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Sample records for acid pla polymer

  1. Polymer Film-Based Screening and Isolation of Polylactic Acid (PLA)-Degrading Microorganisms.

    PubMed

    Kim, Mi Yeon; Kim, Changman; Moon, Jungheun; Heo, Jinhee; Jung, Sokhee P; Kim, Jung Rae

    2017-02-28

    Polylactic acid (PLA) has been highlighted as an alternative renewable polymer for the replacement of petroleum-based plastic materials, and is considered to be biodegradable. On the other hand, the biodegradation of PLA by terminal degraders, such as microorganisms, requires a lengthy period in the natural environment, and its mechanism is not completely understood. PLA biodegradation studies have been conducted using mainly undefined mixed cultures, but only a few bacterial strains have been isolated and examined. For further characterization of PLA biodegradation, in this study, the PLA-degrading bacteria from digester sludge were isolated and identified using a polymer film-based screening method. The enrichment of sludge on PLA granules was conducted with the serial transference of a subculture into fresh media for 40 days, and the attached biofilm was inoculated on a PLA film on an agar plate. 3D optical microscopy showed that the isolates physically degraded the PLA film due to bacterial degradation. 16S rRNA gene sequencing identified the microbial colonies to be Pseudomonas sp. MYK1 and Bacillus sp. MYK2. The two isolates exhibited significantly higher specific gas production rates from PLA biodegradation compared with that of the initial sludge inoculum.

  2. Polymer blends of polylactic acid (PLA) and polybutylene succinate-adipate

    NASA Astrophysics Data System (ADS)

    Ma, Wenguang

    A series of blends consisting of polylactic acid (PLA) and aliphatic succinate polyester (BionolleRTM #3000) had been prepared and investigated. The results of mechanical property investigations showed that using 20 wt% Bionolle#3000 can significantly increase the toughness of PLA. BionolleRTM #3000 also reduces the physical aging rate of PLA so blends remain tough longer. Conversely, the stiffness of BionolleRTM #3000 can be significantly increased by blending in PLA. DMA and DSC results show that PLA/BionolleRTM 3000 blends are not thermodynamically miscible, but are compatible blends. Studies have also been performed to determine the amount and rate of aerobic biodegradation of PLA/aliphatic succinate polyester blends in biologically active composting, enzymatic, and soil environments. The changes in molecular weight, molecular structure and thermal properties in the composting environment were also studied by GPC, NMR and DSC analyses. The research results showed BionolleRTM #3000 had a high degradation rate, while PLA had a low degradation rate. PLA/BionolleRTM #3000 blends had moderate degradation rates that increased with BionolleRTM #3000 content. The melt flow behavior of PLA/BionolleRTM #3000 blends has been studied by capillary rheometry. The relationship of the blends' viscosity with their composition, shear stress, shear rate, and temperature has been investigated. Power law index and activation energy of PLA, BionolleRTM #3000 and their blends have been calculated. The experimental and theoretical data can let us understand the processability of PLA/BionolleRTM #3000 blends. A scanning electron microscope (SEM) was used to investigate the morphological structure of the PLA/BionolleRTM #3000 blends. Micrographs of the samples made from different methods (blown film, extrudate and compression molding sheet) were taken; their differences in morphology were compared. For comparison, the micrographs of blend PLA/BionolleRTM #6000 was also studied. The

  3. Potential of a newly developed high-speed near-infrared (NIR) camera (Compovision) in polymer industrial analyses: monitoring crystallinity and crystal evolution of polylactic acid (PLA) and concentration of PLA in PLA/Poly-(R)-3-hydroxybutyrate (PHB) blends.

    PubMed

    Ishikawa, Daitaro; Nishii, Takashi; Mizuno, Fumiaki; Sato, Harumi; Kazarian, Sergei G; Ozaki, Yukihiro

    2013-12-01

    This study was carried out to evaluate a new high-speed hyperspectral near-infrared (NIR) camera named Compovision. Quantitative analyses of the crystallinity and crystal evolution of biodegradable polymer, polylactic acid (PLA), and its concentration in PLA/poly-(R)-3-hydroxybutyrate (PHB) blends were investigated using near-infrared (NIR) imaging. This NIR camera can measure two-dimensional NIR spectral data in the 1000-2350 nm region obtaining images with wide field of view of 150 × 250 mm(2) (approximately 100  000 pixels) at high speeds (in less than 5 s). PLA with differing crystallinities between 0 and 50% blended samples with PHB in ratios of 80/20, 60/40, 40/60, 20/80, and pure films of 100% PLA and PHB were prepared. Compovision was used to collect respective NIR spectra in the 1000-2350 nm region and investigate the crystallinity of PLA and its concentration in the blends. The partial least squares (PLS) regression models for the crystallinity of PLA were developed using absorbance, second derivative, and standard normal variate (SNV) spectra from the most informative region of the spectra, between 1600 and 2000 nm. The predicted results of PLS models achieved using the absorbance and second derivative spectra were fairly good with a root mean square error (RMSE) of less than 6.1% and a determination of coefficient (R(2)) of more than 0.88 for PLS factor 1. The results obtained using the SNV spectra yielded the best prediction with the smallest RMSE of 2.93% and the highest R(2) of 0.976. Moreover, PLS models developed for estimating the concentration of PLA in the blend polymers using SNV spectra gave good predicted results where the RMSE was 4.94% and R(2) was 0.98. The SNV-based models provided the best-predicted results, since it can reduce the effects of the spectral changes induced by the inhomogeneity and the thickness of the samples. Wide area crystal evolution of PLA on a plate where a temperature slope of 70-105 °C had occurred was also

  4. Photothermal and morphological characterization of PLA/PCL polymer blends

    NASA Astrophysics Data System (ADS)

    Correa-Pacheco, Z. N.; Jiménez-Pérez, J. L.; Sabino, M. A.; Cruz-Orea, A.; Loaiza, M.

    2015-09-01

    Nowadays, some synthetic polymers have been replaced by biodegradable polymers in order to avoid environmental contamination. Among these biodegradables polymers, aliphatic polyesters such as polylactic acid (PLA) and polycaprolactone (PCL) have been widely used. In the present study, solvent-casting films of PLA, PCL and polymer blends with and without compatibilizer (PLA grafted with maleic anhydride) were prepared. The thermal diffusivity ( α) of each sample was obtained by using the open photoacoustic cell technique. Morphology and thermal properties were determined by using scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry (DSC), respectively. The blends showed lower thermal diffusivity compared to pure polymers. However, when the compatibilizer was used, the highest value of thermal diffusivity was obtained. Also, cold crystallization with the highest value of enthalpy of fusion was observed for the compatibilized sample, which was revealed by DSC. To our knowledge, this is the first time that the thermal diffusivity of these biodegradable polymer blends is reported.

  5. Fabrication and characterization of a foamed polylactic acid (PLA)/ thermoplastic polyurethane (TPU) shape memory polymer (SMP) blend for biomedical and clinical applications

    NASA Astrophysics Data System (ADS)

    Song, Janice J.; Srivastava, Ijya; Kowalski, Jennifer; Naguib, Hani E.

    2014-03-01

    Shape memory polymers (SMP) are a class of stimuli-responsive materials that are able to respond to external stimulus such as heat by altering their shape. Bio-compatible SMPs have a number of advantages over static materials and are being studied extensively for biomedical and clinical applications (such as tissue stents and scaffolds). A previous study has demonstrated that the bio-compatible polymer blend of polylactic acid (PLA)/ thermoplastic polyurethane (TPU) (50/50 and 70/30) exhibit good shape memory properties. In this study, the mechanical and thermo-mechanical (shape memory) properties of TPU/PLA SMP blends were characterized; the compositions studied were 80/20, 65/35, and 50/50 TPU/PLA. In addition, porous TPU/PLA SMP blends were fabricated with a gas-foaming technique; and the morphology of the porous structure of these SMPs foams were characterized with scanning electron microscopy (SEM). The TPU/PLA bio-compatible SMP blend was fabricated with melt-blending and compression molding. The glass transition temperature (Tg) of the SMP blends was determined with a differential scanning calorimeter (DSC). The mechanical properties studied were the stress-strain behavior, tensile strength, and elastic modulus; and the thermomechanical (or shape memory) properties studied were the shape fixity rate (Rf), shape recovery rate (Rr), response time, and the effect of recovery temperature on Rr. The porous 80/20 PLA/TPU SMP blend was found to have the highest tensile strength, toughness and percentage extension, as well as the lowest density and uniform pore structure in the micron and submicron scale. The porous 80/20 TPU/PLA SMP blend may be further developed for specific biomedical and clinical applications where a combination of tensile strength, toughness, and low density are required.

  6. Preparation of hydrophilic poly(lactic acid) tissue engineering scaffold via (PLA)-(PLA-b-PEG)-(PEG) solution casting and thermal-induced surface structural transformation.

    PubMed

    Zhu, Xiaomin; Zhong, Tian; Huang, Ran; Wan, Ajun

    2015-01-01

    Porous poly(lactic acid) (PLA) tissue engineering scaffolds with a hydrophilic surface assembled by polyethylene glycol aggregations were prepared by the solvent casting/particulate leaching method from (PLA)-(PLA-b-PEG)-(PEG) blend solution, where the PLA-b-PEG block polymer serves as an amphiphilic glue between two phases. A thermal recrystallization process was inserted before leaching to induce a phase separation, which subsequently squeezes out PEG to form a hydrophilic shell. Characterizations of XRD and DSC indicated the composition and mixing states of materials. The water contact angle test qualitatively presented the excellent hydrophilicity compared to the pure PLA or PLA-PEG simple blend scaffold. The scanning electron microscope results confirmed the formation of porous structure of [Formula: see text] pore size, with an observable phase separation on the surface. The scaffold was degraded in PBS at [Formula: see text], and the degradation exhibits a three-stage behavior, which evidenced the amphiphilically glued phase separations.

  7. Effect of an acid filler on hydrolysis and biodegradation of poly-lactic acid (PLA)

    NASA Astrophysics Data System (ADS)

    Iozzino, Valentina; Speranza, Vito; Pantani, Roberto

    2015-12-01

    The use of biodegradable polymers is certainly an excellent strategy to solve many of the problems related to the disposal of the traditional polymers, whose accumulation in the environment is harmful and damaging. In order to optimize the use of biodegradable polymers, it is very important to understand and control the transformation processes, the structures and the morphologies resulting from the process conditions used to produce the articles and, not least, the biodegradation. The latter is strictly dependent on the just mentioned variables. The poly-lactic acid, PLA, is a biodegradable polymer. Many studies have been carried out on the degradation process of this polymer. In the course of this work we performed degradation tests on the PLA, with a specific D-isomer content, having amorphous structure, and in particular of biodegradation and hydrolysis. An acid chemical, fumaric acid, was added to PLA with the objective of controlling the rate of hydrolysis and of biodegradation. The hydrolysis process was followed, as function of time, by means of different techniques: pH variation, variation of weight of samples and variation of crystallinity degree and glass transition temperature using DSC analysis. The samples were also analyzed in terms of biodegradability by means of a homemade respirometer apparatus, in controlled composting conditions.

  8. Antibacterial poly(lactic acid) (PLA) films grafting electrospun PLA/Ally isothioscyanate (AITC) fibers for food packaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) fibers of submicron sizes encapsulating allyl isothiocyanate (AITC) (PfA) were made and electrospun onto the surfaces of PLA films (PfA-g-film). SEM examination confirmed that the fibers were grafted to the PLA film after the (PfA-g-film) underwent air blowing and water washi...

  9. Polylactic acid (PLA) controlled delivery carriers for biomedical applications.

    PubMed

    Tyler, Betty; Gullotti, David; Mangraviti, Antonella; Utsuki, Tadanobu; Brem, Henry

    2016-12-15

    Polylactic acid (PLA) and its copolymers have a long history of safety in humans and an extensive range of applications. PLA is biocompatible, biodegradable by hydrolysis and enzymatic activity, has a large range of mechanical and physical properties that can be engineered appropriately to suit multiple applications, and has low immunogenicity. Formulations containing PLA have also been Food and Drug Administration (FDA)-approved for multiple applications making PLA suitable for expedited clinical translatability. These biomaterials can be fashioned into sutures, scaffolds, cell carriers, drug delivery systems, and a myriad of fabrications. PLA has been the focus of a multitude of preclinical and clinical testing. Three-dimensional printing has expanded the possibilities of biomedical engineering and has enabled the fabrication of a myriad of platforms for an extensive variety of applications. PLA has been widely used as temporary extracellular matrices in tissue engineering. At the other end of the spectrum, PLA's application as drug-loaded nanoparticle drug carriers, such as liposomes, polymeric nanoparticles, dendrimers, and micelles, can encapsulate otherwise toxic hydrophobic anti-tumor drugs and evade systemic toxicities. The clinical translation of these technologies from preclinical experimental settings is an ever-evolving field with incremental advancements. In this review, some of the biomedical applications of PLA and its copolymers are highlighted and briefly summarized.

  10. Study of the free volume fraction in polylactic acid (PLA) by thermal analysis

    NASA Astrophysics Data System (ADS)

    Abdallah, A.; Benrekaa, N.

    2015-10-01

    The poly (lactic acid) or polylactide (PLA) is a biodegradable polymer with high modulus, strength and thermoplastic properties. In this work, the evolution of various properties of PLA is studied, such as glass transition temperature, mechanical modules and elongation percentage with the aim of investigating the free volume fraction. To do so, two thermal techniques have been used: the dynamic mechanical analysis (DMA) and dilatometry. The results obtained by these techniques are combined to go back to the structural properties of the studied material.

  11. Synthesis and characterization of L-lactide and polylactic acid (PLA) from L-lactic acid for biomedical applications

    NASA Astrophysics Data System (ADS)

    Rahmayetty, Sukirno, Prasetya, Bambang; Gozan, Misri

    2017-02-01

    Lactide is the monomer for the polymer polylactic acid (PLA) from lactic acid through polycondensation and depolymerization process. The properties of PLA strongly depend on the quality of the lactide monomer from which it is synthesized. Optical purity of lactide produced in depolymerization process confirmed to be L-lactide. The highest yield of crude lactide was 38.5% at temperature 210 °C with average molecular weight (Mn) of oligomer was 2389. Ring opening polymerization of lactide using Candida rugosa lipase as biocatalyst to PLLA synthesis has been achieved to generate useful biomedical materials free from heavy metal.

  12. Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

    PubMed

    Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

    2016-02-10

    Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

  13. Biodegradable packaging materials conception based on starch and polylactic acid (PLA) reinforced with cellulose.

    PubMed

    Masmoudi, Fatma; Bessadok, Atef; Dammak, Mohamed; Jaziri, Mohamed; Ammar, Emna

    2016-10-01

    The plastic materials used for packaging are increasing leading to a considerable amount of undegradable solid wastes. This work deals with the reduction of conventional plastics waste and the natural resources preservation by using cellulosic polymers from renewable resources (alfa and luffa). Plasticized starch films syntheses were achieved at a laboratory scale. These natural films showed some very attractive mechanical properties at relatively low plasticizers levels (12 to 17 % by weight). Furthermore, mixtures including polylactic acid polymer (PLA) and cellulose fibers extracted from alfa and luffa were investigated by melt extrusion technique. When used at a rate of 10 %, these fibers improved the mixture mechanical properties. Both developed materials were biodegradable, but the plasticized starch exhibited a faster biodegradation kinetic compared to the PLA/cellulose fibers. These new materials would contribute to a sustainable development and a waste reduction.

  14. Improve the Strength of PLA/HA Composite Through the Use of Surface Initiated Polymerization and Phosphonic Acid Coupling Agent

    PubMed Central

    Wang, Tongxin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Ting, Andy Hai; Dong, Quanxiao; Yang, Mingshu; Mitchell, James W.

    2011-01-01

    Bioresorbable composite made from degradable polymers, e.g., polylactide (PLA), and bioactive calcium phosphates, e.g., hydroxyapatite (HA), are clinically desirable for bone fixation, repair and tissue engineering because they do not need to be removed by surgery after the bone heals. However, preparation of PLA/HA composite from non-modified HA usually results in mechanical strength reductions due to a weak interface between PLA and HA. In this study, a calcium-phosphate/phosphonate hybrid shell was developed to introduce a greater amount of reactive hydroxyl groups onto the HA particles. Then, PLA was successfully grafted on HA by surface-initiated polymerization through the non-ionic surface hydroxyl groups. Thermogravimetric analysis indiated that the amount of grafted PLA on HA can be up to 7 %, which is about 50 % greater than that from the literature. PLA grafted HA shows significantly different pH dependent ζ-potential and particle size profiles from those of uncoated HA. By combining the phosphonic acid coupling agent and surface initiated polymerization, PLA could directly link to HA through covalent bond so that the interfacial interaction in the PLA/HA composite can be significantly improved. The diametral tensile strength of PLA/HA composite prepared from PLA-grafted HA was found to be over twice that of the composite prepared from the non-modified HA. Moreover, the tensile strength of the improved composite was 23 % higher than that of PLA alone. By varying additional variables, this approach has the potential to produce bioresorbable composites with improved mechanical properties that are in the range of natural bones, and can have wide applications for bone fixation and repair in load-bearing areas. PMID:22399838

  15. Investigation of Ultrasonics as a tool for energy efficient recycling of Lactic acid from postconsumer PLA products

    NASA Astrophysics Data System (ADS)

    Srinivasan, Gowrishankar

    The growing use of "ecofriendly," biodegradable polymers have created a need for a suitable recycling technique because, unlike petroleum derived plastics, their properties deteriorate during conventional recycling. These new techniques must be cost efficient and yield material properties same as virgin polymer. This research investigates the effectiveness of high-power ultrasonics as an efficient technique to recover lactic acid from postconsumer polylactic acid (PLA) products. Polylactic acid is a commercially available bioplastic derived from corn starch and/or sugar cane that is biorenewable and compostable (biodegradable). The various ongoing researches to recover lactic acid from PLA employ a common platform of high temperature, high pressure (HTHP) to effect polymer hydrolysis. The energy intensiveness of these HTHP processes prompted this work to investigate ultrasonics as an low energy alternative process to cause PLA depolymerization. The energy consumption and the time required for depolymerization were utilized as the metrics to quantify and compare depolymerization enhanced by ultrasonics with hot-bath technique. The coupled effect of catalysts concentration and different solvents, along with ultrasonic were studied based on preliminary trial results. In addition, the correlation between the rates of de-polymerization was analyzed for ultrasonic amplitude, treatment time, and catalyst concentration and types. The results indicate that depolymerization of PLA was largely effected by heating caused by ultrasonic-induced cavitations. Other effects of ultrasonics, namely cavitations and acoustic streaming, were shown to have minimal effects in enhancing depolymerization. In fact, thermal energy predominately affected the reaction kinetics; the heat introduced by conventional method (i.e., electrical heaters) was more efficient than ultrasonic heating in terms of energy (for depolymerization) per unit mass of PLA and depolymerizing time. The degree of

  16. Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodegradable polylactic acid (PLA) polymer was evaluated for its application as a material for antimicrobial food packaging. PLA films were incorporated with nisin to provide slow release of the encapsulated antimicrobial for control of foodborne pathogens. Antimicrobial activity of PLA/nisin films...

  17. Polymer blend of PLA/PHBV based bionanocomposites reinforced with nanocrystalline cellulose for potential application as packaging material.

    PubMed

    Dasan, Y K; Bhat, A H; Ahmad, Faiz

    2017-02-10

    The current research discusses the development of poly (lactic acid) (PLA) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced nanocrystalline cellulose bionanocomposites. The nanocrystalline cellulose was derived from waste oil palm empty fruit bunch fiber by acid hydrolysis process. The resulting nanocrystalline cellulose suspension was then surface functionalized by TEMPO-mediated oxidation and solvent exchange process. Furthermore, the PLA/PHBV/nanocrystalline cellulose bionanocomposites were produced by solvent casting method. The effect of the addition of nanocrystalline cellulose on structural, morphology, mechanical and barrier properties of bionanocomposites was investigated. The results revealed that the developed bionanocomposites showed improved mechanical properties and decrease in oxygen permeability rate. Therefore, the developed bio-based composite incorporated with an optimal composition of nanocrystalline cellulose exhibits properties as compared to the polymer blend.

  18. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding.

    PubMed

    Mi, Hao-Yang; Salick, Max R; Jing, Xin; Jacques, Brianna R; Crone, Wendy C; Peng, Xiang-Fang; Turng, Lih-Sheng

    2013-12-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold's microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications.

  19. Characterization of thermoplastic polyurethane/polylactic acid (TPU/PLA) tissue engineering scaffolds fabricated by microcellular injection molding

    PubMed Central

    Mi, Hao-Yang; Salick, Max R.; Jing, Xin; Jacques, Brianna R.; Crone, Wendy C.; Peng, Xiang-Fang; Turng, Lih-Sheng

    2015-01-01

    Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. PLA has rigid mechanical properties while TPU possesses flexible mechanical properties. Blended TPU/PLA tissue engineering scaffolds at different ratios for tunable properties were fabricated via twin screw extrusion and microcellular injection molding techniques for the first time. Multiple test methods were used to characterize these materials. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of the two components in the blends; differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between the TPU and PLA. Scanning electron microscopy (SEM) images verified that, at the composition ratios studied, PLA was dispersed as spheres or islands inside the TPU matrix and that this phase morphology further influenced the scaffold’s microstructure and surface roughness. The blends exhibited a large range of mechanical properties that covered several human tissue requirements. 3T3 fibroblast cell culture showed that the scaffolds supported cell proliferation and migration properly. Most importantly, this study demonstrated the feasibility of mass producing biocompatible PLA/TPU scaffolds with tunable microstructures, surface roughnesses, and mechanical properties that have the potential to be used as artificial scaffolds in multiple tissue engineering applications. PMID:24094186

  20. Cytocompatibility and Mechanical Properties of Short Phosphate Glass Fibre Reinforced Polylactic Acid (PLA) Composites: Effect of Coupling Agent Mediated Interface

    PubMed Central

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew; Walker, Gavin; Scotchford, Colin

    2012-01-01

    In this study three chemical agents Amino-propyl-triethoxy-silane (APS), sorbitol ended PLA oligomer (SPLA) and Hexamethylene diisocyanate (HDI) were identified to be used as coupling agents to react with the phosphate glass fibre (PGF) reinforcement and the polylactic acid (PLA) polymer matrix of the composite. Composites were prepared with short chopped strand fibres (l = 20 mm, ϕ = 20 µm) in a random arrangement within PLA matrix. Improved, initial composite flexural strength (~20 MPa) was observed for APS treated fibres, which was suggested to be due to enhanced bonding between the fibres and polymer matrix. Both APS and HDI treated fibres were suggested to be covalently linked with the PLA matrix. The hydrophobicity induced by these coupling agents (HDI, APS) helped to resist hydrolysis of the interface and thus retained their mechanical properties for an extended period of time as compared to non-treated control. Approximately 70% of initial strength and 65% of initial modulus was retained by HDI treated fibre composites in contrast to the control, where only ~50% of strength and modulus was retained after 28 days of immersion in PBS at 37 °C. All coupling agent treated and control composites demonstrated good cytocompatibility which was comparable to the tissue culture polystyrene (TCP) control, supporting the use of these materials as coupling agent’s within medical implant devices. PMID:24955744

  1. Coating of poly(p-xylylene) by PLA-PEO-PLA triblock copolymers with excellent polymer-polymer adhesion for stent applications.

    PubMed

    Hanefeld, Phillip; Westedt, Ullrich; Wombacher, Ralf; Kissel, Thomas; Schaper, Andreas; Wendorff, Joachim H; Greiner, Andreas

    2006-07-01

    Poly(p-xylylene) (PPX) was deposited by chemical vapor deposition (CVD) on stainless steel substrates. These PPX films were coated by solution casting of poly(lactide)-poly(ethylene oxide)-poly(lactide) triblock copolymers (PLA-PEO-PLA) loaded with 14C-labeled paclitaxel. Adhesion of PLA-PEO-PLA on PPX substrate coatings was measured using the blister test method. Excellent adhesion of the block copolymers on PPX substrates was found. Stress behavior and film integrity of PLA-PEO-PLA was compared to pure PLA on unexpanded and expanded stent bodies and was found to be superior for the block copolymers. The release of paclitaxel from the biodegradable coatings was studied under physiological conditions using the scintillation counter method. Burst release of paclitaxel was observed from PLA-PEO-PLA layers regardless of composition, but an increase in paclitaxel loading was observed with increasing content of PEO.

  2. Additive Manufacturing and Characterization of Polylactic Acid (PLA) Composites Containing Metal Reinforcements

    NASA Technical Reports Server (NTRS)

    Kuentz, Lily; Salem, Anton; Singh, M.; Halbig, M. C.; Salem, J. A.

    2016-01-01

    Additive manufacturing of polymeric systems using 3D printing has become quite popular recently due to rapid growth and availability of low cost and open source 3D printers. Two widely used 3D printing filaments are based on polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) systems. PLA is much more environmentally friendly in comparison to ABS since it is made from renewable resources such as corn, sugarcane, and other starches as precursors. Recently, polylactic acid-based metal powder containing composite filaments have emerged which could be utilized for multifunctional applications. The composite filaments have higher density than pure PLA, and the majority of the materials volume is made up of polylactic acid. In order to utilize functionalities of composite filaments, printing behavior and properties of 3-D printed composites need to be characterized and compared with the pure PLA materials. In this study, pure PLA and composite specimens with different metallic reinforcements (Copper, Bronze, Tungsten, Iron, etc) were 3D printed at various layer heights and resulting microstructures and properties were characterized. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) behavior of filaments with different reinforcements were studied. The microscopy results show an increase in porosity between 3-D printed regular PLA and the metal composite PLA samples, which could produce weaker mechanical properties in the metal composite materials. Tensile strength and fracture toughness behavior of specimens as a function of print layer height will be presented.

  3. Improved thermal stability of polylactic acid (PLA) composite film via PLA-β-cyclodextrin-inclusion complex systems.

    PubMed

    Byun, Youngjae; Rodriguez, Katia; Han, Jung H; Kim, Young Teck

    2015-11-01

    The effects of the incorporation of PLA-β-cyclodextrin-inclusion complex (IC) and β-cyclodextrin (β-CD) on biopolyester PLA films were investigated. Thermal stability, surface morphology, barrier, and mechanical properties of the films were measured at varying IC (1, 3, 5, and 7%) and β-CD (1 and 5%) concentrations. The PLA-IC-composite films (IC-PLA-CFs) showed uniform morphological structure, while samples containing β-CD (β-CD-PLA-CFs) showed high agglomeration of β-CD due to poor interfacial interaction between β-CD and PLA moieties. According to the thermal property analysis, the 5% IC-PLA-CFs showed 6.6 times lower dimensional changes (6.5%) at the temperature range of 20-80°C than that of pure PLA film (43.0%). The increase of IC or β-CD content in the PLA-composite films shifted the glass transition and crystallization temperature to higher temperature regions. The crystallinity of both composite films improved by increasing IC or β-CD content. Both composite films had higher oxygen and water vapor permeability as IC or β-CD content increased in comparison to pure PLA film. All the composite films had less flexibility and lower tensile strength than the pure PLA film. In conclusion, this study shows that the IC technique is valuable to improve the thermal expansion stability of PLA-based films.

  4. Influence of Filler on the Mechanical Properties and Kinetic Crystallization Behavior of Polylactic Acid (PLA)

    NASA Astrophysics Data System (ADS)

    Mitsuta, Ryo; Inoue, Ryohei; Hara, Ryosuke; Sato, Sadao

    The kinetic crystallization behavior of PLA (polylactic acid) and PLA/MMT nanocomposites containing 3 wt% montmorillonite (MMT) was examined in order to develop a new technique for obtaining the relative crystallization degree of a material from the spherulite occupation area based on images obtained using a charge-coupled device (CCD) camera. In addition, the relative crystallization degree is discussed in terms of the Ozawa theory. The effect of MMT filler on the mechanical properties of PLA/MMT nanocomposites, the number of spherulites generated in the nanocomposites, and the linear growth rate of these spherulites were also examined experimentally. The relative crystallization curves obtained by CCD and by DSC measurement were found to be approximately the same. Moreover, it was found that the Ozawa theory could be applied not only to PLA but also to PLA/MMT nanocomposites. In these nanocomposites, the number of spherulites decreased and the linear growth rate slightly increased ; moreover, the rate of crystallization also increased. The tensile and flexural modulus of the PLA/MMT nanocomposites containing 3 wt% MMT were 5.2-14.3% greater than those of PLA, and annealing resulted in a further increase of about 4.0-20.7%. However, the Izod impact value decreased due to the increase in rigidity caused by annealing and the addition of filler.

  5. Thermal and mechanical properties of polylactic acid (PLA) and bagasse carboxymethyl cellulose (CMCB) composite by adding isosorbide diesters

    NASA Astrophysics Data System (ADS)

    Kamthai, Suthaphat; Magaraphan, Rathanawan

    2015-05-01

    An isosorbide diesters is one of isororbide types used as a plasticizer. The influence of this plasticizer on thermal and mechanical properties of polylactic acid and bagasse carboxymethyl cellulose (PLA/CMCB) composites was studied. PLA was blended with CMCB at 1%wt using various contents of isosorbide diesters (5, 10, 15 and 20%wt of PLA). The differential scanning calorimetric (DSC) and thermogravimetric (TGA) analyses indicated that the increment of isosorbide diesters concentration resulted in decreasing glass transition, melting and decomposition temperatures, as well as the reduction of storage modulus of PLA/CMCB composites. Moreover, the elongation of PLA/CMCB composites was significantly improved with increasing plasticizer content.

  6. Biodegradable PLA (polylactic acid) hinged trays keep quality of fresh-cut and cooked spinach.

    PubMed

    Botondi, Rinaldo; Bartoloni, Serena; Baccelloni, Simone; Mencarelli, Fabio

    2015-09-01

    This work examines the effects of packaging using two different polymeric trays with hinged lids, polyethylene terephthalate (PET) and polylactic acid (PLA), on fresh-cut and cooked spinach (Spinacia oleracea). Samples were stored in a cold room for 16 days at 4 °C. Chemical (total pigments, total polyphenols, ascorbic acid, antioxidant activity), physical (water activity), technological (colour evaluation), sensorial (aroma, visual appearance and water accumulation) and microbial (total aerobic mesophilic and psychrotrophic counts) parameters were tested. Both polymeric trays maintained the overall quality of fresh spinach for 6 days but spinach stored in PLA trays maintained its flavour longer. A significant increase in total polyphenols, antiradical activity, total carotenoids as well as a decrease in ascorbic acid in fresh spinach was observed in the first 3 days of storage in both samples. Unfortunately, the PLA package accumulated condensed water. The total microbial load of fresh-cut spinach reached about 6.3-7.3 log CFU g(-1) within 8 days. Cooked spinach packed in PLA and PET polymeric hinged trays showed the same behaviour as fresh spinach in terms of quality and shelf life. In conclusion, PLA plastic hinged trays can be used for packaging fresh-cut and cooked cut spinach, but the problem of condensed water must be solved.

  7. Polylactic acid (PLA)/Silver-NP/VitaminE bionanocomposite electrospun nanofibers with antibacterial and antioxidant activity

    NASA Astrophysics Data System (ADS)

    Munteanu, Bogdanel Silvestru; Aytac, Zeynep; Pricope, Gina M.; Uyar, Tamer; Vasile, Cornelia

    2014-10-01

    The antibacterial property of silver nanoparticles (Ag-NPs) and the antioxidant activity of Vitamin E have been combined by incorporation of these two active components within polylactic acid (PLA) nanofibers via electrospinning (PLA/Ag-NP/VitaminE nanofibers). The morphological and structural characterizations of PLA/Ag-NP/VitaminE nanofibers were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy and X-ray diffraction. The average fiber diameter was 140 ± 60 nm, and the size of the Ag-NP was 2.7 ± 1.5 nm. PLA/Ag-NP/VitaminE nanofibers inhibited growth of Escherichia coli, Listeria monocytogenes and Salmonella typhymurium up to 100 %. The amount of released Ag ions from the nanofibers immersed in aqueous solution was determined by Inductively Coupled Plasma Mass Spectrometry, and it has been observed that the release of Ag ions was kept approximately constant after 10 days of immersion. The antioxidant activity of PLA/Ag-NP/VitaminE nanofibers was evaluated according to DPPH (2,2-diphenyl-1-picrylhydrazyl) method and determined as 94 %. The results of the tests on fresh apple and apple juice indicated that the PLA/Ag/VitaminE nanofiber membrane actively reduced the polyphenol oxidase activity. The multifunctional electrospun PLA nanofibers incorporating Ag-NP and Vitamin E may be quite applicable in food packaging due to the extremely large surface area of nanofibers along with antibacterial and antioxidant activities. These materials could find application in food industry as a potential preservative packaging for fruits and juices.

  8. Tacticity control in the synthesis of poly(lactic acid) polymer stars with dipentaerythritol cores.

    PubMed

    Shaver, Michael P; Cameron, Donald J A

    2010-12-13

    The synthesis of a family of polymer stars with arms of varied tacticities is discussed. The effect of polymer tacticity on the physical properties of these polymer stars is presented. Dipentaerythritol cores support six poly(lactic acid) (PLA) arms. Lewis acidic tin and aluminum catalysts control the polymerization to afford polymer stars of variable tacticity. The analysis of these polymers by NMR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and differential scanning calorimetry reveals the effects of tacticity control on the physical properties of the polymer stars. Preliminary decomposition studies suggest that the biodegradation profile of a polymer star may also be tuned by stereochemical control. This is the first systematic altering of tacticity in PLA polymer stars, showing that polymer tacticity can have a great impact on star properties.

  9. Biodegradable polylactic acid polymer with nisin for use in antimicrobial food packaging.

    PubMed

    Jin, T; Zhang, H

    2008-04-01

    Biodegradable polylactic acid (PLA) polymer was evaluated for its application as a material for antimicrobial food packaging. PLA films were incorporated with nisin to for control of foodborne pathogens. Antimicrobial activity of PLA/nisin films against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Enteritidis were evaluated in culture media and liquid foods (orange juice and liquid egg white). Scanned electron micrograph and confocal laser microscopy revealed that nisin particles were evenly distributed in PLA polymer matrix on the surface and inside of the PLA/nisin films. PLA/nisin significantly inhibited growth of L. monocytogenes in culture medium and liquid egg white. The greatest inhibition occurred at 24 h when the cell counts of L. monocytogenes in the PLA/nisin samples were 4.5 log CFU/mL less than the controls. PLA/nisin reduced the cell population of E. coli O157:H7 in orange juice from 7.5 to 3.5 log at 72 h whereas the control remained at about 6 log CFU/mL. PLA/nisin treatment resulted in a 2 log reduction of S. Enteritidis in liquid egg white at 24 degrees C. After 21 d at 4 degrees C the S. Enteritidis population from PLA/nisin treated liquid egg white (3.5 log CFU/mL) was significantly less than the control (6.8 log CFU/mL). E. coli O157:H7 in orange juice was more sensitive to PLA/nisin treatments than in culture medium. The results of this research demonstrated the retention of nisin activity when incorporated into the PLA polymer and its antimicrobial effectiveness against foodborne pathogens. The combination of a biopolymer and natural bacteriocin has potential for use in antimicrobial food packaging.

  10. Modification of cellulose nanocrystals with lactic acid for direct melt blending with PLA

    NASA Astrophysics Data System (ADS)

    Spinella, Stephen; Re, Giada Lo; Liu, Bo; Dorgan, John; Habibi, Youssef; Raquez, Jean-Marie; Dubois, Philippe; Gross, Richard A.

    2015-05-01

    Polylactide (PLA) is a commercially produced bio-based thermoplastic with unique properties such as high strength, biocompatibility and biodegradability. However, the low heat deflection temperature (HDT) of PLA significantly impedes its industrial implementation for high-performance applications, requiring the design of PLA-based nanocomposites. Cellulose nanocrystals (CNCs) are derived from cellulose which is highly abundant in nature, non-toxic, biodegradable, and has a low density. CNCs possess many attractive features for use in nano-composites. The main problem of adding hydrophilic CNCs into hydrophobic matrixes is their lack of affinity, leading to phase separation and a decrease in mechanical properties. A one-step method based on both Fischer esterification and acid hydrolysis was used in this work to obtain functionalized and ready-to-use CNCs, with the aim to improve the filler dispersion into the polymeric matrix. The study assesses the reinforcing effect of CNCs on PLA-based materials. CNCs functionalized with acetate (AA-CNCs), lactic acid (LA-CNCs) and unfunctionalized CNCs were synthesized and blends of PLA and these CNCs were prepared by direct melt blending. The corresponding thermomechanical properties were investigated by DMTA. Blends with LA-CNCs possessed the highest storage modulus. Based on these results, blends with up to 20 % LA-CNCs were prepared by direct melt blending and an increase of up to 20°C in the HDT resulted. A decrease in oxygen permeability also resulted from increasing the nano-filler content. This increase in materials properties can potentially expand the applications of PLA based materials.

  11. SKELETAL MUSCLE GROUP VIA PHOSPHOLIPASE A2 (iPLA2β): EXPRESSION AND ROLE IN FATTY ACID OXIDATION†

    PubMed Central

    Carper, Michael J.; Zhang, Sheng; Turk, John; Ramanadham, Sasanka

    2009-01-01

    Among the phospholipases A2 (PLA2s) are the Group VI Ca2+-independent PLA2s (iPLA2s) and expression of multiple transcripts of iPLA2 in skeletal muscle has been reported. In the present study, phospholipase activity and sequential ATP and calmodulin affinity column chromatography analyses reveal that skeletal muscle iPLA2 exhibits properties characteristic of the iPLA2β isoform. The phospholipase activity of iPLA2β has been demonstrated to participate in signal transduction, cell proliferation, and apoptosis. We also report here that skeletal muscle from iPLA2β-null mice, relative to wild type muscle, exhibits a reduced capacity to oxidize palmitate but not palmitoyl-CoA or acetyl-CoA in the absence of changes in fatty acid transporters CD36 and CPT1 or β-hydroxyacyl-CoA dehydrogenase activity. Recently, purified iPLA2β was demonstrated to manifest a thioesterase activity which catalyzes hydrolysis of fatty acyl-CoAs. The liberated CoA-SH facilitates fatty acid transport into the mitochondria. In this regard, we find that fractions eluted from the ATP column and containing iPLA2β phospholipase activity also contained acyl-CoA thioesterase activity that was inhibited by the bromoenol lactone (BEL) suicide inhibitor of iPLA2β. We further find that acyl-CoA thioesterase activity in skeletal muscle preparations from iPLA2β-null mice is significantly reduced, relative to WT activity. These findings suggest that the absence of acyl-CoA thioesterase activity of iPLA2β can lead to reduced fatty acyl-CoA generation and impair fatty acid oxidation in iPLA2β-null mice. Our findings therefore reveal a novel function of iPLA2β, related not to its phospholipase activity but to its thioesterase activity, which contributes to optimal fatty acid oxidation in skeletal muscle. PMID:18937505

  12. Mechanical, thermal, and biodegradable properties of polylactic acid (PLA)/coir fibre biocomposites

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Ghataura, A.; Haroosh, H. J.

    2013-08-01

    Polylactic acid (PLA)/coir fibre biocomposites were fabricated using a compression moulding technique. The effects of fibre content (5-30 wt%) and fibre treatment on mechanical, thermal and biodegradable properties of biocomposites were holistically investigated via mechanical testing, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and soil burial method to understand the applicability of manufacturing eco-efficient and sustainable "green composites".

  13. Cold atmospheric plasma (CAP) surface nanomodified 3D printed polylactic acid (PLA) scaffolds for bone regeneration.

    PubMed

    Wang, Mian; Favi, Pelagie; Cheng, Xiaoqian; Golshan, Negar H; Ziemer, Katherine S; Keidar, Michael; Webster, Thomas J

    2016-12-01

    Three-dimensional (3D) printing is a new fabrication method for tissue engineering which can precisely control scaffold architecture at the micron-scale. However, scaffolds not only need 3D biocompatible structures that mimic the micron structure of natural tissues, they also require mimicking of the nano-scale extracellular matrix properties of the tissue they intend to replace. In order to achieve this, the objective of the present in vitro study was to use cold atmospheric plasma (CAP) as a quick and inexpensive way to modify the nano-scale roughness and chemical composition of a 3D printed scaffold surface. Water contact angles of a normal 3D printed poly-lactic-acid (PLA) scaffold dramatically dropped after CAP treatment from 70±2° to 24±2°. In addition, the nano-scale surface roughness (Rq) of the untreated 3D PLA scaffolds drastically increased (up to 250%) after 1, 3, and 5min of CAP treatment from 1.20nm to 10.50nm, 22.90nm, and 27.60nm, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed that the ratio of oxygen to carbon significantly increased after CAP treatment, which indicated that the CAP treatment of PLA not only changed nano-scale roughness but also chemistry. Both changes in hydrophilicity and nano-scale roughness demonstrated a very efficient plasma treatment, which in turn significantly promoted both osteoblast (bone forming cells) and mesenchymal stem cell attachment and proliferation. These promising results suggest that CAP surface modification may have potential applications for enhancing 3D printed PLA bone tissue engineering materials (and all 3D printed materials) in a quick and an inexpensive manner and, thus, should be further studied.

  14. Dual responsive polymeric nanoparticles prepared by direct functionalization of polylactic acid-based polymers via graft-from ring opening metathesis polymerization.

    PubMed

    Veccharelli, Kate M; Tong, Venus K; Young, Jennifer L; Yang, Jerry; Gianneschi, Nathan C

    2016-01-11

    Polylactic acid (PLA) has found widespread use in plastics and in biomedical applications due to its biodegradability into natural benign products. However, PLA-based materials remain limited in usefulness due to difficulty of incorporating functional groups into the polymer backbone. In this paper, we report a strategy for PLA functionalization that establishes the preparation of highly derivatized materials in which ring opening metathesis polymerization (ROMP) is employed as a graft-from polymerization technique utilizing a norbornene-modified handle incorporated into the PLA backbone. As a demonstration of this new synthetic methodology, a PLA-derived nanoparticle bearing imidazole units protected with a photolabile group was prepared. The morphology of this material could be controllably altered in response to exposure of UV light or acidic pH as a stimulus. We anticipate that this graft-from approach to derivatization of PLA could find broad use in the development of modified, biodegradable PLA-based materials.

  15. Electrospun membranes of poly(lactic acid) (PLA) used as scaffold in drug delivery of extract of Sedum dendroideum.

    PubMed

    Santos, Larissa G; Oliveira, Daniel C; Santos, Michele S L; Neves, Lia Mara G; de Gaspi, Fernanda O G; Mendonça, Fernanda A S; Esquisatto, Marcelo A M; Santos, Gláucia M T; d'Avila, M A; Mei, Lucia H Innocentini

    2013-07-01

    Biomaterials nanofibrous electrospun with biodegradable polymers have the advantage of the similarity to natural extracellular matrices, showing promising as scaffolds for application in tissue engineering. Sedum dendroideum is a phytotherapic drug that stands out for its healing properties and anti-inflammatory. This study presents the efficacy of PLA electrospun membranes used as support S. dendroideum extract releasing on excisional skin lesions of Wistar rats. The PLA porous membranes, which are nonwoven fibrous mats, were obtained by electrospinning using a conventional apparatus with a flat collector. The animals were randomly divided into nine groups: control (C), animals treated with electrospun membranes of PLA (M), animals treated with extract of S. dendroideum dissolved in saline (F), animals treated with membranes of PLA with 10% S. dendroideum (MF10), animals treated with membranes of PLA with 25% S. dendroideum (MF25). Tissue samples were taken after 2, 6 and 10 days after surgery and were subjected to structural analysis and morphology. The experimental observations showed the application of the phytotherapic incorporated in the membrane promoted a significant response regarding the number of inflammatory cells, percentage of mature collagen fibers and epithelium birrefringent in thickness excisional skin lesions in Wistar rats. It was also demonstrated that the application of the PLA membranes without the extract promoted similar responses tissues.

  16. An overview of the recent developments in polylactide (PLA) research.

    PubMed

    Madhavan Nampoothiri, K; Nair, Nimisha Rajendran; John, Rojan Pappy

    2010-11-01

    The concept of biodegradable plastics is of considerable interest with respect to solid waste accumulation. Greater efforts have been made in developing degradable biological materials without any environmental pollution to replace oil-based traditional plastics. Among numerous kinds of degradable polymers, polylactic acid sometimes called polylactide, an aliphatic polyester and biocompatible thermoplastic, is currently a most promising and popular material with the brightest development prospect and was considered as the 'green' eco friendly material. Biodegradable plastics like polyglycolic acid, polylactic acid, polycaprolactone, polyhydroxybutyrate, etc. are commercially available for controlled drug releases, implantable composites, bone fixation parts, packaging and paper coatings, sustained release systems for pesticides and fertilizers and compost bags etc. This review will provide information on current PLA market, brief account on recent developments in the synthesis of lactic acid (monomer of PLA) through biological route, PLA synthesis, unique material properties of PLA and modification of those by making copolymers and composites, PLA degradation and its wide spectrum applications.

  17. Polylactic Acid-Based Polymer Blends for Durable Applications

    NASA Astrophysics Data System (ADS)

    Finniss, Adam

    There has been considerable scientific interest in both research and commercial communities as of late in the area of biologically based or sourced plastics. As the consumption of petroleum rises and concerns about climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use PLA more widely, especially in durable applications. Unfortunately, PLA has several drawbacks that hinder more widespread usage of the material as a durable item: it has low ductility and impact strength in bulk applications, along with poor stability in the face of heat, humidity or liquid media. To combat these deficiencies, a number of techniques were investigated. Samples were annealed to create crystalline domains that would improve mechanical properties and reduce diffusion, blended with graphene to create barriers to diffusion throughout the material, or compounded with a polycarbonate (PC) polymer phase to protect the PLA phase and to enhance the mechanical properties of the blend. If a material containing biologically sourced components with good mechanical properties can be created, it would be desirable for durable uses such as electronics components or as an automotive grade resin. Crystallization experiments were carried out in a differential scanning calorimeter to determine the effects of heat treatment and additives on the rather slow crystallization kinetics of PLA polymer. It was determined that the blending in of the PC phase did not significantly alter the kinetics or mechanism of crystal growth. The addition of graphene to any PC/PLA formulation served as a nucleating agent which speeded up the crystallization kinetics markedly, in some cases by several orders of magnitude. Results obtained from these experiments were internally consistent

  18. Three-dimensional printing with polylactic acid (PLA) thermoplastic offers new opportunities for cryobiology.

    PubMed

    Tiersch, Terrence R; Monroe, William T

    2016-12-01

    Development of devices through design, prototyping, testing, and fabrication is especially necessary for enhancement of research and eventual application in cryobiology. The advent of 3-dimensional printing offers unique opportunities for this process, given that the materials involved are suitable for use in cryogenic temperatures. We report herein that 3-D printing with polylactic acid (PLA) thermoplastic is ideally suited for cryobiology device development. Devices that are designed and standardized in open-source fashion can be electronically distributed and created locally on increasingly affordable 3-D printers, and can accelerate cryobiology findings and improve reproducibility of results.

  19. Miscibility of poly(lactic acid) and poly(ethylene oxide) solvent polymer blends and nanofibers made by solution blow spinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The miscibility of blends of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) was studied in polymer solutions by dilute solution viscometry and in solution blow spun nanofibers by microscopy (SEM, TEM) and by thermal and spectral analysis. Three blends of PLA and PEO were solution blended in...

  20. Paclitaxel-loaded nanoparticles of star-shaped cholic acid-core PLA-TPGS copolymer for breast cancer treatment

    PubMed Central

    2013-01-01

    A system of novel nanoparticles of star-shaped cholic acid-core polylactide-d-α-tocopheryl polyethylene glycol 1000 succinate (CA-PLA-TPGS) block copolymer was developed for paclitaxel delivery for breast cancer treatment, which demonstrated superior in vitro and in vivo performance in comparison with paclitaxel-loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles and linear PLA-TPGS nanoparticles. The paclitaxel- or couramin 6-loaded nanoparticles were fabricated by a modified nanoprecipitation method and then characterized in terms of size, surface charge, surface morphology, drug encapsulation efficiency, and in vitro drug release. The CA-PLA-TPGS nanoparticles were found to be spherical in shape with an average size of around 120 nm. The nanoparticles were found to be stable, showing no change in the particle size and surface charge during 90-day storage of the aqueous solution. The release profiles of the paclitaxel-loaded nanoparticles exhibited typically biphasic release patterns. The results also showed that the CA-PLA-TPGS nanoparticles have higher antitumor efficacy than the PLA-TPGS nanoparticles and PLGA nanoparticles in vitro and in vivo. In conclusion, such nanoparticles of star-shaped cholic acid-core PLA-TPGS block copolymer could be considered as a potentially promising and effective strategy for breast cancer treatment. PMID:24134303

  1. Lignin poly(lactic acid) copolymers

    DOEpatents

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  2. Polymer-Nucleic Acid Interactions.

    PubMed

    Shen, Zhuang-Lin; Xia, Yi-Qi; Yang, Qiu-Song; Tian, Wen-de; Chen, Kang; Ma, Yu-Qiang

    2017-04-01

    Gene therapy is an important therapeutic strategy in the treatment of a wide range of genetic disorders. Polymers forming stable complexes with nucleic acids (NAs) are non-viral gene carriers. The self-assembly of polymers and nucleic acids is typically a complex process that involves many types of interaction at different scales. Electrostatic interaction, hydrophobic interaction, and hydrogen bonds are three important and prevalent interactions in the polymer/nucleic acid system. Electrostatic interactions and hydrogen bonds are the main driving forces for the condensation of nucleic acids, while hydrophobic interactions play a significant role in the cellular uptake and endosomal escape of polymer-nucleic acid complexes. To design high-efficiency polymer candidates for the DNA and siRNA delivery, it is necessary to have a detailed understanding of the interactions between them in solution. In this chapter, we survey the roles of the three important interactions between polymers and nucleic acids during the formation of polyplexes and summarize recent understandings of the linear polyelectrolyte-NA interactions and dendrimer-NA interactions. We also review recent progress optimizing the gene delivery system by tuning these interactions.

  3. Biodegradable blends of poly (lactic acid) (PLA) / polyhydroxybutrate (PHB) copolymer and its effects on rheological, thermal and mechanical properties

    NASA Astrophysics Data System (ADS)

    Sood, Nitin K.

    Poly (Lactic acid) is the most important plastic derived from the renewable resources. PLA based products have extensively been used in the medical industry. However, PLA has a few disadvantages such as inherent brittleness and low toughness despite a high modulus. A focus of this experiment was to study the improvement in toughness of PLA and to study the changes in thermal and rheological properties by blending PLA with a PHB copolymer. Where, PLA and PHB copolymer were melt blended using a twin screw Brabender extruder in the ratios of 100/0, 70/30, 50/50, 30/70, 0/100. Further, the blends were injection molded into tensile bar and impact bars for mechanical testing. Rheological properties were studied using a Galaxy capillary rheometer for melt viscosities and temperature dependence indicated a shear-thinning behavior along with power law model and consistency index. Blends were characterized to study the phase model using a differential scanning calorimetric (DSC), showed two separate phases. Mechanical properties were analyzed using a Tensile and Izod impact test indicating decrease in elastic modulus with increase in toughness and elongation as the PHB copolymer content was increased in the blend.

  4. Mechanical and moisture barrier properties of titanium dioxide nanoparticles and halloysite nanotubes reinforced polylactic acid (PLA)

    NASA Astrophysics Data System (ADS)

    Alberton, J.; Martelli, S. M.; Fakhouri, F. M.; Soldi, V.

    2014-08-01

    Polylactic acid (PLA) has been larger used in biomedical field due to its low toxicity and biodegradability. The aim of this study was to produce PLLA nanocomposites, by melt extrusion, containing Halloysite nanotubes (HNT) and/or titanium dioxide (TiO2) nanoparticles. Immediately after drying, PLLA was mechanically homogenized with the nanofillers and then melt blended using a single screw extruder (L/D = 30) at a speed of 110 rpm, with three heating zones in which the following temperatures were maintained: 150, 150 and 160°C (AX Plasticos model AX14 LD30). The film samples were obtained by compression molding in a press with a temperature profile of 235 ± 5°C for 2.5 min, after pressing, films were cooled up to room temperature. The mechanical tests were performed according to ASTM D882-09 and the water vapor permeability (WVP) was measured according to ASTM E-96, in triplicate. The tensile properties indicated that the modulus was improved with increased TiO2 content up to 1g/100g PLLA. The Young's modulus (YM) of the PLA was increased from 3047 MPa to 3222 MPa with the addition of 1g TiO2/100g PLLA. The tensile strength (TS) of films increases with the TiO2 content. In both cases, the YM and TS are achieved at the 1% content of TiO2 and is due to the reinforcing effect of nanoparticles. Pristine PLA showed a strain at break (SB) of 3.56%, while the SB of nanocomposites were significant lower, for instance the SB of composite containing 7.5 g HNT/100g PLLA was around 1.90 %. The WVP of samples was increased by increasing the nano filler content. It should be expected that an increase of nanofiller content would decrease the mass transfer of water molecules throughout the samples due to the increase in the way water molecules will have to cross to permeate the material. However, this was not observed. Therefore, this result can be explained considering the molecular structure of both fillers, which contain several hydroxyl groups in the surface, making the

  5. Drastic Attenuation of Pseudomonas aeruginosa Pathogenicity in a Holoxenic Mouse Experimental Model Induced by Subinhibitory Concentrations of Phenyllactic acid (PLA)

    PubMed Central

    Chifiriuc, Mariana–Carmen; Veronica, Lazar; Dracea, Olguta; Ditu, Lia-Mara; Smarandache, Diana; Bucur, Marcela; Larion, Cristina; Cernat, Ramona; Sasarman, Elena

    2007-01-01

    The discovery of communication systems regulating bacterial virulence has afforded a novel opportunity to control infectious bacteria without interfering with growth. In this paper we describe the effect of subinhibitory concentrations of phenyllactic acid (PLA) on the pathogenicity of Pseudomonas aeruginosa in mice. The animals were inoculated by oral (p.o.), intranasal (i.n.), intravenous (i.v.) and intraperitoneal (i.p.) routes with P. aeruginoasa wild and PLA-treated cultures. The mice were followed up during 16 days after infection and the body weight, mortality and morbidity rate were measured every day. The microbial charge was studied by viable cell counts in lungs, spleen, intestinal mucosa and blood. The mice batches infected with wild P. aeruginosa bacterial cultures exhibited high mortality rates (100 % after i.v. and i.p. route) and very high cell counts in blood, lungs, intestine and spleen. In contrast, the animal batches infected with PLA treated bacterial cultures exhibited good survival rates (0 % mortality) and the viable cell counts in the internal organs revealed with one exception the complete abolition of the invasive capacity of the tested strains. In this study, using a mouse infection model we show that D-3-phenyllactic acid (PLA) can act as a potent antagonist of Pseudomonas (P.) aeruginosa pathogenicity, without interfering with the bacterial growth, as demonstrated by the improvement of the survival rates as well as the clearance of bacterial strains from the body.

  6. Multifunctional PLA-PHB/cellulose nanocrystal films: processing, structural and thermal properties.

    PubMed

    Arrieta, M P; Fortunati, E; Dominici, F; Rayón, E; López, J; Kenny, J M

    2014-07-17

    Cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose by acid hydrolysis were added into poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends to improve the final properties of the multifunctional systems. CNC were also modified with a surfactant (CNCs) to increase the interfacial adhesion in the systems maintaining the thermal stability. Firstly, masterbatch pellets were obtained for each formulation to improve the dispersion of the cellulose structures in the PLA-PHB and then nanocomposite films were processed. The thermal stability as well as the morphological and structural properties of nanocomposites was investigated. While PHB increased the PLA crystallinity due to its nucleation effect, well dispersed CNC and CNCs not only increased the crystallinity but also improved the processability, the thermal stability and the interaction between both polymers especially in the case of the modified CNCs based PLA-PHB formulation. Likewise, CNCs were better dispersed in PLA-CNCs and PLA-PHB-CNCs, than CNC.

  7. Evaluation of biodegradable polymer conduits--poly(L-lactic acid)--for guiding sciatic nerve regeneration in mice.

    PubMed

    Goulart, Camila Oliveira; Lopes, Fátima Rosalina Pereira; Monte, Zulmira Oliveira; Dantas, Severino Valentim; Souto, Allana; Oliveira, Júlia Teixeira; Almeida, Fernanda Martins; Tonda-Turo, Chiara; Pereira, Cristina Cardoso; Borges, Cristiano Piacsek; Martinez, Ana Maria Blanco

    2016-04-15

    Polymeric biomaterials are often used for stimulating nerve regeneration. Among different conduits, poly(lactide acid) - PLA polymer is considered to be a good substrate due to its biocompatibility and resorbable characteristics. This polymer is an aliphatic polyester which has been mostly used in biomedical application. It is an organic compound with low allergenic potential, low toxicity, high biocompatibility and predictable kinetics of degradation. In this study we fabricated and evaluated a PLA microporous hollow fiber as a conduit for its ability to bridge a nerve gap in a mouse sciatic nerve injury model. The PLA conduit was prepared from a polymer solution, throughout extrusion technique. The left sciatic nerve of C57BL/6 mouse was transected and the nerve stumps were placed into a resorbable PLA (PLA group) or a PCL conduit (PCL group), n=5 each group. We have also used another group in which the nerves were repaired by autograft (autograft group, n=5). Motor function was analyzed according to sciatic functional index (SFI). After 56days, the regenerated nerves were processed for light and electron microscopy and morphometric analyses were performed. A quantitative analysis of regenerated nerves showed significant increase in the number of myelinated fibers and blood vessels in animals that received PLA conduit. The PLA group exhibited better overall tissue organization compared to other groups. Presenting well-organized bundles, many regenerating clusters composed of preserved nerve fibers surrounded by layers of compacted perineurium-like cells. Also the SFI revealed a significant improvement in functional recovery. This work suggests that PLA conduits are suitable substrate for cell survival and it provides an effective strategy to be used to support axonal growth becoming a potential alternative to autograft.

  8. Etude des melanges co-continus d'acide polylactique et d'amidon thermoplastique (PLA/TPS)

    NASA Astrophysics Data System (ADS)

    Chavez Garcia, Maria Graciela

    Les melanges co-continus sont des melanges polymeriques ou chaque composant se trouve dans une phase continue. Pour cette raison, les caracteristiques de chacun des composants se combinent et il en resulte un materiau avec une morphologie et des proprietes particulieres. L'acide polylactique (PLA) et l'amidon thermoplastique (TPS) sont des biopolymeres qui proviennent de ressources renouvelables et qui sont biodegradables. Dans ce projet, differents melanges de PLA et TPS a une haute concentration de TPS ont ete prepares dans une extrudeuse bi-vis afin de generer des structures co-continues. Grace a la technique de lixiviation selective, le TPS est enleve pour creer une structure poreuse de PLA qui a pu etre analysee au moyen de la microtomographie R-X et de la microscopie electronique a balayage MEB. L'analyse des images 2D et 3D confirme la presence de la structure co-continue dans les melanges dont la concentration en TPS. se situe entre 66% et 80%. L'effet de deux plastifiants, le glycerol seul et le melange de glycerol et de sorbitol, dans la formulation de TPS est etudie dans ce travail. De plus, nous avons evalue l'effet du PLA greffe a l'anhydride maleique (PLAg) en tant que compatibilisant. On a trouve que la phase de TPS obtenue avec le glycerol est plus grande. L'effet de recuit sur la taille de phases est aussi analyse. Grace aux memes techniques d'analyse, on a etudie l'effet du procede de moulage par injection sur la morphologie. On a constate que les pieces injectees presentent une microstructure heterogene et differente entre la surface et le centre de la piece. Pres de la surface, une peau plus riche en PLA est presente et les phases de TPS y sont allongees sous forme de lamelles. Plus au centre de la piece, une morphologie plus cellulaire est observee pour chaque phase continue. L'effet des formulations sur les proprietes mecaniques a aussi ete etudie. Les pieces injectees dont la concentration de TPS est plus grande presentent une moindre

  9. β-Lapachone-containing PEG-PLA Polymer Micelles as Novel Nanotherapeutics against NQO1-Overexpressing Tumor Cells

    PubMed Central

    Blanco, Elvin; Bey, Erik A.; Dong, Ying; Weinberg, Brent D.; Sutton, Damon M.; Boothman, David A.; Gao, Jinming

    2007-01-01

    β-Lapachone (β-lap) is a novel anticancer agent that is bioactivated by NADP(H): quinone oxidoreductase 1 (NQO1), an enzyme overexpressed in a variety of tumors. Despite its therapeutic promise, the poor aqueous solubility of β-lap hinders its preclinical evaluation and clinical translation. Our objective was to develop β-lap-containing poly(ethylene glycol)-block-poly(D,L-lactide) (PEG-PLA) polymer micelles for the treatment of NQO1-overexpressing tumors. Several micelle fabrication strategies were examined to maximize drug loading. A film sonication method yielded β-lap micelles with relatively high loading density (4.7 ± 1.0% to 6.5 ± 1.0%) and optimal size (29.6 ± 1.5 nm). Release studies in phosphate-buffered saline (pH 7.4) showed the time (t1/2) for 50% of drug release at 18 h. In vitro cytotoxicity assays were performed in NQO1-overexpressing (NQO1+) and NQO1-null (NQO1-) H596 lung, DU-145 prostate, and MDA-MB-231 breast cancer cells. Cytotoxicity data showed that after a 2 h incubation with β-lap micelles, a marked increase in toxicity was shown in NQO1+ cells over NQO1- cells, resembling free drug both in efficacy and mechanism of cell death. In summary, these data demonstrate the potential of β-lap micelles as an effective therapeutic strategy against NQO1-overexpressing tumor cells. PMID:17574288

  10. Cell responses and hemocompatibility of g-HA/PLA composites.

    PubMed

    Li, Jia; Zheng, Wei; Zheng, Yufeng; Lou, Xia

    2011-04-01

    The objective of this study was to investigate the hemocompatibility and cell responses to some novel poly(L-lactide) (PLA) composites containing surface modified hydroxyapatite particles for potential applications as a bone substitute material. The surface of hydroxyapatite (HA) particles was first grafted with L-lactic acid oligomers to form grafted HA (g-HA) particles. The g-HA particles were further blended with PLA to prepare g-HA/PLA composites. Our previous study has shown significant improvement in tensile properties of these materials due to the enhanced interfacial adhesion between the polymer matrix and HA particles. To further investigate the potential applications of these composites in bone repair and other orthopedic surgeries, a series of in vitro and in vivo experiments were conducted to examine the cell responses and hemocompatibility of the materials. In vitro experiments showed that the g-HA/PLA composites were well tolerated by the L-929 cells. Hemolysis of the composites was lower than that of pure PLA. Subcutaneous implantation demonstrated that the g-HA/PLA composites were more favorable than the control materials for soft tissue responses. The results suggested that the g-HA/PLA composites are promising and safe materials with potential applications in tissue engineering.

  11. Structural and Functional Studies of a Bothropic Myotoxin Complexed to Rosmarinic Acid: New Insights into Lys49-PLA2 Inhibition

    PubMed Central

    dos Santos, Juliana I.; Cardoso, Fábio F.; Soares, Andreimar M.; dal Pai Silva, Maeli; Gallacci, Márcia; Fontes, Marcos R. M.

    2011-01-01

    Snakebite envenoming is an important public health problem in many tropical and subtropical countries, and is considered a neglected tropical disease by the World Health Organization. Most severe cases are inflicted by species of the families Elapidae and Viperidae, and lead to a number of systemic and local effects in the victim. One of the main problems regarding viperidic accidents is prominent local tissue damage whose pathogenesis is complex and involves the combined actions of a variety of venom components. Phospholipases A2 (PLA2s) are the most abundant muscle-damaging components of these venoms. Herein, we report functional and structural studies of PrTX-I, a Lys49-PLA2 from Bothops pirajai snake venom, and the influence of rosmarinic acid (RA) upon this toxin's activities. RA is a known active component of some plant extracts and has been reported as presenting anti-myotoxic properties related to bothopic envenomation. The myotoxic activity of Lys49-PLA2s is well established in the literature and although no in vivo neurotoxicity has been observed among these toxins, in vitro neuromuscular blockade has been reported for some of these proteins. Our in vitro studies show that RA drastically reduces both the muscle damage and the neuromuscular blockade exerted by PrTX-I on mice neuromuscular preparations (by ∼80% and ∼90%, respectively). These results support the hypothesis that the two effects are closely related and lead us to suggest that they are consequences of the muscle membrane-destabilizing activity of the Lys49-PLA2. Although the C-terminal region of these proteins has been reported to comprise the myotoxic site, we demonstrate by X-ray crystallographic studies that RA interacts with PrTX-I in a different region. Consequently, a new mode of Lys49-PLA2 inhibition is proposed. Comparison of our results with others in the literature suggests possible new ways to inhibit bothropic snake venom myotoxins and improve serum therapy. PMID:22205953

  12. Feasibility study of prestressed natural fiber-reinforced polylactic acid (pla) composite materials

    NASA Astrophysics Data System (ADS)

    Hinchcliffe, Sean A.

    The feasibility of manufacturing prestressed natural-fiber reinforced biopolymer composites is demonstrated in this work. The objective of this study was to illustrate that the specific mechanical properties of biopolymers can be enhanced by leveraging a combination of additive manufacturing (3D printing) and post-tensioning of continuous natural fiber reinforcement. Tensile and flexural PLA specimens were 3D-printed with and without post-tensioning ducts. The mechanical properties of reinforcing fibers jute and flax were characterized prior to post-tensioning. The effect of matrix cross-sectional geometry and post-tensioning on the specific mechanical properties of PLA were investigated using mechanical testing. Numerical and analytical models were developed to predict the experimental results, which confirm that 3D-printed matrices improve the specific mechanical properties of PLA composites and are further improved via initial fiber prestressing. The results suggest that both additive manufacturing and fiber prestressing represent viable new methods for improving the mechanical performance of natural fiber-reinforced polymeric composites.

  13. Stabilization of PS/PLA cocontinuous blends by interfacial graphene

    NASA Astrophysics Data System (ADS)

    Bai, Lian; He, Siyao; Fruehwirth, John; Stein, Andreas; Cheng, Xiang; Macosko, Christopher

    Reduced graphene oxide (r-GO) is known to be effective in increasing the conductivity of cocontinuous polymer blends with a lower electrical percolation threshold. However, little is known regarding the localization and dynamics of r-GO along with morphology change during annealing. In this study, we develop a facile method to stabilize the polystyrene (PS)/polylactic acid (PLA) cocontinuous blends with r-GO jammed at interface. In this method, the non-functionalized GO is premixed with PLA via solvent method, and then reduced in-situ at 210oC to obtain a PLA/r-GO polymer composite. This composite is further mixed with PS via batch melt compounding. We observe the migration of r-GO from the PLA phase to the interface during annealing. The interfacial r-GO suppresses the coarsening of cocontinuous morphology and increases the conductivity of the filled polymer blend. Moreover, we systematically investigate the relationship between r-GO localization, rheological and conductivity change during annealing of r-GO filled PLA/PS blends. University of Minnesota Industrial Partnership for Research in Interfacial and Materials Engineering (IPRIME).

