable sorbents by forming a IDA:Cu(II):Con A sandwich affinity structure that has high column capacity as well as stability. When compared with conventional Con A lectin chromatography, the monolithic capillary enabled the better reproducible detection of over double the number of unique N-glycoproteins in human urine samples. Utility for analysis of minimal biological samples was confirmed by the successful elucidation of glycoprotein profiles in mouse urine samples at the microliter scale. The improved efficiency of the nano-scale monolithic capillary will impact the analysis of glycoproteins in complex biological samples, especially where only limited material may be available. PMID:19366252

On-chip sample pretreatment using a porous polymer monolithic column for solid-phase microextraction and chemiluminescence determination of catechins in green tea.

PubMed

Lin, Ling; Chen, Hui; Wei, Huibin; Wang, Feng; Lin, Jin-Ming

2011-10-21

A porous polymer monolithic column for solid-phase microextraction and chemiluminescence detection was integrated into a simple microfluidic chip for the extraction and determination of catechins in green tea. The porous polymer was prepared by poly(glycidyl methacrylate-co-ethylene dimethacrylate) and modified with ethylenediamine. Catechins can be concentrated in the porous polymer monolithic column and react with potassium permanganate to give chemiluminescence. The microfluidic chip is reusable with high sensitivity and very low reagent consumption. The on-line preconcentration and detection can be realized without an elution step. The enrichment factor was calculated to be about 20 for catechins. The relative chemiluminescence intensity increased linearly with concentration of catechin from 5.0 × 10(-9) to 1.0 × 10(-6) M and the limit of detection was 1.0 × 10(-9) M. The proposed method was applied to determine catechin in green tea. The recoveries are from 90% to 110% which benefits the actual application for green tea samples.

Estrogenicity of resin-based composites and sealants used in dentistry.

PubMed Central

Olea, N; Pulgar, R; Pérez, P; Olea-Serrano, F; Rivas, A; Novillo-Fertrell, A; Pedraza, V; Soto, A M; Sonnenschein, C

1996-01-01

We tested some resin-based composites used in dentistry for their estrogenic activity. A sealant based on bisphenol-A diglycidylether methacrylate (bis-GMA) increased cell yields, progesterone receptor expression, and pS2 secretion in human estrogen-target, serum-sensitive MCF7 breast cancer cells. Estrogenicity was due to bisphenol-A and bisphenol-A dimethacrylate, monomers found in the base paste of the dental sealant and identified by mass spectrometry. Samples of saliva from 18 subjects treated with 50 mg of a bis-GMA-based sealant applied on their molars were collected 1 hr before and after treatment. Bisphenol-A (range 90-931 micrograms) was identified only in saliva collected during a 1-hr period after treatment. The use of bis-GMA-based resins in dentistry, and particularly the use of sealants in children, appears to contribute to human exposure to xenoestrogens. Images Figure 1. A Figure 1. B Figure 2. Figure 3. A Figure 3. B Figure 4. A Figure 4. B Figure 5. A Figure 5. B Figure 6. A Figure 6. B Figure 7. A Figure 7. B Figure 8. Figure 9. Figure 10. PMID:8919768

Determination of residual monomers resulting from the chemical polymerization process of dental materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boboia, S.; Moldovan, M.; Ardelean, I.

The residual monomer present in post-polymerized dental materials encourages premature degradation of the reconstructed tooth. That is why the residual monomer should be quantified in a simple, fast, accurate and reproducible manner. In our work we propose such an approach for accurate determination of the residual monomer in dental materials which is based on low-field nuclear magnetic resonance (NMR) relaxometry. The results of the NMR approach are compared with those of the high performance liquid chromatography (HPLC) technique. The samples under study contain the main monomers (2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane and triethylene glycol dimethacrylate) constituting the liquid phase of most dental materials andmore » an initiator. Two samples were analyzed with different ratios of chemical initiation systems: N,N-dimethyl-p-toluide: benzoyl peroxide (1:2 and 0.7:1.2). The results obtained by both techniques highlight that by reducing the initiator the polymerization process slows down and the amount of residual monomer reduces. This prevents the premature degradation of the dental fillings and consequently the reduction of the biomaterial resistance.« less

Bioprinting 3D cell-laden hydrogel microarray for screening human periodontal ligament stem cell response to extracellular matrix.

PubMed

Ma, Yufei; Ji, Yuan; Huang, Guoyou; Ling, Kai; Zhang, Xiaohui; Xu, Feng

2015-12-22

Periodontitis is an inflammatory disease negatively affecting up to 15% of adults worldwide. Periodontal ligament stem cells (PDLSCs) hold great promises for periodontal tissue regeneration, where it is necessary to find proper extracellular matrix (ECM) materials (e.g., composition, concentration). In this study, we proposed a bioprinting-based approach to generate nano-liter sized three-dimensional (3D) cell-laden hydrogel array with gradient of ECM components, through controlling the volume ratio of two hydrogels, such as gelatin methacrylate (GelMA) and poly(ethylene glycol) (PEG) dimethacrylate. The resulting cell-laden array with a gradient of GelMA/PEG composition was used to screen human PDLSC response to ECM. The behavior (e.g., cell viability, spreading) of human PDLSCs in GelMA/PEG array were found to be depended on the volume ratios of GelMA/PEG, with cell viability and spreading area decreased along with increasing the ratio of PEG. The developed approach would be useful for screening cell-biomaterial interaction in 3D and promoting regeneration of functional tissue.

The effect of EGDMA on tensile and thermal properties of irradiated low density polyethylene/sepiolite nanocomposites

NASA Astrophysics Data System (ADS)

Ghazali, Siti Nadia Aini; Mohamad, Zurina; Majid, Rohah A.; Appadu, Sivanesan

2017-07-01

This study presents the influence of ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent through electron beam crosslinking process. Therefore, the effects of EGDMA on irradiated low density polyethylene/sepiolite (LDPE/SEP) nanocomposites on the tensile and thermal properties at 4 part per hundred resin (phr) sepiolite were investigated. The LDPE/SEP nanocomposites were prepared by melt mixing using twin screw extruder at 160 ˚C with a screw speed of 50 rpm. The nanocomposites were then undergone injection moulding process followed by irradiated using 2 MeV electron beam machine at doses ranging from 0 to 200 kGy in the air at ambient temperature. It was found that the tensile strength and Young's modulus were slightly increased with the presence of co-agent. The sample containing 4 phr sepiolite at 200 kGy showed 9% increase in tensile strength when EGDMA was added. However, the result of thermogravimetry analysis (TGA) showed some reduction in thermal stability of nanocomposites on 100 kGy irradiation dose. EGDMA had reduced the optimum irradiation dose without having any adverse effect on tensile and thermal properties.

Newly designed silver coated-magnetic, monodisperse polymeric microbeads as SERS substrate for low-level detection of amoxicillin

NASA Astrophysics Data System (ADS)

Kibar, Güneş; Topal, Ahmet Emin; Dana, Aykutlu; Tuncel, Ali

2016-09-01

We report the preparation of silver-coated magnetic polymethacrylate core-shell nanoparticles for use in surface-enhanced Raman scattering based drug detection. Monodisperse porous poly (mono-2-(methacryloyloxy)ethyl succinate-co-glycerol dimethacrylate), poly (MMES-co-GDMA) microbeads of ca. 5 μm diameter were first synthesized through a multistage microsuspension polymerization technique to serve as a carboxyl-bearing core region. Microspheres were subsequently magnetized by the co-precipitation of ferric ions, aminated through the surface hydroxyl groups and decorated with Au nanoparticles via electrostatic attraction. An Ag shell was then formed on top of the Au layer through a seed-mediated growth process, resulting in micron-sized monodisperse microbeads that exhibit Raman enhancement effects due to the roughness of the Ag surface layer. The core-shell microspheres were used as a new substrate for the detection of amoxicillin at trace concentrations up to 10-8 M by SERS. The proposed SERS platform can be evaluated as a useful tool for the follow-up amoxicillin pollution and low-level detection of amoxicillin in aqueous media.

Molecularly imprinted polymer for selective extraction of malachite green from seawater and seafood coupled with high-performance liquid chromatographic determination.

PubMed

Lian, Ziru; Wang, Jiangtao

2012-12-01

In this paper, a highly selective sample cleanup procedure combining molecular imprinting technique (MIT) and solid-phase extraction (SPE) was developed for the isolation of malachite green in seawater and seafood samples. The molecularly imprinted polymer (MIP) was prepared using malachite green as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The imprinted polymer and non-imprinted polymer were characterized by scanning electron microscope and static adsorption experiments. The MIP showed a high adsorption capacity and was used as selective sorbent for the SPE of malachite green. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chromatography with diodearray detection for the analysis of malachite green in seawater and seafood samples was also established. Finally, five samples were determined. The results showed that malachite green concentration in one seawater sample was at 1.30 μg L⁻¹ and the RSD (n=3) was 4.15%. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Kinetics study of invertase covalently linked to a new functional nanogel.

PubMed

Raj, Lok; Chauhan, Ghanshyam S; Azmi, Wamik; Ahn, J-H; Manuel, James

2011-02-01

Nanogels are promising materials as supports for enzyme immobilization. A new hydrogel comprising of methacrylic acid (MAAc) and N-vinyl pyrrolidone (N-VP) and ethyleneglycol dimethacrylate (EGDMA) was synthesized and converted to nanogel by an emulsification method. Nanogel was further functionalized by Curtius azide reaction for use as support for the covalent immobilization of invertase (Saccharomyces cerevisiae). As-prepared or invertase-immobilized nanogel was characterized by FTIR, XRD, TEM and nitrogen analysis. The characterization of both free and the immobilized-invertase were performed using a spectrophotometric method at 540 nm. The values of V(max), maximum reaction rate, (0.123 unit/mg), k(m), Michaelis constant (7.429 mol/L) and E(a), energy of activation (3.511 kj/mol) for the immobilized-invertase are comparable with those of the free invertase at optimum conditions (time 70 min, pH 6.0 and temperature 45°C). The covalent immobilization enhanced the pH and thermal stability of invertase. The immobilized biocatalyst was efficiently reused up to eight cycles. Copyright © 2010 Elsevier Ltd. All rights reserved.

Analysis of residual monomers in dendritic methacrylate copolymers and composites by HPLC and headspace-GC/MS.

PubMed

Viljanen, Eeva K; Langer, Sarka; Skrifvars, Mikael; Vallittu, Pekka K

2006-09-01

The aim of this study was to analyze the residual monomer content of photopolymerized dendritic methacrylate copolymers and particulate filler composites. Headspace-gas chromatography/mass spectrometry (HS-GC/MS) was compared with high performance liquid chromatography (HPLC). The resin mixtures consisted of a dendritic methacrylate monomer, methyl methacrylate and acetoacetoxyethyl methacrylate in varied proportions. In addition, one of the composites contained 1,4-butanediol dimethacrylate. Camphorquinone and 2-(N,N-dimethylamino)ethyl methacrylate were used as the light-activated initiator system. The content of residual methyl methacrylate and acetoacetoxyethyl methacrylate after 40 s photopolymerization were analyzed with HPLC and HS-GC/MS. The content of residual methyl methacrylate decreased and residual acetoacetoxyethyl methacrylate increased with increasing concentration of acetoacetoxyethyl methacrylate in the resin mixture. The results with both methods had the same trend. The addition of acetoacetoxyethyl methacrylate enhanced the copolymerization of methyl methacrylate, but did not decrease the total residual monomer content. The HS-GC/MS method was found to be a feasible method in the analysis of low-boiling residuals in dental polymers.

Synthesis of surface molecular imprinted polymers based on carboxyl-modified silica nanoparticles with the selective detection of dibutyl phthalate from tap water samples

NASA Astrophysics Data System (ADS)

Xu, Wanzhen; Zhang, Xiaoming; Huang, Weihong; Luan, Yu; Yang, Yanfei; Zhu, Maiyong; Yang, Wenming

2017-12-01

In this work, the molecular imprinted polymers were synthesized with the low monomer concentrations for dibutyl phthalate (DBP). The polymers were prepared over carboxyl-modified silica nanoparticle, which used methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker agent and azoisobutyronitrile as the initiator in the process of preparation. Various measures were used to characterize the structure and morphology in order to get the optimal polymer. The characterization results show that the optimal polymer has suitable features for further adsorption process. And adsorption capacity experiments were evaluated to analyze its adsorption performance, through adsorption isotherms/kinetics, selectivity adsorption and desorption and regeneration experiments. These results showed that the molecular imprinted polymers had a short equilibrium time about 60 min and high stability with 88% after six cycles. Furthermore, the molecular imprinted polymers were successfully applied to remove dibutyl phthalate. The concentration range was 5.0-30.0 μmol L-1, and the limit of detection was 0.06 μmol L-1 in tap water samples.

Study on the molecularly imprinted polymers with methyl-testosterone as the template.

PubMed

Yang, Minli; Gu, Wancheng; Sun, Li; Zhang, Feng; Ling, Yun; Chu, Xiaogang; Wang, Daning

2010-04-15

Molecularly imprinted polymers (MIPs) using methyl-testosterone as the template, methacrylic acid (MAA) as the monomer and ethylene glycol dimethacrylate (EDMA) as the crosslinker were prepared by precipitation polymerization. The morphology of the obtained particles was characterized by scanning electron microscopy (SEM) and the pore size was measured by BET. Then, the specificity and selectivity of the MIPs were evaluated using the equilibrium rebinding experiments. Besides, the MIPs were also used as the stationary phase of HPLC column and the retention behaviour to the template and analogues was confirmed using HPLC-MS-MS. Finally, the real application of the methyl-testosterone imprinted polymers was evaluated using SPE procedure with the spiked tap water and lake water. The results indicated that the prepared methyl-testosterone imprinted polymer showed specific rebinding ability to its template and could retain the template strongly compared with other structural analogues. At the same time, the MIPs could be used as SPE column to enrich methyl-testosterone in the lake water and show broad prospects in real samples. (c) 2009 Elsevier B.V. All rights reserved.

Preparation and adsorption behavior of berberine hydrochloride imprinted polymers by using silica gel as sacrificed support material

NASA Astrophysics Data System (ADS)

Li, Hui; Li, Yuzhuo; Li, Zhiping; Peng, Xiyang; Li, Yanan; Li, Gui; Tan, Xianzhou; Chen, Gongxi

2012-03-01

Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2 μmol g-1 and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

Cyclodextrin modified hydrogels of PVP/PEG for sustained drug release.

PubMed

Nielsen, Anne Louise; Madsen, Flemming; Larsen, Kim Lambertsen

2009-02-01

Hydrogels are water swollen networks of polymers and especially hydrogels consisting of poly vinylpyrrolidone/poly ethyleneglycol-dimethacrylate (PVP/PEG-DMA) blends show promising wound care properties. Enhanced functionality of the hydrogels can be achieved by incorporating drugs and other substances that may assist wound healing into the gel matrix. Controlling the release of active compounds from the hydrogels may be possible by carefully modifying the polymer matrix. For this purpose, cyclodextrins (CD) were grafted to the polymer matrix in 4-5 w/w% in an attempt to retard the release of water-soluble drugs. Ibuprofenate (IBU) was chosen as model drug and loaded in IBU/CD ratios of 0.6, 1.2, and 2.5. Vinyl derivatives of alpha-, beta- and gamma-CD were produced, added to the prepolymer blend and cured by UV-light. During this curing process the CD derivatives were covalently incorporated into the hydrogel matrix. The modified hydrogels were loaded with ibuprofenate by swelling. The release of the model drug from CD modified hydrogels show that especially covalently bonded beta-cyclodextrin can change both the release rate and the release profile of ibuprofen.

Efficiency of solution-processed multilayer polymer light-emitting diodes using charge blocking layers

NASA Astrophysics Data System (ADS)

Kasparek, Christian; Rörich, Irina; Blom, Paul W. M.; Wetzelaer, Gert-Jan A. H.

2018-01-01

By blending semiconducting polymers with the cross-linkable matrix ethoxylated-(4)-bisphenol-a-dimethacrylate (SR540), an insoluble layer is acquired after UV-illumination. Following this approach, a trilayer polymer light-emitting diode (PLED) consisting of a blend of poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (poly-TPD) and SR540 as an electron-blocking layer, Super Yellow-Poly(p-phenylene vinylene) (SY-PPV) blended with SR540 as an emissive layer, and poly(9,9-di-n-octylfluorenyl-2,7-diyl) as a hole-blocking layer is fabricated from solution. The trilayer PLED shows a 23% increase in efficiency at low voltage as compared to a single layer SY-PPV PLED. However, at higher voltage, the advantage in current efficiency gradually decreases. A combined experimental and modelling study shows that the increased efficiency is not only due to the elimination of exciton quenching at the electrodes but also due to suppressed nonradiative trap-assisted recombination due to carrier confinement. At high voltages, holes can overcome the hole-blocking barrier, which explains the efficiency roll-off.

Molecularly imprinted hydrogels as functional active packaging materials.

PubMed

Benito-Peña, Elena; González-Vallejo, Victoria; Rico-Yuste, Alberto; Barbosa-Pereira, Letricia; Cruz, José Manuel; Bilbao, Ainhoa; Alvarez-Lorenzo, Carmen; Moreno-Bondi, María Cruz

2016-01-01

This paper describes the synthesis of novel molecularly imprinted hydrogels (MIHs) for the natural antioxidant ferulic acid (FA), and their application as packaging materials to prevent lipid oxidation of butter. A library of MIHs was synthesized using a synthetic surrogate of FA, 3-(4-hydroxy-3-methoxyphenyl)propionic acid (HFA), as template molecule, ethyleneglycol dimethacrylate (EDMA) as cross-linker, and 1-allylpiperazine (1-ALPP) or 2-(dimethylamino)ethyl methacrylate (DMAEMA), in combination with 2-hydroxyethyl methacrylate (HEMA) as functional monomers, at different molar concentrations. The DMAEMA/HEMA-based MIHs showed the greatest FA loading capacity, while the 1-ALLP/HEMA-based polymers exhibited the highest imprinting effect. During cold storage, FA-loaded MIHs protected butter from oxidation and led to TBARs values that were approximately half those of butter stored without protection and 25% less than those recorded for butter covered with hydrogels without FA, potentially extending the shelf life of butter. Active packaging is a new field of application for MIHs with great potential in the food industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

Polymeric monolith column composited with multiwalled carbon nanotubes-β-cyclodextrin for the selective extraction of psoralen and isopsoralen.

PubMed

Ling, Xu; Zou, Li; Chen, Zilin

2017-09-01

A polymeric column that contains multiwalled carbon nanotubes-β-cyclodextrin composite was developed. The composite was wrapped into the poly(butyl methacrylate-ethylene dimethacrylate) monolith column (0.76 mm id and 10 cm in length). The column was then applied for the online solid-phase microextraction of psoralen and isopsoralen from Fructus Psoraleae. Following microextraction, the coumarins were quantified by high-performance liquid chromatography with C 18 separation column and UV detection. The effects of sample flow rate, sample volume, and pH value were optimized. The method showed low limits of detection (20 pg/mL, S/N = 3) for both psoralen and isopsoralen. Finally the method was successfully applied to the determination of psoralen and isopsoralen in spiked herb extracts and rat plasma where it gave recoveries that ranged between 93.2 and 102.1%. The empty hydrophobic cavities of β-cyclodextrin and the hydrophobicity of multiwalled carbon nanotubes provided specific extraction capability for psoralen and isopsoralen. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of phenformin hydrochloride using molecular imprinting technology coupled with flow-injection chemiluminescence.

PubMed

Liu, Zhenbo; Jia, Fengyan; Wang, Wenwen; Wang, Cuixia; Liu, Yongming

2012-01-01

A novel method was developed using molecular imprinting technology (MIT) coupled with flow-injection chemiluminescence (FI-CL) for highly sensitive detection of phenformin hydrochloride (PH). The phenformin imprinted polymer was synthesized with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. Newly synthesized molecularly imprinted polymer (MIP) particles were packed into a column as a selective recognition element for determination of PH. A CL method for the determination of PH was developed based on the CL reaction of PH with N-bromosuccinimide sensitized by eosin Y in basic media. The optimization of detection conditions was investigated. The CL intensity responded linearly to the concentration of PH in the range 0.09-2.0 µg/mL, with a correlation coefficient of 0.9920. The detection limit was 0.031 µg/mL. The relative standard deviation for the determination of 1.0 µg/mL PH solution was 1.0% (n = 11). The method was applied to the determination of PH in urine samples, with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.

Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of zinc ions.

PubMed

Roushani, Mahmoud; Abbasi, Shahryar; Khani, Hossein; Sahraei, Reza

2015-04-15

A new Zinc (II) ion-imprinted polymer (IIPs) nanoparticles was synthesised for the separation and recovery of trace Zn (II) ion from food and water sample. Zn (II) IIP was prepared by copolymerisation of methyl methacrylate (monomer) and ethylene glycol dimethacrylate (cross-linker) in the presence of Zn (II)-N,N'-o-phenylene bis (salicylideneimine) ternary complex wherein Zn (II) ion is the imprint ion and is used to form the imprinted polymer. Moreover, control polymer (NIP) particles were similarly prepared without the zinc (II) ions. The unleached and leached IIP particles were characterised by X-ray diffraction, Fourier transform infra-red spectroscopy and scanning electron microscopy. The preconcentration of Zn(2+) from aqueous solution was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the uptake and desorption times, the aqueous phase and the desorption volumes. Flame atomic absorption spectrometry was employed for determination of zinc in aqueous solution. Copyright © 2014 Elsevier Ltd. All rights reserved.

A comparative evaluation of polymerization stress data obtained with four different mechanical testing systems.

PubMed

Gonçalves, Flávia; Boaro, Leticia C; Ferracane, Jack L; Braga, Roberto R

2012-06-01

The null hypothesis was that mechanical testing systems used to determine polymerization stress (σ(pol)) would rank a series of composites similarly. Two series of composites were tested in the following systems: universal testing machine (UTM) using glass rods as bonding substrate, UTM/acrylic rods, "low compliance device", and single cantilever device ("Bioman"). One series had five experimental composites containing BisGMA:TEGDMA in equimolar concentrations and 60, 65, 70, 75 or 80 wt% of filler. The other series had five commercial composites: Filtek Z250 (3M ESPE), Filtek A110 (3M ESPE), Tetric Ceram (Ivoclar), Heliomolar (Ivoclar) and Point 4 (Kerr). Specimen geometry, dimensions and curing conditions were similar in all systems. σ(pol) was monitored for 10 min. Volumetric shrinkage (VS) was measured in a mercury dilatometer and elastic modulus (E) was determined by three-point bending. Shrinkage rate was used as a measure of reaction kinetics. ANOVA/Tukey test was performed for each variable, separately for each series. For the experimental composites, σ(pol) decreased with filler content in all systems, following the variation in VS. For commercial materials, σ(pol) did not vary in the UTM/acrylic system and showed very few similarities in rankings in the others tests system. Also, no clear relationships were observed between σ(pol) and VS or E. The testing systems showed a good agreement for the experimental composites, but very few similarities for the commercial composites. Therefore, comparison of polymerization stress results from different devices must be done carefully. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Dynamic mechanical thermal analysis of composite resins with CQ and PPD as photo-initiators photoactivated by QTH and LED units.

PubMed

Brandt, William Cunha; Silva, Cristina Gomes; Frollini, Elisabete; Souza-Junior, Eduardo Jose Carvalho; Sinhoreti, Mário Alexandre Coelho

2013-08-01

The aim of this study was to evaluate the thermal and mechanical properties of the composite resins containing the photo-initiators camphorquinone (CQ) and/or phenyl-propanodione (PPD) when photoactivated with halogen lamp (XL2500/3M-ESPE), monowave (UltraBlueIS/DMC) and polywave (UltraLume5/Ultradent) LED units. A blend of BisGMA, UDMA, BisEMA and TEGDMA was prepared with the same wt% of photo-initiators CQ and/or PPD and 65wt% of silaneted filler particles. Compression strength (CS), diametral tensile strength (DTS) and diametral modulus (DM) were tested. Thermogravimetric analysis (TGA) was made and the lost residual monomer were verified. Dynamic mechanical thermal analysis (DMTA) was used for to analyze the glass transition temperature (Tg) and the storage modulus in 37°C. Degree of conversion (DC) was accomplished in the same samples of DMA using middle-infrared spectroscopy (mid-IR). CQ, CQ/PPD and PPD obtained the same results for all mechanical properties (CS, DTS and DM), lost residual monomer and storage modulus in 37°C, regardless LCU used. The results of Tg showed that the combination PPD-UltraLume5 produced the highest values. DC showed that the combination CQ-UltraLume5 resulted in the highest values and PPD-XL2500 in the lowest DC values. The study shows that PPD is not only effective photosensitizers, but also photocrosslinking agents for dental composite resins with a similar efficiency to CQ. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis and characterization of novel halloysite-incorporated adhesive resins.

PubMed

Feitosa, Sabrina A; Münchow, Eliseu A; Al-Zain, Afnan O; Kamocki, Krzysztof; Platt, Jeffrey A; Bottino, Marco C

2015-11-01

To investigate the effects of Halloysite® aluminosilicate clay nanotubes (HNTs) addition on selected physical, mechanical, and biological properties of experimental adhesive resins. Experimental dentin adhesive resins were prepared by mixing Bis-GMA, TEGDMA, HEMA (50/25/25wt.%), and photo-initiators. As-received HNTs were then incorporated into the resin mixture at distinct concentrations: 0 (HNT-free, control), 1, 2.5, 5, 7.5, 10, and 20wt.%. The degree of conversion (DC), radiopacity (RP), Knoop hardness (KHN), flexural strength (FS), and cytotoxicity analyses were carried out for each adhesive formulation. The adhesive resin of Adper Scotchbond Multi-Purpose (SBMP) was used as the commercially available reference for both the RP and cytotoxicity tests. Data were statistically analyzed using One-Way ANOVA and Tukey's test (p≤0.05). All adhesives exhibited similar DC (p=0.1931). The RP of adhesives was improved with the addition of up to 5wt.% of HNTs (p<0.001). Adhesives containing 5-10wt.% of HNTs led to greater KHN when compared to the control (p<0.001). The FS was reduced only when 20wt.% of HNTs was added (p≤0.001). None of the prepared adhesives was cytotoxic. The incorporation of up to 10wt.% of HNTs into the adhesive resins did not jeopardize the tested physical and biological properties. When using HNTs as carriers of drugs/bioactive compounds, the amount of the former added into adhesive resin materials should not exceed 10wt.%; otherwise, a significant reduction in physicomechanical properties may be expected. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of (monomer - crosslinker – initiator) composition during non imprinted polymers synthesis for catechin retention

NASA Astrophysics Data System (ADS)

Triadhi, U.; Zulfikar, M. A.; Setiyanto, H.; Amran, M. B.

2018-05-01

MISPE (molecularly imprinted Solid Phase Extraction) is a separation technique using a solid adsorbent as a principle of MI (molecularly imprinted). Methacrylic acid (MAA) was used as a monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, benzoyl peroxide (BPO) as an initiator and acetonitrile (ACN) as a porogen. Catechin will be used as the template. Thermal and microwave methods were employed in the synthesis method. When analyzed using FTIR spectra, it was found that there were no significant differences between NIP (non-imprinted polymer) resulting from thermal method and that resulting from microwave method. Preparation of polymers by microwave method required 4 mins at 60-65 °C, significantly less than thermal method, that took 60 minutes at the same temperature. The variations of mole ratios of the monomer, the crosslinker, and the initiator were also performed. Based on the FTIR spectra, intensity of some peaks were changed due to the decreases of concentration. The optimum composition for NIP synthesis was MAA: EGDMA: BPO ratio of 5:30:0.5 (in mmole). The TGA curve showed that the NIP sythesized using microwave method experienced mass loss of around 98.50% at 604.8 °C.

Development of a γ-alumina- nanoparticle-functionalized porous polymer monolith for the enrichment of Sudan dyes in red wine samples.

PubMed

Li, Wanjun; Zhou, Xiao; Ye, Juanjuan; Jia, Qiong

2013-10-01

Monolithic materials were synthesized in capillaries by in situ polymerization with N-isopropylacrylamide, glycidyl methacrylate, and ethylene dimethacrylate as the monomers, and methanol and PEG as the porogens. With γ-alumina nanoparticles attached to the surface of the porous monolithic column via epoxide groups, a novel polymer monolith microextraction (PMME) material was prepared with a good mechanical stability and a high extraction capacity. SEM and X-ray photoelectron spectroscopy were employed to characterize the modified monolithic column, demonstrating that γ-alumina nanoparticles were effectively functionalized onto the monolithic column. In addition, a new method was developed for the analysis of Sudan I-IV dyes using PMME coupled with HPLC. In order to obtain the optimum extraction efficiency, the PMME conditions including desorption solvent type, sample pH, sample volume, sample flow rate, and eluent flow rate were investigated. Under the optimum conditions, we obtained acceptable linearities, low LODs, and good intra- and interday RDSs. When applied to the determination of Sudan I-IV dyes in red wine samples, satisfactory recoveries were obtained in the range of 84.0-115.9%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecularly imprinted solid-phase extraction combined with high performance liquid chromatography for analysis of phenolic compounds from environmental water samples.

PubMed

Feng, Qin-Zhong; Zhao, Li-Xia; Yan, Wei; Lin, Jin-Ming; Zheng, Zhi-Xia

2009-08-15

The molecularly imprinted bulk polymer with 2,4,6-trichlorophenol (2,4,6-TCP) as the template molecule and methylacrylic acid (MAA), ethylene glycol dimethacrylate (EGDMA) as functional monomer and the crosslinker, respectively, has been prepared and applied to the molecularly imprinted solid-phase extraction (MISPE) procedure for selective preconcentration of phenolic compounds from environmental water samples. Various parameters affecting the extraction efficiency of the polymer have been evaluated to optimize the selective preconcentration of the phenolic compounds from aqueous samples. The characteristics of the MISPE method were validated by HPLC. The recoveries ranged between 90% and 98% (RSD: 0.9-2.3%, n=3) for tap water, between 85% and 105% (RSD: 2.6-4.9%, n=3) for river water, between 78% and 98% (RSD: 2.6-5.4%, n=3) for sewage water fortified with 0.4 mg L(-1) of phenol, 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), pentachlorophenol (PCP). It was demonstrated that this MISPE-HPLC method could be applied to direct preconcentration and determination of phenolic compounds in environmental water samples.

Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of mercury in water and food samples employing cold vapor atomic absorption spectrometry.

PubMed

Roushani, Mahmoud; Abbasi, Shahryar; Khani, Hossein

2015-09-01

We describe a nanosized Hg(II)-imprinted polymer that was prepared from methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as cross-linker, 2,2'-azobisisobutyronitrile (AIBN) as radical initiator, 2, 2'-di pyrydyl amine as a specific ligand, and Hg (II) as the template ions by precipitation polymerization method in methanol as the progeny solvent. Batch adsorption experiments were carried out as a function of pH, Hg (II) imprinted polymer amount, adsorption and desorption time, volume, and concentration of eluent. The synthesized polymer particles were characterized physically and morphologically by using infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopic techniques. The maximum adsorption capacity of the ion-imprinted and non-imprinted sorbent was 27.96 and 7.89 mg g(-1), respectively. Under optimal conditions, the detection limit for mercury was 0.01 μg L(-1) and the relative standard deviation was 3.2 % (n = 6) at the 1.00 μg L(-1). The procedure was applied to determination of mercury in fish and water samples with satisfactory results.

Superparamagnetic polymer emulsion particles from a soap-free seeded emulsion polymerization and their application for lipase immobilization.

PubMed

Cui, Yanjun; Chen, Xia; Li, Yanfeng; Liu, Xiao; Lei, Lin; Zhang, Yakui; Qian, Jiayu

2014-01-01

Using emulsion copolymer of styrene (St), glycidyl methacrylate (GMA) and 2-hydroxyethyl methacrylate (HEMA) as seed latexes, the superparamagnetic polymer emulsion particles were prepared by seeded emulsion copolymerization of butyl methacrylate (BMA), vinyl acetate (VAc) and ethylene glycol dimethacrylate in the presence of the seed latexes and superparamagnetic Fe3O4/SiOx nanoparticles (or Fe3O4-APTS nanoparticles) through a two-step process, without addition of any emulsifier. The magnetic emulsion particles named P(St-GMA-HEMA)/P(BMA-VAc) were characterized by transmission electron microscope and vibrating sample magnetometry. The results showed that the magnetic emulsion particles held a structure with a thinner shell (around 100 nm) and a bigger cavity (around 200 nm), and possessed a certain level of magnetic response. The resulting magnetic emulsion particles were employed in the immobilization of lipase by two strategies to immobilized lipase onto the resulting magnetic composites directly (S-1) or using glutaraldehyde as a coupling agent (S-2), thus, experimental data showed that the thermal stability and reusability of immobilized lipase based on S-2 were higher than that of S-1.

Methacrylate based cross-linkers for improved thermomechanical properties and retention of radiation detection response in plastic scintillators

NASA Astrophysics Data System (ADS)

Mahl, Adam; Lim, Allison; Latta, Joseph; Yemam, Henok A.; Greife, Uwe; Sellinger, Alan

2018-03-01

Pulse shape discrimination (PSD) is an important method that can efficiently sort and separate neutron and gamma radiation signals. PSD is currently achieved in plastic scintillators by over-doping poly(vinyl toluene) (PVT) matrices with fluorescent molecules. Meaningful separation of the signals requires addition of >20 wt% 2,5-diphenyloxazole (PPO) fluor in PVT. At these concentrations PPO acts as a plasticizer, negatively affecting the physical properties of the final plastic such as hardness, machinability, and thermomechanical stability. This work addresses these issues by implementing a cost-effective solution using cross-linking chemistry via commercially available bisphenol A dimethacrylate (BPA-DM), and a synthesized fluorinated analogue. Both improve the physical properties of over-doped PPO based plastic scintillators without degrading the measured light yield or PSD and Figure of Merit (FoM). In addition, the fluorinated analogue appears to enhance the hydrophobicity of the surface of the plastic scintillators, which may improve the scintillators' resistance to water diffusion and subsequent radiation response degradation. The new formulations improve the feasibility of widely deploying long lifetime PSD capable plastic scintillators in large area coverage assemblies.

Development and characterization of adjustable refractive index scattering epoxy acrylate polymer layers

NASA Astrophysics Data System (ADS)

Eiselt, Thomas; Preinfalk, Jan; Gleißner, Uwe; Lemmer, Uli; Hanemann, Thomas

2017-03-01

Several polymer films for improved optical properties in optoelectronic devices are presented. In such optical applications, it is sometimes important to have a film with an adjusted refractive index, scattering properties, and a low surface roughness. These diffusing films can be used to increase the efficiency of optoelectronic components, such as organic light-emitting diodes. Three different epoxy acrylate mixtures containing Syntholux 291 EA, bisphenol A glycerolate dimethacrylate, and Sartomer SR 348 L are characterized and optimized with different additives. The adjustable refractive index of the material is achieved by chemical doping using 9-vinylcarbazole. Titanium nanoparticles in the mixtures generate light scattering and increase the refractive index additionally. A high-power stirrer is used to mix and disperse all chemical substances together to a homogenous mixture. The viscosity behavior of the mixtures is an important property for the selection of the production method and, therefore, the viscosity measurement results are presented. After the mixing, the monomer mixture is applied on glass substrates by screen printing. To initiate polymerization, the produced films are irradiated for 10 min with ultraviolet radiation and heat. Transmission measurements of the polymer matrix and roughness measurements complement the characterization.

Potential transducers based man-tailored biomimetic sensors for selective recognition of dextromethorphan as an antitussive drug.

PubMed

El-Naby, Eman H; Kamel, Ayman H

2015-09-01

A biomimetic potentiometric sensor for specific recognition of dextromethorphan (DXM), a drug classified according to the Drug Enforcement Administration (DEA) as a "drug of concern", is designed and characterized. A molecularly imprinted polymer (MIP), with special molecular recognition properties of DXM, was prepared by thermal polymerization in which DXM acted as template molecule, methacrylic acid (MAA) and acrylonitrile (AN) acted as functional monomers in the presence of ethylene glycol dimethacrylate (EGDMA) as crosslinker. The sensors showed a high selectivity and a sensitive response to the template in aqueous system. Electrochemical evaluation of these sensors revealed near-Nernstian response with slopes of 49.6±0.5 and 53.4±0.5 mV decade(-1) with a detection limit of 1.9×10(-6), and 1.0×10(-6) mol L(-1) DXM with MIP/MAA and MIP/AN membrane based sensors, respectively. Significantly improved accuracy, precision, response time, stability, selectivity and sensitivity were offered by these simple and cost-effective potentiometric sensors compared with other standard techniques. The method has the requisite accuracy, sensitivity and precision to assay DXM in pharmaceutical products. Copyright © 2015 Elsevier B.V. All rights reserved.

Construction of a simple optical sensor based on air stable lipid film with incorporated urease for the rapid detection of urea in milk.

PubMed

Nikoleli, Georgia-Paraskevi; Nikolelis, Dimitrios P; Methenitis, Constantinos

2010-08-18

This work describes the construction of a simple optical sensor for the rapid, selective and sensitive detection of urea in milk using air stable lipid films with incorporated urease. The lipid film is stabilized on a glass filter by polymerization using UV (ultra-violet) radiation prior its use. Methacrylic acid was the functional monomer, ethylene glycol dimethacrylate was the crosslinker and 2,2'-azobis-(2-methylpropionitrile) was the initiator. Urease is incorporated within this mixture prior to the polymerization. The presence of the enzyme in these films quenched this fluorescence and the colour became similar to that of the filters without the lipid films. A drop of aqueous solution of urea provided a "switching on" of the fluorescence which allows the rapid detection of this compound at the levels of 10(-8) M concentrations. The investigation of the effect of potent interferences included a wide range of compounds usually found in foods and also of proteins and lipids. These lipid membranes were used for the rapid detection of urea in milk. Copyright 2010 Elsevier B.V. All rights reserved.

Reduction of Non-Specific Protein Adsorption Using Poly(ethylene) Glycol (PEG) Modified Polyacrylate Hydrogels In Immunoassays for Staphylococcal Enterotoxin B Detection

PubMed Central

Charles, Paul T.; Stubbs, Veronte R.; Soto, Carissa M.; Martin, Brett D.; White, Brandy J.; Taitt, Chris R.

2009-01-01

Three PEG molecules (PEG-methacrylate, -diacrylate and -dimethacrylate) were incorporated into galactose-based polyacrylate hydrogels and their relative abilities to reduce non-specific protein adsorption in immunoassays were determined. Highly crosslinked hydrogels containing amine-terminated functionalities were formed and used to covalently attach antibodies specific for staphylococcal enterotoxin B (SEB). Patterned arrays of immobilized antibodies in the PEG-modified hydrogels were created with a PDMS template containing micro-channels for use in sandwich immunoassays to detect SEB. Different concentrations of the toxin were applied to the hydrogel arrays, followed with a Cy3-labeled tracer antibody specific for the two toxins. Fluorescence laser scanning confocal microscopy of the tracer molecules provided both qualitative and quantitative measurements on the detection sensitivity and the reduction in non-specific binding as a result of PEG incorporation. Results showed the PEG-modified hydrogel significantly reduced non-specific protein binding with a detection limit for SEB of 1 ng/mL. Fluorescence signals showed a 10-fold decrease in the non-specific binding and a 6-fold increase in specific binding of SEB. PMID:22389622

Molecularly imprinted solid-phase extraction for determination of tilmicosin in feed using high performance liquid chromatography.

PubMed

Zheng, Yaqiu; Liu, Yahong; Guo, Hongbin; He, Limin; Fang, Binghu; Zeng, Zhenling

2011-04-01

A simple, sensitive and reproducible molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatographic method was developed for monitoring tilmicosin in feeds. The polymers were prepared using tylosin as mimic template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking monomer, and chloroform as a solvent by bulk polymerization. Under the optimum MISPE conditions, the novel polymer sorbent can selectively extract and enrich tilmicosin from variety of feeds. The MISPE cartridge was better than non-imprinted, C(18) and HLB cartridges in terms of both recovery and precision. Mean recoveries of tilmicosin from five kinds of feeds spiked at 1, 10 and 50 mg kg(-1) ranged from 76.9% to 95.6%, with intra-day and inter-day relative standard deviation less than 7.6%. The linearity was ranged from 1.0 to 100 mg L(-1) for matrix standard solution (r=0.9990). The limit of detection was approximately 0.35 mg kg(-1) and the limit of quantification was approximately 0.98 mg kg(-1). There was cleaner chromatogram by using MISPE than C(18) and HLB SPE. Copyright © 2011 Elsevier B.V. All rights reserved.

Tensile bond strength of silicone-based soft denture liner to two chemically different denture base resins after various surface treatments.

PubMed

Akin, Hakan; Tugut, Faik; Guney, Umit; Kirmali, Omer; Akar, Turker

2013-01-01

This study evaluated the effect of various surface treatments on the tensile bond strength of a silicone-based soft denture liner to two chemically different denture base resins, heat-cured polymethyl methacrylate (PMMA), and light-activated urethane dimethacrylate or Eclipse denture base resin. PMMA test specimens were fabricated and relined with a silicone-based soft denture liner (group AC). Eclipse test specimens were prepared according to the manufacturer's recommendation. Before they were relined with a silicone-based soft denture liner, each received one of three surface treatments: untreated (control, group EC), Eclipse bonding agent applied (group EB), and laser-irradiated (group EL). Tensile bond strength tests (crosshead speed = 5 mm/min) were performed for all specimens, and the results were analyzed using the analysis of variance followed by Tukey's test (p = 0.05). Eclipse denture base and PMMA resins presented similar bond strengths to the silicone-based soft denture liner. The highest mean force was observed in group EL specimens, and the tensile bond strengths in group EL were significantly different (p < 0.05) from those in the other groups.

Design of Self-Healing Supramolecular Rubbers by Introducing Ionic Cross-Links into Natural Rubber via a Controlled Vulcanization.

PubMed

Xu, Chuanhui; Cao, Liming; Lin, Baofeng; Liang, Xingquan; Chen, Yukun

2016-07-13

Introducing ionic associations is one of the most effective approaches to realize a self-healing behavior for rubbers. However, most of commercial rubbers are nonpolar rubbers without now available functional groups to be converted into ionic groups. In this paper, our strategy was based on a controlled peroxide-induced vulcanization to generate massive ionic cross-links via polymerization of zinc dimethacrylate (ZDMA) in natural rubber (NR) and exploited it as a potential self-healable material. We controlled vulcanization process to retard the formation of covalent cross-link network, and successfully generated a reversible supramolecular network mainly constructed by ionic cross-links. Without the restriction of covalent cross-linkings, the NR chains in ionic supramolecular network had good flexibility and mobility. The nature that the ionic cross-links was easily reconstructed and rearranged facilitating the self-healing behavior, thereby enabling a fully cut sample to rejoin and retain to its original properties after a suitable self-healing process at ambient temperature. This study thus demonstrates a feasible approach to impart an ionic association induced self-healing function to commercial rubbers without ionic functional groups.

Controlled Transdermal Iontophoresis by Polypyrrole/Poly(Acrylic Acid) Hydrogel

NASA Astrophysics Data System (ADS)

Chansai, Phithupha; Sirivat, Anuvat

2008-03-01

Transdermal drug delivery system delivers a drug into a body at desired site and rate. The conductive polymer-hydrogel blend between polypyrrole (PPy) doped with anionic drug and poly(acrylic acid) (PAA) were developed as a matrix/carrier of drug for the transdermal drug delivery in which the characteristic releases depend on the electrical field applied. The PAA films and their blend films were prepared by solution casting using ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. A mechanical blending of PPy particles and PAA matrix was then carried out. Drug diffusions in the blended PPy/PAA hydrogel and the non-blended one were investigated and determined by using a modified Franz-diffusion cell with an acetate buffer, pH 5.5, at 37 0C, for a period of 48 hours to determine the effects of crosslinking ratio and electric field strength. Amounts of the released drug were measured by UV-Visible spectrophotometry. The diffusion coefficient of drug was determined through the Higuchi equation via different conditions, with and without an electric field. Moreover, thermal properties and electrical conductivity of the polypyrrole and drug-loaded polypyrrole were investigated by means of the thermogravimetric analysis and by using a two-point probe meter, respectively.

Determination of malachite green in aquatic products based on magnetic molecularly imprinted polymers.

PubMed

Lin, Zheng-zhong; Zhang, Hong-yuan; Peng, Ai-hong; Lin, Yi-dong; Li, Lu; Huang, Zhi-yong

2016-06-01

Magnetic molecularly imprinted polymers (MMIPs) were synthesized through precipitation polymerization using malachite green (MG) as template, methacrylic acid as monomer, ethylene dimethacrylate as crosslinker, and Fe3O4 magnetite as magnetic component. MMIPs were characterized by scanning electron microscopy, Fourier transform infrared spectrometry, and vibrating sample magnetometry. Under the optimum condition, the MMIPs obtained exhibited quick binding kinetics and high affinity to MG in the solution. Scatchard plot analysis revealed that the MMIPs contained only one type of binding site with dissociation constant of 24.0 μg mL(-1). The selectivity experiment confirmed that the MMIPs exhibited higher selective binding capacity for MG than its structurally related compound (e.g., crystal violet). As a sorbent for the extraction of MG in sample preparation, MMIPs together with the absorbed analytes could easily be separated from the sample matrix with an external magnet. After elution with methanol/acetic acid (9:1, v/v), MG in the eluent was determined by high-performance liquid chromatography coupled with UV detector with recoveries of 94.0-115%. Results indicated that the as-prepared MMIPs are promising materials for MG analysis in aquatic products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and application of a nanoporous ion-imprinted polymer for the separation and preconcentration of trace amounts of vanadium from food samples before determination by electrothermal atomic absorption spectrometry.

PubMed

Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Dehghanpoor Frashah, Shahab

2016-04-01

A vanadium ion-imprinted polymer was synthesized in the presence of V(V) and N-benzoyl-N-phenyl hydroxyl amine using 4-vinyl pyridine as the monomer, ethylene glycol dimethacrylate as the cross linker and 2,2'-azobis(isobutyronitrile) as the initiator. The imprinted V(V) ions were completely removed by leaching the polymer with 5 mol/L nitric acid, and the polymer structure was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The ion-imprinted polymer was used as the sorbent in the development of the solid-phase extraction method for V(V) prior to its determination by electrothermal atomic absorption spectrometry. The maximum sorption capacity for V(V) ions was 26.7 mg/g at pH 4.0. Under the optimum conditions, for a sample volume of 150.0 mL, an enrichment factor of 289.0 and a detection limit of 6.4 ng/L were obtained. The developed method was successfully applied to the determination of vanadium in parsley, zucchini, black tea, rice, and water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of 1-naphthyl methyl carbamate in water by utilizing a surface molecularly imprinted polymer

NASA Astrophysics Data System (ADS)

So, Juhyok; Pang, Cholho; Dong, Hongxing; Jang, Paeksan; U, Juhyok; Ri, Kumchol; Yun, Cholyong

2018-05-01

Surface molecularly imprinting polymer (SMIP) was utilized in the removal of a residual pesticide (carbaryl (CBL)) in water and simulated fruit juice. Being the crosslinking agent, ethylene glycol dimethacrylate (EGDMA) was copolymerized with the monomer, methacrylic acid (MAA) and CBL as the template molecules on the surface of the silica gel particles to produce the SMIP adsorbents. The SMIP adsorbents showed good selectivity and good adsorption capacity for CBL in the competitive adsorptions with two structurally related carbamate pesticides. The effect of the pretreatment solvents on the adsorption capacity of the SMIP adsorbent was investigated with the results of the numerical simulations. The adsorption isotherms and the adsorption kinetics were well described by the Freundlich equilibrium model and the pseudo-second-order kinetic model, respectively. Scatchard plot analysis revealed that there were two classes of binding sites populated in the SMIP adsorbents. In addition, the good selective adsorption of CBL by the SMIP adsorbent in a simulated fruit juice containing vitamin C and fructose indicated the great potential of the SMIP adsorbents to remove residual pesticide in food industry and processing industry for agricultural products.

Does the light source affect the repairability of composite resins?

PubMed

Karaman, Emel; Gönülol, Nihan

2014-01-01

The aim of this study was to examine the effect of the light source on the microshear bond strength of different composite resins repaired with the same substrate. Thirty cylindrical specimens of each composite resin--Filtek Silorane, Filtek Z550 (3M ESPE), Gradia Direct Anterior (GC), and Aelite Posterior (BISCO)--were prepared and light-cured with a QTH light curing unit (LCU). The specimens were aged by thermal cycling and divided into three subgroups according to the light source used--QTH, LED, or PAC (n = 10). They were repaired with the same substrate and a Clearfil Repair Kit (Kuraray). The specimens were light-cured and aged for 1 week in distilled water at 37 °C. The microshear bond strength and failure modes were assessed. There was no significant difference in the microshear bond strength values among the composite resins, except for the Filtek Silorane group that showed significantly lower bond strength values when polymerized with the PAC unit compared to the QTH or LED unit. In conclusion, previously placed dimethacrylate-based composites can be repaired with different light sources; however, if the composite to be repaired is silorane-based, then using a QTH or LED device may be the best option.

Miniature probe for the delivery and monitoring of a photopolymerizable material

NASA Astrophysics Data System (ADS)

Schmocker, Andreas; Khoushabi, Azadeh; Schizas, Constantin; Bourban, Pierre-Etienne; Pioletti, Dominique P.; Moser, Christophe

2015-12-01

Photopolymerization is a common method to cure materials initially in a liquid state, such as dental implants or bone or tissue fillers. Recent advances in the development of biocompatible gel- and cement-systems open up an avenue for in situ photopolymerization. For minimally invasive surgery, such procedures require miniaturized surgical endoscopic probes to activate and control photopolymerization in situ. We present a miniaturized light probe in which a photoactive material can be (1) mixed, pressurized, and injected, (2) photopolymerized/photoactivated, and (3) monitored during the chemical reaction. The device is used to implant and cure poly(ethylene glycol) dimethacrylate-hydrogel-precursor in situ with ultraviolet A (UVA) light (365 nm) while the polymerization reaction is monitored in real time by collecting the fluorescence and Raman signals generated by the 532-nm excitation light source. Hydrogels could be delivered, photopolymerized, and monitored by the probe up to a curing depth of 4 cm. The size of the photopolymerized samples could be correlated to the fluorescent signal collected by the probe, and the reproducibility of the procedure could be demonstrated. The position of the probe tip inside a bovine caudal intervertebral disc could be estimated in vitro based on the collected fluorescence and Raman signal.

Vapor-liquid interfacial reaction to fabricate superhydrophilic and underwater superoleophobic thiol-ene/silica hybrid decorated fabric for oil/water separation

NASA Astrophysics Data System (ADS)

Li, Hongqiang; Liang, Tao; Lai, Xuejun; Su, Xiaojing; Zhang, Lin; Zeng, Xingrong

2018-01-01

With oil spill accidents and oil industrial wastewater increasing, oil/water separation has attracted much attention in recent years. Herein, we report the fabrication of superhydrophilic and underwater superoleophobic thiol-ene/silica hybrid decorated fabrics for oil/water separation via vapor-liquid interfacial reaction. It is based on sol-gel reaction of tetraethyl orthosilicate (TEOS) to generate silica and thiol-ene reaction between poly(ethylene glycol) dimethacrylate (PEGDMA) and trimethylolpropane tris(3-mercaptopropionate) (TTMP) to form crosslinked hydrophilic polymer on polyester fabric under the catalysis of butylamine/ammonia vapor. The chemical structure of the surfaces on thiol-ene/silica hybrid decorated fabric was confirmed by FTIR and XPS, and obvious micro-nano morphology and roughness were observed with SEM and AFM. The water contact angle of the fabric attained 0° in 0.36 s, and the underwater oil contact angle reached up to 160°. Importantly, the fabric exhibited high separation efficiency at 99.5%, fast water flux above 71600 Lm-2h-1 and excellent recyclability in oil/water separation. Our findings open a new strategy to fabricate organic-inorganic hybrid superhydrophobic and underwater superoleophobic materials for oil/water separation.

Application of magnetic molecularly imprinted polymers for extraction of imidacloprid from eggplant and honey.

PubMed

Kumar, Niranjan; Narayanan, Neethu; Gupta, Suman

2018-07-30

A magnetic molecularly imprinted polymer (MMIP) adsorbent for imidacloprid was prepared using non-covalent approach with functionalized nano Fe 3 O 4 particles (magnetic cores), imidacloprid (template), acrylic acid (functional monomer), ethylene glycol dimethacrylate (cross linker) and azobisisobutyronitrile (initiator) and used for selective separation of imidacloprid from honey and vegetable samples. The polymers were characterized using FT-IR spectroscopy, SEM and TEM images. For analysis of imidacloprid LC-MS/MS equipment was used. Adsorption kinetics was best explained by pseudo-second-order kinetic model. Adsorption data fitted well into linearized Freundlich equation (R 2  > 0.98). Scatchard plot analysis indicates the presence of two classes of binding sites in the MMIPs with the C max of 1889.6 µg g -1 and 65448.9 µg g -1 , respectively. MMIPs demonstrated much higher affinity for imidacloprid over structurally similar analogues acetamiprid (α = 23.59) and thiamethoxam (α = 17.15). About 87.1 ± 5.0% and 90.6 ± 5.6% of the added imidacloprid was recovered from MMIPs in case of fortified eggplant and honey samples, respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

The in situ synthesis of PbS nanocrystals from lead(II) n-octylxanthate within a 1,3-diisopropenylbenzene–bisphenol A dimethacrylate sulfur copolymer

PubMed Central

Bear, J. C.; Mayes, A. G.; Parkin, I. P.; O'Brien, P.

2017-01-01

The synthesis of lead sulfide nanocrystals within a solution processable sulfur ‘inverse vulcanization’ polymer thin film matrix was achieved from the in situ thermal decomposition of lead(II) n-octylxanthate, [Pb(S2COOct)2]. The growth of nanocrystals within polymer thin films from single-source precursors offers a faster route to networks of nanocrystals within polymers when compared with ex situ routes. The ‘inverse vulcanization’ sulfur polymer described herein contains a hybrid linker system which demonstrates high solubility in organic solvents, allowing solution processing of the sulfur-based polymer, ideal for the formation of thin films. The process of nanocrystal synthesis within sulfur films was optimized by observing nanocrystal formation by X-ray photoelectron spectroscopy and X-ray diffraction. Examination of the film morphology by scanning electron microscopy showed that beyond a certain precursor concentration the nanocrystals formed were not only within the film but also on the surface suggesting a loading limit within the polymer. We envisage this material could be used as the basis of a new generation of materials where solution processed sulfur polymers act as an alternative to traditional polymers. PMID:28878986

Flexural properties of ethyl or methyl methacrylate-UDMA blend polymers.

PubMed

Kanie, Takahito; Kadokawa, Akihiko; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

2010-10-01

Light-curing polyethyl methacrylate (PEMA)-urethane dimethacrylate (UDMA) resins and polymethyl methacrylate (PMMA)-UDMA resins were prepared by two processes. For first step, PEMA or PMMA powders were fully dissolved in ethyl methacrylate (EMA) or methyl methacrylate (MMA) and then the PEMA-EMA/PMMA-MMA mixtures were mixed with UDMA. The flexural properties of cured PEMA-UDMA and PMMA-UDMA polymers were measured using two PEMA (Mw: 300,000-400,000 and 650,000-1,000,000) and three PMMA (Mw: 30,000-60,000, 350,000 and 650,000-1,000,000) powders with different molecular weight, four mixing ratios of PMMA-MMA, and three mixing ratios of PMMA-MMA mixture and UDMA oligomer. Polymers with PMMA(Mw: 350,000) MMA=25/50, and with PMMA(Mw: 350,000)-MMA/UDMA=1/2 and =1/1, showed no-fracture in a flexural test at 1 mm/min and flexural strength and flexural modulus showed no significant difference compared with those of commercially available heat- and self-curing acrylic resins (p>0.01). Within limitation of this investigation, methyl methacrylate-UDMA blend polymer of this composition is available for denture base resin.

Comparison of Positively and Negatively Charged Achiral Co-Monomers Added to Cyclodextrin Monolith: Improved Chiral Separations in Capillary Electrochromatography

PubMed Central

Lu, Yang; Shamsi, Shahab A.

2014-01-01

Cyclodextrins (CDs) and their derivatives have been one of the most popular and successful chiral additives used in electrokinetic chromatography because of the presence of multiple chiral centers, which leads to multiple chiral interactions. However, there has been relatively less published work on the use of CDs as monolithic media for capillary electrochromatography (CEC). The goal of this study was to show how the addition of achiral co-monomer to a polymerizable CD such as glycidyl methacrylate β-cyclodextrin (GMA/β-CD) can affect the enantioselective separations in monolithic CEC. To achieve this goal, polymeric monoliths columns were prepared by co-polymerizing GMA/β-CD with cationic or anionic achiral co-monomers [(2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and vinyl benzyltrimethyl-ammonium (VBTA)] in the presence of conventional crosslinker (ethylene dimethacrylate) and ternary porogen system including butanediol, propanol and water. A total of 34 negatively charged compounds, 30 positively charged compounds and 33 neutral compounds were screened to compare the enantioresolution capability on the GMA/β-CD, GMA/β-CD-VBTA and GMA/β-CD-AMPS monolithic columns. PMID:24108813

Smart coumarin-tagged imprinted polymers for the rapid detection of tamoxifen.

PubMed

Ray, Judith V; Mirata, Fosca; Pérollier, Celine; Arotcarena, Michel; Bayoudh, Sami; Resmini, Marina

2016-03-01

A signalling molecularly imprinted polymer was synthesised for easy detection of tamoxifen and its metabolites. 6-Vinylcoumarin-4-carboxylic acid (VCC) was synthesised from 4-bromophenol to give a fluorescent monomer, designed to switch off upon binding of tamoxifen. Clomiphene, a chlorinated analogue, was used as the template for the imprinting, and its ability to quench the coumarin fluorescence when used in a 1:1 ratio was demonstrated. Tamoxifen and 4-hydroxytamoxifen were also shown to quench coumarin fluorescence. Imprinted and non-imprinted polymers were synthesised using VCC, methacrylic acid as a backbone monomer and ethylene glycol dimethacrylate as cross-linker, and were ground and sieved to particle sizes ranging between 45 and 25 μm. Rebinding experiments demonstrate that the imprinted polymer shows very strong affinity for both clomiphene and tamoxifen, while the non-imprinted polymer shows negligible rebinding. The fluorescence of the imprinted polymer is quenched by clomiphene, tamoxifen and 4-hydroxytamoxifen. The switch off in fluorescence of the imprinted polymer under these conditions could also be detected under a UV lamp with the naked eye, making this matrix suitable for applications when coupled with a sample preparation system.

Cholesterol-imprinted macroporous monoliths: Preparation and characterization.

PubMed

Stepanova, Mariia А; Kinziabulatova, Lilia R; Nikitina, Anna A; Korzhikova-Vlakh, Evgenia G; Tennikova, Tatiana B

2017-11-01

The development of sorbents for selective binding of cholesterol, which is a risk factor for cardiovascular disease, has a great importance for analytical science and medicine. In this work, two series of macroporous cholesterol-imprinted monolithic sorbents differing in the composition of functional monomers (methacrylic acid, butyl methacrylate, 2-hydroxyethyl methacrylate and ethylene dimethacrylate), amount of a template (4, 6 and 8 mol%) used for molecular imprinting, as well as mean pore size were synthesized by in situ free-radical process in stainless steel housing of 50 mm × 4.6 mm i.d. All prepared materials were characterized regarding to their hydrodynamic permeability and porous properties, as well as examined by BET and SEM methods. Imprinting factors, apparent dynamic dissociation constants, the maximum binding capacity, the number of theoretical plates and the height equivalent to a theoretical palate of MIP monoliths at different mobile phase flow rates were determined. The separation of a mixture of structural analogues, namely, cholesterol and prednisolone, was demonstrated. Additionally, the possibility of using the developed monoliths for cholesterol solid-phase extraction from simulated biological solution was shown. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lanthanide-IMAC enrichment of carbohydrates and polyols.

PubMed

Schemeth, Dieter; Rainer, Matthias; Messner, Christoph B; Rode, Bernd M; Bonn, Günther K

2014-03-01

In this study a new type of immobilized metal ion affinity chromatography resin for the enrichment of carbohydrates and polyols was synthesized by radical polymerization reaction of vinyl phosphonic acid and 1,4-butandiole dimethacrylate using azo-bis-isobutyronitrile as radical initiator. Interaction between the chelated trivalent lanthanide ions and negatively charged hydroxyl groups of carbohydrates and polyols was observed by applying high pH values. The new method was evaluated by single standard solutions, mixtures of standards, honey and a more complex extract of Cynara scolymus. The washing step was accomplished by acetonitrile in excess volumes. Elution of enriched carbohydrates was successfully performed with deionized water. The subsequent analysis was carried out with matrix-free laser desorption/ionization-time of flight mass spectrometry involving a TiO2 -coated steel target, especially suitable for the measurement of low-molecular-weight substances. Quantitative analysis of the sugar alcohol xylitol as well as the determination of the maximal loading capacity was performed by gas chromatography in conjunction with mass spectrometric detection after chemical derivatization. In a parallel approach quantum mechanical geometry optimizations were performed in order to compare the coordination behavior of various trivalent lanthanide ions. Copyright © 2013 John Wiley & Sons, Ltd.

In-situ functionalized monolithic polysiloxane-polymethacrylate composite materials from polythiol-ene double click reaction in capillary column format for enantioselective nano-high-performance liquid chromatography.

PubMed

Wolter, Marc; Lämmerhofer, Michael

2017-05-12

This work reports on the proof-of-principle of preparation of novel one step in-situ functionalized monolithic polysiloxane-polymethacrylate composite materials in capillary columns for enantioselective nano-HPLC using a thiol-ene click reaction. Quinine carbamate as functional monomer and ethylene dimethacrylate as crosslinker were both used as ene components in a thermally initiated double click-type polymerization reaction with poly(3-mercaptopropyl)methylsiloxane as thiol component in presence of 1-propanol as porogenic solvent. Elemental analysis and on-capillary fluorescence measurement proved the successful incorporation of the functional chiral monomer into the polymer. Scanning electron microscopy images revealed a macroporous polymer morphology which is typical for a nucleation and growth mechanism of pore formation. The individual microglobules appear relatively spherical and smooth indicating a non-porous nature. Nano-HPLC experiments of the chiral monolithic capillary column provided successful enantiomer separation of N-3,5-dinitrobenzoylleucine as test compound in polar organic elution mode clearly documenting the successful implementation of the proposed concept towards new functionalized monolithic composite materials. Copyright © 2017 Elsevier B.V. All rights reserved.

A facile and efficient single-step approach for the fabrication of vancomycin functionalized polymer-based monolith as chiral stationary phase for nano-liquid chromatography.

PubMed

Xu, Dongsheng; Shao, Huikai; Luo, Rongying; Wang, Qiqin; Sánchez-López, Elena; Fanali, Salvatore; Marina, Maria Luisa; Jiang, Zhengjin

2018-07-06

A facile single-step preparation strategy for fabricating vancomycin functionalized organic polymer-based monolith within 100μm fused-silica capillary was developed. The synthetic chiral functional monomer, i.e 2-isocyanatoethyl methacrylate (ICNEML) derivative of vancomycin, was co-polymerized with the cross-linker ethylene dimethacrylate (EDMA) in the presence of methanol and dimethyl sulfoxide as the selected porogens. The co-polymerization conditions were systematically optimized in order to obtain satisfactory column performance. Adequate permeability, stability and column morphology were observed for the optimized poly(ICNEML-vancomycin-co-EDMA) monolith. A series of chiral drugs were evaluated on the monolith in either polar organic-phase or reversed-phase modes. After the optimization of separation conditions, baseline or partial enantioseparation were obtained for series of drugs including thalidomide, colchicine, carteolol, salbutamol, clenbuterol and several other β-blockers. The proposed single-step approach not only resulted in a vancomycin functionalized organic polymer-based monolith with acceptable performance, but also significantly simplified the preparation procedure by reducing time and labor. Copyright © 2018 Elsevier B.V. All rights reserved.

Phosphate barrier on pore-filled cation-exchange membrane for blocking complexing ions in presence of non-complexing ions

NASA Astrophysics Data System (ADS)

Chavan, Vivek; Agarwal, Chhavi; Shinde, Rakesh N.

2018-06-01

In present work, an approach has been used to form a phosphate groups bearing surface barrier on a cation-exchange membrane (CEM). Using optimized conditions, the phosphate bearing monomer bis[2-(methacryloyloxy)ethyl] phosphate has been grafted on the surface of the host poly(ethersulfone) membranes using UV light induced polymerization. The detailed characterizations have shown that less than a micron layer of phosphate barrier is formed without disturbing the original microporous structure of the host membrane. The pores of thus formed membrane have been blocked by cationic-gel formed by in situ UV-initiator induced polymerization of 2-acrylamido-2-methyl-1-propane sulphonic acid along with crosslinker ethylene glycol dimethacrylate in the pores of the membrane. UV-initiator is required for pore-filling as UV light would not penetrate the interior matrix of the membrane. The phosphate functionalized barrier membrane has been examined for permselectivity using a mixture of representative complexing Am3+ ions and non-complexing Cs+ ions. This experiment has demonstrated that complex forming Am3+ ions are blocked by phosphate barrier layer while non-complexing Cs+ ions are allowed to pass through the channels formed by the crosslinked cationic gel.

Effect of bioactive glass-containing resin composite on dentin remineralization.

PubMed

Lee, Myoung Geun; Jang, Ji-Hyun; Ferracane, Jack L; Davis, Harry; Bae, Han Eul; Choi, Dongseok; Kim, Duck-Su

2018-05-25

The purpose of this study was to evaluate the effect of bioactive glass (BAG)-containing composite on dentin remineralization. Sixty-six dentin disks with 3 mm thickness were prepared from thirty-three bovine incisors. The following six experimental groups were prepared according to type of composite (control and experimental) and storage solutions (simulated body fluid [SBF] and phosphate-buffered saline [PBS]): 1 (undemineralized); 2 (demineralized); 3 (demineralized with control in SBF); 4 (demineralized with control in PBS); 5 (demineralized with experimental composite in SBF); and 6 (demineralized with experimental composite in PBS). BAG65S (65% Si, 31% Ca, and 4% P) was prepared via the sol-gel method. The control composite was made with a 50:50 Bis-GMA:TEGDMA resin matrix, 57 wt% strontium glass, and 15 wt% aerosol silica. The experimental composite had the same resin and filler, but with 15 wt% BAG65S replacing the aerosol silica. For groups 3-6, composite disks (20 × 10 × 2 mm) were prepared and approximated to the dentin disks and stored in PBS or SBF for 2 weeks. Micro-hardness measurements, attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and field-emission scanning electron microscopy (FE-SEM) was investigated. The experimental BAG-containing composite significantly increased the micro-hardness of the adjacent demineralized dentin. ATR-FTIR revealed calcium phosphate peaks on the surface of the groups which used experimental composite. FE-SEM revealed surface deposits partially occluding the dentin surface. No significant difference was found between SBF and PBS storage. BAG-containing composites placed in close proximity can partially remineralize adjacent demineralized dentin. Copyright © 2018. Published by Elsevier Ltd.

The effect of high fiber fraction on some mechanical properties of unidirectional glass fiber-reinforced composite.

PubMed

Abdulmajeed, Aous A; Närhi, Timo O; Vallittu, Pekka K; Lassila, Lippo V

2011-04-01

This study was designed to evaluate the effect of an increase of fiber-density on some mechanical properties of higher volume fiber-reinforced composite (FRC). Five groups of FRC with increased fiber-density were fabricated and two additional groups were prepared by adding silanated barium-silicate glass fillers (0.7 μm) to the FRC. The unidirectional E-glass fiber rovings were impregnated with light-polymerizable bisGMA-TEGDMA (50-50%) resin. The fibers were pulled through a cylindrical mold with an opening diameter of 4.2mm, light cured for 40s and post-cured at elevated temperature. The cylindrical specimens (n=12) were conditioned at room temperature for 2 days before testing with the three-point bending test (Lloyd Instruments Ltd.) adapted to ISO 10477. Fiber-density was analyzed by combustion and gravimetric analyzes. ANOVA analysis revealed that by increasing the vol.% fraction of E-glass fibers from 51.7% to 61.7% there was a change of 27% (p<0.05) in the modulus of elasticity, 34% (p<0.05) in the toughness, and 15% (p<0.05) in the load bearing capacity, while there was only 8% (p<0.05) increase in the flexural strength although it was statistically insignificant. The addition of particulate fillers did not improve the mechanical properties. This study showed that the properties of FRC could be improved by increasing fibervolume fraction. Modulus of elasticity, toughness, and load bearing capacity seem to follow the law of ratio of quantity of fibers and volume of the polymer matrix more precisely than flexural strength when high fiber-density is used. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Model resin composites incorporating ZnO-NP: activity against S. mutans and physicochemical properties characterization

PubMed Central

Brandão, Natasha Lamego; Portela, Maristela Barbosa; Maia, Luciane Cople; Antônio, Andréa; Silva, Vanessa Loureiro Moreira e

2018-01-01

Abstract Although resin composites are widely used in the clinical practice, the development of recurrent caries at composite-tooth interface still remains as one of the principal shortcomings to be overcome in this field. Objectives To evaluate the activity against S. mutans biofilm of model resin composites incorporating different concentrations of ZnO-nanoparticles (ZnO-NP) and characterize their physicochemical properties. Materials and Methods Different concentrations of ZnO-NP (wt.%): E1=0, E2=0.5, E3=1, E4=2, E5=5 and E6=10 were incorporated into a model resin composite consisting of Bis-GMA-TEGDMA and barium borosilicate particles. The activity against S. mutans biofilm was evaluated by metabolic activity and lactic acid production. The following physicochemical properties were characterized: degree of conversion (DC%), flexural strength (FS), elastic modulus (EM), hardness (KHN), water sorption (Wsp), water solubility (Wsl) and translucency (TP). Results E3, E4, E5 and E6 decreased the biofilm metabolic activity and E5 and E6 decreased the lactic acid production (p<0.05). E6 presented the lowest DC% (p<0.05). No significant difference in FS and EM was found for all resin composites (p>0.05). E5 and E6 presented the lowest values of KHN (p<0.05). E6 presented a higher Wsp than E1 (p<0.05) and the highest Wsl (p<0.05). The translucency significantly decreased as the ZnO- NP concentration increased (p<0.05). Conclusions The incorporation of 2 – 5 wt.% of ZnO-NP could endow antibacterial activity to resin composites, without jeopardizing their physicochemical properties. PMID:29742262

Kinetics and mechanics of photo-polymerized triazole-containing thermosetting composites via the copper(I)-catalyzed azide-alkyne cycloaddition

PubMed Central

Song, Han Byul; Wang, Xiance; Patton, James R.; Stansbury, Jeffrey W.; Bowman, Christopher N.