  14. Functionalized antibiofilm thin coatings based on PLA-PVA microspheres loaded with usnic acid natural compounds fabricated by MAPLE

    NASA Astrophysics Data System (ADS)

    Grumezescu, Valentina; Socol, Gabriel; Grumezescu, Alexandru Mihai; Holban, Alina Maria; Ficai, Anton; Truşcǎ, Roxana; Bleotu, Coralia; Balaure, Paul Cǎtǎlin; Cristescu, Rodica; Chifiriuc, Mariana Carmen

    2014-05-01

    We report the fabrication of thin coatings of PLA-PVA microspheres loaded with usnic acid by matrix assisted pulsed laser evaporation (MAPLE) onto Ti substrate. The obtained coatings have been physico-chemically characterized by scanning electron microscopy (SEM) and infrared microscopy (IRM). In vitro biological assays have been performed in order to evaluate the influence of fabricated microsphere thin coatings on the Staphylococcus aureus biofilm development as well as their biocompatibility. SEM micrographs have revealed a uniform morphology of thin coatings, while IRM investigations have proved both the homogeneity and functional groups integrity of prepared thin coatings. The obtained microsphere-based thin coatings have proved to be efficient vehicles for usnic acid natural compound with antibiofilm activity, as demonstrated by the inhibitory activity on S. aureus mature biofilm development, opening new perspectives for the prevention and therapy associated to biofilm related infections.

  15. Novel genipin-collagen immobilization of polylactic acid (PLA) fibers for use as tissue engineering scaffolds.

    PubMed

    Tambe, Nisarg; Di, Jin; Zhang, Ze; Bernacki, Susan; El-Shafei, Ahmed; King, Martin W

    2015-08-01

    The material surface plays an important role in the case of biomaterials used as tissue engineering scaffolds. On exposure to a biological environment, extra cellular matrix (ECM) proteins are adsorbed non-specifically onto the surface and cells interact indirectly with the surface through the adsorbed proteins. Most synthetic polymeric biomaterials lack the desirable surface properties for cells as well as have poor cellular adhesion due to their hydrophobic nature. The main objective of this study was to harness surface functionalization technologies to fabricate scaffolds that would be biocompatible and support the adhesion and proliferation of fibroblast cells. The collagen was immobilized on the surface of functionalized PLA via a novel natural cross-linking molecule genipin which resulted in improved cell proliferation of human dermal fibroblasts as compared to the PLA surface coated with collagen without genipin. It is believed that genipin helps reduce steric problems between the functional groups and large protein molecules, and enables immobilized peptide to move more freely in a biological environment.

  16. Polymer matrix effects on acid generation

    NASA Astrophysics Data System (ADS)

    Fedynyshyn, Theodore H.; Goodman, Russell B.; Roberts, Jeanette

    2008-03-01

    We have measured the acid generation efficiency with EUV exposure of a PAG in different polymer matrixes representing the main classes of resist polymers as well as some previously described fluoropolymers for lithographic applications. The polymer matrix was found to have a significant effect on the acid generation efficiency of the PAG studied. A linear relationship exists between the absorbance of the resist and the acid generation efficiency. A second inverse relationship exists between Dill C and aromatic content of the resist polymer. It was shown that polymer sensitization is important for acid generation with EUV exposure and the Dill C parameter can be increased by up to five times with highly absorbing non-aromatic polymers, such as non-aromatic fluoropolymers, over an ESCAP polymer. The increase in the Dill C value will lead to an up to five fold increase in resist sensitivity. It is our expectation that these insights into the nature of polymer matrix effects on acid generation could lead to increased sensitivity for EUV resists.

  17. Electrospraying and Electrospinning of Polymers for Biomedical Applications. Poly(Lactic-Co-Glycolic Acid) and Poly(Ethylene-Co-Vinylacetate). Appendix 2

    NASA Technical Reports Server (NTRS)

    Stitzel, Joel D.; Bowlin, Gary L.; Mansfield, Kevin; Wnek, Gary E.; Simpson, David G.

    2000-01-01

    Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. Specific attention is given here to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options. Of particular interest is the ability to generate polymer fibers of sub-micron dimensions using electrospinning, down to about 0.05 microns (50 nm), a size range that has been traditionally difficult to access. In our work, poly(lactic-co-glycolic acid), PLA/PGA, poly(lactic acid) PLA, and poly(ethylene-co-vinylacetate) (PEVA) have been deposited from solutions in methylene chloride or chloroform by electrospraying or electrospinning to afford morphologically tailored materials for tissue engineering and related applications. Low solution concentrations tend to favor electrostatic spraying ('electro-aerosolization') while higher concentrations lead to spinning on fibrous mats. Preliminary observations of muscle cell growth on PLA electrospun mats are reported.

  18. Biodegradable polymers derived from amino acids.

    PubMed

    Khan, Wahid; Muthupandian, Saravanan; Farah, Shady; Kumar, Neeraj; Domb, Abraham J

    2011-12-08

    In the past three decades, the use of polymeric materials has increased dramatically for biomedical applications. Many α-amino acids derived biodegradable polymers have also been intensely developed with the main goal to obtain bio-mimicking functional biomaterials. Polymers derived from α-amino acids may offer many advantages, as these polymers: (a) can be modified further to introduce new functions such as imaging, molecular targeting and drugs can be conjugated chemically to these polymers, (b) can improve on better biological properties like cell migration, adhesion and biodegradability, (c) can improve on mechanical and thermal properties and (d) their degradation products are expected to be non-toxic and readily metabolized/excreted from the body. This manuscript focuses on biodegradable polymers derived from natural amino acids, their synthesis, biocompatibility and biomedical applications. It is observed that polymers derived from α-amino acids constitute a promising family of biodegradable materials. These provide innovative multifunctional polymers possessing amino acid side groups with biological activity and with innumerous potential applications.

  19. A novel calcium-independent cellular PLA2 acts in insect immunity and larval growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phospholipase A2 (PLA2) catalyzes the position-specific hydrolysis of fatty acids linked to the sn-2 position of phospholipids (PLs). PLA2s make up a very large superfamily, with more than known 15 groups, classified into secretory PLA2 (sPLA2), Ca2+-dependent cellular PLA2 (sPLA2), and Ca2+-indepen...

  20. 78 FR 20029 - Castor Oil, Polymer With Adipic Acid, Linoleic Acid, Oleic Acid and Ricinoleic Acid; Tolerance...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-03

    ... AGENCY 40 CFR Part 180 Castor Oil, Polymer With Adipic Acid, Linoleic Acid, Oleic Acid and Ricinoleic..., polymer with adipic acid, linoleic acid, oleic acid and ricinoleic acid (CAS Reg. No. 1357486-09- 9) when used as an inert ingredient in a pesticide formulation. Advance Polymer Technology submitted a...

  1. Poly(lactic acid)-Mass production, processing, industrial applications, and end of life.

    PubMed

    Castro-Aguirre, E; Iñiguez-Franco, F; Samsudin, H; Fang, X; Auras, R

    2016-12-15

    Global awareness of material sustainability has increased the demand for bio-based polymers like poly(lactic acid) (PLA), which are seen as a desirable alternative to fossil-based polymers because they have less environmental impact. PLA is an aliphatic polyester, primarily produced by industrial polycondensation of lactic acid and/or ring-opening polymerization of lactide. Melt processing is the main technique used for mass production of PLA products for the medical, textile, plasticulture, and packaging industries. To fulfill additional desirable product properties and extend product use, PLA has been blended with other resins or compounded with different fillers such as fibers, and micro- and nanoparticles. This paper presents a review of the current status of PLA mass production, processing techniques and current applications, and also covers the methods to tailor PLA properties, the main PLA degradation reactions, PLA products' end-of-life scenarios and the environmental footprint of this unique polymer.

  2. [Elaboration of biodegradable polymer substrate for cultivation of human dermal fibroblasts].

    PubMed

    Shved, Iu A; Kukhareva, L V; Zorin, I M; Solov'ev, A Iu; Blinova, M I; Bilibin, A Iu; Pinaev, G P

    2006-01-01

    The influence of polylactic acid (PLA) surface films on the pattern of cell behavior was studied. The human dermal fibroblasts were cultivated on PLA covered glasses. The hydrophobic nature of PLA films depends on the availability of polymer solvent in the film preparation. PLA films obtained from a more polar solvent--aceton--appeared to be more hydrophilic than those obtained from methylene chloride. More hydrophilic polymer films also appeared to be more preferable for cell cultivation, and human dermal fibroblasts demonstrated a better adhesion and proliferation on hydrophilic rather than on hydrophobic PLA films.

  3. Fabrication and characterization of long-persistent luminescence/polymer (Ca2MgSi2O7:Eu2+, Dy3+/PLA) composite fibers by electrospinning

    NASA Astrophysics Data System (ADS)

    Ye, Feng; Dong, Shengjie; Tian, Zhe; Yao, Sijia; Zhou, Zhufa; Wang, Shumei

    2015-07-01

    Long-persistent luminescence /polymer (Ca2MgSi2O7:Eu2+, Dy3+/PLA) composite fibers have been fabricated via electrospinning method. The as-prepared one-dimensional fiber has been characterized by fluorescence microscope and distinct photographs have been obtained. The results show that the Ca2MgSi2O7:Eu2+, Dy3+ particles (12 wt%, size 200 nm) are uniformly dispersed in the PLA fibers (diameter 2.5 μm). It was found that the composite fibers have an emission band from 430 nm to 650 nm that peaks at 537 nm and 452 nm. Similarly, its phosphorescent emission spectra have similar features of luminescence (emission band from 430 nm to 650 nm that peaks at 537 nm and 452 nm). The decay curves of the composite fibers present a similar attenuate tendency with Ca2MgSi2O7:Eu2+, Dy3+ pure particles, but with lower intensity. The composite fiber has applications possibility in textile, display, optical detectors, indicator in the dark without electric energy which they never had before.

  4. Cloning and Sequence Analysis of cDNAs Encoding Two Acidic PLA(2) from venom of Ophiophagus hannah(King Cobra), Guangxi Species.

    PubMed

    Wang, Qiu-Yan; Shu, Yu-Yan; Zhuang, Mao-Xing; Lin, Zheng-Jiong

    2001-01-01

    Total RNA was extracted from venom glands of Ophiophagus hannah, Guangxi species. The cDNAs encoding PLA(2) were amplified by RT-PCR and cloned into the PUCm-T vector. The positive clones encoding two acidic PLA(2) (APLA(2)-1 and APLA(2)-2) were selected and bidirectionally sequenced. Their complete amino acid sequences were deduced and found to be identical to the known amino acid sequences. Their isoelectric points calculated by computer agreed with the values determined with their protein. Homology analysis indicated that the mature peptide of APLA(2)-1 had high homology with PLA(2) from venoms of Ophiophagus hannah, Fujian and Taiwan species, but APLA(2)-2 had lower homology. The most striking difference between APLA(2)-2 and other PLA(2) from Ophiophagus hannah venoms is the missing of a extra "pancreatic loop" at residues 62--66 in APLA(2)-2, and it may be related to their species evolution and biological activity.

  5. Fabrication of nanofibrous scaffold using a PLA and hagfish thread keratin composite; its effect on cell adherence, growth, and osteoblast differentiation.

    PubMed

    Kim, Beom-Su; Park, Ko Eun; Park, Won Ho; Lee, Jun

    2013-08-01

    Electrospinning is a useful method for the production of nanofibrous scaffolds in the field of tissue engineering. Keratin has been used as a biomaterial for electrospinning and can be used in a variety of biomedical applications because it is a natural protein, giving it the ability to improve cell affinity of scaffolds. In this study, keratin was extracted from hagfish slime thread (H-keratin) and blended with polylactic acid (PLA) polymer solution to construct a nanofibrous scaffold. Wool keratin (W-keratin) was used as a control for the comparison of morphological, physical, and biological properties. The results of Fourier transform infrared spectroscopy showed the presence of both W-keratin and H-keratin in the electrospun PLA/keratin. Observations with a scanning electron microscope revealed that PLA, PLA/W-keratin, and PLA/H-keratin had similar average diameters (~800 nm). Cell attachment experiments showed that MG-63 cells adhered more rapidly and spread better onto PLA/H-keratin than onto the pure PLA or PLA/W-keratin. Cell proliferation assay, DNA content, live/dead, and alkaline phosphatase activity assays showed that PLA/H-keratin scaffolds could accelerate the viability, proliferation, and osteogenesis of MG-63 cells relative to pure PLA or PLA/W-keratin nanofibrous scaffolds. These findings suggest that H-keratin can improve cellular attraction and has great potential to be used as a biomaterial in bone tissue engineering.

  6. Kinetics and mechanism of the biodegradation of PLA/clay nanocomposites during thermophilic phase of composting process.

    PubMed

    Stloukal, Petr; Pekařová, Silvie; Kalendova, Alena; Mattausch, Hannelore; Laske, Stephan; Holzer, Clemens; Chitu, Livia; Bodner, Sabine; Maier, Guenther; Slouf, Miroslav; Koutny, Marek

    2015-08-01

    The degradation mechanism and kinetics of polylactic acid (PLA) nanocomposite films, containing various commercially available native or organo-modified montmorillonites (MMT) prepared by melt blending, were studied under composting conditions in thermophilic phase of process and during abiotic hydrolysis and compared to the pure polymer. Described first order kinetic models were applied on the data from individual experiments by using non-linear regression procedures to calculate parameters characterizing aerobic composting and abiotic hydrolysis, such as carbon mineralization, hydrolysis rate constants and the length of lag phase. The study showed that the addition of nanoclay enhanced the biodegradation of PLA nanocomposites under composting conditions, when compared with pure PLA, particularly by shortening the lag phase at the beginning of the process. Whereas the lag phase of pure PLA was observed within 27days, the onset of CO2 evolution for PLA with native MMT was detected after just 20days, and from 13 to 16days for PLA with organo-modified MMT. Similarly, the hydrolysis rate constants determined tended to be higher for PLA with organo-modified MMT, particularly for the sample PLA-10A with fastest degradation, in comparison with pure PLA. The acceleration of chain scission in PLA with nanoclays was confirmed by determining the resultant rate constants for the hydrolytical chain scission. The critical molecular weight for the hydrolysis of PLA was observed to be higher than the critical molecular weight for onset of PLA mineralization, suggesting that PLA chains must be further shortened so as to be assimilated by microorganisms. In conclusion, MMT fillers do not represent an obstacle to acceptance of the investigated materials in composting facilities.

  7. Synthesis of ciprofloxacin-conjugated poly (L-lactic acid) polymer for nanofiber fabrication and antibacterial evaluation

    PubMed Central

    Parwe, Sharad P; Chaudhari, Priti N; Mohite, Kavita K; Selukar, Balaji S; Nande, Smita S; Garnaik, Baijayantimala

    2014-01-01

    Ciprofloxacin was conjugated with polylactide (PLA) via the secondary amine group of the piperazine ring using PLA and 7-(4-(2-Chloroacetyl) piperazin-1-yl)-1-cyclopropyl-6-fluoro-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid. Zinc prolinate, a biocompatible catalyst was synthesized, characterized, and used in ring opening polymerization of L-lactide. Five different kinds of OH-terminated poly(L-lactide) (two-, three-, four-, six-arm, star-shaped) homopolymers were synthesized by ring opening polymerization of L-lactide in the presence of dodecanol, glycerol, pentaerythritol, dipentaerythritol as initiator and zinc prolinate as a catalyst. The structures of the polymers and conjugates were thoroughly characterized by means of gel permeation chromatography, matrix-assisted laser desorption/ionization – time of flight mass spectrometry, and nuclear magnetic resonance spectroscopy. PLA (molecular weight =100,000) and ciprofloxacin conjugated PLA were used for fabrication of nonwoven nanofiber mat (diameter ranges; 150–400 nm) having pore size (62–102 nm) using electrospinning. The microbiological assessment shows that the release of ciprofloxacin possesses antimicrobial activity. The drug-release behavior of the mat was studied to reveal potential application as a drug delivery system. The result shows that the ciprofloxacin release rates of the PLA conjugate nonwoven nanofiber mat could be controlled by the drug loading content and the release medium. The development of a biodegradable ciprofloxacin system, based on nonwoven nanofiber mat, should be of great interest in drug delivery systems. PMID:24741303

  8. Lipase-catalyzed enantioselective synthesis of (R,R)-lactide from alkyl lactate to produce PDLA (poly D-lactic acid) and stereocomplex PLA (poly lactic acid).

    PubMed

    Jeon, Byoung Wook; Lee, Jumin; Kim, Hyun Sook; Cho, Dae Haeng; Lee, Hyuk; Chang, Rakwoo; Kim, Yong Hwan

    2013-10-20

    R-lactide, a pivotal monomer for the production of poly (D-lactic acid) (PDLA) or stereocomplex poly (lactic acid) (PLA) was synthesized from alkyl (R)-lactate through a lipase-catalyzed reaction without racemization. From among several types of lipase, only lipase B from Candida antarctica (Novozym 435; CAL-B) was effective in the reaction that synthesized (R,R)-lactide. Enantiopure (R,R)-lactide, which consisted of over 99% enantiomeric excess, was synthesized from methyl (R)-lactate through CAL-B catalysis. Removal of the methanol by-product was critical to obtain a high level of lactide conversion. The (R,R)-lactide yield was 56% in a reaction containing 100 mg of Novozym 435, 10 mM methyl (R)-lactate and 1500 mg of molecular sieve 5A in methyl tert-butyl ether (MTBE). The important monomer (R,R)-lactide that is required for the production of the widely recognized bio-plastic PDLA and the PLA stereocomplex can be obtained using this novel synthetic method.

  9. Synthesis of protein-coated biocompatible methotrexate-loaded PLA-PEG-PLA nanoparticles for breast cancer treatment

    PubMed Central

    Massadeh, Salam; Alaamery, Manal; Al-Qatanani, Shatha; Alarifi, Saqer; Bawazeer, Shahad; Alyafee, Yusra

    2016-01-01

    Background PLA-PEG-PLA triblock polymer nanoparticles are promising tools for targeted dug delivery. The main aim in designing polymeric nanoparticles for drug delivery is achieving a controlled and targeted release of a specific drug at the therapeutically optimal rate and choosing a suitable preparation method to encapsulate the drug efficiently, which depends mainly on the nature of the drug (hydrophilic or hydrophobic). In this study, methotrexate (MTX)-loaded nanoparticles were prepared by the double emulsion method. Method Biodegradable polymer polyethylene glycol-polylactide acid tri-block was used with poly(vinyl alcohol) as emulsifier. The resulting methotrexate polymer nanoparticles were coated with bovine serum albumin in order to improve their biocompatibility. This study focused on particle size distribution, zeta potential, encapsulation efficiency, loading capacity, and in vitro drug release at various concentrations of PVA (0.5%, 1%, 2%, and 3%). Results Reduced particle size of methotrexate-loaded nanoparticles was obtained using lower PVA concentrations. Enhanced encapsulation efficiency and loading capacity was obtained using 1% PVA. FT-IR characterization was conducted for the void polymer nanoparticles and for drug-loaded nanoparticles with methotrexate, and the protein-coated nanoparticles in solid state showed the structure of the plain PEG-PLA and the drug-loaded nanoparticles with methotrexate. The methotrexate-loaded PLA-PEG-PLA nanoparticles have been studied in vitro; the drug release, drug loading, and yield are reported. Conclusion The drug release profile was monitored over a period of 168 hours, and was free of burst effect before the protein coating. The results obtained from this work are promising; this work can be taken further to develop MTX based therapies.

  10. Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

    NASA Astrophysics Data System (ADS)

    Rose, A. S. J. Lucia; Selvarajan, P.; Perumal, S.

    2011-10-01

    Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm × 12 mm × 8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

  11. Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals.

    PubMed

    Rose, A S J Lucia; Selvarajan, P; Perumal, S

    2011-10-15

    Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

  12. Improving the engineering properties of PLA for 3D printing and beyond

    NASA Astrophysics Data System (ADS)

    Rocha Gutierrez, Carmen Raquel

    Additive manufacturing (AM), now more commonly known as 3D printing, has been classified as efficient, fast, and practical in the prototyping sector of product development. In the work presented here, we will use one of the AM techniques known as Material extrusion 3D printing (ME3DP), which has all the advantages of AM. However, one of the biggest challenges facing ME3DP technologies is the limitation of the range of materials used by this technique. Acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) are currently the most common thermoplastics materials used in ME3DP because of their ability to melt and be reprocessed. PLA is a biodegradable polymer derived from renewable sources such as corn, and sugarcane. The expanded use of this polymer over traditional petroleum-based plastics (ABS) will decrease the demand on petrochemicals, and also lead to less non-biodegradable polymeric waste. While PLA offers an eco-friendly solution for polymeric 3D printing, the mechanical performance is limited by PLA's inherent characteristics (such as moisture absorbance) that may degrade the plastic during processing. PLA novel systems were used through this research maintaining the compatibility with material extrusion 3D printers. The purpose of this investigation is to alter the physical properties of PLA with sustainable additives in order to improve the end use products from this material.

  13. Circulating n-3 fatty acids and trans-fatty acids, PLA2G2A gene variation and sudden cardiac arrest.

    PubMed

    Lemaitre, Rozenn N; Bartz, Traci M; King, Irena B; Brody, Jennifer A; McKnight, Barbara; Sotoodehnia, Nona; Rea, Thomas D; Johnson, Catherine O; Mozaffarian, Dariush; Hesselson, Stephanie; Kwok, Pui-Yan; Siscovick, David S

    2016-01-01

    Whether genetic factors influence the associations of fatty acids with the risk of sudden cardiac arrest (SCA) is largely unknown. To investigate possible gene-fatty acid interactions on SCA risk, we used a case-only approach and measured fatty acids in erythrocyte samples from 1869 SCA cases in a population-based repository with genetic data. We selected 191 SNP in ENCODE-identified regulatory regions of fifty-five candidate genes in fatty acid metabolic pathways. Using linear regression and additive genetic models, we investigated the association of the selected SNP with erythrocyte levels of fatty acids, including DHA, EPA and trans-fatty acids among the SCA cases. The assumption of no association in non-cases was supported by analysis of publicly available datasets containing over 8000 samples. None of the SNP-fatty acid associations tested among the cases reached statistical significance after correction for multiple comparisons. One SNP, rs4654990 near PLA2G2A, with an allele frequency of 0·33, was nominally associated with lower levels of DHA and EPA and higher levels of trans-fatty acids. The strongest association was with DHA levels (exponentiated coefficient for one unit (1 % of total fatty acids), 0·90, 95 % CI 0·85, 0·97; P = 0·003), indicating that for subjects with a coded allele, the OR of SCA associated with one unit higher DHA is about 90 % what it is for subjects with one fewer coded allele. These findings suggest that the associations of circulating n-3 and trans-fatty acids with SCA risk may be more pronounced in carriers of the rs4654990 G allele.

  14. Effect of platy and tubular nanoclays on behaviour of biodegradable PCL/PLA blend and related microfibrillar composites

    NASA Astrophysics Data System (ADS)

    Kelnar, Ivan; Kratochvíl, Jaroslav

    2016-05-01

    Blending of ductile poly(ɛ-caprolactone) (PCL) and rigid polylactic acid (PLA) is a promising way to tailor biodegradable materials with broad range of properties. But the mutual incompatibility of both polyesters leads to compromised behaviour only. Alternative to PCL/PLA blends is application of PLA in the form of short fibres, however, difficult dispergation of flexible fibres including their poor adhesion and limited processing is a significant restriction. More effective is in situ formation of polymeric fibre-reinforced materials using microfibrillar composites (MFC) concept based on melt- or cold-drawing of a polymer blend. Important advantage of MFC is efficient dispersion and bonding of in-situ formed reinforcing fibres This work deals with combination of structure-directing and reinforcing effects of montmorillonite (oMMT) and halloysite nanotubes (HNT) in the PCL/PLA 80/20 blend with in-situ formation of PLA fibrils in the PCL matrix. In the resulting microfibrillar composite, reinforcement by rigid PLA fibrils is combined with strengthening of both components by the nanofiller (NF). Moreover, PLA fibrils formation via melt-drawing is only possible after nanofiller addition due to favourable affecting of rheological parameters of the polymer components. The structure-properties relationship and complex effect of NF on microfibrillar composite performance, causing e.g., quite comparable parameters of both microfibrillar composites in spite of lower reinforcing effect of halloysite nanotubes on components, are discussed.

  15. Thermoset polymer-layered silicic acid nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Zhen

    Nanocomposites are formed when phase mixing occurs on a nanometer length scale. Due to the improved phase morphology and interfacial properties, nanocomposites exhibit mechanical properties superior to conventional composites. Toyota researchers first demonstrated that organoclay could be exfoliated in a nylon-6 matrix to greatly improve the thermal and mechanical properties of the polymer, which has resulted in a practical application in the automobile industry. A great deal of research has been conducted on organic-inorganic hybrid composites in which smectite clays are used as reinforcement agents. However, little work has been devoted to derivatives of other layered inorganic solids. In the present work, the first examples of organic polymer-layered silicic acid nanocomposites have been prepared by formation of a cured epoxy polymer network in the presence of organo cation exchange forms of magadiite. The exfoliation of silicate nanolayers in the epoxy matrix was achieved by in-situ intragallery polymerization during the thermosetting process. In general, the tensile properties, solvent resistance, barrier properties and chemical stability of the polymer matrix are greatly improved by the embedded silicate nanolayers when the matrix is flexible (sub-ambient Tg). The improvement of properties are dependent on the silicate loading, the degree of nanolayer separation and interfacial properties. Interestingly, the exfoliation also affects the polymer elasticity in a favorable way. The mechanism leading to nanocomposite formation is proposed. One exfoliated epoxy-magadiite nanocomposite/composition possessed unique transparent optical properties. The exfoliation chemistry was successfully extended to the other members of the layered silicic acid family. A new approach also was developed to prepare thermoset epoxy polymer-layered silicate nanocomposites in which curing agents can be directly intercalated into the intragallery without the need for alkylammonium ions

  16. Curcumin-Loaded PLA Nanoparticles: Formulation and Physical Evaluation

    PubMed Central

    Rachmawati, Heni; Yanda, Yulia L.; Rahma, Annisa; Mase, Nobuyuki

    2016-01-01

    Curcumin is a polyphenolic compound derived from Curcuma domestica (Zingiberaceae) that possesses diverse pharmacological effects including anti-inflammatory, antioxidant, antimicrobial, and anticarcinogenic activities. Although phase I clinical trials have shown curcumin as a safe drug even at high doses (12 g/day) in humans, poor bioavaibility largely limits its pharmacological activity. Nanoencapsulation in biodegradable polymers is a promising alternative to improve curcumin bioavaibility. In this study, curcumin was encapsulated in biodegradable polymer poly-(lactic acid) (PLA) nanoparticles via the emulsification-solvent evaporation method. Optimization of selected parameters of this method including the type of solvent, surfactant concentration, drug loading, sonication time, and centrifugation speed, were performed to obtain polymeric nano-carriers with optimum characteristics. Dichloromethane was used as the solvent and vitamin E polyethylene glycol succinate (TPGS) was used as the surfactant. Four minutes of sonication time and centrifugation at 10500 rpm were able to produce spherical nanoparticles with average size below 300 nm. The highest encapsulation efficiency was found on PLA nanoparticles containing 5% of curcumin at 89.42 ± 1.04%. The particle size, polydispersity index, zeta potential of 5% curcumin-PLA nanoparticles were 387.50 ± 58.60 nm, 0.289 ± 0.047, and −1.12 mV, respectively. Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) studies showed partial interaction between the drug and polymer. PMID:27110509

  17. Fabrication and characterization of poly(lactic acid)/acetyl tributyl citrate/carbon black as conductive polymer composites.

    PubMed

    Yu, Jiugao; Wang, Ning; Ma, Xiaofei

    2008-03-01

    By using acetyl tributyl citrate (ATBC) as the plasticizer of poly(lactic acid) (PLA) and carbon black (CB) as conductive filler, electrically conductive polymer composites (CPC) with different CB and ATBC contents were prepared. FTIR revealed that the interaction existed between PLA/ATBC matrix and CB filler and ATBC could improve this interaction. The rheology showed that ATBC could obviously decrease the shear viscosity and improve the fluidity of the composites but just the reverse for CB. With the increasing of CB contents, the enforcement effect, storage modulus, and glass-transition temperature increased but the elongation at break decreased. PLA/ATBC/CB composites exhibited the low electrical percolation thresholds of 0.516, 1.20, 2.46, and 2.74 vol % CB at 30, 20, 10, and 0 wt % ATBC. The conductivity of the composite containing 3.98 vol % CB and 30 wt % ATBC reached 1.60 S/cm. Scanning electron microscopy revealed that the addition of ATBC facilitated the dispersion of the CB in the PLA matrix. Water vapor permeability (WVP) showed that, at the same CB contents, the more ATBC contents there were, the less the values of WVP were.

  18. PLA composites: From production to properties.

    PubMed

    Murariu, Marius; Dubois, Philippe

    2016-12-15

    Poly(lactic acid) or polylactide (PLA), a biodegradable polyester produced from renewable resources, is used for various applications (biomedical, packaging, textile fibers and technical items). Due to its inherent properties, PLA has a key-position in the market of biopolymers, being one of the most promising candidates for further developments. Unfortunately, PLA suffers from some shortcomings, whereas for the different applications specific end-use properties are required. Therefore, the addition of reinforcing fibers, micro- and/or nanofillers, and selected additives within PLA matrix is considered as a powerful method for obtaining specific end-use characteristics and major improvements of properties. This review highlights recent developments, current results and trends in the field of composites based on PLA. It presents the main advances in PLA properties and reports selected results in relation to the preparation and characterization of the most representative PLA composites. To illustrate the possibility to design the properties of composites, a section is devoted to the production and characterization of innovative PLA-based products filled with thermally-treated calcium sulfate, a by-product from the lactic acid production process. Moreover, are emphasized the last tendencies strongly evidenced in the case of PLA, i.e., the high interest to diversify its uses by moving from biomedical and packaging (biodegradation properties, "disposables") to technical applications ("durables").

  19. Plasticized poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends incorporated with catechin intended for active food-packaging applications.

    PubMed

    Arrieta, Marina Patricia; Castro-López, María del Mar; Rayón, Emilio; Barral-Losada, Luis Fernando; López-Vilariño, José Manuel; López, Juan; González-Rodríguez, María Victoria

    2014-10-15

    Active biobased packaging materials based on poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends were prepared by melt blending and fully characterized. Catechin incorporation, as antioxidant compound, enhanced the thermal stability, whereas its release was improved by the addition of acetyl(tributyl citrate) (ATBC) as plasticizer. Whereas the incorporation of ATBC resulted in a reduction of elastic modulus and hardness, catechin addition produced more rigid materials due to hydrogen-bonding interactions between catechin hydroxyl groups and carbonyl groups of PLA and PHB. The quantification of catechin released into a fatty food simulant and the antioxidant effectiveness after the release process were demonstrated. The effect of the materials' exposure to a food simulant was also investigated. PHB-added materials maintained their structural and mechanical properties after 10 days in a test medium that represents the worst foreseeable conditions of the intended use. Thus, plasticized PLA-PHB blends with catechin show their potential as biobased active packaging for fatty food.

  20. Carbohydrate Polymers for Nonviral Nucleic Acid Delivery

    PubMed Central

    Sizovs, Antons; McLendon, Patrick M.; Srinivasachari, Sathya

    2014-01-01

    Carbohydrates have been investigated and developed as delivery vehicles for shuttling nucleic acids into cells. In this review, we present the state of the art in carbohydrate-based polymeric vehicles for nucleic acid delivery, with the focus on the recent successes in preclinical models, both in vitro and in vivo. Polymeric scaffolds based on the natural polysaccharides chitosan, hyaluronan, pullulan, dextran, and schizophyllan each have unique properties and potential for modification, and these results are discussed with the focus on facile synthetic routes and favorable performance in biological systems. Many of these carbohydrates have been used to develop alternative types of biomaterials for nucleic acid delivery to typical polyplexes, and these novel materials are discussed. Also presented are polymeric vehicles that incorporate copolymerized carbohydrates into polymer backbones based on polyethylenimine and polylysine and their effect on transfection and biocompatibility. Unique scaffolds, such as clusters and polymers based on cyclodextrin (CD), are also discussed, with the focus on recent successes in vivo and in the clinic. These results are presented with the emphasis on the role of carbohydrate and charge on transfection. Use of carbohydrates as molecular recognition ligands for cell-type specific delivery is also briefly reviewed. We contend that carbohydrates have contributed significantly to progress in the field of non-viral DNA delivery, and these new discoveries are impactful for developing new vehicles and materials for treatment of human disease. PMID:21504102

  1. Stereocomplexes of enantiomeric lactic acid and sebacic acid ester-anhydride triblock copolymers.

    PubMed

    Slivniak, Raia; Domb, Abraham J

    2002-01-01

    A systematic study on the synthesis, characterization, degradation, and drug release of d-, l-, and dl-poly(lactic acid) (PLA)-terminated poly(sebacic acid) (PSA) and their stereocomplexes is reported. PLA-terminated sebacic acid polymers were synthesized by melt condensation of the acetate anhydride derivatives of PLA oligomers and sebacic anhydride oligomers to yield ABA triblock copolymers of molecular weights between 3000 and 9000 that melt at temperatures between 35 and 80 degrees C. Pairs of the corresponding enantiomeric ABA copolymers composed of l-PLA-PSA-l-PLA and d-PLA-PSA-d-PLA were solvent mixed to form stereocomplexes. The formed stereocomplexes exhibited higher crystalline melting temperature than the enantiomeric polymers, which indicate stereocomplex formulation. The PLA terminals had a significant effect on the polymer degradation and drug release rate. PSA with up to 20% w/w of PLA terminals degraded and released the incorporated drug for more than 3 weeks as compared with 10 days for PSA homopolymer.

  2. Electrospun fibers of PLA/P3HT blends for device and sensor applications

    NASA Astrophysics Data System (ADS)

    Serrano, William; Pinto, Nicholas

    2013-03-01

    The thermoplastic aliphatic polyester, poly (lactic acid) (PLA) is a biodegradable polymer that is sometimes used in implant screws for bone repair. Our focus was to fabricate fibers of this polymer and its blends with p-doped poly (3-hexylthiophene)-(P3HT) in order to extend its use to devices and/or sensors. PLA/P3HT fibers were prepared in air at room temperature using the electrospinning technique that is cheap, fast and reliable. Scanning Electron Microscope images of the fibers reveal that the presence of P3HT does not affect the fabrication of PLA fibers at low or high polymer concentrations in chloroform, retaining the same morphological structure of pure PLA fibers. The fiber diameters were in the range 1-10 microns. A slight increase in fiber formation results with the addition of P3HT, most likely due to a reduction of the solution surface tension. Results of the electrical characterization of this material will be presented. DoD and NSF

  3. In vitro degradation kinetics of pure PLA and Mg/PLA composite: Effects of immersion temperature and compression stress.

    PubMed

    Li, Xuan; Chu, Chenglin; Wei, Yalin; Qi, Chenxi; Bai, Jing; Guo, Chao; Xue, Feng; Lin, Pinghua; Chu, Paul K

    2017-01-15

    The effects of the immersion temperature and compression stress on the in vitro degradation behavior of pure poly-lactic acid (pure-PLA) and PLA-based composite unidirectionally reinforced with micro-arc oxidized magnesium alloy wires (Mg/PLA or MAO-MAWs/PLA) are investigated. The degradation kinetics of pure-PLA and the PLA matrix in MAO-MAWs/PLA exhibit an Arrhenius-type behavior. For the composite, the synergic degradation of MAO-MAWs maintains a steady pH and mitigates the degradation of PLA matrix during immersion. However, the external compression stress decreases the activation energy (Ea) and pre-exponential factor (k0) consequently increasing the degradation rate of PLA. Under a compression stress of 1MPa, Ea and k0 of pure PLA are 57.54kJ/mol and 9.74×10(7)day(-1), respectively, but 65.5kJ/mol and 9.81×10(8)day(-1) for the PLA matrix in the composite. Accelerated tests are conducted in rising immersion temperature in order to shorten the experimental time. Our analysis indicates there are well-defined relationships between the bending strength of the specimens and the PLA molecular weight during immersion, which are independent of the degradation temperature and external compression stress. Finally, a numerical model is established to elucidate the relationship of bending strength, the PLA molecular weight, activation energy, immersion time and temperature.

  4. Extra-hepatic metabolism of 7-ketocholesterol occurs by esterification to fatty acids via cPLA2α and SOAT1 followed by selective efflux to HDL.

    PubMed

    Lee, Jung Wha; Huang, Jiahn-Dar; Rodriguez, Ignacio R

    2015-05-01

    Accumulation of 7-ketocholesterol (7KCh) in tissues has been previously associated with various chronic aging diseases. Orally ingested 7KCh is readily metabolized by the liver and does not pose a toxicity threat. However, 7KCh formed in situ, usually associated with lipoprotein deposits, can adversely affect surrounding tissues by causing inflammation and cytotoxicity. In this study we have investigated various mechanisms for extra-hepatic metabolism of 7KCh (e.g. hydroxylation, sulfation) and found only esterification to fatty acids. The esterification of 7KCh to fatty acids involves the combined action of cytosolic phospholipase A2 alpha (cPLA2α) and sterol O-acyltransferase (SOAT1). Inhibition of either one of these enzymes ablates 7KCh-fatty acid ester (7KFAE) formation. The 7KFAEs are not toxic and do not induce inflammatory responses. However, they can be unstable and re-release 7KCh. The higher the degree of unsaturation, the more unstable the 7KFAE (e.g. 18:0>18:1>18:2>18:3≫20:4). Biochemical inhibition and siRNA knockdown of SOAT1 and cPLA2α ablated the 7KFAE synthesis in cultured ARPE19 cells, but had little effect on the 7KCh-induced inflammatory response. Overexpression of SOAT1 reduced the 7KCh-induced inflammatory response and provided some protection from cell death. This effect is likely due to the increased conversion of 7KCh to 7KFAEs, which reduced the intracellular 7KCh levels. Addition of HDL selectively increased the efflux of 7KFAEs and enhanced the effect of SOAT1 overexpression. Our data suggests an additional function for HDL in aiding extra-hepatic tissues to eliminate 7KCh by returning 7KFAEs to the liver for bile acid formation.

  5. Bioprocessing of glycerol into glyceric Acid for use in bioplastic monomer.

    PubMed

    Fukuoka, Tokuma; Habe, Hiroshi; Kitamoto, Dai; Sakaki, Keiji

    2011-01-01

    Utilization of excess glycerol supplies derived from the burgeoning biodiesel industry has recently become very important. Glyceric acid (GA) is one of the most promising glycerol derivatives, and it is abundantly obtained from glycerol by a bioprocess using acetic acid bacteria. In this study, a novel branched-type poly(lactic acid) (PLA) was synthesized by polycondensation of lactide in the presence of GA. The resulting branched PLA had lower crystallinity and glass transition temperatures than the conventional linear PLA, and the peak associated with the melting point of the branched PLA disappeared. Moreover, in a blend of the branched polymer, the crystallization of the linear PLA occurred at a lower temperature. Thus, the branched PLA containing GA synthesized in this study could potentially be used as a novel bio-based modifier for PLA.

  6. PLA micro- and nano-particles.

    PubMed

    Lee, Byung Kook; Yun, Yeonhee; Park, Kinam

    2016-12-15

    Poly(d,l-lactic acid) (PLA) has been widely used for various biomedical applications for its biodegradable, biocompatible, and nontoxic properties. Various methods, such as emulsion, salting out, and precipitation, have been used to make better PLA micro- and nano-particle formulations. They are widely used as controlled drug delivery systems of therapeutic molecules, including proteins, genes, vaccines, and anticancer drugs. Even though PLA-based particles have challenges to overcome, such as low drug loading capacity, low encapsulation efficiency, and terminal sterilization, continuous innovations in particulate formulations will lead to development of clinically useful formulations.

  7. Hyperbranched chelating polymers for the polymer-assisted ultrafiltration of boric acid

    SciTech Connect

    Smith, B.M.; Todd, P.; Bowman, C.N.

    1999-07-01

    Two hyperbranched chelating polymers, glucoheptonamide derivatives of dendrimetric poly(amido amine) and poly(ethylene imine), were employed in polymer-assisted ultrafiltration and concentration of boron from aqueous feed streams. For feeds containing approximately 1 mM B (10 ppm), volume reduction factors of 20 were observed in cyclic adsorption-desorption. The concentrations of both polymers declined due to permeation through an ultrafiltration membrane with pore sizes which should have retained them. Acid-catalyzed hydrolysis of the amide linkages between the polymer backbone and the chelating side groups is implicated in this loss of polymer mass and effectiveness.

  8. Effect of filler loading of nickel zinc ferrite on the tensile properties of PLA nanocomposites

    NASA Astrophysics Data System (ADS)

    Shahdan, Dalila; Ahmad, Sahrim Hj

    2013-05-01

    The mechanical strength of magnetic polymer nanocomposite (MPNC) of nickel zinc (NiZn) ferrite nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer is reported. The matrix was prepared from PLA and LNR in the ratio of 90:10. The MPNC were prepared at constant mixing temperature at 180°C, mixing time of 15 min. and mixing speed of 100 rpm. In order to achieve a good dispersion of NiZn ferrite in the matrix, firstly an ultrasonic treatment had been employed to mix the LNR and NiZn ferrite for 1 hour. The MPNC of PLA/LNR/NiZn ferrite then were prepared via Thermo Haake internal mixer using melt-blending method from different filler loading from 1-5 wt% NiZn ferrite. The result of tensile tests showed that as the filler loading increases the tensile strength also increases until an optimum value of filler loading was reached. The Young's modulus, tensile strength and elongation at break have also increased. The study proves that NiZn ferrite is excellent reinforcement filler in PLA matrix. Scanning electron micrograph (SEM) and energy dispersive X-ray spectroscopy (EDX) were meant to show the homogeneity dispersion of nanoparticles within the matrix and to confirm the elemental composition of NiZn ferrites-PLA/LNR nanocomposites respectively.

  9. Effects of screw speed on the properties of plasticized PLA/POSS composites

    NASA Astrophysics Data System (ADS)

    Kodal, M.; Sirin, H.; Ozkoc, G.

    2014-05-01

    The effect of screw speed on the flow behavior, mechanical, thermal and morphological properties of the melt compounded plasticized poly(lactic acid) (PLA)/polyhedral oligomeric silsesquioxanes (POSS) composites were investigated. Two types of POSS-aminopropylisobutyl-POSS (A-POSS) as the reactive one and the octaisobutyl-POSS (O-POSS) as the non-reactive one, were used at 1-10 wt% filler loadings. Poly(ethylene glycol) (PEG-8000 g/moles) was utilized as a plasticizer. PEG amount was kept constant at 10 wt% with respect to PLA. To investigate the compounding conditions on the properties of the composites, two different screw speeds (100 and 200 rpm) were used. It was found that incorporation of POSS particles to the PLA decreased the melt viscosity of the composites due to the slip-agent behavior of POSS molecules. The mechanical test results showed that composites compounded at 100 rpm have higher yield strength and modulus values. Moreover, a significant improvement in Izod impact strength of plasticized PLA composites compounded at 100 rpm was obtained (regardless of POSS type). SEM analysis showed that POSS particles dispersed homogeneously in polymer matrix at all loadings regardless of screw speed. It was revealed from DSC that POSS particles acted as a nucleating agent for PLA/PEG independently from mixing conditions. Moreover, the percent crystallinity was found to be higher in the presence of POSS.

  10. pH-responsive biocompatible fluorescent polymer nanoparticles based on phenylboronic acid for intracellular imaging and drug delivery

    NASA Astrophysics Data System (ADS)

    Li, Shengliang; Hu, Kelei; Cao, Weipeng; Sun, Yun; Sheng, Wang; Li, Feng; Wu, Yan; Liang, Xing-Jie

    2014-10-01

    To address current medical challenges, there is an urgent need to develop drug delivery systems with multiple functions, such as simultaneous stimuli-responsive drug release and real-time imaging. Biocompatible polymers have great potential for constructing smart multifunctional drug-delivery systems through grafting with other functional ligands. More importantly, novel biocompatible polymers with intrinsic fluorescence emission can work as theranostic nanomedicines for real-time imaging and drug delivery. Herein, we developed a highly fluorescent nanoparticle based on a phenylboronic acid-modified poly(lactic acid)-poly(ethyleneimine)(PLA-PEI) copolymer loaded with doxorubicin (Dox) for intracellular imaging and pH-responsive drug delivery. The nanoparticles exhibited superior fluorescence properties, such as fluorescence stability, no blinking and excitation-dependent fluorescence behavior. The Dox-loaded fluorescent nanoparticles showed pH-responsive drug release and were more effective in suppressing the proliferation of MCF-7 cells. In addition, the biocompatible fluorescent nanoparticles could be used as a tool for intracellular imaging and drug delivery, and the process of endosomal escape was traced by real-time imaging. These pH-responsive and biocompatible fluorescent polymer nanoparticles, based on phenylboronic acid, are promising tools for intracellular imaging and drug delivery.To address current medical challenges, there is an urgent need to develop drug delivery systems with multiple functions, such as simultaneous stimuli-responsive drug release and real-time imaging. Biocompatible polymers have great potential for constructing smart multifunctional drug-delivery systems through grafting with other functional ligands. More importantly, novel biocompatible polymers with intrinsic fluorescence emission can work as theranostic nanomedicines for real-time imaging and drug delivery. Herein, we developed a highly fluorescent nanoparticle based on a

  11. PLA branching with anhydrides and tri-functional aziridine

    NASA Astrophysics Data System (ADS)

    Gu, Liangliang; Xu, Yuewen; Naredla, Rajasekhar; Hoye, Thomas; Macosko, Christopher

    Branched PLA was prepared by melt blending with tri-functional aziridine (T-Az) and pyromellitic dianhydride (PMDA). 1HNMR, gel permeation chromatography (GPC) and rheology were used to characterize the topological structures of branched PLA. Fast reaction between PLA carboxyl end group and T-Az resulted in 3-arm stars and increased the molecular weight. However, the 3-arm stars did not show strain hardening behavior under extensional flow. After modifying PLA hydroxyl end group with PMDA, PLA can react with T-Az on both chain ends and form long chain branched structure, which showed strain hardening in extension. It was found that that only 10% of the PLA hydroxyl end groups reacted with PMDA. This work is supported by Center for Sustainable Polymers.

  12. The effect of the stretching of PLA extruded films on their crystallinity and gas barrier properties

    NASA Astrophysics Data System (ADS)

    Guinault, A.; Menary, G. H.; Courgneau, C.; Griffith, D.; Ducruet, V.; Miri, V.; Sollogoub, C.

    2011-05-01

    Driven by environmental concerns, new polymers based on renewable resources are arriving on the market to replace conventional polymers, obtained from petroleum, for different applications like food packaging. One of the most prominent polymers among these materials is poly(lactic acid) (PLA), a biodegradable, thermoplastic, aliphatic polyester derived from renewable resources, such as corn starch (in the USA) or sugarcanes (in the rest of the world). However this polymer presents different disadvantages and especially low gas barrier properties [1]. Thermal crystallization can be used to increase its gas barrier properties but long times are necessary [2] and are not compatible with an industrial process. Another way to increase the gas barrier properties consists in stretching the film in order to increase its crystallinity and so its diffusion coefficient. We have prepared stretched PLA films with different stretch ratio and we have studied the effect of the stretching parameters on the gas barrier properties of PLA films. Finally we compared this process with the isothermal crystallization process by taking into account the crystallinity degree and the crystalline morphology.

  13. Thermochemical study of amino acid imprinted polymer films.

    PubMed

    Chai, Ziyi; BelBruno, Joseph J

    2015-11-01

    Molecularly imprinted polymers provide an alternative to traditional methods of amino acid analysis. The imprinted polymers are more robust and significantly less expensive than, for example, ELISA analysis. Amino acid imprinted nylon-6 thin films were studied by differential scanning calorimetry and scanning electron microscopy. Endothermic peaks were observed for imprinted films at temperatures higher than that for pure nylon, indicating the formation of a more-ordered, hydrogen bonded polymer. Removal of the amino acid from the imprinted film resulted in reversion to the peak observed for pure nylon-6. Additives, β-cyclodextrin and multiwalled carbon nanotubes, were added to the imprinted polymer solutions as a means to increase the porosity of the films. These studies resulted in alternative morphologies and calorimetric results that provide additional functionalities and applications for imprinted polymers.

  14. Comportement en fatigue et influence de la temperature sur les proprietes en traction du PLA

    NASA Astrophysics Data System (ADS)

    Menard, Claire

    Current environmental issues reduce the use of materials obtained from fossil resources. The usual plastics therefore tend to be replaced by more green polymers such as polylactic acid (PLA), a bio-based and biodegradable polymer. Knowledge on the properties of this material is essential, especially in terms of fatigue strength and influence of temperature on tensile stiffness and strength. In this study, the PLA samples are submitted to monotonic tensile tests, according to ASTM D638-10, at various temperatures between room temperature (23°C) and the glass transition temperature of the material (55-60°C). The results show a decrease of 30% of the modulus of elasticity and 60% of the tensile strength between these two temperatures. This decrease is mainly due to a significant drop in the mechanical properties beyond 50°C. In addition, tensile fatigue tests were conducted at loads rate between 40 and 80% of tensile strength, at room temperature in order to plot the Wohler curve of PLA. The ruptured specimens were finally observed with a scanning electron microscope (SEM) to analyze the failure mechanisms in fatigue of PLA.

  15. Electrical characterization of proton conducting polymer electrolyte based on bio polymer with acid dopant

    NASA Astrophysics Data System (ADS)

    Kalaiselvimary, J.; Pradeepa, P.; Sowmya, G.; Edwinraj, S.; Prabhu, M. Ramesh

    2016-05-01

    This study describes the biodegradable acid doped films composed of chitosan and Perchloric acid with different ratios (2.5 wt %, 5 wt %, 7.5 wt %, 10 wt %) was prepared by the solution casting technique. The temperature dependence of the proton conductivity of complex electrolytes obeys the Arrhenius relationship. Proton conductivity of the prepared polymer electrolyte of the bio polymer with acid doped was measured to be approximately 5.90 × 10-4 Scm-1. The dielectric data were analyzed using Complex impedance Z*, Dielectric loss ɛ', Tangent loss for prepared polymer electrolyte membrane with the highest conductivity samples at various temperature.

  16. Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers

    NASA Astrophysics Data System (ADS)

    Tsuji, Hideto; Noda, Soma; Kimura, Takayuki; Sobue, Tadashi; Arakawa, Yuki

    2017-03-01

    D-configured poly(D-lactic acid) (D-PLA) and poly(D-2-hydroxy-3-methylbutanoic acid) (D-P2H3MB) crystallized separately into their homo-crystallites when crystallized by precipitation or solvent evaporation, whereas incorporation of L-configured poly(L-2-hydroxybutanoic acid) (L-P2HB) in D-configured D-PLA and D-P2H3MB induced co-crystallization or ternary stereocomplex formation between D-configured D-PLA and D-P2H3MB and L-configured L-P2HB. However, incorporation of D-configured poly(D-2-hydroxybutanoic acid) (D-P2HB) in D-configured D-PLA and D-P2H3MB did not cause co-crystallization between D-configured D-PLA and D-P2H3MB and D-configured D-P2HB but separate crystallization of each polymer occurred. These findings strongly suggest that an optically active polymer (L-configured or D-configured polymer) like unsubstituted or substituted optically active poly(lactic acid)s can act as “a configurational or helical molecular glue” for two oppositely configured optically active polymers (two D-configured polymers or two L-configured polymers) to allow their co-crystallization. The increased degree of freedom in polymer combination is expected to assist to pave the way for designing polymeric composites having a wide variety of physical properties, biodegradation rate and behavior in the case of biodegradable polymers.

  17. Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers.

    PubMed

    Tsuji, Hideto; Noda, Soma; Kimura, Takayuki; Sobue, Tadashi; Arakawa, Yuki

    2017-03-24

    D-configured poly(D-lactic acid) (D-PLA) and poly(D-2-hydroxy-3-methylbutanoic acid) (D-P2H3MB) crystallized separately into their homo-crystallites when crystallized by precipitation or solvent evaporation, whereas incorporation of L-configured poly(L-2-hydroxybutanoic acid) (L-P2HB) in D-configured D-PLA and D-P2H3MB induced co-crystallization or ternary stereocomplex formation between D-configured D-PLA and D-P2H3MB and L-configured L-P2HB. However, incorporation of D-configured poly(D-2-hydroxybutanoic acid) (D-P2HB) in D-configured D-PLA and D-P2H3MB did not cause co-crystallization between D-configured D-PLA and D-P2H3MB and D-configured D-P2HB but separate crystallization of each polymer occurred. These findings strongly suggest that an optically active polymer (L-configured or D-configured polymer) like unsubstituted or substituted optically active poly(lactic acid)s can act as "a configurational or helical molecular glue" for two oppositely configured optically active polymers (two D-configured polymers or two L-configured polymers) to allow their co-crystallization. The increased degree of freedom in polymer combination is expected to assist to pave the way for designing polymeric composites having a wide variety of physical properties, biodegradation rate and behavior in the case of biodegradable polymers.

  18. Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers

    PubMed Central

    Tsuji, Hideto; Noda, Soma; Kimura, Takayuki; Sobue, Tadashi; Arakawa, Yuki

    2017-01-01

    D-configured poly(D-lactic acid) (D-PLA) and poly(D-2-hydroxy-3-methylbutanoic acid) (D-P2H3MB) crystallized separately into their homo-crystallites when crystallized by precipitation or solvent evaporation, whereas incorporation of L-configured poly(L-2-hydroxybutanoic acid) (L-P2HB) in D-configured D-PLA and D-P2H3MB induced co-crystallization or ternary stereocomplex formation between D-configured D-PLA and D-P2H3MB and L-configured L-P2HB. However, incorporation of D-configured poly(D-2-hydroxybutanoic acid) (D-P2HB) in D-configured D-PLA and D-P2H3MB did not cause co-crystallization between D-configured D-PLA and D-P2H3MB and D-configured D-P2HB but separate crystallization of each polymer occurred. These findings strongly suggest that an optically active polymer (L-configured or D-configured polymer) like unsubstituted or substituted optically active poly(lactic acid)s can act as “a configurational or helical molecular glue” for two oppositely configured optically active polymers (two D-configured polymers or two L-configured polymers) to allow their co-crystallization. The increased degree of freedom in polymer combination is expected to assist to pave the way for designing polymeric composites having a wide variety of physical properties, biodegradation rate and behavior in the case of biodegradable polymers. PMID:28338051

  19. Poly(lactic acid) and Osage Orange Wood Fiber Composites for Agricultural Mulch Films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Osage orange wood(OO)was combined with poly(lactic acid)(PLA)to form a polymer composite intended for use as an agricultural mulch film. The PLA-OO mechanical properties were comparable to existing mulch film products and had the advantage of being completely biodegradable through a single growing ...

  20. A CRADLE TO GATE LIFE CYCLE ANALYSIS OF THE BIOPOLYMER POLYLACTIC ACID: LOOKING BEYOND GLOBAL WARMING AND FOSSIL FUEL USE

    EPA Science Inventory

    Derived from corn, the biopolymer polylactic acid (PLA) has recently emerged in the marketplace and is advertised as a sustainable alternative to petroleum-based polymers. Research into the environmental implications of biobased production has focused primarily on global warming...

  1. Alkenyl Carboxylic Acid: Engineering the Nanomorphology in Polymer-Polymer Solar Cells as Solvent Additive.

    PubMed

    Zhang, Yannan; Yuan, Jianyu; Sun, Jianxia; Ding, Guanqun; Han, Lu; Ling, Xufeng; Ma, Wanli

    2017-04-06

    We have investigated a series of commercially available alkenyl carboxylic acids with different alkenyl chain lengths (trans-2-hexenoic acid (CA-6), trans-2-decenoic acid (CA-10), 9-tetradecenoic acid (CA-14)) for use as solvent additives in polymer-polymer non-fullerene solar cells. We systematically investigated their effect on the film absorption, morphology, carrier generation, transport, and recombination in all-polymer solar cells. We revealed that these additives have a significant impact on the aggregation of polymer acceptor, leading to improved phase segregation in the blend film. This in-depth understanding of the additives effect on the nanomorphology in all-polymer solar cell can help further boost the device performance. By using CA-10 with the optimal alkenyl chain length, we achieved fine phase separation, balanced charge transport, and suppressed recombination in all-polymer solar cells. As a result, an optimal power conversion efficiency (PCE) of 5.71% was demonstrated which is over 50% higher than that of the as-cast device (PCE = 3.71%) and slightly higher than that of devices with DIO treatment (PCE = 5.68%). Compared with widely used DIO, these halogen-free alkenyl carboxylic acids have a more sustainable processing as well as better performance, which may make them more promising candidates for use as processing additives in organic non-fullerene solar cells.

  2. Crystallization kinetics of poly-(lactic acid) with and without talc: Optical microscopy and calorimetric analysis

    NASA Astrophysics Data System (ADS)

    Refaa, Z.; Boutaous, M.; Rousset, F.; Fulchiron, R.; Zinet, M.; Xin, S.; Bourgin, P.

    2014-05-01

    Poly-(lactic acid) or PLA is a biodegradable polymer synthesized from renewable resources. Recently, the discovery of new polymerization routes has allowed increasing the produced volumes. As a consequence, PLA is becoming of great interest for reducing the dependence on petroleum-based plastics. Because of its interesting mechanical properties, PLA is seen as a potential substitute for some usual polymers. However, its relatively slow crystallization kinetics can be a disadvantage with regard to industrial applications. The crystallization kinetics of PLA can be enhanced by adding nucleating agents, which also influences on crystalline morphology and rheological behavior. In the present work, the isothermal quiescent crystallization kinetics of both neat PLA and PLA/talc composite (5 wt% talc) are investigated. The effects of talc on the overall crystallization kinetics and on the crystalline morphology are analyzed using both optical microscopy measurements and thermal analysis by differential scanning calorimetry.

  3. Stabilization of Resveratrol in Blood Circulation by Conjugation to mPEG and mPEG-PLA Polymers: Investigation of Conjugate Linker and Polymer Composition on Stability, Metabolism, Antioxidant Activity and Pharmacokinetic Profile

    PubMed Central

    Siddalingappa, Basavaraj; Benson, Heather A. E.; Brown, David H.; Batty, Kevin T.; Chen, Yan

    2015-01-01

    Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol. PMID:25799413

  4. Stabilization of resveratrol in blood circulation by conjugation to mPEG and mPEG-PLA polymers: investigation of conjugate linker and polymer composition on stability, metabolism, antioxidant activity and pharmacokinetic profile.

    PubMed

    Siddalingappa, Basavaraj; Benson, Heather A E; Brown, David H; Batty, Kevin T; Chen, Yan

    2015-01-01

    Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol.

  5. Polylactic acid composites incorporating casein functionalized cellulose nanowhiskers

    PubMed Central

    2013-01-01

    Background Polylactic acid (PLA) is considered to be a sustainable alternative to petroleum-based polymers for many applications. Using cellulose fiber to reinforce PLA is of great interest recently due to its complete biodegradability and potential improvement of the mechanical performance. However, the dispersion of hydrophilic cellulose fibers in the hydrophobic polymer matrix is usually poor without using hazardous surfactants. The goal of this study was to develop homogenously dispersed cellulose nanowhisker (CNW) reinforced PLA composites using whole milk casein protein, which is an environmentally compatible dispersant. Results In this study, whole milk casein was chosen as a dispersant in the PLA-CNW system because of its potential to interact with the PLA matrix and cellulose. The affinity of casein to PLA was studied by surface plasmon resonance (SPR) imaging. CNWs were functionalized with casein and used as reinforcements to make PLA composites. Fluorescent staining of CNWs in the PLA matrix was implemented as a novel and simple way to analyze the dispersion of the reinforcements. The dispersion of CNWs in PLA was improved when casein was present. The mechanical properties of the composites were studied experimentally. Compared to pure PLA, the PLA composites had higher Young’s modulus. Casein (CS) functionalized CNW reinforced PLA (PLA-CS-CNW) at 2 wt% filler content maintained higher strain at break compared to normal CNW reinforced PLA (PLA-CNW). The Young’s modulus of PLA-CS-CNW composites was also higher than that of PLA-CNW composites at higher filler content. However, all composites exhibited lower strain at break and tensile strength at high filler content. Conclusions The presence of whole milk casein improved the dispersion of CNWs in the PLA matrix. The improved dispersion of CNWs provided higher modulus of the PLA composites at higher reinforcement loading and maintained the strain and stress at break of the composites at relatively low

  6. Hyperbranched amphiphilic polymer with folate mediated targeting property.

    PubMed

    Zhang, Lei; Hu, Chao-Hua; Cheng, Si-Xue; Zhuo, Ren-Xi

    2010-09-01

    Hyperbranched amphiphilic polymer PG6-PLA-PEG was synthesized through grafting hydrophobic poly(D,L-lactide) (PLA) segments and hydrophilic poly(ethylene glycol) (PEG) blocks to hydrophilic hyperbranched polyglycerol core (PG6), subsequently. To achieve cell targeting property, folic acid (FA) was further incorporated to the hyperbranched polymer to obtain PG6-PLA-PEG-FA. The polymers were characterized by (1)H NMR, UV-vis spectroscopy and combined size-exclusion chromatography and multiangle laser light scattering (SEC-MALLS) analysis. Due to the amphiphilicity, PG6-PLA-PEG and PG6-PLA-PEG-FA could self-assemble to form nanoparticles in aqueous solutions. Antineoplastic drug, paclitaxel (PTX), was encapsulated into the nanoparticles. The nanoparticles were observed by transmission electron microscopy (TEM). The targeting property of PG6-PLA-PEG-FA was evaluated in vitro. The results showed that the PTX loaded PG6-PLA-PEG-FA nanoparticles exhibited enhanced inhibition on folate receptor positive tumor cells due to the folate mediated targeting.

  7. Synthesis of polyacrylic-acid-based thermochromic polymers

    NASA Astrophysics Data System (ADS)

    Srivastava, Jyoti; Alam, Sarfaraz; Mathur, G. N.

    2003-10-01

    Smart materials respond to environmental stimuli with particular changes in some variables (for example temperature, pressure and electric field etc), for that reason they are often called responsive materials. In the present work, we have synthesized thermochromic polymer based on poly acrylic acid cobalt chloride (CoCl2) and phosphoric acid (H3PO4) that visually and reversibly changes color in the temperature range (70 - 130°C). These thermochromic materials can be used as visual sensors of temperature. Thermochromic polymers are based on polyacrylic acid and CoCl2 complex.

  8. 76 FR 7703 - 1,4-Benzenedicarboxylic Acid, Dimethyl Ester, Polymer With 1,4-Butanediol, Adipic Acid, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-11

    ... AGENCY 40 CFR Part 180 1,4-Benzenedicarboxylic Acid, Dimethyl Ester, Polymer With 1,4- Butanediol, Adipic..., polymer with 1,4-butanediol, adipic acid, and hexamethylene diisocyanate (CAS Reg. No. 55231-08-8... residues of 1,4-benzenedicarboxylic acid, dimethyl ester, polymer with 1,4-butanediol, adipic acid,...

  9. Augmentation of a Microbial Consortium for Enhanced Polylactide (PLA) Degradation.

    PubMed

    Nair, Nimisha R; Sekhar, Vini C; Nampoothiri, K Madhavan

    2016-03-01

    Bioplastics are eco-friendly and derived from renewable biomass sources. Innovation in recycling methods will tackle some of the critical issues facing the acceptance of bioplastics. Polylactic acid (PLA) is the commonly used and well-studied bioplastic that is presumed to be biodegradable. Considering their demand and use in near future, exploration for microbes capable of bioplastic degradation has high potential. Four PLA degrading strains were isolated and identified as Penicillium chrysogenum, Cladosporium sphaerospermum, Serratia marcescens and Rhodotorula mucilaginosa. A consortium of above strains degraded 44 % (w/w) PLA in 30 days time in laboratory conditions. Subsequently, the microbial consortium employed effectively for PLA composting.

  10. Biological nitrate removal using wheat straw and PLA as substrate.

    PubMed

    Fan, Zhenxing; Hu, Jun; Wang, Jianlong

    2012-01-01

    Biological nitrate removal using wheat straw and polylactic acid (PLA) as both carbon source and biofilm support was investigated. The results showed that biofilm could develop on the surface of wheat straw within 15 d, the denitrification rate was 0.067 mg-N/(g-wheat straw x h) and nitrate removal efficiency was about 100%. For PLA, the time required for biofilm development was 40 d, the denitrification rate was 0.0026 mg-N/(g-PLA x h) and nitrate removal efficiency could also reach 100%. Temperature had a substantial influence on the denitrification performance of both wheat straw and PLA. The FTIR analysis and SEM observation confirmed that wheat straw and PLA were used for denitrification, and explained some reasons for the differences between the two substrates. The wheat straw was superior to PLA when used as carbon source for nitrate removal, in terms of the denitrification rate.

  11. Synthesis and wound healing of alternating block polyurethanes based on poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG).

    PubMed

    Li, Linjing; Liu, Xiangyu; Niu, Yuqing; Ye, Jianfu; Huang, Shuiwen; Liu, Chao; Xu, Kaitian

    2016-04-05

    Alternating block polyurethanes (abbreviated as PULA-alt-PEG) and random block polyurethanes (abbreviated as PULA-ran-PEG) based on biodegradable poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were prepared. Results showed that alternating block polyurethane gives higher crystal degree, higher mechanical properties, more patterned and rougher surface than the random counterpart, due to the regular and controlled structure. Water absorptions of the polyurethanes were in the range of 620 to 780%. Cytocompatibility of the amphiphilic block polyurethanes (PU) (water static angle 41.4°-61.8°) was assessed by CCK-8 assay using human embryonic kidney (HEK293) cells. Wound healing evaluation of the PU foam scaffolds was carried out by full-thickness SD rat model experiment, with medical gauze as control. It was found that the skin of rat in PU groups was fully covered with new epithelium without any significant adverse reactions and PU dressings give much rapid and better healing than medical gauze. Histological examination revealed that PU dressings suppress the infiltration of inflammatory cells and accelerate fibroblast proliferation. It was also demonstrated that PULA-alt-PEG exhibits obvious better healing effect than PULA-ran-PEG does. This study has demonstrated that without further modification, plain alternating block polyurethane scaffold would help wound recovery efficiently. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  12. Interaction between a high purity magnesium surface and PCL and PLA coatings during dynamic degradation.

    PubMed

    Chen, Ying; Song, Yang; Zhang, Shaoxiang; Li, Jianan; Zhao, Changli; Zhang, Xiaonong

    2011-04-01

    In this study, polycaprolactone (PCL) and polylactic acid (PLA) coatings were prepared on the surface of high purity magnesium (HPMs), respectively, and electrochemical and dynamic degradation tests were used to investigate the degradation behaviors of these polymer-coated HPMs. The experimental results indicated that two uniform and smooth polymer films with thicknesses between 15 and 20 µm were successfully prepared on the HPMs. Electrochemical tests showed that both PCL-coated and PLA-coated HPMs had higher free corrosion potentials (E(corr)) and smaller corrosion currents (I(corr)) in the modified simulated body fluid (m-SBF) at 37 °C, compared to those of the uncoated HPMs. Dynamic degradation tests simulating the flow conditions in coronary arteries were carried out on a specific test platform. The weight of the specimens and the pH over the tests were recorded to characterize the corrosion performance of those samples. The surfaces of the specimens after the dynamic degradation tests were also examined. The data implied that there was a special interaction between HPM and its polymer coatings during the dynamic degradation tests, which undermined the corrosion resistance of the coated HPMs. A model was proposed to illustrate the interaction between the polymer coatings and HPM. This study also suggested that this reciprocity may also exist on the implanted magnesium stents coated with biodegradable polymers, which is a potential obstacle for the further development of drug-eluting magnesium stents.

  13. Nanocrystalline nickel ferrite particles synthesized by non-hydrolytic sol-gel method and their composite with biodegradable polymer.

    PubMed

    Yin, H; Casey, P S; Chow, G M

    2012-11-01

    Targeted drug delivery has been one of the most important biomedical applications for magnetic particles. Such applications require magnetic particles to have functionalized surfaces/surface coatings that facilitate their incorporation into a polymer matrix to produce a polymer composite. In this paper, nanocrystalline nickel ferrite particles with an oleic acid surface coating were synthesized using a non-hydrolytic sol-gel method and incorporated into a biodegradable polymer matrix, poly(D,L-lactide) PLA prepared using a double emulsion method. As-synthesized nickel ferrite particles had a multi-crystalline structure with chemically adsorbed oleic acid on their surface. After forming the PLA composite, nickel ferrite particles were encapsulated in PLA microspheres. At low nickel ferrite concentrations, composites showed very similar surface charges to that of PLA. The composites were magnetically responsive and increasing the nickel ferrite concentration was found to increase magnetization of the composite.

  14. An amphiphilic degradable polymer/hydroxyapatite composite with enhanced handling characteristics promotes osteogenic gene expression in bone marrow stromal cells.

    PubMed

    Kutikov, Artem B; Song, Jie

    2013-09-01

    Electrospun polymer/hydroxyapatite (HA) composites combining biodegradability with osteoconductivity are attractive for skeletal tissue engineering applications. However, most biodegradable polymers such as poly(lactic acid) (PLA) are hydrophobic and do not blend with adequate interfacial adhesion with HA, compromising the structural homogeneity, mechanical integrity and biological performance of the composite. To overcome this challenge, we combined a hydrophilic polyethylene glycol (PEG) block with poly(d,l-lactic acid) to improve the adhesion of the degradable polymer with HA. The amphiphilic triblock copolymer PLA-PEG-PLA (PELA) improved the stability of HA-PELA suspension at 25wt.% HA content, which was readily electrospun into HA-PELA composite scaffolds with uniform fiber dimensions. HA-PELA was highly extensible (failure strain>200% vs. <40% for HA-PLA), superhydrophilic (∼0° water contact angle vs. >100° for HA-PLA), and exhibited an 8-fold storage modulus increase (unlike deterioration for HA-PLA) upon hydration, owing to the favorable interaction between HA and PEG. HA-PELA also better promoted osteochondral lineage commitment of bone marrow stromal cells in unstimulated culture and supported far more potent osteogenic gene expression upon induction than HA-PLA. We demonstrate that the chemical incorporation of PEG is an effective strategy to improve the performance of degradable polymer/HA composites for bone tissue engineering applications.

  15. Electrospun PLA: PCL composites embedded with unmodified and 3-aminopropyltriethoxysilane (ASP) modified halloysite nanotubes (HNT)

    NASA Astrophysics Data System (ADS)

    Haroosh, Hazim J.; Dong, Yu; Chaudhary, Deeptangshu S.; Ingram, Gordon D.; Yusa, Shin-ichi

    2013-02-01

    Electrospinning is a simple and versatile fiber synthesis technique in which a high-voltage electric field is applied to a stream of polymer melt or polymer solution, resulting in the formation of continuous micro/nanofibers. Halloysite nanotubes (HNT) have been found to achieve improved structural and mechanical properties when embedded into various polymer matrices. This research work focuses on blending poly( ɛ-caprolactone) (PCL) (9 and 15 wt%/v) and poly(lactic acid) (PLA) (fixed at 8 wt%/v) solutions with HNT at two different concentrations 1 and 2 wt%/v. Both unmodified HNT and HNT modified with 3-aminopropyltriethoxysilane (ASP) were utilized in this study. Fiber properties have been shown to be strongly related to the solution viscosity and electrical conductivity. The addition of HNT increased the solution viscosity, thus resulting in the production of uniform fibers. For both PCL concentrations, the average fiber diameter increased with the increasing of HNT concentration. The average fiber diameters with HNT-ASP were reduced considerably in comparison to those with unmodified HNT when using 15 wt%/v PCL. Slightly better dispersion was obtained for PLA: PCL composites embedded with HNT-ASP compared to unmodified HNT. Furthermore, the addition of HNT-ASP to the polymeric blends resulted in a moderate decrease in the degree of crystallinity, as well as slight reductions of glass transition temperature of PCL, the crystallization temperature and melting temperature of PLA within composite materials. The infrared spectra of composites confirmed the successful embedding of HNT-ASP into PLA: PCL nanofibers relative to unmodified HNT due to the premodification using ASP to reduce the agglomeration behavior. This study provides a new material system that could be potentially used in drug delivery, and may facilitate good control of the drug release process.

  16. Production of PLA-Starch Fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composites of polylactic acid (PLA) with starch have been prepared previously in an effort to reduce cost as well as to modify other properties such as biodegradation rate. However, strength and elongation both decrease on addition of starch due to poor adhesion and stress concentration at the inte...

  17. Fabrication and surface modification of poly lactic acid (PLA) scaffolds with epidermal growth factor for neural tissue engineering

    PubMed Central

    Haddad, Tanit; Noel, Samantha; Liberelle, Benoît; El Ayoubi, Rouwayda; Ajji, Abdellah

    2016-01-01

    ABSTRACT In an effort to design biomaterials that may promote repair of the central nervous system, 3-dimensional scaffolds made of electrospun poly lactic acid nanofibers with interconnected pores were fabricated. These scaffolds were functionalized with polyallylamine to introduce amine groups by wet chemistry. Experimental conditions of the amination protocol were thoroughly studied and selected to introduce a high amount of amine group while preserving the mechanical and structural properties of the scaffold. Subsequent covalent grafting of epidermal growth factor was then performed to further tailor these aminated structures. The scaffolds were then tested for their ability to support Neural Stem-Like Cells (NSLCs) culture. Of interest, NSLCs were able to proliferate on these EGF-grafted substrates and remained viable up to 14 d even in the absence of soluble growth factors in the medium. PMID:27740881

  18. An investigation of crystallization and rheological behaviors of PLA/HDPE/Nano-CaCO3 composites by experimental design

    NASA Astrophysics Data System (ADS)

    de Oliveira, Amanda G.; Teixeira, Viviane G.; da Silva, Ana Lúcia N.; de Sousa, Ana Maria F.

    2015-05-01

    Nowadays, the development of products from renewable raw material has been an important subject of interest for a great number of researchers. Poly(lactic acid) is versatile polymer, synthesized from renewable resources, biodegradable and biocompatible and that has been considered as stronger candidate to replace fossil-based polymers in many application. However, the PLA still has some shortcomings to be solved, such as low thermal resistance, rate crystallization, impact resistance and gas barrier properties. Thus, adding nanofiller can be an interesting method to extend and to improve the PLA properties. The aim of this work is to evaluate the rheological and thermal properties of composites based on PLA/nano-CaCO3/HDPE by using a design of experiments (DOE)-2n Factorial, with three center points. Three factors were studied: HDPE/nano-CaCO3 masterbatch content, temperature and mixer speed. All PLA/Nano-CaCO3/HDPE experiments were characterized by differential scanning calorimetry (DSC), torque rheometry and melt flow index analysis (MFI). It was noticed that torque rheometry was affected by the addition of the HDPE/nano-CaCO3 masterbatch content and it was also observed a synergism among the factors. The nanofiller content, added in the masterbatch, also affected the flow behavior of composites produced.

  19. Facile synthesis of nucleic acid-polymer amphiphiles and their self-assembly.

    PubMed

    Jia, Fei; Lu, Xueguang; Tan, Xuyu; Zhang, Ke

    2015-05-07

    A solid-phase synthesis for nucleic acid-polymer amphiphiles is developed. Using this strategy, several DNA-b-polymer amphiphiles are synthesized, and their self-assembly in aqueous solution is investigated. This general method can in principle be extended to nearly all polymers synthesized by atom transfer radical polymerization to produce a variety of nucleic acid-polymer conjugates.

  20. Behaviors of keratinocytes and fibroblasts on films of PLA50-PEO-PLA50 triblock copolymers with various PLA segment lengths.

    PubMed

    Garric, Xavier; Garreau, Henri; Vert, Michel; Molès, Jean-Pierre

    2008-04-01

    The growth of human primary keratinocytes and fibroblasts on PLA-PEO-PLA copolymer films was investigated as an intermediate stage of a strategy aimed at making implantable dermo-epidermal substitutes. Four PLA-PEO-PLA triblock copolymers with the same PEO block and different DL-lactic acid/ethylene oxide molar ratios (LA/EO) (0.8, 1.4, 1.8 and 2), were synthesized and characterized by 1H-nuclear magnetic resonance and infrared spectroscopy. The films made of these copolymers were more hydrophilic than PLA50 and than tissue culture polystyrene controls according to contact angles with water. Proliferation and adhesion of human skin cells were evaluated by MTT assay and by scanning electron microscopy. The presence of PEO in the triblock copolymers influenced cell adhesion and proliferation of fibroblasts, whereas keratinocyte adhesion and proliferation were not affected. These features emphasize the interest of PLA-PEO-PLA triblock copolymers to serve as better compounds than the racemic PLA previously investigated to make supports for human skin primary cells and scaffolds for skin engineering.

  1. Design of PEG-grafted-PLA nanoparticles as oral permeability enhancer for P-gp substrate drug model Famotidine.

    PubMed

    Mokhtar, Mohamed; Gosselin, Patrick M; Lacasse, François; Hildgen, Patrice

    2017-02-02

    Bioavailability of oral drugs can be limited by an intestinal excretion process mediated by P-glycoprotein (P-gp). Polyethylene glycol (PEG) is a known P-gp inhibitor. Dispersion of Famotidine (a P-gp substrate) within PEGylated nanoparticles (NPs) was used to improve its oral bioavailability. In this work, we evaluated the potential impact of NPs prepared from a grafted copolymer of polylactic acid and PEG on P-gp function by studying in vitro permeability of Famotidine across Caco-2 cells. Copolymers of PEG grafted on polylactic acid a (PLA) backbone (PLA-g-PEG) were synthesized with 1 mol% and 5 mol% PEG vs. lactic acid monomer using PEG 750 and 2000 Da. The polymers were used to prepare Famotidine-loaded NPs and tested in vitro on Caco-2 cells. Significant decrease in basolateral-to-apical transport of Famotidine was observed when Famotidine was encapsulated in NPs prepared from PLA-g-PEG5%. NPs prepared from PLA-g-PEG5% are promising to improve oral bioavailability of P-gp substrates.

  2. Crosslinked carboxymethylchitosan-g-poly(acrylic acid) copolymer as a novel superabsorbent polymer.

    PubMed

    Chen, Yu; Tan, Hui-min

    2006-05-22

    A novel carboxymethylchitosan-g-poly(acrylic acid) (CMCTS-g-PAA) superabsorbent polymer was prepared through graft polymerization of acrylic acid onto the chain of carboxymethylchitosan and subsequent crosslinking. It was demonstrated by FTIR spectroscopy that acrylic acid had been graft polymerized with carboxymethylchitosan. The thermal stability of the polymer was characterized by thermogravimetric analysis. By studying the swelling ratio of the polymer synthesized under different conditions, optimization conditions were found for a polymer with the highest swelling ratio. The rate of water absorption of the polymer was high, and the swelling of the polymer fitted the process of first dynamics. The swelling ratio of the polymer was pH-dependent.

  3. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, P.V.; Coleman, R.D.

    1996-10-08

    A water and UV light degradable copolymer is described made from monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  4. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, Patrick V.; Coleman, Robert D.

    1996-01-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  5. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, Patrick V.; Coleman, Robert D.

    1994-01-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene and polyethylene glycols, propylene and polypropylene glycols, P-dioxanone, 1,5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  6. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, P.V.; Coleman, R.D.

    1994-11-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer were selected from the class consisting of ethylene and polyethylene glycols, propylene and polypropylene glycols, P-dioxanone, 1,5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide where the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures to an agricultural site is also disclosed.

  7. Water and UV degradable lactic acid polymers

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.

    1990-06-26

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene and polyethylane glycols (PVB 6/22/90), propylene and and polypropylene (PVB 6/22/90) glycols, P-dioxanone, 1, 5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  8. 40 CFR 721.6560 - Acrylic acid, polymer with substituted ethene.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.6560 Acrylic acid, polymer with substituted ethene. (a) Chemical... as acrylic acid, polymer with substituted ethene (PMN P-91-521) is subject to reporting under...

  9. 40 CFR 721.10032 - Acrylic acid, polymer with substituted acrylamides (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.10032 Acrylic acid, polymer with substituted acrylamides (generic). (a... generically as acrylic acid, polymer with substituted acrylamides (PMN P-02-269) is subject to reporting...

  10. 40 CFR 721.6560 - Acrylic acid, polymer with substituted ethene.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.6560 Acrylic acid, polymer with substituted ethene. (a) Chemical... as acrylic acid, polymer with substituted ethene (PMN P-91-521) is subject to reporting under...

  11. 75 FR 52269 - Acetic Acid Ethenyl Ester, Polymer With Oxirane; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-25

    ...-2010-0429; FRL-8841-2] Acetic Acid Ethenyl Ester, Polymer With Oxirane; Tolerance Exemption AGENCY... from the requirement of a tolerance for residues of acetic acid ethenyl ester, polymer with oxirane... permissible level for residues of acetic acid ethenyl ester, polymer with oxirane on food or feed...

  12. 75 FR 31713 - 2-Propenoic acid polymer, with 1,3-butadiene and ethenylbenzene; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-04

    ... AGENCY 40 CFR Part 180 2-Propenoic acid polymer, with 1,3-butadiene and ethenylbenzene; Tolerance... establishes an exemption from the requirement of a tolerance for residues of 2-propenoic acid polymer, with 1... a maximum permissible level for residues of 2-propenoic acid polymer, with 1,3-butadiene...

  13. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer...

  14. 40 CFR 721.6560 - Acrylic acid, polymer with substituted ethene.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.6560 Acrylic acid, polymer with substituted ethene. (a) Chemical... as acrylic acid, polymer with substituted ethene (PMN P-91-521) is subject to reporting under...

  15. 40 CFR 721.10032 - Acrylic acid, polymer with substituted acrylamides (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.10032 Acrylic acid, polymer with substituted acrylamides (generic). (a... generically as acrylic acid, polymer with substituted acrylamides (PMN P-02-269) is subject to reporting...

  16. 40 CFR 721.6560 - Acrylic acid, polymer with substituted ethene.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.6560 Acrylic acid, polymer with substituted ethene. (a) Chemical... as acrylic acid, polymer with substituted ethene (PMN P-91-521) is subject to reporting under...

  17. 40 CFR 721.10032 - Acrylic acid, polymer with substituted acrylamides (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.10032 Acrylic acid, polymer with substituted acrylamides (generic). (a... generically as acrylic acid, polymer with substituted acrylamides (PMN P-02-269) is subject to reporting...

  18. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer...

  19. 40 CFR 721.10032 - Acrylic acid, polymer with substituted acrylamides (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.10032 Acrylic acid, polymer with substituted acrylamides (generic). (a... generically as acrylic acid, polymer with substituted acrylamides (PMN P-02-269) is subject to reporting...

  20. 40 CFR 721.6560 - Acrylic acid, polymer with substituted ethene.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.6560 Acrylic acid, polymer with substituted ethene. (a) Chemical... as acrylic acid, polymer with substituted ethene (PMN P-91-521) is subject to reporting under...

  1. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer...

  2. 40 CFR 721.10032 - Acrylic acid, polymer with substituted acrylamides (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Acrylic acid, polymer with substituted... Specific Chemical Substances § 721.10032 Acrylic acid, polymer with substituted acrylamides (generic). (a... generically as acrylic acid, polymer with substituted acrylamides (PMN P-02-269) is subject to reporting...

  3. 40 CFR 721.10220 - Phosphoric acid, polymer with cycloaliphatic diglycidyl ether, alkylethers (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Phosphoric acid, polymer with... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10220 Phosphoric acid, polymer with... to reporting. (1) The chemical substance identified generically as phosphoric acid, polymer...

  4. Development of polylactide (PLA) and PLA nanocomposite foams in injection molding for automotive applications

    NASA Astrophysics Data System (ADS)

    Najafi Chaloupli, Naqi

    Plastic materials are extensively used in automotive structures since they make cars more energy efficient. Recently, the automotive industry is searching for bio-based and renewable alternatives to petroleum-based plastics to reduce the dependence on fossil fuels. Among polymers originating from renewable sources, polylactide (PLA) has attracted significant interest. The use of this polymer in durable industries is promising. Fuel-efficient automobiles are nowadays demanded due to the increasing concerns about environmental and fuel issues. The automobile fuel efficiency can be improved by using a lightweight material and, thereby, reducing the automobile weight. A potential method to achieve this objective is the use of the foaming technology. Foam is a material where a gas phase is encapsulated by a solid phase. Foaming technology helps to manufacture lightweight parts with superior properties in comparison with their solid counterparts. The basic mechanisms of foaming process normally consists of gas implementation, formation of uniform polymer-gas solution, cell nucleation, cell growth and, finally, cell stabilization. PLA foaming has, however, proved to be difficult mainly due to poor rheological properties, small processing window, and slow crystallization kinetics. The ultimate purpose of this work is to reduce by 30 % the weight of polylactide (PLA)-clay based nanocomposites by manufacturing injection-molded foamed parts. To use standard processing equipment, a chemical blowing agent (CBA) was employed. The injection molding technique was utilized in this project because it is the most widely used fabrication process in industry that can produce complex shaped articles. This process, however, is more challenging than other foaming processes since it deals with many additional controlling parameters. In the first part of this project, we illustrated how long chain branching (LCB) and molecular structure impact the melt rheology, crystallization and batch

  5. Polymers with complexing properties. Simple poly(amino acids)

    NASA Technical Reports Server (NTRS)

    Roque, J. M.

    1978-01-01

    The free amino (0.3 equiv/residue) and carboxyl (0.5 equiv/residue) groups of thermal polylysine increased dramatically on treatment with distilled water. The total hydrolysis of such a polymer was abnormal in that only about 50% of the expected amino acids were recovered. Poly (lysine-co-alanine-co-glycine) under usual conditions hydrolyzed completely in 8 hours; whereas, when it was pretreated with diazomethane, a normal period of 24 hours was required to give (nearly) the same amounts of each free amino acid as compared with those obtained from the untreated polymer. The amino groups of the basic thermal poly(amino acids) were sterically hindered. The existence of nitrogen atoms linking two or three chains and reactive groups (anhydride, imine) were proposed.

  6. Poly(dopamine) coating of 3D printed poly(lactic acid) scaffolds for bone tissue engineering.

    PubMed

    Kao, Chia-Tze; Lin, Chi-Chang; Chen, Yi-Wen; Yeh, Chia-Hung; Fang, Hsin-Yuan; Shie, Ming-You

    2015-11-01

    3D printing is a versatile technique to generate large quantities of a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized 3D printed poly(lactic acid) (PLA) scaffolds and use a mussel-inspired surface coating to regulate cell adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared PLA 3D scaffolds coated with polydopamine (PDA). The chemical composition and surface properties of PDA/PLA were characterized by XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation, and cell cycle of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. In addition, the collagen I secreted from cells was increased and promoted cell attachment and cell cycle progression were depended on the PDA content. In osteogenesis assay, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on pure PLA scaffolds. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenic differentiation. Our results demonstrate that the bio-inspired coating synthetic PLA polymer can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to direct the specific responses of hADSCs.

  7. Recent advances in PEG-PLA block copolymer nanoparticles.

    PubMed

    Xiao, Ren Zhong; Zeng, Zhao Wu; Zhou, Guang Lin; Wang, Jun Jie; Li, Fan Zhu; Wang, An Ming

    2010-11-26

    Due to their small particle size and large and modifiable surface, nanoparticles have unique advantages compared with other drug carriers. As a research focus in recent years, polyethylene glycol-polylactic acid (PEG-PLA) block copolymer and its end-group derivative nanoparticles can enhance the drug loading of hydrophobic drugs, reduce the burst effect, avoid being engulfed by phagocytes, increase the circulation time of drugs in blood, and improve bioavailability. Additionally, due to their smaller particle size and modified surface, these nanoparticles can accumulate in inflammation or target locations to enhance drug efficacy and reduce toxicity. Recent advances in PEG-PLA block copolymer nanoparticles, including the synthesis of PEG-PLA and the preparation of PEG-PLA nanoparticles, were introduced in this study, in particular the drug release and modifiable characteristics of PEG-PLA nanoparticles and their application in pharmaceutical preparations.

  8. Interaction of humic acids and humic-acid-like polymers with herpes simplex virus type 1

    NASA Astrophysics Data System (ADS)

    Klöcking, Renate; Helbig, Björn

    The study was performed in order to compare the antiviral activity against herpes simplex virus type 1 (HSV-1) of synthetic humic-acid-like polymers to that of their low-molecular-weight basic compounds and naturally occurring humic acids (HA) in vitro. HA from peat water showed a moderate antiviral activity at a minimum effective concentration (MEC) of 20 µg/ml. HA-like polymers, i.e. the oxidation products of caffeic acid (KOP), hydrocaffeic acid (HYKOP), chlorogenic acid (CHOP), 3,4-dihydroxyphenylacetic acid (3,4-DHPOP), nordihydroguaretic acid (NOROP), gentisinic acid (GENOP), pyrogallol (PYROP) and gallic acid (GALOP), generally inhibit virus multiplication, although with different potency and selectivity. Of the substances tested, GENOP, KOP, 3,4-DHPOP and HYKOP with MEC values in the range of 2 to 10 µg/ml, proved to be the most potent HSV-1 inhibitors. Despite its lower antiviral potency (MEC 40 µg/ml), CHOP has a remarkable selectivity due to the high concentration of this polymer that is tolerated by the host cells (>640 µg/ml). As a rule, the antiviral activity of the synthetic compounds was restricted to the polymers and was not preformed in the low-molecular-weight basic compounds. This finding speaks in favour of the formation of antivirally active structures during the oxidative polymerization of phenolic compounds and, indirectly, of corresponding structural parts in different HA-type substances.

  9. Mechanical and thermal properties of polylactic acid composites reinforced with cellulose nanoparticles extracted from kenaf fibre

    NASA Astrophysics Data System (ADS)

    Ketabchi, Mohammad Reza; Khalid, Mohammad; Thevy Ratnam, Chantara; Walvekar, Rashmi

    2016-12-01

    Different approaches have been attempted to use biomass as filler for production of biodegradable polymer composites. In this study, cellulose nanoparticles (CNP) extracted from kenaf fibres were used to produce polylactic acid (PLA) based biodegradable nanocomposites. CNP concentration was varied from 1-5 wt. % and blended with PLA using Brabender twin-screw compounder. Effects of CNP loading on the mechanical, thermal and dynamic properties of PLA were investigated. Studies on the morphological properties and influence of CNP loading on the properties of CNP/PLA nanocomposite were also conducted. The results show an adequate compatibility between CNP and PLA matrix. Moreover, addition of 3 wt. % of CNP improved the PLA tensile strength by 25%.

  10. Development of Micro Lancet Needle Made of Biodegradable Polymer for Medical Treatment

    NASA Astrophysics Data System (ADS)

    Aoyagi, Seiji; Izumi, Hayato; Aoki, Toshiro; Fukuda, Mitsuo

    The aim of this paper is development of micro lancet needle made of biodegradable polymer (Poly Lactic Acid, called as PLA). This device is applicable to a blood test system for diabetics. Since PLA naturally degrades itself in tissues, this material is safe for human body. To achieve the purpose of this study, we focused on wet chemical anisotropic etching process of silicon negative groove, and micromolding process of PLA. Resistance force during inserting a fabricated needle to an artificial skin of silicone rubber is investigated experimentally. The effects of thinning needle, sharpening tip, vibrating it during insertion, pitching out the inserted object surface, etc., for decreasing the resistance force are confirmed.

  11. Polymer gel dosimeter based on itaconic acid.

    PubMed

    Mattea, Facundo; Chacón, David; Vedelago, José; Valente, Mauro; Strumia, Miriam C

    2015-11-01

    A new polymeric dosimeter based on itaconic acid and N, N'-methylenebisacrylamide was studied. The preparation method, compositions of monomer and crosslinking agent and the presence of oxygen in the dosimetric system were analyzed. The resulting materials were irradiated with an X-ray tube at 158cGy/min, 226cGymin and 298cGy/min with doses up to 1000Gy. The dosimeters presented a linear response in the dose range 75-1000Gy, sensitivities of 0.037 1/Gyat 298cGy/min and an increase in the sensitivity with lower dose rates. One of the most relevant outcomes in this study was obtaining different monomer to crosslinker inclusion in the formed gel for the dosimeters where oxygen was purged during the preparation method. This effect has not been reported in other typical dosimeters and could be attributed to the large differences in the reactivity among these species.

  12. Zinc Metalloproteinase ProA Directly Activates Legionella pneumophila PlaC Glycerophospholipid:cholesterol Acyltransferase*

    PubMed Central

    Lang, Christina; Rastew, Elena; Hermes, Björn; Siegbrecht, Enrico; Ahrends, Robert; Banerji, Sangeeta; Flieger, Antje

    2012-01-01

    Enzymes secreted by Legionella pneumophila, such as phospholipases A (PLAs) and glycerophospholipid:cholesterol acyltransferases (GCATs), may target host cell lipids and therefore contribute to the establishment of Legionnaires disease. L. pneumophila possesses three proteins, PlaA, PlaC, and PlaD, belonging to the GDSL family of lipases/acyltransferases. We have shown previously that PlaC is the major GCAT secreted by L. pneumophila and that the zinc metalloproteinase ProA is essential for GCAT activity. Here we characterized the mode of PlaC GCAT activation and determined that ProA directly processes PlaC. We further found that not only cholesterol but also ergosterol present in protozoa was palmitoylated by PlaC. Such ester formations were not induced by either PlaA or PlaD. PlaD was shown here to possess lysophospholipase A activity, and interestingly, all three GDSL enzymes transferred short chain fatty acids to sterols. The three single putative catalytic amino acids (Ser-37, Asp-398, and His-401) proved essential for all PlaC-associated PLA, lysophospholipase A, and GCAT activities. A further four cysteine residues are important for the PLA/GCAT activities as well as their oxidized state, and we therefore conclude that PlaC likely forms at least one disulfide loop. Analysis of cleavage site and loop deletion mutants suggested that for GCAT activation deletion of several amino acids within the loop is necessary rather than cleavage at a single site. Our data therefore suggest a novel enzyme inhibition/activation mechanism where a disulfide loop inhibits PlaC GCAT activity until the protein is exported to the external space where it is ProA-activated. PMID:22582391

  13. Nanoscale mechanical measurement determination of the glass transition temperature of poly(lactic acid)/everolimus coated stents in air and dissolution media.

    PubMed

    Wu, Ming; Kleiner, Lothar; Tang, Fuh-Wei; Hossainy, Syed; Davies, Martyn C; Roberts, Clive J

    2009-03-02

    Localized atomic force microscopy (AFM) force analysis on poly(lactic acid) (PLA) and poly(lactic acid)/everolimus coated stents has been performed under ambient conditions. Similar Young's modulus were derived from both PLA and PLA/everolimus stent surface, namely 2.25+/-0.46 and 2.04+/-0.39GPa, respectively, indicating that the drug, everolimus does not significantly effect the mechanical properties of PLA up to a 1:1 (w/w) drug loading. Temperature controlled force measurements on PLA only coated stents in air and in a 1% Triton surfactant solution allowed the glass transition temperature (T(g)) of the polymer to be determined. A significant drop of the Young's modulus in solution was observed at 36 degrees C, suggests that in vivo the T(g) of the polymer is below body temperature. The possible consequences on drug release and the mechanisms by which this may occur are considered.

  14. sPLA2 IB induces human podocyte apoptosis via the M-type phospholipase A2 receptor.

    PubMed

    Pan, Yangbin; Wan, Jianxin; Liu, Yipeng; Yang, Qian; Liang, Wei; Singhal, Pravin C; Saleem, Moin A; Ding, Guohua

    2014-10-22

    The M-type phospholipase A2 receptor (PLA2R) is expressed in podocytes in human glomeruli. Group IB secretory phospholipase A2 (sPLA2 IB), which is one of the ligands of the PLA2R, is more highly expressed in chronic renal failure patients than in controls. However, the roles of the PLA2R and sPLA2 IB in the pathogenesis of glomerular diseases are unknown. In the present study, we found that more podocyte apoptosis occurs in the kidneys of patients with higher PLA2R and serum sPLA2 IB levels. In vitro, we demonstrated that human podocyte cells expressed the PLA2R in the cell membrane. After binding with the PLA2R, sPLA2 IB induced podocyte apoptosis in a time- and concentration-dependent manner. sPLA2 IB-induced podocyte PLA2R upregulation was not only associated with increased ERK1/2 and cPLA2α phosphorylation but also displayed enhanced apoptosis. In contrast, PLA2R-silenced human podocytes displayed attenuated apoptosis. sPLA2 IB enhanced podocyte arachidonic acid (AA) content in a dose-dependent manner. These data indicate that sPLA2 IB has the potential to induce human podocyte apoptosis via binding to the PLA2R. The sPLA2 IB-PLA2R interaction stimulated podocyte apoptosis through activating ERK1/2 and cPLA2α and through increasing the podocyte AA content.

  15. Acid activation of bentonites and polymer-clay nanocomposites.

    SciTech Connect

    Carrado, K. A.; Komadel, P.; Center for Nanoscale Materials; Slovak Academy of Sciences

    2009-04-01

    Modified bentonites are of widespread technological importance. Common modifications include acid activation and organic treatment. Acid activation has been used for decades to prepare bleaching earths for adsorbing impurities from edible and industrial oils. Organic treatment has sparked an explosive interest in a class of materials called polymer-clay nanocomposites (PCNs). The most commonly used clay mineral in PCNs is montmorillonite, which is the main constituent of bentonite. PCN materials are used for structural reinforcement and mechanical strength, for gas permeability barriers, as flame retardants, and to minimize surface erosion (ablation). Other specialty applications include use as conducting nanocomposites and bionanocomposites.

  16. 76 FR 77709 - Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... AGENCY 40 CFR Part 180 Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption AGENCY... from the requirement of a tolerance for residues of 2-Propenoic acid, 2-methyl-, polymer with butyl 2...-styrene polymer when used as an inert ingredient in a pesticide chemical formulation....

  17. 40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hexanedioic acid polymer with... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject...

  18. 78 FR 70878 - Octadecanoic Acid, 12-Hydroxy-, Homopolymer, Ester With 2-Methyloxirane Polymer With Oxirane...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-27

    ... AGENCY 40 CFR Part 180 Octadecanoic Acid, 12-Hydroxy-, Homopolymer, Ester With 2- Methyloxirane Polymer... residues of Octadecanoic Acid, 12-Hydroxy-, Homopolymer, Ester with 2-Methyloxirane Polymer with Oxirane... 2- Methyloxirane Polymer with Oxirane Monobutyl Ether on food or feed commodities. DATES:...

  19. Comparison of acidic polymers for the removal of cobalt from water solutions by polymer assisted ultrafiltration.

    PubMed

    Dambies, Laurent; Jaworska, Agnieszka; Zakrzewska-Trznadel, Grazyna; Sartowska, Bozena

    2010-06-15

    In this study, three sulfonated water-soluble polymers based on poly(vinyl alcohol) of different molecular weights (10,000, 50,000 and 100,000 Da) were prepared and tested against commercially available poly(acrylic acid) for the removal of cobalt using polymer assisted ultrafiltration. High rejection rates were obtained between pH 3 and 6 with sulfonated poly(vinyl alcohol) (PVA 10,000 and 50,000 Da) whereas poly(acrylic acid) (PAA) of similar molecular weights performed rather poorly in this pH range. Sulfonation improved significantly sorption capability of PVA. Sulfonated PVA 10,000 was the best complexing agent with rejection rate above 95% between pH 3 and 6. For unmodified PVA the rejection rate was only 30-45% at pH 6 and there was no rejection at pH 3 at all. PAA rejection rate was above 90% at pH 6 and only about 10% at pH 3. Large scale experiment in cross-flow, continuous apparatus conducted by using PVA-SO(3)H 10,000 Da to remove (60)Co radioisotope from water solutions showed excellent results demonstrating the potential of this polymer to purify acidic radioactive wastes containing cobalt radioisotopes.

  20. Surface Lewis acid-base properties of polymers measured by inverse gas chromatography.

    PubMed

    Shi, Baoli; Zhang, Qianru; Jia, Lina; Liu, Yang; Li, Bin

    2007-05-18

    Surface Lewis acid-base properties are significant for polymers materials. The acid constant, K(a) and base constant, K(b) of many polymers were characterized by some researchers with inverse gas chromatography (IGC) in recent years. In this paper, the surface acid-base constants, K(a) and K(b) of 20 kinds of polymers measured by IGC in recent years are summarized and discussed, including seven polymers characterized in this work. After plotting K(b) versus K(a), it is found that the polymers can be encircled by a triangle. They scatter in two regions of the triangle. Four polymers exist in region I. K(b)/K(a) of the polymers in region I are 1.4-2.1. The other polymers exist in region II. Most of the polymers are relative basic materials.

  1. Mesenchymal stem cells growth and proliferation enhancement using PLA vs PCL based nanofibrous scaffolds.

    PubMed

    Marei, Narguess H; El-Sherbiny, Ibrahim M; Lotfy, Ahmed; El-Badawy, Ahmed; El-Badri, Nagwa

    2016-12-01

    Electrospinning of polymers is the most commonly used technique for nanofiber fabrication. polylactic acid (PLA) and polycaprolactone (PCL) have been shown to be ideal for nanofiber preparation in various biomedical applications, due to characteristics such as biodegradablity and their ability to promote the cell growth, similar to native tissues. The aim of this study was to develop biocompatible and biodegradable PLA and PCL-based nanofibrous scaffolds for enhancing stem cell growth and proliferation. The scaffolds were prepared by electrospinning, and their physicochemical properties were studied using Fourier Transform Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The surface morphology of the developed scaffolds was determined using scanning electron microscopy (SEM). Mesenchymal stem cells (MSCs), derived from both adipose tissue and bone marrow, were seeded onto the prepared nanofibrous scaffolds. The effect of scaffold type, and structural characteristics on survival and proliferation of MSCs were evaluated. Our results show that after full physicochemical characterization of PCL and PLA nanofibrous scaffolds both were safe and non-toxic to the evaluated cells and both scaffolds supported cell attachment and proliferation of bone marrow and adipose tissue-derived MSCs.

  2. Novel sustainable polymers derived from renewable rosin and fatty acids

    NASA Astrophysics Data System (ADS)

    Wilbon, Perry

    In the work of this dissertation, polymers derived from renewable bio-based resources prepared by various polymerization techniques were investigated. The properties of these polymeric materials were characterized and discussed. Rosin was first converted into acrylate or methacrylate monomers for atom transfer radical polymerization (ATRP). Second, rosin was combined with vegetable oil to produce completely renewable novel polyesters by acyclic diene metathesis (ADMET) polymerization. Third, degradable block copolymers were synthesized composed of polycaprolactone and rosin grafted polycaprolactone with the aid of ring-opening polymerization (ROP). Finally, degradable polyesters were produced using vegetable oil derivatives as starting materials. These new rosin and fatty acid based renewable polymer materials will have potential applications as sustainable thermoplastics, thermoplastic elastomers, etc.

  3. Preactivated hyaluronic acid: A potential mucoadhesive polymer for vaginal delivery.

    PubMed

    Nowak, Jessika; Laffleur, Flavia; Bernkop-Schnürch, Andreas

    2015-01-15

    The objective of this study was to develop mucoadhesive polymeric excipients for vaginal drug delivery systems. Hyaluronic acid was thiolated and subsequently preactivated with 6-mercaptonicotinamide (HA-CYS-MNA) to enhance stability and mucoadhesive properties on vaginal mucosa. After determination of the thiol group content, disintegration studies and in vitro mucoadhesion studies (rotating cylinder and tensile) were performed. Furthermore, swelling behavior and cytotoxicity studies were performed in comparison with corresponding polymers. Both, disintegration and in vitro mucoadhesive studies revealed that modifying HA-CYS with MNA resulted in higher stability (3.6-fold prolonged disintegration time compared to unmodified hyaluronic acid) and prolonged mucoadhesion time. MTT assay and LDH revealed no toxicity for the polymeric excipients and safe for their use. Disintegration and swelling results conducted more pronounced stability of the preactivated thiomers compared to corresponding unmodified ones. According to these results preactivated hyaluronic acid might be a useful tool for vaginal delivery systems.

  4. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats.

    PubMed

    Lin, Chi-Chang; Fu, Shu-Juan

    2016-01-01

    Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs.

  5. Crosslinked bicontinuous biobased PLA/NR blends via dynamic vulcanization using different curing systems.

    PubMed

    Yuan, Daosheng; Chen, Kunling; Xu, Chuanhui; Chen, Zhonghua; Chen, Yukun

    2014-11-26

    In this study, blends of entirely biosourced polymers, namely polylactide (PLA) and natural rubber (NR), were prepared through dynamic vulcanization using dicumyl peroxide (DCP), sulphur (S) and phenolic resin (2402) as curing agents, respectively. The crosslinked NR phase was found to be a continuous structure in all the prepared blends. The molecular weight changes of PLA were studied by gel permeation chromatography. Interfacial compatibilization between PLA and NR was investigated using Fourier transform infrared spectroscopy and scanning electron microscopy. The thermal properties of blends were evaluated by differential scanning calorimetry and thermogravimetric analysis instrument. It was found that the molecular weight of PLA and interfacial compatibilizaion between PLA and NR showed a significant influence on the mechanical and thermal properties of blends. The PLA/NR blend (60/40 w/w) by DCP-induced dynamic vulcanization owned the finest mechanical properties and thermal stability.

  6. Preparation and characterization of collagen/PLA, chitosan/PLA, and collagen/chitosan/PLA hybrid scaffolds for cartilage tissue engineering.

    PubMed

    Haaparanta, Anne-Marie; Järvinen, Elina; Cengiz, Ibrahim Fatih; Ellä, Ville; Kokkonen, Harri T; Kiviranta, Ilkka; Kellomäki, Minna

    2014-04-01

    In this study, three-dimensional (3D) porous scaffolds were developed for the repair of articular cartilage defects. Novel collagen/polylactide (PLA), chitosan/PLA, and collagen/chitosan/PLA hybrid scaffolds were fabricated by combining freeze-dried natural components and synthetic PLA mesh, where the 3D PLA mesh gives mechanical strength, and the natural polymers, collagen and/or chitosan, mimic the natural cartilage tissue environment of chondrocytes. In total, eight scaffold types were studied: four hybrid structures containing collagen and/or chitosan with PLA, and four parallel plain scaffolds with only collagen and/or chitosan. The potential of these types of scaffolds for cartilage tissue engineering applications were determined by the analysis of the microstructure, water uptake, mechanical strength, and the viability and attachment of adult bovine chondrocytes to the scaffolds. The manufacturing method used was found to be applicable for the manufacturing of hybrid scaffolds with highly porous 3D structures. All the hybrid scaffolds showed a highly porous structure with open pores throughout the scaffold. Collagen was found to bind water inside the structure in all collagen-containing scaffolds better than the chitosan-containing scaffolds, and the plain collagen scaffolds had the highest water absorption. The stiffness of the scaffold was improved by the hybrid structure compared to plain scaffolds. The cell viability and attachment was good in all scaffolds, however, the collagen hybrid scaffolds showed the best penetration of cells into the scaffold. Our results show that from the studied scaffolds the collagen/PLA hybrids are the most promising scaffolds from this group for cartilage tissue engineering.

  7. Differential hydrolysis of erythrocyte and mitochondrial membrane phospholipids by two phospholipase A2 isoenzymes (NK-PLA2-I and NK-PLA2-II) from the venom of the Indian monocled cobra Naja kaouthia.

    PubMed

    Doley, Robin; King, Glenn F; Mukherjee, Ashis K

    2004-05-01

    We previously demonstrated that venom from the Indian monocled cobra Naja kaouthia is a rich source of phospholipase A2 enzymes, and we purified and characterized a major PLA2 isoenzyme (NK-PLA2-I) from N. kaouthia venom. In the present study, we report the purification and biochemical characterization of a second PLA2 isoenzyme (NK-PLA2-II) from the same venom. A comparison of the membrane phospholipid hydrolysis patterns by these two PLA2s has revealed that they cause significantly more damage to mitochondrial membranes (NK-PLA2-I > NK-PLA2-II) as compared to erythrocyte membranes due to more efficient binding of the enzymes to mitochondrial membranes. Fatty acid release patterns by these PLA2s from the membrane phospholipid PC-pools indicate that NK-PLA2-I does not discriminate between saturated and unsaturated fatty acids whereas NK-PLA2-II shows a preference for unsaturated fatty acids during the initial phase of attack. The current investigation provides new insight into the molecular arrangement of NK-PLA2-sensitive domains in erythrocyte and mitochondrial membranes and highlights the contribution of polar, but uncharged, amino acids such as serine and cysteine in NK-PLA2 induced membrane damage.

  8. 40 CFR 721.10395 - Fatty acids, C14-18 and C16-18 unsatd., polymers with adipic acid and triethanolamine, di-Me...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...., polymers with adipic acid and triethanolamine, di-Me sulfate-quaternized. 721.10395 Section 721.10395... Fatty acids, C14-18 and C16-18 unsatd., polymers with adipic acid and triethanolamine, di-Me sulfate... identified as fatty acids, C14-18 and C16-18 unsat., polymers with adipic acid and triethanolamine,...

  9. 40 CFR 721.10395 - Fatty acids, C14-18 and C16-18 unsatd., polymers with adipic acid and triethanolamine, di-Me...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...., polymers with adipic acid and triethanolamine, di-Me sulfate-quaternized. 721.10395 Section 721.10395... Fatty acids, C14-18 and C16-18 unsatd., polymers with adipic acid and triethanolamine, di-Me sulfate... identified as fatty acids, C14-18 and C16-18 unsat., polymers with adipic acid and triethanolamine,...

  10. 40 CFR 721.10395 - Fatty acids, C14-18 and C16-18 unsatd., polymers with adipic acid and triethanolamine, di-Me...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...., polymers with adipic acid and triethanolamine, di-Me sulfate-quaternized. 721.10395 Section 721.10395... Fatty acids, C14-18 and C16-18 unsatd., polymers with adipic acid and triethanolamine, di-Me sulfate... identified as fatty acids, C14-18 and C16-18 unsat., polymers with adipic acid and triethanolamine,...

  11. Effect of surface modification of poly(lactic acid) by low-pressure ammonia plasma on adsorption of human serum albumin

    NASA Astrophysics Data System (ADS)

    Sarapirom, S.; Yu, L. D.; Boonyawan, D.; Chaiwong, C.

    2014-08-01

    The final goal of the study was to promote understanding of mechanisms involved in cell attachment on biomedical polymer poly(lactic acid) (PLA). As the cell attachment on the material surface was preceded by blood protein adsorption which would critically affect subsequent cell adhesion, for the clinic application purpose, human serum albumin (HSA) was used in the investigation on its adsorption on PLA, which was however treated by low-pressure ammonia (NH3) plasma. The NH3-plasma-treated PLA was found to adsorb less HSA than the untreated PLA. The PLA was characterized using various techniques such as atomic force microscopy, contact angle and surface energy analysis and x-ray photoelectron spectroscopy. All of the characterization results indicated that due to NH3-plasma-induced polar groups the PLA enhanced its hydrophilicity which in turn inhibited the HSA adsorption. The decreased HSA adsorption would consequently increase the cell attachment because of the cell adhesion barrier reduced.

  12. sPLA2 and the epidermal barrier

    PubMed Central

    Ilic, Dusko; Bollinger, James M.; Gelb, Michael; Mauro, Theodora M.

    2015-01-01

    The mammalian epidermis provides both an interface and a protective barrier between the organism and its environment. Lipid, processed into water-impermeable bilayers between the outermost layers of the epidermal cells, forms the major barrier that prevents water from exiting the organism, and also prevents toxins and infectious agents from entering. The secretory phospholipase 2 (sPLA2) enzymes control important processes in skin and other organs, including inflammation and differentiation. sPLA2 activity contributes to epidermal barrier formation and homeostasis by generating free fatty acids, which are required both for formation of lamellar membranes and also for acidification of the stratum corneum (SC). sPLA2 is especially important in controlling SC acidification and establishment of an optimum epidermal barrier during the first postnatal week. Several sPLA2 isoforms are present in the epidermis. We find that two of these isoforms, sPLA2 IIA and sPLA2 IIF, localize to the upper stratum granulosum and increase in response to experimental barrier perturbation. sPLA2F−/− mice also demonstrate a more neutral SC pH than do their normal littermates, and their initial recovery from barrier perturbation is delayed. These findings confirm that sPLA2 enzymes perform important roles in epidermal development, and suggest that the sPLA2IIF isoform may be central to SC acidification and barrier function. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias. PMID:24269828

  13. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    NASA Astrophysics Data System (ADS)

    Zou, Wei; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping

    2016-03-01

    Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

  14. The Adipocyte-Inducible Secreted Phospholipases PLA2G5 and PLA2G2E Play Distinct Roles in Obesity

    PubMed Central

    Sato, Hiroyasu; Taketomi, Yoshitaka; Ushida, Ayako; Isogai, Yuki; Kojima, Takumi; Hirabayashi, Tetsuya; Miki, Yoshimi; Yamamoto, Kei; Nishito, Yasumasa; Kobayashi, Tetsuyuki; Ikeda, Kazutaka; Taguchi, Ryo; Hara, Shuntaro; Ida, Satoshi; Miyamoto, Yuji; Watanabe, Masayuki; Baba, Hideo; Miyata, Keishi; Oike, Yuichi; Gelb, Michael H.; Murakami, Makoto

    2014-01-01

    Summary Metabolic disorders including obesity and insulin resistance have their basis in dysregulated lipid metabolism and low-grade inflammation. In a microarray search of unique lipase-related genes whose expressions are associated with obesity, we found that two secreted phospholipase A2s (sPLA2s), PLA2G5 and PLA2G2E, were robustly induced in adipocytes of obese mice. Analyses of Pla2g5−/− and Pla2g2e−/− mice revealed distinct and previously unrecognized roles of these sPLA2s in diet-induced obesity. PLA2G5 hydrolyzed phosphatidylcholine in fat-overladen low-density lipoprotein to release unsaturated fatty acids, which prevented palmitate-induced M1 macrophage polarization. As such, PLA2G5 tipped the immune balance toward an M2 state, thereby counteracting adipose tissue inflammation, insulin resistance, hyperlipidemia and obesiy. PLA2G2E altered minor lipoprotein phospholipids, phosphatidylserine and phosphatidylethanolamine, and moderately facilitated lipid accumulation in adipose tissue and liver. Collectively, the identification of “metabolic sPLA2s” adds this gene family to a growing list of lipolytic enzymes that act as metabolic coordinators. PMID:24910243

  15. Polymer coatings to passivate calcite from acid attack: polyacrylic acid and polyacrylonitrile.

    PubMed

    Thompson, Mary; Wilkins, Shelley J; Compton, Richard G; Viles, Heather A

    2003-04-01

    The extent of passivation of calcite toward dissolution by aqueous acids arising from polymeric coatings based on polyacrylic acid or polyacrylonitrile is evaluated using a channel flow cell technique with microdisc electrode detection. In situ passivation with polyacrylic acid leads to a reduction in the reactivity of calcite toward acid attack with a reduction in the rate constant by up to an order of magnitude compared with untreated calcite. Ex situ passivation with polyacrylic acid for 24 h results in good coverage of the calcite by the polymer but it is shown to erode from the surface when exposed to an aqueous acid solution. In contrast, polyacrylonitrile is demonstrated to form a regular coating after exposure for just 1 h and offers robust potent protection from aqueous acid attack.

  16. Electrospun PCL/PLA/HA based nanofibers as scaffold for osteoblast-like cells.

    PubMed

    Fang, Rui; Zhang, Enwei; Xu, Ling; Wei, Shicheng

    2010-11-01

    Polycaprolactone (PCL), poly (lactic acid) (PLA) and hydroxyapatite (HA) are frequently used as materials for tissue engineering. In this study, PCL/PLA/HA nanofiber mats with different weight ratio were prepared using electrospinning. Their structure and morphology were studied by FTIR and FESEM. FTIR results demonstrated that the HA particles were successfully incorporated into the PCL/PLA nanofibers. The FESEM images showed that the surface of fibers became coarser with the introduction of HA nanoparticles into PCL/PLA system. Furthermore, the addition of HA led to the decreasing of fiber diameter. The average diameters of PCL/PLA/HA nanofiber were in the range of 300-600 nm, while that of PCL/PLA was 776 +/- 15.4 nm. The effect of nanofiber composition on the osteoblast-like MC3T3-E1 cell adhesion and proliferation were investigated as the preliminary biological evaluation of the scaffold. The MC3T3-E1 cell could be attached actively on all the scaffolds. The MTT assay revealed that PCL/PLA/HA scaffold shows significantly higher cell proliferation than PCL/PLA scaffolds. After 15 days of culture, mineral particles on the surface of the cells was appeared on PCL/PLA/HA nanofibers while normal cell spreading morphology on PCL/PLA nanofibers. These results manifested that electrospun PCL/PLA/HA scaffolds could enhance bone regeneration, showing their marvelous prospect as scaffolds for bone tissue engineering.

  17. Blending Novatein¯ thermoplastic protein with PLA for carbon dioxide assisted batch foaming

    NASA Astrophysics Data System (ADS)

    Walallavita, Anuradha; Verbeek, Casparus J. R.; Lay, Mark

    2016-03-01

    The convenience of polymeric foams has led to their widespread utilisation in everyday life. However, disposal of synthetic petroleum-derived foams has had a detrimental effect on the environment which needs to be addressed. This study uses a clean and sustainable approach to investigate the foaming capability of a blend of two biodegradable polymers, polylactic acid (PLA) and Novatein® Thermoplastic Protein (NTP). PLA, derived from corn starch, can successfully be foamed using a batch technique developed by the Biopolymer Network Ltd. NTP is a patented formulation of bloodmeal and chemical additives which can be extruded and injection moulded similar to other thermoplastics. However, foaming NTP is a new area of study and its interaction with blowing agents in the batch process is entirely unknown. Subcritical and supercritical carbon dioxide have been examined individually in two uniquely designed pressure vessels to foam various compositions of NTP-PLA blends. Foamed material were characterised in terms of expansion ratio, cell size, and cellular morphology in order to study how the composition of NTP-PLA affects foaming with carbon dioxide. It was found that blends with 5 wt. % NTP foamed using subcritical CO2 expanded up to 11 times due to heterogeneous nucleation. Morphology analysis using scanning electron microscopy showed that foams blown with supercritical CO2 had a finer cell structure with consistent cell size, whereas, foams blown with subcritical CO2 ranged in cell size and showed cell wall rupture. Ultimately, this research would contribute to the production of a biodegradable foam material to be used in packaging applications, thereby adding to the application potential of NTP.

  18. The influence of polymer topology on pharmacokinetics: differences between cyclic and linear PEGylated poly(acrylic acid) comb polymers.

    PubMed

    Chen, Bo; Jerger, Katherine; Fréchet, Jean M J; Szoka, Francis C

    2009-12-16

    Water-soluble polymers for the delivery of chemotherapeutic drugs passively target solid tumors as a consequence of reduced renal clearance and the enhanced permeation and retention (EPR) effect. Elimination of the polymers in the kidney occurs due to filtration through biological nanopores with a hydrodynamic diameter comparable to the polymer. Therefore we have investigated chemical features that may broadly be grouped as "molecular architecture" such as: molecular weight, chain flexibility, number of chain ends and branching, to learn how they impact polymer elimination. In this report we describe the synthesis of four pairs of similar molecular weight cyclic and linear polyacrylic acid polymers grafted with polyethylene glycol (23, 32, 65, 114 kDa) with low polydispersities using ATRP and "click" chemistry. The polymers were radiolabeled with (125)I and their pharmacokinetics and tissue distribution after intravenous injection were determined in normal and C26 adenocarcinoma tumored BALB/c mice. Cyclic polymers above the renal threshold of 30 kDa had a significantly longer elimination time (between 10 and 33% longer) than did the comparable linear polymer (for the 66 kDa cyclic polymer, t(1/2,beta)=35+/-2 h) and a greater area under the serum concentration versus time curve. This resulted in a greater tumor accumulation of the cyclic polymer than the linear polymer counterpart. Thus water-soluble cyclic comb polymers join a growing list of polymer topologies that show greatly extended circulation times compared to their linear counterparts and provide alternative polymer architecture for use as drug carriers.

  19. 40 CFR 721.6680 - Alkanoic acid, butanediol and cyclohexanealkanol polymer (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... cyclohexanealkanol polymer (generic name). 721.6680 Section 721.6680 Protection of Environment ENVIRONMENTAL... cyclohexanealkanol polymer (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkanoic acid, butanediol, and cyclohexanealkanol polymer (PMN P-89-672)...

  20. 40 CFR 721.6680 - Alkanoic acid, butanediol and cyclohexanealkanol polymer (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... cyclohexanealkanol polymer (generic name). 721.6680 Section 721.6680 Protection of Environment ENVIRONMENTAL... cyclohexanealkanol polymer (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkanoic acid, butanediol, and cyclohexanealkanol polymer (PMN P-89-672)...

  1. 40 CFR 721.6680 - Alkanoic acid, butanediol and cyclohexanealkanol polymer (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... cyclohexanealkanol polymer (generic name). 721.6680 Section 721.6680 Protection of Environment ENVIRONMENTAL... cyclohexanealkanol polymer (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkanoic acid, butanediol, and cyclohexanealkanol polymer (PMN P-89-672)...

  2. 40 CFR 721.6680 - Alkanoic acid, butanediol and cyclohexanealkanol polymer (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... cyclohexanealkanol polymer (generic name). 721.6680 Section 721.6680 Protection of Environment ENVIRONMENTAL... cyclohexanealkanol polymer (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkanoic acid, butanediol, and cyclohexanealkanol polymer (PMN P-89-672)...

  3. 40 CFR 721.6680 - Alkanoic acid, butanediol and cyclohexanealkanol polymer (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... cyclohexanealkanol polymer (generic name). 721.6680 Section 721.6680 Protection of Environment ENVIRONMENTAL... cyclohexanealkanol polymer (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkanoic acid, butanediol, and cyclohexanealkanol polymer (PMN P-89-672)...

  4. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... substituted oxirane, formaldehyde-phenol polymer glycidyl ether, substituted proplyamine and...-phenol polymer glycidyl ether, substituted proplyamine and polyethylenepolyamines (generic). (a) Chemical... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  5. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... substituted oxirane, formaldehyde-phenol polymer glycidyl ether, substituted proplyamine and...-phenol polymer glycidyl ether, substituted proplyamine and polyethylenepolyamines (generic). (a) Chemical... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  6. Effects of electron beam irradiation on the structural properties of polylactic acid/polyethylene blends

    NASA Astrophysics Data System (ADS)

    Bee, Soo-Tueen; Ratnam, C. T.; Sin, Lee Tin; Tee, Tiam-Ting; Wong, Wai-Kien; Lee, Jiuun-Xiang; Rahmat, A. R.

    2014-09-01

    The purpose of this research was to investigate the effects of electron beam irradiation on the properties of polylactic acid (PLA) and low density polyethylene (LDPE) blends. The PLA were compounded with 20-80% LDPE and were exposed to electron beam irradiation dosages of 20-120 kGy. The results from gel content and X-ray diffraction analyses showed that the addition of LDPE to PLA effectively increased the gel content and crystallinity. However, an increasing percentage of LDPE reduced the tensile strength and Young's modulus of the PLA/LDPE samples due to the lower intermolecular bonding of LDPE than of PLA. Moreover, an increase in irradiation dosages gradually decreased the mechanical properties of low-LDPE PLA/LDPE. In contrast, the increasing irradiation dosage enhanced the mechanical properties of higher-LDPE PLA/LDPE. These results indicate that higher amounts of LDPE effectively react with the release of free radicals within the amorphous phase if the blends are subjected to irradiation. The higher amounts of free radicals induce the formation of three-dimensional cross-linked networks in the polymer matrix and thus increase the gel content. The irradiation-induced cross-linking in PLA/LDPE samples improves the mechanical properties and crystallinity by promoting a structural rearrangement of the polymer matrix into a highly ordered structure.

  7. Cell morphology of extrusion foamed poly(lactic acid) using endothermic chemical foaming agent.

    PubMed

    Matuana, Laurent M; Faruk, Omar; Diaz, Carlos A

    2009-12-01

    Poly(lactic acid) (PLA) was foamed with an endothermic chemical foaming agent (CFA) through an extrusion process. The effects of polymer melt flow index, CFA content, and processing speed on the cellular structures, void fraction, and cell-population density of foamed PLA were investigated. The apparent melt viscosity of PLA was measured to understand the effect of melt index on the cell morphology of foamed PLA samples. The void fraction was strongly dependent on the PLA melt index. It increased with increasing melt index, reaching a maximum value, after which it decreased. Melt index showed no significant effect on the cell-population density of foamed samples within the narrow range studied. A gas containment limit was observed in PLA foamed with CFA. Both the void fraction and cell-population density increased with an initial increase in CFA content, reached a maximum value, and then decreased as CFA content continued to increase. The processing speed also affected the morphology of PLA foams. The void fraction reached a maximum value as the extruder's screw speed increased to 40 rpm and a further increase in the processing speed tended to reduce the void fraction of foamed samples. By contrast, cell-population density increased one order of magnitude by increasing the screw speed from 20 to 120 rpm. The experimental results indicate that a homogeneous and finer cellular morphology could be successfully achieved in PLA foamed in an extrusion process with a proper combination of polymer melt flow index, CFA content, and processing speed.

  8. Poly(L-lactic acid)/poly(glycolic acid) microfibrillar polymer-polymer composites: Preparation and viscoelastic properties

    NASA Astrophysics Data System (ADS)

    Kimble, L. D.; Fakirov, S.; Bhattacharyya, D.

    2015-05-01

    Microfibrillar composites (MFCs) from petrochemical-derived polymers have been investigated for several years and the technique can result in significant improvements in mechanical properties when compared with the neat matrix material of the respective composite. The current work applies the technique to biodegradable, biocompatible polymers for potential applications in bioabsorbable medical devices. MFCs were prepared from melt blended poly(L-lactic acid) (PLLA) and poly(glycolic acid) (PGA) via cold drawing then compression molding of extruded yarn. These MFCs were shown to have higher Young's moduli than that of neat PLLA but for load-bearing applications the creep characteristics are of interest. The MFC sheets resulting from compression molding were subjected to tensile relaxation tests at 37°C in the fiber orientation direction. Specimens were also tested via dynamic mechanical thermal analysis (DMTA). Neat PLLA specimens were subjected to the same tests for comparison. Results indicate that at 37°C PLLA/PGA MFCs exhibit lower creep resistance than that of neat PLLA due to the more rapid relaxation of stress observed. DMTA results elucidate the loss modulus changes in PLLA/PGA MFCs which occur as the material approaches the glass transition temperature of PGA (˜45°C).

  9. Ferulic Acid-Based Polymers with Glycol Functionality as a Versatile Platform for Topical Applications.

    PubMed

    Ouimet, Michelle A; Faig, Jonathan J; Yu, Weiling; Uhrich, Kathryn E

    2015-09-14

    Ferulic acid-based polymers with aliphatic linkages have been previously synthesized via solution polymerization methods, yet they feature relatively slow ferulic acid release rates (∼11 months to 100% completion). To achieve a more rapid release rate as required in skin care formulations, ferulic acid-based polymers with ethylene glycol linkers were prepared to increase hydrophilicity and, in turn, increase ferulic acid release rates. The polymers were characterized using nuclear magnetic resonance and Fourier transform infrared spectroscopies to confirm chemical composition. The molecular weights, thermal properties (e.g., glass transition temperature), and contact angles were also obtained and the polymers compared. Polymer glass transition temperature was observed to decrease with increasing linker molecule length, whereas increasing oxygen content decreased polymer contact angle. The polymers' chemical structures and physical properties were shown to influence ferulic acid release rates and antioxidant activity. In all polymers, ferulic acid release was achieved with no bioactive decomposition. These polymers demonstrate the ability to strategically release ferulic acid at rates and concentrations relevant for topical applications such as skin care products.

  10. Application of Lemongrass Oil-Containing Polylactic Acid Films to the Packaging of Pork Sausages.

    PubMed

    Yang, Hyun-Ju; Song, Kyung Bin

    2016-01-01

    Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging.

  11. Softened and flexible biodegradable poly(lactic acid) and its electromechanical properties for actuator application.

    PubMed

    Thummarungsan, Natlita; Pattavarakorn, Datchanee; Sirivat, Anuvat

    2016-12-01

    Poly (lactic acid) (PLA) is a biodegradable polymer with high stiffness presenting a limitation for using in actuator applications. Adding a plasticizer is one way to solve this problem to enhance flexibility and improve electromechanical properties of pristine PLA. In this work, the PLA films were prepared via a simple solvent casting method. The influences of plasticizer type and electric field strength on electromechanical behavior of PLA films were investigated by the melt rheometer and bending measurement. For the PLA films filled with dibutyl phthalate (DBP), the storage modulus, G', immediately increased towards its steady state and rapidly recovered to its original value with and without electric field, respectively, which can be referred to a reversible system. On the other hand, the PLA film with Tween 20 processed the highest ∆G׳/G׳0 of 1.34 due to the available amount of polarized groups. In the bending measurement, the dielectrophoresis forces of plasticized PLA films were found to increase with increasing electric field where the deflections occurred towards anode side as the polarized groups generated negative charges. The DBP_PLA1.5D film exhibited the greatest bending and dielectrophoresis force. Thus, the biodegradable PLA along with DBP combine to have a great potential towards actuator application.

  12. Application of Lemongrass Oil-Containing Polylactic Acid Films to the Packaging of Pork Sausages

    PubMed Central

    2016-01-01

    Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging. PMID:27433114

  13. A Scanning Electron Microscopic Study of Cell Attachment to Biodegradable Polymer Implants

    DTIC Science & Technology

    1988-08-15

    attachment ABSTRACT Y he biodegradable polymers, polylactic acid (PLA) and polyglycolic acid (PGA) are currently being studied as carriers for bioactive bone ...Research focuses on their use for sustained antibiotic delivery, bone fracture stabilization, moldable osseous repair materials and as vehicles for...hydrolytic scission which may be mediated by a variety of proteolytic enzymes. (1 ,7) Through this process, both lactic acid and glycolic acid , the respective

  14. 76 FR 41135 - 2-Propenoic acid, 2-methyl-, phenylmethyl ester, polymer with 2-propenoic acid and sodium 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-13

    ... and sodium 2-methyl-2- -1- propanesulfonate (1:1), peroxydisulfuric acid ( 202) sodium salt (1:2...-Propenoic acid, 2-methyl-, phenylmethyl ester, polymer with 2-propenoic acid and sodium 2-methyl- 2- -1-propanesulfonate (1:1), peroxydisulfuric acid ( 202) sodium salt (1:2)-initiated (also known here as: ``the...

  15. Homocomposites of Polylactide (PLA) with Induced Interfacial Stereocomplex Crystallites

    PubMed Central

    2015-01-01

    The demand for “green” degradable composite materials increases with growing environmental awareness. The key challenge is achieving the preferred physical properties and maintaining their eco-attributes in terms of the degradability of the matrix and the filler. Herein, we have designed a series of “green” homocomposites materials based purely on polylactide (PLA) polymers with different structures. Film-extruded homocomposites were prepared by melt-blending PLA matrixes (which had different degrees of crystallinity) with PLLA and PLA stereocomplex (SC) particles. The PLLA and SC particles were spherical and with 300–500 nm size. Interfacial crystalline structures in the form of stereocomplexes were obtained for certain particulate-homocomposite formulations. These SC crystallites were found at the particle/matrix interface when adding PLLA particles to a PLA matrix with d-lactide units, as confirmed by XRD and DSC data analyses. For all homocomposites, the PLLA and SC particles acted as nucleating agents and enhanced the crystallization of the PLA matrixes. The SC particles were more rigid and had a higher Young’s modulus compared with the PLLA particles. The mechanical properties of the homocomposites varied with particle size, rigidity, and the interfacial adhesion between the particles and the matrix. An improved tensile strength in the homocomposites was achieved from the interfacial stereocomplex formation. Hereafter, homocomposites with tunable crystalline arrangements and subsequently physical properties, are promising alternatives in strive for eco-composites and by this, creating materials that are completely degradable and sustainable. PMID:26523245

  16. Properties of PLA/PCL particles as vehicles for oral delivery of the androgen hormone 17α-methyltestosterone.

    PubMed

    Sacchetin, Priscila Soares Costa; Setti, Rafaela Ferreira; Vieira e Rosa, Paulo de Tarso; Moraes, Ângela Maria

    2016-01-01

    The aim of this study was to produce PLA (poly(lactic acid)) and PCL (polycaprolactone) oral carriers through the precipitation of the polymer solutions using supercritical CO2 as an antisolvent for the controlled release of the hydrophobic model drug 17α-methyltestosterone (MT). Such drug is a steroidal hormone used orally to develop and sustain primary and secondary male sex characteristics, e.g. for female Nile tilapia sex reversal in aquaculture. The influence of hormone, PLA and PCL concentrations on particle formation was analyzed, showing that high PCL concentrations produced particles with rougher surfaces and greater mean diameters. The incorporation efficiency of MT ranged from 20 to 51%, and its addition resulted in increases in particle mean diameter from 23 to 54 μm. Aggregation was observed for particles incorporating or not MT and high concentrations of MT led to the formation of more amorphous structures, changing the thermal behavior of the particles. The exposure of the PLA/PCL particles to pH conditions simulating gastrointestinal fish conditions showed that hormone release fraction at acidic pH ranged from 8 to 63% (over 2h), while in the basic pH the proportion released varied from 23 to 60% (over 10h), reaching levels adequate for the desired in vivo activity.