2017-01-01

Objectives Several features necessary for polymer composite materials in practical applications such as dental restorative materials were investigated in photo-curable CuAAC (copper(I)-catalyzed azide-alkyne cycloaddition) thermosetting resin-based composites with varying filler loadings and compared to a conventional BisGMA/TEGDMA based composite. Methods Tri-functional alkyne and di-functional azide monomers were synthesized for CuAAC resins and incorporated with alkyne-functionalized silica microfillers for CuAAC composites. Polymerization kinetics, in situ temperature change, and shrinkage stress were monitored simultaneously with a tensometer coupled with FTIR spectroscopy and a data-logging thermocouple. The glass transition temperature was analyzed by dynamic mechanical analysis. Flexural modulus/strength and flexural toughness were characterized in three-point bending on a universal testing machine. Results The photo-CuAAC polymerization of composites containing between 0 and 60 wt% microfiller achieved ~99% conversion with a dramatic reduction in the maximum heat of reaction (~20 °C decrease) for the 60 wt% filled CuAAC composites as compared with the unfilled CuAAC resin. CuAAC composites with 60 wt% microfiller generated more than twice lower shrinkage stress of 0.43±0.01 MPa, equivalent flexural modulus of 6.1±0.7 GPa, equivalent flexural strength of 107±9 MPa, and more than 10 times higher energy absorption of 10±1 MJ m−3 when strained to 11% relative to BisGMA-based composites at equivalent filler loadings. Significance Mechanically robust and highly tough, photo-polymerized CuAAC composites with reduced shrinkage stress and a modest reaction exotherm were generated and resulted in essentially complete conversion. PMID:28363645

Influence of glass particle size of resin cements on bonding to glass ceramic: SEM and bond strength evaluation.

PubMed

Valentini, Fernanda; Moraes, Rafael R; Pereira-Cenci, Tatiana; Boscato, Noéli

2014-05-01

This study investigated the effect of the filler particle size (micron or submicron) of experimental resin cements on the microtensile bond strength to a glass-ceramic pretreated with hydrofluoric acid (HFA) etching or alumina airborne-particle abrasion (AA). Cements were obtained from a Bis-GMA/TEGDMA mixture filled with 60 mass% micron-sized (1 ± 0.2 µm) or submicron-sized (180 ± 30 µm) Ba-Si-Al glass particles. Ceramic blocks (PM9; VITA) were treated with 10% HFA for 60 s or AA for 15 s. Silane and adhesive were applied. Ceramic blocks were bonded to resin composite blocks (Z250; 3M ESPE) using one of the cements. Bonded specimens were sectioned into beams (n = 20/group) and subjected to microtensile bond strength tests. Data were analyzed using ANOVA and Student-Newman-Keuls' tests (5%). Failure modes were classified under magnification. Morphologies of the treated ceramic surfaces and bonded interfaces were evaluated by scanning electron microscopy. The HFA-submicron group had lower bond strengths than the other groups. All AA-submicron specimens debonded prematurely. Mixed failures were predominant for HFA groups, whereas interfacial failures predominated for AA groups. SEM revealed a honeycomb-like aspect in the HFA-treated ceramic, whereas the AA-treated groups showed an irregular retentive pattern. Continuity of cement infiltration along the bonded interface was more uniform for HFA-treated compared to AA-treated specimens. Cracks toward the bulk of the ceramic were observed in AA-treated specimens. Particle size significantly influenced the ceramic bond strength, whereas surface treatment had a minor effect. Copyright © 2014 Wiley Periodicals, Inc.

Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.

Our objective was to investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials. Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to localmore » structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significantly, for the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.« less

Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

DOE PAGES

Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; ...

2014-07-28

Our objective was to investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials. Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to localmore » structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significantly, for the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified.« less

Mechanical properties and ion release from bioactive restorative composites containing glass fillers and calcium phosphate nano-structured particles.

PubMed

Chiari, Marina D S; Rodrigues, Marcela C; Xavier, Tathy A; de Souza, Eugen M N; Arana-Chavez, Victor E; Braga, Roberto R

2015-06-01

To evaluate the effect of the replacement of barium glass by dicalcium phosphate dihydrate (DCPD) particles on the mechanical properties and degree of conversion (DC) of composites. Additionally, calcium and hydrogen phosphate (HPO4(2-)) release were followed for 28 days. Nine composites containing equal parts (in mols) of BisGMA and TEGDMA and 40, 50 or 60 vol% of total filler were manipulated. Filler phase was constituted by silanated barium glass and 0%, 10% or 20% of DCPD particles. DC was determined by near-FTIR. Biaxial flexural strength (BFS) and modulus (E) were tested using the "piston on three balls" method, while fracture toughness (KIc) used the "single edge notched beam" method. Specimens were tested after 24h and 28 days in water. Ion release was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey (DC and ion release) or Kruskal-Wallis/Mann-Whitney (mechanical properties; alpha: 5%). DC was not affected by DCPD. The presence of DCPD reduced BFS for both storage times, while differences in E became evident after 28 days. After 24h, KIc increased with the addition of DCPD; after 28 days, however, KIc decreased only for DCPD-containing composites. Calcium release was similar for both DCPD contents and remained fairly constant during the 28-day period. Overall, HPO4(2-) release was higher at 7 days and did not decrease after 14 days. The composite with the highest filler level and 10% DCPD represented the best compromise between mechanical properties after aging in water and ion release. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Model resin composites incorporating ZnO-NP: activity against S. mutans and physicochemical properties characterization.

PubMed

Brandão, Natasha Lamego; Portela, Maristela Barbosa; Maia, Luciane Cople; Antônio, Andréa; Silva, Vanessa Loureiro Moreira E; Silva, Eduardo Moreira da

2018-01-01

Although resin composites are widely used in the clinical practice, the development of recurrent caries at composite-tooth interface still remains as one of the principal shortcomings to be overcome in this field. Objectives To evaluate the activity against S. mutans biofilm of model resin composites incorporating different concentrations of ZnO-nanoparticles (ZnO-NP) and characterize their physicochemical properties. Materials and Methods Different concentrations of ZnO-NP (wt.%): E1=0, E2=0.5, E3=1, E4=2, E5=5 and E6=10 were incorporated into a model resin composite consisting of Bis-GMA-TEGDMA and barium borosilicate particles. The activity against S. mutans biofilm was evaluated by metabolic activity and lactic acid production. The following physicochemical properties were characterized: degree of conversion (DC%), flexural strength (FS), elastic modulus (EM), hardness (KHN), water sorption (Wsp), water solubility (Wsl) and translucency (TP). Results E3, E4, E5 and E6 decreased the biofilm metabolic activity and E5 and E6 decreased the lactic acid production (p<0.05). E6 presented the lowest DC% (p<0.05). No significant difference in FS and EM was found for all resin composites (p>0.05). E5 and E6 presented the lowest values of KHN (p<0.05). E6 presented a higher Wsp than E1 (p<0.05) and the highest Wsl (p<0.05). The translucency significantly decreased as the ZnO- NP concentration increased (p<0.05). Conclusions The incorporation of 2 - 5 wt.% of ZnO-NP could endow antibacterial activity to resin composites, without jeopardizing their physicochemical properties.

The addition of nanostructured hydroxyapatite to an experimental adhesive resin.

PubMed

Leitune, Vicente Castelo Branco; Collares, Fabrício Mezzomo; Trommer, Rafael Mello; Andrioli, Daniela Guerra; Bergmann, Carlos Pérez; Samuel, Susana Maria Werner

2013-04-01

Was produced nanostructured hydroxyapatite (HAnano) and evaluated the influence of its incorporation in an adhesive resin. HAnano was produced by a flame-based process and was characterized by scanning electron microscopy. The surface area, particle size, micro-Raman and cytotoxicity were evaluated. The organic phase was formulated by mixing 50 wt.% Bis-GMA, 25 wt.% TEGDMA, and 25 wt.% HEMA. HAnano was added at seven different concentrations: 0; 0.5; 1; 2; 5; 10 and 20 wt.%. Adhesive resins with hydroxyapatite incorporation were evaluated for their radiopacity, degree of conversion, flexural strength, softening in solvent and microshear bond strength. The data were analyzed by one-way ANOVA and Tukey's post hoc test (α=0.05), except for softening in solvent (paired t-test) and cytotoxicity (two-way ANOVA and Bonferroni). HAnano presented 15.096 m(2)/g of specific surface area and a mean size of 26.7 nm. The radiopacity values were not different from those of 1-mm aluminium. The degree of conversion ranged from 52.2 to 63.8%. The incorporation of HAnano did not influence the flexural strength, which ranged from 123.3 to 143.4MPa. The percentage of reduction of the microhardness after immersion in the solvent became lower as the HAnano concentration increased. The addition of 2% nanostructured hydroxyapatite resulted in a higher value of microshear bond strength than the control group (p<0.05). The incorporation of 2% of nanostructured hydroxyapatite into an adhesive resin presented the best results. The incorporation of nanostructured hydroxyapatite increases the adhesive properties and may be a promising filler for adhesive resin. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of admixed high-density polyethylene (HDPE) spheres on contraction stress and properties of experimental composites.

PubMed

Ferracane, J L; Ferracane, L L; Braga, R R

2003-07-15

Additives that provide stress relief may be incorporated into dental composites to reduce contraction stress (CS). This study attempted to test the hypothesis that conventional fillers could be replaced by high-density polyethylene (HDPE) spheres in hybrid and nanofill composites to reduce CS, but with minimal effect on mechanical properties. Nanofill and hybrid composites were made from a Bis-GMA/TEGDMA resin having either all silica nanofiller or 75 wt.% strontium glass + 5 wt.% silica and replacing some of the nanofiller or the glass with 0%, 5% (hybrid only), 10% or 20 wt.% HDPE. The surface of the HDPE was either left untreated or had a reactive gas surface treatment (RGST). Contraction stress (CS) was monitored for 10 min in a tensilometer (n = 5) after light curing for 60 s at 390 mW/cm(2). Other specimens (n = 5) were light cured 40 s from two sides in a light-curing unit and aged 1 d in water before testing fracture toughness (K(Ic)), flexure strength (FS), and modulus (E). Results were analyzed by ANOVA with Tukey's multiple comparison test at p < 0.05. There was no difference between composites with RGST and untreated HDPE except for FS-10% HDPE hybrid (RGST higher). An increased level of HDPE reduced contraction stress for both types of composites. Flexure strength, modulus (hybrid only), and fracture toughness were also reduced as the concentration of HDPE increased. SEM showed evidence for HDPE debonding and plastic deformation during fracture of the hybrid composites. In conclusion, the addition of HDPE spheres reduces contraction stress in composites, either through stress relief or a reduction in elastic modulus. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 318-323, 2003

Kinetics and mechanics of photo-polymerized triazole-containing thermosetting composites via the copper(I)-catalyzed azide-alkyne cycloaddition.

PubMed

Song, Han Byul; Wang, Xiance; Patton, James R; Stansbury, Jeffrey W; Bowman, Christopher N

2017-06-01

Several features necessary for polymer composite materials in practical applications such as dental restorative materials were investigated in photo-curable CuAAC (copper(I)-catalyzed azide-alkyne cycloaddition) thermosetting resin-based composites with varying filler loadings and compared to a conventional BisGMA/TEGDMA based composite. Tri-functional alkyne and di-functional azide monomers were synthesized for CuAAC resins and incorporated with alkyne-functionalized glass microfillers for CuAAC composites. Polymerization kinetics, in situ temperature change, and shrinkage stress were monitored simultaneously with a tensometer coupled with FTIR spectroscopy and a data-logging thermocouple. The glass transition temperature was analyzed by dynamic mechanical analysis. Flexural modulus/strength and flexural toughness were characterized in three-point bending on a universal testing machine. The photo-CuAAC polymerization of composites containing between 0 and 60wt% microfiller achieved ∼99% conversion with a dramatic reduction in the maximum heat of reaction (∼20°C decrease) for the 60wt% filled CuAAC composites as compared with the unfilled CuAAC resin. CuAAC composites with 60wt% microfiller generated more than twice lower shrinkage stress of 0.43±0.01MPa, equivalent flexural modulus of 6.1±0.7GPa, equivalent flexural strength of 107±9MPa, and more than 10 times higher energy absorption of 10±1MJm -3 when strained to 11% relative to BisGMA-based composites at equivalent filler loadings. Mechanically robust and highly tough, photo-polymerized CuAAC composites with reduced shrinkage stress and a modest reaction exotherm were generated and resulted in essentially complete conversion. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Polymerization kinetics of experimental bioactive composites containing bioactive glass.

PubMed

Par, Matej; Tarle, Zrinka; Hickel, Reinhard; Ilie, Nicoleta

2018-06-21

To investigate the polymerization kinetics and the degree of conversion (DC) of experimental resin composites with varying amount of bioactive glass 45S5 (BG). Experimental resin composites based on a photo-curable Bis-GMA/TEGDMA resin system were prepared. The composite series contained 0, 5, 10, 20, and 40 wt% of BG and reinforcing fillers up to the total filler amount of 70 wt%. Composite specimens were light cured with 1,219 mW/cm 2 for 20 or 40 s and their DC was monitored during 5 min at the data collection rate of 2 s -1 using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The 5-min DC values for experimental composites were in the range of 42.4-55.9% and 47.3-57.9% for curing times of 20 and 40 s, respectively. The differences in the 5-min DC between curing times of 20 s or 40 s became more pronounced in materials with higher BG amount. Within both curing times, a decreasing trend of the 5-min DC values was observed with the increasing percentage of BG fillers. The maximum polymerization rate also decreased consistently with the increasing BG amount. Unsilanized BG fillers showed a dose-dependent inhibitory effect on polymerization rate and the DC. Extending the curing time from 20 to 40 s showed a limited potential to improve the DC of composites with higher BG amount. The observed inhibitory effect of BG fillers on the polymerization of resin composites may have a negative influence on mechanical properties and biocompatibility. Copyright © 2018. Published by Elsevier Ltd.

Curing potential of experimental resin composites with systematically varying amount of bioactive glass: Degree of conversion, light transmittance and depth of cure.

PubMed

Par, Matej; Spanovic, Nika; Bjelovucic, Ruza; Skenderovic, Hrvoje; Gamulin, Ozren; Tarle, Zrinka

2018-06-17

The aim of this work was to investigate the curing potential of an experimental resin composite series with the systematically varying amount of bioactive glass 45S5 by evaluating the degree of conversion, light transmittance and depth of cure. Resin composites based on a Bis-GMA/TEGDMA resin with a total filler load of 70 wt% and a variable amount of bioactive glass (0-40 wt%) were prepared. The photoinitiator system was camphorquinone and ethyl-4-(dimethylamino) benzoate. The degree of conversion and light transmittance were measured by Raman spectroscopy and UV-vis spectroscopy, respectively. The depth of cure was evaluated according to the classical ISO 4049 test. The initial introduction of bioactive glass into the experimental series diminished the light transmittance while the further increase in the bioactive glass amount up to 40 wt% caused minor variations with no clear trend. The curing potential of the experimental composites was similar to or better than that of commercial resin composites. However, unsilanized bioactive glass fillers demonstrated the tendency to diminish both the maximum attainable conversion and the curing efficiency at depth. Experimental composite materials containing bioactive glass showed a clinically acceptable degree of conversion and depth of cure. The degree of conversion and depth of cure were diminished by bioactive glass fillers in a dose-dependent manner, although light transmittance was similar among all of the experimental composites containing 5-40 wt% of bioactive glass. Reduced curing potential caused by the bioactive glass has possible consequences on mechanical properties and biocompatibility. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of fracture toughness and mechanical properties of ternary thiol-ene-methacrylate systems as resin matrix for dental restorative composites.

PubMed

Beigi, Saeed; Yeganeh, Hamid; Atai, Mohammad

2013-07-01

Study and evaluation of fracture toughness, flexural and dynamic mechanical properties, and crosslink density of ternary thiol-ene-methacrylate systems and comparison with corresponding conventional methacrylate system were considered in the present study. Urethane tetra allyl ether monomer (UTAE) was synthesized as ene monomer. Different formulations were prepared based on combination of UTAE, BisGMA/TEGDMA and a tetrathiol monomer (PETMP). The photocuring reaction was conducted under visible light using BD/CQ combination as photoinitiator system. Mechanical properties were evaluated via measuring flexural strength, flexural modulus and fracture toughness. Scanning electron microscopy (SEM) was utilized to study the morphology of the fractured specimen's cross section. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). The same study was performed on a conventional methacrylate system. The data were analyzed and compared by ANOVA and Tukey HSD tests (significance level=0.05). The results showed improvement in fracture toughness of the specimens containing thiol-ene moieties. DMTA revealed a lower glass transition temperature and more homogenous structure for thiol-ene containing specimens in comparison to the system containing merely methacrylate monomer. The flexural modulus and flexural strength of the specimens with higher thiol-ene content were lower than the neat methacrylate system. The SEM micrographs of the fractured surface of specimens with higher methacrylate content were smooth and mirror-like (shiny) which represent brittle fracture. The thiol-ene-methacrylate system can be used as resin matrix of dental composites with enhanced fracture toughness in comparison to the methacrylate analogous. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites

PubMed Central

Zhang, Fan; Allen, Andrew J.; Levine, Lyle E.; Vaudin, Mark D.; Skrtic, Drago; Antonucci, Joseph M.; Hoffman, Kathleen M.; Giuseppetti, Anthony A.; Ilavsky, Jan

2014-01-01

Objective To investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP) -to-apatite transition in ACP based dental composite materials. Methods Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.6 mass fraction). We performed an investigation of the solution-mediated ACP-to-apatite conversion mechanism in controlled acidic aqueous environment with in situ ultra-small angle X-ray scattering based coherent X-ray photon correlation spectroscopy and ex situ X-ray diffraction, as well as other complementary techniques. Results We established that the ACP-to-apatite conversion in ACP composites is a two-step process, owing to the sensitivity to local structural changes provided by coherent X-rays. Initially, ACP undergoes a local microstructural rearrangement without losing its amorphous character. We established the catalytic role of the acid and found the time scale of this rearrangement strongly depends on the pH of the solution, which agrees with previous findings about ACP without the polymer matrix being present. In the second step, ACP is converted to an apatitic form with the crystallinity of the formed crystallites being poor. Separately, we also confirmed that in the regular Zr-modified ACP the rate of ACP conversion to hydroxyapatite is slowed significantly compared to unmodified ACP, which is beneficial for targeted slow release of functional calcium and phosphate ions from dental composite materials. Significance For the first time, we were able to follow the complete solution-mediated transition process from ACP to apatite in this class of dental composites in a controlled aqueous environment. A two-step process, suggested previously, was conclusively identified. PMID:25082155

Ammonium sensing in aqueous solutions with plastic optical fiber modified by molecular imprinting

NASA Astrophysics Data System (ADS)

Sequeira, F.; Duarte, D.; Rudnitskaya, A.; Gomes, M. T. S. R.; Nogueira, R.; Bilro, L.

2016-05-01

We report the development of a low cost plastic optical fibre (POF) sensor for ammonium detection using molecularly imprinted polymers (MIP's). The cladding of a 1 mm diameter PMMA fiber is removed, in which is grafted a molecular imprinted polymer (MIP), by radical polymerization with thermal initiation, that act as a selective sensing layer. For the polymerization, 2,2'-Azobis(2-methylpropionamidine)dihydrochloride (AAPH) is used as initiator, methacrylic acid (MAA) as a monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, ammonium chloride (NH4Cl) as a template and 30% of ethanol in water as a solvent. The sensing method consists of an intensity based scheme. The response to different concentrations of ammonium solutions in water has been evaluated at room temperature. Solutions with (0 - 0.6) M concentration, with the corresponding refractive indexes varying between 1.3325 - 1.3387, at 25°C were used. The response of the fiber with the original cladding, and after cladding removal has been monitored and compared to the response given by the developed sensor. The response is very fast, less than 1 minute and reversible, which allows the continuum use of the sensor. Further developments are focused in optimization of MIP grafting procedure and sensor performance, in order to increase sensitivity.

Porous polymer monolithic columns with gold nanoparticles as an intermediate ligand for the separation of proteins in reverse phase-ion exchange mixed mode

DOE PAGES

Terborg, Lydia; Masini, Jorge C.; Lin, Michelle; ...

2014-11-04

A new approach has been developed for the preparation of mixed-mode stationary phases to separate proteins. The pore surface of monolithic poly(glycidyl methacrylate- co-ethylene dimethacrylate) capillary columns was functionalized with thiols and coated with gold nanoparticles. The final mixed mode surface chemistry was formed by attaching, in a single step, alkanethiols, mercaptoalkanoic acids, and their mixtures on the free surface of attached gold nanoparticles. Use of these mixtures allowed fine tuning of the hydrophobic/hydrophilic balance. The amount of attached gold nanoparticles according to thermal gravimetric analysis was 44.8 wt.%. This value together with results of frontal elution enabled calculation ofmore » surface coverage with the alkanethiol and mercaptoalkanoic acid ligands. Interestingly, alkanethiols coverage in a range of 4.46–4.51 molecules/nm 2 significantly exceeded that of mercaptoalkanoic acids with 2.39–2.45 molecules/nm 2. The mixed mode character of these monolithic stationary phases was for the first time demonstrated in the separations of proteins that could be achieved in the same column using gradient elution conditions typical of reverse phase (using gradient of acetonitrile in water) and ion exchange chromatographic modes (applying gradient of salt in water), respectively.« less

FRET Imaging in Three-dimensional Hydrogels

PubMed Central

Taboas, Juan M.

2016-01-01

Imaging of Förster resonance energy transfer (FRET) is a powerful tool for examining cell biology in real-time. Studies utilizing FRET commonly employ two-dimensional (2D) culture, which does not mimic the three-dimensional (3D) cellular microenvironment. A method to perform quenched emission FRET imaging using conventional widefield epifluorescence microscopy of cells within a 3D hydrogel environment is presented. Here an analysis method for ratiometric FRET probes that yields linear ratios over the probe activation range is described. Measurement of intracellular cyclic adenosine monophosphate (cAMP) levels is demonstrated in chondrocytes under forskolin stimulation using a probe for EPAC1 activation (ICUE1) and the ability to detect differences in cAMP signaling dependent on hydrogel material type, herein a photocrosslinking hydrogel (PC-gel, polyethylene glycol dimethacrylate) and a thermoresponsive hydrogel (TR-gel). Compared with 2D FRET methods, this method requires little additional work. Laboratories already utilizing FRET imaging in 2D can easily adopt this method to perform cellular studies in a 3D microenvironment. It can further be applied to high throughput drug screening in engineered 3D microtissues. Additionally, it is compatible with other forms of FRET imaging, such as anisotropy measurement and fluorescence lifetime imaging (FLIM), and with advanced microscopy platforms using confocal, pulsed, or modulated illumination. PMID:27500354

One-pot preparation of a sulfamethoxazole functionalized affinity monolithic column for selective isolation and purification of trypsin.

PubMed

Xiao, Yuan; Guo, Jialiang; Ran, Danni; Duan, Qianqian; Crommen, Jacques; Jiang, Zhengjin

2015-06-26

A facile and efficient "one-pot" copolymerization strategy was used for the preparation of sulfonamide drug (SA) functionalized monolithic columns. Two novel SA-immobilized methacrylate monolithic columns, i.e. poly(GMA-SMX-co-EDMA) and poly(GMA-SAA-co-EDMA) were prepared by one-pot in situ copolymerization of the drug ligand (sulfamethoxazole (SMX) or sulfanilamide (SAA)), the monomer (glycidyl methacrylate, GMA) and the cross-linker (ethylene dimethacrylate, EDMA) within 100 μm i.d. capillaries under optimized polymerization conditions. The physicochemical properties and column performance of the fabricated monolithic columns were characterized by elemental analysis, scanning electron microscopy and micro-HPLC. Satisfactory column permeability, efficiency and separation performance were obtained on the optimized poly(GMA-SMX-co-EDMA) monolithic column for small molecules, such as a standard test mixture and eight aromatic ketones. Notably, it was found that the poly(GMA-SMX-co-EDMA) monolith showed a selective affinity to trypsin, while the poly(GMA-SAA-co-EDMA) monolith containing sulfanilamide did not exhibit such affinity at all. This research not only provides a novel monolith for the selective isolation and purification of trypsin, but it also offers the possibility to easily prepare novel drug functionalized methacrylate monoliths through a one-pot copolymerization strategy. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and application of ion-imprinted polymer nanoparticles for the extraction and preconcentration of copper ions in environmental water samples.

PubMed

Roushani, Mahmoud; Abbasi, Shahryar; Khani, Hossein

2015-04-01

Novel Cu(II) ion-imprinted polymers (Cu-IIP) nanoparticles were prepared by using Cu(II) ion-thiosemicarbazide complex as the template molecule and methacrylic acid, ethylene glycol dimethacrylate (EGDMA), and 2,2'azobisisobutyronitrile (AIBN) as the functional monomer, cross-linker, and the radical initiator, respectively. The synthesized polymer nanoparticles were characterized by using infrared spectroscopy (IR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopic (SEM) techniques. Some parameters such as pH, weight of the polymer, adsorption time, elution time, eluent type, and eluent volume which affect the extraction efficiency of the polymer were studied. In the proposed method, the maximum sorbent capacity of the ion-imprinted polymer was calculated to be 38.8 mg g(-1). The preconcentration factor, relative standard deviation, and limit of detection of the method were found to be 80, 1.7%, and 0.003 μg mL(-1), respectively. The prepared ion-imprinted polymer nanoparticles have an increased selectivity toward Cu(II) ions over a range of competing metal ions with the same charge and similar ionic radius. The method was applied to the determination of ultra trace levels of Cu2+ in environmental water samples with satisfactory results.

One-pot polymerization of monolith coated stir bar for high efficient sorptive extraction of perfluoroalkyl acids from environmental water samples followed by high performance liquid chromatography-electrospray tandem mass spectrometry detection.

PubMed

Yao, Xuezi; Zhou, Zhen; He, Man; Chen, Beibei; Liang, Yong; Hu, Bin

2018-06-08

In this work, poly(1-vinylimidazole-ethyleneglycol dimethacrylate) (poly(VI-EDMA)) monolith coated stir bars were synthesized by one-pot polymerization, and they exhibited higher extraction efficiency and faster extraction dynamics for selected PFAAs than commercial ethylene glycol modified silicone (EG-silicone) and polydimethylsiloxane (PDMS) coated stir bars. Taking eleven PFAAs as target analytes, including C4-C12 perfluoroalkyl carboxylates (PFCAs) and C6, C8 perfluoroalkane sulfonates (PFSAs), a method combining monolith-based stir bar sorptive extraction (SBSE) with high performance liquid chromatography (HPLC) - electrospray tandem mass spectrometry (ESI-MS/MS) was proposed for the determination of multiplex PFAAs in environmental water samples. Under the optimized conditions, low limits of detection (0.06-0.40 ng/L) and wide linear range (0.6-400 ng/L) were obtained for target PFAAs with. The developed method was then applied for the analysis of target PFAAs in environmental water samples, and recoveries of 80.1-117% and 80.3-122% were obtained for target PFAAs in spiked Yangtze River and East Lake water samples respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation and application of epitope magnetic molecularly imprinted polymers for enrichment of sulfonamide antibiotics in water.

PubMed

Hu, Yufeng; Wang, Cheng; Li, Xiangdao; Liu, Lifen

2017-10-01

Sulfonamides, which are widely used synthetic antibiotics, are hydrophilic and stable. They can easily migrate into the environment and aquatic animals, and increase the risk of cancer, drug resistance, and allergic symptoms if consumed by humans. Here, we developed an epitope magnetic imprinting approach to enrich multiple sulfonamide antibiotics from a water sample. Epitope magnetic molecularly imprinted polymers (EMMIPs) were prepared by free-radical polymerization using vinyl-functioned Fe 3 O 4 as a core, sulfanilamide (SA) as a dummy template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linker. The performance of the EMMIPs was first evaluated by rebinding SA, and then an adsorption experiment was conducted to assess the extraction of multiple sulfonamide antibiotics containing the SA group. The binding experiments showed that the EMMIPs reached adsorption equilibrium in only 5 min with adsorption of SA at 2040 μg/g, compared with just 462 μg/g for the epitope magnetic non-imprinted polymers. EMMIPs were combined with HPLC for the detection of six sulfonamide antibiotics in surface water samples. The recoveries ranged from 79.3 to 92.4% and the relative standard deviations from 0.9 to 7.3%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Salivary contamination during bonding procedures with a one-bottle adhesive system.

PubMed

Fritz, U B; Finger, W J; Stean, H

1998-09-01

The effect of salivary contamination of enamel and dentin on bonding efficacy of an experimental one-bottle resin adhesive was investigated. The adhesive was a light-curing urethane dimethacrylate/hydroxyethyl methacrylate/4-methacryloxyethyl trimellitate anhydride mixture dissolved in acetone. Evaluation parameters were shear bond strength and marginal gap width in a dental cavity. Apart from a control group without contamination (group 1), etched enamel and dentin were (2) contaminated with saliva and air dried; (3) contaminated, rinsed, and blot dried; (4) coated with adhesive, contaminated, rinsed, and blot dried; (5) coated with adhesive, light cured, contaminated, rinsed, and air dried; or (6) treated as in group 5, with additional adhesive application after air drying. There was no negative effect in groups 3 and 4, compared with control. Air drying after salivary contamination (group 2) resulted in low shear bond strengths and wide marginal gaps. Contamination of the cured adhesive layer (groups 5 and 6) had no adverse effect on enamel shear bond strengths, but resulted in 50% reduced dentin shear bond strengths and wide marginal gaps. The one-bottle adhesive system is relatively insensitive to salivary contamination, provided that the contamination occurs prior to light curing of the adhesive and is carefully rinsed and blot dried. Salivary contact after adhesive curing must be avoided.

Molecularly imprinted polymer cartridges coupled on-line with high performance liquid chromatography for simple and rapid analysis of dextromethorphan in human plasma samples.

PubMed

Moein, Mohammad Mahdi; Javanbakht, Mehran; Akbari-Adergani, Behrouz

2011-04-01

In this paper, a novel method is described for automated determination of dextromethorphan in biological fluids using molecularly imprinted solid-phase extraction (MISPE) as a sample clean-up technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and dextromethorphan as template molecule. These imprinted polymers were used as solid-phase extraction sorbent for the extraction of dextromethorphan from human plasma samples. Various parameters affecting the extraction efficiency of the MIP cartridges were evaluated. The high selectivity of the sorbent coupled to the high performance liquid chromatographic system permitted a simple and rapid analysis of this drug in plasma samples with limits of detection (LOD) and quantification (LOQ) of 0.12 ng/mL and 0.35 ng/mL, respectively. The MIP selectivity was evaluated by analyzing of the dextromethorphan in presence of several substances with similar molecular structures and properties. Results from the HPLC analyses showed that the recoveries of dextromethorphan using MIP cartridges from human plasma samples in the range of 1-50 ng/mL were higher than 87%. Copyright © 2011 Elsevier B.V. All rights reserved.

Polyethylene oxide-polytetrahydrofurane-PEDOT conducting interpenetrating polymer networks for high speed actuators

NASA Astrophysics Data System (ADS)

Plesse, C.; Khaldi, A.; Wang, Q.; Cattan, E.; Teyssié, D.; Chevrot, C.; Vidal, F.

2011-12-01

In recent years, numerous studies on electro-active polymer (EAP) actuators have been reported. One promising technology is the elaboration of electronic conducting polymer-based actuators with interpenetrating polymer network (IPNs) architecture. In this study, the synthesis and characterisation of conducting IPNs for actuator applications is described. The IPNs are synthesised from polyethylene oxide (PEO) and polytetrahydrofurane (PTHF) networks in which the conducting polymer (poly(3,4-ethylenedioxythiophene)) is incorporated. In a first step, PEO/PTHF IPNs were prepared via an 'in situ' process using poly(ethylene glycol) methacrylate and dimethacrylate and hydroxytelechelic PTHF as starting materials. The IPN mechanical properties were examined by DMA and tensile strength tests. N-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) swollen PEO/PTHF IPNs show ionic conductivities up to 10-3 S cm-1 at 30 °C. In a second step, the conducting IPN actuators were prepared by oxidative polymerisation of 3,4-ethylenedioxithiophene (EDOT) using FeCl3 as an oxidising agent within the PEO/PTHF IPN host matrix. The frequency response performance of the bending conducting IPN actuator was then evaluated. The resulting actuator exhibits a mechanical resonance frequency of up to 125 Hz with 0.75% strain for an applied potential of ± 5 V.

New synthesis method for 4-MAPBA monomer and using for the recognition of IgM and mannose with MIP-based QCM sensors.

PubMed

Diltemiz, Sibel Emir; Hür, Deniz; Keçili, Rüstem; Ersöz, Arzu; Say, Rıdvan

2013-03-07

Quartz crystal microbalance (QCM) sensors coated with molecularly imprinted polymers (MIP) have been developed for the recognition of immunoglobulin M (IgM) and mannose. In this method, methacryloylamidophenylboronic acid (MAPBA) was used as a monomer and mannose was used as a template. For this purpose, initially, QCM electrodes were modified with 2-propene-1-thiol to form mannose-binding regions on the QCM sensor surface. In the second step, the methacryloylamidophenylboronic acid-mannose [MAPBA-mannose], pre-organized monomer system, was prepared using the MAPBA monomer. Then, a molecularly imprinted film was coated on to the QCM electrode surface under UV light using ethylene glycol dimethacrylate (EDMA), and azobisisobutyronitrile (AIBN) as a cross-linking agent and an initiator, respectively. The mannose can be simultaneously bound to MAPBA and fitted into the shape-selective cavities. The binding affinity of the mannose-imprinted sensors was investigated using the Langmuir isotherm. The mannose-imprinted QCM electrodes have shown homogeneous binding sites for mannose (K(a): 3.3 × 10(4) M(-1)) and heterogeneous binding sites for IgM (K(a1): 1.0 × 10(4) M(-1); K(a2): 3.3 × 10(3) M(-1)).

Fabrication of an ionic-liquid-based polymer monolithic column and its application in the fractionation of proteins from complex biosamples.

PubMed

Zhang, Doudou; Zhang, Qian; Bai, Ligai; Han, Dandan; Liu, Haiyan; Yan, Hongyuan

2018-05-01

An ionic-liquid-based polymer monolithic column was synthesized by free radical polymerization within the confines of a stainless-steel column (50 mm × 4.6 mm id). In the processes, ionic liquid and stearyl methacrylate were used as dual monomers, ethylene glycol dimethacrylate as the cross-linking agent, and polyethylene glycol 200 and isopropanol as co-porogens. Effects of the prepolymerization solution components on the properties of the resulting monoliths were studied in detail. Scanning electron microscopy, nitrogen adsorption-desorption measurements, and mercury intrusion porosimetry were used to investigate the morphology and pore size distribution of the prepared monoliths, which showed that the homemade ionic-liquid-based monolith column possessed a relatively uniform macropore structure with a total macropore specific surface area of 44.72 m 2 /g. Compared to a non-ionic-liquid-based monolith prepared under the same conditions, the ionic-liquid-based monolith exhibited excellent selectivity and high performance for separating proteins from complex biosamples, such as egg white, snailase, bovine serum albumin digest solution, human plasma, etc., indicating promising applications in the fractionation and analysis of proteins from the complex biosamples in proteomics research. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CEC with new monolithic stationary phase based on a fluorinated monomer, trifluoroethyl methacrylate.

PubMed

Yurtsever, Arda; Saraçoğlu, Berna; Tuncel, Ali

2009-02-01

A new, fluorinated monolithic stationary phase for CEC was first synthesized by a single-stage, thermally initiated copolymerization of a fluorinated monomer, 2,2,2-trifluoroethyl methacrylate (TFEM) and ethylene dimethacrylate (EDMA) in the presence of a porogen mixture. In this preparation, 2-acrylamido-2-methyl-1-propanesulfonic acid was used as the charge-bearing monomer. The porogen mixture was prepared by mixing isoamylalcohol and 1,4-butanediol. A clear increase in the electroosmotic mobility was observed with increasing pH. The electroosmotic mobility decreased with increasing ACN concentration. Poly(TFEM-co-EDMA) monolith prepared under optimized polymerization conditions was successfully used in the separation of alkylbenzenes and phenols by CEC. The best chromatographic separation for alkylbenzenes was performed with lower ACN concentrations (i.e. 60% v/v) with respect to the common acrylic-based CEC monoliths. The theoretical plate numbers up to 220 000 plates/m were achieved in the reversed phase separation of phenols. Poly(TFEM-co-EDMA) monolith also allowed the simultaneous separation of aniline and benzoic acid derivatives by a single run and by using a lower ACN concentration in the mobile phase with respect to the similar electrochromatographic separations. A stable retention behaviour in reversed phase separation of alkylbenzenes was obtained with the poly(TFEM-co-EDMA) monolith.