  17. Doped Chiral Polymer Metamaterials

    NASA Technical Reports Server (NTRS)

    Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Gordon, Keith L. (Inventor); Sauti, Godfrey (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert G. (Inventor)

    2017-01-01

    Some implementations provide a composite material that includes a first material and a second material. In some implementations, the composite material is a metamaterial. The first material includes a chiral polymer (e.g., crystalline chiral helical polymer, poly-.gamma.-benzyl-L-glutamate (PBLG), poly-L-lactic acid (PLA), polypeptide, and/or polyacetylene). The second material is within the chiral polymer. The first material and the second material are configured to provide an effective index of refraction value for the composite material of 1 or less. In some implementations, the effective index of refraction value for the composite material is negative. In some implementations, the effective index of refraction value for the composite material of 1 or less is at least in a wavelength of one of at least a visible spectrum, an infrared spectrum, a microwave spectrum, and/or an ultraviolet spectrum.

  18. 76 FR 52875 - 2-Propenoic Acid, Polymer With Ethenylbenzene and (1-methylethenyl) Benzene, Sodium Salt...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-24

    ..., Sodium Salt; Tolerance Exemption AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule...-Propenoic acid, polymer with ethenylbenzene and (1-methylethenyl) benzene, sodium salt when used as an inert... residues of 2-Propenoic acid, polymer with ethenylbenzene and (1- methylethenyl) benzene, sodium salt...

  19. Effect of polymer/clay composition on processability of polylactide nanocomposites by film blowing

    NASA Astrophysics Data System (ADS)

    Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Di Maio, L.; Incarnato, L.

    2015-12-01

    The blown extrusion of poly(lactic acid) presents several challenges mainly due to its poor elongation properties. This work deals on the possibility to enhance the processabiliy of PLA by film blowing by functionalizing the polymer with nanosilicates. In particular, two types of polylactic acid (PLA 4032D and PLA 4042D) and different types of filler, selected from montmorillonites (Cloisite 30B) and bentonites (Nanofil SE3010) families, were used to prepare the hybrid systems by using a twin-screw extruder. The interaction between the polymer and the clay was evaluated by FTIR analysis and correlated to the structure of the obtained nanocomposites in terms of clay dispersion. All the samples were then submitted to rheological measurements both in shear and elongational mode.

  20. Investigation of the Effect of Mixing Methods and Chemical Treatments on the Conductivity of the CNT/PLA Based Composites

    NASA Astrophysics Data System (ADS)

    Talwar, Brijpal Singh

    The growing popularity of Poly lactic acid (PLA) is mainly due to its biocompatibility, good mechanical properties, and its synthesis from renewable resources. PLA can be compounded with electrically conductive fillers (e.g., carbon nanotubes (CNTs)) to form conductive polymer composites (CPCs). These fillers provide conductive functionality to the composite material by forming percolation paths. Featuring very low weight densities, CPCs have the potential to replace metals in the electronic industry, if they exhibit similar electrical conductivities to that of the metals. The current challenges being faced during the mixing of CNTs in the polymer matrix are: formation of aggregates due to strong van der Waals forces and breakage of CNTs during dispersion. In this study, we compare: (1) two fabrication methods to create CPCs (i.e., solution mixing by sonication and melt extrusion) (2) effect of various CNT functionalization techniques (i.e., acid and plasma treatments) on the conductivity of CPCs and (3) effect of using binding molecules like para-phenylenediamine, that act as bridges in between the CNTs in the CPCs and its effect on the conductivity of CPCs. Such conductive composite materials find widespread technological applications which either require, or could benefit from, the ability to pattern micro-sized features in two-dimensional (2D) and three-dimensional (3D) architectures. Direct-write fabrication technique is used to realise these printed patterns, using the CPC solution as ink. First, the composites comprising of 30% PLA by weight in Dichloromethane (DCM) and CNTs in different concentrations (up to 5wt. %) are fabricated using a two-step sonication method (i.e., dissolving PLA in DCM and then dispersing the CNTs in this polymer solution). Second, CPCs are fabricated using a twin screw micro extruder operating at 180°C. To verify the effects of functionalization of the CNTs on the conductivity of composites, the CNTs are functionalized by three

  1. Poly(lactic acid)/natural rubber/cellulose nanocrystal bionanocomposites. Part II: properties evaluation.

    PubMed

    Bitinis, Natacha; Fortunati, Elena; Verdejo, Raquel; Bras, Julien; Kenny, Jose Maria; Torre, Luigi; López-Manchado, Miguel Angel

    2013-07-25

    The crystallization, mechanical and biodegradation properties of poly(lactic acid)/natural rubber/cellulose nanocrystals (CNC) bionanocomposites were evaluated. Three types of CNC were used in this study, one unmodified (CNC), long alkyl chain grafted CNC (C18-g-CNC) and PLA grafted CNC (PLA-g-CNC). The CNC modifications determined the affinity of the nanocrystals toward the polymers and reflected on the ultimate properties. Interestingly, PLA-g-CNC acted as a nucleating agent for the PLA matrix in the bio-based PLA/NR blend. Good mechanical properties were reported, as the bionanocomposites maintained a high elongation at break for a concentration up to 3 wt.% of cellulose nanocrystals. Moreover, the disintegration study confirmed that the materials completely disintegrated after one month in compost.

  2. Growth and osteogenic differentiation of adipose stem cells on PLA/bioactive glass and PLA/beta-TCP scaffolds.

    PubMed

    Haimi, Suvi; Suuriniemi, Niina; Haaparanta, Anne-Marie; Ellä, Ville; Lindroos, Bettina; Huhtala, Heini; Räty, Sari; Kuokkanen, Hannu; Sándor, George K; Kellomäki, Minna; Miettinen, Susanna; Suuronen, Riitta

    2009-07-01

    The aim of this study was to compare the effects of novel three-dimensional composite scaffolds consisting of a bioactive phase (bioactive glass or beta-tricalcium phosphate [beta-TCP] 10 and 20 wt%) incorporated within a polylactic acid (PLA) matrix on viability, distribution, proliferation, and osteogenic differentiation of human adipose stem cells (ASCs). The viability and distribution of ASCs on the bioactive composite scaffolds was evaluated using Live/Dead fluorescence staining, environmental scanning electron microscopy, and scanning electron microscopy. There were no differences between the two concentrations of bioactive glass and beta-TCP in PLA scaffolds on proliferation and osteogenic differentiation of ASCs. After 2 weeks of culture, DNA content and alkaline phosphatase (ALP) activity of ASCs cultured on PLA/beta-TCP composite scaffolds were higher relative to other scaffold types. Interestingly, the cell number was significantly lower, but the relative ALP/DNA ratio of ASCs was significantly higher in PLA/bioactive glass scaffolds than in other three scaffold types. These results indicate that the PLA/beta-TCP composite scaffolds significantly enhance ASC proliferation and total ALP activity compared to other scaffold types. This supports the potential future use of PLA/beta-TCP composites as effective scaffolds for tissue engineering and as bone replacement materials.

  3. Investigation on thermoformability of PLA by rheological and hot tensile tests

    NASA Astrophysics Data System (ADS)

    Garofalo, Emilia; Iannaccone, Giovanni; Scarfato, Paola; Di Maio, Luciano; Incarnato, Loredana

    2012-07-01

    In this work the correlation between the thermoformability of different grades of polylactide acid (PLA 4032D, PLA 4042D and PLA 2003D) and their mechanical, thermal, and rheological properties was explored. In particular, hot tensile tests, at different stretching temperatures and crosshead speeds, were performed in order to identify an optimum windows of temperature and strain rate for improved thermoforming performance. The properties measured from the creep experiments were correlated with the propensity of PLA sheet to sag, while the unrecovered strains by the creep recovery tests were associated to mold replication attitude of the materials investigated.

  4. Reinforcement of a porous collagen scaffold with surface-activated PLA fibers.

    PubMed

    Liu, Xi; Huang, Changbin; Feng, Yujie; Liang, Jie; Fan, Yujiang; Gu, Zhongwei; Zhang, Xingdong

    2010-01-01

    A hybrid porous collagen scaffold mechanically reinforced with surface-activated poly(lactic acid) (PLA) fiber was prepared. PLA fibers, 20 mum in diameter and 1 mm in length, were aminolyzed with hexanediamine to introduce free amino groups on the surfaces. After the amino groups were transferred to aldehyde groups by treatment with glutaraldehyde, different amounts (1.5, 3, 5 and 8 mg) of surface-activated PLA fibers were homogeneously mixed with 2 ml type-I collagen solution (pH 2.8, 0.6 wt%). This mixture solution was then freeze-dried and cross-linked to obtain collagen sponges with surface-activated PLA fiber. Scanning electron microscopy observation indicated that the collagen sponges had a highly interconnected porous structure with an average pore size of 170 mum, irrespective of PLA fiber incorporation. The dispersion of surface-activated PLA fibers was homogeneous in collagen sponge, in contrast to unactivated PLA fibers. The compression modulus test results showed that, compared with unactivated PLA fibers, the surface-activated PLA fibers enhanced the resistance of collagen sponge to compression more significantly. Cytotoxicity assay by MTT test showed no cytotoxicity of these collagen sponges. L929 mouse fibroblast cell-culture studies in vitro revealed that the number of L929 cells attached to the collagen sponge with surface-activated PLA fibers, both 6 h and 24 h after seeding, was higher than that in pure collagen sponge and sponge with unactivated PLA fibers. In addition, a better distribution of cells infiltrated in collagen sponge with surface-activated PLA fibers was observed by histological staining. These results indicated that the collagen sponge reinforced with surface-activated PLA fibers is a promising biocompatible scaffold for tissue engineering.

  5. Functionalized graphene with polymer toughener as novel interface modifier for property-tailored poly(lactic acid)/graphene nanocomposites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work, an effective strategy for engineering the interfacial compatibility between graphene and polylactic acid (PLA) was developed by manipulating the functionalization of graphene and introducing an epoxy-containing elastomer modifier. Curing between the functional groups of the modified gr...

  6. 75 FR 4292 - 2-Propenoic acid, 2-ethylhexyl ester, polymer with ethenylbenzene and 2-methylpropyl 2-methyl-2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-27

    ... AGENCY 40 CFR Part 180 2-Propenoic acid, 2-ethylhexyl ester, polymer with ethenylbenzene and 2... residues of 2-propenoic acid, 2-ethylhexyl ester, polymer with ethenylbenzene and 2-methylpropyl 2-methyl-2... permissible level for residues of 2-propenoic acid, 2-ethylhexyl ester, polymer with ethenylbenzene and...

  7. 40 CFR 721.6980 - Dimer acids, polymer with polyalkylene glycol, bisphenol A-diglycidyl ether, and alky-lenepolyols...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Dimer acids, polymer with polyalkylene... Substances § 721.6980 Dimer acids, polymer with polyalkylene glycol, bisphenol A-diglycidyl ether, and alky... reporting. (1) The chemical substance dimer acids, polymer with polyalkylene glycol, bisphenol...

  8. 40 CFR 721.6980 - Dimer acids, polymer with polyalkylene glycol, bisphenol A-diglycidyl ether, and alky-lenepolyols...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dimer acids, polymer with polyalkylene... Substances § 721.6980 Dimer acids, polymer with polyalkylene glycol, bisphenol A-diglycidyl ether, and alky... reporting. (1) The chemical substance dimer acids, polymer with polyalkylene glycol, bisphenol...

  9. Fibrous scaffolds made by co-electrospinning soluble eggshell membrane protein with biodegradable synthetic polymers.

    PubMed

    Xiong, Xi; Li, Qiang; Lu, Jian-Wei; Guo, Zhao-Xia; Sun, Zhao-Hui; Yu, Jian

    2012-01-01

    Soluble eggshell membrane protein (SEP), isolated from natural eggshell membrane, was co-electrospun with biodegradable synthetic polymers poly(propylene carbonate) (PPC) and poly(lactic acid) (PLA) in various proportions from 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) solutions in order to prepare fibrous scaffolds having simultaneously good mechanical properties and biocompatibility. The fiber morphology was observed by field emission scanning electron microscopy, showing uniform fibers with diameter of 1.2-1.0 and 1.3-0.7 um for PPC/SEP and PLA/SEP blend fibers, respectively. Transmission electron microscopy observation shows that the blend fibers have domain-matrix phase morphology with fiber-like SEP domains in the PPC or PLA matrix, indicating the occurrence of phase separation, although interaction exists between PPC (or PLA) and SEP, as revealed by attenuated total reflectance Fourier transform infrared spectroscopy. The mechanical properties were evaluated by uniaxial tensile tests and showed that both the tensile strength and elongation at break increase with increasing incorporation of PPC (or PLA). The surface composition was investigated by X-ray photoelectron spectroscopy and SEP was found on the fiber surfaces, and as a result the surfaces of the fibrous scaffolds are superhydrophilic. NIH3T3 cell culture tests demonstrate that the PPC/SEP and PLA/SEP blend fibrous scaffolds have a much improved biocompatibility compared to pure PPC or PLA fibrous scaffolds.

  10. 40 CFR 721.10690 - Benzenedicarboxylic acid, polymer with substituted alkanediol, dodecanedioic acid, 1,2-ethanediol...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzenedicarboxylic acid, polymer with substituted alkanediol, dodecanedioic acid, 1,2-ethanediol, alkanedioic acid, alkanediol,.alpha.-hydro-.omega.-hydroxypoly , 1,3-isobenzofurandione, methylene diphenyl diisocyanate, 2-oxepanone, 2,2'-oxybis and polymethylene polyphenylene...

  11. Potential of a PLA-PEO-PLA-based scaffold for skin tissue engineering: in vitro evaluation.

    PubMed

    Garric, Xavier; Guillaume, Olivier; Dabboue, Hinda; Vert, Michel; Molès, Jean-Pierre

    2012-01-01

    This study aimed to investigate the in vitro behaviour of porous degradable scaffolds of the PLA-PEO-PLA-type designed prior to in vivo evaluation for skin tissue engineering. Two tri-block co-polymers were synthesized from PEO and DL-lactide and their degradation was studied under conditions that mimic a cutaneous wound environment. 3-D porous scaffolds with interconnected pores were fabricated using the salt leaching method and characterized by ESEM and Hg porosimetry. The degrading action of gamma sterilization was studied on the co-polymers. The less degraded one was selected to make porous scaffolds on which human dermal fibroblasts and human epidermal keratinocytes were cultured. The capacity of such scaffolds to act as a dermal equivalent was also considered. Colonization by human dermal fibroblasts was shown after hematoxylin staining and the production of major proteins normally found in the extracellular matrix was assessed by Western blotting of protein extracts. Finally, a skin substitute was generated by seeding human keratinocytes on the dermal equivalent and a new epidermis was characterized by using immuno-histological staining. Results show that gamma sterilization and that degradation under conditions that mimic skin wound healing were acceptable. The fact that fibroblasts produce extracellular matrix and that keratinocytes generated an epidermal barrier argues in favour of the interest of this type of porous scaffold for skin reconstruction.

  12. Design of polymer motifs for nucleic acid recognition and assembly stabilization

    NASA Astrophysics Data System (ADS)

    Zhou, Zhun

    This dissertation describes the synthesis and assembly of bio-functional polymers and the applications of these polymers to drug encapsulation, delivery, and multivalent biomimetic macromolecular recognition between synthetic polymer and nucleic acids. The main content is divided into three parts: (1) polyacidic domains as strongly stabilizing design elements for aqueous phase polyacrylate diblock assembly; (2) small molecule/polymer recognition triggered macromolecular assembly and drug encapsulation; (3) trizaine derivatized polymer as a novel class of "bifacial polymer nucleic acid" (bPoNA) and applications of bPoNA to nanoparticle loading of DNA/RNA, silencing delivery as well as control of aptamer function. Through the studies in part (1) and part (2), it was demonstrated that well-designed polymer motifs are not only able to enhance assemblies driven by non-specific hydrophobic effect, but are also able to direct assemblies based on specific recognitions. In part (3) of this dissertation, this concept was further extended by the design of polyacrylate polymers that are capable of discrete and robust hybridization with nucleic acids. This surprising finding demonstrated both fundamental and practical applications. Overall, these studies provided insights into the rational design elements for improving the bio-functions of synthetic polymers, and significantly expanded the scope of biological applications in which polymers synthesized via controlled radical polymerization may play a role.

  13. Exploring the role of polymer structure on intracellular nucleic acid delivery via polymeric nanoparticles.

    PubMed

    Bishop, Corey J; Kozielski, Kristen L; Green, Jordan J

    2015-12-10

    Intracellular nucleic acid delivery has the potential to treat many genetically-based diseases, however, gene delivery safety and efficacy remains a challenging obstacle. One promising approach is the use of polymers to form polymeric nanoparticles with nucleic acids that have led to exciting advances in non-viral gene delivery. Understanding the successes and failures of gene delivery polymers and structures is the key to engineering optimal polymers for gene delivery in the future. This article discusses the polymer structural features that enable effective intracellular delivery of DNA and RNA, including protection of nucleic acid cargo, cellular uptake, endosomal escape, vector unpacking, and delivery to the intracellular site of activity. The chemical properties that aid in each step of intracellular nucleic acid delivery are described and specific structures of note are highlighted. Understanding the chemical design parameters of polymeric nucleic acid delivery nanoparticles is important to achieving the goal of safe and effective non-viral genetic nanomedicine.

  14. Structure and blood compatibility of highly oriented PLA/MWNTs composites produced by solid hot drawing.

    PubMed

    Li, Zhengqiu; Zhao, Xiaowen; Ye, Lin; Coates, Phil; Caton-Rose, Fin; Martyn, Michasel

    2014-03-01

    Highly oriented poly(lactic acid) (PLA)/multi-walled carbon nanotubes (MWNTs) composites were fabricated through solid hot drawing technology in an effort to improve the mechanical properties and blood biocompatibility of PLA as blood-contacting medical devices. It was found that proper MWNTs content and drawing orientation can improve the tensile strength and modulus of PLA dramatically. With the increase in draw ratio, the cold crystallization peak became smaller, and the glass transition and the melting peak of PLA moved to high temperature, while the crystallinity increased, and the grain size decreased, indicating the stress-induced crystallization of PLA during drawing. MWNTs showed a nucleation effect on PLA, leading to the rise in the melting temperature, increase in crystallinity and reduction of spherulite size for the composites. Moreover, the intensity of (002) diffraction of MWNTs increased with draw ratio, indicating that MWNTs were preferentially aligned and oriented during drawing. Microstructure observation demonstrated that PLA matrix had an ordered fibrillar bundle structure, and MWNTs in the composite tended to align parallel to the drawing direction. In addition, the dispersion of MWNTs in PLA was also improved by orientation. Introduction of MWNTs and drawing orientation could significantly enhance the blood compatibility of PLA by prolonging kinetic clotting time, reducing hemolysis ratio and platelet activation.

  15. Specific and Efficient Uptake of Surfactant-Free Poly(Lactic Acid) Nanovaccine Vehicles by Mucosal Dendritic Cells in Adult Zebrafish after Bath Immersion

    PubMed Central

    Rességuier, Julien; Delaune, Emilie; Coolen, Anne-Line; Levraud, Jean-Pierre; Boudinot, Pierre; Le Guellec, Dominique; Verrier, Bernard

    2017-01-01

    Activation of mucosal immunity is a key milestone for next-generation vaccine development. Biocompatible polymer-based nanoparticles (NPs) are promising vectors and adjuvants for mucosal vaccination. However, their in vivo uptake by mucosae and their biodistribution in antigen-presenting cells (APCs) need to be better understood to optimize mucosal nanovaccine designs. Here, we assessed if APCs are efficiently targeted in a spontaneous manner by surfactant-free poly(lactic acid) nanoparticles (PLA-NPs) after mucosal administration. Combining histology and flow imaging approaches, we describe and quantify the mucosal uptake of 200 nm PLA-NPs in adult zebrafish. Following bath administration, PLA-NPs penetrated and crossed epithelial barriers from all exposed mucosae. In mucosae, PLA-NPs accumulated in APCs, which were identified as dendritic cells (DCs), macrophages, and IgZ+ B cells in gills and skin. PLA-NP uptake by phagocytes was specific to these cell types, as PLA-NPs were not detected in neutrophils. Importantly, quantitative analyses in gills revealed that DCs take up PLA-NPs with specifically high efficiency. This study shows that surfactant-free PLA-NPs, which display optimal biocompatibility, can spontaneously target DCs with high efficiency in vivo following mucosal administration, and highlights PLA-NPs as powerful platforms for mucosal vaccine delivery in the medical and veterinary fields, and particularly in aquaculture. PMID:28289416

  16. Electrohydrodynamic quenching in polymer melt electrospinning

    NASA Astrophysics Data System (ADS)

    Zhmayev, Eduard; Cho, Daehwan; Lak Joo, Yong

    2011-07-01

    Infrared thermal measurements on polymer melt jets in electrospinning have revealed rapid quenching by ambient air, an order of magnitude faster than predicted by the classical Kase and Matsuo correlation. This drastic heat transfer enhancement can be linked to electrohydrodynamic (EHD) effects. Analysis of EHD-driven air flow was performed and included into a comprehensive model for polymer melt electrospinning. The analysis was validated by excellent agreement of both predicted jet radius and temperature profiles with experimental results for electrospinning of Nylon-6 (N6), polypropylene (PP), and polylactic acid (PLA) melts. Based on this analysis, several methods that can be used to inhibit or enhance the quenching are described.

  17. 40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... aliphatic polyol dihydrogen phosphate aromatic ester (generic). 721.10289 Section 721.10289 Protection of... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject...

  18. 40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... aliphatic polyol dihydrogen phosphate aromatic ester (generic). 721.10289 Section 721.10289 Protection of... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject...

  19. Identification of important abiotic and biotic factors in the biodegradation of poly(l-lactic acid).

    PubMed

    Husárová, Lucie; Pekařová, Silvie; Stloukal, Petr; Kucharzcyk, Pavel; Verney, Vincent; Commereuc, Sophie; Ramone, Audrey; Koutny, Marek

    2014-11-01

    The biodegradation of four poly(l-lactic acid) (PLA) samples with molecular weights (MW) ranging from approximately 34 to 160kgmol(-1) was investigated under composting conditions. The biodegradation rate decreased, and initial retardation was discernible in parallel with the increasing MW of the polymer. Furthermore, the specific surface area of the polymer sample was identified as the important factor accelerating biodegradation. Microbial community compositions and dynamics during the biodegradation of different PLA were monitored by temperature gradient gel electrophoresis, and were found to be virtually identical for all PLA materials and independent of MW. A specific PLA degrading bacteria was isolated and tentatively designated Thermopolyspora flexuosa FTPLA. The addition of a limited amount of low MW PLA did not accelerate the biodegradation of high MW PLA, suggesting that the process is not limited to the number of specific degraders and/or the induction of specific enzymes. In parallel, abiotic hydrolysis was investigated for the same set of samples and their courses found to be quasi-identical with the biodegradation of all four PLA samples investigated. This suggests that the abiotic hydrolysis represented a rate limiting step in the biodegradation process and the organisms present were not able to accelerate depolymerization significantly by the action of their enzymes.

  20. Mechanical, thermal and morphological properties of poly(lactic acid)/epoxidized palm olein blend.

    PubMed

    Silverajah, V S Giita; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Yunus, Wan Md Zin Wan; Hassan, Hazimah Abu

    2012-10-08

    Poly(lactic acid) (PLA) is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO) was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt%) through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM) analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered.

  1. Transient Current Behaviour of Poly (p-hydroxybenzoic acid-co-ethylene terephthalate) Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Yarramaneni, Sridharbabu; Sharma, Anu; Quamara, J. K.

    2011-07-01

    Transient current behaviour of pristine Poly (p-hydroxybenzoic acid-co-ethylene terephthalate) Liquid crystal polymer which is a copolymer of poly ethylene terephthalate and poly p-hydroxybenzoic acid referred as PET/x.PHB polymer liquid crystals have been studied at different biasing electric fields ranging from 13 kV/cm to 104.3 kV/cm and at temperatures 120° C and 250° C for molar ratio x =0.8.

  2. Clinical Performance of a Dermal Filler Containing Natural Glycolic Acid and a Polylactic Acid Polymer

    PubMed Central

    Macchetto, Pedro Cervantes; Durán Páramo, Rosa Margarita

    2010-01-01

    Lipoatrophy is a condition that affects certain individuals, most commonly those who are infected with the human immunodeficiency virus.1–3 Injectable fillers are used for the treatment of these dermal contour deformities to smooth dermal depressions formed by the loss of volume. These dermal fillers (also known as soft tissue augmentation devices) can correct contour deformities caused by lipoatrophy in patients who are human immunodeficiency virus positive or negative. The product used in this study is a patented, second-generation, injectable, dermal collagen stimulator that combines glycolic acid and polylactic acid. The glycolic acid used is not a polymer, but rather an acid derived from sugar cane. Its chemical structure corresponds to that of an alpha-hydroxy acid. Glycolic acid is a well-characterized agent that is present in a number of cosmetic products. Polylactic acid is a synthetic, biocompatible, biodegradable, inert, synthetic polymer from the poly a-hydroxy-acid family that is believed to stimulate fibroblasts to produce more collagen, thus increasing facial volume. Together, polylactic acid and glycolic acid act in concert to 1) stimulate collagen production and 2) hydrate the outer layers of the skin. A multicenter, clinical investigation authorized by the Mexican Secretariat of Health was conducted between September 20, 2002, and September 19, 2004. This clinical study was conducted in male patients between 32 and 60 years of age with lipoatrophy as a result of highly active antiretroviral therapy for human immunodeficiency virus infection. The study objective was to measure the improvement of contour deformities after the injection of a dermal collagen stimulator containing glycolic acid and polylactic acid. In addition to safety, this dermal filler was assessed when used to correct volume deformities caused by lipoatrophy in subjects who are human immunodeficiency virus positive. Thirty male subjects participated and were treated as follows

  3. Main chain acid-degradable polymers for the delivery of bioactive materials

    DOEpatents

    Frechet, Jean M. J. [Oakland, CA; Standley, Stephany M [Evanston, IL; Jain, Rachna [Milpitas, CA; Lee, Cameron C [Cambridge, MA

    2012-03-20

    Novel main chain acid degradable polymer backbones and drug delivery systems comprised of materials capable of delivering bioactive materials to cells for use as vaccines or other therapeutic agents are described. The polymers are synthesized using monomers that contain acid-degradable linkages cleavable under mild acidic conditions. The main chain of the resulting polymers readily degrade into many small molecules at low pH, but remain relatively stable and intact at physiological pH. The new materials have the common characteristic of being able to degrade by acid hydrolysis under conditions commonly found within the endosomal or lysosomal compartments of cells thereby releasing their payload within the cell. The materials can also be used for the delivery of therapeutics to the acidic regions of tumors and other sites of inflammation.

  4. Soluble polymer supported synthesis of alpha-amino acid derivatives.

    PubMed

    Sauvagnat, B; Kulig, K; Lamaty, F; Lazaro, R; Martinez, J

    2000-01-01

    A Schiff base activated glycine supported on a soluble polymer (poly(ethylene glycol) (PEG)) was readily alkylated with a wide variety of electrophiles in the presence of a carbonate base in acetonitrile. The presence of the polymer provided a phase-transfer catalysis environment which accelerated the reaction. Effects of various carbonate bases and leaving groups have been also studied. Completion of the PEG-supported reaction was obtained without using a large excess of reagents or an extra phase-transfer catalyst, even in the case of unreactive or hindered electrophiles. After cleavage from the polymer, alpha-amino esters are obtained in good yields.

  5. PLA/CS/Nifedipine Nanocomposite Films: Properties and the In Vitro Release of Nifedipine

    NASA Astrophysics Data System (ADS)

    Trang, Nguyen Thi Thu; Chinh, Nguyen Thuy; Giang, Nguyen Vu; Thanh, Dinh Thi Mai; Lam, Tran Dai; Hoang, Thai

    2016-07-01

    The polylactic acid (PLA)/chitosan (CS) films containing a drug, nifedipine (NIF), in the presence of polyethylene oxide (PEO) as a compatibilizer were prepared by the solution method. This method has not been used to form films containing four components (PLA, CS, NIF, PEO) up to now. The CS, PEO, and NIF contents are 25 wt.%, 6-8 wt.%, and 10-50 wt.% in comparison with PLA weight, respectively. Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FESEM) were used to characterize the interactions, properties, and morphology of the PLA/CS/PEO/NIF films. The FTIR, TGA, and DSC results show that NIF carried by PLA/CS/PEO films and PLA, CS, NIF had better interaction and were more compatible when using PEO. The surface morphology of PLA/CS/PEO/NIF films was similar to that of PLA/CS/PEO films. Moreover, this was the first time drug loading and NIF release content from PLA/CS/PEO films were determined by the ultraviolet-visible (UV-Vis) spectroscopy method. The drug loading of PLA/CS/PEO/NIF films was from 80.99% to 93.61%. The in vitro NIF release studies were carried out in pH 2, 6.8, and 7.4 solutions corresponding to the pH of stomach, colon, and duodenum regions in the human body, respectively. The NIF release content in different pH solutions is in the order: pH 2 > pH 6.8 > pH 7.4 and increases when there is increasing NIF loading. The PLA/CS/PEO films are potential materials to apply for long-circulating systems for NIF delivery.

  6. Lactide Synthesis and Chirality Control for Polylactic acid Production.

    PubMed

    Van Wouwe, Pieter; Dusselier, Michiel; Vanleeuw, Evelien; Sels, Bert

    2016-05-10

    Polylactic acid (PLA) is a very promising biodegradable, renewable, and biocompatible polymer. Aside from its production, its application field is also increasing, with use not only in commodity applications but also as durables and in biomedicine. In the current PLA production scheme, the most expensive part is not the polymerization itself but obtaining the building blocks lactic acid (LA) and lactide, the actual cyclic monomer for polymerization. Although the synthesis of LA and the polymerization have been studied systematically, reports of lactide synthesis are scarce. Most lactide synthesis methods are described in patent literature, and current energy-intensive, aselective industrial processes are based on archaic scientific literature. This Review, therefore, highlights new methods with a technical comparison and description of the different approaches. Water-removal methodologies are compared, as this is a crucial factor in PLA production. Apart from the synthesis of lactide, this Review also emphasizes the use of chemically produced racemic lactic acid (esters) as a starting point in the PLA production scheme. Stereochemically tailored PLA can be produced according to such a strategy, giving access to various polymer properties.

  7. Bionanocomposite films based on plasticized PLA-PHB/cellulose nanocrystal blends.

    PubMed

    Arrieta, M P; Fortunati, E; Dominici, F; López, J; Kenny, J M

    2015-05-05

    Optically transparent plasticized poly(lactic acid) (PLA) based bionanocomposite films intended for food packaging were prepared by melt blending. Materials were plasticized with 15wt% of acetyl(tributyl citrate) (ATBC) to improve the material processability and to obtain flexibile films. Poly(hydroxybutyrate) (PHB) was used to increase PLA crystallinity. The thermal stability of the PLA-PHB blends was improved by the addition of 5 wt% of cellulose nanocrystals (CNC) or modified cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose. The combination of ATBC and cellulose nanocrystals, mainly the better dispersed CNCs, improved the interaction between PLA and PHB. Thus, an improvement on the oxygen barrier and stretchability was achieved in PLA-PHB-CNCs-ATBC which also displayed somewhat UV light blocking effect. All bionanocomposite films presented appropriate disintegration in compost suggesting their possible applications as biodegradable packaging materials.

  8. Effect of diameter of poly(lactic acid) fiber on the physical properties of poly(ɛ-caprolactone).

    PubMed

    Ju, Dandan; Han, Lijing; Guo, Ziqi; Bian, Junjia; Li, Fan; Chen, Shan; Dong, Lisong

    2015-05-01

    Biodegradable polymer composites based on poly(ɛ-caprolactone) (PCL) and poly(lactic acid) (PLA) fibers with diameters of 18, 26, 180 μm were prepared by melt compounding. The PLA fiber content in the composites was constant at 20% by weight. The effects of fibers with different diameters on the physical properties and enzymatic degradation of PCL were investigated. The morphological analysis indicated good interfacial adhesion between PCL and PLA fiber, which was beneficial to improve the physical properties of PCL. With increasing PLA fiber diameter, the complex viscosity and modulus of PCL were significantly increased, especially at low frequencies, indicating that the hindered effect of the fiber on the mobility of the PCL molecular chains was more obvious when PLA fiber diameter was thicker. However, as for the mechanical properties, the reinforcement was more obvious to PCL with the smaller PLA fiber diameter. This was because increasing efficient load transfer may be appeared due to the larger surface area and better interface bonding force of the fiber with thinner diameters. The enzymatic degradation of PCL was accelerated with the addition of large PLA fiber diameter of 26 and 180 μm, and hardly changed with the small PLA fiber diameter of 18 μm.

  9. [Development of new skin substitutes based on bioresorbable polymer for treatment of severe skin defects].

    PubMed

    Garric, X; Vert, M; Molès, J-P

    2008-01-01

    Over the last years, increasing attention has been paid to skin engineering due to its predominant function in body integrity. Thus, many laboratories are attempting to develop a dermal-epidermal complex. The aim of this study was to evaluate the potential of poly(alpha-hydroxyacid)s in the development of biocompatible and bioresorbable dermal scaffold combining human fibroblasts and keratinocytes, in order to obviate the drawbacks of using natural polymers such as collagen, hyaluronic acid and fibrin. We first confirmed the interest of poly(d,l-lactic acid) (PLA(50)) during the reconstitution of epidermis and next, we investigated the potential of poly(d,l-lactic acid)-poly(ethylene glycol)-poly(d,l-lactic acid) (PLA(50)-PEG-PLA(50)) for either skin cytocompatibility or scaffold processing. Data showed that PLA(50)-PEG-PLA(50) is compatible with the culture of human skin cells (fibroblasts and keratinocytes) and the development of a porous scaffold; two requirements compulsory for being considered as an adequate skin substitute. In fine, this material could represent the first generation of new skin dressings, i.e. a new concept taking advantage of both implantable devices and current dressings.

  10. Effect of hydrolysed cellulose nanowhiskers on properties of montmorillonite/polylactic acid nanocomposites.

    PubMed

    Arjmandi, Reza; Hassan, Azman; Haafiz, M K M; Zakaria, Zainoha; Islam, Md Saiful

    2016-01-01

    Polylactic acid (PLA) nanocomposites reinforced with hybrid montmorillonite/cellulose nanowhiskers [MMT/CNW(SO4)] were prepared by solution casting. The CNW(SO4) nanofiller was first isolated from microcrystalline cellulose using acid hydrolysis treatment. PLA/MMT/CNW(SO4) hybrid nanocomposites were prepared by the addition of various amounts of CNW(SO4) [1-9 parts per hundred parts of polymer (phr)] into PLA/MMT nanocomposite at 5 phr MMT content, based on highest tensile strength values as reported previously. The biodegradability, thermal, tensile, morphological, water absorption and transparency properties of PLA/MMT/CNW(SO4) hybrid nanocomposites were investigated. The Biodegradability, thermal stability and crystallinity of hybrid nanocomposites increased compared to PLA/MMT nanocomposite and neat PLA. The highest tensile strength of hybrid nanocomposites was obtained by incorporating 1 phr CNW(SO4) [∼ 36 MPa]. Interestingly, the ductility of hybrid nanocomposites increased significantly by 87% at this formulation. The Young's modulus increased linearly with increasing CNW(SO4) content. This is due to the relatively good dispersion of nanofillers in the hybrid nanocomposites, as revealed by transmission electron microscopy. Fourier transform infrared spectroscopy indicated the formation of some polar interactions. In addition, water resistance of the hybrid nanocomposites improved and the visual transparency of neat PLA film did not affect by addition of CNW(SO4).

  11. Fabrication of novel PLA/CDHA bionanocomposite fibers for tissue engineering applications via electrospinning.

    PubMed

    Zhou, Huan; Touny, Ahmed H; Bhaduri, Sarit B

    2011-05-01

    The main theme here is to fabricate PLA (poly lactic-acid)/CDHA (carbonated calcium deficient hydroxyapatite) bionanocomposites, where both the constituents are biocompatible and biodegradable with one dimension in nanometer scale. Such materials are important in tissue engineering applications. The bionanocomposite fibers were fabricated via electrospinning. There are two important signatures of this paper. First, CDHA, rather than HA, is added to PLA as the second phase. As opposed to HA, CDHA mimics the bone mineral composition better and is biodegradable. Therefore, PLA/CDHA fibers should have better biodegradability while maintaining a physiological pH during degradation. To the best of our knowledge, this is the first attempt of electrospinning of such a composite. Second, the CDHA nanoparticles were synthesized using the benign low temperature biomimetic technique, the only route available for the retention of carbonate ions in the HA lattice. The structural properties, degradation behavior, bioactivity, cell adhesion, and growth capability of as-fabricated PLA/CDHA bionanocomposites were investigated. The results show that the incorporation of CDHA decreased PLA fiber diameters, accelerated PLA degradation, buffered pH decrease caused by PLA degradation, improved the bioactivity and biocompatibility of the scaffold. These results prove that PLA/CDHA bionanocomposites have the potential in tissue regeneration applications.

  12. Loss of PLA2G6 leads to elevated mitochondrial lipid peroxidation and mitochondrial dysfunction

    PubMed Central

    Castillo-Quan, Jorge Iván; Bartolome, Fernando; Angelova, Plamena R.; Li, Li; Pope, Simon; Cochemé, Helena M.; Khan, Shabana; Asghari, Shabnam; Bhatia, Kailash P.; Hardy, John; Abramov, Andrey Y.; Partridge, Linda

    2015-01-01

    The PLA2G6 gene encodes a group VIA calcium-independent phospholipase A2 beta enzyme that selectively hydrolyses glycerophospholipids to release free fatty acids. Mutations in PLA2G6 have been associated with disorders such as infantile neuroaxonal dystrophy, neurodegeneration with brain iron accumulation type II and Karak syndrome. More recently, PLA2G6 was identified as the causative gene in a subgroup of patients with autosomal recessive early-onset dystonia-parkinsonism. Neuropathological examination revealed widespread Lewy body pathology and the accumulation of hyperphosphorylated tau, supporting a link between PLA2G6 mutations and parkinsonian disorders. Here we show that knockout of the Drosophila homologue of the PLA2G6 gene, iPLA2-VIA, results in reduced survival, locomotor deficits and organismal hypersensitivity to oxidative stress. Furthermore, we demonstrate that loss of iPLA2-VIA function leads to a number of mitochondrial abnormalities, including mitochondrial respiratory chain dysfunction, reduced ATP synthesis and abnormal mitochondrial morphology. Moreover, we show that loss of iPLA2-VIA is strongly associated with increased lipid peroxidation levels. We confirmed our findings using cultured fibroblasts taken from two patients with mutations in the PLA2G6 gene. Similar abnormalities were seen including elevated mitochondrial lipid peroxidation and mitochondrial membrane defects, as well as raised levels of cytoplasmic and mitochondrial reactive oxygen species. Finally, we demonstrated that deuterated polyunsaturated fatty acids, which inhibit lipid peroxidation, were able to partially rescue the locomotor abnormalities seen in aged flies lacking iPLA2-VIA gene function, and restore mitochondrial membrane potential in fibroblasts from patients with PLA2G6 mutations. Taken together, our findings demonstrate that loss of normal PLA2G6 gene activity leads to lipid peroxidation, mitochondrial dysfunction and subsequent mitochondrial membrane

  13. Nanocomposite polymer electrolyte based on Poly(ethylene oxide) and solid super acid for lithium polymer battery

    NASA Astrophysics Data System (ADS)

    Xi, Jingyu; Tang, Xiaozhen

    2004-07-01

    This Letter reports a novel PEO-based nanocomposite polymer electrolyte by using solid super acid SO 42-/ZrO 2 as filler. XRD, DSC, and FT-IR results prove the strong Lewis acid-base interactions between SO 42-/ZrO 2 and PEO chains. The addition of SO 42-/ZrO 2 can enhance the ionic conductivity and the lithium ion transference number of the electrolyte. The highest room temperature ionic conductivity of 2.1 × 10 -5 S cm -1 is obtained for the sample PEO 12-LiClO 4-7%SO 42-/ZrO 2. The excellent performances such as good compatibility with lithium electrode, and broad electrochemical stability window suggest that PEO-LiClO 4-SO 42-/ZrO 2 nanocomposite electrolyte can be used as electrolyte materials for lithium polymer batteries.

  14. Production and characterization of thermoplastic cassava starch, functionalized poly(lactic acid), and their reactive compatibilized blends

    NASA Astrophysics Data System (ADS)

    Detyothin, Sukeewan

    Cassava starch was blended with glycerol using a co-rotating twin-screw extruder (TSE). Thermoplastic cassava starch (TPCS) at a ratio of 70/30 by weight of cassava/glycerol was selected and further blended with other polymers. TPCS sheets made from compression molding had low tensile strength (0.45 +/- 0.05 MPa) and Young's modulus (1.24 +/- 0.58 MPa), but moderate elongation at break (83.0 +/- 0.18.6%), medium level of oxygen permeability, and high water vapor permeability with a very high rate of water absorption. TPCS was blended with poly(lactic acid) (PLA) at various ratios by using a TSE. The blend resins exhibited good properties such as increased thermal stability (Tmax) and crystallinity of PLA, and improved water sensitivity and processability of TPCS. PLA and TPCS exhibited a high interfacial tension between the two phases of 7.9 mJ·m -2, indicating the formation of an incompatible, immiscible blend. SEM micrographs showed a non-homogeneous distribution of TPCS droplets in the PLA continuous phase. TEM micrographs of the blend films made by cast-film extrusion showed coalescence of the TPCS droplets in the PLA continuous phase of the blend, indicating that the compatibility between the polymer pair needs to be improved. A response surface methodology (RSM) design was used to analyze the effects of maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox or L101) contents, and TSE screw speed on the degree of grafted MA and number average molecular weight (Mn) of functionalized PLA (PLA-g-MA), a reactive compatibilizer. PLA-g- MA made by reactive extrusion had an array of colors depending on the content of L101 and MA used. New FTIR peaks suggested that MA was grafted onto the PLA backbone and oligomeric MA may occur. Increasing L101 increased the degree of grafting and decreased Mn, but the Mn of the PLA-g-MA's produced with a high amount of L101 was stable during storage. MA exhibited an optimum concentration for maximizing the

  15. Uncertainty in the Life Cycle Greenhouse Gas Emissions from U.S. Production of Three Biobased Polymer Families.

    PubMed

    Posen, I Daniel; Jaramillo, Paulina; Griffin, W Michael

    2016-03-15

    Interest in biobased products has been motivated, in part, by the claim that these products have lower life cycle greenhouse gas (GHG) emissions than their fossil counterparts. This study investigates GHG emissions from U.S. production of three important biobased polymer families: polylactic acid (PLA), polyhydroxybutyrate (PHB) and bioethylene-based plastics. The model incorporates uncertainty into the life cycle emission estimates using Monte Carlo simulation. Results present a range of scenarios for feedstock choice (corn or switchgrass), treatment of coproducts, data sources, end of life assumptions, and displaced fossil polymer. Switchgrass pathways generally have lower emissions than corn pathways, and can even generate negative cradle-to-gate emissions if unfermented residues are used to coproduce energy. PHB (from either feedstock) is unlikely to have lower emissions than fossil polymers once end of life emissions are included. PLA generally has the lowest emissions when compared to high emission fossil polymers, such as polystyrene (mean GHG savings up to 1.4 kg CO2e/kg corn PLA and 2.9 kg CO2e/kg switchgrass PLA). In contrast, bioethylene is likely to achieve the greater emission reduction for ethylene intensive polymers, like polyethylene (mean GHG savings up to 0.60 kg CO2e/kg corn polyethylene and 3.4 kg CO2e/kg switchgrass polyethylene).

  16. Molecular dynamics simulations on the interaction between polymers and hydroxyapatite with and without coupling agents.

    PubMed

    Zhang, Hong-ping; Lu, Xiong; Leng, Yang; Fang, Liming; Qu, Shuxin; Feng, Bo; Weng, Jie; Wang, Jianxin

    2009-05-01

    Molecular dynamics (MD) simulations were employed to study hydroxyapatite/biopolymer interface interactions in composites for biomedical applications. The study analyzed the binding energies between hydroxyapatite (HA) and three polymers: polyethylene (PE), polyamide (PA) and polylactic acid (PLA). The interactions of polymers on HA crystallographic planes (001), (100) and (110) were simulated. The effects of the silane coupling agent (A174) on interfacial binding energies were also examined. The results show that HA (110) has the highest binding energy with these polymers because of its higher planar atom density than that of HA (001) and (100). The binding energies of PA/HA and PLA/HA are much higher than that of PE/HA, which might be attributed to large number of polar groups in PA and PLA chains. The silane coupling agent A174 increases the binding energy between PE and HA, but not for the PA/HA and PLA/HA systems. The MD results can be used to guide the design of polymer/HA composites and to select proper coupling agents.

  17. Synthesis of homoveratric acid-imprinted polymers and their evaluation as selective separation materials.

    PubMed

    Dana, Mariusz; Luliński, Piotr; Maciejewska, Dorota

    2011-05-05

    A bulk polymerization method was used to easily and efficiently prepare homoveratric acid (3,4-dimethoxyphenylacetic acid)-imprinted polymers from eight basic monomers: 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, N-allylaniline, N-allylpiperazine, allylurea, allylthiourea, and allylamine, in the presence of homoveratric acid as a template in N,N-dimethylformamide as a porogen. The imprinted polymer prepared from allylamine had the highest affinity to the template, showing an imprinting factor of 3.43, and allylamine polymers MIP8/NIP8 were selected for further studies. Their binding properties were analyzed using the Scatchard method. The results showed that the imprinted polymers have two classes of heterogeneous binding sites characterized by two pairs of K(d), B(max) values: K(d)(1) = 0.060 μmol/mL, B(max)(1) = 0.093 μmol/mg for the higher affinity binding sites, and K(d)(2) = 0.455 μmol/mL, B(max)(2) = 0.248 μmol/mg for the lower affinity binding sites. Non-imprinted polymer has only one class of binding site, with K(d) = 0.417 μmol/mL and B(max) = 0.184 μmol/mg. A computational analysis of the energies of the prepolymerization complexes was in agreement with the experimental results. It showed that the selective binding interactions arose from cooperative three point interactions between the carboxylic acid and the two methoxy groups in the template and amino groups in the polymer cavities. Those results were confirmed by the recognition studies performed with the set of structurally related compounds. Allylamine polymer MIP8 had no affinity towards biogenic amines. The obtained imprinted polymer could be used for selective separation of homoveratric acid.

  18. Biodegradable Photo-Crosslinked Thin Polymer Networks Based on Vegetable Oil Hydroxyfatty Acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel crosslinked thin polymer networks based on vegetable oil hydroxyfatty acids (HFAs) were prepared by UV photopolymerization and their mechanical properties were evaluated. Two raw materials, castor oil and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) were used as sources of mono- and di-HFAs, r...

  19. Effects of Acid and Ionic Aggregation on the Polymer Dynamics in Precise Ionomers

    NASA Astrophysics Data System (ADS)

    Middleton, Luri Robert; Tarver, Jacob; Azoulay, Jason; Murtagh, Dustin; Wagener, Ken; Cordaro, Joseph; Tyagi, Madhu; Soles, Christopher; Winey, Karen

    2015-03-01

    Interest in acid- and ion-containing polymers arises from applications as single-ion conductors for selectively transporting a counter ion of the opposite charge for energy applications. The relatively low dielectric constant of the organic polymer and strong ionic interactions leads to ionic aggregation. Ion aggregation anchors the polymer chain, decreasing the mobility of the ion and the polymer. In precise poly(ethylene-acrylic acid) copolymers and ionomers (pxAA-%Li) we report on the effect of carbon spacer length (x =9, 15, 21) between the acid groups and the effect of the percent of acid groups neutralized with Li on backbone dynamics. The polymer backbone motion is investigated through quasi-elastic neutron scattering measurements. At nano-second timescales a single relaxation fits the data. Systematic changes in dynamics were observed with increasing neutralization percent where polymer dynamics are confined due to anchoring effects. Intriguingly, systematic changes in the spacer lengths did not result in similar behavior. At pico-second timescales multiple overlapping relaxations are observed but even at these short timescales systematic changes in atomic motion are observed with ion content. NSF-DMR-1103858.

  20. Responsive Boronic Acid-Decorated (Co)polymers: From Glucose Sensors to Autonomous Drug Delivery

    PubMed Central

    Vancoillie, Gertjan; Hoogenboom, Richard

    2016-01-01

    Boronic acid-containing (co)polymers have fascinated researchers for decades, garnering attention for their unique responsiveness toward 1,2- and 1,3-diols, including saccharides and nucleotides. The applications of materials that exert this property are manifold including sensing, but also self-regulated drug delivery systems through responsive membranes or micelles. In this review, some of the main applications of boronic acid containing (co)polymers are discussed focusing on the role of the boronic acid group in the response mechanism. We hope that this summary, which highlights the importance and potential of boronic acid-decorated polymeric materials, will inspire further research within this interesting field of responsive polymers and polymeric materials. PMID:27775572

  1. Poly(lactic acid) and Osage Orange Wood Fiber Composites for Agricultural Mulch Films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Osage orange wood was combined with poly(lactic acid) to form a polymer composite intendedfor use as an agricultural mulch film. The mechanical properties were comparable to existing products and had the advantage of being completely biodegradable through a single growing season. PLA-OO composites...

  2. New biocomposites based on bioplastic flax fibers and biodegradable polymers.

    PubMed

    Wróbel-Kwiatkowska, Magdalena; Czemplik, Magdalena; Kulma, Anna; Zuk, Magdalena; Kaczmar, Jacek; Dymińska, Lucyna; Hanuza, Jerzy; Ptak, Maciej; Szopa, Jan

    2012-01-01

    A new generation of entirely biodegradable and bioactive composites with polylactic acid (PLA) or poly-ε-caprolactone (PCL) as the matrix and bioplastic flax fibers as reinforcement were analyzed. Bioplastic fibers contain polyhydroxybutyrate and were obtained from transgenic flax. Biochemical analysis of fibers revealed presence of several antioxidative compounds of hydrophilic (phenolics) and hydrophobic [cannabidiol (CBD), lutein] nature, indicating their high antioxidant potential. The presence of CBD and lutein in flax fibers is reported for the first time. FTIR analysis showed intermolecular hydrogen bonds between the constituents in composite PLA+flax fibers which were not detected in PCL-based composite. Mechanical analysis of prepared composites revealed improved stiffness and a decrease in tensile strength. The viability of human dermal fibroblasts on the surface of composites made of PLA and transgenic flax fibers was the same as for cells cultured without composites and only slightly lower (to 9%) for PCL-based composites. The amount of platelets and Escherichia coli cells aggregated on the surface of the PLA based composites was significantly lower than for pure polymer. Thus, composites made of PLA and transgenic flax fibers seem to have bacteriostatic, platelet anti-aggregated, and non-cytotoxic effect.

  3. Preparation of biodegradable PLA/PLGA membranes with PGA mesh and their application for periodontal guided tissue regeneration.

    PubMed

    Kim, Eun Jin; Yoon, Suk Joon; Yeo, Guw-Dong; Pai, Chaul-Min; Kang, Inn-Kyu

    2009-10-01

    A biodegradable polylactic acid (PLA)/poly(glycolide-co-lactide) copolymer (PLGA) membrane with polyglycolic acid (PGA) mesh was prepared to aid the effective regeneration of defective periodontal tissues. The microporous membrane used in this study consists of biodegradable polymers, and seems to have a structure to provide appropriate properties for periodontal tissue regeneration. Based on the albumin permeation test, it is known that the biodegradable membrane exhibits the suitable permeability of nutrients. The membrane maintained its physical integrity for 6-8 weeks, which could be sufficient to retain space in the periodontal pocket. Cell attachment and cytotoxicity tests were performed with respect to the evaluation of biocompatibility of the membrane. As a result, the membrane did not show any cytotoxicity. The safety and therapeutic efficacies of the biodegradable membranes were confirmed in animal tests.

  4. P9a(Cdt-PLA2) from Crotalus durissus terrificus as good immunogen to be employed in the production of crotalic anti-PLA2 IgG.

    PubMed

    Fusco, Luciano S; Rodríguez, Juan Pablo; Torres-Huaco, Frank; Huancahuire-Vega, Salomón; Teibler, Pamela; Acosta, Ofelia; Marangoni, Sergio; Ponce-Soto, Luis Alberto; Leiva, Laura C

    2015-10-01

    Four proteins with phospholipase A2 (PLA2) activity, designated P9a(Cdt-PLA2), P9b(Cdt-PLA2), P10a(Cdt-PLA2) and P10b(Cdt-PLA2) were purified from the venom of Crotalus durissus terrificus by two chromatographic steps: a gel filtration and reversed phase HPLC. The profile obtained clearly shows that three of them have a similar abundance. The molecular mass, 14193.8340Da for P9a(Cdt-PLA2), 14134.9102Da for P9b(Cdt-PLA2), 14242.6289Da for P10a(Cdt-PLA2) and 14183.8730Da for P10b(Cdt-PLA2), were initially evaluated by SDS-PAGE and confirmed by ESI-Q-TOF spectrometry, and all of them displayed a monomeric conformation. Also, partial amino acid sequence of each protein was obtained and their alignments with other crotalic PLA2 revealed a high degree of identity among them. Additionally, we studied some pharmacological activities like neurotoxicity, myotoxicity and lethality, which prompted us to pick two of them, P9a(Cdt-PLA2) and P10a(Cdt-PLA2) that resulted to be less toxic that the others, and further characterize them to be used as immunogen. We next injected these last proteins in mice to produce antitoxins against them and ELISA and dot blots reveled that both toxins do not show immunogenic differences, unlike those other pharmacologic activities tested. Furthermore, the antibodies produced cross-reacted with all the isoforms purified demonstrating the feasibility of using only one of them and ensuring the cross-reaction of all. The results obtained show that P9a(Cdt-PLA2) isoform has the lowest toxicity and also a good purification performance; thus this protein may be a promising candidate to be employed in the production of crotalic antitoxins.

  5. Water soluble and heat resistant polymers by free radical polymerization of lactic acid-based monomers

    NASA Astrophysics Data System (ADS)

    Tanaka, Hitoshi; Kibayashi, Tatsuya; Niwa, Miki

    2013-08-01

    Tactic heat resistant polymer was prepared by free radical polymerization of lactic acid-based monomers, i.e. chiral 2-isopropyl-5-methylene-1,3-dioxolan-4-ones (1). The polymerization of 1 proceeded smoothly without ring-opening to give a polymer with high isotacticity (mm) of 29.7~100% and glass transition temperature (Tg) of 172~213°C. 1 also showed high reactivity in the copolymerization with styrene and methyl methacrylate, and the incorporation of 1 unit in the copolymer structure increased Tg of each polymer. In addition, hydrolysis of poly(1) produced a new type of water soluble poly(lactic acid), i.e. poly(α-hydroxy acrylate), and poly(α-hydroxy acrylate-co-divinyl benzene) hydrogel absorbed water as high as 1000 times of the original polymer weight.

  6. Salicylic acid-releasing polyurethane acrylate polymers as anti-biofilm urological catheter coatings.

    PubMed

    Nowatzki, Paul J; Koepsel, Richard R; Stoodley, Paul; Min, Ke; Harper, Alan; Murata, Hironobu; Donfack, Joseph; Hortelano, Edwin R; Ehrlich, Garth D; Russell, Alan J

    2012-05-01

    Biofilm-associated infections are a major complication of implanted and indwelling medical devices like urological and venous catheters. They commonly persist even in the presence of an oral or intravenous antibiotic regimen, often resulting in chronic illness. We have developed a new approach to inhibiting biofilm growth on synthetic materials through controlled release of salicylic acid from a polymeric coating. Herein we report the synthesis and testing of a ultraviolet-cured polyurethane acrylate polymer composed, in part, of salicyl acrylate, which hydrolyzes upon exposure to aqueous conditions, releasing salicylic acid while leaving the polymer backbone intact. The salicylic acid release rate was tuned by adjusting the polymer composition. Anti-biofilm performance of the coatings was assessed under several biofilm forming conditions using a novel combination of the MBEC Assay™ biofilm multi-peg growth system and bioluminescence monitoring for live cell quantification. Films of the salicylic acid-releasing polymers were found to inhibit biofilm formation, as shown by bioluminescent and GFP reporter strains of Pseudomonas aeruginosa and Escherichia coli. Urinary catheters coated on their inner lumens with the salicylic acid-releasing polymer significantly reduced biofilm formation by E. coli for up to 5 days under conditions that simulated physiological urine flow.

  7. Synthesis and characterization of mPEG-PLA prodrug micelles.

    PubMed

    Hans, Meredith; Shimoni, Karin; Danino, Dganit; Siegel, Steven J; Lowman, Anthony

    2005-01-01

    Polymeric prodrugs of mPEG-PLA-haloperidol (methoxypoly(ethylene glycol)-b-poly(lactic acid)) can self-assemble into nanoscale micelle-like structures in aqueous solutions. mPEG-PLA-haloperidol was prepared and characterized using 1H and 13C NMR. The conjugation efficiency was found to be 64.8 +/- 21%. Micelles that form spontaneously upon solubilization of the mPEG-PLA and the polymeric prodrugs in water were characterized using a variety of techniques. The mPEG-PLA and prodrug micelles were found to have diameters of 28.73 +/- 1.45 and 49.67 +/- 4.29 nm, respectively, using dynamic light scattering (DLS). The micelle size and polydispersity were also evaluated with cryogenic transmission electron microscopy (cryo-TEM) and were consistent with the DLS results. Cryo-TEM and proton NMR confirmed that the micelles were spherical in shape. DLS was also used to determine the aggregation numbers of the micelles. The aggregation numbers ranged from 351 to 603. The change in aggregation number was dependent on the total drug incorporation into the micelle core. Critical micelle concentrations were determined for the various micelle/drug formulations and found to range from 3 to 14 microg/mL. Finally, drug was incorporated into the micelle core using the conjugate, free drug with a saturated aqueous phase during production, or a combination of both techniques. Drug incorporation could be increased from 3% to 20% (w/w) using the different formulations.

  8. Development and characterization of porous polypyrrole-polylactic acid electroactive polymer blends

    NASA Astrophysics Data System (ADS)

    Chan, Christine; Chan, Ellen; Naguib, Hani E.

    2009-03-01

    Conducting polymers have sparked much research interest due to their unique ability to be electrically stimulated. However, these polymers are very brittle and have poor mechanical properties. In order to improve upon its structural integrity, it can be blended with other host polymers that have better mechanical properties. These blended composites would then possess the benefits of conductive properties while having sufficient mechanical properties to be more suitable for practical applications. Polypyrrole-polylactic acid blends were processed using chemical oxidative polymerization and compression molding, followed by gas foaming and saturation techniques to create porous structures. Characterization of these porous blends included its physical, thermal, and mechanical properties.

  9. Biodegradability of injection molded bioplastic pots containing polylactic acid and poultry feather fiber.

    PubMed

    Ahn, H K; Huda, M S; Smith, M C; Mulbry, W; Schmidt, W F; Reeves, J B

    2011-04-01

    The biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 °C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was very low (13 ± 3%) compared to literature values for other PLA materials. Near infrared spectroscopy (NIRS) results suggest that the PLA undergoes chemical structural changes during polymer extrusion and injection molding. These changes may be the basis of the low biodegradability value. Biodegradability of pot types B (containing 5% poultry feather, 80% PLA, 15% starch), and C (containing 50% poultry feather, 25% urea, 25% glycerol), were 53 ± 2% and 39 ± 3%, respectively. More than 85% of the total biodegradation of these bioplastics occurred within 38 days. NIRS results revealed that poultry feather was not degraded during composting.

  10. Preparation of flexible PLA/PEG-POSS nanocomposites by melt blending and radiation crosslinking

    NASA Astrophysics Data System (ADS)

    Jung, Chang-Hee; Hwang, In-Tae; Jung, Chan-Hee; Choi, Jae-Hak

    2014-09-01

    In this study, poly(lactic acid) (PLA)/poly(ethylene glycol)-functionalized polyhedral oligomeric silsesquioxane (PEG-POSS) nanocomposites with or without triallyl isocyanurate (TAIC) were investigated by melt blending and electron beam irradiation to enhance the flexibility of PLA. Based on the results of the crosslinking degree measurements, the PLA/PEG-POSS nanocomposites were crosslinked by electron beam irradiation in the presence of triallyl isocyanurate (TAIC) and their crosslinking degree reached up to 80% based on the absorbed dose and their compositions. From the results of the FE-SEM and EDX Si-mapping, the crosslinked PLA/PEG-POSS nanocomposites were homogenous without a micro-phase separation or radiation-induced morphological change. Based on the results of the tensile test, the PLA/PEG-POSS nanocomposites containing 15 wt% PEG-POSS exhibited the highest flexibility, and their tensile strength showed a maximum value of 44.5 MPa after electron beam irradiation at an absorbed dose of 100 kGy in the presence of TAIC, which is comparable to non-biodegradable polypropylene. The results of the dynamic mechanical analysis revealed that the crosslinked PLA/PEG-POSS nanocomposites exhibited a higher thermal resistance above their melting temperature in comparison to that of the neat PLA, although their glass transition temperature was lower than that of the neat PLA. The enzymatic biodegradation test revealed that the PLA/PEG-POSS nanocomposites were biodegradable even though their biodegradability was deteriorated in comparison to that of the neat PLA.

  11. Effect of Boric Acid on Volatile Products of Thermooxidative Degradation of Epoxy Polymers

    NASA Astrophysics Data System (ADS)

    Nazarenko, O. B.; Bukhareva, P. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The polymeric materials are characterized by high flammability. The use of flame retardants in order to reduce the flammability of polymers can lead to the formation of toxic gaseous products under fire conditions. In this work we studied the effect of boric acid on the volatile products of thermooxidative degradation of epoxy polymers. The comparative investigations were carried out on the samples of the unfilled epoxy resin and epoxy resin filled with a boric acid at percentage 10 wt. %. The analysis of the volatile decomposition products and thermal stability of the samples under heating in an oxidizing medium was performed using a thermal mass-spectrometric analysis. It is found that the incorporation of boric acid into the polymer matrix increases the thermal stability of epoxy composites and leads to a reduction in the 2-2.7 times of toxic gaseous products

  12. Heterologous expression, and biochemical and cellular characterization of CaPLA1 encoding a hot pepper phospholipase A1 homolog.

    PubMed

    Seo, Young Sam; Kim, Eun Yu; Mang, Hyung Gon; Kim, Woo Taek

    2008-03-01

    Phospholipid signaling has been recently implicated in diverse cellular processes in higher plants. We identified a cDNA encoding the phospholipase A1 homolog (CaPLA1) from 5-day-old early roots of hot pepper. The deduced amino acid sequence showed that the lipase-specific catalytic triad is well conserved in CaPLA1. In vitro lipase assays and site-directed mutagenesis revealed that CaPLA1 possesses PLA1 activity, which catalyzes the hydrolysis of phospholipids at the sn-1 position. CaPLA1 was selectively expressed in young roots, at days 4-5 after germination, and rapidly declined thereafter, suggesting that the expression of CaPLA1 is subject to control by a development-specific mechanism in roots. Because transgenic work was extremely difficult in hot peppers, in this study we overexpressed CaPLA1 in Arabidopsis so as to provide cellular information on the function of this gene. CaPLA1 overexpressors had significantly longer roots, leaves and petioles, and grew more rapidly than the wild-type plants, leading to an early bolting phenotype with prolonged inflorescence. Microscopic analysis showed that the vegetative tissues of 35S:CaPLA1 plants contained an increased number of small-sized cells, which resulted in highly populated cell layers. In addition, mRNAs for cell cycle-controlled proteins and fatty acid catabolizing enzymes were coordinately upregulated in CaPLA1-overexpressing plants. These results suggest that CaPLA1 is functionally relevant in heterologous Arabidopsis cells, and hence might participate in a subset of positive control mechanisms of cell and tissue growth in transgenic lines. We discuss possible biochemical and cellular functions of CaPLA1 in relation to the phospholipid signaling pathway in hot pepper and transgenic Arabidopsis plants.

  13. Processing-structure-properties relationships in PLA nanocomposite films

    NASA Astrophysics Data System (ADS)

    Di Maio, L.; Scarfato, P.; Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Incarnato, L.

    2014-05-01

    This work deals on the possibility to improve performances of PLA-based nanocomposite films, for packaging applications, through conveniently tuning materials and processing conditions in melt compounding technology. In particular, two types of polylactic acid and different types of filler selected from montmorillonites and bentonites families were used to prepare the hybrid systems by using a twin-screw extruder. The effect of biaxial drawing on morphology and properties of the nanocomposites, produced by film blowing, was investigated.

  14. Poly(lactic acid) filled with cassava starch-g-soybean oil maleate.

    PubMed

    Kiangkitiwan, Nopparut; Srikulkit, Kawee

    2013-01-01

    Poly(lactic acid), PLA, is a biodegradable polymer, but its applications are limited by its high cost and relatively poorer properties when compared to petroleum-based plastics. The addition of starch powder into PLA is one of the most promising efforts because starch is an abundant and cheap biopolymer. However, the challenge is the major problem associated with poor interfacial adhesion between the hydrophilic starch granules and the hydrophobic PLA, leading to poorer mechanical properties. In this paper, soybean oil maleate (SOMA) was synthesized by grafting soybean oil with various weight percents of maleic anhydride (MA) using dicumyl peroxide (DCP) as an initiator. Then, SOMA was employed for the surface modifying of cassava starch powder, resulting in SOMA-g-STARCH. The obtained SOMA-g-STARCH was mixed with PLA in various weight ratios using twin-screw extruder, resulting in PLA/SOMA-g-STARCH. Finally, the obtained PLA/SOMA-g-STARCH composites were prepared by a compression molding machines. The compatibility, thermal properties, morphology properties, and mechanical properties were characterized and evaluated. The results showed that the compatibility, surface appearance, and mechanical properties at 90 : 10 and 80 : 20 ratios of PLA/SOMA-g-STARCH were the best.

  15. A study on reactive blending of (poly lactic acid) and poly (butylene succinate co adipate)

    NASA Astrophysics Data System (ADS)

    Bureepukdee, C.; Suttiruengwong, S.; Seadan, M.

    2015-07-01

    This research aims to study the blending of Polylactic acid (PLA) and Polybutylene succinate co adipate (PBSA) in order to understand the role of peroxide in free radical reaction on the compatibilization between these two biodegradable polyesters. Various ratios of PLA/PBSA blends with and without reactive agents were prepared in the twin screw extruder. Two types of peroxides, Di (tert-butylperoxyisopropyl) benzene (DTBP) and 2, 5-Dimethyl-2, 5-(t-butylperoxy) hexane (DTBH), were used with various concentrations to compare. From the torques measurement, DTBP was more reactive with PLA and PBSA than DTBH. PLA and PBSA 80:20, 60:40, 50:50, 40:60, and 20:80% by weight were melt-blended in a twin screw extruder. The reactive polymer blends were also prepared for the same ratios of the blends with addition of 0.08 and 0.1 phr of DTBP. The mechanical, thermal, rheological, and morphological properties were investigated. The impact strengths of the non-reactive blend increased with the increasing in PBSA content. The optimal impact strength was obtained at 40%wt of PBSA with 0.1 phr of DTBP. Adding 0.08 and 0.1 phr of DTBP led to the co continuous phase morphology of PLA/PBSA blends. The per cent crystallinity of PLA increased when blended with PBSA. PBSA might induce the crystallization of PLA.

  16. Poly(Lactic Acid) Filled with Cassava Starch-g-Soybean Oil Maleate

    PubMed Central

    Kiangkitiwan, Nopparut; Srikulkit, Kawee

    2013-01-01

    Poly(lactic acid), PLA, is a biodegradable polymer, but its applications are limited by its high cost and relatively poorer properties when compared to petroleum-based plastics. The addition of starch powder into PLA is one of the most promising efforts because starch is an abundant and cheap biopolymer. However, the challenge is the major problem associated with poor interfacial adhesion between the hydrophilic starch granules and the hydrophobic PLA, leading to poorer mechanical properties. In this paper, soybean oil maleate (SOMA) was synthesized by grafting soybean oil with various weight percents of maleic anhydride (MA) using dicumyl peroxide (DCP) as an initiator. Then, SOMA was employed for the surface modifying of cassava starch powder, resulting in SOMA-g-STARCH. The obtained SOMA-g-STARCH was mixed with PLA in various weight ratios using twin-screw extruder, resulting in PLA/SOMA-g-STARCH. Finally, the obtained PLA/SOMA-g-STARCH composites were prepared by a compression molding machines. The compatibility, thermal properties, morphology properties, and mechanical properties were characterized and evaluated. The results showed that the compatibility, surface appearance, and mechanical properties at 90 : 10 and 80 : 20 ratios of PLA/SOMA-g-STARCH were the best. PMID:24307883

  17. Poly(lactic acid)/TiO₂ nanocomposites as alternative biocidal and antifungal materials.

    PubMed

    Fonseca, Carmen; Ochoa, Almudena; Ulloa, Maria Teresa; Alvarez, Eduardo; Canales, Daniel; Zapata, Paula A

    2015-12-01

    Poly(lactic acid) (PLA) composites with titanium oxide (TiO2) ~10-nm nanoparticles were produced by the melting process and their main properties were evaluated. The nanoparticles are homogeneously dispersed in the matrix with a low degree of agglomeration, as seen by transmission electron microscopy (TEM). The crystallinity temperature increased ~12% when 5 wt.% of TiO2 was added, showing that the nanoparticles acted as nucleating agents this trend was confirmed by optical images. The elastic modulus increased ~54% compared to neat PLA at 5 wt.% of nanoparticles. Despite these improvements, PLA/TiO2 nanocomposites showed lower shear viscosity than neat PLA, possibly reflecting degradation of the polymer due to the particles. Regarding biocidal properties, after 2h of contact the PLA/TiO2 composites with 8 wt.% TiO2 showed a reduction of Escherichia coli colonies of ~82% under no UVA irradiation compared to pure PLA. This biocidal characteristic can be increased under UVA irradiation, with nanocomposites containing 8 wt.% TiO2 killing 94% of the bacteria. The PLA/TiO2 nanocomposites with 8 wt.% were also 99.99% effective against Aspergillus fumigatus under the UVA irradiation.

  18. Functionalisation and surface modification of electrospun polylactic acid scaffold for tissue engineering.

    PubMed

    Hoveizi, Elham; Nabiuni, Mohammad; Parivar, Kazem; Rajabi-Zeleti, Sareh; Tavakol, Shima

    2014-01-01

    Repair or replacement of damaged tissues using tissue engineering technology is considered to be a fine solution for enhanced treatment of different diseases such as skin diseases. Although the nanofibers made of synthetic degradable polymers, such as polylactic acid (PLA), have been widely used in the medical field, they do not favour cellular adhesion and proliferation. To enhance cell adherence on scaffold and improve biocompatibility, the surface of PLA scaffold was modified by gelatin in our experiments. For electrospinning, PLA and gelatin were dissolved in hexafluoroisopropanol (HFIP) solvent at varying compositions (PLA:gelatin at 3:7 and 7:3). The properties of the blending nanofiber scaffold were investigated by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Modified PLA/gelatin 7/3 scaffold is more suitable for fibroblasts attachment and viability than the PLA or gelatin nanofiber alone. Thus fibroblast cultured on PLA/gelatin scaffold could be an alternative way to improve skin wound healing.

  19. Manipulating dispersion and distribution of graphene in PLA through novel interface engineering for improved conductive properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aimed to enhance the conductive properties of PLA nanocomposite by controlling the dispersion and distribution of graphene within the minor phase of the polymer blend. Functionalized graphene (f-GO) was achieved by reacting graphene oxide (GO) with various silanes under the aid of an ioni...

  20. Manipulating dispersion and distribution of graphene in PLA through Novel Interface Engineering for improved conductive properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aimed to enhance the conductive properties of PLA nanocomposite by controlling the dispersion and distribution of graphene within the minor phase of the polymer blend. Functionalized graphene (f-GO) was achieved by reacting graphene oxide (GO) with various silanes under the aid of an ioni...

  1. Effects of nanoscale aggregation on mechanical properties and local dynamics of precise acid- and ion-containing polymers

    NASA Astrophysics Data System (ADS)

    Middleton, Luri Robert

    Acid- and ion-containing polymers have interchain interactions that alter polymer behavior at the nano, micro, and bulk length scales. Strong secondary-bonds act as thermo-reversible physical crosslinks between chains which drive self-assembly. Tuning theses interactions can modify bulk polymer properties including stiffness, toughness, melt viscosity, resilience, clarity, abrasion resistance and puncture resistance. Furthermore, understanding and improving the relevant factors that control transport properties would have vast implications on developing solid polymer electrolytes (SPEs) for technologically important applications including water desalination, ion exchange membranes and microelectronics. This thesis explores the structure - processing - morphology - property relationships of acid and ionic functionalized polymers. Improvements in synthetic techniques and advancements in characterization methods have enabled new studies of associating polymer systems. Synthesis of entangled, high molecular weight, linear polyethylene (PE) chains functionalized with interacting pendant groups (acidic or ionic) placed periodically along the polymer backbone represent a new class of associating polymers. These polymers with periodic distributions of acid groups are much more homogenous than the commercially available polymers. Previous studies of these polymers with greater structural homogeneity revealed great variety in morphologies of the nano-aggregated polar groups within the non-polar polymer matrix. This thesis correlated the morphologies with bulk properties through real-time X-ray scattering and tensile deformation at a range of temperatures and sample compositions. New, transient morphologies and hierarchical morphologies were observed which coincided with unusual tensile strain hardening. These results indicate that improvements in synthetic control of polymers can enhance physical properties such as tensile strain-hardening, through cooperative bonding

  2. Application of Hydrogen Bond Acidic Polycarbosilane Polymers and Solid-Phase Microextraction for the Collection of Nerve Agent Simulant

    DTIC Science & Technology

    2006-01-01

    and analyzed on a GC/MS with a SPME injection port. 20 3. Methodolgy This chapter describes the methods used to answer the research questions...can be improved by using a SPME polymer coating that is selective for nerve agents in place of current commercial polymers. This research focuses on...three hydrogen bond acidic polymers developed by the Naval Research Laboratory that have an increased affinity for nerve agents. These polymers

  3. Decreased solubilization of Pu(IV) polymers by humic acids under anoxic conditions

    NASA Astrophysics Data System (ADS)

    Xie, Jinchuan; Lin, Jianfeng; Liang, Wei; Li, Mei; Zhou, Xiaohua

    2016-11-01

    Pu(IV) polymer has a very low solubility (log[Pu(IV)aq]total = -10.4 at pH 7.2 and I = 0). However, some aspects of their environmental fate remain unclear. Humic acids are able to complex with Pu4+ ions and their dissolved species (<10 kD) in the groundwater (neutral to alkaline pH) may cause solubilization of the polymers. Also, humic acids have the native reducing capacity and potentially reduce the polymeric Pu(IV) to Pu(III)aq (log[Pu(III)aq]total = -5.3 at pH 7.2 and I = 0). Solubilization and reduction of the polymers can enhance their mobility in subsurface environments. Nevertheless, humic acids readily coat the surfaces of metal oxides via electrostatic interaction and ligand exchange mechanisms. The humic coatings are expected to prevent both solubilization and reduction of the polymers. Experiments were conducted under anoxic and slightly alkaline (pH 7.2) conditions in order to study whether humic acids have effects on stability of the polymers. The results show that the polymeric Pu(IV) was almost completely transformed into aqueous Pu(IV) in the presence of EDTA ligands. In contrast, the dissolved humic acids did not solubilize the polymers but in fact decreased their solubility by one order of magnitude. The humic coatings were responsible for the decreased solubilization. Such coatings limited the contact between the polymers and EDTA ligands, especially at the relatively high concentrations of humic acids (>0.57 mg/L). Solubilization of the humic-coated polymers was thus inhibited to a significant extent although EDTA, having the great complexation ability, was present in the humic solutions. Reduction of Pu(IV) polymers by the humic acids was also not observed in the absence of EDTA. In the presence of EDTA, the polymers were partially reduced to Pu(III)aq by the humic acids of 0.57 mg/L and the percentage of Pu(III)aq accounted for 51.7% of the total aqueous Pu. This demonstrates that the humic acids were able to reduce the aqueous Pu

  4. Enhancing charge storage of conjugated polymer electrodes with phenolic acids

    NASA Astrophysics Data System (ADS)

    Wagner, Michal; Rębiś, Tomasz; Inganäs, Olle

    2016-01-01

    We here present studies of electrochemical doping of poly(1-aminoanthraquinone) (PAAQ) films with three structurally different phenolic acids. The examined phenolic acids (sinapic, ferulic and syringic acid) were selected due to their resemblance to redox active groups, which can be found in lignin. The outstanding electrochemical stability of PAAQ films synthesized for this work enabled extensive cycling of phenolic acid-doped PAAQ films. Potentiodynamic and charge-discharge studies revealed that phenolic acid-doped PAAQ films exhibited enhanced capacitance in comparison to undoped PAAQ films, together with appearance of redox activity characteristics specific for each dopant. Electrochemical kinetic studies performed on microelectrodes affirmed the fast electron transfer for hydroquinone-to-quinone reactions with these phenolic compounds. These results imply the potential application of phenolic acids in cheap and degradable energy storage devices.

  5. Active targeting behaviors of biotinylated pluronic/poly(lactic acid) nanoparticles in vitro through three-step biotin-avidin interaction.

    PubMed

    Xiong, Xiang Yuan; Gong, Yan Chun; Li, Zi Ling; Li, Yu Ping; Guo, Liang

    2011-01-01

    In order to prepare targeted drug carriers, previously a biotin group has been attached by our group to the end of Pluronic F87/poly(lactic acid) and Pluronic P85/poly(lactic acid) block co-polymers to obtain B-F87-PLA and B-P85-PLA, respectively. In this paper, the active targeting properties of B-F87-PLA and B-P85-PLA nanoparticles in vitro were investigated through a three-step biotin-avidin interaction by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) tests and fluorescence microscopy (FM). Two kinds of human ovarian cancer cells (OVCAR-3 and SKOV-3) and paclitaxel were chosen for the cytotoxicity tests. CA-125 antigen is over-expressed on OVCAR-3 cells but not on SKOV-3 cells. The loading and release behavior of paclitaxel loaded in B-Pluronic-PLA nanoparticles were also studied. Paclitaxel loaded in both B-F87-PLA and B-P85-PLA nanoparticles shows an initial rapid release followed by a slow release period. Compared with SKOV-3 cells, the cytotoxicity results implied that paclitaxel-loaded B-Pluronic-PLA nanoparticles were delivered more effectively to OVCAR-3 cells due to the specific interaction between the biotin groups on the surface of B-Pluronic-PLA nanoparticles and the avidin/biotinylated MAb X306/CA-125 antigen complexes on the surface of OVCAR-3 cells. The active targeting properties of B-F87-PLA nanoparticles were further confirmed by FM.

  6. Different geometrical arrangements in carboxylate coordination polymers of flexible dicarboxylic acid

    SciTech Connect

    Deka, Himangshu; Sarma, Rupam; Kumari, Satchi; Khare, Alika; Baruah, Jubaraj B.

    2011-07-15

    Dicarboxylate coordination polymers (1-5) of Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II), respectively, derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid (L{sub 1}H{sub 2}) are synthesized and characterized. Depending on the coordination sites around the metal centers and coordination mode of the ligand, dimensionality of these polymers varies. The dicarboxylates adopt three spatial orientations: in-plane linear coordination, out-of-plane cis coordination and out-of-plane trans coordination mode. Both the cis and trans out-of-plane coordination modes are found to exist only if the ancillary ligand pyridine is coordinated to the metal ion. When the aquoligand coordinates the in-plane linear coordination mode of L{sub 1} predominates. The coordination polymers 4 and 5 show photoluminescence in solution. The dicarboxylate of (5-carboxymethoxy-naphthalen-1-yloxy)-acetic acid (L{sub 2}H{sub 2}) does not form coordination polymer under ambient conditions, but prefers to remain as uncoordinated anion providing hydrophobic confinement to hexa-aquometal(II) cation. Compound 3 crystallizes in P2{sub 1} space group and it shows broadband ultra-violet fluorescence centered at 352.9 nm on focusing 632.8 nm He:Ne laser. - Graphical abstract: Different geometrical arrangements in coordination polymers derived from (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid of metal ions Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) are presented. The (5-carboxymethoxy-naphthalen-1-yloxy)-acetic acid led to hexa-aquo cadmium(II) dicarboxylate. Highlights: > Structural and spectroscopic characterizations of five dicarboxylate coordination polymers of (7-carboxymethoxy-naphthalen-2-yloxy)-acetic acid with different metal ions are presented. > Different geometrical arrangements of coordination polymers stabilized in solid state are described. > Photoluminescence properties of the polymers are shown. > NLO property of a copper coordination polymer is described.

  7. 16 years research on lactic acid production with yeast - ready for the market?

    PubMed

    Sauer, Michael; Porro, Danilo; Mattanovich, Diethard; Branduardi, Paola

    2010-01-01

    The use of plastic produced from non-renewable resources constitutes a major environmental problem of the modern society. Polylactide polymers (PLA) have recently gained enormous attention as one possible substitution of petroleum derived polymers. A prerequisite for high quality PLA production is the provision of optically pure lactic acid, which cannot be obtained by chemical synthesis in an economical way. Microbial fermentation is therefore the commercial option to obtain lactic acid as monomer for PLA production. However, one major economic hurdle for commercial lactic acid production as basis for PLA is the costly separation procedure, which is needed to recover and purify the product from the fermentation broth. Yeasts, such as Saccharomyces cerevisiae (bakers yeast) offer themselves as production organisms because they can tolerate low pH and grow on mineral media what eases the purification of the acid. However, naturally yeasts do not produce lactic acid. By metabolic engineering, ethanol was exchanged with lactic acid as end product of fermentation. A vast amount of effort has been invested into the development of yeasts for lactic acid production since the first paper on this topic by Dequin and Barre appeared 1994. Now yeasts are very close to industrial exploitation - here we summarize the developments in this field.

  8. Effect of peroxide and chain extender on mechanical properties and morphology of poly (butylene succinate)/poly (lactic acid) blends

    NASA Astrophysics Data System (ADS)

    Cherykhunthod, W.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    Poly (butylene succinate) (PBS) and poly (lactic acid) (PLA) are biodegradable polymers with high potential to replace commodity fossil-based polymers in a wide range of applications. However, these two polymers are immiscible in most ratios, but partially miscible when one of the two is a major phase. In this study, a one-step process in a twin-screw extruder was used to prepare the blends between poly (butylene succinate) (PBS) as a matrix and poly (lactic acid) (PLA) as a dispersed phase. To improve mechanical properties and morphology of blends, two reactive agents, peroxide (Perkadox) and multifunctional epoxide chain extender (Joncryl) were selected and compared. All samples were characterized for melt flow index (MFI), morphology, tensile, and impact properties. The results showed that the mechanical properties and morphology of PBS/PLA blends were improved when using both reactive agents. It was demonstrated that the increased mechanical properties resulted from good interfacial adhesion between PBS and finely dispersed PLA particles. The addition of 0.075 phr Perkadox to PBS/PLA (75:25 and 80:20) blends increased elongation at break by 7.2% and 38.4%, respectively compared with the blends without reactive agents. The results from gel content also revealed the graft copolymer existed at the interface when reactive agents were added. In the case of using multifunctional epoxide chain extender, the impact strength of the blends increased.

  9. Development of polylactic acid-based materials through reactive modification

    NASA Astrophysics Data System (ADS)

    Fowlks, Alison Camille

    2009-12-01

    Polylactic acid (PLA)-based systems have shown to be of great potential for the development of materials requiring biobased content, biodegradation, and sufficient properties. The efforts in this study are directed toward addressing the current research need to overcome some of the inherent drawbacks of PLA. To meet this need, reactive extrusion was employed to develop new materials based on PLA by grafting, compounding, and polymer blending. In the first part of this work, maleic anhydride (MA) was grafted onto PLA by reactive extrusion. Two structurally different peroxides were used to initiate grafting and results were reported on the basis of grafting, molecular weight, and thermal behavior. An inverse relationship between degree of grafting and molecular weight was established. It was also found that, regardless of peroxide type, there is an optimum peroxid-to-MA ratio of 0.5:2 that promotes maximum grafting, beyond which degradation reactions become predominant. Overall, it was found that the maleated copolymer (MAPLA) could be used as an interfacial modifier in PLA-based composites. Therefore, MAPLA was incorporated into PLA-talc composites in varying concentrations. The influence of the MAPLA addition on the mechanical and thermal behavior was investigated. When added in an optimum concentration, MAPLA improved the tensile strength and crystallization of the composite. Furthermore, microscopic observation confirmed the compatibilization effect of MAPLA in PLA-talc composites. Vinyltrimethoxysilane was free-radically grafted onto the backbone of PLA and subsequently moisture crosslinked. The effects of monomer, initiator, and catalyst concentration on the degree of crosslinking and the mechanical and thermal properties were investigated. The presence of a small amount of catalyst showed to be a major contributor to the crosslinking formation in the time frame investigated, shown by an increase in gel content and decrease in crystallinity. Furthermore

  10. Effect of gamma irradiation on physicochemical properties of commercial poly(lactic acid) clamshell for food packaging

    NASA Astrophysics Data System (ADS)

    Madera-Santana, Tomás J.; Meléndrez, R.; González-García, Gerardo; Quintana-Owen, Patricia; Pillai, Suresh D.

    2016-06-01

    Poly(lactic acid) (PLA) is a well-known biodegradable polymer with strong potential application in food packaging industry. In this paper, samples of PLA clamshell for tomatoes packaging were exposed with 60CO γ-ray's source (1.33 MeV) at different dose levels (0, 10, 60, 150, 300, and 600 kGy), at room temperature and in presence of air. The physicochemical properties of neat PLA and sample exposed to gamma irradiation were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and tensile measurements. Results show as the dose increases, the molecular weight (Mw), melting temperature (Tm), tensile strength and elongation at break decreased. However, the tensile modulus increased with increasing doses. The surface of PLA clamshells was degraded (scratches and minor cracks) when samples were exposed to doses greater than 60 kGy.

  11. Effects of ultraviolet light (315 nm), temperature and relative humidity on the degradation of polylactic acid plastic films.

    PubMed

    Copinet, Alain; Bertrand, Celine; Govindin, Stephanie; Coma, Veronique; Couturier, Yves

    2004-05-01

    The influence of temperature (30, 45 and 60 degrees C) and relative humidity (RH) (30%, 50% and 100%) on the degradation of poly(l-lactic acid) (PLA) films were studied. In addition, the effects of ultraviolet (UV) light (315 nm) on the degradation of PLA films were also analyzed. Various analytical techniques were applied to observe changes in the properties of PLA polymer films. FTIR spectroscopy was used as semi-quantitative method to get information about the chemistry of the degradative process. The degradation rate of PLA was enhanced by increasing temperature and RH, factors responsible for a faster reduction of the weight-average molecular weight (M(W)), of the glass transition temperature (Tg) and of the percentage of elongation at break. Moreover, UV treatment accelerated these phenomena.

  12. Degradable, pH-sensitive, membrane-destabilizing, comb-like polymers for intracellular delivery of nucleic acids.

    PubMed

    Lin, Yen-Ling; Jiang, Guohua; Birrell, Lisa K; El-Sayed, Mohamed E H

    2010-09-01

    This report describes the design and synthesis of a new series of degradable, pH-sensitive, membrane-destabilizing, comb-like polymers that can enhance the intracellular delivery of therapeutic nucleic acids. These comb-like polymers are based on a diblock polymer backbone where the first block is a copolymer of pH-sensitive ethyl acrylic acid (EAA) monomers and hydrophobic butyl methacrylate (BMA) or hexyl methacrylate monomers. The second block is a homopolymer of N-acryloxy succinimide (NASI) or ss-benzyl l-aspartate N-carboxy-anhydride (BLA-NCA) monomers, which are functionalized to allow controlled grafting of hydrophobic HMA and cationic trimethyl aminoethyl methacrylate (TMAEMA) copolymers via acid-labile hydrazone linkages. These comb-like polymers displayed high hemolytic activity in acidic solutions, which increased with the increase in polymer concentration. All comb-like polymers degraded into small fragments upon incubation in an acidic solution (pH 5.8) due to hydrolysis of the hydrazone linkages connecting the hydrophobic/cationic grafts to the polymer backbone. Comb-like polymers successfully complexed anti-GAPDH siRNA molecules into serum- and nuclease-stable particles, which successfully silenced GAPDH expression at both the mRNA and protein levels. These results collectively indicate the potential of these new comb-like polymers to serve as vehicles for effective intracellular delivery of therapeutic nucleic acids.

  13. Fe-nitrilotriacetic acid coordination polymer nanowires: an effective sensing platform for fluorescence-enhanced nucleic acid detection

    NASA Astrophysics Data System (ADS)

    Zhou, Yunchun; Liu, Qian; Sun, Xuping; Kong, Rongmei

    2017-02-01

    The determination of specific nucleic acid sequences is key in identifying disease-causing pathogens and genetic diseases. In this paper we report the utilization of Fe-nitrilotriacetic acid coordination polymer nanowires as an effective nanoquencher for fluorescence-enhanced nucleic acid detection. The detection is fast and the whole process can be completed within 15 min. This nanosensor shows a low detection limit of 0.2 nM with selectivity down to single-base mismatch. This work provides us with an attractive sensing platform for applications.

  14. Titania-based molecularly imprinted polymer for sulfonic acid dyes prepared by sol-gel method.

    PubMed

    Li, Man; Li, Rong; Tan, Jin; Jiang, Zi-Tao

    2013-03-30

    A novel titania-based molecularly imprinted polymer (MIP) was synthesized through sol-gel process with sunset yellow (Sun) as template, without use of functional monomer. MIP was used as a solid-phase extraction material for the isolation and enrichment of sulfonic acid dyes in beverages. The results showed that MIP exhibited better selectivity, higher recovery and adsorption capacity for the sulfonic acid dyes compared to the non-imprinted polymer (NIP). MIP presented highest extraction selectivity to Sun when pH less than or equal to 3. The adsorption capacity was 485.9 mg g(-1), which was larger than that of NIP (384.7 mg g(-1)). The better clean-up ability demonstrated the capability of MIP for the isolation and enrichment of sulfonic acid dyes in complicated food samples. The mean recoveries for the sulfonic acid dyes on MIP were from 81.9% to 97.2% in spiked soft drink.

  15. Preparation and application of abietic acid-derived optically active helical polymers and their chiral hydrogels.

    PubMed

    Yao, Fei; Zhang, Dongyue; Zhang, Chaohong; Yang, Wantai; Deng, Jianping

    2013-02-01

    A novel chiral monomer N-propargyl abietamide, M1, was synthesized from abietic acid and catalytically polymerized with (nbd)Rh+B-(C6H5)4 (nbd=norbornadiene), providing polymer [poly(1)] with a molecular weight of 13,000-36,000 at a yield of 59-84%. Poly(1) did not form stable helices in tetrahydrofuran at room temperature whereas copolymerization of M1 and the achiral N-propargylamide monomer, M2, led to the formation of helical optically active copolymers as indicated by circular dichroism studies, UV-vis spectroscopy, and specific optical rotation measurements. Hydrogels were prepared based on an optically active helical copolymer, poly(M1(0.32)-co-M2(0.68)) that exhibited enantioselective recognition toward l-alanine. The novel chiral polymers derived from abietic acid are expected to find applications in such areas as chiral recognition, chiral resolution, and chiral catalysis.

  16. A Biodegradable Thermoset Polymer Made by Esterification of Citric Acid and Glycerol

    PubMed Central

    Halpern, Jeffrey M.; Urbanski, Richard; Weinstock, Allison K.; Iwig, David F.; Mathers, Robert T.; von Recum, Horst

    2014-01-01

    A new biomaterial, a degradable thermoset polymer, was made from simple, economical, biocompatable monomers without the need for a catalyst. Glycerol and citric acid, non-toxic and renewable reagents, were crosslinked by a melt polymerization reaction at temperatures from 90-150°C. Consistent with a condensation reaction, water was determined to be the primary byproduct. The amount of crosslinking was controlled by the reaction conditions, including temperature, reaction time, and ratio between glycerol and citric acid. Also, the amount of crosslinking was inversely proportional to the rate of degradation. As a proof-of-principle for drug delivery applications, gentamicin, an antibiotic, was incorporated into the polymer with preliminary evaluations of antimicrobial activity. The polymers incorporating gentamicin had significantly better bacteria clearing of Staphylococcus aureus compared to non-gentamicin gels for up to nine days. PMID:23737239

  17. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  18. The Chemistry of Polymers, Proteins, and Nucleic Acids: A Short Course on Macromolecules for Secondary Schools.

    ERIC Educational Resources Information Center

    Lulav, Ilan; Samuel, David

    1985-01-01

    Describes a unit on macromolecules that has been used in the 12th grade of many Israeli secondary schools. Topic areas in the unit include synthetic polymers, biological macromolecules, and nucleic acids. A unit outline is provided in an appendix. (JN)

  19. One-dimensional alignment of strong Lewis acid sites in a porous coordination polymer.

    PubMed

    Kajiwara, Takashi; Higuchi, Masakazu; Yuasa, Akihiro; Higashimura, Hideyuki; Kitagawa, Susumu

    2013-11-18

    A new lanthanoid porous coordination polymer, La-BTTc (BTTc = benzene-1,3,5-tris(2-thiophene-5-carboxylate)), was synthesized and structurally characterized to have densely aligned one-dimensional open metal sites, which were found to act as strong Lewis acid sites after the removal of the coordinated solvent.

  20. Acid-base properties of adhesive dental polymers.

    PubMed

    Morra, M

    1993-11-01

    The surface energetics of three resins (polymethylmethacrylate, polyhydroxyethylmethacrylate, and Bis-GMA/triethyleneglycoldimethacrylate) commonly used in adhesive interactions with tooth hard tissues were evaluated according to the Fowkes acid-base theory of interfacial interactions. From the measurement of the contact angle of test acidic and basic liquids on the sample surfaces, the acid-base contribution to the work of adhesion was evaluated. Results show that polyhydroxyethylmethacrylate is a comparatively strong Lewis base, a finding that can explain the important role played by this material in the formulation of dentin adhesive.

  1. Thermoplastic starch/polyester films: effects of extrusion process and poly (lactic acid) addition.

    PubMed

    Shirai, Marianne Ayumi; Olivato, Juliana Bonametti; Garcia, Patrícia Salomão; Müller, Carmen Maria Olivera; Grossmann, Maria Victória Eiras; Yamashita, Fabio

    2013-10-01

    Biodegradable films were produced using the blown extrusion method from blends that contained cassava thermoplastic starch (TPS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) with two different extrusion processes. The choice of extrusion process did not have a significant effect on the mechanical properties, water vapor permeability (WVP) or viscoelasticity of the films, but the addition of PLA decreased the elongation, blow-up ratio (BUR) and opacity and increased the elastic modulus, tensile strength and viscoelastic parameters of the films. The films with 20% PLA exhibited a lower WVP due to the hydrophobic nature of this polymer. Morphological analyses revealed the incompatibility between the polymers used.

  2. Effect of reactive agent and transesterification catalyst on properties of PLA/PBAT blends

    NASA Astrophysics Data System (ADS)

    Pitivut, S.; Suttiruengwong, S.; Seadan, M.

    2015-07-01

    This research aimed to study the properties of poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blends with two different reactive systems: free radical reaction through peroxide (Perkadox) and transesterification catalyst (tetrabutyl titanate; TBT). Two blends composed of PLA as a matrix phase with the composition of 80 and 70 percent by weight. PLA/PBAT blends with Perkadox were prepared in twin screw extruder, whereas PLA/PBAT blends with TBT were prepared in an internal mixer. The morphology of the blends was investigated by scanning electron microscope (SEM). Tensile and impact testingsof the blends were reported. In case of the blends with Perkadox, SEM micrographs revealed that the size of particles was substantially reduced when adding more Perkadox. Young's modulus and the tensile strength of all blend ratios were insignificantly changed, whereas the elongation at break was decreased when compared to non-reactive blends due to the possible crosslinking reaction as observed from melt flow index (MFI) values. When adding Perkadox, the impact strength of PLA/PBAT (80/20) remained almost unchanged. However, the impact strength of PLA/PBAT (70/30) was enhanced, increasing to 110% for 0.05 phr Perkadox. In case of the blends with TBT, SEM micrographs showed the decrease in the particle size of PBAT phase when adding TBT. Young's modulus and the tensile strength of all blend ratios were not different, but the elongation at break was improved when adding TBT owing to the transesterification reaction. For PLA/PBAT (80/20), the elongation at break was increased by 39%, whereas the elongation at break was increased by 15% for PLA/PLA (70/30). The impact strength of all blend ratios unaffected.

  3. Release of triamcinolone acetonide from mucoadhesive polymer composed of chitosan and poly(acrylic acid) in vitro.

    PubMed

    Ahn, Jae-Soon; Choi, Hoo-Kyun; Chun, Myong-Kwan; Ryu, Jei-Man; Jung, Jae-Hee; Kim, Yue-Un; Cho, Chong-Su

    2002-03-01

    Transmucosal drug delivery (TMD) system using mucoadhesive polymer has been recently interested due to the rapid onset of action, high blood level, avoidance of the first-pass effect and the exposure of the drug to the gastrointestinal tract. A novel mucoadhesive polymer complex composed of chitosan and poly(acrylic acid) (PAA) was prepared by template polymerization of acrylic acid in the presence of chitosan for the TMD system. Triamcinolone acetonide (TAA) was loaded into the chitosan/PAA polymer complex film. TAA was evenly dispersed in chitosan, PAA polymer complex film without interaction with polymer complex. Release behavior of TAA from the mucoadhesive polymer film was dependent on time, pH, loading content of drug, and chitosan PAA ratio. The analysis of the drug release from the mucoadhesive film showed that TAA might be released from the chitosan/PAA polymer complex film through non-Fickian diffusion mechanism.

  4. Is 3D printing safe? Analysis of the thermal treatment of thermoplastics: ABS, PLA, PET, and nylon.

    PubMed

    Wojtyła, Szymon; Klama, Piotr; Baran, Tomasz

    2017-02-06

    The fast development of low-cost desktop three-dimensional (3D) printers has made those devices widely accessible for goods manufacturing at home. However, is it safe? Users may belittle the effects or influences of pollutants (organic compounds and ultrafine particles) generated by the devices in question. Within the scope of this study, the authors attempt to investigate thermal decomposition of the following commonly used, commercially available thermoplastic filaments: acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), polyethylene terephthalate (PET), and nylon. Thermogravimetric analysis has shown the detailed thermal patterns of their behavior upon increasing temperature in neutral atmosphere, while GC analysis of organic vapors emitted during the process of heating thermoplastics have made it possible to obtain crucial pieces of information about the toxicity of 3D printing process. The conducted study has shown that ABS is significantly more toxic than PLA. The emission of volatile organic compounds (VOC) has been in the range of 0.50 μmol/h. Styrene has accounted for more than 30% of total VOC emitted from ABS, while for PLA, methyl methacrylate has been detected as the predominant compound (44% of total VOCs emission). Moreover, the authors have summarized available or applicable methods that can eliminate formed pollutants and protect the users of 3D printers. This paper summarizes theoretical knowledge on thermal degradation of polymers used for 3D printers and shows results of authors' investigation, as well as presents forward-looking solutions that may increase the safety of utilization of 3D printers.

  5. iPLA2• Knockout Mouse, a Genetic Model for Progressive Human Motor Disorders, Develops Age-Related Neuropathology

    PubMed Central

    Blanchard, Helene; Taha, Ameer Y.; Cheon, Yewon; Kim, Hyung-Wook; Turk, John; Rapoport, Stanley I.

    2015-01-01

    Calcium-independent phospholipase A2 group VIa (iPLA2β) preferentially releases docosahexaenoic acid (DHA) from the sn-2 position of phospholipids. Mutations of its gene, PLA2G6, are found in patients with several progressive motor disorders, including Parkinson disease. At 4 months, PLA2G6 knockout mice (iPLA2β−/−) show minimal neuropathology but altered brain DHA metabolism. By 1 year, they develop motor disturbances, cerebellar neuronal loss, and striatal α-synuclein accumulation. We hypothesized that older iPLA2β−/− mice also would exhibit inflammatory and other neuropathological changes. Real-time polymerase chain reaction and Western blotting were performed on whole brain homogenate from 15 to 20-month old male iPLA2β−/− or wild-type (WT) mice. These older iPLA2β−/− mice compared with WT showed molecular evidence of microglial (CD-11b, iNOS) and astrocytic (glial fibrillary acidic protein) activation, disturbed expression of enzymes involved in arachidonic acid metabolism, loss of neuroprotective brain derived neurotrophic factor, and accumulation of cytokine TNF-α messenger ribonucleic acid, consistent with neuroinflammatory pathology. There was no evidence of synaptic loss, of reduced expression of dopamine active reuptake transporter, or of accumulation of the Parkinson disease markers Parkin or Pink1. iPLA2γ expression was unchanged. iPLA2β deficient mice show evidence of neuroinflammation and associated neuropathology with motor dysfunction in later life. These pathological biomarkers could be used to assess efficacy of dietary intervention, antioxidants or other therapies on disease progression in this mouse model of progressive human motor diseases associated with a PLA2G6 mutation. PMID:24919816

  6. Molecularly imprinted polymer microspheres for solid-phase extraction of protocatechuic acid in Rhizoma homalomenae.

    PubMed

    Chen, Fang-Fang; Wang, Guo-Ying; Shi, Yan-Ping

    2011-10-01

    Molecularly imprinted polymers (MIPs) had been prepared by precipitation polymerization method using acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, acetonitrile as the porogen solvent and protocatechuic acid (PA), one of phenolic acids, as the template molecule. The MIPs were characterized by scanning electron microscopy and Fourier transform infrared, and their performance relative to non-imprinted polymers was assessed by equilibrium binding experiments. Six structurally similar phenolic acids, including p-hydroxybenzoic acid, gallic acid, salicylic acid, syringic acid, vanillic acid, ferulic acid were selected to assess the selectivity and recognition capability of the MIPs. The MIPs were applied to extract PA from the traditional Chinese medicines as a solid-phase extraction sorbent. The resultant cartridge showed that the MIPs have a good extraction performance and were able to selectively extract almost 82% of PA from the extract of Rhizoma homalomenae. Thus, the proposed molecularly imprinted-solid phase extraction-high performance liquid chromatography method can be successfully used to extract and analyse PA in traditional Chinese medicines.

  7. Retinal pigment epithelial cell adhesion on novel micropatterned surfaces fabricated from synthetic biodegradable polymers.

    PubMed

    Lu, L; Nyalakonda, K; Kam, L; Bizios, R; Göpferich, A; Mikos, A G

    2001-02-01

    Novel synthetic biodegradable polymer substrates with specific chemical micropatterns were fabricated from poly(DL-lactic-coglycolic acid) (PLGA) and diblock copolymers of poly(ethylene glycol) and poly(DL-lactic acid) (PEG/PLA). Thin films of PLGA and PEG/PLA supported and inhibited, respectively, retinal pigment epithelial (RPE) cell proliferation, with a corresponding cell density of 352,900 and 850 cells/cm2 after 7 days (from an initial seeding density of 15,000 cells/cm2). A microcontact printing technique was used to define arrays of circular (diameter of 50 microm) PLGA domains surrounded and separated by regions (width of 50 microm) of PEG/PLA. Reversed patterns composed of PEG/PLA circular domains surrounded by PLGA regions were also fabricated. Both micropatterned surfaces were shown to affect initial RPE cell attachment, limit cell spreading, and promote the characteristic cuboidal cell morphology during the 8-h period of the experiments. In contrast, RPE cells on plain PLGA (control films) were elongated and appeared fibroblast-like. The reversed patterns had continuous PLGA regions that allowed cell-cell interactions and thus higher cell adhesion. These results demonstrate the feasibility of fabricating micropatterned synthetic biodegradable polymer surfaces to control RPE cell morphology.

  8. Swellable, water- and acid-tolerant polymer sponges for chemoselective carbon dioxide capture.

    PubMed

    Woodward, Robert T; Stevens, Lee A; Dawson, Robert; Vijayaraghavan, Meera; Hasell, Tom; Silverwood, Ian P; Ewing, Andrew V; Ratvijitvech, Thanchanok; Exley, Jason D; Chong, Samantha Y; Blanc, Frédéric; Adams, Dave J; Kazarian, Sergei G; Snape, Colin E; Drage, Trevor C; Cooper, Andrew I

    2014-06-25

    To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO2 specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO2 capacity and high CO2 selectivity under conditions relevant to precombustion CO2 capture. Unlike polar adsorbents, such as zeolite 13x and the metal-organic framework, HKUST-1, the CO2 adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO2 in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO2 capacities and much better CO2 selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture.

  9. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid

    NASA Astrophysics Data System (ADS)

    Zhan, Honglei; Liang, Jun F.

    2016-12-01

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC50 < 5.0 μg/mL) to cancer cells compared to synthetic polymer coated CPT nanocrystals and free CPT. Surface coating using non-covalent polymers from self-assembled boric acid will have wide biomedical applications especially in biomaterials and drug delivery field.

  10. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid.

    PubMed

    Zhan, Honglei; Liang, Jun F

    2016-12-09

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC50 < 5.0 μg/mL) to cancer cells compared to synthetic polymer coated CPT nanocrystals and free CPT. Surface coating using non-covalent polymers from self-assembled boric acid will have wide biomedical applications especially in biomaterials and drug delivery field.

  11. Extreme Activity of Drug Nanocrystals Coated with A Layer of Non-Covalent Polymers from Self-Assembled Boric Acid

    PubMed Central

    Zhan, Honglei; Liang, Jun F.

    2016-01-01

    Non-covalent polymers have remarkable advantages over synthetic polymers for wide biomedical applications. In this study, non-covalent polymers from self-assembled boric acid were used as the capping reagent to replace synthetic polymers in drug crystallization. Under acidic pH, boric acid self-assembled on the surface of drug nanocrystals to form polymers with network-like structures held together by hydrogen bonds. Coating driven by boric acid self-assembly had negligible effects on drug crystallinity and structure but resulted in drug nanocrystals with excellent dispersion properties that aided in the formation of a more stable suspension. Boric acid coating improved drug stability dramatically by preventing drug molecules from undergoing water hydrolysis in a neutral environment. More importantly, the specific reactivity of orthoboric groups to diols in cell glycocalyx facilitated a rapid cross-membrane translocation of drug nanocrystals, leading to efficient intracellular drug delivery, especially on cancer cells with highly expressed sialic acids. Boric acid coated nanocrystals of camptothecin, an anticancer drug with poor aqueous solubility and stability, demonstrated extreme cytotoxic activity (IC50 < 5.0 μg/mL) to cancer cells compared to synthetic polymer coated CPT nanocrystals and free CPT. Surface coating using non-covalent polymers from self-assembled boric acid will have wide biomedical applications especially in biomaterials and drug delivery field. PMID:27934922

  12. Low-Cost Nanocellulose-Reinforced High-Temperature Polymer Composites for Additive Manufacturing

    SciTech Connect

    Ozcan, Soydan; Tekinalp, Halil L.; Love, Lonnie J.; Kunc, Vlastimil; Nelson, Kim

    2016-07-13

    ORNL worked with American Process Inc. to demonstrate the potential use of bio-based BioPlus® lignin-coated cellulose nanofibrils (L-CNF) as a reinforcing agent in the development of polymer feedstock suitable for additive manufacturing. L-CNF-reinforced polylactic acid (PLA) testing coupons were prepared and up to 69% increase in tensile strength and 133% increase in elastic modulus were demonstrated.

  13. 40 CFR 721.2076 - D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false D-Glucuronic acid, polymer with 6...-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium... identified as D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium...

  14. 40 CFR 721.10369 - Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Carbonic acid, diphenyl ester, polymer... Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1-methylethylidene) bis... identified as carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and...

  15. 40 CFR 721.2076 - D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false D-Glucuronic acid, polymer with 6...-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium... identified as D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium...

  16. Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

    NASA Astrophysics Data System (ADS)

    Nazarenko, O. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder.

  17. Biodegradation of lactic acid based polymers under controlled composting conditions and evaluation of the ecotoxicological impact.

    PubMed

    Tuominen, Jukka; Kylmä, Janne; Kapanen, Anu; Venelampi, Olli; Itävaara, Merja; Seppälä, Jukka

    2002-01-01

    The biodegradability of lactic acid based polymers was studied under controlled composting conditions (CEN prEN 14046), and the quality of the compost was evaluated. Poly(lactic acids), poly(ester-urethanes), and poly(ester-amide) were synthesized and the effects of different structure units were investigated. The ecotoxicological impact of compost samples was evaluated by biotests, i.e., by the Flash test, measuring the inhibition of light production of Vibrio fischeri, and by plant growth tests with cress, radish, and barley. All the polymers biodegraded to over 90% of the positive control in 6 months, which is the limit set by the CEN standard. Toxicity was detected in poly(ester-urethane) samples where chain linking of lactic acid oligomers had been carried out with 1,6-hexamethylene diisocyanate (HMDI). Both the Flash test and the plant growth tests indicated equal response to initial HMDI concentration in the polymer. All other polymers, including poly(ester-urethane) chain linked with 1,4-butane diisocyanate, showed no toxicological effect.

  18. [Degradable performance and bio-mineralization function of PLA-PEG-PLA/PLA tissue engineering scaffold in vitro and in vivo].

    PubMed

    Ge, Jianhua; Wang, Yingjun; Min, Shaoxiong

    2010-10-01

    The degradable performance and bio-mineralization function of PLA-PEG-PLA/PLA tissue engineering scaffolds in vitro and in vivo were systematically studied. The X-ray diffraction and Fourier transform infrared spectra showed that there was the deposition of bone-like carbonate hydroxyapatite on the surface of scaffolds. We found that the weight of scaffolds did not always decrease with the prolongation of time in vitro. At the same time, we found that after the PLA-PEG-PLA/PLA tissue engineering scaffolds were embedded in skulls of rhesus monkeys, the new bone area reached 75% at the 12th week. Histological observation showed that the new bones were rebuilt and knitted bones were formed at the 12th week. These findings meant that the PLA-PEG-PLA/PLA tissue engineering scaffolds were potential in clinical use.

  19. Electrospun polymer nanofibers reinforced by tannic acid/Fe+++ complexes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nanofibers and fibrous mats of polyvinyl alcohol (PVA) loaded with tannic acid (TA) and ferric ion (Fe+++) complexes (TA-Fe+++) were synthesized by the electrospinning technique. The spinning solutions were characterized for surface tension, electrical conductivity, and viscosity. It was found that ...

  20. Amplified spontaneous emission from the exciplex state of a conjugated polymer "PFO" in oleic acid

    NASA Astrophysics Data System (ADS)

    Idriss, Hajo; Taha, Kamal K.; Aldaghri, O.; Alhathlool, R.; AlSalhi, M. S.; Ibnaouf, K. H.

    2016-09-01

    The amplified spontaneous emission (ASE) characteristics of a conjugated polymer poly (9, 9-dioctylfluorenyl-2, 7-diyl) (PFO) in oleic acid have been studied under different concentrations and temperatures. Here, the ASE spectra of PFO in oleic acid have been obtained using a transverse cavity configuration where the conjugated PFO was pumped by laser pulses from the third harmonic of Nd: YAG laser (355 nm). The PFO in oleic acid produces ASE from an exciplex state - a new molecular species. The obtained results were compared with the PFO in benzene. Such ASE spectra from the exciplex state have not been observed for the PFO in benzene.

  1. Fabrication of novel high performance ductile poly(lactic acid) nanofiber scaffold coated with poly(vinyl alcohol) for tissue engineering applications.

    PubMed

    Abdal-Hay, Abdalla; Hussein, Kamal Hany; Casettari, Luca; Khalil, Khalil Abdelrazek; Hamdy, Abdel Salam

    2016-03-01

    Poly(lactic acid) (PLA) nanofiber scaffold has received increasing interest as a promising material for potential application in the field of regenerative medicine. However, the low hydrophilicity and poor ductility restrict its practical application. Integration of hydrophilic elastic polymer onto the surface of the nanofiber scaffold may help to overcome the drawbacks of PLA material. Herein, we successfully optimized the parameters for in situ deposition of poly(vinyl alcohol), (PVA) onto post-electrospun PLA nanofibers using a simple hydrothermal approach. Our results showed that the average fiber diameter of coated nanofiber mat is about 1265±222 nm, which is remarkably higher than its pristine counterpart (650±180 nm). The hydrophilicity of PLA nanofiber scaffold coated with a PVA thin layer improved dramatically (36.11±1.5°) compared to that of pristine PLA (119.7±1.5°) scaffold. The mechanical testing showed that the PLA nanofiber scaffold could be converted from rigid to ductile with enhanced tensile strength, due to maximizing the hydrogen bond interaction during the heat treatment and in the presence of PVA. Cytocompatibility performance of the pristine and coated PLA fibers with PVA was observed through an in vitro experiment based on cell attachment and the MTT assay by EA.hy926 human endothelial cells. The cytocompatibility results showed that human cells induced more favorable attachment and proliferation behavior on hydrophilic PLA composite scaffold than that of pristine PLA. Hence, PVA coating resulted in an increase in initial human cell attachment and proliferation. We believe that the novel PVA-coated PLA nanofiber scaffold developed in this study, could be a promising high performance biomaterial in regeneration medicine.

  2. Assessing Technology Innovation in the PLA

    DTIC Science & Technology

    2015-03-01

    TECHNOLOGY INNOVATION IN THE PLA by Gary L. Pembleton March 2015 Thesis Co-Advisors: Wade Huntley Michael Glosny THIS PAGE INTENTIONALLY LEFT...SUBTITLE 5. FUNDING NUMBERS ASSESSING TECHNOLOGY INNOVATION IN THE PLA 6. AUTHOR(S) Gaty L. Pembleton 7. PERFORMING ORGANIZATION NA:iVIE(S) AND ADDRESS(ES...standard for identifying innovation, and applies this standard to the PLAN and PLAAF. Historically, technological innovat ion is either overlooked or

  3. Enhancing Cation Diffusion and Suppressing Anion Diffusion via Lewis-Acidic Polymer Electrolytes.

    PubMed

    Savoie, Brett M; Webb, Michael A; Miller, Thomas F

    2017-02-02

    Solid polymer electrolytes (SPEs) have the potential to increase both the energy density and stability of lithium-based batteries, but low Li(+) conductivity remains a barrier to technological viability. SPEs are designed to maximize Li(+) diffusivity relative to the anion while maintaining sufficient salt solubility. It is thus remarkable that poly(ethylene oxide) (PEO), the most widely used SPE, exhibits Li(+) diffusivity that is an order of magnitude smaller than that of typical counterions at moderate salt concentrations. We show that Lewis-basic polymers like PEO favor slow cation and rapid anion diffusion, while this relationship can be reversed in Lewis-acidic polymers. Using molecular dynamics, polyboranes are identified that achieve up to 10-fold increases in Li(+) diffusivities and significant decreases in anion diffusivities, relative to PEO in the dilute-ion regime. These results illustrate a general principle for increasing Li(+) diffusivity and transference number with chemistries that exhibit weaker cation and stronger anion coordination.

  4. Citric Acid Capped Iron Oxide Nanoparticles as an Effective MALDI Matrix for Polymers

    NASA Astrophysics Data System (ADS)

    Liang, Qiaoli; Sherwood, Jennifer; Macher, Thomas; Wilson, Joseph M.; Bao, Yuping; Cassady, Carolyn J.

    2017-03-01

    A new matrix-assisted laser desorption ionization (MALDI) mass spectrometry matrix is proposed for molecular mass determination of polymers. This matrix contains an iron oxide nanoparticle (NP) core with citric acid (CA) molecules covalently bound to the surface. With the assistance of additives, the particulate nature of NPs allows the matrix to mix uniformly with polar or nonpolar polymer layers and promotes ionization, which may simplify matrix selection and sample preparation procedures. Several distinctively different polymer classes (polyethyleneglycol (PEG), polywax/polyethylene, perfluoropolyether, and polydimethylsiloxane) are effectively detected by the water or methanol dispersed NPCA matrix with NaCl, NaOH, LiOH, or AgNO3 as additives. Furtheremore, successful quantitative measurements of PEG1000 using polypropylene glycol 1000 as an internal standard are demonstrated.

  5. Citric Acid Capped Iron Oxide Nanoparticles as an Effective MALDI Matrix for Polymers

    NASA Astrophysics Data System (ADS)

    Liang, Qiaoli; Sherwood, Jennifer; Macher, Thomas; Wilson, Joseph M.; Bao, Yuping; Cassady, Carolyn J.

    2016-12-01

    A new matrix-assisted laser desorption ionization (MALDI) mass spectrometry matrix is proposed for molecular mass determination of polymers. This matrix contains an iron oxide nanoparticle (NP) core with citric acid (CA) molecules covalently bound to the surface. With the assistance of additives, the particulate nature of NPs allows the matrix to mix uniformly with polar or nonpolar polymer layers and promotes ionization, which may simplify matrix selection and sample preparation procedures. Several distinctively different polymer classes (polyethyleneglycol (PEG), polywax/polyethylene, perfluoropolyether, and polydimethylsiloxane) are effectively detected by the water or methanol dispersed NPCA matrix with NaCl, NaOH, LiOH, or AgNO3 as additives. Furtheremore, successful quantitative measurements of PEG1000 using polypropylene glycol 1000 as an internal standard are demonstrated.

  6. Properties of the acrylic acid polymers obtained by atmospheric pressure plasma polymerization

    NASA Astrophysics Data System (ADS)

    Topala, Ionut; Dumitrascu, Nicoleta; Popa, Gheorghe

    2009-01-01

    Plasma polymers of acrylic acid were obtained using an atmospheric pressure discharge system. The plasma polymerization reactor uses a dielectric barrier discharge, with the polyethylene terephthalate dielectric acting as substrate for deposition. The plasma was characterized by specific electrical measurements, monitoring the applied voltage and the discharge current. Based on the spatially resolved optical emission spectroscopy, we analyzed the distribution of the excited species in the discharge gap, specific plasma temperatures (vibrational and gas temperatures) being calculated with the Boltzmann plot method. The properties of the plasma polymer films were investigated by contact angle measurements, infrared and UV-Vis spectroscopy, scanning electron microscopy. The films produced by plasma polymerization at atmospheric pressure showed a hydrophilic character, in correlation with the strong absorbance of OH groups in the FTIR spectrum. Moreover, the surface of the plasma polymers at micrometric scale is smooth and free of defects without particular features.

  7. Preparation of porous PLA/DBM composite biomaterials and experimental research of repair rabbit radius segmental bone defect.

    PubMed

    Zhang, Yumin; Wang, Jianru; Wang, Jue; Niu, Xiaojun; Liu, Jianchun; Gao, Lan; Zhai, Xiaoyan; Chu, Kaibo

    2015-12-01

    Bone substitutes are used in wide range of orthopaedic application. An ideal bone substitute should exhibit superior osteoinductive and osteoconductive properties. Neither bio-derived materials nor synthetic materials can meet the needs of an ideal bone substitute. Preparation of composite materials is a promising way to improve properties of biomaterial. In this study, the porous poly lactic acid (PLA)/demineralized bone matrix (DBM) composite biomaterials prepared by supercritical CO2 technique were implanted to repair rabbit radius segmental bone defect. By comparing with PLA and bone autograft, the X-ray result and histological analysis showed the repair effect of PLA/DBM porous composite materials is significantly better than that of the PLA group and the blank control group, and is similar to autologous bone. The PLA/DBM can promote the healing of bone defects and can be used as a kind of ideal alternative materials to repair bone defects.

  8. Polymorphisms in PLA2G6 and PLA2G4C genes for calcium-independent phospholipase A2 do not contribute to attenuated niacin skin flush response in schizophrenia patients.

    PubMed

    Nadalin, S; Radović, I; Buretić-Tomljanović, A

    2015-09-01

    We hypothesized that attenuated niacin skin flushing in schizophrenia patients might be associated with polymorphic variants in PLA2G6 and PLA2G4C genes (rs4375 and rs1549637 variations) which encode calcium-independent phospholipase A2 beta (iPLA2β) and cytosolic phospholipase A2 gamma (cPLA2γ) enzymes. The iPLA2β and cPLA2γ may play an important role in niacin-mediated signaling; in addition to their major role - mediating phospholipids remodeling, which alters membrane receptors and signal transduction, they regulate the reservoir of arachidonic acid for prostaglandins synthesis. Skin response to topical niacin of 0.1M, 0.01M, 0.001M and 0.0001M concentrations in 75 schizophrenia patients was rated using the method of volumetric niacin response (VNR). Neither PLA2G6 nor PLA2G4C gene polymorphisms were significantly associated with VNR values. Furthermore, polymorphisms׳ synergy on niacin skin flushing was also not detected.

  9. Synthesis and characterization of phosphonate ester and phosphonic acid containing polymers and blends

    NASA Astrophysics Data System (ADS)

    Tamber, Harinder Singh

    1997-12-01

    Vinylbenzylphosphonate ester (VBP) was homopolymerized and copolymerized with methyl methacrylate and the reactivity ratio of this pair of monomers was calculated from Finneman-Ross and Kelen-Tudos methods. These methods provided identical values, which are rsb1 (VBP) = 1.23 and rsb2(MMA) = 0.43. The phosphonate ester group, -P = O(OEt)sb2; in VBP and poly(VBP-MMA) copolymers was hydrolysed to phosphonic acid, -P = O(OH)sb2; at room temperature to obtain vinylbenzylphosphonic acid (VBPa) and poly(VBPa-MMA) copolymers. sp1H, sp{13}C & sp{31}P NMR spectroscopy, DSC and FTIR were used to monitor the hydrolysis of these phosphorylated monomers and polymers. The glass transition temperature of PVBP was 13sp°C as compared to 198sp°C of PVBPa. The phosphoryl group in the parent polymers acts as a self plasticizing agent resulting in lower glass transition temperature, on the other hand inter and intra hydrogen bonding results in broad and high Tsbg in these hydrolysed polymers. VBP was also polymerized with BisGMA or TEGDM to low conversions. These oligomers were tested in vitro as potential adhesive materials for dental/enamel and composite resins. The phosphonate esters containing polymers show substantial capacity to dissolve the heavy metal salts, e.g., UOsb2(NO)sb3.6Hsb2O and thus provides radiopaque polymers. Excessive sorption of water lead to phase separation and, hence, loss of radiopacity. Thus, an alternate method of synthesis of radiopaque polymers is also described in which radiopacifying agent is covalently linked to polymer backbone. Styryldiphenylbismuth was prepared by the reaction of diphenylbismuthchloride and Grignard of p-bromostyrene, but some other by-products such as triphenylbismuth, distyrylphenyl bismoth were also obtained as revealed by reverse phase HPLC and the yield of the reaction was low. Iodinated monomers VBTIsb3 and IEMIsb3 were prepared by reacting VBC or IEM to triiodophenol in high yields. Decomposition kinetic analysis was done by

  10. Robust antifogging antireflective coatings on polymer substrates by hydrochloric acid vapor treatment.

    PubMed

    Li, Tong; He, Junhui; Yao, Lin; Geng, Zhi

    2015-04-15

    Antireflective coatings on polymer substrates have received significant attention for their potential applications. In this paper, robust microporous antifogging antireflective coatings on polymer substrates were prepared from acid-catalyzed silica sol followed by hydrochloric acid vapor solidification at mild temperature below glass transition temperatures of common polymers. The coatings passed 3H pencil hardness test, sand flow test and water-drop test. They had excellent antireflective and antifogging properties. The maximum transmittance of coatings on PMMA substrates reached 100.0% (the maximum transmittance wavelength could be regulated) and average transmittance reached 99.0% in 400-800 nm. The advantage and mechanism of hydrochloric acid vapor solidification and mechanical strength enhancement of coatings are discussed in contrast to ammonia vapor treatment and air vapor treatment. The hydrochloric acid vapor treatment results in a dense integrated microporous film structure. Optical properties were characterized by a UV-Vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. Surface morphologies and structures of coatings were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atom force microscopy (AFM).

  11. Synthesis of caffeic acid and p-hydroxybenzoic acid molecularly imprinted polymers and their application for the selective extraction of polyphenols from olive mill waste waters.

    PubMed

    Michailof, Chrysa; Manesiotis, Panagiotis; Panayiotou, Costas

    2008-02-22

    Using caffeic acid and p-hydroxybenzoic acid as templates, two molecularly imprinted polymers (MIPs) were prepared that were used for isolation of polyphenols from olive mill waste water samples (OMWWs) without previous pre-treatment. For the preparation of the caffeic acid MIPs 4-vinylpyridine, allylurea, allylaniline and methacrylic acid were tested as functional monomers, ethylene glycol dimethylacrylate (EDMA), pentaerythritol trimethylacrylate (PETRA) and divinylbenzene 80 (DVB80) as cross-linkers and tetrahydrofuran as porogen. For p-hydroxybenzoic acid 4-vinylpyridine, allylurea and allylaniline were tested as functional monomers, EDMA and PETRA as cross-linkers and acetonitrile as porogen. The performance of the synthesized polymers was evaluated against seven structurally related compounds by means of polymer-based HPLC. The two polymers that presented the most interesting properties were further evaluated by batch rebinding and from the derived isotherms their capacity and binding strength were determined. Using solid-phase extraction (SPE), their ability to recognize and bind the template molecule from an aqueous solution as well as the pH dependence of the binding strength were explored. After establishing the best SPE protocol, an aqueous model mixture of compounds and a raw OMWWs sample were loaded on the two best polymers. The result of the consecutive use of the two polymers on the same sample was explored. It was concluded that acidic conditions favour the recognition abilities of both polymers and that they can be used for a quick and efficient isolation of the polyphenol fraction directly from raw OMWW.

  12. Effect of chain extension on rheology and tensile properties of PHB and PHB-PLA blends

    NASA Astrophysics Data System (ADS)

    Bousfield, Glenn

    Poly(3-hydroxybutyrate), referred to as PHB, is a bacterially-synthesized and biodegradable polymer which is being considered as a substitute for non-biodegradable bulk polymers like polypropylene. PHB is naturally extremely isotactic and naturally has a very high degree of crystallinity, resulting in a stiff but brittle material. The stability of PHB crystals also means that the melting point of the polymer is approximately 170°C, high with respect to similar polymers. For instance, the melting point of poly(4-hydroxybutyrate) is only 53°C (Saito, Nakamura, Hiramitsu, & Doi, 1996). Above 170°C, PHB is subject to a thermomechanical degradation mechanism, meaning that the polymer cannot be melted without degrading. One possible solution to the problem of degradation is to add a chain extender to the molten polymer to increase average molecular weight to counteract the molecular weight lost to degradation. In this work, a variety of chain extenders (JoncrylRTM ADR 4368-C, pyromellitic dianhydride, hexamethylene diisocyanate, polycarbodiimide) were compounded with a random copolymer of 98 mol% 3-hydroxybutyrate and 2 mol% 3-hydroxyvalerate (referred to as PHB) in concentrations ranging from 0.25% to 4%, to determine which chain extender functionality worked best with PHB. Molecular weight change was inferred from torque monitored during compounding, and from complex viscosity determined from parallel-plate rheology. None of the chain extenders changed the rate of degradation of PHB, although Joncryl increased the complex viscosity of the polymer. PHB was also blended with Poly(L-lactic acid), referred to as PLLA in PHB/PLLA ratios of 100/0, 75/25, 50/50, 25/75 and 0/100, to determine the effect of blending on the thermal stability of PHB. Again, thermal stability was determined by monitoring torque during compounding and by measuring complex viscosity through parallel-plate rheology. Blends in which PHB was the more abundant phase, as well as the 50% PHB/50% PLA

  13. Controlled synthesis, optical properties and cytotoxicity studies of CdSe-poly(lactic acid) multifunctional nanocomposites by ring-opening polymerization.

    PubMed

    Islam, Md Rafiqul; Bach, Long Giang; Vo, Thanh-Sang; Lee, Doh C; Lim, Kwon Taek

    2014-08-01

    A facile synthetic route has been developed for the covalent grafting of biocompatible poly(lactic acid) (PLA) onto CdSe Quantum Dots (QDs) using surface initiated ring opening polymerization (ROP) to afford CdSe-g-PLA nanocomposites. At first, 2-mercaptoethanol (ME) capped CdSe QDs were synthesized through a wet chemical process. The surface initiated ROP of lactide was accomplished with Sn(Oct)2 to give CdSe-g-PLA nanocomposites having surface hydroxyl functionality. FT-IR data suggested that a robust covalent bond was formed between ME capped CdSe QDs and polymer moieties. The grafting density of PLA on CdSe QDs was found to be moderate as measured by TGA analysis. The CdSe QDs were well dispersed in CdSe-g-PLA nanocomposites matrices as captured by TEM. The cubic phase crystal structure of CdSe QDs in the nanocomposites was determined by XRD. The optical properties of the CdSe-g-PLA nanocomposites were investigated by UV-vis and photoluminescence spectroscopy which suggested their potentialities as optical materials in biomedical application. Cell viability studies revealed that the biocompatibility of CdSe QDs was improved upon PLA immobilization.

  14. Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

    PubMed

    Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

    2016-02-10

    The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface.

  15. Effect of castor oil enrichment layer produced by reaction on the properties of PLA/HDI-g-starch blends.

    PubMed

    Xiong, Zhu; Zhang, Lisheng; Ma, Songqi; Yang, Yong; Zhang, Chuanzhi; Tang, Zhaobin; Zhu, Jin

    2013-04-15

    Blends of entirely bio-sourced polymers, namely polylactide (PLA) and starch, have been melt-compounded by lab-scale co-extruder with castor oil (CO) as a plasticizer. The enrichment of castor oil on starch had great effect on the properties of the blends. If the castor oil was mainly dispersed in PLA matrix, the properties of the blends were poor, but when the hexamethylenediisocyanate (HDI) was grafted on starch granules the ready reactions between the hydroxyl on CO and the isocyante on the HDI-grafted starch (HGSTs) brought CO molecules enriched on starch particles. DSC analysis shows that the CO layer on starch has a positive effect on the crystallization of PLA in the ternary blend. The accumulation of CO on starch greatly improves the toughness and impact strength of PLA/starch blends. The grafting content of HDI on the starch granules primarily determined the compatibility and properties of the resulted blends.

  16. Relevance of PEG in PLA-based blends for tissue engineering 3D-printed scaffolds.

    PubMed

    Serra, Tiziano; Ortiz-Hernandez, Monica; Engel, Elisabeth; Planell, Josep A; Navarro, Melba

    2014-05-01

    Achieving high quality 3D-printed structures requires establishing the right printing conditions. Finding processing conditions that satisfy both the fabrication process and the final required scaffold properties is crucial. This work stresses the importance of studying the outcome of the plasticizing effect of PEG on PLA-based blends used for the fabrication of 3D-direct-printed scaffolds for tissue engineering applications. For this, PLA/PEG blends with 5, 10 and 20% (w/w) of PEG and PLA/PEG/bioactive CaP glass composites were processed in the form of 3D rapid prototyping scaffolds. Surface analysis and differential scanning calorimetry revealed a rearrangement of polymer chains and a topography, wettability and elastic modulus increase of the studied surfaces as PEG was incorporated. Moreover, addition of 10 and 20% PEG led to non-uniform 3D structures with lower mechanical properties. In vitro degradation studies showed that the inclusion of PEG significantly accelerated the degradation rate of the material. Results indicated that the presence of PEG not only improves PLA processing but also leads to relevant surface, geometrical and structural changes including modulation of the degradation rate of PLA-based 3D printed scaffolds.

  17. Shape-Memory Polymers Based on Fatty Acid-Filled Elastomeric Ionomers

    NASA Astrophysics Data System (ADS)

    Izzo, Elise; Weiss, Robert

    2009-03-01

    Shape memory polymers (SMPs) have applications as medical devices, actuators, sensors, artificial muscles, switches, smart textiles, and self-deployable structures. All previous design of SMPs has involved synthesizing new polymers or modifying existing polymers. This paper describes a new type of SMP based on blends of an elastomeric ionomer and low molar mass fatty acids or their salts (FAS). Shape memory elastomers were prepared from mixtures of a sulfonated EPDM ionomer and various amounts of a FAS (e.g., zinc stearate, zinc oleate, and various aliphalic acids). Nanophase separation of the metal sulfonate groups provided the ``permanent'' crosslinks, while sub-microscopic crystals of the low molecular weight FAS provided a physical crosslink needed for the temporary shape. The material was deformed above the melting point of the FAS and the new shape was fixed by cooling the material while under stress to below the melting point of the FAS. Polar interactions between the ionomer and the FAS stabilized the dispersion of the FAS in the polymer and provided the continuity between the phases that allowed the crystals of the FAS to provide a second network of physical crosslinks. The temporary shape was erased and the material returned to the primary shape by heating above the melting point of the FAS.

  18. Accurate determination of residual acrylic acid in superabsorbent polymer of hygiene products by headspace gas chromatography.