Resin-Immobilized Palladium Nanoparticle Catalysts for Organic Reactions in Aqueous Media: Morphological Aspects.

PubMed

Mastrorilli, Piero; Dell'Anna, Maria M; Rizzuti, Antonino; Mali, Matilda; Zapparoli, Mauro; Leonelli, Cristina

2015-10-14

An insight into the nano- and micro-structural morphology of a polymer supported Pd catalyst employed in different catalytic reactions under green conditions is reported. The pre-catalyst was obtained by copolymerization of the metal-containing monomer Pd(AAEMA)₂ [AAEMA-=deprotonated form of 2-(acetoacetoxy) ethyl methacrylate] with ethyl methacrylate as co-monomer, and ethylene glycol dimethacrylate as cross-linker. This material was used in water for the Suzuki-Miyaura cross-coupling of aryl bromides, and for the reduction of nitroarenes and quinolines using NaBH₄ or H₂, as reductants. TEM analyses showed that in all cases the pristine Pd(II) species were reduced in situ to Pd(0), which formed metal nanoparticles (NPs, the real active species). The dependence of their average size (2-10 nm) and morphology on different parameters (temperature, reducing agent, presence of a phase transfer agent) is discussed. TEM and micro-IR analyses showed that the polymeric support retained its porosity and stability for several catalytic cycles in all reactions and Pd NPs did not aggregate after reuse. The metal nanoparticle distribution throughout the polymer matrix after several recycles provided precious information about the catalytic mechanism, which was truly heterogeneous in the hydrogenation reactions and of the so-called "release and catch" type in the Suzuki coupling.

Synthesis and characterization of core-shell magnetic molecularly imprinted polymers for solid-phase extraction and determination of Rhodamine B in food.

PubMed

Su, Xiaomeng; Li, Xiaoyan; Li, Junjie; Liu, Min; Lei, Fuhou; Tan, Xuecai; Li, Pengfei; Luo, Weiqiang

2015-03-15

Core-shell magnetic molecularly imprinted polymers (MIPs) nanoparticles (NPs), in which a Rhodamine B-imprinted layer was coated on Fe3O4 NPs. were synthesized. First, Fe3O4 NPs were prepared by a coprecipitation method. Then, amino-modified Fe3O4 NPs (Fe3O4@SiO2-NH2) was prepared. Finally, the MIPs were coated on the Fe3O4@SiO2-NH2 surface by the copolymerization with functional monomer, acrylamide, using a cross-linking agent, ethylene glycol dimethacrylate; an initiator, azobisisobutyronitrile and a template molecule, Rhodamine B. The Fe3O4@MIPs were characterized using a scanning electron microscope, Fourier transform infrared spectrometer, vibrating sample magnetometer, and re-binding experiments. The Fe3O4@MIPs showed a fast adsorption equilibrium, a highly improved imprinting capacity, and significant selectivity; they could be used as a solid-phase extraction material and detect illegal addition Rhodamine B in food. A method was developed for the selective isolation and enrichment of Rhodamine B in food samples with recoveries in the range 78.47-101.6% and the relative standard deviation was <2%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Patch test results of the dental personnel with contact dermatitis.

PubMed

Kocak, Oguzhan; Gul, Ulker

2014-12-01

Dental personnel have high risk of occupational contact dermatitis. The aim of this study is to detect the materials which cause contact sensitization and the frequency of contact dermatitis by using patch tests with European standard series and dental screening series in dental personnel. Between August 2008 and July 2009, 461 dental personnel working in Ankara (Turkey) were examined and age, gender, previous history of dermatitis, area of the skin affected and clinical diagnosis were noted. About 198 (43%) of the dental personnel were diagnosed contact dermatitis. Sixty-five of the dental personnel accepted to be patch tested. Dental technicians, dentists and dental nurses constitute 69.2%, 24.6% and 6.2% of patch tested 65 patients, respectively. Positive reactions to at least one allergen were detected with European standard series at 20% and with dental series at 10.8% among the dental personnel. The most common allergens were nickel sulfate (12.3%), acrylates (6.1%) and para-tertiary-butylphenol-formaldehyde resin (4.6%). The most common acrylate was ethyleneglycol dimethacrylate (3.1%). We believe our study will be helpful to dermatologists about frequency of contact dermatitis among dental personnel and allergens that cause contact sensitivity for developing new methods to protect the personnel in dentistry against sensitization.

Determination of malachite green in fish based on magnetic molecularly imprinted polymer extraction followed by electrochemiluminescence.

PubMed

Huang, Baomei; Zhou, Xibin; Chen, Jing; Wu, Guofan; Lu, Xiaoquan

2015-09-01

A novel procedure for selective extraction of malachite green (MG) from fish samples was set up by using magnetic molecularly imprinted polymers (MMIP) as the solid phase extraction material followed by electrochemiluminescence (ECL) determination. MMIP was prepared by using Fe3O4 magnetite as magnetic component, MG as template molecule, methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent. MMIP was characterized by SEM, TEM, FT-IR, VSM and XRD. Leucomalachite green (LMG) was oxidized in situ to MG by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). And then MMIP was successfully used to selectively enrich MG from fish samples. Adsorbed MG was desorbed and determined by ECL. Under the optimal conditions, calibration curve was good linear in the range of 0.29-290 μg/kg and the limit of detection (LOD) was 7.3 ng/kg (S/N=3). The recoveries of MMIP extraction were 77.1-101.2%. In addition, MMIP could be regenerated. To the best of our knowledge, MMIP coupling with ECL quenching of Ru(bpy)3(2+)/TPA for the determination of MG has not yet been developed. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs

PubMed Central

Bertassoni, Luiz E.; Cecconi, Martina; Manoharan, Vijayan; Nikkhah, Mehdi; Hjortnaes, Jesper; Cristino, Ana Luiza; Barabaschi, Giada; Demarchi, Danilo; Dokmeci, Mehmet R.; Yang, Yunzhi; Khademhosseini, Ali

2014-01-01

Vascularization remains a critical challenge in tissue engineering. The development of vascular networks within densely populated and metabolically functional tissues facilitate transport of nutrients and removal of waste products, thus preserving cellular viability over a long period of time. Despite tremendous progress in fabricating complex tissue constructs in the past few years, approaches for controlled vascularization within hydrogel based engineered tissue constructs have remained limited. Here, we report a three dimensional (3D) micromolding technique utilizing bioprinted agarose template fibers to fabricate microchannel networks with various architectural features within photo cross linkable hydrogel constructs. Using the proposed approach, we were able to successfully embed functional and perfusable microchannels inside methacrylated gelatin (GelMA), star poly (ethylene glycol-co-lactide) acrylate (SPELA), poly (ethylene glycol) dimethacrylate (PEGDMA) and poly (ethylene glycol) diacrylate (PEGDA) hydrogels at different concentrations. In particular, GelMA hydrogels were used as a model to demonstrate the functionality of the fabricated vascular networks in improving mass transport, cellular viability and differentiation within the cell-laden tissue constructs. In addition, successful formation of endothelial monolayers within the fabricated channels was confirmed. Overall, our proposed strategy represents an effective technique for vascularization of hydrogel constructs with useful applications in tissue engineering and organs on a chip. PMID:24860845

Radiation-induced change of optical property of hydroxypropyl cellulose hydrogel containing methacrylate compounds: As a basis for development of a new type of radiation dosimeter

NASA Astrophysics Data System (ADS)

Yamashita, Shinichi; Hiroki, Akihiro; Taguchi, Mitsumasa

2014-08-01

Hydrogels with matrix of a cellulose derivative, hydrogel of hydroxpropyl cellulose (HPC), containing two of methacrylate compounds (2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) dimethacrylate (9G)) were irradiated with 60Co γ-rays. The gels become white with irradiation, and thus, could be candidates of a new type of radiation dosimeter utilized in radiation therapy because the gels become white with irradiation and can be confirmed directly by human eyes even at low doses of 1-2 Gy. Radiation-induced change of optical properties, haze value and UV-vis absorption spectrum, of the irradiated gels was measured. Dose response of the white turbidity appearance was different for different compositions of the methacrylate compounds as well as for different dose rates. The degree of the radiation-induced white turbidity was quantified by measuring haze value, showing linear dose response in low dose region (<2 Gy). We also analyzed the gels with a UV-vis spectrometer and HEMA- and 9G-rich gels gave different spectral shapes, indicating that there are at least two mechanisms leading to the white turbidity. In addition, dose rate dependence was smaller for 9G-rich gels than HEMA-rich gels in the range of 0.015-1.5 Gy/min.

In vitro and in vivo evaluation of ketotifen fumarate-loaded silicone hydrogel contact lenses for ocular drug delivery.

PubMed

Xu, Jinku; Li, Xinsong; Sun, Fuqian

2011-02-01

The purpose of this work was to evaluate the usefulness of silicone hydrogel contact lenses loaded with ketotifen fumarate for ocular drug delivery. First, silicone contact lenses were prepared by photopolymerization of bitelechelic methacrylated polydimethylsiloxanes macromonomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, and N,N-dimethylacrylamide using ethylene glycol dimethacrylate as a cross-linker and Darocur 1173 as an initiator followed by surface plasma treatment. Then, the silicone hydrogel matrices of the contact lenses were characterized by equilibrium swelling ratio (ESR), tensile tests, ion permeability, and surface contact angle. Finally, the contact lenses were loaded with ketotifen fumarate by pre-soaking in drug solution to evaluate drug loading capacity, in vitro and in vivo release behavior of the silicone contact lenses. The results showed that ESR and ion permeability increase, and the surface contact angle and tensile strength decreased with the increase of DMA component in the silicone hydrogel. The drug loading and in vitro releases were dependent on the hydrogel composition of hydrophilic/hydrophobic phase of the contact lenses. In rabbit eyes, the pre-soaked contact lenses sustained ketotifen fumarate release for more than 24 h, which leads to a more stable drug concentration and a longer mean retention time in tear fluid than that of eye drops of 0.05%.

Shape Memory Polymers Containing Higher Acrylate Content Display Increased Endothelial Cell Attachment

PubMed Central

Govindarajan, Tina; Shandas, Robin

2018-01-01

Shape Memory Polymers (SMPs) are smart materials that can recall their shape upon the application of a stimulus, which makes them appealing materials for a variety of applications, especially in biomedical devices. Most prior SMP research has focused on tuning bulk properties; studying surface effects of SMPs may extend the use of these materials to blood-contacting applications, such as cardiovascular stents, where surfaces that support rapid endothelialization have been correlated to stent success. Here, we evaluate endothelial attachment onto the surfaces of a family of SMPs previously developed in our group that have shown promise for biomedical devices. Nine SMP formulations containing varying amounts of tert-Butyl acrylate (tBA) and Poly(ethylene glycol) dimethacrylate (PEGDMA) were analyzed for endothelial cell attachment. Dynamic mechanical analysis (DMA), contact angle studies, and atomic force microscopy (AFM) were used to verify bulk and surface properties of the SMPs. Human umbilical vein endothelial cell (HUVEC) attachment and viability was verified using fluorescent methods. Endothelial cells preferentially attached to SMPs with higher tBA content, which have rougher, more hydrophobic surfaces. HUVECs also displayed an increased metabolic activity on these high tBA SMPs over the course of the study. This class of SMPs may be promising candidates for next generation blood-contacting devices. PMID:29707382

Antibacterial Activity of Silver Nanoparticle-Loaded Soft Contact Lens Materials: The Effect of Monomer Composition.

PubMed

Shayani Rad, Maryam; Khameneh, Bahman; Sabeti, Zahra; Mohajeri, Seyed Ahmad; Fazly Bazzaz, Bibi Sedigheh

2016-10-01

In the present work, the effect of monomer composition on silver nanoparticles' (SNPs) binding capacity of hydrogels was investigated and their antibacterial efficacy was evaluated. Three series of poly-hydroxyethyl methacrylate (HEMA) hydrogels were prepared using methacrylic acid (MAA), methacrylamide (MAAM), and 4-vinylpyridine (4VP) as co-monomers, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. SNPs binding capacity of hydrogels was evaluated in different concentrations (2, 10, and 20 ppm). In vitro antibacterial activity of SNP-loaded hydrogels was studied against Pseudomonas aeruginosa (P. aeruginosa) isolated from patients' eyes. Then, inhibitory effect of hydrogels in biofilm formation was evaluated in the presence of Staphylococcus epidermidis (S. epidermidis) (DSMZ 3270). Our data indicated that poly(HEMA-co-MAA-co-EGDMA) had superior binding affinity for SNPs in comparison with other hydrogels. All SNP-loaded hydrogels demonstrated excellent antimicrobial effects at all times against P. aeruginosa and S. epidermidis after soaking in 10 and 20 ppm SNP suspensions. Scanning electron microscope (SEM) images revealed excellent inhibitory effect of SNPs against biofilm formation on the surface of the hydrogels. This study indicated the effect of monomer compositions in SNP loading capacity of poly(HEMA) hydrogels and antibacterial efficacy of SNP-loaded hydrogels against P. aeruginosa and S. epidermidis, but further in vivo evaluation is necessary.

Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

NASA Astrophysics Data System (ADS)

Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

2012-06-01

Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

A monolithic lipase reactor for biodiesel production by transesterification of triacylglycerides into fatty acid methyl esters

PubMed Central

Urban, Jiri; Svec, Frantisek; Fréchet, Jean M.J.

2011-01-01

An enzymatic reactor with lipase immobilized on a monolithic polymer support has been prepared and used to catalyze the transesterification of triacylglycerides into the fatty acid methyl esters commonly used for biodiesel. A design of experiments procedure was used to optimize the monolithic reactor with variables including control of the surface polarity of the monolith via variations in the length of the hydrocarbon chain in alkyl methacrylate monomer, time of grafting of 1-vinyl-4,4-dimethylazlactone used to activate the monolith, and time used for the immobilization of porcine lipase. Optimal conditions involved the use of a poly(stearyl methacrylate-co-ethylene dimethacrylate) monolith, grafted first with vinylazlactone, then treated with lipase for 2 h to carry out the immobilization of the enzyme. Best conditions for the transesterification of glyceryl tributyrate included a temperature of 37°C and a 10 min residence time of the substrate in the bioreactor. The reactor did not lose its activity even after pumping through it a solution of substrate equaling 1,000 reactor volumes. This enzymatic reactor was also used for the transesterification of triacylglycerides from soybean oil to fatty acid methyl esters thus demonstrating the ability of the reactor to produce biodiesel. PMID:21915852

A monolithic lipase reactor for biodiesel production by transesterification of triacylglycerides into fatty acid methyl esters.

PubMed

Urban, Jiri; Svec, Frantisek; Fréchet, Jean M J

2012-02-01

An enzymatic reactor with lipase immobilized on a monolithic polymer support has been prepared and used to catalyze the transesterification of triacylglycerides into the fatty acid methyl esters commonly used for biodiesel. A design of experiments procedure was used to optimize the monolithic reactor with variables including control of the surface polarity of the monolith via variations in the length of the hydrocarbon chain in alkyl methacrylate monomer, time of grafting of 1-vinyl-4,4-dimethylazlactone used to activate the monolith, and time used for the immobilization of porcine lipase. Optimal conditions involved the use of a poly(stearyl methacrylate-co-ethylene dimethacrylate) monolith, grafted first with vinylazlactone, then treated with lipase for 2 h to carry out the immobilization of the enzyme. Best conditions for the transesterification of glyceryl tributyrate included a temperature of 37°C and a 10 min residence time of the substrate in the bioreactor. The reactor did not lose its activity even after pumping through it a solution of substrate equaling 1,000 reactor volumes. This enzymatic reactor was also used for the transesterification of triacylglycerides from soybean oil to fatty acid methyl esters thus demonstrating the ability of the reactor to produce biodiesel. Copyright © 2011 Wiley Periodicals, Inc.

Improved properties of bone and cartilage tissue from 3D inkjet-bioprinted human mesenchymal stem cells by simultaneous deposition and photocrosslinking in PEG-GelMA.

PubMed

Gao, Guifang; Schilling, Arndt F; Hubbell, Karen; Yonezawa, Tomo; Truong, Danh; Hong, Yi; Dai, Guohao; Cui, Xiaofeng

2015-11-01

Bioprinting of bone and cartilage suffers from low mechanical properties. Here we have developed a unique inkjet bioprinting approach of creating mechanically strong bone and cartilage tissue constructs using poly(ethylene glycol) dimethacrylate, gelatin methacrylate, and human MSCs. The printed hMSCs were evenly distributed in the polymerized PEG-GelMA scaffold during layer-by-layer assembly. The procedure showed a good biocompatibility with >80% of the cells surviving the printing process and the resulting constructs provided strong mechanical support to the embedded cells. The printed mesenchymal stem cells showed an excellent osteogenic and chondrogenic differentiation capacity. Both osteogenic and chondrogenic differentiation as determined by specific gene and protein expression analysis (RUNX2, SP7, DLX5, ALPL, Col1A1, IBSP, BGLAP, SPP1, Col10A1, MMP13, SOX9, Col2A1, ACAN) was improved by PEG-GelMA in comparison to PEG alone. These observations were consistent with the histological evaluation. Inkjet bioprinted-hMSCs in simultaneously photocrosslinked PEG-GelMA hydrogel scaffolds demonstrated an improvement of mechanical properties and osteogenic and chondrogenic differentiation, suggesting its promising potential for usage in bone and cartilage tissue engineering.

Organic monolith frits encased in polyether ether ketone tubing with improved durability for liquid chromatography.

PubMed

Park, Sin Young; Cheong, Won Jo

2015-09-01

This study introduces a preparation method for polymer-encased monolith frits with improved durability for liquid chromatography columns. The inner surface of the polyether ether ketone tubing is pretreated with sulfuric acid in the presence of catalysts (vanadium oxide and sodium sulfate). The tubing was rinsed with water and acetone, flushed with nitrogen, and treated with glycidyl methacrylate. After washing, the monolith reaction mixture composed of lauryl methacrylate, ethylene glycol dimethacrylate, initiator, and porogenic solvent was filled in the tubing and subjected to in situ polymerization. The tubing was cut into thin slices and used as frits for microcolumns. To check their durability, the frit slices were placed in a vial and a heavy impact was applied on the vial by a vortex mixer for various periods. The frits made in the presence of catalysts were found to be more durable than those made without catalysts. Furthermore, when the monolith-incorporated tubing was used as a chromatography column, the column prepared in the presence of catalysts resulted in a better separation efficiency. The separation performance of the columns installed with the polyether ether ketone encased monolith frits was comparable to that of the columns installed with the commercial stainless-steel screen frits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biocompatibility Evaluation of Four Dentin Adhesives Used as Indirect Pulp Capping Materials

PubMed Central

Cortés, Olga; Bernabé, Antonia

2017-01-01

Background In many cases, the indirect pulp treatment (IPT) is an acceptable treatment for deciduous teeth with reversible pulp inflammation. Various medicaments have been used for IPT, ranging from calcium hydroxide and glass ionomers to dentin adhesives. Objective This in vitro trial aimed to measure cytotoxicity in a cell culture, comparing the following four adhesives: Xeno® V (XE), Excite® F DSC (EX), Adhese® OneF (AD) and Prime & Bond NT (PB). Materials and methods The adhesives were prepared according to the manufacturer’s instructions. After 24 hours of exposure, the cell viability was evaluated using a photometrical test (MTT test). Data were subjected to analysis of variance (ANOVA). Results Adhesives, the main component of which was 2-hydroxyethyl methacrylate (HEMA), were found to be less cytotoxic, while those that included the monomer urethane dimethacrylate (UDMA were the most cytotoxic) in their composition. The effects on cell viability assay varied between the adhesives assayed with statistically significant differences. Conclusions The results may support the argument that Adhese® OneF is the least cytotoxic of the adhesives assayed, and may be considered as an adhesive agent for indirect pulp treatment. However, Prime and Bond NT showed a reduced biocompatibility under the same conditions. PMID:28827848

Conducting polymer networks synthesized by photopolymerization-induced phase separation

NASA Astrophysics Data System (ADS)

Yamashita, Yuki; Komori, Kana; Murata, Tasuku; Nakanishi, Hideyuki; Norisuye, Tomohisa; Yamao, Takeshi; Tran-Cong-Miyata, Qui

2018-03-01

Polymer mixtures composed of double networks of a polystyrene derivative (PSAF) and poly(methyl methacrylate) (PMMA) were alternatively synthesized by using ultraviolet (UV) and visible (Vis) light. The PSAF networks were generated by UV irradiation to photodimerize the anthracene (A) moieties labeled on the PSAF chains, whereas PMMA networks were produced by photopolymerization of methyl methacrylate (MMA) monomer and the cross-link reaction using ethylene glycol dimethacrylate (EGDMA) under Vis light irradiation. It was found that phase separation process of these networks can be independently induced and promptly controlled by using UV and Vis light. The characteristic length scale distribution of the resulting co-continuous morphology can be well regulated by the UV and Vis light intensity. In order to confirm and utilize the connectivity of the bicontinuous morphology observed by confocal microscopy, a very small amount, 0.1 wt%, of multi-walled carbon nanotubes (MWCNTs) was introduced into the mixture and the current-voltage (I-V) relationship was subsequently examined. Preliminary data show that MWCNTs are preferentially dispersed in the PSAF-rich continuous domains and the whole mixture became electrically conducting, confirming the connectivity of the observed bi-continuous morphology. The experimental data obtained in this study reveal a promising method to design various scaffolds for conducting soft matter taking advantages of photopolymerization-induced phase separation.

Preparation of "dummy" l-phenylalanine molecularly imprinted microspheres by using ionic liquid as a template and functional monomer.

PubMed

Li, Ji; Hu, Xiaoling; Guan, Ping; Song, Dongmen; Qian, Liwei; Du, Chunbao; Song, Renyuan; Wang, Chaoli

2015-07-07

In this study, dummy imprinting technology was employed for the preparation of l-phenylalanine-imprinted microspheres. Ionic liquids were utilized as both a "dummy" template and functional monomer, and 4-vinylpyridine and ethylene glycol dimethacrylate were used as the assistant monomer and cross-linker, respectively, for preparing a surface-imprinted polymer on poly(divinylbenzene) microspheres. By the results obtained by theoretical investigation, the interaction between the template and monomer complex was improved as compared with that between the template and the traditional l-phenylalanine-imprinted polymer. The batch experiments indicated that the imprinting factor reached 2.5. Scatchard analysis demonstrated that the obtained "dummy" molecularly imprinted microspheres exhibited an affinity of 77.4 M·10 -4 , significantly higher that of a traditional polymer directly prepared by l-phenylalanine, which is in agreement with theoretical results. Competitive adsorption experiments also showed that the molecularly imprinted polymer with the dummy template effectively isolated l-phenylalanine from l-histidine and l-tryptophan with separation factors of 5.68 and 2.68, respectively. All these results demonstrated that the polymerizable ionic liquid as the dummy template could enhance the affinity and selectivity of molecularly imprinted polymer, thereby promoting the development of imprinting technology for biomolecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of the linking spacer length and type on the enantioseparation ability of β-cyclodextrin functionalized monoliths.

PubMed

Guo, Jialiang; Xiao, Yuan; Lin, Yuanjing; Zhang, Qiaoxuan; Chang, Yiqun; Crommen, Jacques; Jiang, Zhengjin

2016-05-15

In order to investigate the effect of the linking spacer on the enantioseparation ability of β-cyclodextrin (β-CD) functionalized polymeric monoliths, three β-CD-functionalized organic polymeric monoliths with different spacer lengths were prepared by using three amino-β-CDs, i.e. mono-6-amino-6-deoxy-β-CD, mono-6-ethylenediamine-6-deoxy-β-CD, mono-6-hexamethylenediamine-6-deoxy-β-CD, as starting materials. These amino-β-CDs reacted with glycidyl methacrylate to produce functional monomers which were then copolymerized with ethylene dimethacrylate. The enantioseparation ability of the three monoliths was evaluated using 14 chiral acidic compounds, including mandelic acid derivatives, nonsteroidal anti-inflammatory drugs, N-derivatized amino acids, and chiral herbicides under optimum chromatographic conditions. Notably, the poly(GMA-NH2-β-CD-co-EDMA) column provides higher enantioresolution and enantioselectivity than the poly(GMA-EDA-β-CD-co-EDMA) and poly(GMA-HDA-β-CD-co-EDMA) columns for most tested chiral analytes. Furthermore, the enantioseparation performance of triazole-linker containing monoliths was compared to that of ethylenediamine-linker containing monoliths. The results indicate that the enantioselectivity of β-CD monolithic columns is strongly related to the length and type of spacer tethering β-CD to the polymeric support. Copyright © 2016 Elsevier B.V. All rights reserved.

Allergic contact dermatitis caused by acrylic-based medical dressings and adhesives.

PubMed

Mestach, Lien; Huygens, Sara; Goossens, An; Gilissen, Liesbeth

2018-06-11

Acrylates and methacrylates are acrylic resin monomers that are known to induce skin sensitization as a result of their presence in different materials, such as nail cosmetics, dental materials, printing inks, and adhesives. Allergic contact dermatitis resulting from the use of modern wound dressings containing them has only rarely been reported. To describe 2 patients who developed allergic contact dermatitis caused by acrylic-based modern medical dressings and/or adhesives. The medical charts of patients observed since 1990 were retrospectively reviewed for (meth)acrylate allergy resulting from contact with such materials, and their demographic characteristics and patch test results were analysed. Two patients were observed in 2014 and 2016 who had presented with positive patch test reactions to several acrylic-based dressings and/or adhesive materials, and to several (meth)acrylates, that is, hydroxyethyl acrylate, hydroxyethyl methacrylate, ethyleneglycol dimethacrylate, bisphenol A-glycidyl methacrylate/epoxy-acrylate, urethane diacrylate, and/or penta-erythritol acrylate. Allergic contact dermatitis needs to be considered in patients with eczematous reactions or delayed healing following the use of acrylic-based modern dressings or adhesives. However, identification of the culprit allergen is hampered by poor cooperation from the producers, so adequate labelling of medical devices is an urgent necessity. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Molecularly imprinted polymer cartridges coupled to high performance liquid chromatography (HPLC-UV) for simple and rapid analysis of fenthion in olive oil.

PubMed

Bakas, Idriss; Ben Oujji, Najwa; Istamboulié, Georges; Piletsky, Sergey; Piletska, Elena; Ait-Addi, Elhabib; Ait-Ichou, Ihya; Noguer, Thierry; Rouillon, Régis

2014-07-01

A combination of molecular modelling and a screening of the library of non-imprinted polymers (NIPs) was used to identify acrylamide as a functional monomer with high affinity towards fenthion, organophosphate insecticide, which is frequently used in the treatment of olives. A good correlation was found between the screening tests and modelling of monomer-template interactions performed using a computational approach. Acrylamide-based molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were thermally synthesised in dimethyl formamide (porogen) using ethylene glycol dimethacrylate as a cross-linker and 1,1-azo-bis (isobutyronitrile) as an initiator. The chemical and physical properties of the prepared polymers were characterised. The binding of fenthion by the polymers was studied using solvents with different polarities. The developed MIP showed a high selectivity towards fenthion, compared to other organophosphates (dimethoate, methidathion malalthion), and allowed extraction of fenthion from olive oil samples with a recovery rate of about 96%. The extraction of fenthion using MIPs was much more effective than traditional C18 reverse-phase solid phase extraction and allowed to achieve a low detection limit (LOD) (5 µg L(-1)). Copyright © 2014 Elsevier B.V. All rights reserved.

Proton conducting gel polyelectrolytes based on 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) copolymers with polyfunctional monomers. Part I. Anhydrous systems

NASA Astrophysics Data System (ADS)

Zygadło-Monikowska, Ewa; Florjańczyk, Zbigniew; Wielgus-Barry, Edyta; Paśniewski, Jarosław

The synthesis of crosslinked gel polyelectrolytes in polar aprotic solvents such as dimethylformamide (DMF) and a DMF and propylene carbonate (PC) mixture has been carried out in the copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and polyfunctional monomers. N, N‧-Methylene-bis-acrylamide, trioxyethylene dimethacrylate (M n ∼ 330) and trimethylolpropane ethoxylate (14/3 EO/OH) triacrylate were used as crosslinking monomers. The reactions were initiated thermally or by UV irradiation in the presence of Irgacure 184 or methyl benzoin ether. The crosslinking monomer was used in an amount of 0.5-13 wt.%. The effect of the type and concentration of the polyfunctional comonomer and type of solvent on the optical (color, transparency) and mechanical properties as well as the ability to conduct electrical charges have been studied. The application of a DMF and PC mixture enables to obtain transparent systems of good mechanical properties and high ambient temperature ionic conductivity of the order of 10 -3 to 10 -4 S cm -1, slightly lowered as compared with that of gels comprising DMF alone. The conducting properties of crosslinked gels have been compared with that of the AMPSA homopolymer solutions in analogous solvents.

Application of molecular imprinted polymer nanoparticles as a selective solid phase extraction for preconcentration and trace determination of 2,4-dichlorophenoxyacetic acid in the human urine and different water samples.

PubMed

Omidi, Fariborz; Behbahani, Mohammad; Sadeghi Abandansari, Hamid; Sedighi, Alireza; Shahtaheri, Seyed Jamaleddin

2014-01-01

A molecular-imprinted polymer nanoparticles (MIP-NP) for the selective preconcentration of 2,4-dichlorophenoxyacetic acid (2,4-D) is described. It was obtained by precipitation polymerization from methacrylic acid (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2'-azobisisobutyronitrile (the initiator) and 2,4-D (the template molecule) in acetonitrile solution. The MIP-NPs were characterized by thermogravimetric analysis, and by scanning electron microscopy. Imprinted 2,4-D molecules were removed from the polymeric structure using acetic acid in methanol (15:85 v/v %) as the eluting solvent. The sorption and desorption process occur within 10 min and 15 min, respectively. The maximum sorbent capacity of the molecular imprinted polymer is 89.2 mg g(-1). The relative standard deviation and limit of detection for water samples by introduced selective solid phase extraction were 4.2% and 1.25 μg L(-1), and these data for urine samples were 4.7% and 1.80 μg L(-1), respectively. The method was applied to the determination of 2,4-D in the urine and different water samples.

Molecularly imprinted polymer doped with Hectorite for selective recognition of sinomenine hydrochloride.

PubMed

Zhang, W; Fu, H L; Li, X Y; Zhang, H; Wang, N; Li, W; Zhang, X X

2016-01-01

In this work, a new and facile method was introduced to prepare molecularly imprinted polymers (MIPs) based on nano clay hectorite (Hec) for sinomenine hydrochloride (SM) analysis. Hec was firstly dissolved in distilled water in order to swell adequately, followed by a common precipitation polymerization with SM as the template, methacrylic acid as monomer, ethylene glycol dimethacrylate as a crosslinker and 2,2-azobisisobutyronitrile as an initiator. Hec@SM-MIPs were characterized by Fourier transform infrared spectrometer, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The maximum binding capacity of Hec@SM-MIPs, SM-MIPs and non-imprinted polymers (NIPs) (Hec@NIPs) was 57.4, 16.8 and 11.6 mg/g, respectively. The reason for this result may be that Hec@SM-MIPs have more binding sites and imprinted cavities for template molecule. Equilibrium data were described by the Langmuir and Freundlich isotherm models. The results showed that the Hec@SM-MIPs adsorption data correlated better with the Langmuir equation than the Freundlich equation under the studied concentration range. In vitro drug release experiment, Hec@SM-MIPs have a better ability to control SM release than SM-MIPs. Therefore, Hec@SM-MIPs were successfully applied to extraction of SM and used as the materials for drug delivery system.

Selective extraction of derivates of p-hydroxy-benzoic acid from plant material by using a molecularly imprinted polymer.

PubMed

Karasová, Gabriela; Lehotay, Jozef; Sádecká, Jana; Skacáni, Ivan; Lachová, Miroslava

2005-12-01

Selective SPE of derivates of p-hydroxybenzoic acid (pHBA) from plant extract of Melissa officinalis is presented using a molecularly imprinted polymer (MIP) made with protocatechuic acid (PA) as template molecule. MIP was prepared with acrylamide as functional monomer, ethylene glycol dimethacrylate as crosslinking monomer and ACN as porogen. MIP was evaluated towards six phenolic acids: PA, gallic acid, pHBA, vanillic acid (VA), gentisic acid (GeA) and syringic acid (SyrA), and then steps of molecularly imprinted SPE (MISPE) procedure were optimized. The best specific binding capacity of MIP was obtained for PA in ACN (34.7 microg/g of MIP). Other tested acids were also bound on MIP if they were dissolved in this solvent. ACN was chosen as solvent for sample application. M. officinalis was extracted into methanol/water (4:1, v/v), the extract was then evaporated to dryness and dissolved in ACN before application on MIP. Water and ACN were used as washing solvents and elution of benzoic acids was performed by means of a mixture methanol/acetic acid (9:1, v/v). pHBA, GA, PA and VA were extracted with recoveries of 56.3-82.1% using this MISPE method. GeA was not determined in plant extract.

Mechanism of molecular recognition on molecular imprinted monolith by capillary electrochromatography.

PubMed

Liu, Zhao-Sheng; Xu, Yan-Li; Yan, Chao; Gao, Ru-Yu

2005-09-16

The recognition mechanism of molecularly imprinted polymer (MIP) in capillary electrochromatography (CEC) is complicated since it possesses a hybrid process, which comprises the features of chromatographic retention, electrophoretic migration and molecular imprinting. For an understanding of the molecular recognition of MIP in CEC, a monolithic MIP in a capillary with 1,1'-binaphthyl-2,2'-diamine (BNA) imprinting was prepared by in situ copolymerization of imprinted molecule, methacrylic acid and ethylene glycol dimethacrylate in porogenic solvent, a mixture of toluene-isooctane. Strong recognition ability and high column performance (theory plates was 43,000 plates/m) of BNA were achieved on this monolithic MIP in CEC mode. In addition, BNA and its structural analogue, 1,1'-bi-2, 2'-naphthol, differing in functional groups, were used as model compounds to study imprinting effect on the resultant BNA-imprinted monolithic column, a reference column without imprinting of BNA and a open capillary. The effects of organic modifier concentration, pH value of buffer, salt concentration of buffer and column temperature on the retention and recognition of two compounds were investigated. The results showed that the molecular recognition on MIP monolith in CEC mode mainly derived from imprinting cavities on BNA-imprinted polymer other than chromatographic retention and electrophoretic migration.

Determination of benzimidazole anthelmintics in milk and honey by monolithic fiber-based solid-phase microextraction combined with high-performance liquid chromatography-diode array detection.

PubMed

Zhang, Yong; Huang, Xiaojia; Yuan, Dongxing

2015-01-01

A porous poly(methacrylic acid-co-ethylene dimethacrylate) monolithic fiber (MEMF) for solid-phase microextraction (SPME) of five benzimidazole anthelmintics was prepared by in-situ polymerization. The effect of polymerization conditions on SPME of the target analytes was studied thoroughly. The physicochemical properties of the monolith were characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy, and mercury intrusion porosimetry. Several conditions affecting the extraction efficiency were investigated and, under the optimized conditions, a simple and sensitive method for the determination of trace benzimidazoles residues in milk and honey was established by coupling MEMF-SPME with high-performance liquid chromatography-diode array detection (MEMF-SPME-HPLC-DAD). Under the optimum experimental conditions, the limits of detection (S/N = 3) of the method were 0.11-0.30 μg L(-1) for milk and 0.086-0.28 μg L(-1) for honey. Evaluation of intra-day and inter-day precision showed reproducibility was satisfactory-relative standard deviations (RSD) for both were <10 %. Finally, the method was successfully used for determination of benzimidazole residues in milk and honey. Recoveries obtained for determination of benzimidazole anthelmintics in spiked samples ranged from 72.3 to 121 %, with RSD always <11 %.

Thermal preparation of lysozyme-imprinted microspheres by using ionic liquid as a stabilizer.

PubMed

Qian, Li-Wei; Hu, Xiao-Ling; Guan, Ping; Gao, Bo; Wang, Dan; Wang, Chao-Li; Li, Ji; Du, Chun-Bao; Song, Wen-Qi

2014-11-01

Thermal preparation of lysozyme-imprinted microspheres was firstly investigated by using biocompatible ionic liquid (IL) as a thermal stabilizer. The imprinted microspheres made with IL could obtain the good recognition ability to template protein, whereas the imprinted polymer synthesized in the absence of it had a similar adsorption capacity to the non-imprinted one. Furthermore, the preparation conditions of imprinted polymers (MIPs) including the content of IL, temperature of polymerization, and types of functional monomers and crosslinkers were systematically analyzed via circular dichroism spectrum and activity assay. The results illustrated that using hydroxyethyl acrylate as the functional monomer, ethylene glycol dimethacrylate as the crosslinker, 5 % IL as the stabilizer, and 75 °C as the reaction temperature could retain the structure of template protein as much as possible. The obtained MIPs showed excellent recognition ability to the template protein with the separation factor and selectivity factor value of 4.30 and 2.21, respectively. Consequently, it is an effective way to accurately imprint and separate template protein by cooperatively using circular dichroism spectroscopy and activity assay during the preparation of protein MIPs. The method of utilizing IL to stabilizing protein at high temperature would offer a good opportunity for various technologies to improve the development of macromolecules imprinting.

Synthesis of molecular imprinted polymers for selective extraction of domperidone from human serum using high performance liquid chromatography with fluorescence detection.

PubMed

Salehi, Simin; Rasoul-Amini, Sara; Adib, Noushin; Shekarchi, Maryam

2016-08-01

In this study a novel method is described for selective quantization of domperidone in biological matrices applying molecular imprinted polymers (MIPs) as a sample clean up procedure using high performance liquid chromatography coupled with a fluorescence detector. MIPs were synthesized with chloroform as the porogen, ethylene glycol dimethacrylate as the crosslinker, methacrylic acid as the monomer, and domperidone as the template molecule. The new imprinted polymer was used as a molecular sorbent for separation of domperidone from serum. Molecular recognition properties, binding capacity and selectivity of MIPs were determined. The results demonstrated exceptional affinity for domperidone in biological fluids. The domperidone analytical method using MIPs was verified according to validation parameters, such as selectivity, linearity (5-80ng/mL, r(2)=0.9977), precision and accuracy (10-40ng/mL, intra-day=1.7-5.1%, inter-day=4.5-5.9%, and accuracy 89.07-98.9%).The limit of detection (LOD) and quantization (LOQ) of domperidone was 0.0279 and 0.092ng/mL, respectively. The simplicity and suitable validation parameters makes this a highly valuable selective bioequivalence method for domperidone analysis in human serum. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis, Characterization and Performance of Cathodes for Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Zhu, Jianxin

Lithium ion batteries provide a high energy density, higher voltage as well as a long shelf life compared to traditionally used lead acid, NiMH and NiCd batteries. Thus, they are a very promising energy storage system for our daily life. As one of the most important components in a battery, cathode materials have been investigated intensively in recent years as they play a key role in determining the cell voltage and discharge capacity in a battery. Both layered Li(Ni1/3Co1/3Mn1/3)O 2 (NCM) and olivine-structured LiFePO4 (LFP) materials are promising cathode candidates. However, these cathodes also have some disadvantages that have hindered further commercialization. The main issue with NCM is its rapid performance decay upon cycling. In addition, LFP is hindered by a low rate capacity and low lithium ion diffusivity. We studied the crystal growth behavior and performance of both Li(Ni 1/3Co1/3Mn1/3)O2 and LiFePO4 cathodes in order to develop synthesis-structure-function relationships. Three different crystal growth behaviors were observed for the NCM annealing process: surface, volume and grain boundary diffusion. Further exploration of the mechanism of NCM performance decay revealed that microstructural changes were related to the strain accommodation ability in this system and that nanostructured materials were more stable during cycling. In the LFP synthesis, we observed both oriented attachment (OA) and Ostwald ripening (OR) during growth in a triethylene-glycol system. Both polycrystalline and single crystalline particles evolved as a function of a time-dependent pH change. Thus, the lithium ion diffusion rate of LiFePO4 was improved by tailoring the morphology and size though our modification of the precursor environment, revealing that polycrystalline LFP displayed better performance than single crystalline particles. Finally, the electronic conductivity of LiFePO4 was successfully increased via a polymer solution coating method. By producing more uniform, thin and coherent coatings on LiFePO4 particles, we were able to produce batteries with significantly less carbon (i.e., 0.41 wt.%) while has comparable performance (discharge capacity of 80mAh/g at 2C) compared to traditionally synthesized carbon-coated LiFePO4 with higher carbon loadings (ca. 2.64 wt.%). This will enable us to produce batteries with higher active material loading and therefore, significantly larger energy densities.

The Production of 3D Tumor Spheroids for Cancer Drug Discovery

PubMed Central

Sant, Shilpa; Johnston, Paul A.

2017-01-01

New cancer drug approval rates are ≤ 5% despite significant investments in cancer research, drug discovery and development. One strategy to improve the rate of success of new cancer drugs transitioning into the clinic would be to more closely align the cellular models used in the early lead discovery with pre-clinical animal models and patient tumors. For solid tumors, this would mandate the development and implementation of three dimensional (3D) in vitro tumor models that more accurately recapitulate human solid tumor architecture and biology. Recent advances in tissue engineering and regenerative medicine have provided new techniques for 3D spheroid generation and a variety of in vitro 3D cancer models are being explored for cancer drug discovery. Although homogeneous assay methods and high content imaging approaches to assess tumor spheroid morphology, growth and viability have been developed, the implementation of 3D models in HTS remains challenging due to reasons that we discuss in this review. Perhaps the biggest obstacle to achieve acceptable HTS assay performance metrics occurs in 3D tumor models that produce spheroids with highly variable morphologies and/or sizes. We highlight two methods that produce uniform size-controlled 3D multicellular tumor spheroids that are compatible with cancer drug research and HTS; tumor spheroids formed in ultra-low attachment microplates, or in polyethylene glycol dimethacrylate hydrogel microwell arrays. PMID:28647083

Graphene/graphite paste electrode incorporated with molecularly imprinted polymer nanoparticles as a novel sensor for differential pulse voltammetry determination of fluoxetine.

PubMed

Alizadeh, Taher; Azizi, Sorour

2016-07-15

Molecularly imprinted polymer (MIP) nanoparticles including highly selective recognition sites for fluoxetine were synthesized, utilizing precipitation polymerization. Methacrylic acid and vinyl benzene were used as functional monomers. Ethylene glycol dimethacrylate was used as cross-linker agent. The obtained polymeric nanoparticles were incorporated with carbon paste electrode (CPE) in order to construct a fluoxetine selective sensor. The response of the MIP-CP electrode to fluoxetine was remarkably higher than the electrode, modified with the non-imprinted polymer, indicating the excellent efficiency of the MIP sites for target molecule recognition. It was found that the addition of a little amount of graphene, synthesized via modified hummer's method, to the MIP-CP resulted in considerable enhancement in the sensitivity of the electrode to fluoxetine. Also, the style of electrode components mixing, before carbon paste preparation, was demonstrated to be influential factor in the electrode response. Some parameters, affecting sensor response, were optimized and then a calibration curve was plotted. A dynamic linear range of 6×10(-9)-1.0×10(-7)molL(-1) was obtained. The detection limit of the sensor was calculated equal to 2.8×10(-9)molL(-1) (3Sb/m). This sensor was used successfully for fluoxetine determination in the spiked plasma samples as well as fluoxetine capsules. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface plasmon resonance sensor for femtomolar detection of testosterone with water-compatible macroporous molecularly imprinted film.

PubMed

Zhang, Qingwen; Jing, Lijing; Zhang, Jinling; Ren, Yamin; Wang, Yang; Wang, Yi; Wei, Tianxin; Liedberg, Bo

2014-10-15

A novel water-compatible macroporous molecularly imprinted film (MIF) has been developed for rapid, sensitive, and label-free detection of small molecule testosterone in urine. The MIF was synthesized by photo copolymerization of monomers (methacrylic acid [MAA] and 2-hydroxyethyl methacrylate [HEMA]), cross-linker (ethylene glycol dimethacrylate, EGDMA), and polystyrene nanoparticles (PS NPs) in combination with template testosterone molecules. The PS NPs and template molecules were subsequently removed to form an MIF with macroporous structures and the specific recognition sites of testosterone. Incubation of artificial urine and human urine on the MIF and the non-imprinted film (NIF), respectively, indicated undetectable nonspecific adsorption. Accordingly, the MIF was applied on a surface plasmon resonance (SPR) sensor for the detection of testosterone in phosphate-buffered saline (PBS) and artificial urine with a limit of detection (LOD) down to 10(-15)g/ml. To the best of our knowledge, the LOD is considered as one of the lowest among the SPR sensors for the detection of small molecules. The control experiments performed with analogue molecules such as progesterone and estradiol demonstrated the good selectivity of this MIF for sensing testosterone. Furthermore, this MIF-based SPR sensor shows high stability and reproducibility over 8months of storage at room temperature, which is more robust than protein-based biosensors. Copyright © 2014 Elsevier Inc. All rights reserved.

Ion imprinted polymeric nanoparticles for selective separation and sensitive determination of zinc ions in different matrices

NASA Astrophysics Data System (ADS)

Shamsipur, Mojtaba; Rajabi, Hamid Reza; Pourmortazavi, Seied Mahdi; Roushani, Mahmoud

2014-01-01

Preparation of Zn2+ ion-imprinted polymer (Zn-IIP) nanoparticles is presented in this report. The Zn-IIP nanoparticles are prepared by dissolving stoichiometric amounts of zinc nitrate and selected chelating ligand, 3,5,7,20,40-pentahydroxyflavone, in 15 mL ethanol-acetonitrile (2:1; v/v) mixture as a porogen solvent in the presence of ethylene glycol-dimethacrylate (EGDMA) as cross-linking, methacrylic acid (MAA) as functional monomer, and 2,2-azobisisobutyronitrile (AIBN) as initiator. After polymerization, Cavities in the polymer particles corresponding to the Zn2+ ions were created by leaching the polymer in HCl aqueous solution. The synthesized IIPs were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal analysis techniques. Also, the pH range for rebinding of Zn2+ ion on the IIP and equilibrium binding time were optimized, using flame atomic absorption spectrometry. In selectivity study, it was found that imprinting results increased affinity of the material toward Zn2+ ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIPs were repeatedly used and regenerated for six times without any significant decrease in polymer binding affinities. Finally, the prepared sorbent was successfully applied to the selective recognition and determination of zinc ion in different real samples.

(Meth)Acrylate Occupational Contact Dermatitis in Nail Salon Workers: A Case Series.

PubMed

DeKoven, Samuel; DeKoven, Joel; Holness, D Linn

Recently, many cases of acrylate-associated allergic contact dermatitis have appeared among nail salon workers. Common acrylate-containing products in nail salons include traditional nail polish, ultraviolet-cured shellac nail polish, ultraviolet-cured gel nails, and press-on acrylic nails. Nail salon technicians seen in the occupational medicine clinic in 2015 and 2016 were identified, and their patch test results and clinical features were summarized. Patch testing was done with the Chemotechnique (Meth)Acrylate nail series, and either the North American Standard series or the North American Contact Dermatitis Group screening series. Six patients were identified, all women, ages 38 to 58. Common presentations included erythematous dermatitis of the dorsa of the hands, palms, and forearms and fissures on the fingertips. Less common sites of eruptions included the periorbital region, cheeks, posterior ears, neck, sacral area, lateral thighs, and dorsa of the feet. All patients reacted to hydroxyethyl methacrylate, and 5 patients reacted to ethyl acrylate. Each patient also reacted to (meth)acrylates that are not found on either standard series, including ethyleneglycol dimethacrylate, 2-hydroxypropyl methacrylate, and 2-hydroxyethyl acrylate. The authors report 6 cases of allergic contact dermatitis to acrylates in nail technicians seen over the past year, representing a new trend in their clinic. These cases are reflective of a growing trend of nail technicians with allergic contact dermatitis associated with occupational (meth)acrylate exposure. Efforts to improve prevention are needed.

Determination of Carvedilol Enantiomers in Pharmaceutical Dosages by SBSE-HPLC Based on Diastereomer Formation.

PubMed

Taraji, Maryam; Talebpour, Zahra; Adib, Nuoshin; Karimi, Shima; Haghighi, Farideh; Aboul-Enein, Hassan Y

2015-09-01

A sensitive, selective and simple method for the simultaneous determination of carvedilol enantiomers in aqueous solution has been developed using stir bar sorptive extraction (SBSE) followed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. This method is based on the reaction of carvedilol enantiomers with (-)-menthyl chloroformate (MCF) after extraction by the SBSE method to produce diastereomeric derivatives. The separation was achieved by use of a C18 analytical column and the influence of mobile phase composition on the enantioseparation of carvedilol was studied. The applicability of two sorptive phases, poly(methyl methacrylate/ethyleneglycol dimethacrylate) (PA-EG) and polydimethylsiloxane, were tested for extraction of carvedilol enantiomers from aqueous samples. The obtained results showed excellent linear dynamic ranges and precisions for each of them. The least limit of detection for (S)- and (R)-carvedilol obtained 8 and 11 µg L(-1), respectively, using the PA-EG sorptive phase. Inter- and intra-mean recoveries were also satisfactory, ranging from 98 to 103%, with coefficient of variation in the range of 1-5% at three fortified levels using a PA-EG coated stir bar. The proposed SBSE (PA-EG)-MCF derivatization-HPLC-UV method was successfully applied to enantioselective analysis of carvedilol in water and pharmaceutical dosages, confirming the application of this method. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Preparation and evaluation of dual-enzyme microreactor with co-immobilized trypsin and chymotrypsin.

PubMed

Meller, Kinga; Pomastowski, Paweł; Grzywiński, Damian; Szumski, Michał; Buszewski, Bogusław

2016-04-01

The preparation of capillary microfluidic reactor with co-immobilized trypsin and chymotrypsin with the use of a low-cost commercially available enzymatic reagent (containing these proteases) as well as the evaluation of its usefulness in proteomic research were presented. The monolithic copolymer synthesized from glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) was used as a support. Firstly, the polymerization conditions were optimized and the monolithic bed was synthesized in the fused silica capillary modified with 3-(trimethoxysilyl)propyl methacrylate (γ-MAPS). The polymer containing epoxy groups was then modified with 1,6-diaminohexane, followed by the attachment of glutaraldehyde and immobilization of enzymes. The efficiency of the prepared monolithic Immobilized Enzyme Microreactor (μ-IMER) with regard to trypsin activity was evaluated using the low-molecular mass compound (Nα-benzoyl-l-arginine ethyl ester, BAEE). The activities of both enzymes were investigated using a macromolecular protein (human transferrin, Tf) as a substrate. In the case of BAEE, the reaction product was separated from the substrate using the capillary liquid chromatography and the efficiency of the reaction was determined by the peak area of the substrate. The hydrolysis products of transferrin were analyzed with MALDI-TOF which allows for the verification of the prepared enzymatic system applicability in the field of proteomic research. Copyright © 2016 Elsevier B.V. All rights reserved.

Imprinted polymer-carbon consolidated composite fiber sensor for substrate-selective electrochemical sensing of folic acid.

PubMed

Prasad, Bhim Bali; Madhuri, Rashmi; Tiwari, Mahavir Prasad; Sharma, Piyush Sindhu

2010-05-15

Molecularly imprinted polymers (MIPs) are often electrically insulating materials. Due to the presence of diffusion barrier(s) in between such MIP coating and electrode surface and the absence of a direct path for the conduction of electrons from the binding sites to the electrode, the development of electrochemical sensor is significantly restricted. The direct use of MIPs those possess intrinsic electron-transport properties, is highly limited. These problems are resolved by the design of an original, substrate-selective MIP-fiber sensor that combines conventional insulating MIP and conducting carbon powder in consolidated phase. A layer of conducting carbon particles, arranged orderly as 'carbon strip', is inducted in the polymer for direct electronic conduction. MIP-carbon composite (monolithic fiber) in this work is prepared via in situ free radical polymerization of a new monomer (2,4,6-trisacrylamido-1,3,5-triazine, TAT) and subsequent cross-linkage with ethylene glycol dimethacrylate, in the presence of carbon powder and template (folic acid), at 55 degrees C in a glass capillary. The detection of folic acid with the MIP-fiber sensor was found to be specific and quantitative (detection limit 0.20 ng mL(-1), RSD=1.3%, S/N=3), in aqueous, blood serum and pharmaceutical samples, without any problem of non-specific false-positive contribution and cross-reactivity. 2010 Elsevier B.V. All rights reserved.

Highly selective coextraction of rhodamine B and dibenzyl phthalate based on high-density dual-template imprinted shells on silica microparticles.

PubMed

Long, Zerong; Xu, Weiwei; Peng, Yumei; Lu, Yi; Luo, Qian; Qiu, Hongdeng

2017-01-01

A simple one-pot approach based on molecularly imprinted polymer shells dispersed on the surface of silica for simultaneous determination of rhodamine B and dibenzyl phthalate (DBzP) has been developed. Highly dense molecularly imprinted polymer shells were formed in the mixture of acetonitrile and toluene by the copolymerization of methacrylic acid and ethylene glycol dimethacrylate, as well as two templates, rhodamine B and dibenzyl phthalate, directed by the vinyl end groups functional monolayer at surface silica microspheres after 3-methacryloxypropyl trimethoxysilane modification. The obtained imprinted polymer shells showed large average pore diameter (102.5 nm) and about 100 nm shell thickness. The imprinted particles also showed high imprinting factor (α RhB = 3.52 and α DBzP = 3.94), rapid binding kinetics, and excellent selective affinity capacity for rhodamine B and dibenzyl phthalate containing another three competitors in mixed solution. Moreover, the imprinted particles coupled with ultra high performance liquid chromatography was successfully applied to simultaneous analysis of rhodamine B and dibenzyl phthalate in two spiked beverage samples with average recoveries in the range of 88.0-93.0% for rhodamine B and 84.0-92.0% for dibenzyl phthalate with the relative standard deviation lower than 5.1%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In Situ Experiments To Reveal the Role of Surface Feature Sidewalls in the Cassie–Wenzel Transition

PubMed Central

2014-01-01

Waterproof and self-cleaning surfaces continue to attract much attention as they can be instrumental in various different technologies. Such surfaces are typically rough, allowing liquids to contact only the outermost tops of their asperities, with air being entrapped underneath. The formed solid–liquid–air interface is metastable and, hence, can be forced into a completely wetted solid surface. A detailed understanding of the wetting barrier and the dynamics of this transition is critically important for the practical use of the related surfaces. Toward this aim, wetting transitions were studied in situ at a set of patterned perfluoropolyether dimethacrylate (PFPEdma) polymer surfaces exhibiting surface features with different types of sidewall profiles. PFPEdma is intrinsically hydrophobic and exhibits a refractive index very similar to water. Upon immersion of the patterned surfaces into water, incident light was differently scattered at the solid–liquid–air and solid–liquid interface, which allows for distinguishing between both wetting states by dark-field microscopy. The wetting transition observed with this methodology was found to be determined by the sidewall profiles of the patterned structures. Partial recovery of the wetting was demonstrated to be induced by abrupt and continuous pressure reductions. A theoretical model based on Laplace’s law was developed and applied, allowing for the analytical calculation of the transition barrier and the potential to revert the wetting upon pressure reduction. PMID:25496232

Acrylate and methacrylate contact allergy and allergic contact disease: a 13-year review.

PubMed

Spencer, Ashley; Gazzani, Paul; Thompson, Donna A

2016-09-01

(Meth)acrylates are important causes of contact allergy and allergic contact disease, such as dermatitis and stomatitis, with new and emerging sources resulting in changing clinical presentations. To identify the (meth)acrylates that most commonly cause allergic contact disease, highlight their usefulness for screening, and examine their relationship with occupational and clinical data. A retrospective review of results from patch tests performed between July 2002 and September 2015, in one tertiary Cutaneous Allergy Unit, was performed A series of 28 (meth)acrylates was applied to 475 patients. Results were positive in 52 cases, with occupational sources being identified in 24. Industrial exposures and acrylic nails were responsible for 13 and 10 cases, respectively, with wound dressings being implicated in 7. We found that four individual (meth)acrylates (2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, bisphenol A glycerolate dimethacrylate, and ethyl acrylate), if used as a screening tool, could have identified 47 (90.4%) of our positive cases. Our 13-year experience indicates a changing landscape of (meth)acrylate contact allergy and allergic contact disease, with an observed shift in exposures away from manufacturing and towards acrylic nail sources. Wound dressings are highlighted as emerging sources of sensitization. Larger studies are required to establish the sensitivity and specificity of the four (meth)acrylates proposed for potential screening. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Allergic contact dermatitis caused by (meth)acrylates in nail cosmetic products in users and nail technicians - a 5-year study.

PubMed

Raposo, Inês; Lobo, Inês; Amaro, Cristina; Lobo, Maria de Lurdes; Melo, Helena; Parente, Joana; Pereira, Teresa; Rocha, Joana; Cunha, Ana P; Baptista, Armando; Serrano, Pedro; Correia, Teresa; Travassos, Ana R; Dias, Margarida; Pereira, Fátima; Gonçalo, Margarida

2017-12-01

The increasing use of long-lasting nail aesthetic products has led to a growing number of cases of allergic contact dermatitis (ACD) caused by (meth)acrylates in recent years. To provide information on ACD caused by (meth)acrylates related to nail cosmetic products. We retrospectively reviewed files of patients with ACD caused by (meth)acrylates related to nail cosmetic products, who were patch tested between January 2011 and December 2015 in 13 departments of dermatology in Portugal. Two-hundred and thirty cases of ACD caused by (meth)acrylates (55 technicians, 56 consumers, and 119 with mixed exposure) had been documented, mostly as chronic hand eczema (93%). The most common sensitizers were: 2-hydroxyethyl methacrylate (HEMA), which was positive in 90% of the tested patients, 2-hydroxypropyl methacrylate (HPMA), which was positive in 64.1%, and ethyleneglycol dimethacrylate, which was positive in 54.5%. HEMA and HPMA were the most frequent positive allergens. HEMA, which identified 90% of cases, can be considered to be a good screening allergen. The high number of cases of ACD caused by (meth)acrylates in nail cosmetic products certainly warrants better preventive measures at the occupational level, and specific regulation in the field of consumer safety. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biomimetic ELISA detection of malachite green based on magnetic molecularly imprinted polymers.

PubMed

Li, Lu; Lin, Zheng-Zhong; Peng, Ai-Hong; Zhong, Hui-Ping; Chen, Xiao-Mei; Huang, Zhi-Yong

2016-11-01

A direct competitive enzyme-linked immunosorbent assay (ELISA) method was used for the detection of malachite green (MG) with a high sensitivity and selectivity using magnetic molecularly imprinted polymers (MMIPs) as a bionic antibody. MMIPs were prepared through emulsion polymerization using Fe 3 O 4 nanoparticles as magnetic nuclei, MG as a template, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent and span-80/tween-80 as mixed emulsifiers. The MMIPs were characterized by scanning electron micrographs (SEM), thermal-gravimetric analyzer (TGA), Fourier transform infrared spectrometer (FT-IR) and vibrating sample magnetometer (VSM), respectively. A high magnetic saturation value of 54.1emug -1 was obtained, resulting in rapid magnetic separation of MMIPs with an external magnet. The IC 50 of the established ELISA method was 20.1μgL -1 and the detection limit (based on IC 85 ) was 0.1μgL -1 . The MMIPs exhibited high selective binding capacity for MG with cross-reactivities less than 3.9% for MG structural analogues. The MG spiking recoveries were 85.0%-106% with the relative standard deviations less than 4.7%. The results showed that the biomimetic ELISA method by using MMIPs as bionic antibody could be used to detect MG rapidly in fish samples with a high sensitivity and accuracy. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of ibuprofen, naproxen and diclofenac in aqueous samples using a multi-template molecularly imprinted polymer as selective adsorbent for solid-phase extraction.

PubMed

Madikizela, Lawrence Mzukisi; Chimuka, Luke

2016-09-05

This study describes the application of multi-template molecularly imprinted polymer (MIP) as selective sorbent in the solid-phase extraction (SPE) of naproxen, ibuprofen and diclofenac from wastewater and river water. MIP was synthesized at 70°C by employing naproxen, ibuprofen and diclofenac as multi-templates, ethylene glycol dimethacrylate, 2-vinyl pyridine and toluene as cross-linker, functional monomer and porogen, respectively. Wastewater and river water samples (pH 2.5) were percolated through SPE cartridge packed with 50mg of the MIP. The cartridge was washed with 2mL of methanol-water 10:90% (v:v) prior to elution with 2mL of acetic acid-acetonitrile 20:80% (v:v). Quantification of eluted compounds was performed with high performance liquid chromatography equipped with photo diode array detection. The detection limits were 0.15, 1.00 and 0.63μgL(-1) for naproxen, ibuprofen and diclofenac, respectively. Recoveries for naproxen, ibuprofen and diclofenac in deionized water spiked at 5 and 50μgL(-1) were greater than 80%. Ibuprofen was the most frequently detected compound with maximum concentrations of 221, 67.9 and 11.4μgL(-1) in wastewater influent, effluent and river water, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Polymer monolithic capillary microextraction on-line coupled with inductively coupled plasma-mass spectrometry for the determination of trace Au and Pd in biological samples

NASA Astrophysics Data System (ADS)

Liu, Xiaolan; He, Man; Chen, Beibei; Hu, Bin

2014-11-01

A novel method based on on-line polymer monolithic capillary microextraction (CME)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace Au and Pd in biological samples. For this purpose, poly(glycidyl methacrylate-ethylene dimethacrylate) monolith was prepared and functionalized with mercapto groups. The prepared monolith exhibited good selectivity to Au and Pd, and good resistance to strong acid with a long life span. Factors affecting the extraction efficiency of CME, such as sample acidity, sample flow rate, eluent conditions and coexisting ion interference were investigated in detail. Under the optimal conditions, the limits of detection (LODs, 3σ) were 5.9 ng L- 1 for Au and 8.3 ng L- 1 for Pd, and the relative standard deviations (RSDs, c = 50 ng L-1, n = 7) were 6.5% for Au and 1.1% for Pd, respectively. The developed method was successfully applied to the determination of Au and Pd in human urine and serum samples with the recovery in the range of 84-118% for spiked samples. The developed on-line polymer monolithic CME-ICP-MS method has the advantages of rapidity, simplicity, low sample/reagent consumption, high sensitivity and is suitable for the determination of trace Au and Pd in biological samples with limited amount available and complex matrix.

Sensitive determination of estrogens in environmental waters treated with polymeric ionic liquid-based stir cake sorptive extraction and liquid chromatographic analysis.

PubMed

Chen, Lei; Mei, Meng; Huang, Xiaojia; Yuan, Dongxing

2016-05-15

A simple, sensitive and environmentally friendly method using polymeric ionic liquid-based stir cake sorptive extraction followed by high performance liquid chromatography with diode array detection (HPLC/DAD) has been developed for efficient quantification of six selected estrogens in environmental waters. To extract trace estrogens effectively, a poly (1-ally-3-vinylimidazolium chloride-co-ethylene dimethacrylate) monolithic cake was prepared and used as the sorbent of stir cake sorptive extraction (SCSE). The effects of preparation conditions of sorbent and extraction parameters of SCSE for estrogens were investigated and optimized. Under optimal conditions, the developed method showed satisfactory analytical performance for targeted analytes. Low limits of detection (S/N=3) and quantification limits (S/N=10) were achieved within the range of 0.024-0.057 µg/L and 0.08-0.19 µg/L, respectively. Good linearity of method was obtained for analytes with the correlation coefficients (R(2)) above 0.99. At the same time, satisfactory method repeatability and reproducibility was achieved in terms of intra- and inter-day precisions, respectively. Finally, the established SCSE-HPLC/DAD method was successfully applied for the determination of estrogens in different environmental water samples. Recoveries obtained for the determination of estrogens in spiked samples ranged from 71.2% to 108%, with RSDs below 10% in all cases. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of 2,4-dichlorophenoxyacetic acid imprinted organic-inorganic hybrid monolithic column and application to selective solid-phase microextraction.

PubMed

Liu, Xiaofang; Zhu, Quanfei; Chen, Huaixia; Zhou, Liuzi; Dang, Xueping; Huang, Jianlin

2014-03-01

An organic-inorganic hybrid molecular imprinting monolith (HMIM) has been prepared, characterized and applied for the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) in rice with high-performance liquid chromatography-photodiodes array detector (HPLC-PAD). By optimizing the polymerization conditions, such as the volume ratio of the inorganic alcoholysate and organic part, the 2,4-D-HMIM was synthesized in a micro pipette tip using acrylamide as the functional monomer, ethylene dimethacrylate as the cross-linker and methanol as the porogenic solvent. The morphology of the monolith was studied by scanning electronmicroscopy and Fourier transform infrared spectra. The imprinted factor of the monolith for 2,4-D reached 3.29. A simple, rapid and sensitive method for the determination of 2,4-D in rice using the HMIM microextraction combined with high-performance liquid chromatography-photodiodes array detector was developed. Some parameters affecting the sample pretreatment were investigated, including the type and volume of eluent, the flow rate and volume of sample solution. The assay exhibited a linear dynamic range of 167-4167μg/kg with the correlation coefficient above 0.9972. The detection limit (at S/N=3) was 50μg/kg. The proposed method was successfully applied for the selective determination of 2,4-D in rice. Copyright © 2014 Elsevier B.V. All rights reserved.

Integrated photografted molecularly imprinted polymers with a cellulose acetate membrane for the extraction of melamine from dry milk before HPLC analysis.

PubMed

Akbari-Adergani, Behrouz; Sadeghian, Gholam-Hossein; Alimohammadi, Alireza; Esfandiari, Zahra

2017-03-01

In this study, a new separation technique based on membrane extraction is described for the determination of melamine in dry milk. The water-compatible cellulose acetate membrane, which is photografted by melamine imprinted nanospheres, was prepared by placing the membrane into the polymerization solution containing methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as cross-linker, acetonitrile as porogen, and melamine as the template molecule. The characterization of the polymeric membrane was performed by Fourier transmission infrared spectroscopy and scanning electron microscopy. This integrated composite membrane was used as a solid-phase extraction medium for the extraction of melamine from dry milk samples. Various parameters affecting the extraction efficiency of the membrane were evaluated. The results showed higher binding capacity for melamine imprinted membranes in comparison with the nonimprinted membranes. High-performance liquid chromatography analysis showed that the extraction of melamine from dry milk by the photografted cellulose acetate membrane had a linear calibration curve in the range of 0.02-11.80 μg/mL with an excellent precision of 2.73%. The limit of detection and quantification of melamine was 0.007 and 0.020 μg/mL, respectively. The recoveries of melamine were in the range of 88.7-94.8%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitative analysis of aqueous phase composition of model dentin adhesives experiencing phase separation

PubMed Central

Ye, Qiang; Park, Jonggu; Parthasarathy, Ranganathan; Pamatmat, Francis; Misra, Anil; Laurence, Jennifer S.; Marangos, Orestes; Spencer, Paulette

2013-01-01

There have been reports of the sensitivity of our current dentin adhesives to excess moisture, for example, water-blisters in adhesives placed on over-wet surfaces, and phase separation with concomitant limited infiltration of the critical dimethacrylate component into the demineralized dentin matrix. To determine quantitatively the hydrophobic/hydrophilic components in the aqueous phase when exposed to over-wet environments, model adhesives were mixed with 16, 33, and 50 wt % water to yield well-separated phases. Based upon high-performance liquid chromatography coupled with photodiode array detection, it was found that the amounts of hydrophobic BisGMA and hydrophobic initiators are less than 0.1 wt % in the aqueous phase. The amount of these compounds decreased with an increase in the initial water content. The major components of the aqueous phase were hydroxyethyl methacrylate (HEMA) and water, and the HEMA content ranged from 18.3 to 14.7 wt %. Different BisGMA homologues and the relative content of these homologues in the aqueous phase have been identified; however, the amount of crosslinkable BisGMA was minimal and, thus, could not help in the formation of a crosslinked polymer network in the aqueous phase. Without the protection afforded by a strong crosslinked network, the poorly photoreactive compounds of this aqueous phase could be leached easily. These results suggest that adhesive formulations should be designed to include hydrophilic multimethacrylate monomers and water compatible initiators. PMID:22331596

The effect of incorporating different concentrations of chlorhexidine digluconate on the degree of conversion of an experimental adhesive resin.

PubMed

Moharam, Lamiaa-Mahmoud; Salem, Haidy-Nabil; Elgamily, Hanaa-Mahmoud

2018-04-01

The aim of this study was to evaluate the effect of chlorhexidine digluconate incorporation on the degree of conversion of an experimental adhesive resin. The experimental resin was prepared from 70 wt% bisphenol A glycerolate dimethacrylate, 30 wt% hydroxyethyl methacrylate, silanized SiO2 nanofillers, 0.5% of camphorquinone and ethyl 4-dimethylaminebenzoate (binary photo-initiator system). Five chlorhexidine digluconate concentrations (0, 0.5, 1, 2 and 4 wt%) were then incorporated into the experimental resin. Thirty Potassium Bromide pellets were prepared then divided into six groups (n=5/group), repre¬senting the tested adhesive resins (Single Bond 2, 0, 0.5, 1, 2 and 4 wt% chlohexidine-incorporated experimental adhesive resins), that were applied to the pellets without light-curing (uncured specimens). Another 30 pellets were prepared and treated with the previous materials then light-cured using LED light-curing device (cured specimens). Degree of conversion of the uncured and the cured specimens were evaluated using FTIR analysis. Adper Single Bond 2 showed the highest degree of conversion mean values followed by 0.5 wt% chlorhexidine concentration then 2 wt% followed by 4 wt% then 1 wt% concentrations, while 0 wt% concentration showed the lowest mean values. Chlorhexidine digluconate had slight significant influence on the efficiency of polymerization of the experimental adhesive resin. Key words: Chlorhexidine digluconate, different concentrations, degree of conversion, experimental adhesive resin.

Preparation of magnetic molecularly imprinted polymers by atom transfer radical polymerization for the rapid extraction of avermectin from fish samples.

PubMed

You, Xiaoxiao; Gao, Lei; Qin, Dongli; Chen, Ligang

2017-01-01

A novel and highly efficient approach to obtain magnetic molecularly imprinted polymers is described to detect avermectin in fish samples. The magnetic molecularly imprinted polymers were synthesized by surface imprinting polymerization using magnetic multiwalled carbon nanotubes as the support materials, atom transfer radical polymerization as the polymerization method, avermectin as template, acrylamide as functional monomer, and ethylene glycol dimethacrylate as crosslinker. The characteristics of the magnetic molecularly imprinted polymers were assessed by using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometry, X-ray diffraction, and thermogravimetric analysis. The binding characteristics of magnetic molecularly imprinted polymers were researched through isothermal adsorption experiment, kinetics adsorption experiment, and the selectivity experiment. Coupled with ultra high performance liquid chromatography and tandem mass spectrometry, the extraction conditions of the magnetic molecularly imprinted polymers as adsorbents for avermectin were investigated in detail. The recovery of avermectin was 84.2-97.0%, and the limit of detection was 0.075 μg/kg. Relative standard deviations of intra- and inter-day precisions were in the range of 1.7-2.9% and 3.4-5.6%, respectively. The results demonstrated that the extraction method not only has high selectivity and accuracy, but also is convenient for the determination of avermectin in fish samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DEVELOPMENT OF AN AFFINITY SILICA MONOLITH CONTAINING HUMAN SERUM ALBUMIN FOR CHIRAL SEPARATIONS

PubMed Central

Mallik, Rangan; Hage, David S.