    PubMed

    Zhang, Shu-Xin; Chai, Xin-Sheng; Jiang, Ran

    2017-02-17

    This work reports on a method for the determination of residual acrylic acid (AA) in the superabsorbent polymers for hygiene products by headspace analysis. It was based on water extraction for the polymer sample at a room temperature for 50min. Then, the AA in the extractant reacted with bicarbonate solution in a closed headspace sample vial, from which the carbon dioxide generated from the reaction (within 20min at 70°C) was detected by gas chromatography (GC). It was found that there is adsorption partition equilibrium of AA between solid-liquid phases. Therefore, an equation for calculating the total AA content in the original polymers sample was derived based on the above phase equilibrium. The results show that the HS-GC method has good precision (RSD<2.51%) and good accuracy (recoveries from 93 to 105%); the limit of quantification (LOQ) was 373mg/kg. The present method is rapid, accurate, and suitable for determining total residual acrylic acid in a wide variety of applications from processing of superabsorbent polymer to commercial products quality control.

  19. Neutralisation of the pharmacological activities of Bothrops alternatus venom by anti-PLA2 IgGs.

    PubMed

    Garcia Denegri, María E; Maruñak, Silvana; Todaro, Juan S; Ponce-Soto, Luis A; Acosta, Ofelia; Leiva, Laura

    2014-08-01

    Basic phospholipases A2 (PLA2) are toxic and induce a wide spectrum of pharmacological effects, although the acidic enzyme types are not lethal or cause low lethality. Therefore, it is challenging to elucidate the mechanism of action of acidic phospholipases. This study used the acidic non-toxic Ba SpII RP4 PLA2 from Bothrops alternatus as an antigen to develop anti-PLA2 IgG antibodies in rabbits and used in vivo assays to examine the changes in crude venom when pre-incubated with these antibodies. Using Ouchterlony and western blot analyses on B. alternatus venom, we examined the specificity and sensitivity of phospholipase A2 recognition by the specific antibodies (anti-PLA2 IgG). Neutralisation assays using a non-toxic PLA2 antigen revealed unexpected results. The (indirect) haemolytic activity of whole venom was completely inhibited, and all catalytically active phospholipases A2 were blocked. Myotoxicity and lethality were reduced when the crude venom was pre-incubated with anti-PLA2 immunoglobulins. CK levels in the skeletal muscle were significantly reduced at 6 h, and the muscular damage was more significant at this time-point compared to 3 and 12 h. When four times the LD50 was used (224 μg), half the animals treated with the venom-anti PLA2 IgG mixture survived after 48 h. All assays performed with the specific antibodies revealed that Ba SpII RP4 PLA2 had a synergistic effect on whole-venom toxicity. IgG antibodies against the venom of the Argentinean species B. alternatus represent a valuable tool for elucidation of the roles of acidic PLA2 that appear to have purely digestive roles and for further studies on immunotherapy and snake envenoming in affected areas in Argentina and Brazil.

  20. Influence of natural humic acids and synthetic phenolic polymers on fibrinolysis

    NASA Astrophysics Data System (ADS)

    Klöcking, Hans-Peter

    The influence of synthetic and natural phenolic polymers on the release of plasminogen activator was studied in an isolated, perfused, vascular preparation (pig ear). Of the tested synthetic phenolic polymers, the oxidation products of caffeic acid (KOP) and 3,4-dihydroxyphenylacetic acid (3,4-DHPOP), at a concentration of 50 µg/ml perfusate, were able to increase the plasminogen activator activity by 70%. The oxidation products of chlorogenic acid (CHOP), hydrocaffeic acid (HYKOP), pyrogallol (PYROP) and gallic acid (GALOP), at the same concentration, exerted no influence on the release of plasminogen activator. Of the naturally occurring humic acids, the influence of sodium humate was within the same order of magnitude as KOP and 3,4-DHPOP. Ammonium humate was able to increase the plasminogen activator release only at a concentration of 100 µg/ml perfusate. In rats, the t-PA activity increased after i.v. application of 10 mg/kg of KOP, Na-HS or NH4-HS.

  1. An Optically Active Polymer for Broad-Spectrum Enantiomeric Recognition of Chiral Acids.

    PubMed

    Yan, Jijun; Kang, Chuanqing; Bian, Zheng; Ma, Xiaoye; Jin, Rizhe; Du, Zhijun; Gao, Lianxun

    2017-03-14

    Recognition of enantiomers of chiral acids by anion-π or lone pair-π interactions has not yet been investigated but is a significant and attractive challenge. This study reports an optically active polymer-based supramolecular system with capabilities of discriminating enantiomers of various chiral acids. The polymer featuring alternate π-acidic naphthalenediimides (NDIs) and methyl l-phenylalaninates in the backbone exhibits an unprecedented slow self-assembly process that is susceptible to perturbation by various chiral acids. Thus, the combination of anion-π or lone pair-π interactions and sensitivity of the polymeric self-assembly process to external chiral species endows the system with recognition capabilities. This is the first time that anion-π or lone pair-π interactions have been applied in the recognition of enantiomers of various chiral acids with a single system. The results shed light on new strategies for material design by integrating π-acidic aromatic systems and chiral building blocks to afford relevant advanced functions.

  2. Synthesis of Novel N9-Substituted Purine Derivatives from Polymer Supported α-Amino Acids.

    PubMed

    Vanda, David; Jorda, Radek; Lemrová, Barbora; Volná, Tereza; Kryštof, Vladimír; McMaster, Claire; Soural, Miroslav

    2015-07-13

    Solid-phase synthesis of purine derivatives bearing an α-amino acid motif in position 9 is described herein. Polymer supported amines were acylated with various Fmoc-α-amino acids and, after cleavage of the protecting group, arylation with 4,6-dichloro-5-nitropyrimidine or 2,4-dichloro-5-nitropyrimidine was performed. The second chlorine atom was replaced with various amines. Subsequent reduction of the nitro group, followed by reaction with aldehydes, afforded the purine scaffold. After cleavage from the polymer support, the target compounds were obtained in very good crude purity, good overall yields, and excellent enantiomeric purity. The anticancer activity of prepared compounds was tested in vitro against human cancer cell lines MCF7 and K562, and they were found to have mild, but clear dose-dependent effects.

  3. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2... 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2'-(1,2-diazenediyl)bis - and...

  4. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fatty acid, reaction product with... Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted oxirane, formaldehyde... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  5. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acid, reaction product with... Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted oxirane, formaldehyde... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  6. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acid, reaction product with... Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted oxirane, formaldehyde... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  7. Salicylic Acid-Based Polymers for Guided Bone Regeneration Using Bone Morphogenetic Protein-2

    PubMed Central

    Subramanian, Sangeeta; Mitchell, Ashley; Yu, Weiling; Snyder, Sabrina; Uhrich, Kathryn

    2015-01-01

    Bone morphogenetic protein-2 (BMP-2) is used clinically to promote spinal fusion, treat complex tibia fractures, and to promote bone formation in craniomaxillofacial surgery. Excessive bone formation at sites where BMP-2 has been applied is an established complication and one that could be corrected by guided tissue regeneration methods. In this study, anti-inflammatory polymers containing salicylic acid [salicylic acid-based poly(anhydride-ester), SAPAE] were electrospun with polycaprolactone (PCL) to create thin flexible matrices for use as guided bone regeneration membranes. SAPAE polymers hydrolyze to release salicylic acid, which is a nonsteroidal anti-inflammatory drug. PCL was used to enhance the mechanical integrity of the matrices. Two different SAPAE-containing membranes were produced and compared: fast-degrading (FD-SAPAE) and slow-degrading (SD-SAPAE) membranes that release salicylic acid at a faster and slower rate, respectively. Rat femur defects were treated with BMP-2 and wrapped with FD-SAPAE, SD-SAPAE, or PCL membrane or were left unwrapped. The effects of different membranes on bone formation within and outside of the femur defects were measured by histomorphometry and microcomputed tomography. Bone formation within the defect was not affected by membrane wrapping at BMP-2 doses of 12 μg or more. In contrast, the FD-SAPAE membrane significantly reduced bone formation outside the defect compared with all other treatments. The rapid release of salicylic acid from the FD-SAPAE membrane suggests that localized salicylic acid treatment during the first few days of BMP-2 treatment can limit ectopic bone formation. The data support development of SAPAE polymer membranes for guided bone regeneration applications as well as barriers to excessive bone formation. PMID:25813520

  8. Salicylic Acid-Based Polymers for Guided Bone Regeneration Using Bone Morphogenetic Protein-2.

    PubMed

    Subramanian, Sangeeta; Mitchell, Ashley; Yu, Weiling; Snyder, Sabrina; Uhrich, Kathryn; O'Connor, J Patrick

    2015-07-01

    Bone morphogenetic protein-2 (BMP-2) is used clinically to promote spinal fusion, treat complex tibia fractures, and to promote bone formation in craniomaxillofacial surgery. Excessive bone formation at sites where BMP-2 has been applied is an established complication and one that could be corrected by guided tissue regeneration methods. In this study, anti-inflammatory polymers containing salicylic acid [salicylic acid-based poly(anhydride-ester), SAPAE] were electrospun with polycaprolactone (PCL) to create thin flexible matrices for use as guided bone regeneration membranes. SAPAE polymers hydrolyze to release salicylic acid, which is a nonsteroidal anti-inflammatory drug. PCL was used to enhance the mechanical integrity of the matrices. Two different SAPAE-containing membranes were produced and compared: fast-degrading (FD-SAPAE) and slow-degrading (SD-SAPAE) membranes that release salicylic acid at a faster and slower rate, respectively. Rat femur defects were treated with BMP-2 and wrapped with FD-SAPAE, SD-SAPAE, or PCL membrane or were left unwrapped. The effects of different membranes on bone formation within and outside of the femur defects were measured by histomorphometry and microcomputed tomography. Bone formation within the defect was not affected by membrane wrapping at BMP-2 doses of 12 μg or more. In contrast, the FD-SAPAE membrane significantly reduced bone formation outside the defect compared with all other treatments. The rapid release of salicylic acid from the FD-SAPAE membrane suggests that localized salicylic acid treatment during the first few days of BMP-2 treatment can limit ectopic bone formation. The data support development of SAPAE polymer membranes for guided bone regeneration applications as well as barriers to excessive bone formation.

  9. Partial replacement effect of montmorillonite with cellulose nanowhiskers on polylactic acid nanocomposites.

    PubMed

    Arjmandi, Reza; Hassan, Azman; Mohamad Haafiz, M K; Zakaria, Zainoha

    2015-11-01

    In this study, hybrid montmorillonite/cellulose nanowhiskers (MMT/CNW) reinforced polylactic acid (PLA) nanocomposites were produced through solution casting. The CNW filler was first isolated from microcrystalline cellulose by chemical swelling technique. The partial replacement of MMT with CNW in order to produce PLA/MMT/CNW hybrid nanocomposites was performed at 5 parts per hundred parts of polymer (phr) fillers content, based on highest tensile strength values as reported in our previous study. MMT were partially replaced with various amounts of CNW (1, 2, 3, 4 and 5phr). The tensile, thermal, morphological and biodegradability properties of PLA hybrid nanocomposites were investigated. The highest tensile strength of hybrid nanocomposites was obtained with the combination of 4phr MMT and 1phr CNW. Interestingly, the ductility of hybrid nanocomposites increased significantly by 79% at this formulation. The Young's modulus increased linearly with increasing CNW content. Thermogravimetric analysis illustrated that the partial replacement of MMT with CNW filler enhanced the thermal stability of the PLA. This is due to the relatively good dispersion of fillers in the hybrid nanocomposites samples as revealed by transmission electron microscopy. Interestingly, partial replacements of MMT with CNW improved the biodegradability of hybrid nanocomposites compared to PLA/MMT and neat PLA.

  10. Polylactic acid with improved heat deflection temperatures and self-healing properties for durable goods applications.

    PubMed

    Wertz, J T; Mauldin, T C; Boday, D J

    2014-11-12

    A method to recover fracture toughness after failure and increase thermal properties of polylactic acid (PLA) for use within durable goods applications is presented. Microcapsules were incorporated into PLA to form a composite material in which the microcapsules served the dual purpose of (1) releasing self-healing additives to fracture regions and (2) serving as nucleating agents to improve the PLA composite's thermal tolerance. Self-healing was achieved though embedment of dicyclopentadiene-filled microcapsules and Grubbs' first generation ruthenium metathesis catalyst, the former being autonomically released into damage volumes and undergoing polymerization in the presence of the catalyst. This approach led to up to 84% recovery of the polymer composite's initial fracture toughness. Additionally, PLA's degree of crystallinity and heat deflection temperature were improved by ∼ 11% and ∼ 21 °C, respectively, relative to nonfilled virgin PLA, owing to microcapsule-induced nucleation. The self-healing system developed here overcomes many property limitations of PLA that can potentially lead to its incorporation into various durable goods.

  11. Photopatterned collagen-hyaluronic acid interpenetrating polymer network hydrogels.

    PubMed

    Suri, Shalu; Schmidt, Christine E

    2009-09-01

    To engineer complex tissues, it is necessary to create hybrid scaffolds with micropatterned structural and biomechanical properties, which can closely mimic the intricate body tissues. The current report describes the synthesis of a novel photocrosslinkable interpenetrating polymeric network (IPN) of collagen and hyaluronic acid (HA) with precisely controlled structural and biomechanical properties. Both collagen and HA are present in crosslinked form in IPNs, and the two networks are entangled with each other. IPNs were also compared with semi-IPNs (SIPN), in which only collagen was in network form and HA chains were entangled in the collagen network without being photocrosslinked. Scanning electron microscopy images revealed that IPNs are denser than SIPNs, which results in their molecular reinforcement. This was further confirmed by rheological experiments. Because of the presence of the HA crosslinked network, the storage modulus of IPNs was almost two orders of magnitude higher than SIPNs. The degradation of the collagen-HA IPNs was slower than the SIPNs because of the presence of the crosslinked HA network. Increasing concentration of HA further altered the properties among IPNs. Cytocompatibility of IPNs was confirmed by Schwann cell and dermal fibroblasts adhesion and proliferation studies. We also fabricated patterned scaffolds with regions of IPNs and SIPNs within a bulk hydrogel, resulting in zonal distribution of crosslinking densities, viscoelasticities, water content and pore sizes at the micro- and macro-scales. With the ability to fine-tune the scaffold properties by performing structural modifications and to create patterned scaffolds, these hydrogels can be employed as potential candidates for regenerative medicine applications.

  12. Monolithic calcium phosphate/poly(lactic acid) composite versus calcium phosphate-coated poly(lactic acid) for support of osteogenic differentiation of human mesenchymal stromal cells.

    PubMed

    Tahmasebi Birgani, Zeinab; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-03-01

    Calcium phosphates (CaPs), extensively used synthetic bone graft substitutes, are often combined with other materials with the aim to overcome issues related to poor mechanical properties of most CaP ceramics. Thin ceramic coatings on metallic implants and polymer-ceramic composites are examples of such hybrid materials. Both the properties of the CaP used and the method of incorporation into a hybrid structure are determinant for the bioactivity of the final construct. In the present study, a monolithic composite comprising nano-sized CaP and poly(lactic acid) (PLA) and a CaP-coated PLA were comparatively investigated for their ability to support proliferation and osteogenic differentiation of bone marrow-derived human mesenchymal stromal cells (hMSCs). Both, the PLA/CaP composite, produced using physical mixing and extrusion and CaP-coated PLA, resulting from a biomimetic coating process at near-physiological conditions, supported proliferation of hMSCs with highest rates at PLA/CaP composite. Enzymatic alkaline phosphatase activity as well as the mRNA expression of bone morphogenetic protein-2, osteopontin and osteocalcin were higher on the composite and coated polymer as compared to the PLA control, while no significant differences were observed between the two methods of combining CaP and PLA. The results of this study confirmed the importance of CaP in osteogenic differentiation while the exact properties and the method of incorporation into the hybrid material played a less prominent role.

  13. Annealing free, clean graphene transfer using alternative polymer scaffolds

    NASA Astrophysics Data System (ADS)

    Wood, Joshua D.; Doidge, Gregory P.; Carrion, Enrique A.; Koepke, Justin C.; Kaitz, Joshua A.; Datye, Isha; Behnam, Ashkan; Hewaparakrama, Jayan; Aruin, Basil; Chen, Yaofeng; Dong, Hefei; Haasch, Richard T.; Lyding, Joseph W.; Pop, Eric

    2015-02-01

    We examine the transfer of graphene grown by chemical vapor deposition (CVD) with polymer scaffolds of poly(methyl methacrylate) (PMMA), poly(lactic acid) (PLA), poly(phthalaldehyde) (PPA), and poly(bisphenol A carbonate) (PC). We find that optimally reactive PC scaffolds provide the cleanest graphene transfers without any annealing, after extensive comparison with optical microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, and scanning tunneling microscopy. Comparatively, films transferred with PLA, PPA, PMMA/PC, and PMMA have a two-fold higher roughness and a five-fold higher chemical doping. Using PC scaffolds, we demonstrate the clean transfer of CVD multilayer graphene, fluorinated graphene, and hexagonal boron nitride. Our annealing free, PC transfers enable the use of atomically-clean nanomaterials in biomolecule encapsulation and flexible electronic applications.

  14. Inhibition of phospholipase A2 (PLA2) activity by nifedipine and nisoldipine is independent of their calcium-channel-blocking activity

    SciTech Connect

    Chang, J.; Blazek, E.; Carlson, R.P.

    1987-09-01

    The effects of several calcium antagonists on phospholipase A2 (PLA2) activity were examined. Nifedipine and nisoldipine inhibited a cell-free preparation of PLA2 in a dose-dependent manner with maximal inhibition of 71-77% observed at 100 microM. More potent or equipotent dihydropyridine calcium antagonists such as nitrendipine and felodipine did not inhibit PLA2 activity. In addition, nondihydropyridine calcium antagonists such as diltiazem, verapamil, and cinnarazine failed to reduce PLA2 activity markedly. Nifedipine and nisoldipine also reduced PLA2 activity in intact mouse peritoneal macrophages where PLA2 activity was monitored by free (/sup 14/C)arachidonic acid release from (/sup 14/C)arachidonic acid-prelabeled cells. When levels of PGE2 and LTC4 were measured by radioimmunoassay, it was found that the synthesis of these two metabolites was concomitantly inhibited by nifedipine and nisoldipine. In vivo, nifedipine and nisoldipine inhibited tetradecanoylphorbol acetate (TPA) induced ear edema. UV irradiation of nifedipine and nisoldipine (which destroys the slow calcium-channel-blocking activity of these compounds) did not result in a loss of PLA2 inhibitory activity. In fact, in both instances the UV-irradiated forms of nifedipine and nisoldipine were slightly more potent PLA2 inhibitors than the parent compound alone. We therefore conclude that the ability of nifedipine and nisoldipine to inhibit PLA2 was direct and unrelated to their actions on slow calcium channels.

  15. In situ preparation of powder and the sorption behaviors of molecularly imprinted polymers through the complexation between polymer ion of methyl methacrylate/acrylic acid and Ca++ ion.

    PubMed

    Chough, Sung Hyo; Park, Kwang Ho; Cho, Seung Jin; Park, Hye Ryoung

    2014-09-02

    Molecularly imprinted polymer (MIP) powders were prepared using a simple complexation strategy between the polymer carboxylate groups and template molecule followed by metal cation cross-linking of residual polymer carboxylates. Polymer powders were formed in situ by templating carboxylic acid containing polymers with 4-ethylaniline (4-EA), followed by addition of an aqueous CaCl2 solution. The solution remained homogeneous. The powders were prepared by precipitation by slowly adding a non-solvent, H2O, to the mixture. The resulting particles were very porous with uptake capacity that approached the theoretical value. We suggest two types of complexes are formed between the template, 4-EA, and polymer. The isolated entry type forms well defined cavities for the template with high specific selectivity, while the adjacent entry type forms wider binding sites without specific sorption for isomeric molecules. To evaluate conditions for forming materials with high affinity and selectivity, three MIPs were prepared containing 0.5, 1.0, and 1.5 equivalents of template to the base polymer. The MIP containing 0.5 eq showed higher specific selectivity to 4-EA, but the MIP containing 1.5 eq had noticeably lower selectivity. The lower selectivity is attributed to poorly formed binding sites with little selective sorption to any isomer when the higher ratio of template was used. However at the lower ratio of template the isolated entry is preferably formed to produce well defined binding cavities with higher selectivity to template.

  16. Deep Eutectic Solvents Modified Molecular Imprinted Polymers for Optimized Purification of Chlorogenic Acid from Honeysuckle.

    PubMed

    Li, Guizhen; Wang, Wei; Wang, Qian; Zhu, Tao

    2016-02-01

    Deep eutectic solvents (DES) were synthesized with choline chloride (ChCl), and DES modified molecular imprinted polymers (DES-MIPs), DES modified non-imprinted polymers (DES-NIPs, without template), MIPs and NIPs were prepared in an identical procedure. Fourier transform infrared spectrometer (FT-IR) and field emission scanning electron microscopy (FE-SEM) were used to characterize the obtained polymers. Rebinding experiment and solid-phase extraction (SPE) were used to prove the high selectivity adsorption properties of the polymers. Box-Behnken design (BBD) with three factors was used to optimize the extraction condition of chlorogenic acid (CA) from honeysuckles. The optimum extraction conditions were found to be ultrasonic time optimized (20 min), the volume fraction of ethanol (60%) and ratio of liquid to material (15 mL g(-1)). Under these conditions, the mean extraction yield of CA was 12.57 mg g(-1), which was in good agreement with the predicted BBD model value. Purification of hawthorn extract was achieved by SPE process, and SPE recoveries of CA were 72.56, 64.79, 69.34 and 60.08% by DES-MIPs, DES-NIPs, MIPs and NIPs, respectively. The results showed DES-MIPs had potential for promising functional adsorption material for the purification of bioactive compounds.

  17. Effect of applying modes of the polymer microneedle-roller on the permeation of L-ascorbic acid in rats.

    PubMed

    You, Sung-Kyun; Noh, Young-Wook; Park, Hyoun-Hyang; Han, Manhee; Lee, Seung S; Shin, Sang-Chul; Cho, Cheong-Weon

    2010-01-01

    Despite the advantages of drug delivery through skin, transdermal drug delivery is only used with a small subset of drugs because most compounds cannot cross the skin at therapeutically useful rates. Recently, a new concept known as microneedle was introduced and could be used to pierce effectively to deliver drugs using micron-sized needles in a minimally invasive and painless manner. In this study, the polymer microneedle-roller was fabricated so that it can be applied into the permeation of L-ascorbic acid. Moreover, a recent publication suggested the possibility of ascorbic acid 2-phosphate as a hair restorer; hence, this study was carried out to check the effect of L-ascorbic acid itself on the hair growing rate in rats according to the presence of various application frequencies of the polymer microneedle-roller. When the polymer microneedle-roller was applied nine times with four directions into rat's shaved skin, the permeation of L-ascorbic acid increased by 10.54-fold compared to that of the absence of the polymer microneedle-roller. The histological examination revealed that the skin pretreated with various application frequencies of the polymer microneedle-roller had more transport pathways. The faster hair growing phenomenon was observed in the presence of polymer microneedle-roller compared to the absence of the polymer microneedle-roller.

  18. Development of degradable renewable polymers and stimuli-responsive nanocomposites

    NASA Astrophysics Data System (ADS)

    Eyiler, Ersan

    The overall goal of this research was to explore new living radical polymerization methods and the blending of renewable polymers. Towards this latter goal, polylactic acid (PLA) was blended with a new renewable polymer, poly(trimethylene-malonate) (PTM), with the aim of improving mechanical properties, imparting faster degradation, and examining the relationship between degradation and mechanical properties. Blend films of PLA and PTM with various ratios (5, 10, and 20 wt %) were cast from chloroform. Partially miscible blends exhibited Young's modulus and elongation-to-break values that significantly extend PLA's usefulness. Atomic force microscopy (AFM) data showed that incorporation of 10 wt% PTM into PLA matrix exhibited a Young's modulus of 4.61 GPa, which is significantly higher than that of neat PLA (1.69 GPa). The second part of the bioplastics study involved a one-week hydrolytic degradation study of PTM and another new bioplastic, poly(trimethylene itaconate) (PTI) using DI water (pH 5.4) at room temperature, and the effects of degradation on crystallinity and mechanical properties of these films were examined by differential scanning calorimetry (DSC) and AFM. PTI showed an increase in crystallinity with degradation, which was attributed to predominately degradation of free amorphous regions. Depending on the crystallinity, the elastic modulus increased at first, and decreased slightly. Both bulk and surface-tethered stimuli-responsive polymers were studied on amine functionalized magnetite (Fe3O4) nanoparticles. Stimuli-responsive polymers studied, including poly(N-isopropylacrylamide) (PNIPAM), poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), and poly(itaconic acid) (PIA), were grafted via surface-initiated aqueous atom transfer radical polymerization (SI-ATRP). Both Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) spectroscopies showed the progression of the grafting. The change in particle size as a

  19. Non-isothermal crystallization kinetics in melt-drawn PCL/PLA microfibrillar composites

    NASA Astrophysics Data System (ADS)

    Kratochvíl, Jaroslav; Kelnar, Ivan

    2016-05-01

    The non-isothermal crystallization kinetics of the system poly(ɛ-caprolactone)/poly(lactic acid)/clay C15 and related microfibrillar composites has been studied using a simple method based on mathematical treatment of the DSC cumulative crystallization curves in their inflection point. The method provides three kinetic parameters: temperature of start of crystallization, temperature of maximum crystallization rate, and numerical value of the maximum crystallization rate. In the range of cooling rates 5 - 20°C/min, the temperatures of crystallization start and of maximum crystallization rate are determined with standard deviation of 0.3 and 0.4°C, respectively. Average standard deviation of maximum crystallization rate is 1.0 K-1 corresponding to coefficient of variation 5.8 %. Repeatability is slightly better at lower cooling rates. The modified samples show intensive nucleation effect during the non-isothermal crystallization, as demonstrated by their values of temperatures of crystallization start and of maximum crystallization rate that are significantly higher than that of neat PCL. The highest maximum crystallization rate has been found for the blend PCL/PLA 80/20. The proposed method does not refer to any crystallization model and does not require exact determination of the starting point of crystallization. On the other hand, it does not provide any information about dimensionality of crystal growth. The method is particularly useful for characterizing a series of samples derived by modification of the neat polymer.

  20. Novel conducting polymer-heteropoly acid hybrid material for artificial photosynthetic membranes.

    PubMed

    McDonald, Michael B; Freund, Michael S

    2011-04-01

    Artificial photosynthetic (AP) approaches to convert and store solar energy will require membranes capable of conducting both ions and electrons while remaining relatively transparent and chemically stable. A new approach is applied herein involving previously described in situ chemical polymerization of electronically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of proton conducting heteropoly acid (HPA) phosphomolybdic acid (PMA). The electrochemical behaviour of the PEDOT/PMA hybrid material was investigated and it was found that the conducting polymer (CP) is susceptible to irreversible oxidative processes at potentials where water is oxidized. This will be problematic in AP devices should the process occur in very close proximity to a conducting polymer-based membrane. It was found that PEDOT grants the system good electrical performance in terms of conductivity and stability over a large pH window; however, the presence of PMA was not found to provide sufficient proton conductivity. This was addressed in an additional study by tuning the ionic (and in turn, electronic) conductivity in creating composites with the proton-permselective polymer Nafion. It was found that a material of this nature with near-equal conductivity for optimal chemical conversion efficiency will consist of roughly three parts Nafion and one part PEDOT/PMA.

  1. Facile synthesis of acid-labile polymers with pendent ortho esters.

    PubMed

    Cheng, Jing; Ji, Ran; Gao, Shi-Juan; Du, Fu-Sheng; Li, Zi-Chen

    2012-01-09

    This work presents a facile approach for preparation of acid-labile and biocompatible polymers with pendent cyclic ortho esters, which is based on the efficient and mild reactions between cyclic ketene acetal (CKA) and hydroxyl groups. Three CKAs, 2-ethylidene-1,3-dioxane (EDO), 2-ethylidene-1,3-dioxolane (EDL), and 2-ethylidene-4- methyl-1,3-dioxolane (EMD) were prepared from the corresponding cyclic vinyl acetals by catalytic isomerization of the double bond. The reaction of CKAs with different alcohols and diols was examined using trace of p-toluenesulfonic acid as a catalyst. For the monohydroxyl alcohols, cyclic ortho esters were formed by simple addition of the hydroxyl group toward CKAs with ethanol showing a much greater reactivity than iso-propanol. When 1,2- or 1,3-diols were used to react with the CKAs, we observed the isomerized cyclic ortho esters besides the simple addition products. Biocompatible polyols, that is, poly(2-hydroxyethyl acrylate) (PHEA) and poly(vinyl alcohol) (PVA) were then modified with CKAs, and the degree of substitution of the pendent ortho esters can be easily tuned by changing feed ratio. Both the small molecule ortho esters and the CKA-modified polymers demonstrate the pH-dependent hydrolysis profiles, which depend also on the chemical structure of the ortho esters as well as the polymer hydrophobicity.

  2. Effect of polymer species and concentration on the production of mefenamic acid nanoparticles by media milling.

    PubMed

    Ito, Atsutoshi; Konnerth, Christoph; Schmidt, Jochen; Peukert, Wolfgang

    2016-01-01

    The effect of four structurally different polymer species (hydroxypropylcellulose, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer and polyvinyl alcohol) on the production of mefenamic acid nanoparticles during media milling has been studied. It was found that product particle sizes are strongly determined by the type of polymeric stabiliser as well as by its concentration at constant process conditions. With respect to small product particle sizes an optimum excipient concentration was identified and adjusted for colloidal stability of the drug nanosuspensions. Furthermore, it was found that overdosing of excipients must be omitted to suppress ripening due to enhanced solubilisation phenomena. Hence, the smallest product particle sizes were obtained using a polymeric stabiliser which exhibits a high affinity to the model drug compound and a low solubilisation capacity. Affinities of each polymer species to mefenamic acid and corresponding surface concentrations were determined using straightforward and simple viscosity measurements of the supernatant. A relationship between polymer affinity, solubilisation capacity and limiting product particle size has been observed, which supports the hypothesis that final product particle sizes are rather determined by the solid-liquid equilibrium than by pure mechanical fracture.

  3. Synthesis and characterization of polymer brushes that can be cleaved from the substrate by photo-generated acid

    NASA Astrophysics Data System (ADS)

    Montague, Martha; Edwards, Erik; Nealey, Paul

    2003-03-01

    An established method for synthesizing monodisperse polymer brushes is to deposit a monolayer of "living" free radical initiator molecules and to polymerize the brushes from the substrate. We have developed a method for patterning these brushes by incorporating an acid-labile linkage into the tether that allows the brushes to be cleaved from the surface by exposing them to Extreme Ultra-Violet radiation in the presence of a photo-acid generator. A number of acid-labile linkages were studied, including a wide range of reactivities to acid. The reaction of the acid labile linkage to acid was monitored using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS). Only the most reactive linkage, a menthyl carbonate linkage, could be cleaved by the photo-acid. The polymer brushes containing the acid labile linkage were studied as imaging layers in terms of resolution and sensitivity.

  4. α-Amino acid containing degradable polymers as functional biomaterials: rational design, synthetic pathway, and biomedical applications.

    PubMed

    Sun, Huanli; Meng, Fenghua; Dias, Aylvin A; Hendriks, Marc; Feijen, Jan; Zhong, Zhiyuan

    2011-06-13

    Currently, biomedical engineering is rapidly expanding, especially in the areas of drug delivery, gene transfer, tissue engineering, and regenerative medicine. A prerequisite for further development is the design and synthesis of novel multifunctional biomaterials that are biocompatible and biologically active, are biodegradable with a controlled degradation rate, and have tunable mechanical properties. In the past decades, different types of α-amino acid-containing degradable polymers have been actively developed with the aim to obtain biomimicking functional biomaterials. The use of α-amino acids as building units for degradable polymers may offer several advantages: (i) imparting chemical functionality, such as hydroxyl, amine, carboxyl, and thiol groups, which not only results in improved hydrophilicity and possible interactions with proteins and genes, but also facilitates further modification with bioactive molecules (e.g., drugs or biological cues); (ii) possibly improving materials biological properties, including cell-materials interactions (e.g., cell adhesion, migration) and degradability; (iii) enhancing thermal and mechanical properties; and (iv) providing metabolizable building units/blocks. In this paper, recent developments in the field of α-amino acid-containing degradable polymers are reviewed. First, synthetic approaches to prepare α-amino acid-containing degradable polymers will be discussed. Subsequently, the biomedical applications of these polymers in areas such as drug delivery, gene delivery and tissue engineering will be reviewed. Finally, the future perspectives of α-amino acid-containing degradable polymers will be evaluated.

  5. Cathepsin B-sensitive polymers for compartment-specific degradation and nucleic acid release

    PubMed Central

    Chu, David S.H.; Johnson, Russell N.; Pun, Suzie H.

    2011-01-01

    Degradable cationic polymers are desirable for in vivo nucleic acid delivery because they offer significantly decreased toxicity over non-degradable counterparts. Peptide linkers provide chemical stability and high specificity for particular endopeptidases but have not been extensively studied for nucleic acid delivery applications. In this work, enzymatically degradable peptide-HPMA copolymers were synthesized by RAFT polymerization of HPMA with methacrylated peptide macromonomers, resulting in polymers with low polydispersity and near quantitative incorporation of peptides. Three peptide-HPMA copolymers were evaluated: (i) pHCathK10, containing peptides composed of the linker phe-lys-phe-leu (FKFL), a substrate of the endosomal/lysosomal endopeptidase cathepsin B, connected to oligo-(l)-lysine for nucleic acid binding, (ii) pHCath(d)K10, containing the FKFL linker with oligo-(d)-lysine, and (iii) pH(d)Cath(d)K10, containing all (d) amino acids. Cathepsin B degraded copolymers pHCathK10 and pHCath(d)K10 within one hour while no degradation of pH(d)Cath(d)K10 was observed. Polyplexes formed with pHCathK10 copolymers show DNA release by 4 hrs of treatment with cathepsin B; comparatively, polyplexes formed with pHCath(d)K10 and pH(d)Cath(d)K10 show no DNA release within 8 hrs. Transfection efficiency in HeLa and NIH/3T3 cells were comparable between the copolymers but pHCathK10 was less toxic. This work demonstrates the successful application of peptide linkers for degradable cationic polymers and DNA release. PMID:22036879

  6. A report on emergent uranyl binding phenomena by an amidoxime phosphonic acid co-polymer

    SciTech Connect

    Abney, C. W.; Das, S.; Mayes, R. T.; Kuo, L. -J.; Wood, J.; Gill, G.; Piechowicz, M.; Lin, Z.; Lin, W.; Dai, S.

    2016-01-01

    The development of technology to harvest the uranium dissolved in seawater would enable access to vast quantities of this critical metal for nuclear power generation. Amidoxime polymers are the most promising platforms for achieving this separation, yet the design of advanced adsorbents is hindered by uncertainty regarding the uranium binding mode. In this work we use XAFS to investigate the uranium coordination environment in an amidoxime–phosphonic acid copolymer adsorbent. In contrast to the binding mode predicted computationally and from small molecule studies, a cooperative chelating model is favoured, attributable to emergent behavior resulting from inclusion of amidoxime in the polymer. Samples exposed to seawater also display a feature consistent with a μ2-oxo-bridged transition metal, suggesting the formation of an in situ specific binding site. These findings challenge long held assumptions and provide new opportunities for the design of advanced adsorbent materials.

  7. Formation of Gd coordination polymer with 1D chains mediated by Bronsted acidic ionic liquids

    NASA Astrophysics Data System (ADS)

    Luo, Qianqian; Han, Ying; Lin, Hechun; Zhang, Yuanyuan; Duan, Chungang; Peng, Hui

    2017-03-01

    One dimensional coordination polymer Gd[(SO4)(NO3)(C2H6SO)2] (1) is prepared through the mediation of Bronsted acid ionic liquid, which crystallized in the monoclinic space of C2/c. In this polymer, adjacent Gd atoms are linked by two SO42- ions to generate a 1-D chain, and all oxygen atoms in SO42- groups are connected to three nearest Gd atoms in μ3:η1:η1:η2 fashion. Gd, S and N from SO42- and NO3- are precisely coplanar. The planar is coordinated by a pair of DMSO molecules, which is parallel and linked by hydrogen bonding to form a three-dimensional supramolecular network. Magnetic susceptibility measurement of 1 reveals weak antiferromagnetic interactions between the Gd (III) ions. It exhibits relatively large magneto-caloric effect with -ΔSm=28.8 J Kg-1 K-1 for ΔH=7 T.

  8. A report on emergent uranyl binding phenomena by an amidoxime phosphonic acid co-polymer

    DOE PAGES

    Abney, C. W.; Das, S.; Mayes, R. T.; ...

    2016-08-01

    Development of technology to harvest the uranium dissolved in seawater would enable access to vast quantities of this critical metal for nuclear power generation. Amidoxime polymers are the most promising platform for achieving this separation, yet design of advanced adsorbents is hindered by uncertainty regarding the uranium binding mode. In this work we use XAFS to investigate the uranium coordination environment in an amidoxime-phosphonic acid copolymer adsorbent. In contrast to the binding mode predicted computationally and from small molecule studies, a cooperative chelating model is favoured, attributable to emergent behavior resulting from inclusion of amidoxime in a polymer. Samples exposedmore » to seawater also display a feature consistent with a 2-oxo-bridged transition metal, suggesting formation of an in situ specific binding site. As a result, these findings challenge long held assumptions and provide new opportunities for the design of advanced adsorbent materials.« less

  9. Two new coordination polymers based on tartaric acid ligand: Syntheses, crystal structure and thermal stability

    NASA Astrophysics Data System (ADS)

    Chen, Fei-Yan; Lan, You-Zhao; Han, Min-Min; Feng, Yun-Long

    2016-09-01

    Two new coordination polymers [Cd3(D-Tar)3]n ( 1) and [Pb( meso-Tar)]n ( 2) (H2 Tar = tartaric acid) have been synthesized by hydrothermal reaction and characterized by single crystal X-ray diffraction analysis and IR spectra. 1 crystallizes in the C2221 chiral space group and shows a 3D (4,4)-connected net with the (4.6.84)4(4.62.82.10)(4.62.83)(4.63.82)(4.63.82)4(4.85)2 topology. 2 possesses a 3D (4,4)-connected net with the (43.62.8) topology. In addition, the thermogravimetric analyses (TGA) results for polymers are discussed.

  10. A report on emergent uranyl binding phenomena by an amidoxime phosphonic acid co-polymer

    SciTech Connect

    Abney, C. W.; Das, S.; Mayes, R. T.; Kuo, L. -J.; Wood, J.; Gill, G.; Piechowicz, M.; Lin, Z.; Lin, W.; Dai, S.

    2016-08-01

    Development of technology to harvest the uranium dissolved in seawater would enable access to vast quantities of this critical metal for nuclear power generation. Amidoxime polymers are the most promising platform for achieving this separation, yet design of advanced adsorbents is hindered by uncertainty regarding the uranium binding mode. In this work we use XAFS to investigate the uranium coordination environment in an amidoxime-phosphonic acid copolymer adsorbent. In contrast to the binding mode predicted computationally and from small molecule studies, a cooperative chelating model is favoured, attributable to emergent behavior resulting from inclusion of amidoxime in a polymer. Samples exposed to seawater also display a feature consistent with a 2-oxo-bridged transition metal, suggesting formation of an in situ specific binding site. As a result, these findings challenge long held assumptions and provide new opportunities for the design of advanced adsorbent materials.

  11. Selective extraction of gallic acid in pomegranate rind using surface imprinting polymers over magnetic carbon nanotubes.

    PubMed

    Hao, Yi; Gao, Ruixia; Liu, Dechun; Tang, Yuhai; Guo, Zengjun

    2015-10-01

    A novel surface imprinting polymer based on magnetic carbon nanotubes was prepared using dendritic polyethyleneimine as functional monomer to amplify the number of imprinted cavities. The characteristics of resulting polymers were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). Results suggest that magnetic nanoparticles are deposited onto the surface of multiwalled carbon nanotubes and the imprinted shell is coated on the surface of magnetic carbon nanotubes with a thickness of approximately 8 nm. Magnetic imprinted polymers are sensitive to magnetic fields and can be easily separated within 3 s using an external magnet. The adsorption results indicate that the obtained imprinted polymers have fast kinetics, an ultrahigh adsorption capacity of 479.9 mg g(-1), and satisfactory selectivity towards the template molecule. The prepared materials have excellent stability with no obvious deterioration after six adsorption-regeneration cycles. In addition, a method for determination of gallic acid (GA) in pomegranate rind was developed, using a combination of the prepared polymers used as solid-phase extraction (SPE) sorbents and high-performance liquid chromatography (HPLC) for rapid isolation and determination of GA. The limit of detection of the proposed method is 0.001 μg mL(-1), and the intra and inter-day relative standard deviations (RSDs) are lower than 3.8% and 5.3%, respectively. The recoveries of GA from pomegranate rind extract are in the range 98.2-103.6% with RSDs lower than 4.3%.

  12. Influence of polymer molecular weight and concentration on coexistence curve of isobutyric acid + water.

    PubMed

    Reddy, P Madhusudhana; Venkatesu, P; Bohidar, H B

    2011-10-27

    We report the influence of variation of molecular weights (MWs = 2, 4, 6, and 9 × 10(5) g mol(-1)) and concentration (C) of a long-chain polymer (polyethylene oxide, PEO) on an upper critical solution temperature (UCST) of isobutyric acid (I) + water (W) using density (ρ) measurements as a function of temperature. The ρ values in each coexisting phase of IW have been measured at three different PEO concentrations (C = 0.395, 0.796, and 1.605 mg/cm(3)) in the near critical composition of IW at temperatures below the system's upper critical point for each molecular weight (MW) of PEO. Further, to ascertain the PEO behavior in IW we have measured the polydispersity values for both coexisting liquid phases by using dynamic light scattering (DLS). The data show that the polymer was significantly affected in the critical region of IW and these various MWs and concentrations of PEO show significant modulation on the critical exponents (β), the critical temperatures (T(c)), and critical composition (ϕ(c)), which are depicting the shape of the coexistence curve. The values of β and T(c) increase with increasing PEO MW and concentrations. Besides, the ϕ(c) values slightly decrease with increasing the C values in the mixture of IW. However, the rate of decrease in ϕ(c) is insignificant. Our experimental results explicitly elucidate that most of polymer chain entangles in water rich phase, thereby the polymer monomers strongly interact with neighbor solvent particles and also intra chain interaction between polymer monomers.

  13. Electrochemical Coupling of Biomass-Derived Acids: New C8 Platforms for Renewable Polymers and Fuels.

    PubMed

    Wu, Linglin; Mascal, Mark; Farmer, Thomas J; Arnaud, Sacha Pérocheau; Wong Chang, Maria-Angelica

    2017-01-10

    Electrolysis of biomass-derived carbonyl compounds is an alternative to condensation chemistry for supplying products with chain length >C6 for biofuels and renewable materials production. Kolbe coupling of biomass-derived levulinic acid is used to obtain 2,7-octanedione, a new platform molecule only two low process-intensity steps removed from raw biomass. Hydrogenation to 2,7-octanediol provides a chiral secondary diol largely unknown to polymer chemistry, whereas intramolecular aldol condensation followed by hydrogenation yields branched cycloalkanes suitable for use as high-octane, cellulosic gasoline. Analogous electrolysis of an itaconic acid-derived methylsuccinic monoester yields a chiral 2,5-dimethyladipic acid diester, another underutilized monomer owing to lack of availability.

  14. Functionalization of Biodegradable PLA Nonwoven Fabric as Superoleophilic and Superhydrophobic Material for Efficient Oil Absorption and Oil/Water Separation.

    PubMed

    Gu, Jincui; Xiao, Peng; Chen, Peng; Zhang, Lei; Wang, Hanlin; Dai, Liwei; Song, Liping; Huang, Youju; Zhang, Jiawei; Chen, Tao

    2017-02-22

    Although the construction of superwettability materials for oil/water separation has been developed rapidly, the postprocess of the used separation materials themselves is still a thorny problem due to their nondegradation in the natural environment. In this work, we reported the functionalization of polylactic acid (PLA) nonwoven fabric as superoleophilic and superhydrophobic material for efficient treatment of oily wastewater with eco-friendly post-treatment due to the well-known biodegradable nature of PLA matrix.

  15. A Comparative Study on the Mechanical, Thermal and Morphological Characterization of Poly(lactic acid)/Epoxidized Palm Oil Blend

    PubMed Central

    Giita Silverajah, V. S.; Ibrahim, Nor Azowa; Yunus, Wan Md Zin Wan; Hassan, Hazimah Abu; Woei, Chieng Buong

    2012-01-01

    In this work, poly(lactic acid) (PLA) a fully biodegradable thermoplastic polymer matrix was melt blended with three different epoxidized palm oil (EPO). The aim of this research was to enhance the flexibility, mechanical and thermal properties of PLA. The blends were prepared at various EPO contents of 1, 2, 3, 4 and 5 wt% and characterized. The SEM analysis evidenced successful modification on the neat PLA brittle morphology. Tensile tests indicate that the addition of 1 wt% EPO is sufficient to improve the strength and flexibility compared to neat PLA. Additionally, the flexural and impact properties were also enhanced. Further, DSC analysis showed that the addition of EPO results in a decrease in Tg, which implies an increase in the PLA chain mobility. In the presence of 1 wt% EPO, TGA results revealed significant increase in the thermal stability by 27%. Among the three EPOs used, EPO(3) showed the best mechanical and thermal properties compared to the other EPO’s, with an optimum loading of 1 wt%. Conclusively, EPO showed a promising outcome to overcome the brittleness and improve the overall properties of neat PLA, thus can be considered as a potential plasticizer. PMID:22754338

  16. Crystallization and preliminary X-ray diffraction studies of BmooPLA2-I, a platelet-aggregation inhibitor and hypotensive phospholipase A2 from Bothrops moojeni venom

    PubMed Central

    Salvador, Guilherme H. M.; Marchi-Salvador, Daniela P.; Silveira, Lucas B.; Soares, Andreimar M.; Fontes, Marcos R. M.

    2011-01-01

    Phospholipases A2 (PLA2s) are enzymes that cause the liberation of fatty acids and lysophospholipids by the hydrolysis of membrane phospholipids. In addition to their catalytic action, a wide variety of pharmacological activities have been described for snake-venom PLA2s. BmooPLA2-I is an acidic, nontoxic and catalytic PLA2 isolated from Bothrops moojeni snake venom which exhibits an inhibitory effect on platelet aggregation, an immediate decrease in blood pressure, inducing oedema at a low concentration, and an effective bactericidal effect. BmooPLA2-I has been crystallized and X-ray diffraction data have been collected to 1.6 Å resolution using a synchrotron-radiation source. The crystals belonged to space group C2221, with unit-cell parameters a = 39.7, b = 53.2, c = 89.2 Å. The molecular-replacement solution of BmooPLA2-I indicated a monomeric conformation, which is in agreement with nondenaturing electrophoresis and dynamic light-scattering experiments. A comparative study of this enzyme with the acidic PLA2 from B. jararacussu (BthA-I) and other toxic and nontoxic PLA2s may provide important insights into the functional aspects of this class of proteins. PMID:21821890

  17. PLA 2010 Conference: Plenty for the Price

    ERIC Educational Resources Information Center

    Miller, Rebecca

    2010-01-01

    This article outlines Public Library Association (PLA) 2010 annual conference to be held in Oregon Convention Center, Portland on March 23-27. The days quickly fill up with the picks of over 100 programs as well as valuable "talk tables" and special events. The well-organized schedule, divided into eight broad tracks (e.g., technology,…

  18. Thermo-responsive behavior of borinic acid polymers: experimental and molecular dynamics studies.

    PubMed

    Wan, Wen-Ming; Zhou, Peng; Cheng, Fei; Sun, Xiao-Li; Lv, Xin-Hu; Li, Kang-Kang; Xu, Hai; Sun, Miao; Jäkle, Frieder

    2015-09-28

    The thermo-responsive properties of borinic acid polymers were investigated by experimental and molecular dynamics simulation studies. The homopolymer poly(styrylphenyl(tri-iso-propylphenyl)borinic acid) (PBA) exhibits an upper critical solution temperature (UCST) in polar organic solvents that is tunable over a wide temperature range by addition of small amounts of H2O. The UCST of a 1 mg mL(-1) PBA solution in DMSO can be adjusted from 20 to 100 °C by varying the H2O content from ∼0-2.5%, in DMF from 0 to 100 °C (∼3-17% H2O content), and in THF from 0 to 60 °C (∼4-19% H2O). The UCST increases almost linearly from the freezing point of the solvent with higher freezing point to the boiling point of the solvent with the lower boiling point. The mechanistic aspects of this process were investigated by molecular dynamics simulations. The latter indicate rapid and strong hydrogen-bond formation between BOH moieties and H2O molecules, which serve as crosslinkers to form an insoluble network. Our results suggest that borinic acid-containing polymers are promising as new "smart" materials, which display thermo-responsive properties that are tunable over a wide temperature range.

  19. Targeting hepatocellular carcinoma with aptamer-functionalized PLGA/PLA-PEG nanoparticles

    NASA Astrophysics Data System (ADS)

    Weigum, Shannon E.; Sutton, Melissa; Barnes, Eugenia; Miller, Sarah; Betancourt, Tania

    2014-08-01

    Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide, particularly in regions where chronic Hepatitis B and C infections are common. Nanoparticle assemblies that incorporate high-affinity aptamers which specifically bind malignant hepatocellular carcinoma cells could be useful for targeted drug delivery or enhancing contrast with existing ablation therapies. The in vitro interactions of a tumor-specific aptamer, TLS11a, were characterized in a hepatoma cell line via live-cell fluorescence imaging, SDS-PAGE and Western Blotting techniques. Cell surface binding of the aptamer-AlexaFluor®546 conjugate was found to occur within 20 minutes of initial exposure, followed by internalization and localization to late endosomes or lysosomes using a pH-sensitive LysoSensor™ Green dye and confocal microscopy. Aptamer-functionalized polymer nanoparticles containing poly(lactic-co-glycolic acid) (PLGA) and poly(lactide)-b-poly(ethylene glycol) (PLA-PEG) were then prepared by nanoprecipitation and passively loaded with the chemotherapeutic agent, doxorubicin, yielding spherical nanoparticles approximately 50 nm in diameter. Targeted drug delivery and cytotoxicity was assessed using live/dead fluorescent dyes and a MTT colorimetric viability assay with elevated levels of cell death found in cultures treated with either the aptamer-coated and uncoated polymer nanoparticles. Identification and characterization of the cell surface protein epitope(s) recognized by the TLS11a aptamer are ongoing along with nanoparticle optimization, but these preliminary studies support continued investigation of this aptamer and functionalized nanoparticle conjugates for targeted labeling and drug delivery within malignant hepatocellular carcinomas.

  20. The effect of the antioxidant on the properties of thiolated poly(aspartic acid) polymers in aqueous ocular formulations.

    PubMed

    Budai-Szűcs, Mária; Horvát, Gabriella; Gyarmati, Benjámin; Szilágyi, Barnabás Áron; Szilágyi, András; Berkó, Szilvia; Ambrus, Rita; Szabó-Révész, Piroska; Sandri, Giuseppina; Bonferoni, Maria Cristina; Caramella, Carla; Csányi, Erzsébet

    2017-04-01

    Thiolated polymers are a promising new group of excipients, but their stability against atmospheric oxidation has not been investigated in detail, and only a few efforts have been made to improve their stability. The oxidation of the thiol groups in solutions of thiolated polymers may result in a decrease of mucoadhesion and unpredictable in situ gelation. The aims of our work were to study the stability of aqueous solutions of thiolated polymers and the effects of stabilizing agents. We investigated thiolated poly(aspartic acid) polymers stabilized with dithiothreitol, glutathione or acetylcysteine. The effects of these antioxidants on the gel structure, mucoadhesion and drug release were determined by means of scanning electron microscopy, swelling, rheology, adhesion and drug release tests. It was concluded that the stability of polymer solutions containing antioxidants is sufficient for one day. Polymers stabilized with dithiotreitol demonstrated fast swelling and drug release, but weaker mucoadhesion as compared with the other samples. Polymers stabilized with glutathione displayed the weakest cohesive properties, resulting in fast and uncontrolled drug release and moderate mucoadhesion. Acetylcysteine-stabilized polymers exhibited an optimum cross-linked structure, with free thiol groups ensuring polymer-mucin interactions, resulting in the best mucoadhesive properties.

  1. Preparation and Determination of Drug-Polymer Interaction and In-vitro Release of Mefenamic Acid Microspheres Made of CelluloseAcetate Phthalate and/or Ethylcellulose Polymers

    PubMed Central

    Jelvehgari, Mitra; Hassanzadeh, Davoud; Kiafar, Farhad; Delf Loveym, Badir; Amiri, Sara

    2011-01-01

    The objective of this study was to formulate and evaluate the drug-polymer interaction of mefenamic acid (MA) using two polymers with different characteristics as ethylcellulose (EC) and/or cellulose acetate phthalate (CAP). Microspheres were prepared by the modified emulsion solvent evaporation (MESE). The effect of drug-polymer interaction was studied for each of microspheres. Important parameters in the evaluation of a microencapsulation technique are encapsulation efficiency, yield production, particle size, surface characteristics of microspheres, scanning electronic microscopy (SEM), powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC). The in-vitro release studies are performed in Tris buffer (pH 9) with Sodium lauryl sulfate (SLS). Microspheres containing CAP and EC showed 68-97% and 63-76% of entrapment efficiency, respectively. The thermogram X-ray and DSC showed stable character of MA in the microspheres and revealed an absence of drug polymer interaction. The prepared microspheres were spherical in shape and had a size range of 235-436 μm for CAP-microspheres and 358-442 μm for EC-microspheres. The results suggest that MA was successfully and efficiently encapsulated; the release rates of matrix microspheres are related to the type of polymer, only when polymers (EC and CAP combine with 1 : 1 ratio) were used to get prolonged drug release with reducing the polymers content in the microspheres. Data obtained from in-vitro release for microspheres and commercial capsule were fitted to various kinetic models and the high correlation was obtained in the peppas model. Mefenamic acid, Ethylcellulose, Cellulose acetate phthalate, Microparticles, Modified emulsion-solvent evaporation. PMID:24250377

  2. Thermal, mechanical and morphological characterization of plasticized PLA-PHB blends

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A blend of poly(lactic acid) (PLA) (75% by weight) and poly(3-hydroxybutyrate) (PHB) (25% by weight) with a polyester plasticizer (Lapol 108) at two different concentrations (5 and 7% by weight per 100 parts of the blends) were investigated by TGA, DSC, XRD, SEM, mechanical testing and biodegradatio...

  3. Fabrication of biodegradable PEG-PLA nanospheres for solubility, stabilization, and delivery of curcumin.

    PubMed

    Liang, Hongying; Friedman, Joel M; Nacharaju, Parimala

    2017-03-01

    Curcumin is an effective and safe anticancer agent, and also known to induce vasodilation, but its hydrophobicity limits its clinical application. In this study, a simple emulsion method was developed to prepare biodegradable poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) nanospheres to encapsulate curcumin to improve its solubility and stability. The nanoparticle size was around 150 nm with a narrow size distribution. Fluorescence microscopy showed that curcumin encapsulated PEG-PLA nanospheres were taken up rapidly by Hela and MDA-MB-231 cancer cells. This novel nanoparticulate carrier may improve the bioavailability of curcumin without affecting its anticancer properties.

  4. Development of novel multifunctional biobased polymer composites with tailored conductive network of micro-and-nano-fillers

    NASA Astrophysics Data System (ADS)

    Leung, Siu N.; Ghaffari, Shahriar; Naguib, Hani E.

    2013-04-01

    Biobased/green polymers and nanotechnology warrant a multidisciplinary approach to promote the development of the next generation of materials, products, and processes that are environmentally sustainable. The scientific challenge is to find the suitable applications, and thereby to create the demand for large scale production of biobased/green polymers that would foster sustainable development of these eco-friendly materials in contrast to their petroleum/fossil fuel derived counterparts. In this context, this research aims to investigate the synergistic effect of green materials and nanotechnology to develop a new family of multifunctional biobased polymer composites with promoted thermal conductivity. For instance, such composite can be used as a heat management material in the electronics industry. A series of parametric studies were conducted to elucidate the science behind materials behavior and their structure-toproperty relationships. Using biobased polymers (e.g., polylactic acid (PLA)) as the matrix, heat transfer networks were developed and structured by embedding hexagonal boron nitride (hBN) and graphene nanoplatelets (GNP) in the PLA matrix. The use of hybrid filler system, with optimized material formulation, was found to promote the composite's effective thermal conductivity by 10-folded over neat PLA. This was achieved by promoting the development of an interconnected thermally conductive network through structuring hybrid fillers. The thermally conductive composite is expected to afford unique opportunities to injection mold three-dimensional, net-shape, lightweight, and eco-friendly microelectronic enclosures with superior heat dissipation performance.

  5. 40 CFR 721.10594 - Hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydroxy...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid, 5... Specific Chemical Substances § 721.10594 Hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6... hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine,...

  6. 40 CFR 721.10594 - Hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydroxy...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid, 5... Specific Chemical Substances § 721.10594 Hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6... hexanedioic acid, polymer with 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine,...

  7. Fluorescence properties of a novel side-chain polymer based on polyamic acid

    NASA Astrophysics Data System (ADS)

    Lu, Jianmei; Yao, Shechun; Tang, Xiubo; Sun, Ming; Zhu, Xiulin

    2004-05-01

    The p-π conjugated polyamic acid (PAA) had been synthesized through 1,4-diaminoanthraquinone (DAAQ) and pyromellitic dianhydride (PMDA) under microwave irradiation. The graft PAAs were obtained by toluene-2,4-diisocyanate (TDI) derivatives having different straight-chain alkyl. The resulted graft polymers had good dissolution capabilities, film-forming capabilities and strong fluorescence. We investigated some factors influencing fluorescence performance on graft PAA and found that with increasing chain length of the straight-chain alkyl or increasing graft degree, the fluorescence intensity and quantum efficiency will be enhanced markedly.

  8. Influence of dehydrated nanotubed titanic acid on polymer light-emitting diodes with phosphorescent dye

    NASA Astrophysics Data System (ADS)

    Qian, L.; Zhang, T.; Wang, Y. S.; Xu, X. R.; Jin, Z. S.; Du, Z. L.

    2006-01-01

    In this letter, we demonstrate that hole injection and transport in polymer light-emitting diodes with phosphorescent dye Ir(ppy)3 can be significantly enhanced by doping p-type conductive dehydrated nanotubed titanic acid into poly(vinylcarbazole) (PVK) films at 2wt.%. At the same time, both energy transfer and exciton recombination efficiency are improved because of the open and straight conformation of the PVK molecule in the nanocomposite. The performance of these devices was greatly improved, showing higher luminance, enhanced efficiency, and a lower turn-on voltage.

  9. Preparation and characterization of electrospun alginate/PLA nanofibers as tissue engineering material by emulsion eletrospinning.

    PubMed

    Xu, Weihong; Shen, Renzhe; Yan, Yurong; Gao, Jie

    2017-01-01

    Scaffolds made by biomaterials offer favorite environment for cell grow and show a wide potential application in tissue engineering. Novel biocompatibility materials polylatic acid (PLA) nanofiber membranes with favorable biocompatibility and good mechanical strength could serve as an innovative tissue engineering scaffold. Sodium alginate (SA) could be used in biomedical areas because of its anti-bacterial property, hydrophilicity and biocompatibility. In this article, we chose PLA as continuous phase and SA as dispersion phase to prepare a W/O emulsion and then electrospun it to get a SA/PLA composite nanofiber membranes. The CLSM images illustrated that the existence of SA was located on the surface of composite fibers and the FTIR results confirmed the result. A calcium ion replacement step was used as an after-treatment for SA/PLA nanofiber membranes in order to anchor the alginic ion in a form of gelated calcium alginate (CA). The single fiber tensile test shows a good mechanical property of CA/PLA nanofiber membranes, and the nanofiber membranes are beneficial for cell proliferation and differentiation owing to MTT array as well as Alizarin red S (ARS) staining test.

  10. PlaMoM: a comprehensive database compiles plant mobile macromolecules

    PubMed Central

    Guan, Daogang; Yan, Bin; Thieme, Christoph; Hua, Jingmin; Zhu, Hailong; Boheler, Kenneth R.; Zhao, Zhongying; Kragler, Friedrich; Xia, Yiji; Zhang, Shoudong

    2017-01-01

    In plants, various phloem-mobile macromolecules including noncoding RNAs, mRNAs and proteins are suggested to act as important long-distance signals in regulating crucial physiological and morphological transition processes such as flowering, plant growth and stress responses. Given recent advances in high-throughput sequencing technologies, numerous mobile macromolecules have been identified in diverse plant species from different plant families. However, most of the identified mobile macromolecules are not annotated in current versions of species-specific databases and are only available as non-searchable datasheets. To facilitate study of the mobile signaling macromolecules, we compiled the PlaMoM (Plant Mobile Macromolecules) database, a resource that provides convenient and interactive search tools allowing users to retrieve, to analyze and also to predict mobile RNAs/proteins. Each entry in the PlaMoM contains detailed information such as nucleotide/amino acid sequences, ortholog partners, related experiments, gene functions and literature. For the model plant Arabidopsis thaliana, protein–protein interactions of mobile transcripts are presented as interactive molecular networks. Furthermore, PlaMoM provides a built-in tool to identify potential RNA mobility signals such as tRNA-like structures. The current version of PlaMoM compiles a total of 17 991 mobile macromolecules from 14 plant species/ecotypes from published data and literature. PlaMoM is available at http://www.systembioinfo.org/plamom/. PMID:27924044

  11. Engineered biosynthesis of biodegradable polymers.

    PubMed

    Jambunathan, Pooja; Zhang, Kechun

    2016-08-01

    Advances in science and technology have resulted in the rapid development of biobased plastics and the major drivers for this expansion are rising environmental concerns of plastic pollution and the depletion of fossil-fuels. This paper presents a broad view on the recent developments of three promising biobased plastics, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and polybutylene succinate (PBS), well known for their biodegradability. The article discusses the natural and recombinant host organisms used for fermentative production of monomers, alternative carbon feedstocks that have been used to lower production cost, different metabolic engineering strategies used to improve product titers, various fermentation technologies employed to increase productivities and finally, the different downstream processes used for recovery and purification of the monomers and polymers.

  12. Influence of lignin on morphology, structure and thermal behavior of polylactic acid-based biocomposites

    NASA Astrophysics Data System (ADS)

    Canetti, Maurizio; Cacciamani, Adriana; Bertini, Fabio

    2016-05-01

    Polylactic acid (PLA) is a thermoplastic biodegradable polymer that can be made from annually renewable resources. Lignin is a natural amorphous polyphenolic macromolecule inexpensive and easily available. In the present study PLA and acetylated lignin biocomposites were prepared by casting from chloroform solution. PLA can crystallize from the melt in the α and α' forms, depending on the adopted crystallization conditions. The presence of the lignin in the biocomposites can interfere with the crystal formation process. Isothermal crystallizations were performed at different temperatures, the presence of lignin causes an increase of the time of crystallization, while the overall crystallization rate and the spherulite radial growth rate decrease with enhancing the lignin content in the biocomposites.

  13. Preparation of polypyrrole-embedded electrospun poly(lactic acid) nanofibrous scaffolds for nerve tissue engineering

    PubMed Central

    Zhou, Jun-feng; Wang, Yi-guo; Cheng, Liang; Wu, Zhao; Sun, Xiao-dan; Peng, Jiang

    2016-01-01

    Polypyrrole (PPy) is a biocompatible polymer with good conductivity. Studies combining PPy with electrospinning have been reported; however, the associated decrease in PPy conductivity has not yet been resolved. We embedded PPy into poly(lactic acid) (PLA) nanofibers via electrospinning and fabricated a PLA/PPy nanofibrous scaffold containing 15% PPy with sustained conductivity and aligned topography. There was good biocompatibility between the scaffold and human umbilical cord mesenchymal stem cells as well as Schwann cells. Additionally, the direction of cell elongation on the scaffold was parallel to the direction of fibers. Our findings suggest that the aligned PLA/PPy nanofibrous scaffold is a promising biomaterial for peripheral nerve regeneration. PMID:27904497

  14. [Preparation of surface molecularly imprinted polymers for penicilloic acid, and its adsorption properties].

    PubMed

    Zheng, Penglei; Luo, Zhimin; Chang, Ruimiao; Ge, Yanhui; Du, Wei; Chang, Chun; Fu, Qiang

    2015-09-01

    On account of the specificity and reproducibility for the determination of penicilloic acid in penicillin, this study aims to prepare penicilloic acid imprinted polymers (PEOA-MIPs) by surface polymerization method at the surface of modified silica particles by using penicilloic acid (PEOA) as the template molecule, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate ( EGDMA) as the cross linker, and methanol/acetonitrile as the solvents. The synthesis conditions were optimized, and PEOA-MIPs had the best adsorption capacity when the molar ratio of template molecule/functional monomer was 1 :4, cross linking degree was 85% and the solvent ratio of methanol/acetonitrile was 1 :1 (v/v). The adsorption properties were evaluated by adsorption experiments, including the adsorption isotherms, kinetics and selectivity. The adsorption process between PEOA-MIPs and PEOA fitted the Langmuir adsorption isotherm with the maximum adsorption capacity of 122. 78 mg/g and the pseudo-second-order reaction kinetics with fast adsorption kinetics (the equilibrium time of 45 min). The as-synthesized PEOA-MIPs were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). The results indicated that the MIPs layer has been successfully grafted on the surface of SiO2 microparticles and the PEOA-MIPs had the excellent thermal stability. The PEOA-MIPs showed the highest selective recognition for PEOA. The PEOA-MIPs possess a high adsorption capacity, rapid mass-transfer rate and high selectivity to PEOA when compared with non-imprinted polymers (PEOA-NIPs). The PEOA-MIPs was expected to be used as the solid phase extraction medium and this study provides the potential applications for fast recognition and analysis of the penicilloic acid in penicillin.

  15. MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

    PubMed Central

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-01-01

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices. PMID:25365179

  16. MWCNTs-reinforced epoxidized linseed oil plasticized polylactic acid nanocomposite and its electroactive shape memory behaviour.

    PubMed

    Alam, Javed; Alam, Manawwer; Raja, Mohan; Abduljaleel, Zainularifeen; Dass, Lawrence Arockiasamy

    2014-10-31

    A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy "U"-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

  17. Sacrificial component fabrication for optimised production of micro-vascular polymer composite

    NASA Astrophysics Data System (ADS)

    Dalton, B.; Dixon, D.; McIlhagger, A.; Archer, E.