2008-01-01

An affinity monolith based on silica and containing immobilized human serum albumin (HSA) was developed and evaluated in terms of its binding, efficiency and selectivity in chiral separations. The results were compared with data obtained for the same protein when used as a chiral stationary phase with HPLC-grade silica particles or a monolith based on a copolymer of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA). The surface coverage of HSA in the silica monolith was similar to values obtained with silica particles and a GMA/EDMA monolith. However, the higher surface area of the silica monolith gave a material that contained 1.3- to 2.2-times more immobilized HSA per unit volume when compared to silica particles or a GMA/EDMA monolith. The retention, efficiency and resolving power of the HSA silica monolith were evaluated using two chiral analytes: D/L-tryptophan and R/S-warfarin. The separation of R- and S-ibuprofen was also considered. The HSA silica monolith gave higher retention and higher or comparable resolution and efficiency when compared with HSA columns that contained silica particles or a GMA/EDMA monolith. The silica monolith also gave lower back pressures and separation impedances than these other materials. It was concluded that silica monoliths can be valuable alternatives to silica particles or GMA/EDMA monoliths when used with immobilized HSA as a chiral stationary phase. PMID:17475436

Molecular imprinting solid phase extraction for selective detection of methidathion in olive oil.

PubMed

Bakas, Idriss; Oujji, Najwa Ben; Moczko, Ewa; Istamboulie, Georges; Piletsky, Sergey; Piletska, Elena; Ait-Ichou, Ihya; Ait-Addi, Elhabib; Noguer, Thierry; Rouillon, Régis

2012-07-13

A specific adsorbent for extraction of methidathion from olive oil was developed. The design of the molecularly imprinted polymer (MIP) was based on the results of the computational screening of the library of polymerisable functional monomers. MIP was prepared by thermal polymerisation using N,N'-methylene bisacrylamide (MBAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The polymers based on the itaconic acid (IA), methacrylic acid (MAA) and 2-(trifluoromethyl)acryl acid (TFMAA) functional monomers and one control polymer which was made without functional monomers with cross-linker EGDMA were also synthesised and tested. The performance of each polymer was compared using corresponding imprinting factor. As it was predicted by molecular modelling the best results were obtained for the MIP prepared with MBAA. The obtained MIP was optimised in solid-phase extraction coupled with high performance liquid chromatography (MISPE-HPLC-UV) and tested for the rapid screening of methidathion in olive oil. The proposed method allowed the efficient extraction of methidathion for concentrations ranging from 0.1 to 9 mg L(-1) (r(2)=0.996). The limits of detection (LOD) and quantification (LOQ) in olive oil were 0.02 mg L(-1) and 0.1 mg L(-1), respectively. MIPs extraction was much more effective than traditional C18 reverse-phase solid phase extraction. Copyright © 2012 Elsevier B.V. All rights reserved.

Molecularly imprinted polymers coated on multi-walled carbon nanotubes through a simple indirect method for the determination of 2,4-dichlorophenoxyacetic acid in environmental water

NASA Astrophysics Data System (ADS)

Yang, Weijie; Jiao, Feipeng; Zhou, Lei; Chen, Xiaoqing; Jiang, Xinyu

2013-11-01

A new and facile method was presented to graft molecularly imprinted polymers (MIPs) on carbon nanotubes (CNTs) for 2,4-dichlorophenoxyacetic acid (2,4-D) analysis. In brief, CNTs were firstly coated with a layer of vinyl group modified silica, followed by a common precipitation polymerization with 2,4-D as the template, ethylene glycol dimethacrylate (EGDMA) as the crosslinker and 2,2-azobisisobutyronitrile (AIBN) as the initiator. The imprinted effects obtained by using different monomers were investigated, and the results showed that acrylamide (AM) and styrene as mixed monomers was the best choice. This functionalized material was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetry (TG), which demonstrated a successful polymerization reaction on CNTs with MIPs grafting ratio of about 80%. The results of static adsorption experiments indicated the imprinted material possessed fast kinetics and good selectivity for 2,4-D molecules. A corresponding analytical method was developed and demonstrated to be applicable for the determination of 2,4-D in environmental water. The recoveries were in the range from 74.6% to 81.2% with relative standard deviation below 7.0%. To be emphasized, the method for MIPs coating proposed herein also provides a significant reference for other radical polymerization reactions based on CNTs.

Monolithic metal-organic framework MIL-53(Al)-polymethacrylate composite column for the reversed-phase capillary liquid chromatography separation of small aromatics.

PubMed

Yusuf, Kareem; Badjah-Hadj-Ahmed, Ahmed Yacine; Aqel, Ahmad; ALOthman, Zeid Abdullah

2016-03-01

A monolithic capillary column containing a composite of metal-organic framework MIL-53(Al) incorporated into hexyl methacrylate-co-ethylene dimethacrylate was prepared to enhance the separation of mixtures of small aromatic compounds by using capillary liquid chromatography. The addition of 10 mg/mL MIL-53(Al) microparticles increased the micropore content in the monolithic matrix and increased the Brunauer-Emmett-Teller surface area from 26.92 to 85.12 m(2) /g. The presence of 1,4-benzenedicarboxylate moieties within the structure of MIL-53(Al) as an organic linker greatly influenced the separation of aromatic mixtures through π-π interactions. High-resolution separation was obtained for a series of alkylbenzenes (with resolution factors in the range 0.96-1.75) in less than 8 min, with 14 710 plates/m efficiency for propylbenzene, using a binary polar mobile phase of water/acetonitrile in isocratic mode. A reversed-phase separation mechanism was indicated by the increased retention factor and resolution as the water percentage in the mobile phase increased. A stability study on the composite column showed excellent mechanical stability under various conditions. The higher resolution and faster separation observed at increased temperature indicated an exothermic separation, whereas the negative values for the free energy change of transfer indicated a spontaneous process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Incorporation of metal-organic framework HKUST-1 into porous polymer monolithic capillary columns to enhance the chromatographic separation of small molecules.

PubMed

Yang, Shengchao; Ye, Fanggui; Lv, Qinghui; Zhang, Cong; Shen, Shufen; Zhao, Shulin

2014-09-19

Metal-organic framework (MOF) HKUST-1 nanoparticles have been incorporated into poly(glycidyl methacrylate-co-ethylene dimethacrylate) (HKUST-1-poly(GMA-co-EDMA)) monoliths to afford stationary phases with enhanced chromatographic performance of small molecules in the reversed phase capillary liquid chromatography. The effect of HKUST-1 nanoparticles in the polymerization mixture on the performance of the monolithic column was explored in detail. While the bare poly(GMA-co-EDMA) monolith exhibited poor resolution (Rs<1.0) and low efficiency (800-16,300plates/m), addition of a small amount of HKUST-1 nanoparticles to the polymerization mixture provide high increased resolution (Rs≥1.3) and high efficiency ranged from 16,300 to 44,300plates/m. Chromatographic performance of HKUST-1-poly(GMA-co-EDMA) monolith was demonstrated by separation of various analytes including polycyclic aromatic hydrocarbons, ethylbenzene and styrene, phenols and aromatic acids using a binary polar mobile phase (CH3CN/H2O). The HKUST-1-poly(GMA-co-EDMA) monolith displayed enhanced hydrophobic and π-π interaction characteristics in the reversed phase separation of test analytes compared to the bare poly(GMA-co-EDMA) monolith. The experiment results showed that HKUST-1-poly(GMA-co-EDMA) monoliths are an alternative to enhance the chromatographic separation of small molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

MIPs-graphene nanoplatelets-MWCNTs modified glassy carbon electrode for the determination of cardiac troponin I.

PubMed

Ma, Ya; Shen, Xiao-Lei; Wang, Hai-Shui; Tao, Jia; Huang, Jian-Zhi; Zeng, Qiang; Wang, Li-Shi

2017-03-01

An electrochemical sensor with high selectivity in addition to sensitivity was developed for the determination of cardiac troponin I (cTnI), based on the modification of cTnI imprinted polymer film on a glassy carbon electrode (GCE). The sensor was fabricated by layer-by-layer assembled graphene nanoplatelets (GS), multiwalled carbon nanotubes (MWCNTs), chitosan (CS), glutaraldehyde (GA) composites, which can increase the electronic transfer rate and the active surface area to capture a larger number of antigenic proteins. MWCNTs/GS based imprinted polymers (MIPs/MWCNTs/GS) were synthesized by means of methacrylic acid (MAA) as the monomer, ethylene glycol dimethacrylate (EGDMA) as the cross linker α,α'-azobisisobutyronitrile (AIBN) as the initiator and cTnI as the template. In comparison with conventional methods, the proposed electrochemical sensor is highly sensitive for cTnI, providing a better linear response range from 0.005 to 60 ng cm -3 and a lower limit of detection (LOD) of 0.0008 ng cm -3 under optimal experimental conditions. In addition, the electrochemical sensor exhibited good specificity, acceptable reproducibility and stability. Moreover, satisfactory results were obtained in real human serum samples, indicating that the developed method has the potential to find application in clinical detection of cTnI as an alternative approach. Copyright © 2016 Elsevier Inc. All rights reserved.

Preparation and evaluation of molecularly imprinted polymers based on 9-ethyladenine for the recognition of nucleotide bases in capillary electrochromatography.

PubMed

Huang, Yi-Chen; Lin, Chun-Chi; Liu, Chuen-Ying

2004-02-01

A molecularly imprinted polymer (MIP) comprising 9-ethyladenine was polymerized in situ inside the capillary for the electrochromatographic separation of nucleotide bases. The capillary wall was first functionalized with 3-trimethoxysilylpropyl methacrylate (10% v/v) and 1,1-diphenyl-2-picrylhydrazyl (0.01% w/v) in toluene. Following this treatment, the capillary was filled with acetonitrile containing 9-ethyladenine, methacrylic acid, ethylene glycol dimethacrylate, and initiator. After polymerization, the MIP was shrunk into a film against the inner wall of the capillary with the syringe pump. The template was then removed with methanol under nitrogen flow. For evaluation the feasibility of the MIP column for the separation of nucleotide bases, some parameters including the pH, concentration of the background electrolyte, the applied voltage as well as the effect of organic modifier were studied. The migration behavior of nucleotide bases on the MIP column was also compared with that on the bare fused-silica column. The results indicated that the MIP columns demonstrated better recognition properties at a pH range of 6-8. The efficiency (plates/m) at pH 8 for the nonimprinted analyte was 75,300 for cytosine, 50,200 for thymine, and 14,800 for guanine. However, the efficiency for the imprinted analyte, adenine, was quite low. This was evidenced by the broad peak, yielding only 2600 plates/m.

Preparation of monomeric and polymeric β-cyclodextrin functionalized monoliths for rapid isolation and purification of puerarin from Radix puerariae.

PubMed

Lv, Yongqin; Hughes, Timothy C; Hao, Xiaojuan; Mei, Danping; Tan, Tianwei

2011-08-01

Monomeric and epichlorohydrin polymerized β-CD functionalized monoliths were prepared for the rapid isolation and purification of the isoflavonoid puerarin, a well-known traditional Chinese drug, from a crude extract of Radix puerariae (root of the plant Pueraria lobata). Two copolymers poly(isocyanatoethyl methacrylate-co-methyl methacrylate-co-ethylene dimethacrylate) (poly(IEM-co-MMA-co-EDMA)) and poly(glycidyl methacrylate-co-EDMA) (poly(GMA-co-EDMA)) were developed as facile, highly reactive and versatile monolithic matrix. SEM characterization demonstrated that the modified monoliths had homogenous porous structure and morphology. The success of the chemical modification of the monolithic matrix was confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), solid-state (13) C NMR and elemental analysis. It was demonstrated that polymeric β-CD modified monoliths had better separation and selectivity for puerarin, recovering puerarin with a purity of 96% (m%) and a yield of 93% (m%). Compared with poly(glycidyl methacrylate-co-EDMA), poly(isocyanatoethyl methacrylate-co-methyl methacrylate-co-EDMA) monolithic matrix had higher reactivity, which significantly improved the β-CD ligand density and thus the selectivity of the monoliths. Puerarin with a purity of 96% (m%) and with a yield of 89% (m%) was recovered on the monolith. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interface effects on mechanical properties of particle-reinforced composites.

PubMed

Debnath, S; Ranade, R; Wunder, S L; McCool, J; Boberick, K; Baran, G

2004-09-01

Effective bonding between the filler and matrix components typically improves the mechanical properties of polymer composites containing inorganic fillers. The aim of this study was to test the hypothesis that composite flexural modulus, flexure strength, and toughness are directly proportional to filler-matrix interfacial shear strength. The resin matrix component of the experimental composite consisted of a 60:40 blend of BisGMA:TEGDMA. Two levels of photoinitiator components were used: 0.15, and 0.5%. Raman spectroscopy was used to determine degree of cure, and thermogravimetry (TGA) was used to quantify the degree of silane, rubber, or polymer attachment to silica and glass particles. Filler-matrix interfacial shear strengths were measured using a microbond test. Composites containing glass particles with various surface treatments were prepared and the modulus, flexure strength, and fracture toughness of these materials obtained using standard methods. Mechanical properties were measured on dry and soaked specimens. The interfacial strength was greatest for the 5% MPS treated silica, and it increased for polymers prepared with 0.5% initiator compared with 0.15% initiator concentrations. For the mechanical properties measured, the authors found that: (1) the flexural modulus was independent of the type of filler surface treatment, though flexural strength and toughness were highest for the silanated glass; (2) rubber at the interface, whether bonded to the filler and matrix or not, did not improve toughness; (3) less grafting of resin to silanated filler particles was observed when the initiator concentration decreased. These findings suggest that increasing the strength of the bond between filler and matrix will not result in improvements in the mechanical properties of particulate-reinforced composites in contrast to fiber-reinforced composites. Also, contraction stresses in the 0.5 vs 0.15% initiator concentration composites may be responsible for increases in interfacial shear strengths, moduli, and flexural strengths.

Replacement of glass particles by multidirectional short glass fibers in experimental composites: Effects on degree of conversion, mechanical properties and polymerization shrinkage.

PubMed

Bocalon, Anne C E; Mita, Daniela; Narumyia, Isabela; Shouha, Paul; Xavier, Tathy A; Braga, Roberto Ruggiero

2016-09-01

To test the null hypothesis that the replacement of a small fraction of glass particles with random short glass fibers does not affect degree of conversion (DC), flexural strength (FS), fracture toughness (FT) and post-gel polymerization shrinkage (PS) of experimental composites. Four experimental photocurable composites containing 1 BisGMA:1 TEGDMA (by weight) and 60vol% of fillers were prepared. The reinforcing phase was constituted by barium glass particles (2μm) and 0%, 2.5%, 5.0% or 7.5% of silanated glass fibers (1.4mm in length, 7-13μm in diameter). DC (n=4) was obtained using near-FTIR. FS (n=10) was calculated via biaxial flexural test and FT (n=10) used the "single edge notched beam" method. PS at 5min (n=8) was determined using the strain gage method. Data were analyzed by ANOVA/Tukey test (DC, FS, PS) or Kruskal-Wallis/Dunn's test (FT, alpha: 5% for both tests). DC was similar among groups (p>0.05). Only the composite containing 5.0% of fibers presented lower FS than the control (p<0.001). FT increased significantly between the control (1.3±0.17MPam(0.5)) and the composites containing either 5.0% (2.7±0.6MPam(0.5)) or 7.5% of fibers (2.8±0.6MPam(0.5), p<0.001). PS in relation to control was significantly reduced at 2.5% fibers (from 0.81±0.13% to 0.57±0.13%) and further reduced between 5.0% and 7.5% (from 0.42±0.12% to 0.23±0.07%, p<0.001). The replacement of a small fraction of filler particles with glass fibers significantly increased fracture toughness and reduced post-gel shrinkage of experimental composites. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The effects of ethanol on the size-exclusion characteristics of type I dentin collagen to adhesive resin monomers.

PubMed

Chiba, A; Zhou, J; Nakajima, M; Tan, J; Tagami, J; Scheffel, D L S; Hebling, J; Agee, K A; Breschi, L; Grégoire, G; Jang, S S; Tay, F R; Pashley, D H

2016-03-01

During dentin bonding with etch-and-rinse adhesive systems, phosphoric acid etching of mineralized dentin solubilizes the mineral crystallites and replaces them with bound and unbound water. During the infiltration phase of dentin bonding, solvated adhesive resin comonomers are supposed to replace all of the unbound collagen water and polymerize into copolymers. A recently published review suggested that dental monomers are too large to enter and displace water from tightly-packed collagen molecules. Conversely, recent work from the authors' laboratory demonstrated that HEMA and TEGDMA freely equilibrate with water-saturated dentin matrices. However, because adhesive blends are solvated in organic solvents, those solvents may remove enough free water to allow collagen molecules to come close enough to exclude adhesive monomer permeation. The present study analyzed the size-exclusion characteristics of dentin collagen, using a gel permeation-like column chromatography technique, filled with dentin powder instead of Sephadex beads as the stationary phase. The elution volumes of different sized test molecules, including adhesive resin monomers, studied in both water-saturated dentin, and again in ethanol-dehydrated dentin powder, showed that adhesive resin monomers can freely diffuse into both hydrated and dehydrated collagen molecules. Under these in vitro conditions, all free and some of the loosely-bound water seems to have been removed by ethanol. These results validate the concept that adhesive resin monomers can permeate tightly-bound water in ethanol-saturated collagen molecules during infiltration by etch-and-rinse adhesives. It has been reported that collagen molecules in dentin matrices are packed too close together to allow permeation of adhesive monomers between them. Resin infiltration, in this view, would be limited to extrafibrillar spaces. Our work suggests that monomers equilibrate with collagen water in both water and ethanol-saturated dentin matrices. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A resin composite material containing an eugenol derivative for intracanal post cementation and core build-up restoration.

PubMed

Almaroof, A; Rojo, L; Mannocci, F; Deb, S

2016-02-01

To formulate and evaluate new dual cured resin composite based on the inclusion of eugenyl methacrylate monomer (EgMA) with Bis-GMA/TEGDMA resin systems for intracanal post cementation and core build-up restoration of endodontically treated teeth. EgMA was synthesized and incorporated at 5% (BTEg5) or 10% (BTEg10) into dual-cure formulations. Curing properties, viscosity, Tg, radiopacity, static and dynamic mechanical properties of the composites were determined and compared with Clearfil™DC Core-Plus, a commercial dual-cure, two-component composite. Statistical analysis of the data was performed with ANOVA and the Tukey's post-hoc test. The experimental composites were successfully prepared, which exhibited excellent curing depths of 4.9, 4.7 and 4.2 mm for BTEg0, BTEg5 and BTEg10 respectively, which were significantly higher than Clearfil™DC. However, the inclusion of EgMA initially led to a lower degree of cure, which increased when measured at 24 h with values comparable to formulations without EgMA, indicating post-curing. The inclusion of EgMA also lowered the polymerization exotherm thereby reducing the potential of thermal damage to host tissue. Both thermal and viscoelastic analyses confirmed the ability of the monomer to reduce the stiffness of the composites by forming a branched network. The compressive strength of BTEg5 was significantly higher than the control whilst flexural strength increased significantly from 95.9 to 114.8 MPa (BTEg5) and 121.9 MPa (BTEg10). Radiopacity of the composites was equivalent to ∼3 mm Al allowing efficient diagnosis. The incorporation of EgMA within polymerizable formulations provides a novel approach to prepare reinforced resin composite material for intracanal post cementation and core build-up and the potential to impart antibacterial properties of eugenol to endodontic restorations. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Synthesis and application of molecularly imprinted nanoparticles combined ultrasonic assisted for highly selective solid phase extraction trace amount of celecoxib from human plasma samples using design expert (DXB) software.

PubMed

Arabi, Maryam; Ghaedi, Mehrorang; Ostovan, Abbas; Tashkhourian, Javad; Asadallahzadeh, Hamideh

2016-11-01

In this work molecular imprinted nanoparticles (MINPs) was synthesized and applied for ultrasonic assisted solid phase extraction of celecoxib (CEL) from human plasma sample following its combination by HPLC-UV. The MINPs were prepared in a non-covalent approach using methacrylic acid as monomer, CEL as template, ethylene glycol dimethacrylate as cross-linker, and 2,2-azobisisobutyronitrile (AIBN) as the initiator of polymerization. pH, volume of rinsing and eluent solvent and amount of sorbent influence on response were investigated using factorial experimental design, while optimum point was achieved and set as 250mg sorbent, pH 7.0, 1.5mL washing solvent and 2mL eluent by analysis of results according to design expert (DX) software. At above specified conditions, CEL in human plasma with complicated matrices with acceptable high recoveries (96%) and RSD% lower than 10% was quantified and estimated. The proposed MISPE-HPLC-UV method has linear responses among peak area and concentrations of CEL in the range of 0.2-2000μgL(-1), with regression coefficient of 0.98. The limit of detection (LOD) and quantification (LOQ) based on three and ten times of the noise of HPLC peaks correspond to blank solution were 0.08 and 0.18μgL(-1), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Detection of Bisphenol A in aqueous medium by screen printed carbon electrodes incorporating electrochemical molecularly imprinted polymers.

PubMed

Ekomo, Vitalys Mba; Branger, Catherine; Bikanga, Raphaël; Florea, Ana-Mihaela; Istamboulie, Georges; Calas-Blanchard, Carole; Noguer, Thierry; Sarbu, Andrei; Brisset, Hugues

2018-07-30

Electrochemical molecularly imprinted polymers (e-MIPs) were for the first time introduced in screen-printed carbon electrodes (SPCE) as the sensing element for the detection of an organic pollutant. To play this sensing role, a redox tracer was incorporated inside the binding cavities of a cross-linked MIP, as a functional monomer during the synthesis step. Ferrocenylmethyl methacrylate was used for this purpose. It was associated with 4-vinylpyridine as a co-functional monomer and ethylene glycol dimethacrylate as cross-linker for the recognition of the endocrine disruptor, Bisphenol A (BPA), as a target. Microbeads of e-MIP and e-NIP (corresponding non-imprinted polymer) were obtained via precipitation polymerization in acetonitrile. The presence of ferrocene inside the polymers was assessed via FTIR and elemental analysis and the polymers microstructure was characterized by SEM and nitrogen adsorption/desorption experiments. Binding isotherms and batch selectivity experiments evidenced the presence of binding cavities inside the e-MIP and its high affinity for BPA compared to carbamazepine and ketoprofen. e-MIP (and e-NIP) microbeads were then incorporated in a graphite-hydroxyethylcellulose composite paste to prepare SPCE. Electrochemical properties of e-MIP-SPCE revealed a high sensitivity in the presence of BPA in aqueous medium compared to e-NIP-SPCE with a limit of detection (LOD) of 0.06 nM. Selectivity towards carbamazepine and ketoprofen was also observed with the e-MIP-SPCE. Copyright © 2018 Elsevier B.V. All rights reserved.

The improvement of the mechanical properties of PMMA denture base by Al2O3 particles with nitrile rubber

NASA Astrophysics Data System (ADS)

Alhareb, Ahmed Omran; Akil, Hazizan Md; Ahmad, Zainal Arifin

2017-07-01

Poly methyl methacrylate (PMMA) is mostly used for fabrication of denture base by heat-curing technique. Therefore, the purpose of this study is to investigate the effect of Al2O3 filler as toughening particles together with nitrile butadiene rubber (NBR) particles as impact modifier were used to reinforce PMMA denture base materials on the impact strength (IS) and fracture toughness (KIC). PMMA powder was mixed with liquid methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent. The powder components are PMMA, benzoyl peroxide, NBR (5, 7.5 and 10 wt%), and Al2O3 filler (5 wt%) treated by silane. The liquid components are 90% of methyl methacrylate and 10 % ethylene glycol dimethacryate. FTIR analyses confirmed that the Al2O3 filler was successfully treated with silane as coupling agent. The morphology of fracture surfaces was characterized using field emission scanning electron microscopy (FESEM). The results shown that IS and KIC improved significantly when using treated the Al2O3 filler. IS has increased to 56% (8.26 KJ/m2) and 73% (2.77 MPa.m1/2) for KIC when treated Al2O3 filler compared to unreinforced PMMA matrix. Statistical analyses of data results were significantly improved (P<0.05) when using 7.5 wt% NBR with treated Al2O3 filler compared to other the compositions.

Selective extraction based on poly(MAA-VB-EGMDA) monolith followed by HPLC for determination of hordenine in plasma and urine samples.

PubMed

Chen, Yonggang; Meng, Junhua; Zou, Jili; An, Jing

2015-06-01

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity (R(2)  = 0.9992) within 10-2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations <4.7%. Copyright © 2014 John Wiley & Sons, Ltd.

Preparation of solid-phase microextraction fibers by in-mold coating strategy for derivatization analysis of 24-epibrassinolide in pollen samples.

PubMed

Pan, Jialiang; Hu, Yuling; Liang, Tingan; Li, Gongke

2012-11-02

A novel and simple in-mold coating strategy was proposed for the preparation of uniform solid-phase microextraction (SPME) coatings. Such a strategy is based on the direct synthesis of the polymer coating on the surface of a solid fiber using a glass capillary as the mold. The capillary was removed and the polymer with well-controlled thickness could be coated on the silica fiber reproductively. Following the strategy, a new poly(acrylamide-co-ethylene glycol dimethacrylate) (poly(AM-co-EGDMA)) coating was prepared for the preconcentration of 24-epibrassinolide (24-epiBL) from plant matrix. The coating had the enrichment factor of 32 folds, and the extraction efficiency per unit thickness was 5 times higher than that of the commercial polydimethylsiloxane/divinylbenzene (PDMS/DVB) coating. A novel method based on SPME coupled with derivatization and large volume injection-high performance liquid chromatography (LVI-HPLC) was developed for the analysis of 24-epiBL. The linear range was 0.500-20.0 μg/L with the detection limit of 0.13 μg/L. The amounts of endogenous 24-epiBL in rape and sunflower breaking-wall pollens samples were determined with satisfactory recovery (77.8-104%) and reproducibility (3.9-7.9%). The SPME-DE/LVI-HPLC method is rapid, reliable, convenient and applicable for complicated plant samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers.

PubMed

Maksin, Danijela D; Nastasović, Aleksandra B; Milutinović-Nikolić, Aleksandra D; Suručić, Ljiljana T; Sandić, Zvjezdana P; Hercigonja, Radmila V; Onjia, Antonije E

2012-03-30

Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25-70°C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q(max), at pH 1.8 and 25°C was 143 mg g(-1) for PGME2-deta (sample with the highest amino group concentration) while at 70°C Q(max) reached the high value of 198 mg g(-1). Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication and characterization of anisotropic nanofiber scaffolds for advanced drug delivery systems

PubMed Central

Jalani, Ghulam; Jung, Chan Woo; Lee, Jae Sang; Lim, Dong Woo

2014-01-01

Stimuli-responsive, polymer-based nanostructures with anisotropic compartments are of great interest as advanced materials because they are capable of switching their shape via environmentally-triggered conformational changes, while maintaining discrete compartments. In this study, a new class of stimuli-responsive, anisotropic nanofiber scaffolds with physically and chemically distinct compartments was prepared via electrohydrodynamic cojetting with side-by-side needle geometry. These nanofibers have a thermally responsive, physically-crosslinked compartment, and a chemically-crosslinked compartment at the nanoscale. The thermally responsive compartment is composed of physically crosslinkable poly(N-isopropylacrylamide) poly(NIPAM) copolymers, and poly(NIPAM-co-stearyl acrylate) poly(NIPAM-co-SA), while the thermally-unresponsive compartment is composed of polyethylene glycol dimethacrylates. The two distinct compartments were physically crosslinked by the hydrophobic interaction of the stearyl chains of poly(NIPAM-co-SA) or chemically stabilized via ultraviolet irradiation, and were swollen in physiologically relevant buffers due to their hydrophilic polymer networks. Bicompartmental nanofibers with the physically-crosslinked network of the poly(NIPAM-co-SA) compartment showed a thermally-triggered shape change due to thermally-induced aggregation of poly(NIPAM-co-SA). Furthermore, when bovine serum albumin and dexamethasone phosphate were separately loaded into each compartment, the bicompartmental nanofibers with anisotropic actuation exhibited decoupled, controlled release profiles of both drugs in response to a temperature. A new class of multicompartmental nanofibers could be useful for advanced nanofiber scaffolds with two or more drugs released with different kinetics in response to environmental stimuli. PMID:24872702

Preparation of High-Efficiency Cytochrome c-Imprinted Polymer on the Surface of Magnetic Carbon Nanotubes by Epitope Approach via Metal Chelation and Six-Membered Ring.

PubMed

Qin, Ya-Ping; Li, Dong-Yan; He, Xi-Wen; Li, Wen-You; Zhang, Yu-Kui

2016-04-27

A novel epitope molecularly imprinted polymer on the surface of magnetic carbon nanotubes (MCNTs@EMIP) was successfully fabricated to specifically recognize target protein cytochrome c (Cyt C) with high performance. The peptides sequences corresponding to the surface-exposed C-terminus domains of Cyt C was selected as epitope template molecule, and commercially available zinc acrylate and ethylene glycol dimethacrylate (EGDMA) were employed as functional monomer and cross-linker, respectively, to synthesize MIP via free radical polymerization. The epitope was immobilized via metal chelation and six-membered ring formed between the functional monomer and the hydroxyl and amino groups of the epitope. The resulting MCNTs@EMIP exhibited specific recognition ability toward target Cyt C including more satisfactory imprinting factor (about 11.7) than that of other reported imprinting methods. In addition, the MCNTs@EMIP demonstrated a high adsorption amount (about 780.0 mg g(-1)) and excellent selectivity. Besides, the magnetic property of the support material made the processes easy and highly efficient by assistance of an external magnetic field. High-performance liquid chromatography analysis of Cyt C in bovine blood real sample and protein mixture indicated that the specificity was not affected by other competitive proteins, which forcefully stated that the MCNTs@EMIP had potential to be applied in bioseparation area. In brief, this study provided a new protocol to detect target protein in complex sample via epitope imprinting approach and surface imprinting strategy.

Crosslinked polymer nanoparticles containing single conjugated polymer chains

NASA Astrophysics Data System (ADS)

Ponzio, Rodrigo A.; Marcato, Yésica L.; Gómez, María L.; Waiman, Carolina V.; Chesta, Carlos A.; Palacios, Rodrigo E.

2017-06-01

Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly(ethylene glycol dimethacrylate) (pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution.

Room temperature synthesis and binding studies of solution-processable histamine-imprinted microspheres.

PubMed

Romano, Edwin F; Holdsworth, Clovia I; Quirino, Joselito P; So, Regina C

2018-01-01

Accurate quantification of histamine levels in food and in biological samples is important for monitoring the quality of food products and for the detection of pathophysiological conditions. In this study, solution processable histamine-imprinted microspheres were synthesized at 30°C via dilute free radical phototochemical polymerization technique using ethylene glycol dimethacrylate (EGDMA) as the crosslinker and methacrylic acid (MAA) as the monomer. The processability of the resulting polymer is dictated by the monomer feed concentration (eg, 4 wt% 80:20 EGDMA:MAA formulation) and solvent (acetonitrile). Whereas, the particle size is influenced by the monomer feed concentration, the presence of template molecule, and independent of the crosslinker content. Evaluation of the binding performance of the photochemically imprinted polymers (PCP) with different crosslinker content (80 and 90 wt%) indicated that the selective binding capacity was notably higher in PCP-80 (N= 16.0 μmol/g) compared to PCP-90 (N= 10.1 μmol/g) when analyzed via frontal analysis capillary electrophoresis (FACE) using Freundlich isotherm. In addition, PCP-80 microspheres are more selective toward histamine than conventional thermal polymers (CTP-80) prepared at 60°C in the presence of structural analogs such as histidine, imidazole, and tryptamine under cross-rebinding and competitive conditions. These results demonstrated that histamine-selective imprinted polymers can be obtained readily using room temperature photochemical polymerization where these materials can be subsequently used as recognition element for optical-based histamine sensing. Copyright © 2017 John Wiley & Sons, Ltd.

Design and development of molecularly imprinted polymers for the selective extraction of deltamethrin in olive oil: An integrated computational-assisted approach.

PubMed

Martins, Nuno; Carreiro, Elisabete P; Locati, Abel; Ramalho, João P Prates; Cabrita, Maria João; Burke, Anthony J; Garcia, Raquel

2015-08-28

This work firstly addresses the design and development of molecularly imprinted systems selective for deltamethrin aiming to provide a suitable sorbent for solid phase (SPE) extraction that will be further used for the implementation of an analytical methodology for the trace analysis of the target pesticide in spiked olive oil samples. To achieve this goal, a preliminary evaluation of the molecular recognition and selectivity of the molecularly imprinted polymers has been performed. In order to investigate the complexity of the mechanistic basis for template selective recognition in these polymeric matrices, the use of a quantum chemical approach has been attempted providing new insights about the mechanisms underlying template recognition, and in particular the crucial role of the crosslinker agent and the solvent used. Thus, DFT calculations corroborate the results obtained by experimental molecular recognition assays enabling one to select the most suitable imprinting system for MISPE extraction technique which encompasses acrylamide as functional monomer and ethylene glycol dimethacrylate as crosslinker. Furthermore, an analytical methodology comprising a sample preparation step based on solid phase extraction has been implemented using this "tailor made" imprinting system as sorbent, for the selective isolation/pre-concentration of deltamethrin from olive oil samples. Molecularly imprinted solid phase extraction (MISPE) methodology was successfully applied for the clean-up of spiked olive oil samples, with recovery rates up to 94%. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of magnetic molecularly imprinted polymers for selective extraction: determination of citrinin in rice samples by liquid chromatography with UV diode array detection.

PubMed

Urraca, Javier L; Huertas-Pérez, José F; Cazorla, Guillermo Aragoneses; Gracia-Mora, Jesus; García-Campaña, Ana M; Moreno-Bondi, María Cruz

2016-04-01

In this work, we report the synthesis of novel magnetic molecularly imprinted polymers (m-MIPs) and their application to the selective extraction of the mycotoxin citrinin (CIT) from food samples. The polymers were prepared by surface imprinting of Fe3O4 nanoparticles, using 2-naphtholic acid (2-NA) as template molecule, N-3,5-bis(trifluoromethyl)phenyl-N'-4-vinylphenyl urea and methacrylamide as functional monomers and ethyleneglycol dimethacrylate as cross-linker. The resulting material was characterized by transmission electron microscopy (TEM), and X-ray diffraction (XRD) and Fourier transform infrared spectroscopies (FT-IR). The polymers were used to develop a solid-phase extraction method (m-MISPE) for the selective recovery of CIT from rice extracts prior to its determination by HPLC with UV diode array detection. The method involves ultrasound-assisted extraction of the mycotoxin from rice samples with (7:3, v/v) methanol/water, followed by sample cleanup and preconcentration with m-MIP. The extraction (washing and elution) conditions were optimized and their optimal values found to provide CIT recoveries of 94-98 % with relative standard deviations (RSD) less than 3.4 % (n = 3) for preconcentrated sample extracts (5 mL) fortified with the analyte at concentrations over the range 25-100 μg kg(-1). Based on the results, the application of the m-MIPs facilitates the accurate and efficient determination of CIT in rice extracts.