    2015-02-01

    Smart functional materials are a viable future goal for advanced applications in aerospace, space and medical applications. In this work micro-vascular polymer composite systems have been developed using sacrificial fibres produced from catalyst loaded Poly(lactic acid). The sacrificial fibres have been produced via a published technique which treated PLA in a solvent catalyst mixture of 60% Trifluoroethanol, 40% H2O dispersed with 10 wt% tin (II) oxalate catalyst. A second process of polymer extrusion of PLA using graded fill contents of tin (II) oxalate has also been developed for the up scaled production of fibres as an alternative to solution treatment. Thermal analysis (TGA) was used to compare sacrificial fibre specimens. PLA fibres produced via the polymer extrusion method outperformed solution treated fibres displaying a lower degradation onset temperature (average 25°C lower), higher degradation rates (observed through a derivative curve comparison) and lower residual catalyst content (0.67% solvent treated fibre against 0.16% extruded fibre). The continuous extrusion process is solvent free and is suitable for high volume production. This work has been carried out to fully understand the fabrication issues with sacrificial components.

  18. Potent inhibition of human immunodeficiency virus by MDL 101028, a novel sulphonic acid polymer.

    PubMed

    Taylor, D L; Brennan, T M; Bridges, C G; Mullins, M J; Tyms, A S; Jackson, R; Cardin, A D

    1995-10-01

    MDL 101028, a novel biphenyl disulphonic acid urea co-polymer was designed and synthesised as a heparin mimetic. This low molecular weight polymer showed potent inhibition of human immunodeficiency virus type 1 (HIV-1) replication in a number of host-cell/virus systems, including primary clinical isolates of the virus cultured in human peripheral blood mononuclear cells (PBMCs). When compared with the heterogeneous polysulphated molecules, heparin and dextran sulphate, this chemically defined compound showed equivalent antiviral activity with 50% inhibitory concentrations (IC50s) in the range 0.27-3.0 micrograms/ml in the host-cell/virus systems tested. MDL 101028 also inhibited the replication of HIV type 2 and the simian immunodeficiency virus (SIV), as well as HIV-1 variants resistant to reverse transcriptase inhibitors. Virus growth was blocked when exposure of T-lymphocytes to MDL 101028 was restricted to the virus absorption stage, or even in whole blood conditions. MDL 101028 did not irreversibly inactivate virions, and in contrast to heparin, did not inhibit the attachment of radiolabelled HIV-1 to CD4+ T-cells. MDL 101028 blocked HIV-induced cell-to-cell fusion and this activity appears to explain the mechanism of its antiviral action. The antiviral evaluation of discrete oligomer molecules of MDL 101028 showed that a polymer chain length of six repeating units had optimal potency. The lack of anticoagulant properties and significant antiviral activity in whole blood may allow the development of MDL 101028 as a treatment of HIV infections.

  19. Manipulating dispersion and distribution of graphene in PLA through novel interface engineering for improved conductive properties.

    PubMed

    Fu, Yu; Liu, Linshu; Zhang, Jinwen

    2014-08-27

    This study aimed to enhance the conductive properties of PLA nanocomposite by controlling the dispersion and distribution of graphene within the minor phase of the polymer blend. Functionalized graphene (f-GO) was achieved by reacting graphene oxide (GO) with various silanes under the aid of an ionic liquid. Ethylene/n-butyl acrylate/glycidyl methacrylate terpolymer elastomer (EBA-GMA) was introduced as the minor phase to tailor the interface of matrix/graphene through reactive compatibilization. GO particles were predominantly dispersed in PLA in a self-agglomerating pattern, while f-GO was preferentially located in the introduced rubber phase or at the PLA/EBA-GMA interfaces through the formation of the three-dimensional percolated structures, especially for these functionalized graphene with reactive groups. The selective localization of the f-GO also played a crucial role in stabilizing and improving the phase morphology of the PLA blend through reducing the interfacial tension between two phases. The establishment of the percolated network structures in the ternary system was responsible for the improved AC conductivity and better dielectric properties of the resulting nanocomposites.

  20. The influence of chemical surface modification of kenaf fiber using hydrogen peroxide on the mechanical properties of biodegradable kenaf fiber/poly(lactic acid) composites.

    PubMed

    Razak, Nur Inani Abdul; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Rayung, Marwah; Saad, Wan Zuhainis

    2014-03-07

    Bleaching treatment of kenaf fiber was performed in alkaline medium containing hydrogen peroxide solution maintained at pH 11 and 80 °C for 60 min. The bleached kenaf fiber was analyzed using Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) analysis. The bleached kenaf fiber was then compounded with poly-(lactic acid) (PLA) via a melt blending method. The mechanical (tensile, flexural and impact) performance of the product was tested. The fiber treatment improved the mechanical properties of PLA/bleached kenaf fiber composites. Scanning electron micrograph (SEM) morphological analysis showed improvement of the interfacial adhesion between the fiber surface and polymer matrix.

  1. Fabrication of a deoxyribonucleic acid polymer ridge waveguide electro-optic modulator by nanoimprint lithography

    NASA Astrophysics Data System (ADS)

    Fehrman Cory, Emily Marie

    The purpose of this dissertation is to develop the nanoimprint lithography (NIL) technique for direct patterning of the deoxyribonucleic acid biopolymer DNA-CTMA. The Mach Zehnder modulator was chosen as the test device to demonstrate the NIL patterning technique for DNA-CTMA as well as the unique optical and electrical properties of the DNA-CTMA as a cladding material for poled electro-optic polymers. Towards this goal, a DNA-CTMA clad inverted ridge waveguide is demonstrated at 633 nm and 1550 nm, the structure of which is patterned directly in the DNA-CTMA cladding by NIL. Additionally, EO modulation is demonstrated in a slab waveguide structure with DNA-CTMA cladding and SEO110 EO polymer core. Marine-derived deoxyribonucleic acid biopolymer (DNA-CTMA) is a green, nontoxic, low cost optical polymer material derived from waste products of the salmon fishing industry. It exhibits low optical loss at 1550 nm, forms a thin flexible film, is compatible with existing poled polymer technologies, increases the poling efficiency when used as a low resistivity cladding layer, and is thermally stable to 200 oC. Due to chemical incompatibility with the photoresists and the associated solvents, NIL has been developed for patterning the DNA biopolymer cladding to form an inverted ridge waveguide for the basis of the Mach Zehnder modulator. While DNA-CTMA presents significant advantages over other commonly used cladding materials for the 1550 nm wavelength range, one of the commonly used bands for optical communications, the mechanical properties and environmental susceptibility of the material poses significant fabrication challenges. A study of the effects of optical and mechanical effects of environmental humidity exposure are presented for the DNA-CTMA and SEO110 polymers used in the inverted ridge waveguide. While the soft, flexible nature of the DNA-CTMA is desirable for certain applications, this presents a challenge in producing a clean polished window for optical

  2. Enantiomeric PLA-PEG block copolymers and their stereocomplex micelles used as rifampin delivery

    NASA Astrophysics Data System (ADS)

    Chen, Li; Xie, Zhigang; Hu, Junli; Chen, Xuesi; Jing, Xiabin

    2007-10-01

    A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA-PEG block copolymers as a drug delivery carrier was described. The particles were encapsulated by enantiomeric PLA-PEG stereocomplex to form nanoscale micelles different from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric poly( l-lactide)-poly(ethylene-glycol) (PLLA-PEG) and poly( D-lactide)-poly(ethylene-glycol) (PDLA-PEG) were synthesized by the ring-opening polymerization of l-lactide and d-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained by the self-assembly of the equimolar mixtures of enantiomeric PLA-PEG copolymers in water. These micelles possessed partially the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8-4.8 mg/l and the mean hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block PLA content in the copolymer. Compared with the single PLLA-PEG or PDLA-PEG micelles, the cmc values of the stereocomplex micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated with rifampin were tested for the controlled release application. The rifampin loading capacity and encapsulation efficiency by the stereocomplex micelles were higher than those by the single polymer micelles, respectively. The drug release time in vitro was depending on the composites of the block copolymers and also could be controlled by the polymer molecular weight and the morphology of the polymer micelles.

  3. Porous Silicon and Polymer Nanocomposites for Delivery of Peptide Nucleic Acids as Anti-MicroRNA Therapies.

    PubMed

    Beavers, Kelsey R; Werfel, Thomas A; Shen, Tianwei; Kavanaugh, Taylor E; Kilchrist, Kameron V; Mares, Jeremy W; Fain, Joshua S; Wiese, Carrie B; Vickers, Kasey C; Weiss, Sharon M; Duvall, Craig L

    2016-09-01

    Self-assembled polymer/porous silicon nanocomposites overcome intracellular and systemic barriers for in vivo application of peptide nucleic acid (PNA) anti-microRNA therapeutics. Porous silicon (PSi) is leveraged as a biodegradable scaffold with high drug-cargo-loading capacity. Functionalization with a diblock polymer improves PSi nanoparticle colloidal stability, in vivo pharmacokinetics, and intracellular bioavailability through endosomal escape, enabling PNA to inhibit miR-122 in vivo.

  4. Novel Salted Anionic-Cationic Polymethacrylate Polymer Blends for Sustained Release of Acidic And Basic Drugs.

    PubMed

    Obeidat, Wasfy M; Qasim, Duaa; Nokhodchi, Ali; Al-Jabery, Ahmad; Sallam, Al-Sayed

    2016-05-02

    Since a unique matrix tablet formulation that independently controls the release of various drug types is in a great demand, the objective of this research was to develop a sustained release matrix tablet as a universal dosage form using a binary mixture of the salt forms of Eudragit polymers rather than their interpolyelectrolyte complexes. Tablets were prepared by wet granulation and compressed at different compression forces, depending on drug type. Dissolution tests were conducted using USP XXII rotating paddle apparatus at 50 rpm at 37°C in consecutive pH stages. Tablets containing Ibuprofen (IB) as a model acidic drug and Metronidazole (MD) as a model basic drug showed controlled/sustained release behavior. For IB tablets containing 80% Ibuprofen and 5% (w/w) polymeric combination; the time for 50% of the drug release was about 24 hours compared to 8.5 hours for plain tablets containing 80% IB. In case of MD, the drug release extended to about 7 hours for tablets containing 80% MD and 5% (w/w) polymeric combination, compared to about 1 hour for plain tablets containing 80% MD. In terms of extending the release of medications, the dissolution profiles of the tablets containing polymeric salts forms were found to be statistically superior to tablets prepared by direct compression of the polymers in their powdered base forms, and superior to tablets containing the same polymers granulated using isopropyl alcohol. The findings indicated the significance of combining the polymers in their salt forms in controlling the release of various drug types from matrices.

  5. Protein polymer conjugates: improving the stability of hemoglobin with poly(acrylic acid).

    PubMed

    Thilakarathne, Vindya; Briand, Victoria A; Zhou, Yuxiang; Kasi, Rajeswari M; Kumar, Challa V

    2011-06-21

    The synthesis, characterization, and evaluation of a novel polymer-protein conjugate are reported here. The covalent conjugation of high-molecular weight poly(acrylic acid) (PAA) to the lysine amino groups of met-hemoglobin (Hb) resulted in the covalent conjugation of Hb to PAA (Hb-PAA conjugate), as confirmed by dialysis and electrophoresis studies. The retention of native-like structure of Hb in Hb-PAA was established from Soret absorption, circular dichroism studies, and the redox activity of the iron center in Hb-PAA. The peroxidase-like activities of the Hb-PAA conjugate further confirmed the retention of Hb structure and biological activity. Thermal denaturation of the conjugate was investigated by differential scanning calorimetry and steam sterilization studies. The Hb-PAA conjugate indicated an improved denaturation temperature (T(d)) when compared to that of the unmodified Hb. One astonishing observation was that polymer conjugation significantly enhanced the Hb-PAA storage stability at room temperature. After 120 h of storage at room temperature in phosphate-buffered saline (PBS) at pH 7.4, for example, Hb-PAA retained 90% of its initial activity and unmodified Hb retained <60% of its original activity under identical conditions of buffer, pH, and temperature. Our conjugate demonstrates the key role of polymers in enhancing Hb stability via a very simple, efficient, general route. Water-swollen, lightly cross-linked, stable Hb-polymer nanogels of 100-200 nm were produced quickly and economically by this approach for a wide variety of applications.

  6. Toxicity test of biodegradable polymers by implantation in rabbit cornea.

    PubMed

    Kobayashi, H; Shiraki, K; Ikada, Y

    1992-11-01

    To evaluate whether or not the corneal micropocket implantation is effective for determining the toxicity of polymeric materials, currently used biodegradable polymers such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), LA-GA copolymers, and three kinds of poly(2-cyano-acrylate)s (PCA) were implanted in a rabbit corneal pouch and the tissue responses were observed macroscopically and microscopically. It was found that PLA induced no vascularization, whereas a residual solvent and ethylene oxide gas remaining in the PLA matrix invoked vascularization. Vascularization clearly took place when PGA was implanted in the cornea, which became opaque, probably because of cellular infiltration. In the case of PCA implantation, severe inflammation as well as vascular invasion occurred in the initial stage. It is likely that these tissue reactions were caused by the leachables from the implanted materials, the extent being dependent on the leaching rate and the toxicity. It was concluded that the corneal micropocket assay is a good means to detect trace amounts of leachables from implanted materials without sacrificing the animals with the implanted materials.

  7. Active food packaging based on molecularly imprinted polymers: study of the release kinetics of ferulic acid.

    PubMed

    Otero-Pazos, Pablo; Rodríguez-Bernaldo de Quirós, Ana; Sendón, Raquel; Benito-Peña, Elena; González-Vallejo, Victoria; Moreno-Bondi, M Cruz; Angulo, Immaculada; Paseiro-Losada, Perfecto

    2014-11-19

    A novel active packaging based on molecularly imprinted polymer (MIP) was developed for the controlled release of ferulic acid. The release kinetics of ferulic acid from the active system to food simulants (10, 20, and 50% ethanol (v/v), 3% acetic acid (w/v), and vegetable oil), substitutes (95% ethanol (v/v) and isooctane), and real food samples at different temperatures were studied. The key parameters of the diffusion process were calculated by using a mathematical modeling based on Fick's second law. The ferulic acid release was affected by the temperature as well as the percentage of ethanol of the simulant. The fastest release occurred in 95% ethanol (v/v) at 20 °C. The diffusion coefficients (D) obtained ranged between 1.8 × 10(-11) and 4.2 × 10(-9) cm(2)/s. A very good correlation between experimental and estimated data was obtained, and consequently the model could be used to predict the release of ferulic acid into food simulants and real food samples.

  8. Expedited Phonon Transfer in Interfacially Constrained Polymer Chain along Self-Organized Amino Acid Crystals.

    PubMed

    Mu, Liwen; Li, Yifan; Mehra, Nitin; Ji, Tuo; Zhu, Jiahua

    2017-04-05

    In this work, poly(vinyl alcohol) (PVA)/amino acid (AA) composites were prepared by a self-organized crystallization process. Five different AAs (cysteine, aspartic acid, glutamic acid, ornithine, and lysine) were selected based on their similar functional groups but different molecular structures. The different PVA-AA interactions in the five PVA/AA composites lead to two crystal patterns, i.e., continuous network (cysteine and lysine) and discrete particles (glutamic acid, ornithine, and aspartic acid). Scanning thermal microscopy is then applied to map the distribution of thermal conduction in these composites. It is found that the interface surrounding the crystals plays a dominating role in phonon transport where the polymer chains are greatly restrained by the interfacial confinement effect. Continuous crystal network builds up a continuous interface that facilitates phonon transfer while phonon scattering occurs in discrete crystalline structures. Significantly improved thermal conductivity of ∼0.7 W/m·K is observed in PVA/cysteine composite with AA loading of 8.4 wt %, which corresponds to a 170% enhancement as compared to pure PVA. The strong PVA-AA molecular interaction and self-organized crystal structure are considered the major reasons for the unique interface property and superior thermal conductivity.

  9. Polymer production by Klebsiella pneumoniae 4-hydroxyphenylacetic acid hydroxylase genes cloned in Escherichia coli.

    PubMed Central

    Gibello, A; Ferrer, E; Sanz, J; Martin, M

    1995-01-01

    The expression of Klebsiella pneumoniae hpaA and hpaH genes, which code for 4-hydroxyphenylacetic acid hydroxylase in Escherichia coli K-12 derivative strains, is associated with the production of a dark brown pigment in the cultures. This pigment has been identified as a polymer which shows several of the characteristics reported for microbial melanins and results from the oxidative activity of 4-hydroxyphenylacetic acid hydroxylase on some dihydroxylated compounds to form o-quinones. A dibenzoquinone is formed from the oxidation of different mono- or dihydroxylated aromatic compounds by the enzyme prior to polymerization. We report a hydroxylase activity, other than tyrosinase, that is associated with the synthesis of a bacterial melanin. PMID:8534083

  10. Electrochemical Coupling of Biomass‐Derived Acids: New C8 Platforms for Renewable Polymers and Fuels

    PubMed Central

    Wu, Linglin; Farmer, Thomas J.; Arnaud, Sacha Pérocheau; Wong Chang, Maria‐Angelica

    2016-01-01

    Abstract Electrolysis of biomass‐derived carbonyl compounds is an alternative to condensation chemistry for supplying products with chain length >C6 for biofuels and renewable materials production. Kolbe coupling of biomass‐derived levulinic acid is used to obtain 2,7‐octanedione, a new platform molecule only two low process‐intensity steps removed from raw biomass. Hydrogenation to 2,7‐octanediol provides a chiral secondary diol largely unknown to polymer chemistry, whereas intramolecular aldol condensation followed by hydrogenation yields branched cycloalkanes suitable for use as high‐octane, cellulosic gasoline. Analogous electrolysis of an itaconic acid‐derived methylsuccinic monoester yields a chiral 2,5‐dimethyladipic acid diester, another underutilized monomer owing to lack of availability. PMID:27873475

  11. ABS polymer electroless plating through a one-step poly(acrylic acid) covalent grafting.

    PubMed

    Garcia, Alexandre; Berthelot, Thomas; Viel, Pascal; Mesnage, Alice; Jégou, Pascale; Nekelson, Fabien; Roussel, Sébastien; Palacin, Serge

    2010-04-01

    A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate.

  12. Metal arsonate polymers of Cd, Zn, Ag and Pb supported by 4-aminophenylarsonic acid

    NASA Astrophysics Data System (ADS)

    Lesikar-Parrish, Leslie A.; Neilson, Robert H.; Richards, Anne F.

    2013-02-01

    The coordination preferences of 4-aminophenylarsonic acid, 4-NH2C6H4AsO3H2, (p-arsanilic acid) with CdCl2·2.5H2O, ZnCl2, Ag(SO3CF3) and Pb(NO3)2 have been investigated affording five new metal arsonate polymers. The reaction between 4-aminophenylarsonic acid and CdCl2·2.5H2O resulted in a one-dimensional polymer, [{Cd(4-NH3C6H4AsO3H)(Cl)2}(H2O)2]n, 1, in which the polymeric chain is propagated by bridging chlorides. Exchange of CdCl2 for ZnCl2 afforded [{Zn2(4-NH3C6H4AsO3)(Cl)2}(H2O)2(Cl)]n, 2, featuring interlinked 6- and 8-membered [Zn-O-As] ring systems. The reaction of Ag(SO3CF3) with 4-aminophenylarsonic acid, afforded polymeric 3, [Ag(4-NH2C6H4AsO3H)(4-NH2C6H4AsO3H2)]n where coordination of the amino group to the silver center is observed and [{Ag2(4-NH3C6H4AsO3H)(4-NH3C6H4AsO3)(μ2-SO3CF3)2}(SO3CF3)2]n, 4. By comparison, the reaction of p-arsanilic acid with Pb(NO3)2 yielded a polymeric chain [Pb(4-NH3C6H4AsO3H)(NO3)2]n, 5 of similar topology to 1. The structures of 1-5 have been indiscriminately characterized by single crystal X-ray diffraction and their composition supported by relevant spectroscopic techniques. A comparison of the structural features of these polymers is used to determine the coordination preference of the ligand and factors influencing structural motifs, for example, the role of the anion.

  13. PLA-grafting of collagen chains leading to a biomaterial with mechanical performances useful in tendon regeneration.

    PubMed

    Bellini, Davide; Cencetti, Claudia; Sacchetta, Anna Cristina; Battista, Angela Maria; Martinelli, Andrea; Mazzucco, Laura; Scotto D'Abusco, Anna; Matricardi, Pietro

    2016-12-01

    With the aim to obtain a scaffold with improved mechanical properties with respect to collagen for tendon augmentation and regeneration, a novel collagen-based material was prepared via heterogeneous phase derivatization of type I collagen sponges using polylactic acid. Compared to the untreated collagen, the functionalized sponge (Coll-PLA) was characterized by higher tensile properties and lower swelling capability; the degradation rate of Coll-PLA, in the presence of collagenase, was lower than that of the untreated collagen sponge. These results are related to an increased hydrophobic character of the collagen matrix due to the presence of PLA chains. In vitro tests, performed with human primary fibroblasts, showed that cell adhesion and proliferation rate on Coll-PLA were comparable to those obtained with the non-functionalized collagen. These findings suggest that the new biomaterial could be suitable as scaffold in tendon augmentation and regeneration.

  14. Evaluation of Influence of Various Polymers on Dissolution and Phase Behavior of Carbamazepine-Succinic Acid Cocrystal in Matrix Tablets.

    PubMed

    Ullah, Majeed; Ullah, Hanif; Murtaza, Ghulam; Mahmood, Qaisar; Hussain, Izhar

    2015-01-01

    The aim of current study was to explore the influence of three commonly used polymers, that is, cellulosics and noncellulosics, for example, Methocel K4M, Kollidon VA/64, and Soluplus, on the phase disproportionation and drug release profile of carbamazepine-succinic acid (CBZ-SUC) cocrystal at varying drug to polymer ratios (1 : 1 to 1 : 0.25) in matrix tablets. The polymorphic phase disproportionation during in-depth dissolution studies of CBZ-SUC cocrystals and its crystalline properties were scrutinized by X-ray powder diffractrometry and Raman spectroscopy. The percent drug release from HPMC formulations (CSH) showed inverse relation with the concentration of polymer; that is, drug release increased with decrease in polymer concentration. On contrary, direct relation was observed between percent drug release and polymer concentrations of Kollidon VA 64/Soluplus (CSK, CSS). At similar polymer concentration, drug release from pure carbamazepine was slightly lower with HPMC formulations than that of cocrystal; however, opposite trend in release rate was observed with Kollidon VA/64 and Soluplus. The significant increase in dissolution rate of cocrystal occurred with Kollidon VA/64 and Soluplus at higher polymer concentration. Moreover, no phase change took place in Methocel and Kollidon formulations. No tablet residue was left for Soluplus formulation so the impact of polymer on cocrystal integrity cannot be predicted.

  15. Small-angle neutron scattering by the tungsten and molybdenum oxides synthesized from polymer-salt complexes in acidic medium

    NASA Astrophysics Data System (ADS)

    Bogdanov, S.; Valiev, E.; Pirogov, A.; Teplykh, A.; Ostroushko, A.

    2004-07-01

    The peculiarities of oxide phase formation processes under the pyrolysis of salt and polymer-salt compounds based on polyvinyl alcohol and molybdenum and tungsten salts acidified by nitric acid have been studied. For that samples were prepared by annealing in a temperature range of 100-600°C and investigated by small-angle neutron scattering and X-ray diffraction methods. Similar samples with no polymer in their composition were studied for comparison. A size distribution of oxide phase particles, a specific surface area, a volume fraction and a mean particle size were found to be dependent on an annealing temperature and availability of the polymer. The characteristics of the above samples were compared with those of the earlier samples synthesized from solutions with a naturally established acidity. A mechanism of oxide particle formation under a thermal decomposition of the acidic compounds is provided.

  16. A PLA1-2 Punch Regulates the Golgi Complex

    PubMed Central

    Bechler, Marie E.; de Figueiredo, Paul; Brown, William J.

    2011-01-01

    The mammalian Golgi complex, trans Golgi network (TGN) and ER-Golgi-Intermediate Compartment (ERGIC) are comprised of membrane cisternae, coated vesicles and membrane tubules, all of which contribute to membrane trafficking and maintenance of their unique architectures. Recently, a new cast of players was discovered to regulate the Golgi and ERGIC: four unrelated cytoplasmic phospholipase A (PLA) enzymes, cPLA2α (GIVA cPLA2), PAFAH Ib (GVIII PLA2), iPLA2-β (GVIA-2 iPLA2), and iPLA1γ. These ubiquitously expressed enzymes regulate membrane trafficking from specific Golgi subcompartments, although there is evidence for some functional redundancy between PAFAH Ib and cPLA2α. Three of these enzymes, PAFAH Ib, cPLA2α, and iPLA2-β, exert effects on Golgi structure and function by inducing the formation of membrane tubules. Here, we review our current understanding of how PLA enzymes regulate Golgi and ERGIC morphology and function. PMID:22130221

  17. Direct sensing of total acidity by chronopotentiometric flash titrations at polymer membrane ion-selective electrodes.

    PubMed

    Gemene, Kebede L; Bakker, Eric

    2008-05-15

    Polymer membrane ion-selective electrodes containing lipophilic ionophores are traditionally interrogated by zero current potentiometry, which, ideally, gives information on the sample activity of ionic species. It is shown here that a discrete cathodic current pulse across an H (+)-selective polymeric membrane doped with the ionophore ETH 5294 may be used for the chronopotentiometric detection of pH in well-buffered samples. However, a reduction in the buffer capacity leads to large deviations from the expected Nernstian response slope. This is explained by the local depletion of hydrogen ions at the sample-membrane interface as a result of the galvanostatically imposed ion flux in direction of the membrane. This depletion is found to be a function of the total acidity of the sample and can be directly monitored chronopotentiometrically in a flash titration experiment. The subsequent application of a baseline potential pulse reverses the extraction process of the current pulse, allowing one to interrogate the sample with minimal perturbation. In one protocol, total acidity is found to be proportional to the magnitude of applied current at the flash titration end point. More conveniently, the square root of the flash titration end point time observed at a fixed applied current is a linear function of the total acid concentration. This suggests that it is possible to perform rapid localized pH titrations at ion-selective electrodes without the need for volumetric titrimetry. The technique is explored here for acetic acid, MES and citric acid with promising results. Polymeric membrane electrodes based on poly(vinyl chloride) plasticized with o-nitrophenyl octyl ether in a 1:2 mass ratio may be used for the detection of acids of up to ca. 1 mM concentration, with flash titration times on the order of a few seconds. Possible limitations of the technique are discussed, including variations of the acid diffusion coefficients and influence of electrical migration.

  18. Cytocompatibility of novel extracellular matrix protein analogs of biodegradable polyester polymers derived from α-hydroxy amino acids.

    PubMed

    Lecht, Shimon; Cohen-Arazi, Naomi; Cohen, Gadi; Ettinger, Keren; Momic, Tatjana; Kolitz, Michal; Naamneh, Majdi; Katzhendler, Jehoshua; Domb, Abraham J; Lazarovici, Philip; Lelkes, Peter I

    2014-01-01

    One of the challenges in regenerative medicine is the development of novel biodegradable materials to build scaffolds that will support multiple cell types for tissue engineering. Here we describe the preparation, characterization, and cytocompatibility of homo- and hetero-polyesters of α-hydroxy amino acid derivatives with or without lactic acid conjugation. The polymers were prepared by a direct condensation method and characterized using gel permeation chromatography, (1)H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, optical activity, and solubility. The surface charge of the polymers was evaluated using zeta potential measurements. The polymers were coated onto glass cover slips followed by characterization using nano-surface profiler, thin film reflectometry, and atomic force microscopy (AFM). Their interaction with endothelial and neuronal cells was assessed using adhesion, proliferation, and differentiation assays. Of the characterized polymers, Poly-HOVal-LA, but not Poly-(D)HOPhe, significantly augmented nerve growth factor (NGF)-induced neuronal differentiation of the PC12 pheochromcytoma cells. In contrast, Poly-HOLeu increased by 20% the adhesion of endothelial cells, but did not affect PC12 cell differentiation. NGF-induced Erk1/2 phosphorylation in PC12 cells grown on the different polymers was similar to the effect observed for cells cultured on collagen type I. While no significant association could be established between charge and the differentiative/proliferative properties of the polymers, AFM analysis indicated augmentation of NGF-induced neuronal differentiation on smooth polymer surfaces. We conclude that overall selective cytocompatibility and bioactivity might render α-hydroxy amino acid polymers useful as extracellular matrix-mimicking materials for tissue engineering.

  19. Self-assembly thermodynamics of pH-responsive amino-acid-based polymers with a nonionic surfactant.

    PubMed

    Bogomolova, Anna; Keller, Sandro; Klingler, Johannes; Sedlak, Marian; Rak, Dmytro; Sturcova, Adriana; Hruby, Martin; Stepanek, Petr; Filippov, Sergey K

    2014-09-30

    The behavior of pH-responsive polymers poly(N-methacryloyl-l-valine) (P1), poly(N-methacryloyl-l-phenylalanine) (P2), and poly(N-methacryloylglycyne-l-leucine) (P3) has been studied in the presence of the nonionic surfactant Brij98. The pure polymers phase-separate in an acidic medium with critical pHtr values of 3.7, 5.5, and 3.4, respectively. The addition of the surfactant prevents phase separation and promotes reorganization of polymer molecules. The nature of the interaction between polymer and surfactant depends on the amino acid structure in the side chain of the polymer. This effect was investigated by dynamic light scattering, isothermal titration calorimetry, electrophoretic measurements, small-angle neutron scattering, and infrared spectroscopy. Thermodynamic analysis revealed an endothermic association reaction in P1/Brij98 mixture, whereas a strong exothermic effect was observed for P2/Brij98 and P3/Brij98. Application of regular solution theory for the analysis of experimental enthalpograms indicated dominant hydrophobic interactions between P1 and Brij98 and specific interactions for the P2/Brij98 system. Electrophoretic and dynamic light scattering measurements support the applicability of the theory to these cases. The specific interactions can be ascribed to hydrogen bonds formed between the carboxylic groups of the polymer and the oligo(ethylene oxide) head groups of the surfactant. Thus, differences in polymer-surfactant interactions between P1 and P2 polymers result in different structures of polymer-surfactant complexes. Specifically, small-angle neutron scattering revealed pearl-necklace complexes and "core-shell" structures for P1/Brij98 and P2/Brij98 systems, respectively. These results may help in the design of new pH-responsive site-specific micellar drug delivery systems or pH-responsive membrane-disrupting agents.

  20. Nanostructured poly (lactic acid) electrospun fiber with high loadings of TiO2 nanoparticles: Insights into bactericidal activity and cell viability.

    PubMed

    Toniatto, T V; Rodrigues, B V M; Marsi, T C O; Ricci, R; Marciano, F R; Webster, T J; Lobo, A O

    2017-02-01

    Researchers have been looking for modifying surfaces of polymeric biomaterials approved by FDA to obtain nanofeatures and bactericidal properties. If modified, it would be very interesting because the antibiotic administration could be reduced and, therefore, the bacterial resistance. Here, we report the electrospinning of poly (lactic acid) (PLA) with high loadings of titanium dioxide nanoparticles (TiO2, 1-5wt%) and their bactericidal properties. TiO2 nanoparticles have been recognized for a long time for their antibacterial, low cost and self-cleaning properties. However, their ability to reduce bacteria functions when used in polymers has not been well studied to date. In this context, we aimed here to generate nanostructured PLA electrospun fiber-TiO2 nanoparticle composites for further evaluation of their bactericidal activity and cell viability. TEM and SEM micrographs revealed the successful electrospinning of PLA/TiO2 and the generation of polymer-TiO2 nanostructures. When increasing the TiO2 concentration, we observed a proportional increase in the nanoparticle density along the fiber and surface. The nanostructured PLA/TiO2 nanofibers showed no mammalian cell toxicity and, most importantly, possessed bactericidal activity with higher TiO2 loads. Such results suggest that the present PLA electrospun fiber-TiO2 nanoparticle composites should be further studied for a wide range of biomedical applications.

  1. PLA Reforms and Chinas Nuclear Forces

    DTIC Science & Technology

    2016-10-01

    will affect the force structure , adminis- tration, and command and control mechanisms of the People’s Liberation Army (PLA). The reforms have the...Army (PLAA) headquarters and the Strategic Support Force. Establishment of a separate headquarters will move the PLAA to a bureaucratic structure and...commands and the re- structured Central Military Commission (CMC), however, are staffed by PLAA officers, so the effectiveness of this change remains to

  2. Computational approach to the rational design of molecularly imprinted polymers for voltammetric sensing of homovanillic acid.

    PubMed

    Diñeiro, Yolanda; Menéndez, M Isabel; Blanco-López, M Carmen; Lobo-Castañón, M Jesús; Miranda-Ordieres, Arturo J; Tuñón-Blanco, Paulino

    2005-10-15

    A methodology based on density functional theory calculations for the design of molecularly imprinted polymers (MIPs) is described. The method allows the rational choice of the most suitable monomer and polymerization solvent among a set of chemicals traditionally used in MIP formulations for the molecular imprinting of a given template. It is based on the comparison of the stabilization energies of the prepolymerization adducts between the template and different functional monomers. The effect of the polymerization solvent is included using the polarizable continuum model. A voltammetric sensor for homovanillic acid was constructed using different MIPs as recognition element, confirming that the solvent (toluene) and functional monomer (methacrylic acid) selected according to the theoretical predictions lead to the most efficient molecular recognition sensing phase. With the voltammetric sensor prepared using the MIP designed according to the theoretical predictions, a linear response for concentrations of homovanillic acid between 5 x 10(-8) and 1 x 10(-5) M can be obtained. The limit of detection is 7 x 10(-9) M. The selectivity obtained for homovanillic acid over other structurally related compounds buttresses the validity of this strategy of design.

  3. Optimization of processing parameter for fabrication of polylactic acid/liquid natural rubber/graphene nanoplatelet by tensile properties

    NASA Astrophysics Data System (ADS)

    Shahdan, Dalila; Ahmad, Sahrim Hj.; Chen, Ruey Shan; Ali, Adilah Mat; Zailan, Farrah Diyana

    2016-11-01

    A study on processing parameter of polylactic acid (PLA) and graphene nanoplatelet (GNP) prepared via melt blending method using Haake Rheomix internal mixer. In this study liquid natural rubber (LNR) was used as compatibilizer and at the same time introducing ductile property into the nanocomposite blending. In order to determine the optimal processing parameter, nanocomposites were fabricated from PLA: LNR with ratio of 90:10, and 0.2 wt. % of graphene nanoplatelet with different mixing parameter condition; mixing temperature, rotor speed and mixing time. The optimal processing parameter was determined from the results of tensile testing. An optimum processing parameter of polymer nanocomposite was obtained at 180 °C of mixing temperature, 100 rpm of mixing speed and 14 min of mixing time. The SEM micrographs confirmed the dispersion of GNP in the PLA matrix.

  4. Production of degradable polymers from food-waste streams

    SciTech Connect

    Tsai, S.P.: Coleman, R.D.; Bonsignore, P.V.; Moon, S.H.

    1992-01-01

    In the United States, billions of pounds of cheese whey permeate and approximately 10 billion pounds of potatoes processed each year are typically discarded or sold as cattle feed at $3{endash}6/ton; moreover, the transportation required for these means of disposal can be expensive. As a potential solution to this economic and environmental problem, Argonne National Laboratory is developing technology that: Biologically converts existing food-processing waste streams into lactic acid and uses lactic acid for making environmentally safe, degradable polylactic acid (PLA) and modified PLA plastics and coatings. An Argonne process for biologically converting high-carbohydrate food waste will not only help to solve a waste problem for the food industry, but will also save energy and be economically attractive. Although the initial substrate for Argonne's process development is potato by-product, the process can be adapted to convert other food wastes, as well as corn starch, to lactic acid. Proprietary technology for biologically converting greater than 90% of the starch in potato wastes to glucose has been developed. Glucose and other products of starch hydrolysis are subsequently fermented by bacteria that produce lactic acid. The lactic acid is recovered, concentrated, and further purified to a polymer-grade product.

  5. Production of degradable polymers from food-waste streams

    SciTech Connect

    Tsai, S.P.: Coleman, R.D.; Bonsignore, P.V.; Moon, S.H.

    1992-07-01

    In the United States, billions of pounds of cheese whey permeate and approximately 10 billion pounds of potatoes processed each year are typically discarded or sold as cattle feed at $3{endash}6/ton; moreover, the transportation required for these means of disposal can be expensive. As a potential solution to this economic and environmental problem, Argonne National Laboratory is developing technology that: Biologically converts existing food-processing waste streams into lactic acid and uses lactic acid for making environmentally safe, degradable polylactic acid (PLA) and modified PLA plastics and coatings. An Argonne process for biologically converting high-carbohydrate food waste will not only help to solve a waste problem for the food industry, but will also save energy and be economically attractive. Although the initial substrate for Argonne`s process development is potato by-product, the process can be adapted to convert other food wastes, as well as corn starch, to lactic acid. Proprietary technology for biologically converting greater than 90% of the starch in potato wastes to glucose has been developed. Glucose and other products of starch hydrolysis are subsequently fermented by bacteria that produce lactic acid. The lactic acid is recovered, concentrated, and further purified to a polymer-grade product.

  6. A comparative in vitro evaluation of self-assembled PTX-PLA and PTX-MPEG-PLA nanoparticles

    NASA Astrophysics Data System (ADS)

    Cui, Fei; Li, Yang; Zhou, Shuifan; Jia, Mengmeng; Yang, Xiangrui; Yu, Fei; Ye, Shefang; Hou, Zhenqing; Xie, Liya

    2013-06-01

    We present a dialysis technique to direct the self-assembly of paclitaxel (PTX)-loaded nanoparticles (NPs) using methoxypolyethylene glycol-poly( d, l-lactide) (MPEG-PLA) and PLA, respectively. The composition, morphology, particle size and zeta potential, drug loading content, and drug encapsulation efficiency of both PTX-PLA NPs and PTX-MPEG-PLA NPs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, dynamic light scattering, electrophoretic light scattering, and high-performance liquid chromatography. The passive targeting effect and in vitro cell viability of the PTX-MPEG-PLA NPs on HeLa cells were demonstrated by comparative cellular uptake and MTT assay of the PTX-PLA NPs. The results showed that the PTX-MPEG-PLA NPs and PTX-PLA NPs presented a hydrodynamic particle size of 179.5 and 441.9 nm, with a polydispersity index of 0.172 and 0.189, a zeta potential of -24.3 and -42.0 mV, drug encapsulation efficiency of 18.3% and 20.0%, and drug-loaded content of 1.83% and 2.00%, respectively. The PTX-MPEG-PLA NPs presented faster release rate with minor initial burst compared to the PTX-PLA NPs. The PTX-MPEG-PLA NPs presented superior cell cytotoxicity and excellent cellular uptake compared to the PTX-PLA NPs. These results suggested that the PTX-MPEG-PLA NPs presented more desirable characteristics for sustained drug delivery compared to PTX-PLA NPs.

  7. In vitro release of theophylline from poly(lactic acid) sustained-release pellets prepared by direct compression.

    PubMed

    Kader, A; Jalil, R

    1998-06-01

    Poly(L-lactic acid), (L-PLA) pellets containing theophylline as a model drug were prepared with increasing bovine serum albumin (BSA) load of 10, 20, 30, 40, or 50% by direct compression. The drug release from pellets was studied in phosphate buffered saline (PBS, pH 7.4) at 37 degrees C. The annealing effect on theophylline release from pellets was also studied at 20, 30, 60, and 80 degrees C. In all cases, release kinetics followed the Higuchian mechanism with an initial burst effect followed by sustained release of theophylline during the experimental period. Increasing BSA load resulted in a linear increase in Higuchian release rates presumably because of the hydrophilic nature of BSA. Furthermore, BSA did not interact chemically with the polymer matrix and was held physically by the dense polymer matrix. However, drug release decreased with an increase in annealing temperature. Release of theophylline was higher from PLA-BSA combination pellets compared to PLA pellets at temperatures below the glass transition temperature (Tg) of the polymer and lower for temperatures above Tg. The temperature effect on drug release may be attributed to both the reduction of core solubility in the bulk phase and the lowering of diffusibility of the polymeric membrane. No drug-polymer interactions or polymer degradation was observed within the experimental setup when studied by differential scanning calorimetry (DSC), infrared (FTIR) spectroscopy, and gravimetric methods. DSC studies of pellets showed no hints of microstructural changes (crystallinity) of the polymers. In our experiments, theophylline was released primarily by leaching through channels and not by polymer degradation. The release rate was dependent on BSA loading and annealing. It may be concluded that PLA pellets can be fabricated suitably using BSA and annealing to design sustained-release preparations of water-soluble drugs.

  8. Poly(2-vinylnaphthalene-alt-maleic acid)-graft polystyrene as a photoactive polymer micelle and stabilizer for polystyrene latexes

    SciTech Connect

    Cao, T.; Yin, W.; Webber, S.E. )

    1994-12-05

    Polymerization of maleic anhydride and 2-vinylnaphthalene produces alternating polymers. Imidization of the polymer with amino-terminated polystyrene yields different loadings of an alternating polymer with polystyrene combs''. Upton rigorous hydrolysis one obtains poly(2-vinylnaphthalene-alt-maleic acid)-graft-polystyrene (P2VNMA-PS), which is a fluorescent polymer with unusual solution properties and with significant surface activity. P2VNMA-PS forms a small micelle structure in solution or can be used as a surfactant for an emulsion polymerization of polystyrene (no cosurfactant is required), producing monodisperse latex particles which are stable for pH > 3.9. Centrifugation shows that >90% of the P2VNMA-PS is associated with the latex particles. Fluorescence quenching studies of the naphthalene excimer with Tl[sup +] indicate that approximately 84% and 77% of the naphthalene groups remain exposed to the aqueous phase when this polymer is micellized or incorporated onto a latex particle, respectively. These data imply that the P2VNMA-PS polymer is permanently associated with the exterior of the latex particle, as one would expect given the amphiphilic nature of this polymer.

  9. Controlling Internal Organization of Multilayer Poly(methacrylic acid) Hydrogels with Polymer Molecular Weight

    DOE PAGES

    Kozlovskaya, Veronika; Zavgorodnya, Oleksandra; Ankner, John F.; ...

    2015-11-16

    Here, we report on tailoring the internal architecture of multilayer-derived poly(methacrylic acid) (PMAA) hydrogels by controlling the molecular weight of poly(N-vinylpyrrolidone) (PVPON) in hydrogen-bonded (PMAA/PVPON) layer-by-layer precursor films. The hydrogels are produced by cross-linking PMAA in the spin-assisted multilayers followed by PVPON release. We found that the thickness, morphology, and architecture of hydrogen-bonded films and the corresponding hydrogels are significantly affected by PVPON chain length. For all systems, an increase in PVPON molecular weight from Mw = 2.5 to 1300 kDa resulted in increased total film thickness. We also show that increasing polymer Mw smooths the hydrogen-bonded film surfaces butmore » roughens those of the hydrogels. Using deuterated dPMAA marker layers in neutron reflectometry measurements, we found that hydrogen-bonded films reveal a high degree of stratification which is preserved in the cross-linked films. We observed dPMAA to be distributed more widely in the hydrogen-bonded films prepared with small Mw PVPON due to the greater mobility of short-chain PVPON. Furthermore, these variations in the distribution of PMAA are erased after cross-linking, resulting in a distribution of dPMAA over about two bilayers for all Mw but being somewhat more widely distributed in the films templated with higher Mw PVPON. Finally, our results yield new insights into controlling the organization of nanostructured polymer networks using polymer molecular weight and open opportunities for fabrication of thin films with well-organized architecture and controllable function.« less

  10. Controlling Internal Organization of Multilayer Poly(methacrylic acid) Hydrogels with Polymer Molecular Weight

    SciTech Connect

    Kozlovskaya, Veronika; Zavgorodnya, Oleksandra; Ankner, John F.; Kharlampieva, Eugenia

    2015-11-16

    Here, we report on tailoring the internal architecture of multilayer-derived poly(methacrylic acid) (PMAA) hydrogels by controlling the molecular weight of poly(N-vinylpyrrolidone) (PVPON) in hydrogen-bonded (PMAA/PVPON) layer-by-layer precursor films. The hydrogels are produced by cross-linking PMAA in the spin-assisted multilayers followed by PVPON release. We found that the thickness, morphology, and architecture of hydrogen-bonded films and the corresponding hydrogels are significantly affected by PVPON chain length. For all systems, an increase in PVPON molecular weight from Mw = 2.5 to 1300 kDa resulted in increased total film thickness. We also show that increasing polymer Mw smooths the hydrogen-bonded film surfaces but roughens those of the hydrogels. Using deuterated dPMAA marker layers in neutron reflectometry measurements, we found that hydrogen-bonded films reveal a high degree of stratification which is preserved in the cross-linked films. We observed dPMAA to be distributed more widely in the hydrogen-bonded films prepared with small Mw PVPON due to the greater mobility of short-chain PVPON. Furthermore, these variations in the distribution of PMAA are erased after cross-linking, resulting in a distribution of dPMAA over about two bilayers for all Mw but being somewhat more widely distributed in the films templated with higher Mw PVPON. Finally, our results yield new insights into controlling the organization of nanostructured polymer networks using polymer molecular weight and open opportunities for fabrication of thin films with well-organized architecture and controllable function.

  11. Halochromic coordination polymers based on a triarylmethane dye for reversible detection of acids.

    PubMed

    Zavakhina, Marina S; Yushina, Irina V; Samsonenko, Denis G; Dybtsev, Danil N; Fedin, Vladimir P; Argent, Stephen P; Blake, Alexander J; Schröder, Martin

    2017-01-03

    Chromeazurol B (Na2HL) is a pH-sensitive (halochromic) dye based on a hydroxytriarylmethane core and two carboxylate functional groups, which makes it suitable for the synthesis of coordination polymers. Two new coordination polymers [NaZn4(H2O)3(L)3]·3THF·3H2O (1) and [Zn3(H2O)3(μ2-OH2)(μ3-OH)(HL)2(H2L)]·2THF·3H2O (2) incorporating Chromeazurol B linkers have been prepared and characterised. The structure of 1 comprises pentanuclear heterometallic {Zn4Na} nodes linked by six L(3-) anions to give a layered structure with a honeycomb topology. 2 crystallizes as a double-chain ribbon (ladder) structure with two types of metal node: a mononuclear Zn(ii) cation and tetranuclear {Zn(ii)}4 cluster. Chromeazurol B anions link each tetranuclear cluster to four individual Zn(ii) cations and each Zn(ii) cation with four tetranuclear clusters. Both compounds show pH-sensitivity in water solution which can be observed visually, giving the first example of a halochromic coordination polymer. The halochromic properties of 1 towards HCl vapors were systematically investigated. As-synthesized violet-grey 1 reversibly changes color from orange to pink in the presence of vapors of 2 M and 7 M HCl, respectively. The coordination of the Chromeazurol B anion at each color stage was examined by diffuse reflectance spectroscopy and FT-IR measurements. The remarkable stability of 1 to acid and the observed reversible and reproducible color changes provide a new design for multifunctional sensor materials.

  12. Theoretical and experimental research on the self-assembled system of molecularly imprinted polymers formed by salbutamol and methacrylic acid.

    PubMed

    Jun-Bo, Liu; Yang, Shi; Shan-Shan, Tang; Rui-Fa, Jin

    2015-03-01

    The quantum chemical method was applied for screening functional monomers in the rational design of salbutamol-imprinted polymers. Salbutamol was the template molecule, and methacrylic acid was the single functional monomer. The LC-WPBE/6-31G(d,p) method was used to investigate the geometry optimization, active sites, natural bond orbital charges, binding energies of the imprinted molecule, and solvation energy. The mechanism of action between salbutamol and methacrylic acid was also discussed. The theoretical results show that salbutamol interacts with functional monomers by hydrogen bonds, and the salbutamol-imprinted polymers with a ratio of 1:4 (salbutamol/methacrylic acid) in acetonitrile had the highest stability. The salbutamol-imprinted polymers were prepared by precipitation polymerization. The experimental results indicated that the maximum adsorption capacity for salbutamol toward molecularly imprinted polymers was 7.33 mg/g, and the molecularly imprinted polymers had a higher selectivity for salbutamol than for norepinephrine and terbutaline sulfate. Herein, the studies can provide theoretical and experimental references for the salbutamol molecular imprinted system.

  13. 40 CFR 721.10369 - Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with diphenyl P-methylphosphonate and 4,4â²-(1-methylethylidene) bis . 721.10369 Section 721.10369... Carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and 4,4′-(1-methylethylidene) bis... identified as carbonic acid, diphenyl ester, polymer with diphenyl P-methylphosphonate and...

  14. Impact of solvents and supercritical CO{sub 2} drying on the morphology and structure of polymer-based biofilms

    SciTech Connect

    Causa, Andrea; Acierno, Domenico; Filippone, Giovanni; Salerno, Aurelio; Domingo, Concepción

    2014-05-15

    In the present work, two-dimensional systems based on biodegradable polymers such as poly(ε-caprolactone) (PCL), poly(ethylene oxide) (PEO) and polylactic acid (PLA) are fabricated by means of a sustainable approach which consists in inducing phase separation in solutions of such polymers and “green” solvents, namely ethyl lactate (EL) and ethyl acetate (EA). The extraction of the solvent is promoted by a controlled drying process, which is performed in either air or supercritical CO{sub 2}. The latter can indeed act as both an antisolvent, which favors the deposition of the polymer by forming a mixture with EL and EA, and a plasticizing agent, whose solvation and transport properties may considerably affect the microstructure and crystallinity of the polymer films. The morphological, topographical and crystalline properties of the films are tailored through a judicial selection of the materials and the processing conditions and assessed by means of thermal analyses, polarized optical microscopy, scanning electron microscopy and confocal interferometric microscopy. The results show that the morphological and crystalline properties of the films are strongly dependent on the choice of both the polymer/solvent system and the operating conditions during the drying step. In particular, the morphological, topographical and thermal properties of films prepared starting from highly crystalline polymers, namely PCL and PEO, are greatly affected by the crystallization of the material. Conversely, the less crystalline PLA forms almost completely amorphous films.

  15. Impact of solvents and supercritical CO2 drying on the morphology and structure of polymer-based biofilms

    NASA Astrophysics Data System (ADS)

    Causa, Andrea; Salerno, Aurelio; Domingo, Concepción; Acierno, Domenico; Filippone, Giovanni

    2014-05-01

    In the present work, two-dimensional systems based on biodegradable polymers such as poly(ɛ-caprolactone) (PCL), poly(ethylene oxide) (PEO) and polylactic acid (PLA) are fabricated by means of a sustainable approach which consists in inducing phase separation in solutions of such polymers and "green" solvents, namely ethyl lactate (EL) and ethyl acetate (EA). The extraction of the solvent is promoted by a controlled drying process, which is performed in either air or supercritical CO2. The latter can indeed act as both an antisolvent, which favors the deposition of the polymer by forming a mixture with EL and EA, and a plasticizing agent, whose solvation and transport properties may considerably affect the microstructure and crystallinity of the polymer films. The morphological, topographical and crystalline properties of the films are tailored through a judicial selection of the materials and the processing conditions and assessed by means of thermal analyses, polarized optical microscopy, scanning electron microscopy and confocal interferometric microscopy. The results show that the morphological and crystalline properties of the films are strongly dependent on the choice of both the polymer/solvent system and the operating conditions during the drying step. In particular, the morphological, topographical and thermal properties of films prepared starting from highly crystalline polymers, namely PCL and PEO, are greatly affected by the crystallization of the material. Conversely, the less crystalline PLA forms almost completely amorphous films.

  16. Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

    NASA Astrophysics Data System (ADS)

    Cha, Kyoung Je; Kim, Taewan; Jea Park, Sung; Kim, Dong Sung

    2014-11-01

    Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications.

  17. Cellular behavior of neointima-like cells onto vitamin E-enriched poly(D,L)lactic acid.

    PubMed

    Renò, Filippo; Traina, Vincenzina; Cannas, Mario

    2007-09-01

    In-stent restenosis is a process that occurs in 10-50% of cases currently treated with stent and it is caused by an abnormal smooth muscle cell (SMC) proliferation and migration in the vascular lumen. One of the most promising strategy to reduce restenosis is stent coating with biodegradable polymers to deliver in situ anti-proliferative drugs. Poly(D,L)lactic acid (P(D,L)LA), one of the most interesting candidate for stent coating, has been observed to induce inflammation and neointimal proliferation. In our laboratory, we developed P(D,L)LA enriched with Vitamin E (Vit.E), an anti-oxidative and anti-inflammatory agent that reduces also SMC proliferation. In order to evaluate the in vitro cellular behaviour of neointima cells onto Vitamin E-enriched P(D,L)LA, cell adhesion and proliferation along with the expression of two SMC migration markers (MMP-9 and hyaluronic acid receptor CD44) were measured in rat vascular SMC A10 cells seeded onto control P(D,L)LA (PLA) and P(D,L)LA films containing 10-30% (w/w) Vit.E (PLA10-30). Cell adhesion, proliferation and MMP-9 production were unaffected by the Vit.E presence in the PLA films after 24 h, while proliferation was slowed or blocked after 48 and 72 h onto PLA10, 20 and 30. MMP-9 production was almost blocked and CD44 density decreased significantly after 72 h for cells grew onto PLA30 compare to cells seeded onto PLA. These data indicate that Vit.E-enriched P(D,L)LA could be an interesting polymer for stent coating.

  18. Investigation of crystallinity, molecular weight change, and mechanical properties of PLA/PBG bioresorbable composites as bone fracture fixation plates.

    PubMed

    Felfel, Reda M; Ahmed, Ifty; Parsons, Andrew J; Haque, Papia; Walker, Gavin S; Rudd, Chris D

    2012-03-01

    In this study, bioresorbable phosphate-based glass (PBG) fibers were used to reinforce poly(lactic acid) (PLA). PLA/PBG random mat (RM) and unidirectional (UD) composites were prepared via laminate stacking and compression molding with fiber volume fractions between 14% and 18%, respectively. The percentage of water uptake and mass change for UD composites were higher than the RM composites and unreinforced PLA. The crystallinity of the unreinforced PLA and composites increased during the first few weeks and then a plateau was seen. XRD analysis detected a crystalline peak at 16.6° in the unreinforced PLA sample after 42 days of immersion in phosphate buffer solution (PBS) at 37°C. The initial flexural strength of RM and UD composites was ∼106 and ∼115 MPa, whilst the modulus was ∼6.7 and ∼9 GPa, respectively. After 95 days immersion in PBS at 37°C, the strength decreased to 48 and 52 MPa, respectively as a result of fiber-matrix interface degradation. There was no significant change in flexural modulus for the UD composites, whilst the RM composites saw a decrease of ∼45%. The molecular weight of PLA alone, RM, and UD composites decreased linearly with time during degradation due to chain scission of the matrix. Short fiber pull-out was seen from SEM micrographs for both RM and UD composites.

  19. Grafting of poly (lactic acid) with maleic anhydride using supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Khankrua, R.; Pivsa-Art, S.; Hiroyuki, H.; Suttiruengwong, S.

    2015-07-01

    The aim of this work was to modify poly lactic acid (PLA) via free radical grafting with maleic anhydride (MA) by using supercritical carbon dioxide (SCCO2). Benzoyl peroxide (BPO) was used as an initiator. The solubility of MA in SCCO2 was first determined to estimate the suitable grafting conditions and equilibrium. From the solubility study of MA in SCCO2, it was found that the solubility of MA in SCCO2 increased with the increasing pressure and dissolution time. PLA films were first prepared by compression molding. The ratio of MA to BPO was 2:1. The reaction temperature and pressure were 70°C and 100 bar respectively. The grafting reaction and the degree of grafting were characterized by nuclear magnetic resonance (NMR) spectroscopy and titration, respectively. Scanning electron microscope (SEM) technique and contact angle were used to confirm the changes in physical properties of PLA film grafted MA. NMR spectrum indicated that the grafting of MA onto PLA was successively achieved. Degree of grafting by using SCCO2 was as high as 0.98%. This provided rather high grafting degree compared with other processes. SEM pictures showed the rough surface structure on modified PLA film. In addition, contact angle results showed an improvement of the hydrophilicity by maleic anhydride grafting onto polymers.

  20. Application of molecularly imprinted polymers to selective removal of clofibric acid from water.

    PubMed

    Dai, Chaomeng; Zhang, Juan; Zhang, Yalei; Zhou, Xuefei; Liu, Shuguang

    2013-01-01

    A new molecularly imprinted polymer (MIP) adsorbent for clofibric acid (CA) was prepared by a non-covalent protocol. Characterization of the obtained MIP was achieved by scanning electron microscopy (SEM) and nitrogen sorption. Sorption experimental results showed that the MIP had excellent binding affinity for CA and the adsorption of CA by MIP was well described by pseudo-second-order model. Scatchard plot analysis revealed that two classes of binding sites were formed in the MIP with dissociation constants of 7.52 ± 0.46 mg L(-1) and 114 ± 4.2 mg L(-1), respectively. The selectivity of MIP demonstrated higher affinity for CA over competitive compound than that of non-imprinted polymers (NIP). The MIP synthesized was used to remove CA from spiked surface water and exhibited significant binding affinity towards CA in the presence of total dissolved solids (TDS). In addition, MIP reusability was demonstrated for at least 12 repeated cycles without significant loss in performance.

  1. Polymer electrolyte membrane based on 2-acrylamido-2-methyl propanesulfonic acid fabricated by embedded polymerization

    NASA Astrophysics Data System (ADS)

    Pei, Haiqin; Hong, Liang; Lee, Jim Yang

    Methanol crossover through the Nafion membrane is a perennial problem in the operation of direct methanol fuel cells (DMFCs) and therefore justifies the search for a Nafion substitute. This study reports a new methanol-blocking polymer matrix which consists of a methanol barrier phase and an embedded proton source. A three-component polymer blend (TCPB) of poly(4-vinylphenol-co-methyl methacrylate), poly(butyl methacrylate) (PBMA), and Paraloid ® B-82 acrylic copolymer resins is used as a methanol barrier. In order to implant a proton source in the membrane as homogeneously as possible, the hydrophilic monomers, 2-acrylamido-2-methyl propanesulfonic acid (AMPS), 2-hydroxyethyl methacrylate (HEMA) and a cross-linking agent (poly(ethylene glycol) dimethylacrylate) (PEGDMA) are polymerized after they have been embedded in the TCPB matrix. The embedded polymerization has resulted in an asymmetric membrane structure, in which the hydrophilic network is sandwiched by two outer layers of predominantly hydrophobic TCPB. Measurements are made of properties of the AMPS-containing membranes that are important to fuel cell applications such as water uptake, ion-exchange capacity, proton conductivity, methanol permeability and tensile strength. The highest proton conductivity of the AMPS-containing membrane is about 0.030 S cm -1 at 70 °C. The low methanol permeability (10 -8 to 10 -7 cm 2 s -1) of the AMPS-containing membranes is their primary advantage for DMFC applications.

  2. Nanocasting Design and Spatially Selective Sulfonation of Polystyrene-Based Polymer Networks as Solid Acid Catalysts.

    PubMed

    Richter, Felix H; Sahraoui, Laila; Schüth, Ferdi

    2016-09-12

    Nanocasting is a general and widely applied method in the generation of porous materials during which a sacrificial solid template is used as a mold on the nanoscale. Ideally, the resulting structure is the inverse of the template. However, replication is not always as direct as anticipated, so the influences of the degree of pore filling and of potential restructuring processes after removal of the template need to be considered. These apparent limitations give rise to opportunities in the synthesis of poly(styrene-co-divinylbenzene) (PSD) polymer networks of widely varying porosities (BET surface area=63-562 m(2)  g(-1) ; Vtot =0.18-1.05 cm(3)  g(-1) ) by applying a single synthesis methodology. In addition, spatially selective sulfonation on the nanoscale seems possible. Together, nanocasting and sulfonation enable rational catalyst design. The highly porous nanocast and predominantly surface-sulfonated PSD networks approach the activity of the corresponding molecular catalyst, para-toluenesulfonic acid, and exceed those of commercial ion-exchange polymers in the depolymerization of macromolecular inulin.

  3. Biodegradable Kojic Acid-Based Polymers: Controlled Delivery of Bioactives for Melanogenesis Inhibition.

    PubMed

    Faig, Jonathan J; Moretti, Alysha; Joseph, Laurie B; Zhang, Yingyue; Nova, Mary Joy; Smith, Kervin; Uhrich, Kathryn E

    2017-02-13

    Kojic acid (KA) is a naturally occurring fungal metabolite that is utilized as a skin-lightener and antibrowning agent owing to its potent tyrosinase inhibition activity. While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles. To minimize degradation, poly(carbonate-esters) and polyesters comprised of KA and natural diacids were prepared via solution polymerization methods. In vitro hydrolytic degradation analyses revealed KA release was drastically influenced by polymer backbone composition (e.g., poly(carbonate-ester) vs polyester), linker molecule (aliphatic vs heteroatom-containing), and release conditions (physiological vs skin). Tyrosinase inhibition assays demonstrated that aliphatic KA dienols, the major degradation product under skin conditions, were more potent then KA itself. All dienols were found to be less toxic than KA at all tested concentrations. Additionally, the most lipophilic dienols were statistically more effective than KA at inhibiting melanin biosynthesis in cells. These KA-based polymer systems deliver KA analogues with improved efficacy and cytocompatible profiles, making them ideal candidates for sustained topical treatments in both medical and personal care products.

  4. Biocompatible hyaluronic acid polymer-coated quantum dots for CD44+ cancer cell-targeted imaging

    NASA Astrophysics Data System (ADS)

    Wang, Hening; Sun, Hongfang; Wei, Hui; Xi, Peng; Nie, Shuming; Ren, Qiushi

    2014-10-01

    The cysteamine-modified hyaluronic acid (HA) polymer was employed to coat quantum dots (QDs) through a convenient one-step reverse micelle method, with the final QDs hydrodynamic size of around 22.6 nm. The HA coating renders the QDs with very good stability in PBS for more than 140 days and resistant to large pH range of 2-12. Besides, the HA-coated QDs also show excellent fluorescence stability in BSA-containing cell culture medium. In addition, the cell culture assay indicates no significant cytotoxicity for MD-MB-231 breast cancer cells, and its targeting ability to cancer receptor CD44 has been demonstrated on two breast cancer cell lines. The targeting mechanism was further proved by the HA competition experiment. This work has established a new approach to help solve the stability and toxicity problems of QDs, and moreover render the QDs cancer targeting property. The current results indicate that the HA polymer-coated QDs hold the potential application for both in vitro and in vivo cancer imaging researches.

  5. Nanoporous linear polyethylene from a block polymer precursor.

    PubMed

    Pitet, Louis M; Amendt, Mark A; Hillmyer, Marc A

    2010-06-23

    Porous polyolefin membranes play an integral role in lithium-ion battery technology as the barrier preventing direct anode and cathode contact. Block polymers containing a sacrificial component have proven to be attractive precursors for nanoporous polymer membranes stemming from their unique ability to self-assemble into mesoscopically organized structures. Selective removal of the sacrificial component can leave a scaffold with well-controlled pore dimensions and porosity. This communication describes the synthesis of block polymers containing polylactide (PLA) as the sacrificial component and perfectly linear polyethylene (LPE) as the matrix phase using a combination of ring-opening polymerizations. Bicontinuous morphologies accessible over a broad composition range allow for ready tailoring of porosity. Removal of the PLA results in semicrystalline LPE with an interpenetrating void space having pore dimensions less than 100 nm. The porosity and domain size dependence on composition was corroborated by nitrogen adsorption and scanning electron microscopy. The mechanical robustness of the nanoporous samples was confirmed by tensile testing. The outstanding chemical resistance of the nanoporous LPE samples was demonstrated by treatment with concentrated strong acids over extended periods (approximately 1 day).

  6. Core-shell nanofibers of curcumin/cyclodextrin inclusion complex and polylactic acid: Enhanced water solubility and slow release of curcumin.

    PubMed

    Aytac, Zeynep; Uyar, Tamer

    2017-02-25

    Core-shell nanofibers were designed via electrospinning using inclusion complex (IC) of model hydrophobic drug (curcumin, CUR) with cyclodextrin (CD) in the core and polymer (polylactic acid, PLA) in the shell (cCUR/HPβCD-IC-sPLA-NF). CD-IC of CUR and HPβCD was formed at 1:2 molar ratio. The successful formation of core-shell nanofibers was revealed by TEM and CLSM images. cCUR/HPβCD-IC-sPLA-NF released CUR slowly but much more in total than PLA-CUR-NF at pH 1 and pH 7.4 due to the restriction of CUR in the core of nanofibers and solubility improvement shown in phase solubility diagram, respectively. Improved antioxidant activity of cCUR/HPβCD-IC-sPLA-NF in methanol:water (1:1) is related with the solubility enhancement achieved in water based system. The slow reaction of cCUR/HPβCD-IC-sPLA-NF in methanol is associated with the shell inhibiting the quick release of CUR. On the other hand, cCUR/HPβCD-IC-sPLA-NF exhibited slightly higher rate of antioxidant activity than PLA-CUR-NF in methanol:water (1:1) owing to the enhanced solubility. To conclude, slow release of CUR was achieved by core-shell nanofiber structure and inclusion complexation of CUR with HPβCD provides high solubility. Briefly, electrospinning of core-shell nanofibers with CD-IC core could offer slow release of drugs as well as solubility enhancement for hydrophobic drugs.

  7. A New Structural Family of Gas-Sorbing Coordination Polymers Derived from Phenolic Carboxylic Acids.

    PubMed

    White, Keith F; Abrahams, Brendan F; Babarao, Ravichandar; Dharma, A David; Hudson, Timothy A; Maynard-Casely, Helen E; Robson, Richard

    2015-12-07

    The structure of Li(inox)⋅2/3 DMF (inox(-) =the N-oxide of the isonicotinate anion) consists of a 3D framework with solvent-filled, square cross-section channels of approximate dimensions 5.5×5.5 Å. Unfortunately, the Li(inox) framework is unstable upon removal of DMF from the channels. When the structurally related 4-hydroxybenzoic acid (H2 hba) was used in place of Hinox, and Zn(2+) in place of the Li(+) , a structurally similar but more robust network, Zn(hba), was obtained; the isostructural compound, Co(hba), may also be prepared. Longer ligands with phenolate and carboxylate functional groups at opposite ends, such as the dianions of 4-coumaric acid (H2 cma) and 4'-hydroxy-4-biphenylcarboxylic acid (H2 hbpc), in combination with Zn(2+) yield Zn(cma) and Zn(hbpc) frameworks, respectively, with the same PtS topology but with larger channels. The coordination polymers remain intact after desolvation and exhibit microporosity, showing the ability to sorb significant quantities of CO2 , CH4 , and H2 .

  8. Fluorescence measurements of activity associated with a molecularly imprinted polymer imprinted to dipicolinic acid

    NASA Astrophysics Data System (ADS)

    Anderson, John; Pestov, Dmitry; Fischer, Robert L.; Webb, Stanley; Tepper, Gary C.