A novel pH-sensitive interferon-β (INF-β) oral delivery system for application in multiple sclerosis.

PubMed

Kondiah, Pierre P D; Tomar, Lomas K; Tyagi, Charu; Choonara, Yahya E; Modi, Girish; du Toit, Lisa C; Kumar, Pradeep; Pillay, Viness

2013-11-18

pH-sensitive microparticles were prepared using trimethyl-chitosan (TMC), poly(ethylene glycol)dimethacrylate (PEGDMA) and methacrylic acid (MAA) by free radical suspension polymerization, for the oral delivery of interferon-β (INF-β). The microparticles were subsequently compressed into a suitable oral tablet formulation. A Box-Behnken experimental design was employed for generating a series of formulations with varying concentrations of TMC (0.05-0.5 g/100 mL) and percentage crosslinker (polyethylene glycol diacrylate) (3-8%, w/w of monomers), for establishment of an optimized TMC-PEGDMA-MAA copolymeric microparticles. For pragmatism, insulin was initially employed as the model peptide for undertaking the preliminary experimentation and the optimized formulation was subsequently evaluated using INF-β. The prepared copolymeric microparticulate system was characterized for its morphological, porositometric and mucoadhesive properties. The optimized microparticles with 0.5 g/100 mL TMC and 3% crosslinker had an INF-β loading efficiency of 53.25%. The in vitro release of INF-β was recorded at 74% and 3% in intestinal (pH 6.8) and gastric (pH 1.2) pH from the oral tablet formulation, respectively. The tablet was further evaluated for plasma concentration of INF-β in the New Zealand White rabbit, and compared to a known subcutaneous formulation. The system showed an astounding effective release profile over 24h with higher INF-β plasma concentrations compared with the subcutaneous injection formulation. Copyright © 2013 Elsevier B.V. All rights reserved.

Epoxy-Based Organogels for Thermally Reversible Light Scattering Films and Form-Stable Phase Change Materials.

PubMed

Puig, Julieta; Dell' Erba, Ignacio E; Schroeder, Walter F; Hoppe, Cristina E; Williams, Roberto J J

2017-03-29

Alkyl chains of β-hydroxyesters synthesized by the capping of terminal epoxy groups of diglycidylether of bisphenol A (DGEBA) with palmitic (C16), stearic (C18), or behenic (C22) fatty acids self-assemble forming a crystalline phase. Above a particular concentration solutions of these esters in a variety of solvents led to supramolecular (physical) gels below the crystallization temperature of alkyl chains. A form-stable phase change material (FS-PCM) was obtained by blending the ester derived from behenic acid with eicosane. A blend containing 20 wt % ester was stable as a gel up to 53 °C and exhibited a heat storage capacity of 161 J/g, absorbed during the melting of eicosane at 37 °C. Thermally reversible light scattering (TRLS) films were obtained by visible-light photopolymerization of poly(ethylene glycol) dimethacrylate-ester blends (50 wt %) in the gel state at room temperature. The reaction was very fast and not inhibited by oxygen. TRLS films consisted of a cross-linked methacrylic network interpenetrated by the supramolecular network formed by the esters. Above the melting temperature of crystallites formed by alkyl chains, the film was transparent due to the matching between refractive indices of the methacrylic network and the amorphous ester. Below the crystallization temperature, the film was opaque because of light dispersion produced by the organic crystallites uniformly dispersed in the material. Of high significance for application was the fact that the contrast ratio did not depend on heating and cooling rates.

Dummy molecularly imprinted microbeads as solid-phase extraction material for selective determination of phthalate esters in water.

PubMed

Özer, Elif Tümay; Osman, Bilgen; Yazıcı, Tuğçe

2017-06-02

The aim of this study was to investigate the usability of newly synthesized dummy molecularly imprinted microbeads (DMIMs) as a solid phase extraction (SPE) material to determine six phthalate esters (PEs) in water by GC-MS analysis. Diethyl phthalate (DEP) was used as a dummy template to prepare poly(ethylene glycol dimethacrylate N-methacryloyl-l-tryptophan methyl ester) [PEMATrp)] DMIMs by using suspension polymerization. The PEMATrp DMIMs were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Firstly, the adsorption capacities of the DMIMs prepared in different template molecule (DEP) to functional monomer (MATrp) ratios were investigated by using DEP solutions in the concentration range of 1-500mg/L at pH 3.0. Styrene and vanillic acid were used to evaluate the selectivity of the prepared DMIMs towards the template molecule (DEP). Then, the best analytical conditions were investigated for the simultaneous determination of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) in aqueous media by using the PEMATrp DMIMs as SPE material. Validation experiments showed that the PEMATrp DMIMs-SPE method had good linearity at 12.5-250.0μg/L (0.988-0.999), good precision (1.2-5.9%), and limits of detection in a range of 0.31-0.41μg/L. Copyright © 2017 Elsevier B.V. All rights reserved.

Functional Circuitry on Commercial Fabric via Textile-Compatible Nanoscale Film Coating Process for Fibertronics.

PubMed

Bae, Hagyoul; Jang, Byung Chul; Park, Hongkeun; Jung, Soo-Ho; Lee, Hye Moon; Park, Jun-Young; Jeon, Seung-Bae; Son, Gyeongho; Tcho, Il-Woong; Yu, Kyoungsik; Im, Sung Gap; Choi, Sung-Yool; Choi, Yang-Kyu

2017-10-11

Fabric-based electronic textiles (e-textiles) are the fundamental components of wearable electronic systems, which can provide convenient hand-free access to computer and electronics applications. However, e-textile technologies presently face significant technical challenges. These challenges include difficulties of fabrication due to the delicate nature of the materials, and limited operating time, a consequence of the conventional normally on computing architecture, with volatile power-hungry electronic components, and modest battery storage. Here, we report a novel poly(ethylene glycol dimethacrylate) (pEGDMA)-textile memristive nonvolatile logic-in-memory circuit, enabling normally off computing, that can overcome those challenges. To form the metal electrode and resistive switching layer, strands of cotton yarn were coated with aluminum (Al) using a solution dip coating method, and the pEGDMA was conformally applied using an initiated chemical vapor deposition process. The intersection of two Al/pEGDMA coated yarns becomes a unit memristor in the lattice structure. The pEGDMA-Textile Memristor (ETM), a form of crossbar array, was interwoven using a grid of Al/pEGDMA coated yarns and untreated yarns. The former were employed in the active memristor and the latter suppressed cell-to-cell disturbance. We experimentally demonstrated for the first time that the basic Boolean functions, including a half adder as well as NOT, NOR, OR, AND, and NAND logic gates, are successfully implemented with the ETM crossbar array on a fabric substrate. This research may represent a breakthrough development for practical wearable and smart fibertronics.

A Functional Monomer Is Not Enough: Principal Component Analysis of the Influence of Template Complexation in Pre-Polymerization Mixtures on Imprinted Polymer Recognition and Morphology

PubMed Central

Golker, Kerstin; Karlsson, Björn C. G.; Rosengren, Annika M.; Nicholls, Ian A.

2014-01-01

In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design. PMID:25391043

Construction of monomer-free, highly crosslinked, water-compatible polymers.

PubMed

Dailing, E A; Lewis, S H; Barros, M D; Stansbury, J W

2014-12-01

Polymeric dental adhesives require the formation of densely crosslinked network structures to best ensure mechanical strength and durability in clinical service. Monomeric precursors to these materials typically consist of mixtures of hydrophilic and hydrophobic components that potentially undergo phase separation in the presence of low concentrations of water, which is detrimental to material performance and has motivated significant investigation into formulations that reduce this effect. We have investigated an approach to network formation based on nanogels that are dispersed in inert solvent and directly polymerized into crosslinked polymers. Monomers of various hydrophilic or hydrophobic characteristics were copolymerized into particulate nanogels bearing internal and external polymerizable functionality. Nanogel dispersions were stable at high concentrations in acetone or, with some exceptions, in water and produced networks with a wide range of mechanical properties. Networks formed rapidly upon light activation and reached high conversion with extremely low volumetric shrinkage. Prepolymerizing monomers into reactive nanostructures significantly changes how hydrophobic materials respond to water compared with networks obtained from polymerizations involving free monomer. The modulus of fully hydrated networks formed solely from nanogels was shown to equal or exceed the modulus in the dry state for networks based on nanogels containing a hydrophobic dimethacrylate and hydrophilic monomethacrylate, a result that was not observed in a hydroxyethyl methacrylate (HEMA) homopolymer or in networks formed from nanogels copolymerized with HEMA. These results highlight the unique approach to network development from nanoscale precursors and properties that have direct implications in functional dental materials. © International & American Associations for Dental Research.

Adsorption separation of carbon dioxide from flue gas by a molecularly imprinted adsorbent.

PubMed

Zhao, Yi; Shen, Yanmei; Ma, Guoyi; Hao, Rongjie

2014-01-01

CO2 separation by molecularly imprinted adsorbent from coal-fired flue gas after desulfurization system has been studied. The adsorbent was synthesized by molecular imprinted technique, using ethanedioic acid, acrylamide, and ethylene glycol dimethacrylate as the template, functional monomer, and cross-linker, respectively. According to the conditions of coal-fired flue gas, the influencing factors, including adsorption temperature, desorption temperature, gas flow rate, and concentrations of CO2, H2O, O2, SO2, and NO, were studied by fixed bed breakthrough experiments. The experimental conditions were optimized to gain the best adsorption performance and reduce unnecessary energy consumption in future practical use. The optimized adsorption temperature, desorption temperature, concentrations of CO2, and gas flow rate are 60 °C, 80 °C, 13%, and 170 mL/min, respectively, which correspond to conditions of practical flue gases to the most extent. The CO2 adsorption performance was nearly unaffected by H2O, O2, and NO in the flue gas, and was promoted by SO2 within the emission limit stipulated in the Chinese emission standards of air pollutants for a thermal power plant. The maximum CO2 adsorption capacity, 0.57 mmol/g, was obtained under the optimized experimental conditions, and the SO2 concentration was 150 mg/m(3). The influence mechanisms of H2O, O2, SO2, and NO on CO2 adsorption capacity were investigated by infrared spectroscopic analysis.

Structure–property relationships in hybrid dental nanocomposite resins containing monofunctional and multifunctional polyhedral oligomeric silsesquioxanes

PubMed Central

Wang, Weiguo; Sun, Xiang; Huang, Li; Gao, Yu; Ban, Jinghao; Shen, Lijuan; Chen, Jihua

2014-01-01

Organic-inorganic hybrid materials, such as polyhedral oligomeric silsesquioxanes (POSS), have the potential to improve the mechanical properties of the methacrylate-based composites and resins used in dentistry. In this article, nanocomposites of methacryl isobutyl POSS (MI-POSS [bears only one methacrylate functional group]) and methacryl POSS (MA-POSS [bears eight methacrylate functional groups]) were investigated to determine the effect of structures on the properties of dental resin. The structures of the POSS-containing networks were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Monofunctional POSS showed a strong tendency toward aggregation and crystallization, while multifunctional POSS showed higher miscibility with the dimethacrylate monomer. The mechanical properties and wear resistance decreased with increasing amounts of MI-POSS, indicating that the MI-POSS agglomerates act as the mechanical weak point in the dental resins. The addition of small amounts of MA-POSS improved the mechanical and shrinkage properties. However, samples with a higher MA-POSS concentration showed lower flexural strength and flexural modulus, indicating that there is a limited range in which the reinforcement properties of MA-POSS can operate. This concentration dependence is attributed to phase separation at higher concentrations of POSS, which affects the structural integrity, and thus, the mechanical and shrinkage properties of the dental resin. Our results show that resin with 3% MA-POSS is a potential candidate for resin-based dental materials. PMID:24550674

Structure-property relationships in hybrid dental nanocomposite resins containing monofunctional and multifunctional polyhedral oligomeric silsesquioxanes.

PubMed

Wang, Weiguo; Sun, Xiang; Huang, Li; Gao, Yu; Ban, Jinghao; Shen, Lijuan; Chen, Jihua

2014-01-01

Organic-inorganic hybrid materials, such as polyhedral oligomeric silsesquioxanes (POSS), have the potential to improve the mechanical properties of the methacrylate-based composites and resins used in dentistry. In this article, nanocomposites of methacryl isobutyl POSS (MI-POSS [bears only one methacrylate functional group]) and methacryl POSS (MA-POSS [bears eight methacrylate functional groups]) were investigated to determine the effect of structures on the properties of dental resin. The structures of the POSS-containing networks were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Monofunctional POSS showed a strong tendency toward aggregation and crystallization, while multifunctional POSS showed higher miscibility with the dimethacrylate monomer. The mechanical properties and wear resistance decreased with increasing amounts of MI-POSS, indicating that the MI-POSS agglomerates act as the mechanical weak point in the dental resins. The addition of small amounts of MA-POSS improved the mechanical and shrinkage properties. However, samples with a higher MA-POSS concentration showed lower flexural strength and flexural modulus, indicating that there is a limited range in which the reinforcement properties of MA-POSS can operate. This concentration dependence is attributed to phase separation at higher concentrations of POSS, which affects the structural integrity, and thus, the mechanical and shrinkage properties of the dental resin. Our results show that resin with 3% MA-POSS is a potential candidate for resin-based dental materials.

A functional monomer is not enough: principal component analysis of the influence of template complexation in pre-polymerization mixtures on imprinted polymer recognition and morphology.

PubMed

Golker, Kerstin; Karlsson, Björn C G; Rosengren, Annika M; Nicholls, Ian A

2014-11-10

In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design.

Determination of eight illegal drugs in human urine by combination of magnetic solid-phase extraction with capillary zone electrophoresis.

PubMed

Chen, Ming-Luan; Suo, Li-Li; Gao, Qiang; Feng, Yu-Qi

2011-08-01

Using magnetite/silica/poly(methacrylic acid-co-ethylene glycol dimethacrylate) (Fe(3)O(4)/SiO(2)/poly(MAA-co-EDMA)) magnetic microspheres, a rapid and high-throughput magnetic solid-phase extraction coupled with capillary zone electrophoresis (MSPE-CZE) method was developed for the determination of illegal drugs (ketamine, amphetamines, opiates, and metabolites). The MSPE of target analytes could be completed within 2 min, and the eight target analytes could be baseline separated within 15 min by CZE with 30 mM phosphate buffer solution (PBS, pH 2.0) containing 15% v/v ACN as background electrolyte. Furthermore, hydrodynamic injection with field-amplified sample stacking (FASS) was employed to enhance the sensitivity of this MSPE-CZE method. Under such optimal conditions, the limits of detection for the eight target analytes ranged from 0.015 to 0.105 μg/mL. The application feasibility of MSPE-CZE in illegal drugs monitoring was demonstrated by analyzing urine samples, and the recoveries of target drugs for the spiked sample ranging from 85.4 to 110.1%. The method reproducibility was tested by evaluating the intra- and interday precisions, and relative standard deviations of <10.3 and 12.4%, respectively, were obtained. To increase throughput of the analysis, a home-made MSPE array that has potential application to the treatment of 96 samples simultaneously was used. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of molecularly imprinted polymers for strychnine by precipitation polymerization and multistep swelling and polymerization and their application for the selective extraction of strychnine from nux-vomica extract powder.

PubMed

Nakamura, Yukari; Matsunaga, Hisami; Haginaka, Jun

2016-04-01

Monodisperse molecularly imprinted polymers for strychnine were prepared by precipitation polymerization and multistep swelling and polymerization, respectively. In precipitation polymerization, methacrylic acid and divinylbenzene were used as a functional monomer and crosslinker, respectively, while in multistep swelling and polymerization, methacrylic acid and ethylene glycol dimethacrylate were used as a functional monomer and crosslinker, respectively. The retention and molecular recognition properties of the molecularly imprinted polymers prepared by both methods for strychnine were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase by liquid chromatography. In addition to shape recognition, ionic and hydrophobic interactions could affect the retention of strychnine in low acetonitrile content. Furthermore, molecularly imprinted polymers prepared by both methods could selectively recognize strychnine among solutes tested. The retention factors and imprinting factors of strychnine on the molecularly imprinted polymer prepared by precipitation polymerization were 220 and 58, respectively, using 20 mM sodium phosphate buffer (pH 6.0)/acetonitrile (50:50, v/v) as a mobile phase, and those on the molecularly imprinted polymer prepared by multistep swelling and polymerization were 73 and 4.5. These results indicate that precipitation polymerization is suitable for the preparation of a molecularly imprinted polymer for strychnine. Furthermore, the molecularly imprinted polymer could be successfully applied for selective extraction of strychnine in nux-vomica extract powder. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of the clean-up efficiency of the solid-phase extraction of rosemary extracts: Application of full-factorial design in hyphenation with Gaussian peak fit function.

PubMed

Meischl, Florian; Kirchler, Christian Günter; Jäger, Michael Andreas; Huck, Christian Wolfgang; Rainer, Matthias

2018-02-01

We present a novel method for the quantitative determination of the clean-up efficiency to provide a calculated parameter for peak purity through iterative fitting in conjunction with design of experiments. Rosemary extracts were used and analyzed before and after solid-phase extraction using a self-fabricated mixed-mode sorbent based on poly(N-vinylimidazole/ethylene glycol dimethacrylate). Optimization was performed by variation of washing steps using a full three-level factorial design and response surface methodology. Separation efficiency of rosmarinic acid from interfering compounds was calculated using an iterative fit of Gaussian-like signals and quantifications were performed by the separate integration of the two interfering peak areas. Results and recoveries were analyzed using Design-Expert® software and revealed significant differences between the washing steps. Optimized parameters were considered and used for all further experiments. Furthermore, the solid-phase extraction procedure was tested and compared with commercial available sorbents. In contrast to generic protocols of the manufacturers, the optimized procedure showed excellent recoveries and clean-up rates for the polymer with ion exchange properties. Finally, rosemary extracts from different manufacturing areas and application types were studied to verify the developed method for its applicability. The cleaned-up extracts were analyzed by liquid chromatography with tandem mass spectrometry for detailed compound evaluation to exclude any interference from coeluting molecules. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography.

PubMed

Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

2013-03-01

Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of <15% (averaged for several metal ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

Molecularly imprinted coated graphene oxide solid-phase extraction monolithic capillary column for selective extraction and sensitive determination of phloxine B in coffee bean.

PubMed

Zhai, Haiyun; Su, Zihao; Chen, Zuanguang; Liu, Zhenping; Yuan, Kaisong; Huang, Lu

2015-03-20

A method was developed to sensitively determine phloxine B in coffee bean by molecularly imprinted polymers (MIPs) coated graphene oxide (GO) solid-phase extraction (GO-MISPE) coupled with high-performance liquid chromatography and laser-induced fluorescence detection (HPLC-LIF). The GO-MISPE capillary monolithic column was prepared by water-bath in situ polymerization, using GO as supporting material, phloxine B, methacrylic acid (MAA), and ethylene dimethacrylate (EDMA) as template, functional monomer, and cross-linker, respectively. The properties of the homemade GO-MISPE capillary monolithic column, including capacity and specificity, were investigated under optimized conditions. The GO-MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). The mean recoveries of phloxine B in coffee bean ranged from 89.5% to 91.4% and the intra-day and inter-day relative standard deviation (RSD) values all ranged from 3.6% to 4.7%. Good linearity was obtained over 0.001-2.0 μg mL(-1) (r=0.9995) with the detection limit (S/N=3) of 0.075 ng mL(-1). Under the selected conditions, enrichment factors of over 90-fold were obtained and extraction on the monolithic column effectively cleaned up the coffee bean matrix. The results demonstrated that the proposed GO-MISPE HPLC-LIF method can be applied to sensitively determine phloxine B in coffee bean. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis of Size-Tunable CO2-Philic Imprinted Polymeric Particles (MIPs) for Low-Pressure CO2 Capture Using Oil-in-Oil Suspension Polymerization.

PubMed

Nabavi, Seyed Ali; Vladisavljević, Goran T; Zhu, Yidi; Manović, Vasilije

2017-10-03

Highly selective molecularly imprinted poly[acrylamide-co-(ethylene glycol dimethacrylate)] polymer particles (MIPs) for CO 2 capture were synthesized by suspension polymerization via oil-in-oil emulsion. Creation of CO 2 -philic, amide-decorated cavities in the polymer matrix led to a high affinity to CO 2 . At 0.15 bar CO 2 partial pressure, the CO 2 /N 2 selectivity was 49 (corresponding to 91% purity of the gas stream after regeneration), and reached 97 at ultralow CO 2 partial pressures. The imprinted polymers showed considerably higher CO 2 uptakes compared to their nonimprinted counterparts, and the maximum equilibrium CO 2 capture capacity of 1.1 mmol g -1 was achieved at 273 K. The heat of adsorption was below 32 kJ mol -1 and the temperature of onset of intense thermal degradation was 351-376 °C. An increase in monomer-to-cross-linker molar ratio in the dispersed phase up to 1:2.5 led to a higher affinity toward CO 2 due to higher density of selective amide groups in the polymer network. MIPs are a promising option for industrial packed and fluidized bed CO 2 capture systems due to large particles with a diameter up to 1200 μm and irregular oblong shapes formed due to arrested coalescence during polymerization, occurring as a result of internal elasticity of the partially polymerized semisolid drops.

Molecularly imprinted polymers as a tool for the study of the 4-ethylphenol metabolic pathway in red wines.

PubMed

Garcia, Deiene; Gomez-Caballero, Alberto; Guerreiro, Antonio; Goicolea, M Aranzazu; Barrio, Ramon J

2015-09-04

A molecularly imprinted polymer (MIP) based methodology is described here for the determination of compounds that belong to the 4-ethylphenol (4EP) metabolic pathway in red wines. To this end, two MIP materials have been developed: a 4EP MIP as a class-selective material to extract phenols that belong to the 4EP metabolic pathway and a coumaric acid (CA) imprinted polymer as a MIP-based stationary phase capable of selectively separating these phenols on HPLC analysis, obtaining clean chromatograms. 4-vinyl pyridine and ethylene glycol dimethacrylate were respectively used as functional monomer and cross-linker for both MIPs. Once polymer compositions were optimised, the 4EP MIP was packed into SPE cartridges for wine sample clean-up and CA MIP was packed into HPLC columns to chromatographically separate the compounds present in the eluates obtained after SPE extraction. The accuracy of the proposed method was tested spiking wine samples with known concentrations of target compounds and subsequently, analytes were quantified by the standard addition method. Registered mean recoveries ranged from 95.2 to 109.2% and RSD values were below 10% in most cases. The described methodology was found to be suitable for the selective extraction and quantification of the compounds that belong to the 4EP metabolic pathway in red wines with minimal matrix effects and could be undoubtedly exploited to monitor 4EP and its precursors in wines. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and characterization of UO(2)(2+)-ion imprinted polymer for selective extraction of UO(2)(2+).

PubMed

Singh, Dhruv K; Mishra, Shraddha

2009-06-30

Ion-imprinted polymers (IIPs) were prepared for uranyl ion (imprint ion) by formation of binary (salicylaldoxime (SALO) or 4-vinylpyridine (VP)) or ternary (salicylaldoxime and 4-vinylpyridine) complex in 2-methoxy ethanol (porogen) following copolymerization with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking monomer using 2,2'-azobisisobutyronitrile as initiator. Control polymers (CPs) were also prepared under identical experimental conditions without using imprint ion. The above synthesized polymers were characterized by surface area measurement, microanalysis and FT-IR analysis techniques. The imprinted polymer formed with ternary complex of UO(2)(2+)-SALO-VP (1:2:2, IIP3) showed quantitative enrichment of uranyl ion from dilute aqueous solution and hence was chosen for detailed studies. The optimal pH for quantitative enrichment is 3.5-6.5. The adsorbed UO(2)(2+) was completely eluted with 10 mL of 1.0 M HCl. The retention capacity of IIP3 was found to be 0.559 mmol g(-1). Further, the distribution ratio and selectivity coefficients of uranium and other selected inorganic ions were also evaluated. Five replicate determinations of 25 microg L(-1) of uranium(VI) gave a mean absorbance of 0.032 with a relative standard deviation of 2.20%. The detection limit corresponding to three times the standard deviation of the blank was found to be 5 microg L(-1). IIP3 was tested for preconcentration of uranium(VI) from ground, river and sea water samples.

An on-line system using ion-imprinted polymer for preconcentration and determination of bismuth in seawater employing atomic fluorescence spectrometry.

PubMed

Felix, Caio S A; Silva, Darllen G; Andrade, Heloysa M C; Riatto, Valeria B; Victor, Mauricio M; Ferreira, Sergio L C

2018-07-01

This work proposes an on-line preconcentration system using ion-imprinted polymer (IIP) for determination of bismuth in seawater employing atomic fluorescence spectrometry (AFS). The polymer was synthesized using 2- (5-bromo-2-pyridylazo) -5-diethylaminophenol (Br-PADAP) for complex formation, ethylene glycol dimethacrylate (EGDMA), cross-linking reagent and methacrylic acid (AMA) reagents, used as the functional monomer, 2,2-azobisisobutyronitrile was used as the radical initiator. The polymer was characterized employing the Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The determination of bismuth was performed employing hydride generation atomic fluorescence spectrometry (HG AFS) and the experimental conditions were optimized using a Box Behnken design involving the factors sample pH, eluent concentration and sodium tetrahydroborate concentration. So, using the optimized conditions the system allows the determination of bismuth with limits of detection and quantification of 26 and 88 ng L -1 , a preconcentration factor of 19.8. All these parameters were determined using a sample volume of 25 mL. The precision expressed as relative standard deviation (RSD%) was 3.7% for a bismuth(III) solution of concentration 0.25 µg L -1 . The system proposed was applied for the determination of bismuth in four seawater samples collected in Salvador City, Bahia State, Brazil. The concentrations obtained varied from 0.38 to 0.45 μg L -1 . The accuracy was evaluated by addition/recovery test, and the recoveries found varied from 92% to 101%. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and characterisation of nano structure lead (II) ion-imprinted polymer as a new sorbent for selective extraction and preconcentration of ultra trace amounts of lead ions from vegetables, rice, and fish samples.

PubMed

Behbahani, Mohammad; Bagheri, Akbar; Taghizadeh, Mohsen; Salarian, Mani; Sadeghi, Omid; Adlnasab, Laleh; Jalali, Kobra

2013-06-01

This paper describes the preparation of new Pb(II)-imprinted polymeric particles using 2-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as the cross-linker, 2,2'- azobisisobutyronitrile as the initiator, diphenylcarbazone as the ligand, acetonitril as the solvent, and Pb(NO(3))(2) as the template ion, through bulk polymerisation technique. The imprinted lead ions were removed from the polymeric matrix using 5 mL of HCl (2 mol.L(-1)) as the eluting solvent. The lead ion concentration was determined by flame atomic absorption spectrometry. Optimum pH for maximum sorption was obtained at 6.0. Sorption and desorption of Pb(II) ions on the IIP particles were quite fast and achieved fully over 5 min. In the proposed method, the maximum sorbent capacity of the ion-imprinted polymer was calculated to be 75.4 mg g(-1). The preconcentration factor, relative standard deviation, and limit of detection of the method were found to be 245, 2.1%, and 0.42 ng mL(-1), respectively. The prepared ion-imprinted polymer particles have an increased selectivity toward Pb(II) ions over a range of competing metal ions with the same charge and similar ionic radius. This ion-imprinted polymer is an efficient solid phase for extraction and preconcentration of lead ions in complex matrixes. For proving that the proposed method is reliable, a wide range of food samples with different and complex matrixes was used. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of Energy Drinks on Discoloration of Silorane and Dimethacrylate-Based Composite Resins.

PubMed

Ahmadizenouz, Ghazaleh; Esmaeili, Behnaz; Ahangari, Zohreh; Khafri, Soraya; Rahmani, Aghil

2016-08-01

This study aimed to assess the effects of two energy drinks on color change (ΔE) of two methacrylate-based and a silorane-based composite resin after one week and one month. Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color values (L*a*b*) of each specimen were measured using a spectrophotometer according to the CIEL*a*b* color system. Ten randomly selected specimens from each composite were then immersed in the two energy drinks (Hype, Red Bull) and artificial saliva (control) for one week and one month. Color was re-assessed after each storage period and ΔE values were calculated. The data were analyzed using the Kruskal Wallis and Mann-Whitney U tests. Filtek Z250 composite showed the highest ΔE irrespective of the solutions at both time points. After seven days and one month, the lowest ΔE values were observed in Filtek Z350XT and Filtek P90 composites immersed in artificial saliva, respectively. The ΔE values of Filtek Z250 and Z350XT composites induced by Red Bull and Hype energy drinks were not significantly different. Discoloration of Filtek P90 was higher in Red Bull energy drink at both time points. Prolonged immersion time in all three solutions increased ΔE values of all composites. However, the ΔE values were within the clinically acceptable range (<3.3) at both time points.

[Aging of silorane- and methacrylate-based composite resins: effects on color and translucency].

PubMed

Liu, Chang; Pan, Jie; Lin, Hong; Shen, Song

2015-10-01

To evaluate the color stability and translucency of silorane-based low shrinkage composite after in vitro aging procedures of thermal cycling and water storage respectively, and to compare with those of conventional methacrylate-based posterior composite. Three light-cured composite resins, dimethacrylate-based composite A (Filtek™ Z350), B (Filtek™ P60) and silorane-based composite C (Filtek™ P90), were tested in this study. Ten specimens (10 mm in diameter, 1 mm in height) of each composite were prepared. The ten specimens in each group were then divided into two subgroups (n = 5). One subgroup underwent thermal cycling [(5.0 ± 0.5)~(55.0 ± 1.0) °C, 10 000 cycles] and the other was stored in 37 C° distilled water for 180 days. With a spectrophotometer, the CIE L * a * b * parameters of the specimens were tested before and after artificial aging against white, medium grey and black backgrounds, respectively. △E, TP and △TP were calculated and data were analyzed using independent-samples t test and partial analysis (P < 0.05). With regard to color stability, silorane-based composite showed color alteration above the clinically acceptable levels (△E > 3.3), and also showed higher △E with a statistically significant difference in comparison with the other composites (B and C) (P < 0.05) after artificial aging. With regard to translucency, composite C showed more alteration compared with composite B (P < 0.05) after thermal cycling. It may be concluded that the silorane-based composite underwent greater alteration with regard to color stability and translucency.

Biodegradable and injectable cure-on-demand polyurethane scaffolds for regeneration of articular cartilage.

PubMed

Werkmeister, J A; Adhikari, R; White, J F; Tebb, T A; Le, T P T; Taing, H C; Mayadunne, R; Gunatillake, P A; Danon, S J; Ramshaw, J A M

2010-09-01

This paper describes the synthesis and characterization of an injectable methacrylate functionalized urethane-based photopolymerizable prepolymer to form biodegradable hydrogels. The tetramethacrylate prepolymer was based on the reaction between two synthesized compounds, diisocyanato poly(ethylene glycol) and monohydroxy dimethacrylate poly(epsilon-caprolactone) triol. The final prepolymer was hydrated with phosphate-buffered saline (pH 7.4) to yield a biocompatible hydrogel containing up to 86% water. The methacrylate functionalized prepolymer was polymerized using blue light (450 nm) with an initiator, camphorquinone and a photosensitizer, N,N-dimethylaminoethyl methacrylate. The polymer was stable in vitro in culture media over the 28 days tested (1.9% mass loss); in the presence of lipase, around 56% mass loss occurred over the 28 days in vitro. Very little degradation occurred in vivo in rats over the same time period. The polymer was well tolerated with very little capsule formation and a moderate host tissue response. Human chondrocytes, seeded onto Cultispher-S beads, were viable in the tetramethacrylate prepolymer and remained viable during and after polymerization. Chondrocyte-bead-polymer constructs were maintained in static and spinner culture for 8 weeks. During this time, cells remained viable, proliferated and migrated from the beads through the polymer towards the edge of the polymer. New extracellular matrix (ECM) was visualized with Masson's trichrome (collagen) and Alcian blue (glycosaminoglycan) staining. Further, the composition of the ECM was typical for articular cartilage with prominent collagen type II and type VI and moderate keratin sulphate, particularly for tissue constructs cultured under dynamic conditions. 2010. Published by Elsevier Ltd. All rights reserved.

Development and characterization of adjustable refractive index scattering epoxy acrylate polymer layers

NASA Astrophysics Data System (ADS)

Eiselt, Thomas; Preinfalk, Jan; Gleißner, Uwe; Lemmer, Uli; Hanemann, Thomas

2016-09-01

This work presents different polymer diffusing films for optical components. In optical applications it is sometimes important to have a film with an adjusted refractive index, scattering properties and a low surface roughness. These diffusing films can be used to increase the efficiency of optical components like organic light emitting diodes (OLEDs). In this study three different epoxy acrylate mixtures containing Syntholux 291 EA, bisphenol a glycerolate dimethacrylate, Sartomer SR 348 L are characterized and optimized with different additives. The adjustable refractive index of the material is achieved with a chemical doping by 9-vinylcarbazole. Titanium nanoparticles in the mixtures generate light scattering and increase the refractive index additionally. To prevent sedimentation and agglomeration of these nanoparticles, a stabilization agent [2-(2-methoxyethoxy)ethoxy]acetic acid is added to the mixture. Other ingredients are a UV-starter and thermal starter for the radical polymerization. A high power stirrer (ultraturrax) is used to mix and disperse all chemical substances together to a homogenous mixture. The viscosity behavior of the mixtures is an important property for the selection of the production method and gets characterized. After the mixing, the monomer mixture is applied on glass substrates by blade coating or screen printing. To initiate the chain growing (polymerization) the produced films are irradiated for 10 minutes long with UV light (UV LED Spot Hönle, 405 nm). After this step a final post bake from the layers in the oven (150°C, 30 min.) is operated. Light transmission measurements (UV-Vis) of the polymer matrix and roughness measurements complement the characterization.

Solid-phase microextraction of phthalate esters in water sample using different activated carbon-polymer monoliths as adsorbents.

PubMed

Lirio, Stephen; Fu, Chung-Wei; Lin, Jhih-Yun; Hsu, Meng-Ju; Huang, Hsi-Ya

2016-07-13

In this study, the application of different activated carbon-polymer (AC-polymer) monoliths as adsorbents for the solid-phase microextraction (SPME) of phthalate esters (PAEs) in water sample were investigated. The activated carbon (AC) was embedded in organic polymers, poly(butyl methacrylate-co-ethylene dimethacrylate) (poly(BMA-EDMA)) or poly(styrene-co-divinylbenzene) (poly(STY-DVB)), via a 5-min microwave-assisted or a 15-min water bath heating polymerization. Preliminary investigation on the performance of the native poly(BMA-EDMA) and poly(STY-DVB) demonstrated remarkable adsorption efficiencies for PAEs. However, due to the strong hydrophobic, π-π, and hydrogen bonding interactions between the analytes and polymers, low extraction recoveries were achieved. In contrast, the presence of AC in native polymers not only enhanced the adsorption efficiencies but also assisted the PAE desorption, especially for AC-poly(STY-DVB) with extraction recovery ranged of 76.2-99.3%. Under the optimized conditions, the extraction recoveries for intra-, inter-day and column-to-column were in the range of 76.5-100.8% (<3.7% RSDs), 77.2-97.6% (<5.6% RSDs) and 75.5-99.7% (<6.2% RSDs), respectively. The developed AC-poly(STY-DVB) monolithic column showed good mechanical stability, which can be reused for more than 30 extraction times without any significant loss in the extraction recoveries of PAEs. The AC-poly(STY-DVB) monolithic column was successfully applied in SPME of PAEs in water sample with extraction recovery ranged of 78.8%-104.6% (<5.5% RSDs). Copyright © 2016 Elsevier B.V. All rights reserved.

Microcontact imprinted quartz crystal microbalance nanosensor for protein C recognition.

PubMed

Bakhshpour, Monireh; Özgür, Erdoğan; Bereli, Nilay; Denizli, Adil

2017-03-01

Detection of protein C (PC) in human serum was performed by quartz crystal microbalance (QCM) based on molecular imprinting technique (MIP). The high-resolution and mass-sensitive QCM based sensor was integrated with high sensitivity and selectivity of the MIP technique. The PC microcontact imprinted (PC-μCIP) nanofilm was prepared on the glass surface. Then, the PC-μCIP/QCM sensor was prepared with 2-hydroxyethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA) and N-methacryloyl l-histidine methylester (MAH) as the functional monomer with copper(II) ions. The polymerization was performed under UV light (100W and 365nm) for 20-25min under nitrogen atmosphere. The characterization studies of QCM sensor were done by observation using atomic force microscopy (AFM), contact angle measurements, ellipsometry and fourier transform infrared spectroscopy (FTIR). Detection of PC was investigated in a concentration range of 0.1-30μg/mL. Selectivity of PC-μCIP and PC non-imprinted/QCM (PC-non-μCIP) sensors for PC determination was investigated by using proteins namely hemoglobin (Hb), human serum albumin (HSA) and fibrinogen solutions. QCM sensor was also used for detection of PC molecules in aqueous solutions and human plasma. The detection limit was determined as 0.01μg/mL for PC analysis. The PC-μCIP/QCM sensor was used for five consecutive adsorption-desorption cycles. According to the results, the PC-μCIP/QCM sensor had obtained high selectivity and sensitivity for detection of PC molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced molecular recognition for imprinted monolithic column containing polyhedral oligomeric silsesquioxanes by dendritic effect of mesoporous molecular sieve scaffolds.

PubMed

Yang, Fang-Fang; Li, Zai-Xuan; Xu, Yu-Jing; Huang, Yan-Ping; Liu, Zhao-Sheng

2018-06-07

The dendritic effect of nano mesoporous molecular sieve was first used to enhance molecular recognition of molecularly imprinted polymers (MIPs)-based polyhedral oligomeric silsesquioxanes (POSS). In this study, the MIPs were made using S-naproxen (S-NAP) as template molecule, 4-vinylpyridine (4-VP) as functional monomer, ethylene glycol dimethacrylate as cross-linker, 1-butyl-3-methylimidazoliumtetrafluoroborate ([BMIM]BF 4 )/DMSO as binary porogens, 1-propylmethacrylate-heptaisobutyl substituted as POSS monomer, and mesoporous molecular sieve (Mobil composition of matter No. 41, MCM-41) as dendritic scaffold. The influence of synthesis parameters on the imprinting effect, including the content of POSS monomer and derivatized MCM-41-MPS, the ratio of template to monomer, and the ratio of binary porogens were also investigated, respectively. The morphology of the polymers was characterized by scanning electron microscopy, nitrogen adsorption, and X-ray powder diffraction. The results showed that POSS&MCM-41-MPS MIP had a stronger imprinting effect with an imprinting factor 6.86, which is approximately 2.4, 2.3, and 3 times than that of POSS MIP, MCM-41-MPS MIP, and conventional MIP, respectively. The increase of affinity might be attributed to impediment of the chain motion of polymer due to improved POSS aggregation and the dipole interaction between the POSS units by introduce of MCM-41-MPS as scaffolds. The resulting POSS&MCM-41-MPS MIP was used as adsorbent for the enrichment of S-NAP in solid-phase extraction with a high recovery of 97.65% and the value of RSD was 0.94%.

Bonding of fibre-reinforced composite post to root canal dentin.

PubMed

Bell, Anna-Maria Le; Lassila, Lippo V J; Kangasniemi, Ilkka; Vallittu, Pekka K

2005-08-01

The aim of this study was to determine bonding properties of two types of fibre-reinforced composite (FRC) posts cemented into root canals of molars. Serrated titanium posts served as reference. Prefabricated carbon/graphite FRC posts with cross-linked polymer matrix and individually formed glass FRC posts with interpenetrating polymer network (IPN) polymer matrix were compared. The crowns of extracted third molars were removed and post space (diameter: 1.5mm) was drilled, etched and bonded. The posts were treated with dimethacrylate adhesive resin, light-polymerized and cemented with a dual-polymerizing composite resin luting cement. After thermocycling (6000x) the samples were cut into discs of thicknesses: 1, 2 and 4mm (n=12/group). Push-out force was measured by pushing the post from one end. Assessment of failure mode was made under a stereomicroscope (1, adhesive failure between post and cement; 2, cohesive failure of post-system; 3, adhesive failure between cement and dentin). The push-out force increased with increased height of dentin disc in all groups (ANOVA, p<0.001). In the 4mm thick dentin discs the individually formed glass FRC posts showed highest push-out force and the difference to that of the titanium posts was significant (ANOVA, p<0.001). The other differences were not statistically significant. None of the individually formed glass FRC posts showed adhesive failures between the post and the cement. Contrary to the other posts, there were no adhesive (post-cement) failures with the individually formed glass FRC posts, suggesting better interfacial adhesion of cement to these posts.

A Selective Surface-Enhanced Raman Scattering Sensor for Mercury(II) Based on a Porous Polymer Material and the Target-Mediated Displacement of a T-Rich Strand

NASA Astrophysics Data System (ADS)

Kang, Y.; Zhang, L.; Zhang, H.; Wu, T.; Du, Y.

2017-05-01

A sensitive and selective surface-enhanced Raman scattering (SERS) sensor for mercury(II) was fabricated based on the target-mediated displacement of a T-rich oligonucleotide strand. A DNA/aptamer duplex was prepared by the hybridization between a tetramethylrhodamine(TMR)-labeled thymine(T)-rich Hg2+-specific aptamer (denoted as TMR-aptamer) and a thiolated adenine-rich capturing DNA. The duplex can be immobilized onto the SERS substrate of the Ag-moiety modified glycidyl methacrylate-ethylene dimethacrylate (denoted as Ag-GMA-EDMA) via self-assembly by the thiol anchor, in which the TMR-aptamer exists in a double-stranded chain. In this case, the label of the TMR moiety approaches the substrate surface and produces a strong SERS signal. Upon the addition of the target, a pair of TMR-aptamers could cooperatively coordinate with Hg2+ to form a stable duplex-like structure mediated by the T-Hg2+-T complex between two adjacent strands, which triggers the release of the TMR-aptamer from the SERS substrate surface, thus drawing the TMR tags away from the substrate with a significant decrease in the SERS signal. This optical sensor shows a sensitive response to Hg2+ in a concentration from 5 nM to 2.0 μM with a detection limit of 2.5 nM. The prepared sensor is negligibly responsive to other metal ions, can be easily regenerated, and shows good performance in real sample analysis.

Selective molecularly imprinted polymer combined with restricted access material for in-tube SPME/UHPLC-MS/MS of parabens in breast milk samples.

PubMed

Souza, Israel D; Melo, Lidervan P; Jardim, Isabel C S F; Monteiro, Juliana C S; Nakano, Ana Marcia S; Queiroz, Maria Eugênia C

2016-08-17

A new molecularly imprinted polymer modified with restricted access material (a hydrophilic external layer), (MIP-RAM) was synthesized via polymerization in situ in an open fused silica capillary. This stationary phase was used as sorbent for in-tube solid phase microextraction (in-tube SPME) to determine parabens in breast milk samples by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Scanning electron micrographs (SEM) illustrate MIP surface modification after glycerol dimethacrylate (hydrophilic monomer) incorporation. The interaction between parabens and MIP-RAM was investigated by Fourier-transform infrared (FTIR) spectroscopy. The Scatchard plot for MIP-RAM presented two linear parts with different slopes, illustrating binding sites with high- and low-affinity. Endogenous compounds exclusion from the MIP-RAM capillary was demonstrated by in-tube SPME/LC-UV assays carried out with blank milk samples. The in-tube SPME/UHPLC-MS/MS method presented linear range from 10 ng mL(-1) (LLOQ) to 400 ng mL(-1) with coefficients of determination higher than 0.99, inter-assay precision with coefficient of variation (CV) values ranging from 2 to 15%, and inter-assay accuracy with relative standard deviation (RSD) values ranging from -1% to 19%. Analytical validation parameters attested that in-tube SPME/UHPLC-MS/MS is an appropriate method to determine parabens in human milk samples to assess human exposure to these compounds. Analysis of breast milk samples from lactating women demonstrated that the proposed method is effective. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemical Sensor Based on Rh(III) Ion-Imprinted Polymer as a New Modifying Agent for Rhodium Determination.

PubMed

Bai, Huiping; Xiong, Caiyun; Wang, Chunqiong; Liu, Peng; Dong, Su; Cao, Qiue

2018-05-01

A rhodium (III) ion carbon paste electrode (CPE) based on an ion imprinted polymer (IIP) as a new modifying agent has been prepared and studied. Rh(III) ion imprinted polymer was synthesized by copolymerization of acrylamide-Rh(III) complex and ethylene glycol dimethacrylate according to the precipitation polymerization. Acrylamide acted as both functional monomer and complexing agent to create selective coordination sites in a cross-linked polymer. The ion imprinted carbon paste electrode (IIP-CPE) was prepared by mixing rhodium IIP-nanoparticles and graphite powder in n-eicosane as an adhesive and then embedding them in a Teflon tube. Amperometric i-t curve method was applied as the determination technique. Several parameters, including the functional monomer, molar ratio of template, monomer and cross-linking agent, the amounts of IIP, the applied potential, the buffer solution and pH have been studied. According to the results, IIP-CPE showed a considerably higher response in comparison with the electrode embedded with non-imprinted polymer (NIP), indicating the formation of suitable recognition sites in the IIP structure during the polymerization stage. The introduced electrode showed a linear range of 1.00×10-8~3.0×10-5 mol·L-1 and detection limit of 6.0 nmol L-1 (S/N = 3). The IIP-CPE was successfully applied for the trace rhodium determination in catalyst and plant samples with RSD of less than 3.3% (n = 5) and recoveries in the range of 95.5~102.5%.

Analysis of malachite green in aquatic products by carbon nanotube-based molecularly imprinted - matrix solid phase dispersion.

PubMed

Wang, Yu; Chen, Ligang

2015-10-01

A simple method based on matrix solid phase dispersion (MSPD) using molecularly imprinted polymers (MIPs) as sorbents for selective extraction of malachite green (MG) from aquatic products was developed. The MIPs were prepared by using carbon nanotube as support, MG as template, methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as crosslinker and methylene chloride as solvent. The MIPs were characterized by Fourier transform infrared spectrometry and transmission electron microscopy. The isothermal adsorption, kinetics absorption and selective adsorption experiments were carried out. We optimized the extraction conditions as follows: the ratio of MIPs to sample was 2:3, the dispersion time was 15min, washing solvent was 4mL 50% aqueous methanol and elution solvent was 3mL methanol-acetic acid (98: 2, v/v). Once the MSPD process was completed, the MG extracted from aquatic products was determined by high performance liquid chromatography. The detection limit of MG was 0.7μgkg(-1). The relative standard deviations of intra-day and inter-day were obtained in the range of 0.9%-4.7% and 3.4%-9.8%, respectively. In order to evaluate the applicability and reliability of the proposed method, it was applied to determine MG in different aquatic products samples including fish, shrimp, squid and crabs. The satisfied recoveries were in the range of 89.2%-104.6%. The results showed that this method is faster, simpler and makes extraction and purification in the same system. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic poly(2-hydroxyethyl methacrylate) microspheres for affinity purification of monospecific anti-p46 kDa/Myo1C antibodies for early diagnosis of multiple sclerosis patients

PubMed Central

Hlídková, Helena; Kit, Yurii; Antonyuk, Volodymyr; Myronovsky, Severyn; Stoika, Rostyslav

2017-01-01

The aim of the present study is to develop new magnetic polymer microspheres with functional groups available for easy protein and antibody binding. Monodisperse macroporous poly(2-hydroxyethyl methacrylate) (PHEMA-COOH) microspheres ~4 µm in diameter and containing ∼1 mmol COOH/g were synthesized by multistep swelling polymerization of 2-hydroxyethyl methacrylate (HEMA), ethylene dimethacrylate (EDMA), and 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA), which was followed by MCMEMA hydrolysis. The microspheres were rendered magnetic by precipitation of iron oxide inside the pores, which made them easily separable in a magnetic field. Properties of the resulting magnetic poly(2-hydroxyethyl methacrylate) (mgt.PHEMA) particles with COOH functionality were examined by scanning and transmission electron microscopy (SEM and TEM), static volumetric adsorption of helium and nitrogen, mercury porosimetry, Fourier transform infrared (FTIR) and atomic absorption spectroscopy (AAS), and elemental analysis. Mgt.PHEMA microspheres were coupled with p46/Myo1C protein purified from blood serum of multiple sclerosis (MS) patients, which enabled easy isolation of monospecific anti-p46/Myo1C immunoglobulin G (IgG) antibodies from crude antibody preparations of mouse blood serum. High efficiency of this approach was confirmed by SDS/PAGE, Western blot, and dot blot analyses. The newly developed mgt.PHEMA microspheres conjugated with a potential disease biomarker, p46/Myo1C protein, are thus a promising tool for affinity purification of antibodies, which can improve diagnosis and treatment of MS patients. PMID:28351895

Preparation of molecular imprinted polymers using bi-functional monomer and bi-crosslinker for solid-phase extraction of rutin.

PubMed

Zeng, Huan; Wang, Yuzhi; Liu, Xiaojie; Kong, Jinhuan; Nie, Chan

2012-05-15

Molecular imprinted polymers (MIPs) were prepared using rutin as the template, different reagents as the functional monomer and different reagents as the cross-linker by solution polymerization. Several parameters that would influence the performance of MIPs were investigated including the type of functional monomer (single or double) and cross-linker (single or double), and the molar ratio of the template, the functional monomer and the cross-linker. The optimum synthesis conditions of MIPs were found to be bi-monomers (acrylamide-co-2-vinyl pyridine, 3:1) and bi-crosslinker (ethylene glycol dimethacrylate-co-divinylbenzene, 3:1). The ratio of the template, the functional monomer and the cross-linker was found to be 1:6:20. MIPs synthesized under these conditions were filled into the cartridges as the adsorbents of solid-phase extraction (SPE). A competition test was conducted to authenticate the selectivity and the specificity of molecularly imprinted solid-phase extraction (MISPE) for rutin using the mixture solution of standard rutin and its structural analogs including quercetin, naringenin and kaempferol. Compared with purchased SPE including C(18), silica and PCX, MISPE showed better selectivity and enrichment property for rutin in the extracted solutions of Chinese medicinal plants than any others. The mean recoveries were 85.93% (RSD: 3.04%, n=3) for Saururus chinensis (Lour.) Bail and 88.61% (RSD: 3.36%, n=3) for Flos Sophorae, respectively, which indicated that the optimized rutin-MIPs possess the value of practical application. Copyright © 2012 Elsevier B.V. All rights reserved.

Tensile Bond Strength between Soft Liners and Two Chemically Different Denture Base Materials: Effect of Thermocycling.

PubMed

Tugut, Faik; Coskun, Mehmet Emre; Dogan, Derya Ozdemir; Kirmali, Omer; Akin, Hakan

2016-06-01

The bond strength of soft denture liner to a recently introduced denture base resin after thermocycling has not been compared to traditional denture base materials. The objective of this study was to investigate the effects of thermocycling on the tensile bond strength of soft denture liners to two chemically different denture base resins, polymethyl methacrylate (PMMA) and urethane dimethacrylate (UDMA). A total of 48 PMMA and UDMA tensile test specimens were fabricated by attaching two different soft denture liners (Molloplast-B, Permaflex) according to the manufacturers' instructions and assigned to two groups. Half of the specimens for each group were stored in water for 1 week, and the other half were thermocycled (5000 cycles) between baths of 5°C and 55°C. Specimens were mounted on a universal testing machine with a 5 mm/min crosshead speed. The data were analyzed with three-way ANOVA and post hoc Tukey-Kramer multiple comparisons tests (α = 0.05). The highest bond strength was measured in the specimens from the UDMA/Molloplast groups, and the lowest was seen in the PMMA/Permaflex group. No significant difference in bond strength was detected in PMMA/Permaflex groups after thermocycling (p = 0.082), whereas other groups exhibited significant differences after thermocycling (p < 0.05). Thermocycling decreased the bond strength values in both the PMMA and UDMA groups. Regardless of types of soft liners, PMMA specimens presented lower bond strength values than UDMA specimens, both before and after thermocycling. © 2015 by the American College of Prosthodontists.

[Rapid fabrication of molecularly imprinted polymer fibers for solid phase microextraction of bisphenol A].

PubMed

Hu, Mei; Zhang, Yijun; Yang, Jinghua; Zhou, Xiaomao; Wei, Zhuqing; Ding, Xiaoqing; Zhang, Yuping

2015-02-01

The rapid preparation of molecularly imprinted polymer (MIP) fibers was reported using bisphenol A (BPA) as the template molecular, acetonitrile (ACN) as the porogenic solvent, α-methacrylic acid (MAA) as the functional monomer, ethylene dimethacrylate (EDMA) as the crosslinker, and azodiisobutyronitrile (AIBN) as the thermal initiator. It was carried out within a capillary of 530 µm inner diameter (I. D.) by microwave irradiation in 7 min. The resulted BPA-MIP fibers were pushed out from the capillary, eluted in a vial and inserted in the capillary again followed by the application of the solid phase microextraction (SPME) procedure. The extraction performance was investigated in detail by varying the molar ratios between the template and the monomer (BPA/MAA), the concentration of NaCl, the extraction and desorption time, the pH value and the desorption solvents. The selectivity of the prepared MIP and non-molecularly imprinted polymer (NIP) fibers was comparatively evaluated by selecting two structurally-related compounds, phenol (P) and 4-phenylphenol (PP), and non-analogue dicyandiamide (DCD). The established method was successfully applied for the pretreatment and determination of BPA from beverage samples coupled to high performance liquid chromatography (HPLC). Under the optimal conditions, the linear range of BPA was 10-400 µg/L; the detection limit (LOD) was 0.45 µg/L and the recoveries spiked in the mineral water were 88.4%-102. 8%. The results demonstrated that the developed method can determine BPA in real samples with some advantages of simple pretreatment, rapid analysis, low limit of detection and low consumption of materials.

Rapid Detection of Melamine in Tap Water and Milk Using Conjugated "One-Step" Molecularly Imprinted Polymers-Surface Enhanced Raman Spectroscopic Sensor.

PubMed

Hu, Yaxi; Lu, Xiaonan

2016-05-01

An innovative "one-step" sensor conjugating molecularly imprinted polymers and surface enhanced Raman spectroscopic-active substrate (MIPs-SERS) was investigated for simultaneous extraction and determination of melamine in tap water and milk. This sensor was fabricated by integrating silver nanoparticles (AgNPs) with MIPs synthesized by bulk polymerization of melamine (template), methacrylic acid (functional monomer), ethylene glycol dimethacrylate (cross-linking agent), and 2,2'-azobisisobutyronitrile (initiator). Static and kinetic adsorption tests validated the specific affinity of MIPs-AgNPs to melamine and the rapid adsorption equilibration rate. Principal component analysis segregated SERS spectral features of tap water and milk samples with different melamine concentrations. Partial least squares regression models correlated melamine concentrations in tap water and skim milk with SERS spectral features. The limit of detection (LOD) and limit of quantification (LOQ) of melamine in tap water were determined as 0.0019 and 0.0064 mmol/L, while the LOD and LOQ were 0.0165 and 0.055 mmol/L for the determination of melamine in skim milk. However, this sensor is not ideal to quantify melamine in tap water and skim milk. By conjugating MIPs with SERS-active substrate (that is, AgNPs), reproducibility of SERS spectral features was increased, resulting in more accurate detection. The time required to determine melamine in tap water and milk were 6 and 25 min, respectively. The low LOD, LOQ, and rapid detection confirm the potential of applying this sensor for accurate and high-throughput detection of melamine in tap water and milk. © 2016 Institute of Food Technologists®

Highly sensitive determination of polycyclic aromatic hydrocarbons in ambient air dust by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction.

PubMed

Krupadam, Reddithota J; Bhagat, Bhagyashree; Khan, Muntazir S

2010-08-01

A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry (GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction (SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L(-1) (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials--powdered activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)--and it was shown that the extraction capacity of the MIP was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L(-1) for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic PAHs in air dust of industrial zones and satisfactory results were obtained.

Molecularly imprinted solid-phase extraction for the selective determination of bromhexine in human serum and urine with high performance liquid chromatography.

PubMed

Javanbakht, Mehran; Namjumanesh, Mohammad Hadi; Akbari-Adergani, Behrouz

2009-11-15

In this work, a novel method is described for the determination of bromhexine in biological fluids using molecularly imprinted solid-phase extraction as the sample cleanup technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and bromhexine as the template molecule. The novel imprinted polymer was used as a solid-phase extraction sorbent for the extraction of bromhexine from human serum and urine. Various parameters affecting the extraction efficiency of the polymer have been evaluated. The optimal conditions for molecularly imprinted solid-phase extraction (MISPE) consisted of conditioning 1 mL methanol and 1 mL of deionized water at neutral pH, loading of 5 mL of the water sample (25 microg L(-1)) at pH 6.0, washing using 2 mL acetonitrile/acetone (1/4, v/v) and elution with 3x 1 mL methanol/acetic acid (10/1, v/v). The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of bromhexine. Results from the HPLC analyses showed that the calibration curve of bromhexine using MIP from human serum and urine is linear in the ranges of 0.5-100 and 1.5-100 microg L(-1) with good precisions (3.3% and 2.8% for 5.0 microg L(-1)), respectively. The recoveries for serum and urine samples were higher than 92%.

The syntheses and characterization of molecularly imprinted polymers for the controlled release of bromhexine.

PubMed

Azodi-Deilami, Saman; Abdouss, Majid; Javanbakht, Mehran

2011-05-01

Imprinted polymers are now being increasingly considered for active biomedical uses such as drug delivery. In this work, the use of molecularly imprinted polymers (MIPs) in designing new drug delivery devices was studied. Imprinted polymers were prepared from methacrylic acid (functional monomer), ethylene glycol dimethacrylate (cross-linker), and bromhexine (as a drug template) using bulk polymerization method. The influence of the template/functional monomer proportion and pH on the achievement of MIPs with pore cavities with a high enough affinity for the drug was investigated. The polymeric devices were further characterized by FT-IR, thermogravimetric analysis, scanning electron microscopy, and binding experiments. The imprinted polymers showed a higher affinity for bromhexine and a slower release rate than the non-imprinted polymers. The controlled release of bromhexine from the prepared imprinted polymers was investigated through in vitro dissolution tests by measuring absorbance at λ (max) of 310 nm by HPLC-UV. The dissolution media employed were hydrochloric acid at the pH level of 3.0 and phosphate buffers, at pH levels of 6.0 and 8.0, maintained at 37.0 and 25.0 ± 0.5 °C. Results from the analyses showed the ability of MIP polymers to control the release of bromhexine In all cases The imprinted polymers showed a higher affinity for bromhexine and a slower release rate than the non-imprinted polymers. At the pH level of 3.0 and at the temperature of 25 °C, slower release of bromhexine imprinted polymer occurred.

The suitability of DEAE-Cl active groups on customized poly(GMA-co-EDMA) continuous stationary phase for fast enzyme-free isolation of plasmid DNA.

PubMed

Danquah, Michael K; Forde, Gareth M

2007-06-15

The creation of a commercially viable and a large-scale purification process for plasmid DNA (pDNA) production requires a whole-systems continuous or semi-continuous purification strategy employing optimised stationary adsorption phase(s) without the use of expensive and toxic chemicals, avian/bovine-derived enzymes and several built-in unit processes, thus affecting overall plasmid recovery, processing time and economics. Continuous stationary phases are known to offer fast separation due to their large pore diameter making large molecule pDNA easily accessible with limited mass transfer resistance even at high flow rates. A monolithic stationary sorbent was synthesised via free radical liquid porogenic polymerisation of ethylene glycol dimethacrylate (EDMA) and glycidyl methacrylate (GMA) with surface and pore characteristics tailored specifically for plasmid binding, retention and elution. The polymer was functionalised with an amine active group for anion-exchange purification of pDNA from cleared lysate obtained from E. coli DH5alpha-pUC19 pellets in RNase/protease-free process. Characterization of the resin showed a unique porous material with 70% of the pores sizes above 300 nm. The final product isolated from anion-exchange purification in only 5 min was pure and homogenous supercoiled pDNA with no gDNA, RNA and protein contamination as confirmed with DNA electrophoresis, restriction analysis and SDS page. The resin showed a maximum binding capacity of 15.2 mg/mL and this capacity persisted after several applications of the resin. This technique is cGMP compatible and commercially viable for rapid isolation of pDNA.

A novel photodynamic therapy-based drug delivery system layered on a stent for treating cholangiocarcinoma.

PubMed

Liang, Po-Chin; Huang, Kai-Wen; Tung, Chien-Chih; Chang, Ming-Chu; Chang, Fuh-Yu; Wong, Jau-Min; Chang, Yu-Ting

2017-11-22

This study aimed to investigate the drug delivery efficacy and bio-effectiveness of a novel photodynamic therapy (PDT)-matrix drug delivery system for cholangiocarcinoma (CCA). Metallic stents were coated with polyurethane (PU) as the first layer. A 2-hydroxyethyl methacrylate (2-HEMA)/ethylene glycol dimethacrylate (EGDMA)/benzoyl peroxide (BPO) layer and a poly(ethylene-co-vinyl acetate) (PEVA)/poly(n-butyl methacrylate) (PBMA)/polyvinylpyrrolidone K30 (K30) layer containing various concentrations of Photofrin were then incorporated onto the stent as the second and third layers. After incubating the layered membranes with cultured CCA cell line, the release of Photofrin, cell viability, the intracellular uptake of Photofrin, reactive oxygen species (ROS) generation, and apoptosis were determined. Using a single-layer diffusion model, the maximum release of Photofrin from the 5 to 10% K30 formulas was 80 and 100%, respectively, after 24 h. When using the multiple-layer diffusion model, the released Photofrin showed an initial burst of the loading dose from the PEVA/PBMA/K30 layer. In the immobilized model, less than 5% of the Photofrin from the 2-HEMA/EGDMA/BPO layer was released over the 24-h period. Cell viability decreased linearly with increasing Photofrin concentrations, and ROS generation and apoptosis were shown to increase significantly with increasing Photofrin concentrations, until the concentration of Photofrin reached a saturation point of 1.5 μg/ml. This new, multiple-layered, PDT-based stent with dual-release mechanisms is a promising treatment for CCA and cancer-related ductal stenosis.

Fractography and Mechanical Properties of Urethane Dimethacrylate Dental Composites Reinforced with Glass Nanoparticles.

PubMed

M, Monfared; Me, Bahrololoom

2016-12-01

Dental resin composites are becoming prevalent in restorative dentistry and have almost replaced amalgam nowadays. Consequently, their mechanical properties and durability are critical. The aim of this study was to produce Pyrex glass nano-particles by wet milling process and use them as reinforcement in dental resins for anterior restorations and then examination of fractographic properties of these composites. The glass nano-particles were achieved via wet milling. The surface of the particles was modified with 3-(Trimethoxysilyl) propyl methacrylate (γ-MPTMS) silane in order to improve their surface. Fourier transform infra-red (FTIR) analysis showed that the silane groups provided double bonds to the surface of the particles and prevented agglomeration. Then, the composite resins were made with different weight percentages of Pyrex glass. The mechanical properties of samples flexural test were evaluated. The required energy for fracture of the specimens was achieved via this test. The fracture surfaces of the samples were analyzed using a scanning electron microscope (SEM) in order to explain the mechanisms of fracture. The results and analysis showed that increasing the glass nano-particles mass fraction had a great effect on mechanical properties of the composites due to the mechanisms of crack propagation and crack deflection as well as preventing void formation. The effective energy dissipation mechanisms such as crack pinning and deflection, was observed in SEM micrographs. Void formation in the low filler content composite is one of the mechanisms to decrease the energy required for fracture of these composites and eventually weaken them.

Fractography and Mechanical Properties of Urethane Dimethacrylate Dental Composites Reinforced with Glass Nanoparticles

PubMed Central

M*, Monfared; ME, Bahrololoom

2016-01-01

Statement of Problem: Dental resin composites are becoming prevalent in restorative dentistry and have almost replaced amalgam nowadays. Consequently, their mechanical properties and durability are critical. Objectives: The aim of this study was to produce Pyrex glass nano-particles by wet milling process and use them as reinforcement in dental resins for anterior restorations and then examination of fractographic properties of these composites. Materials and Methods: The glass nano-particles were achieved via wet milling. The surface of the particles was modified with 3-(Trimethoxysilyl) propyl methacrylate (γ-MPTMS) silane in order to improve their surface. Fourier transform infra-red (FTIR) analysis showed that the silane groups provided double bonds to the surface of the particles and prevented agglomeration. Then, the composite resins were made with different weight percentages of Pyrex glass. The mechanical properties of samples flexural test were evaluated. The required energy for fracture of the specimens was achieved via this test. The fracture surfaces of the samples were analyzed using a scanning electron microscope (SEM) in order to explain the mechanisms of fracture. Results: The results and analysis showed that increasing the glass nano-particles mass fraction had a great effect on mechanical properties of the composites due to the mechanisms of crack propagation and crack deflection as well as preventing void formation. The effective energy dissipation mechanisms such as crack pinning and deflection, was observed in SEM micrographs. Conclusions: Void formation in the low filler content composite is one of the mechanisms to decrease the energy required for fracture of these composites and eventually weaken them. PMID:28959761

Synthesis, characterization and analytical applications of Ni(II)-ion imprinted polymer

NASA Astrophysics Data System (ADS)

Singh, D. K.; Mishra, Shraddha

2010-10-01

Ion recognition-based separation techniques have received much attention because of their high selectivity for target ions. In this study, we have prepared a novel ion imprinted polymer (IIP) to remove nickel ions with high selectivity. The imprinted polymer was prepared by copolymerization of 2-hydroxy ethyl methacrylate (HEMA) with nickel vinylbenzoate complex in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinker. The polymerization was carried out in bulk with free radical initiation using 2-methoxy ethanol as a solvent and porogen. The adsorbed nickel was completely eluted with 15 mL of 1 M HCl. Control polymer was also prepared by similar experimental conditions without using imprint ion. The above synthesized polymers were characterized by surface area measurements, FT-IR, microanalysis and SEM analysis. The adsorption capacity of IIP and CP was found to be 1.51 and 0.65 mmol g -1, respectively. The optimal pH for quantitative enrichment was 6.5. Nature of eluent, eluent concentration and eluent volume were also studied. The relative selectivity factor ( αr) values of Ni(II)/Zn(II), Ni(II)/Cu(II) and Ni(II)/Co(II) were 78.6, 111.1 and 91.6, respectively. Five replicate determinations of 30 μg L -1 of Ni(II) gave a mean absorbance of 0.067 with a relative standard deviation of 1.06%. The lowest concentration determined by GTA-AAS below which the recovery becomes non-quantitative is 6 μg L -1. IIP was tested for removal of Ni(II) from sea water sample.

Microfluidic approaches for the fabrication of gradient crosslinked networks based on poly(ethylene glycol) and hyperbranched polymers for manipulation of cell interactions

PubMed Central

Pedron, S; Peinado, C; Bosch, P; Benton, J A; Anseth, K S

2011-01-01

High-throughput methods allow rapid examination of parameter space to characterize materials and develop new polymeric formulations for biomaterials applications. One limitation is the difficulty of preparing libraries and performing high-throughput screening with conventional instrumentation and sample preparation. Here, we describe the fabrication of substrate materials with controlled gradients in composition by a rapid method of micromixing followed by a photopolymerization reaction. Specifically, poly(ethylene glycol) dimethacrylate was copolymerized with a hyperbranched multimethacrylate (P1000MA or H30MA) in a gradient manner. The extent of methacrylate conversion and the final network composition were determined by near-infrared spectroscopy, and mechanical properties were measured by nanoindentation. A relationship was observed between the elastic modulus and network crosslinking density. Roughness and hydrophilicity were increased on surfaces with a higher concentration of P1000MA. These results likely relate to a phase segregation process of the hyperbranched macromer that occurs during the photopolymerization reaction. On the other hand, the decrease in the final conversion in H30MA polymerization reactions was attributed to the lower termination rate as a consequence of the softening of the network. Valvular interstitial cell attachment was evaluated on these gradient substrates as a demonstration of studying cell morphology as a function of the local substrate properties. Data revealed that the presence of P1000MA affects cell–material interaction with a higher number of adhered cells and more cell spreading on gradient regions with a higher content of the multifunctional crosslinker. PMID:21105168

UV-curable gel formulations: Potential drug carriers for the topical treatment of nail diseases.

PubMed

Kerai, Laxmi Valji; Hilton, Stephen; Murdan, Sudaxshina

2015-08-15

Nail diseases are common, cause significant distress and treatments are far from successful. Our aim was to investigate the potential of UV-curable gels - currently used as cosmetics - as topical drug carriers for their treatment. These formulations have a long residence on the nail, which is expected to increase patient compliance and the success of topical therapy. The gels are composed of the diurethane dimethacrylate, ethyl methacrylate, 2-hydroxy-2-methylpropiophenone, an antifungal drug (amorolfine HCl or terbinafine HCl) and an organic liquid (ethanol or NMP) as drug solvent. Following its application to a substrate and exposure to a UVA lamp for 2 min, the gel polymerises and forms a smooth, glossy and amorphous film, with negligible levels of residual monomers. No drug-polymer interactions were found and drug loading did not affect the film's properties, such as thickness, crystallinity and transition temperatures. In contrast, the organic solvent did influence the film's properties; NMP-containing films had lower glass transition temperatures, adhesion and water resistance than ethanol-based ones. Water-resistance being a desired property, ethanol-based formulations were investigated further for stability, drug release and ungual permeation. The films were stable under accelerated stability testing conditions. Compared to terbinafine, amorolfine was released to a greater extent, had a higher ungual flux, but a lower concentration in the nailplate. However, both drugs were present at considerably high levels in the nail when their MICs are taken into account. We thus conclude that UV-curable gels are promising candidates as topical nail medicines. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Towards field detection of polycyclic aromatic hydrocarbons (PAHs) in environment water using a self-assembled SERS sensor

NASA Astrophysics Data System (ADS)

Yan, Xia; Shi, Xiaofeng; Yang, Jie; Zhang, Xu; Jia, Wenjie; Ma, Jun

2017-10-01

A self-assembled surface enhanced Raman scattering (SERS) sensor is reported in this paper. To achieve high sensitivity, a high sensitive SERS substrate and a high efficient self-constructed light path were made. The SERS substrate was composed by gold nanoparticles (AuNPs, pH=13), glycidyl methacrylate-ethylene dimethacrylate (GMA-EDMA) porous material and syringe filter. The substrate had a good repeatability, and the relative standard deviation (RSD) of the same substrate was less than 5%. The efficiency of the self-constructed light path is about two times better than RPB Y type reflection fiber when the energy density was roughly equal on samples. The size of the SERS sensor is 350×300×180 mm and the weight is 15 kg. Its miniaturization and portable can comply with the requirements of field detection. Besides, it has good sensitivity, stability and selectivity. For lab experiments, strong enhancements of Raman scattering from organic pollutant polycyclic aromatic hydrocarbons (PAHs) molecules were exhibited. The dependences of SERS intensities on concentrations of PAHs were investigated, and the results indicated that they revealed a satisfactory linear relationship in low concentrations. The limits of detection (LODs) of PAHs phenanthrene and fluorene are 8.3×10-10 mol/L and 7.1×10-10 mol/L respectively [signal to noise ratio (S/N) =3]. Based on this SERS sensor, signals of benzo (a) pyrene and pyrene were found in environmental water and the sensor would be an ideal candidate for field detection of PAHs.