    2004-03-01

    Steady state and lifetime fluorescence measurements were acquired to measure the binding activity associated with molecularly imprinted polymer (MIP) microparticles imprinted to dipicolinic acid. Dipicolinic acid is a unique compound associated with the sporulation phase of spore-forming bacteria (e.g., genus Bacillus and Clostridium). Vinylic monomers were polymerized in a dimethylformamide solution containing the dipicolinic acid as a template. The resulting MIP was then pulverized and size selected into small microscale particles. Samplers were adapted incorporating the MIP particles within a dialyzer (500 MW). Tests were run on replicate samples of biologically active cultures representing both stationary phase and sporulation post fermentation products in standard media. The permeability of the membrane permitted diffusion of lighter molecular weight constituents from media effluents to enter the dialyzer chamber and contact the MIP. Extractions of the media were measured using steady state and lifetime fluorescence. Results showed dramatic steady state fluorescence changes as a function of excitation, emission and intensity and an estimated lifetime of 5.8 ns.

  9. BmPLA2 containing conserved domain WD40 affects the metabolic functions of fat body tissue in silkworm, Bombyx mori.

    PubMed

    Orville Singh, Chabungbam; Xin, Hu-Hu; Chen, Rui-Ting; Wang, Mei-Xian; Liang, Shuang; Lu, Yan; Cai, Zi-Zheng; Miao, Yun-Gen

    2016-02-01

    PLA2 enzyme hydrolyzes arachidonic acid, and other polyunsaturated fatty acids, from the sn-2 position to release free arachidonic acid and a lysophospholipid. Previous studies reported that the PLA2 in invertebrate organisms participates in lipid signaling molecules like arachidonic acid release in immune-associated tissues like hemocytes and fat bodies. In the present study, we cloned the BmPLA2 gene from fat body tissue of silkworm Bombyx mori, which has a total sequence of 1.031 kb with a 31.90 kDa protein. In silico results of BmPLA2 indicated that the protein has a putative WD40 conserved domain and its phylogeny tree clustered with Danaus plexippus species. We investigated the transcriptional expression in development stages and tissues. The highest expression of BmPLA2 was screened in fat body among the studied tissues of third day fifth instar larva, with a high expression on third day fifth instar larva followed by a depression of expression in the wandering stage of the fifth instar larva. The expression of BmPLA2 in female pupa was higher than that of male pupa. Our RNAi-mediated gene silencing results showed highest reduction of BmPLA2 expression in post-24 h followed by post-48 and post-72 h. The BmPLA2-RNAi larvae and pupa could be characterized by pharate adult lethality and underdevelopment. The phenotypic characters of fat body cells in RNAi-induced larva implied that BmPLA2 affects the metabolic functions of fat body tissue in silkworm Bombyx mori.

  10. Photopolymerisation and characterization of maleylatedcellulose-g-poly(acrylic acid) superabsorbent polymer.

    PubMed

    Sawut, Amatjan; Yimit, Mamatjan; Sun, Wanfu; Nurulla, Ismayil

    2014-01-30

    A novel biodegradable superabsorbent polymer has been prepared from maleylated cotton stalk cellulose (MCSC) crosslinker and acrylic acid (AA) by ultraviolet (UV) photopolymerization in aqueous solution at room temperature, and irgacure 651 as a photoinitiator. The resulting superabsorbent was characterized by FT-IR, (1)H NMR, SEM and TGA. The effects of preparation conditions such as degree of substitution (DS), amount of maleylated cotton stalk cellulose, exposed time, photoinitiator amount and monomer concentration on the water absorbency and the monomer conversion in graft were evaluated. The swelling kinetics, salt-resistance, water retention capacity and biodegradability of the MCSC-g-PAA superabsorbent were investigated. It was found that, the obtained superabsorbent have good swelling degree that greatly affected by its composition and preparation conditions. Owing to its considerable good water retention capacity, being economical and environment-friendly, it might be useful for its application in agriculture field.

  11. Chirality-Discriminated Conductivity of Metal-Amino Acid Biocoordination Polymer Nanowires.

    PubMed

    Zheng, Jianzhong; Wu, Yijin; Deng, Ke; He, Meng; He, Liangcan; Cao, Jing; Zhang, Xugang; Liu, Yaling; Li, Shunxing; Tang, Zhiyong

    2016-09-27

    Biocoordination polymer (BCP) nanowires are successfully constructed through self-assembly of chiral cysteine amino acids and Cd cations in solution. The varied chirality of cysteine is explored to demonstrate the difference of BCP nanowires in both morphology and structure. More interestingly and surprisingly, the electrical property measurement reveals that, although all Cd(II)/cysteine BCP nanowires behave as semiconductors, the conductivity of the Cd(II)/dl-cysteine nanowires is 4 times higher than that of the Cd(II)/l-cysteine or Cd(II)/d-cysteine ones. The origin of such chirality-discriminated characteristics registered in BCP nanowires is further elucidated by theoretical calculation. These findings demonstrate that the morphology, structure, and property of BCP nanostructures could be tuned by the chirality of the bridging ligands, which will shed light on the comprehension of chirality transcription as well as construction of chirality-regulated functional materials.

  12. Copper coordination polymers constructed from thiazole-5-carboxylic acid: Synthesis, crystal structures, and structural transformation

    NASA Astrophysics Data System (ADS)

    Meundaeng, Natthaya; Rujiwatra, Apinpus; Prior, Timothy J.

    2017-01-01

    We have successfully prepared crystals of thiazole-5-carboxylic acid (5-Htza) (L) and three new thiazole-5-carboxylate-based Cu2+ coordination polymers with different dimensionality, namely, 1D [Cu2(5-tza)2(1,10-phenanthroline)2(NO3)2] (1), 2D [Cu(5-tza)2(MeOH)2] (2), and 3D [Cu(5-tza)2]·H2O (3). These have been characterized by single crystal X-ray diffraction and thermogravimetry. Interestingly, the 2D network structure of 2 can directly transform into the 3D framework of 3 upon removal of methanol molecules at room temperature. 2 can also undergo structural transformation to produce the same 2D network present in the known [Cu(5-tza)2]·1.5H2O upon heat treatment for 2 h. This 2D network can adsorb water and convert to 3 upon exposure to air.

  13. Syntheses and structures of three transition metal coordination polymers based on 5-Aminonicotinic acid

    NASA Astrophysics Data System (ADS)

    Jiang, Ya-Hui; Wu, Wei-Ping; Yang, Guo-Ping; Jin, Jun-Cheng; Xi, Zheng-Ping; Wang, Yao-Yu

    2015-07-01

    Three new coordination polymers (CPs) based on rigid ligand 5-Aminonicotinic acid (5-anaH), [Cd(5-ana)2]·(H2O)2 (1), [Cd(5-ana)(HCOO) ] (2) and [Cu(5-ana)2] (3), have been synthesized under different solvent media and temperatures. All CPs are characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, powder X-ray diffraction and thermogravimetric analysis. Compound 1 is a two-dimensional (2D) (4,4)-connected layered structure contains 1D open channels. 2 shows a 2-nodal (3,5)-connected three-dimensional (3D) framework with {52·6}{53·63·73·8} topology. While 3 displays a 3D (3,6)-connected homochiral framework with {42·6}2{44·62·85·104} topology. The solid-state photoluminescence for 1 and 2 were also studied.

  14. The graft polymers from different species of lignin and acrylic acid: synthesis and mechanism study.

    PubMed

    Ye, De zhan; Jiang, Li; Ma, Chao; Zhang, Ming-hua; Zhang, Xi

    2014-02-01

    The influence of lignin species on the grafting mechanism of lignosulfonate (from eucalyptus and pine, recorded as HLS and SLS, respectively) with acrylic acid (AA) was investigated. The graft polymers were confirmed by the absorption of carbonyl groups in the FTIR spectra. The decreasing phenolic group's content (Ph-OH) is not only due to its participation as grafting site but also to the negative effect of initiator. In the initial period (0-60 min), HLS and SLS both accelerate the polymerization of AA. Additionally, Ph-OH group's content is proportional to product yield (Y%), monomer conversion (C%) and grafting efficiency (GE%), strongly indicating that it acts as active center. Nevertheless, compared with HLS, Y% and C% in SLS grafting system are lower though it has higher Ph-OH group's content, which is due to the quinonoid structure formed by the self-conjugated of phenoxy radical in Guaiacyl unit. Finally, the lignosulfonate grafting mechanism was proposed.

  15. Multi-objective optimization and design of experiments as tools to tailor molecularly imprinted polymers specific for glucuronic acid.

    PubMed

    Kunath, Stephanie; Marchyk, Nataliya; Haupt, Karsten; Feller, Karl-Heinz

    2013-02-15

    We present a multi-objective optimization of the binding properties of a molecularly imprinted polymer (MIP) which specifically binds glucuronic acid (GA). A design of experiments approach is used to improve four different parameters that describe the binding properties of the polymer. Eleven different methacrylamide-co-ethyleneglycol dimethacrylate polymers imprinted with GA were synthesized according to a full factorial experimental design plan with 3 influencing factors (degree of cross-linking, molar equivalent of monomer to template and initiator concentration). These polymers were characterized by adsorption of the radiolabeled target analyte in methanol:water 9:1. The binding parameters were computed to optimize the polymer composition, taking into account four objective variables: the maximum binding capacity at high (Bmax) and low (B2) analyte concentrations, the equilibrium constant K50, and the imprinting factor (IF, binding to MIP/binding to NIP). With the multi-objective optimization method based on a desirability approach the composition of a twelfth "ideal" polymer could be predicted. This predicted polymer with highest "desirability" was synthesized with a composition of 0.65 mol% of initiator and a 1:4:20 ratio of template:functional monomers:cross-linker (T:M:X) (80% of cross-linking), and found to be the overall best MIP. Improvements over the original starting polymer were a 6 times lower K50, which corresponds to higher affinity, 20% higher capacity at low analyte concentration (B2), 40% higher capacity (Bmax) and 1.3 times increased imprinting factor (IF). Binding assays were also performed in aqueous solvents. Good binding properties were obtained in pure water with an imprinting factor of 3.2. Thus, this polymer is potentially applicable to biological samples like urine where glucuronides occur.

  16. Research on the Changes to the Lipid/Polymer Membrane Used in the Acidic Bitterness Sensor Caused by Preconditioning

    PubMed Central

    Harada, Yuhei; Noda, Junpei; Yatabe, Rui; Ikezaki, Hidekazu; Toko, Kiyoshi

    2016-01-01

    A taste sensor that uses lipid/polymer membranes can evaluate aftertastes felt by humans using Change in membrane Potential caused by Adsorption (CPA) measurements. The sensor membrane for evaluating bitterness, which is caused by acidic bitter substances such as iso-alpha acid contained in beer, needs an immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning”. However, what happens to the lipid/polymer membrane during MSG preconditioning is not clear. Therefore, we carried out three experiments to investigate the changes in the lipid/polymer membrane caused by the MSG preconditioning, i.e., measurements of the taste sensor, measurements of the amount of the bitterness substance adsorbed onto the membrane and measurements of the contact angle of the membrane surface. The CPA values increased as the preconditioning process progressed, and became stable after 3 d of preconditioning. The response potentials to the reference solution showed the same tendency of the CPA value change during the preconditioning period. The contact angle of the lipid/polymer membrane surface decreased after 7 d of MSG preconditioning; in short, the surface of the lipid/polymer membrane became hydrophilic during MSG preconditioning. The amount of adsorbed iso-alpha acid was increased until 5 d preconditioning, and then it decreased. In this study, we revealed that the CPA values increased with the progress of MSG preconditioning in spite of the decrease of the amount of iso-alpha acid adsorbed onto the lipid/polymer membrane, and it was indicated that the CPA values increase because the sensor sensitivity was improved by the MSG preconditioning. PMID:26891299

  17. Preparation and application of molecularly imprinted polymer for isolation of chicoric acid from Chicorium intybus L. medicinal plant.

    PubMed

    Saad, Engy M; Madbouly, Adel; Ayoub, Nahla; El Nashar, Rasha Mohamed

    2015-06-02

    Molecularly imprinted polymer (MIP) was synthesized and applied for the extraction of chicoric acid from Chicory herb (Chicorium intybus L.). A computational study was developed to find a suitable template to functional monomer molar ratio for MIP preparations. The molar ratio was chosen based on the comparison of the binding energy of the complexes between the template and functional monomers. Based on the computational results, eight different polymers were prepared using chicoric acid as the template. The MIPs were synthesized in a non-covalent approach via thermal free-radical polymerization, using two different polymerization methods, bulk and suspension. Batch rebinding experiments were performed to evaluate the binding properties of the imprinted polymers. The best results were obtained with a MIP prepared using bulk polymerization with 4-vinylpyridine (4-VP) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker with a molar ratio of 1:4:20. The best MIP showed selective binding ability toward chicoric acid in the presence of the template's structural analogues, caffeic acid, caftaric acid and chlorogenic acid.

  18. Release mechanisms of tacrolimus-loaded PLGA and PLA microspheres and immunosuppressive effects of the microspheres in a rat heart transplantation model.

    PubMed

    Kojima, Ryo; Yoshida, Takatsune; Tasaki, Hiroaki; Umejima, Hiroyuki; Maeda, Masashi; Higashi, Yasuyuki; Watanabe, Shunsuke; Oku, Naoto

    2015-08-15

    The objective of this study was to elucidate the release and absorption mechanisms of tacrolimus loaded into microspheres composed of poly(lactic-co-glycolic acid) (PLGA) and/or polylactic acid (PLA). Tacrolimus-loaded microspheres were prepared by the o/w emulsion solvent evaporation method. The entrapment efficiency correlated with the molecular weight of PLGA, and the glass transition temperature of PLGA microspheres was not decreased by the addition of tacrolimus. These results indicate that intermolecular interaction between tacrolimus and the polymer would affect the entrapment of tacrolimus in the microspheres. Tacrolimus was released with weight loss of the microspheres, and the dominant release mechanism of tacrolimus was considered to be erosion of the polymer rather than diffusion of the drug. The whole-blood concentration of tacrolimus in rats was maintained for at least 2 weeks after a single subcutaneous administration of the microspheres. The pharmacokinetic profile of tacrolimus following subcutaneous administration was similar to that following intramuscular administration, suggesting that the release and dissolution of tacrolimus, rather than the absorption of the dissolved tacrolimus, were rate-limiting steps. Graft-survival time in a heart transplantation rat model was prolonged by the administration of tacrolimus-loaded microspheres. The microsphere formulation of tacrolimus would be expected to precisely control the blood concentration while maintaining the immunosuppressive effect of the drug.

  19. In situ formation and gelation mechanism of thermoresponsive stereocomplexed hydrogels upon mixing diblock and triblock poly(lactic acid)/poly(ethylene glycol) copolymers.

    PubMed

    Mao, Hailiang; Pan, Pengju; Shan, Guorong; Bao, Yongzhong

    2015-05-28

    A novel in situ formed gel system with potential biodegradability and biocompatibility is developed by mixing the diblock and triblock poly(lactic acid)/poly(ethylene glycol) (PLA/PEG) copolymers with opposite configurations of PLA blocks. In situ gelation of such system is extremely fast, which happens within 10 s after mixing. In situ gelation, gel-to-sol transition, crystalline structure, microstructures, and mechanical properties of PLA-PEG/PLA-PEG-PLA enantiomerically mixed gels are significantly influenced by the mixing ratio, degree of polymerization for PEG block in triblock (DPPEG,tri) and diblock copolymers (DPPEG,di). It is found that in situ gelation of PLA-PEG/PLA-PEG-PLA enantiomeric mixture just happen at relatively smaller PLA-PEG/PLA-PEG-PLA mass ratio and larger DPPEG,tri. Hydrodynamic diameters of PLA-PEG and PLA-PEG-PLA copolymers in dilute solution increase remarkably upon mixing, indicating the formation of bridging networks. Stereocomplexed crystallites are formed for the PLA hydrophobic domains in PLA-PEG/PLA-PEG-PLA enantiomeric mixtures. As indicated by synchrotron-radiation SAXS analysis, the enantiomeric mixture changes from a compactly to loosely aggregated structure and the intermicellar distance enhances with increasing DPPEG,tri, DPPEG,di, or PLA-PEG-PLA fraction. Gelation mechanism of PLA-PEG/PLA-PEG-PLA enantiomeric mixture is proposed, in which part of PLA-PEG-PLA chains act as the connecting bridges between star and flower-like micelles and the stereocomplexed crystallites in micelle cores act as physically cross-linked points.

  20. Development of biodegradable metaloxide/polymer nanocomposite films based on poly-ε-caprolactone and terephthalic acid.

    PubMed

    Varaprasad, Kokkarachedu; Pariguana, Manuel; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Sadiku, Emmanuel Rotimi

    2017-01-01

    The present investigation describes the development of metal-oxide polymer nanocomposite films from biodegradable poly-ε-caprolactone, disposed poly(ethylene terephthalate) oil bottles monomer and zinc oxide-copper oxide nanoparticles. The terephthalic acid and zinc oxide-copper oxide nanoparticles were synthesized by using a temperature-dependent precipitation technique and double precipitation method, respectively. The terephthalic acid synthesized was confirmed by FTIR analysis and furthermore, it was characterized by thermal analysis. The as-prepared CuO-ZnO nanoparticles structure was confirmed by XRD analysis and its morphology was analyzed by SEM/EDS and TEM. Furthermore, the metal-oxide polymer nanocomposite films have excellent mechanical properties, with tensile strength and modulus better than pure films. The metal-oxide polymer nanocomposite films that were successfully developed show a relatively brighter colour when compared to CuO film. These new metal-oxide polymer nanocomposite films can replace many non-degradable plastics. The new metal-oxide polymer nanocomposite films developed are envisaged to be suitable for use in industrial and domestic packaging applications.

  1. Surface characterization and cell response of a PLA/CaP glass biodegradable composite material.

    PubMed

    Navarro, M; Engel, E; Planell, J A; Amaral, I; Barbosa, M; Ginebra, M P

    2008-05-01

    Bioabsorbable materials are of great interest for bone regeneration applications, since they are able to degrade gradually as new tissue is formed. In this work, a fully biodegradable composite material containing polylactic acid (PLA) and calcium phosphate (CaP) soluble glass particles has been characterized in terms of surface properties and cell response. Cell cultures were performed in direct contact with the materials and also with their extracts, and were evaluated using the MTT assay, alkaline phosphatase activity, and osteocalcin measurements. The CaP glass and PLA were used as reference materials. No significant differences were observed in cell proliferation with the extracts containing the degradation by-products of the three materials studied. A relation between the materials wettability and the material-cell interactions at the initial stages of contact was observed. The most hydrophilic material (CaP glass) presented the highest cell adhesion values as well as an earlier differentiation, followed by the PLA/glass material. The incorporation of glass particles into the PLA matrix increased surface roughness. SEM images showed that the heterogeneity of the composite material induced morphological changes in the cells cytoskeleton.

  2. Effects of modified cellulose nanocrystals on the barrier and migration properties of PLA nano-biocomposites.

    PubMed

    Fortunati, E; Peltzer, M; Armentano, I; Torre, L; Jiménez, A; Kenny, J M

    2012-10-01

    The aim of this paper is to report the impact of the addition of cellulose nanocrystals on the barrier properties and on the migration behaviour of poly(lactic acid), PLA, based nano-biocomposites prepared by the solvent casting method. Their microstructure, crystallinity, barrier and overall migration properties were investigated. Pristine (CNC) and surfactant-modified cellulose nanocrystals (s-CNC) were used, and the effect of the cellulose modification and content in the nano-biocomposites was investigated. The presence of surfactant on the nanocrystal surface favours the dispersion of CNC in the PLA matrix. Electron microscopy analysis shows the good dispersion of s-CNC in the nanoscale with well-defined single crystals indicating that the surfactant allowed a better interaction between the cellulose structures and the PLA matrix. Reductions of 34% in water permeability were obtained for the cast films containing 1 wt.% of s-CNC while good oxygen barrier properties were detected for nano-biocomposites with both 1 wt.% and 5 wt.% of modified and un-modified cellulose nanocrystals, underlining the improvement provided by cellulose on the PLA films. Moreover, the migration level of the studied nano-biocomposites was below the overall migration limits required by the current normative for food packaging materials in both non-polar and polar simulants.

  3. Correlation between crystallization behaviour and interfacial interactions in plasticized PLA/POSS nanocomposites

    NASA Astrophysics Data System (ADS)

    Kodal, Mehmet; Şirin, Hümeyra; Özkoç, Güralp

    2016-03-01

    In this study, the correlation between crystallization behavior and surface chemistry of polyhedral oligomeric silsesquioxanes (POSS) for plasticized poly(lactic acid) (PLA)/POSS nanocomposites was investigated. Four different kinds of POSS particles having different chemical structures were used. Poly(ethylene glycol) (PEG, 8000 g/mol) was utilized as the plasticiser. The nanocomposites were melt-compounded in an Xplore Instruments 15 cc twin screw microcompounder at 180°C barrel temperature and 100 rpm screw speed. Non-isothermal crystallization behaviour of PLA/PEG/POSS nanocomposites were evaluated from common kinetic models such as Avrami and Avrami-Ozawa and Kissinger by using the thermal data obtained from differantial scanning calorimetry (DSC). A polarized optical microscope (POM) equipped with a hot-stage was used to examine the morphology during the crystal growth. In order to investigate the interfacial interactions between POSS particles and plasticized PLA, thermodynamic work of adhesion approach was adopted using the experimentally determined surface energies. A strong correlation was obtained between interfacial chemistry and the nucleation rate in plasticized PLA/POSS nanocomposites. It was found that the polar interactions were the dominating factor which determines the nucleation activity of the POSS particles.

  4. Three coordination polymers constructed from 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid: Synthesis, crystal structure and properties

    NASA Astrophysics Data System (ADS)

    Zhai, Dandan; Sun, Wujuan; Fan, Fei; Liao, Xuzhao; Chen, Sanping; Yang, Xuwu

    2017-04-01

    Three new coordination polymers, namely, {[Co2(TPA)(μ3-O)3]·0.5DMA}n (1), {[Co(H2TPA)(bibp)(H2O)3]·H2O}n (2) and {[Cd3(TPA)2(phen)4]·4H2O}n (3), (H3TPA = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid, bibp = 4,4'-bis(imidazolyl)biphenyl, phen = 1,10-phenanthroline and DMA = N,N-dimethylacetamide), have been synthesized under solvothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction analysis. Polymer 1 exhibits a three-dimensional (3D) structure constructed from 5-connected secondary building units (SBUs) [Co3(μ3-O)] and 3-connected H3TPA ligands. Polymer 2 has a 1D zigzag polymer chain connected by H3TPA and bibp ligands. Polymer 3 features an unusual 3D framework with a (3,4,2)-connected {4; 6;8}{4; 62;83} topology. Moreover, the thermal stabilities of 1-3 and photoluminescence properties of 3 have been investigated. Magnetic susceptibility measurements indicate that polymers 1-2 display antiferromagnetic exchange properties.

  5. Bp-13 PLA2: Purification and Neuromuscular Activity of a New Asp49 Toxin Isolated from Bothrops pauloensis Snake Venom

    PubMed Central

    Sucasaca-Monzón, Georgina; Randazzo-Moura, Priscila; Rocha, Thalita; Vilca-Quispe, Augusto; Ponce-Soto, Luis Alberto; Marangoni, Sérgio; da Cruz-Höfling, Maria Alice; Rodrigues-Simioni, Léa

    2015-01-01

    A new PLA2 (Bp-13) was purified from Bothrops pauloensis snake venom after a single chromatographic step of RP-HPLC on μ-Bondapak C-18. Amino acid analysis showed a high content of hydrophobic and basic amino acids and 14 half-cysteine residues. The N-terminal sequence showed a high degree of homology with basic Asp49 PLA2 myotoxins from other Bothrops venoms. Bp-13 showed allosteric enzymatic behavior and maximal activity at pH 8.1, 36°–45°C. Full Bp-13 PLA2 activity required Ca2+; its PLA2 activity was inhibited by Mg2+, Mn2+, Sr2+, and Cd2+ in the presence and absence of 1 mM Ca2+. In the mouse phrenic nerve-diaphragm (PND) preparation, the time for 50% paralysis was concentration-dependent (P < 0.05). Both the replacement of Ca2+ by Sr2+ and temperature lowering (24°C) inhibited the Bp-13 PLA2-induced twitch-tension blockade. Bp-13 PLA2 inhibited the contractile response to direct electrical stimulation in curarized mouse PND preparation corroborating its contracture effect. In biventer cervicis preparations, Bp-13 induced irreversible twitch-tension blockade and the KCl evoked contracture was partially, but significantly, inhibited (P > 0.05). The main effect of this new Asp49 PLA2 of Bothrops pauloensis venom is on muscle fiber sarcolemma, with avian preparation being less responsive than rodent preparation. The study enhances biochemical and pharmacological characterization of B. pauloensis venom. PMID:25789175

  6. Chitosan/PLA nanoparticles as a novel carrier for the delivery of anthraquinone: synthesis, characterization and in vitro cytotoxicity evaluation.

    PubMed

    Jeevitha, D; Amarnath, Kanchana

    2013-01-01

    Designing novel materials for biomedical applications generally require the use of biodegradable materials. This study aims to engineer a biodegradable [chitosan (CS) and poly (lactic acid) (PLA)] as AQ carrier with nanometer dimensions and to evaluate the anticancer potency of the prepared CS/PLA-AQ NPs in human carcinoma (HepG2) cells. CS-PLA complex, which are well dispersed and stable in aqueous solution, was prepared by the precipitation of lactic acid in chitosan solution by dropping method and characterized by SEM, TEM, DLS and FTIR. The results thus displayed that the prepared nanoparticles carried a positive charge and showed the size in the range from 100 to 200 nm. The in vitro (AQ) release study showed that these nanoparticles provided a continuous release of the entrapped AQ for 10 days, and the release behavior was influenced by the pH value of the medium thereby making feasible to develop CS-PLA for enhanced and sustained release of AQ. MTT assay revealed higher cytotoxic efficacy of CS/PLA-AQ NPs than Free AQ in HepG2 cells. Further, the mitochondrial membrane damage indicated by loss of mitochondrial membrane potential and necrotic cell death could be attributed to the increased reactive oxygen species production. Our results also suggest that upon CS/PLA-AQ NPs exposure the cell viability decreased due to apoptosis, as demonstrated by the formation of apoptotic bodies, sub-G1 hypodiploid cells, and DNA fragmentation. Henceforth, CS/PLA-AQ NPs demonstrated a strong antitumor activity in vitro by reducing cell viability, inducing cell necrosis, decreasing the negative surface charge and mitochondrial membrane potential, and fragmenting DNA.

  7. Tuning Surface Charge and PEGylation of Biocompatible Polymers for Efficient Delivery of Nucleic Acid or Adenoviral Vector.

    PubMed

    Choi, Joung-Woo; Kim, Jaesung; Bui, Quang Nam; Li, Yi; Yun, Chae-Ok; Lee, Doo Sung; Kim, Sung Wan

    2015-08-19

    As an effective and safe strategy to overcome the limits of therapeutic nucleic acid or adenovirus (Ad) vectors for in vivo application, various technologies to modify the surface of vectors with nonimmunogenic/biocompatible polymers have been emerging in the field of gene therapy. However, the transfection efficacy of the polymer to transfer genetic materials is still relatively weak. To develop more advanced and effective polymers to deliver not only Ad vectors, but also nucleic acids, 6 biocompatible polymers were newly designed and synthesized to different sizes (2k, 3.4k, or 5k) of poly(ethylene) glycol (PEG) and different numbers of amine groups (2 or 5) based on methoxy poly(ethylene glycol)-b-poly{N-[N-(2-aminoethyl)-2-aminoethyl]-l-glutamate (PNLG). We characterized size distribution and surface charge of 6 PNLGs after complexation with either nucleic acid or Ad. Among all 6 PNLGs, the 5 amine group PNLG showed the strongest efficacy in delivering nucleic acid as well as Ad vectors. Interestingly, cellular uptake results showed higher uptake ability in Ad complexed with 2 amine group PNLG than Ad/5 amine group PNLG, suggesting that the size of Ad/PNLGs is more essential than the surface charge for cellular uptake in polymers with charges greater than 30 mV. Moreover, the endosome escape ability of Ad/PNLGs increased depending on the number of amine groups, but decreased by PEG size. Cancer cell killing efficacy and immune response studies of oncolytic Ad/PNLGs showed 5 amine group PNLG to be a more effective and safe carrier for delivering Ad. Overall, these studies provide new insights into the functional mechanism of polymer-based approaches to either nucleic acid or Ad/nanocomplex. Furthermore, the identified ideal biocompatible PNLG polymer formulation (5 amine/2k PEG for nucleic acid, 5 amine/5k PEG for Ad) demonstrated high transduction efficiency as well as therapeutic value (efficacy and safety) and thus has strong potential for in vivo therapeutic

  8. Reduced graphene oxide/molecular imprinted polymer-organic thin film transistor for amino acid detection

    NASA Astrophysics Data System (ADS)

    Halim, Nurul Farhanah AB.; Musa, Nur Hazwani; Zakaria, Zulkhairi; Von Schleusingen, Mubaraq; Ahmad, Mohd Noor; Derman, Nazree; Shakaff, Ali Yeon Md.

    2017-03-01

    This works reports the electrical performance of reduced graphene oxide (RGO)/Molecular imprinted polymer (MIP)- organic thin film transistor (OTFT) for amino-acid detection, serine. These biomimetic sensors consider MIP as man-tailored biomimetic recognition sites that play an important role in signal transduction. MIP provides recognition sites compatible with serine molecules was developed by dispersing serine with methylacrylate acid (MAA) as functional monomer and Ethylene glycol dimethylacrylate (EGDMA) as cross-linker. The imprinted polymeric were mixed with reduced graphene oxide to produced sensing layer for the sensor. RGO-MIP layer was introduced between source and drain of OTFT via spin coating as a detecting layer for serine molecules. RGO was introduced into MIP, to allow a highly conductive sensing material thus enhanced selectivity and sensitivity of the sensor. By analyzing the electrical performance of the sensors, the performances of OTFT sensor enhanced with RGO/MIP interlayer and OTFT sensor with MIP interlayer when exposed to serine analyte were obtained. The results showed that there were remarkable shifts of drain current (ID) obtained from OTFT sensor with RGO/MIP interlayer after exposed to serine analyte. Moreover, the sensitivity of OTFT sensor with RGO/MIP interlayer was nearly higher than the OTFT sensor with MIP interlayer. Hence, it proved that RGO successfully enhanced the sensing performance of OTFT sensor.

  9. Simultaneous Reduction and Functionalization of Graphene Oxide by 4-Hydrazinobenzenesulfonic Acid for Polymer Nanocomposites

    PubMed Central

    Qiao, Song-Jie; Xu, Xiang-Nan; Qiu, Yang; Xiao, He-Chong; Zhu, Yue-Feng

    2016-01-01

    Graphene oxide (GO) was functionalized and reduced simultaneously by a new reductant, 4-hydrazinobenzenesulfonic acid (HBS), with a one-step and environmentally friendly process. The hydrophilic sulfonic acid group in HBS was grafted onto the surface of GO through a covalent bond. The successful preparation of HBS reduced GO (HBS-rGO) was testified by scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopic (XPS) and thermogravimetric analysis (TGA). The interlayer space of HBS-rGO was increased to 1.478 nm from 0.751 nm for GO, resulting in a subdued Van der Waals’ force between layers and less possibility to form aggregations. The aqueous dispersibility of graphene was improved to 13.49 mg/mL from 0.58 mg/mL after the functionalization. The viscosity of the epoxy resin based HBS-rGO composite could be regulated by an adjustment of the content of HBS-rGO. This study provides a new and applicable approach for the preparation of hydrophilic functionalized graphene, and makes it possible for the application of graphene in some functional polymer nanocomposites, such as specialty water-based coatings.

  10. Surface plasmon resonance sensor for domoic acid based on grafted imprinted polymer.

    PubMed

    Lotierzo, M; Henry, O Y F; Piletsky, S; Tothill, I; Cullen, D; Kania, M; Hock, B; Turner, A P F

    2004-09-15

    A molecularly imprinted polymer (MIP) film for domoic acid (DA) was synthesised by direct photo-grafting onto a gold chip suitable for a surface plasmon resonance (SPR) based bioanalytical instrument system, the BIAcore 3000. The gold surface was first functionalised with a self-assembled monolayer of 2-mercaptoethylamine and subsequent carbodiimide chemistry was performed for covalent attachment of the photoinitiator, 4,4'-azobis(cyanovaleric acid). This ensured that the formation of the MIP thin film, comprising 2-(diethylamino) ethyl methacrylate as functional monomer and ethylene glycol dimethacrylate as cross-linker, occurred only at the surface level. Optimisation and control over the grafting procedure were achieved using contact angle measurements and atomic force microscope (AFM) imaging. The surface grafting resulted in the formation of thin and homogeneous MIP film with thickness of 40 nm. A competitive binding assay was performed with free DA and its conjugate with horseradish peroxidase, which was used as a refractive label. The sensor was evaluated for its sensitivity, cross-reactivity, and robustness by using a BIAcore 3000. Likewise, monoclonal antibodies acting as natural receptors for the toxin were studied with the same BIAcore system. Results of a comparison between the artificial and natural receptors are reported. In contrast to monoclonal antibodies, the regeneration of MIP chip did not affect its recognition properties and continuous measurement was possible over a period of at least 2 months.

  11. Preparation, characterization and selective recognition for vanillic acid imprinted mesoporous silica polymers

    NASA Astrophysics Data System (ADS)

    Li, Hui; Xu, Miaomiao; Wang, Susu; Lu, Cuimei; Li, Zhiping

    2015-02-01

    A vanillic acid imprinted mesoporous silica polymer (MIPs) was prepared by copolymerizing a modified mesoporous silica molecular sieve with template molecule, functional monomer and cross-linker in present work. Interaction between the template and functional monomer was investigated by ultraviolet/visible spectrophotometry. These MIPs were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption dynamics and thermodynamic behavior of MIPs was explored and the selective recognition capability evaluated. Also, the applicability for the MIPs as solid phase extraction media was tested. Results indicated the 1:1 (mole ratio) complex of vanillic acid-4-vinylpyridine might predominate in the pre-polymerization mixture and the MIPs obtained possessed rapid binding dynamics and higher affinity toward template molecules, reaching adsorption equilibrium within 230 min with the highest adsorption amount of 50.7 mg g-1. Freundlich model was shown best to describe isotherm adsorption for the MIPs. The MIPs could selectively bind template molecule with selectivity coefficients of 1.36-1.50. In addition, a higher enrichment capability when using it for gathering target compound from methanol extract of Artemisia stelleriana and a good reusability during adsorption-desorption recycling use could be observed.

  12. Photo-initiated grafting of gelatin/N-maleic acyl-chitosan to enhance endothelial cell adhesion, proliferation and function on PLA surface.

    PubMed

    Zhu, Aiping; Zhao, Feng; Ma, Teng

    2009-07-01

    Vascular graft surface properties significantly affect adhesion, growth and function of endothelial cells (ECs). The bulk degradation property of poly(lactic acid) (PLA) makes it possible for it to be replaced by cellular materials and PLA is desirable as a scaffold material for vascular grafts. However, PLA has an unfavorable surface property for EC adhesion and proliferation due to the lack of a selective cell adhesion motif. Photo-initiated surface-grafting polymerization is a promising method for immobilizing certain biomacromolecules on material surfaces without compromising bulk properties. N-Maleic acyl-chitosan (NMCS) is a novel biocompatible amphiphilic derivative of chitosan with double bonds and can be initiated by ultraviolet light. In this study, gelatin was complexed with NMCS via hydrophobic interaction, and gel/NMCS complex thus formed was then grafted on the PLA surface to improve EC biocompatibility. X-ray photoelectron and Fourier transform infrared spectroscopy, and water contact angle measurement confirmed immobilization of the gel/NMCS complex on PLA surface. Moreover, the gel/NMCS modified PLA enhanced human umbilical vein endothelial cell (HUVEC) spreading and flattening, and promoted the expression of more structured CD31 and vWF compared to unmodified PLA film. Compared to the unmodified PLA surface, the HUVECs on the modified PLA surface had elevated uptake of acetylated low-density lipoprotein, and maintained the ability to modulate metabolic activity upon exposure to shear stress at 5dyncm(-2) by up-regulating nitric oxide and prostacyclin production. Cell retention was 1.6 times higher on the gel/NMCS-PLA surface, demonstrating its improved potential for hemocompatibility. These results indicate that photo-initiated surface-grafting of the biomimetic gel/NMCS complex is an effective method to modify material surfaces as vascular grafts.

  13. Membrane protein extraction and purification using styrene-maleic acid (SMA) copolymer: effect of variations in polymer structure.

    PubMed

    Morrison, Kerrie A; Akram, Aneel; Mathews, Ashlyn; Khan, Zoeya A; Patel, Jaimin H; Zhou, Chumin; Hardy, David J; Moore-Kelly, Charles; Patel, Roshani; Odiba, Victor; Knowles, Tim J; Javed, Masood-Ul-Hassan; Chmel, Nikola P; Dafforn, Timothy R; Rothnie, Alice J

    2016-12-01

    The use of styrene-maleic acid (SMA) copolymers to extract and purify transmembrane proteins, while retaining their native bilayer environment, overcomes many of the disadvantages associated with conventional detergent-based procedures. This approach has huge potential for the future of membrane protein structural and functional studies. In this investigation, we have systematically tested a range of commercially available SMA polymers, varying in both the ratio of styrene and maleic acid and in total size, for the ability to extract, purify and stabilise transmembrane proteins. Three different membrane proteins (BmrA, LeuT and ZipA), which vary in size and shape, were used. Our results show that several polymers, can be used to extract membrane proteins, comparably to conventional detergents. A styrene:maleic acid ratio of either 2:1 or 3:1, combined with a relatively small average molecular mass (7.5-10 kDa), is optimal for membrane extraction, and this appears to be independent of the protein size, shape or expression system. A subset of polymers were taken forward for purification, functional and stability tests. Following a one-step affinity purification, SMA 2000 was found to be the best choice for yield, purity and function. However, the other polymers offer subtle differences in size and sensitivity to divalent cations that may be useful for a variety of downstream applications.

  14. Biased versus unbiased randomness in homo-polymers and copolymers of amino acids in the prebiotic world.

    PubMed

    Mosqueira, Fernando G; Negron, Alicia; Ramos, Sergio; Polanco, Carlos

    2012-01-01

    The polymerization of amino acids under anhydrous prebiotic conditions was first studied several decades ago. Here we use a stochastic model stressing the relevant role of the polarity of amino acids in the formation of oligopeptides in a prebiotic milieu. Our goal is to outline the predominance of co-polypeptides over homo-polypeptides, resulting not only from the randomness, but also from polarity properties of amino acids. Our results conclude that there was a higher probability of the formation of co-polypeptides than of homo-polymers. Besides, we may hypothesize that the former would have a more ample spectrum of possible chemical functions than homo-polypeptides.

  15. Biodegradation of high molecular weight polylactic acid

    NASA Astrophysics Data System (ADS)

    Stloukal, Petr; Koutny, Marek; Sedlarik, Vladimir; Kucharczyk, Pavel

    2012-07-01

    Polylactid acid seems to be an appropriate replacement of conventional non-biodegradable synthetic polymer primarily due to comparable mechanical, thermal and processing properties in its high molecular weight form. Biodegradation of high molecular PLA was studied in compost for various forms differing in their specific surface area. The material proved its good biodegradability under composting conditions and all investigated forms showed to be acceptable for industrial composting. Despite expectations, no significant differences in resulting mineralizations were observed for fiber, film and powder sample forms with different specific surface areas. The clearly faster biodegradation was detected only for the thin coating on porous material with high specific surface area.

  16. Moleculary imprinted polymers with metalloporphyrin-based molecular recognition sites coassembled with methacrylic acid.

    PubMed

    Takeuchi, T; Mukawa, T; Matsui, J; Higashi, M; Shimizu, K D

    2001-08-15

    A diastereoselective molecularly imprinted polymer (MIP) for (-)-cinchonidine, PPM(CD), was prepared by the combined use of methacrylic acid and vinyl-substituted zinc(II) porphyrin as functional monomers. Compared to MIPs using only methacrylic acid or zinc porphyrin as a functional monomer, PM(CD) and PP(CD), respectively, PPM(CD) showed higher binding ability for (-)-cinchonidine in chromatographic tests using the MIP-packed columns. Scatchard analysis gave a higher association constant of PPM(CD) for (-)-cinchonidine (1.14 x 10(7) M(-1)) than those of PP(CD) (1.45 x 10(6) M(-1)) and PM(CD) (6.78 x 10(6) M(-1)). The affinity distribution of binding sites estimated by affinity spectrum analysis showed a higher percentage of high-affinity sites and a lower percentage of low-affinity sites in PPM(CD). The MIPs containing a zinc(II) porphyrin in the binding sites, PPM(CD) and PP(CD), showed fluorescence quenching according to the binding of (-)-cinchonidine, and the quenching was significant in the low-concentration range, suggesting that the high-affinity binding sites contain the porphyrin residue. The correlation of the relative fluorescence intensity against log of (-)-cinchonidine concentrations showed a linear relationship. These results revealed that the MIP having highly specific binding sites was assembled by the two functional monomers, vinyl-substituted zinc(II) porphyrin and methacrylic acid, and they cooperatively worked to yield the specific binding. In addition, the zinc(II) porphyrin-based MIPs appeared to act as fluorescence sensor selectively responded by binding events of the template molecule.

  17. PLA coated paper containing active inorganic nanoparticles: Material characterization and fate of nanoparticles in the paper recycling process.

    PubMed

    Zhang, Hai; Bussini, Daniele; Hortal, Mercedes; Elegir, Graziano; Mendes, Joana; Jordá Beneyto, Maria

    2016-06-01

    For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality.

  18. Polybiguanide (PHMB) loaded in PLA scaffolds displaying high hydrophobic, biocompatibility and antibacterial properties.

    PubMed

    Llorens, Elena; Calderón, Silvia; del Valle, Luis J; Puiggalí, Jordi

    2015-05-01

    Polyhexamethylenebiguanide hydrochloride (PHMB), a low molecular weight polymer related to chlorohexidine (CHX), is a well-known antibacterial agent. In this study, polylactide (PLA) nanofibers loaded with PHMB were produced by electrospinning to obtain 3D biodegradable scaffolds with antibacterial properties. PLA fibers loaded with CHX were used as control. The electrospun fibers were studied and analyzed by SEM, FTIR, DSC and contact angle measurements. PHMB and CHX release from loaded scaffolds was evaluated, as well as their antibacterial activity and biocompatibility. The results showed that the nanofibers became smoother and their diameter smaller with increasing the amount of loaded PHMB. This feature led to an increase of both surface roughness and hydrophobicity of the scaffold. PHMB release was highly dependent on the hydrophilicity of the medium and differed from that determined for CHX. Lastly, PHMB-loaded PLA scaffolds showed antibacterial properties since they inhibited adhesion and bacterial growth, and exhibited biocompatible characteristics for the adhesion and proliferation of both fibroblast and epithelial cell lines.

  19. Improving the compressive strength of bioceramic robocast scaffolds by polymer infiltration.

    PubMed

    Martínez-Vázquez, Francisco J; Perera, Fidel H; Miranda, Pedro; Pajares, Antonia; Guiberteau, Fernando

    2010-11-01

    The effect of polymer infiltration on the compressive strength of β-tricalcium phosphate (TCP) scaffolds fabricated by robocasting (direct write assembly) is analyzed in this work. Porous structures consisting of a tetragonal three-dimensional mesh of interpenetrating rods were fabricated from concentrated TCP inks with suitable viscoelastic properties. Biodegradable polymers (polylactic acid (PLA) and poly(ε-caprolactone) (PCL)) were infiltrated into selected scaffolds by immersion of the structure in a polymer melt. Infiltration increased the uniaxial compressive strength of these model scaffolds by a factor of three (PCL) or six (PLA). It also considerably improved the mechanical integrity of the structures after initial cracking, with the infiltrated structure retaining a significant load-bearing capacity after fracture of the ceramic rods. The strength improvement in the infiltrated scaffolds was attributed to two different contributions: the sealing of precursor flaws in the ceramic rod surfaces and the partial transfer of stress to the polymer, as confirmed by finite element analysis. The implications of these results for the mechanical optimization of scaffolds for bone tissue engineering applications are discussed.

  20. Mice deficient in Group VIB phospholipase A2 (iPLA2γ) exhibit relative resistance to obesity and metabolic abnormalities induced by a Western diet

    PubMed Central

    Song, Haowei; Wohltmann, Mary; Bao, Shunzhong; Ladenson, Jack H.; Semenkovich, Clay F.

    2010-01-01

    Phospholipases A2 (PLA2) play important roles in metabolic processes, and the Group VI PLA2 family is comprised of intracellular enzymes that do not require Ca2+ for catalysis. Mice deficient in Group VIA PLA2 (iPLA2β) develop more severe glucose intolerance than wild-type (WT) mice in response to dietary stress. Group VIB PLA2 (iPLA2γ) is a related enzyme distributed in membranous organelles, including mitochondria, and iPLA2γ knockout (KO) mice exhibit altered mitochondrial morphology and function. We have compared metabolic responses of iPLA2γ-KO and WT mice fed a Western diet (WD) with a high fat content. We find that KO mice are resistant to WD-induced increases in body weight and adiposity and in blood levels of cholesterol, glucose, and insulin, even though WT and KO mice exhibit similar food consumption and dietary fat digestion and absorption. KO mice are also relatively resistant to WD-induced insulin resistance, glucose intolerance, and altered patterns of fat vs. carbohydrate fuel utilization. KO skeletal muscle exhibits impaired mitochondrial β-oxidation of fatty acids, as reflected by accumulation of larger amounts of long-chain acylcarnitine (LCAC) species in KO muscle and liver compared with WT in response to WD feeding. This is associated with increased urinary excretion of LCAC and much reduced deposition of triacylglycerols in liver by WD-fed KO compared with WT mice. The iPLA2γ-deficient genotype thus results in a phenotype characterized by impaired mitochondrial oxidation of fatty acids and relative resistance to the metabolic abnormalities induced by WD. PMID:20179248

  1. iPLA2β deficiency attenuates obesity and hepatic steatosis in ob/ob mice through hepatic fatty-acyl phospholipid remodeling.

    PubMed

    Deng, Xiuling; Wang, Jiliang; Jiao, Li; Utaipan, Tanyarath; Tuma-Kellner, Sabine; Schmitz, Gerd; Liebisch, Gerhard; Stremmel, Wolfgang; Chamulitrat, Walee

    2016-05-01

    PLA2G6 or GVIA calcium-independent PLA2 (iPLA2β) is identified as one of the NAFLD modifier genes in humans, and thought to be a target for NAFLD therapy. iPLA2β is known to play a house-keeping role in phospholipid metabolism and remodeling. However, its role in NAFLD pathogenesis has not been supported by results obtained from high-fat feeding of iPLA2β-null (PKO) mice. Unlike livers of human NAFLD and genetically obese rodents, fatty liver induced by high-fat diet is not associated with depletion of hepatic phospholipids. We therefore tested whether iPLA2β could regulate obesity and hepatic steatosis in leptin-deficient mice by cross-breeding PKO with ob/ob mice to generate ob/ob-PKO mice. Here we observed an improvement in ob/ob-PKO mice with significant reduction in serum enzymes, lipids, glucose, insulin as well as improved glucose tolerance, and reduction in islet hyperplasia. The improvement in hepatic steatosis measured by liver triglycerides, fatty acids and cholesterol esters was associated with decreased expression of PPARγ and de novo lipogenesis genes, and the reversal of β-oxidation gene expression. Notably, ob/ob livers contained depleted levels of lysophospholipids and phospholipids, and iPLA2β deficiency in ob/ob-PKO livers lowers the former, but replenished the latter particularly phosphatidylethanolamine (PE) and phosphatidylcholine (PC) that contained arachidonic (AA) and docosahexaenoic (DHA) acids. Compared with WT livers, PKO livers also contained increased PE and PC containing AA and DHA. Thus, iPLA2β deficiency protected against obesity and ob/ob fatty liver which was associated with hepatic fatty-acyl phospholipid remodeling. Our results support the deleterious role of iPLA2β in severe obesity associated NAFLD.

  2. Comparison of the sensitive property between soman and its simulant DMMP by hydrogen-bond acidic polymer coated SAW sensor

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Du, Xiaosong; Long, Yin; Jiang, Yadong

    2014-08-01

    Hydrogen-bond acidic (HBA) polymers are widely used for the detection of dimethyl methyl phosphonate (DMMP, a simulant of real nerve agents) based on surface acoustic wave (SAW) sensors. This paper presented an HBA polymer PLF, and subsequently the polymer was dissolved into chloroform and spray-coated on a SAW device to fabricate a gas sensor. Then the sensor was equipped into a SAW test platform to investigate its sensitive property to soman vapor and its simulant DMMP at the concentrations below 20 mg/m3. Results revealed that the sensor showed high sensitivity to the analyte vapors, furthermore, the response of the sensor to soman vapor was relatively smaller and slower than that to DMMP. Tests to some common interference vapors were studied at the concentration of 10 mg/m3, and the results indicated that the sensor showed a good selective property.

  3. The impact of extraction with a chelating agent under acidic conditions on the cell wall polymers of mango peel.

    PubMed

    Jamsazzadeh Kermani, Zahra; Shpigelman, Avi; Kyomugasho, Clare; Van Buggenhout, Sandy; Ramezani, Mohsen; Van Loey, Ann M; Hendrickx, Marc E

    2014-10-15

    The objective of this research was to evaluate whether mango peel is a potential source of functional cell wall polymers. To reach this objective, the native pectin polymers (NPP) extracted as alcohol insoluble residue from mango peel, were characterised in terms of uronic acid content, degree of methoxylation, neutral sugar content, and molar mass and compared to citric acid (pH 2.5, 2h at 80°C) extracted polymers, mimicking industrial pectin extraction conditions. Water-solubilised NPP were highly methoxylated having two populations with a Mw of 904 and 83kDa and a degree of methoxylation of 66%. Citric acid extraction with a yield higher than H2SO4 extraction resulted in a very branched pectin with an extremely high DM (83%) and a high molar mass. Comparing the Fourier Transform Infra-Red spectroscopy of extracted and native WSF showed that citric acid remained partially associated to the extracted pectin due to its chelating properties.

  4. Fabrication of enzyme reactor utilizing magnetic porous polymer membrane for screening D-Amino acid oxidase inhibitors.

    PubMed

    Jiang, Jun Fang; Qiao, Juan; Mu, Xiao Yu; Moon, Myeong Hee; Qi, Li

    2017-04-01

    In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined (Km was 1.10mM, Vmax was 23.8mMmin(-1)) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors.

  5. Biocompatibility and characterization of polylactic acid/styrene-ethylene-butylene-styrene composites.

    PubMed

    Tsou, Chi-Hui; Kao, Bo-Jyue; Yang, Ming-Chien; Suen, Maw-Cherng; Lee, Yi-Hsuan; Chen, Jui-Chin; Yao, Wei-Hua; Lin, Shang-Ming; Tsou, Chih-Yuan; Huang, Shu-Hsien; De Guzman, Manuel; Hung, Wei-Song

    2015-01-01

    Polylactic acid (PLA)/styrene-ethylene-butylene-styrene (SEBS) composites were prepared by melt blending. Differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WXRD) were used to characterize PLA and PLA/SEBS composites in terms of their melting behavior and crystallization. Curves from thermal gravimetric analysis (TGA) illustrated that thermostability increased with SEBS content. Further morphological analysis of PLA/SEBS composites revealed that SEBS molecules were not miscible with PLA molecules in PLA/SEBS composites. The tensile testing for PLA and PLA/SEBS composites showed that the elongation at the break was enhanced, but tensile strength decreased with increasing SEBS content. L929 fibroblast cells were chosen to assess the cytocompatibility; the cell growth of PLA was found to decrease with increasing SEBS content. This study proposes possible reasons for these properties of PLA/SEBS composites.

  6. Chiral resolution of derivatized amino acids using uniformly sized molecularly imprinted polymers in hydro-organic mobile phases.

    PubMed

    Haginaka, Jun; Kagawa, Chino

    2004-04-01

    Uniformly sized molecularly imprinted polymers (MIPs) for Boc-L-Trp were prepared using ethylene glycol dimethacrylate (EDMA) as the cross-linker, and methacylic acid (MAA) and/or 4-vinylpyridine (4-VPY) as the functional monomers or without use of a functional monomer. The MIPs prepared were evaluated using acetonitrile or a mixture of phosphate buffer and acetonitrile as the mobile phase. The Boc-L-Trp-imprinted EDMA polymers can recognize Boc-L-Trp by its molecular shape, and can thus afford the enantioseparation of Boc-Trp. Besides the molecular shape recognition, the hydrophobic interactions with the polymer backbones as well as the hydrogen-bonding interactions of Boc-L-Trp with carboxyl and pyridyl groups in the polymers should work for the retention and recognition of Boc-L-Trp on the imprinted MAA- co-EDMA and 4-VPY- co-EDMA polymers, respectively, in the hydro-organic mobile phase. The hydrogen-bonding interactions seem to become dominant when only acetonitrile is used as the mobile phase. The Boc-L-Trp-imprinted 4-VPY- co-EDMA polymers gave the highest retentivity and enantioselectivity for Boc-Trp among the MIPs prepared. However, the simultaneous use of MAA and 4-VPY was not effective for the enantioseparation of Boc-Trp in a hydro-organic mobile phase. Furthermore, the baseline separation of Boc-Trp enantiomers was attained within 10 min on the Boc-L-Trp-imprinted 4-VPY- co-EDMA polymers under the optimized HPLC conditions.

  7. Electropolymerized molecularly imprinted polymer films of a bis-terthiophene dendron: folic acid quartz crystal microbalance sensing.

    PubMed

    Apodaca, Dahlia C; Pernites, Roderick B; Ponnapati, Ramakrishna R; Del Mundo, Florian R; Advincula, Rigoberto C

    2011-02-01

    A folic acid sensor was prepared via an electropolymerized molecularly imprinted polymer (E-MIP) film of a bis-terthiophene dendron on a quartz crystal microbalance (QCM). The cyclic voltammetry (CV) electrodeposition of the imprinted polymer film was monitored by electrochemical QCM or E-QCM, enabling in situ monitoring and characterization of E-MIP film formation and the viscoelastic behavior of the film. A key component of the E-MIP process is the use of a bifunctional monomer design to precomplex with the template and function as a cross-linker. The complex was electropolymerized and cross-linked by CV to form a polythiophene matrix. Stable cavities were formed that specifically fit the size and shape of the folic acid template. The same substrate surface was used for folic acid sensing. The predicted geometry of the 1:2 folic acid/terthiophene complex was obtained through semiempirical AM1 quantum calculations. The analytical performance, expressed through the figures of merit, of the sensor in aqueous solutions of the analyte was investigated. A relatively good linearity, R(2) = 0.985, was obtained within the concentration range 0-100 μM folic acid. The detection limit was found to be equal to 15.4 μM (6.8 μg). The relative cross selectivity of the folic acid imprinted polymer against the three molecules follows this trend: pteroic acid (= 50%) > caffeine (= 41%) > theophylline (= 6%). The potential and limitations of the E-MIP method were also discussed.

  8. Modulated in Vitro Biocompatibility of a Unique Cross-Linked Salicylic Acid-Poly(ε-caprolactone)-Based Biodegradable Polymer.

    PubMed

    Bhaskar, Nitu; Padmavathy, Nagarajan; Jain, Shubham; Bose, Suryasarathi; Basu, Bikramjit

    2016-11-02

    Herein, we report the development of a unique architecture by chemically cross-linking salicylic acid (SA)-based poly(anhydride ester) onto a biodegradable amine-functionalized poly(caprolactone) (PCL), using lactic acid as a spacer. The ester and amide linkages in the SA-PCL polymer, synthesized through melt condensation, were confirmed by NMR and FT-IR spectroscopic techniques. The enzymatic and nonenzymatic hydrolytic degradation profile exhibited linear degradation kinetics over an extended time period (>5 weeks). The compatibility and growth of C2C12 myoblast cells were found to be significantly improved on the fast-degrading SA-PCL substrates compared to those over neat PCL and amine-functionalized PCL. Further, the decreased red blood cell damage, illustrated by 0.39% hemolysis activity and a minimal number of platelet adhesion on a SA-PCL polymeric surface confirmed good hemocompatibility of the as-synthesized polymer. Together with a moderate bactericidal property, the spectrum of properties of this novel polymer can be attributed to the synergistic effect of the presence of chemical moieties of SA and amine groups in PCL. In summary, it is considered that a SA-PCL-based cross-linked composite can be utilized as a new biodegradable polymer.

  9. The Chemical Behavior and Degradation Mitigation Effect of Cerium Oxide Nanoparticles in Perfluorosulfonic Acid Polymer Electrolyte Membranes

    SciTech Connect

    Pearman, Benjamin P; Mohajeri, Nahid; Slattery, Darlene; Hampton, Michael; Seal, Sudipta; Cullen, David A

    2013-01-01

    Perfluorosulfonic acid membranes, the polymer of choice for polymer electrolyte hydrogen fuel cells, are susceptible to degradation due to attacks on polymer chains from radicals. Mitigation of this attack by cerium-based radical scavengers is an approach that has shown promise. In this work, two formulations of single-crystal cerium oxide nanoparticles, with an order of magnitude difference in particle size, are incorporated into said membranes and subjected to proton conductivity measurements and ex-situ durability tests. We found that ceria is reduced to Ce(III) ions in the acidic environment of a heated, humidified membrane which negatively impacts proton conductivity. In liquid and gas Fenton testing, fluoride emission is reduced by an order of magnitude, drastically increasing membrane longevity. Side-product analysis demonstrated that in the liquid Fenton test, the main point of attack are weak polymer end groups, while in the gas Fenton test, there is additional side-chain attack. Both mechanisms are mitigated by the addition of the ceria nanoparticles, whereby the extent of the durability improvement is found to be independent of particle size.

  10. Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy.

    PubMed

    Eberhardt, S H; Marone, F; Stampanoni, M; Büchi, F N; Schmidt, T J

    2014-11-01

    Synchrotron-based X-ray tomographic microscopy is investigated for imaging the local distribution and concentration of phosphoric acid in high-temperature polymer electrolyte fuel cells. Phosphoric acid fills the pores of the macro- and microporous fuel cell components. Its concentration in the fuel cell varies over a wide range (40-100 wt% H3PO4). This renders the quantification and concentration determination challenging. The problem is solved by using propagation-based phase contrast imaging and a referencing method. Fuel cell components with known acid concentrations were used to correlate greyscale values and acid concentrations. Thus calibration curves were established for the gas diffusion layer, catalyst layer and membrane in a non-operating fuel cell. The non-destructive imaging methodology was verified by comparing image-based values for acid content and concentration in the gas diffusion layer with those from chemical analysis.

  11. Biomedical nanocomposites of poly(lactic acid) and calcium phosphate hybridized with modified carbon nanotubes for hard tissue implants.

    PubMed

    Lee, Hae-Hyoung; Sang Shin, Ueon; Lee, Jae-Ho; Kim, Hae-Won

    2011-08-01

    Degradable polymer-based materials are attractive in orthopedics and dentistry as an alternative to metallic implants for use as bone fixatives. Herein, a degradable polymer poly(lactic acid) (PLA) was combined with novel hybrid nanopowder of carbon nanotubes (CNTs)-calcium phosphate (CP) for this application. In particular, CNTs-CP hybrid nanopowders (0.1 and 0.25% CNTs) were prepared from the solution of ionically modified CNTs (mCNTs), which was specifically synthesized to be well-dispersed and thus to effectively adsorb onto the CP nanoparticles. The mCNTs-CP hybrid nanopowders were then mixed with PLA (up to 50%) to produce mCNTs-CP-PLA nanocomposites. The mechanical tensile strength of the nanocomposites was significantly improved by the addition of mCNTs-CP hybrid nanopowders. Moreover, nanocomposites containing low concentration of mCNTs (0.1%) showed significantly stimulated biological responses including cell proliferation and osteoblastic differentiation in terms of gene and protein expressions. Based on this study, the addition of novel mCNT-CP hybrid nanopowders to PLA biopolymer may be considered a new material choice for developing hard tissue implants.

  12. Effect of phosphate-based glass fibre surface properties on thermally produced poly(lactic acid) matrix composites.

    PubMed

    Mohammadi, Maziar Shah; Ahmed, Ifty; Muja, Naser; Rudd, Christopher D; Bureau, Martin N; Nazhat, Showan N

    2011-12-01

    Incorporation of soluble bioactive glass fibres into biodegradable polymers is an interesting approach for bone repair and regeneration. However, the glass composition and its surface properties significantly affect the nature of the fibre-matrix interface and composite properties. Herein, the effect of Si and Fe on the surface properties of calcium containing phosphate based glasses (PGs) in the system (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x = 0, 5 and 10 mol.%) were investigated. Contact angle measurements revealed a higher surface energy, and surface polarity as well as increased hydrophilicity for Si doped PG which may account for the presence of surface hydroxyl groups. Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibres and randomly incorporated into poly(lactic acid) (PLA) produced by melt processing. The ageing in deionised water (DW), mechanical property changes in phosphate buffered saline (PBS) and cytocompatibility properties of these composites were investigated. In contrast to Fe10 and as a consequence of the higher surface energy and polarity of Fe5Si5, its incorporation into PLA led to increased inorganic/organic interaction indicated by a reduction in the carbonyl group of the matrix. PLA chain scission was confirmed by a greater reduction in its molecular weight in PLA-Fe5Si5 composites. In DW, the dissolution rate of PLA-Fe5Si5 was significantly higher than that of PLA-Fe10. Dissolution of the glass fibres resulted in the formation of channels within the matrix. Initial flexural strength was significantly increased through PGF incorporation. After PBS ageing, the reduction in mechanical properties was greater for PLA-Fe5Si5 compared to PLA-Fe10. MC3T3-E1 preosteoblasts seeded onto PG discs, PLA and PLA-PGF composites were evaluated for up to 7 days indicating that the materials were generally cytocompatible. In addition, cell alignment along the PGF

  13. Simulation of mechanical behavior and optimization of simulated injection molding process for PLA based antibacterial composite and nanocomposite bone screws using central composite design.

    PubMed

    Heidari, Behzad Shiroud; Oliaei, Erfan; Shayesteh, Hadi; Davachi, Seyed Mohammad; Hejazi, Iman; Seyfi, Javad; Bahrami, Mozhgan; Rashedi, Hamid

    2017-01-01

    In this study, injection molding of three poly lactic acid (PLA) based bone screws was simulated and optimized through minimizing the shrinkage and warpage of the bone screws. The optimization was carried out by investigating the process factors such as coolant temperature, mold temperature, melt temperature, packing time, injection time, and packing pressure. A response surface methodology (RSM), based on the central composite design (CCD), was used to determine the effects of the process factors on the PLA based bone screws. Upon applying the method of maximizing the desirability function, optimization of the factors gave the lowest warpage and shrinkage for nanocomposite PLA bone screw (PLA9). Moreover, PLA9 has the greatest desirability among the selected materials for bone screw injection molding. Meanwhile, a finite element analysis (FE analysis) was also performed to determine the force values and concentration points which cause yielding of the screws under certain conditions. The Von-Mises stress distribution showed that PLA9 screw is more resistant against the highest loads as compared to the other ones. Finally, according to the results of injection molding simulations, the design of experiments (DOE) and structural analysis, PLA9 screw is recommended as the best candidate for the production of biomedical materials among all the three types of screws.

  14. Molecular modeling of the inhibition of enzyme PLA2 from snake venom by dipyrone and 1-phenyl-3-methyl-5-pyrazolone

    NASA Astrophysics Data System (ADS)

    Silva, S. L. Da; Comar, M., Jr.; Oliveira, K. M. T.; Chaar, J. S.; Bezerra, E. R. M.; Calgarotto, A. K.; Baldasso, P. A.; Veber, C. L.; Villar, J. A. F. P.; Oliveira, A. R. M.; Marangoni, S.

    Phospholipases A2 (PLA2) are enzymes that trigger the degradation cascade of the arachidonic acid, leading to the formation of pro-inflammatory eicosanoids. The selective inhibition of PLA2s is crucial in the search for a more efficient anti-inflammatory drug with fewer side effects than the drugs currently used. Hence, we studied the influences caused by two pyrazolonic inhibitors: dipyrone (DIP) and 1-phenyl-3-methyl-5-pyrazolone (PMP) on the kinetic behavior of PLA2 from Crotalus adamanteus venom. Molecular modeling results, by DFT and MM approaches, showed that DIP is strongly associated to the active site of PLA2 through three hydrogen bonds, whereas PMP is associated to the enzyme just through hydrophobic interactions. In addition, only PMP presents an intramolecular hydrogen bond that make difficult the formation of more efficient interactions with PLA2. These results help in the understanding of the experimental observations. Experimentally, the results showed that PLA2 from C. adamanteus present a typical Michaelian behavior. In addition, the calculated kinetic parameters showed that, in the presence of DIP or PMP, the maximum enzymatic velocity (VMAX) value was kept constant, whereas the Michaelis constant (KM) values increased and the inhibition constant (KI) decreased, indicating competitive inhibition. These results show that the phenyl-pyrazolonic structures might help in the development and design of new drugs able to selectively inhibit PLA2.

  15. Relevance of nonfunctional linear polyacrylic acid for the biodegradation of superabsorbent polymer in soils.

    PubMed

    Bai, Mo; Wilske, Burkhard; Buegger, Franz; Esperschütz, Jürgen; Bach, Martin; Frede, Hans-Georg; Breuer, Lutz

    2015-04-01

    Biodegradability is a desired characteristic for synthetic soil amendments. Cross-linked polyacrylic acid (PAA) is a synthetic superabsorbent used to increase the water availability for plant growth in soils. About 4% within products of cross-linked PAA remains as linear polyacrylic acid (PAAlinear). PAAlinear has no superabsorbent function but may contribute to the apparent biodegradation of the overall product. This is the first study that shows specifically the biodegradation of PAAlinear in agricultural soil. Two (13)C-labeled PAAlinear of the average molecular weights of 530, 400, and 219,500 g mol(-1) were incubated in soil. Mineralization of PAAlinear was measured directly as the (13)CO2 efflux from incubation vessels using an automatic system, which is based on (13)C-sensitive wavelength-scanned cavity ring-down spectroscopy. After 149 days, the PAAlinear with the larger average molecular weight and chain length showed about half of the degradation (0.91% of the initial weight) of the smaller PAAlinear (1.85%). The difference in biodegradation was confirmed by the δ(13)C signature of the microbial biomass (δ(13)Cmic), which was significantly enriched in the samples with short PAAlinear (-13‰ against reference Vienna Pee Dee Belemnite,VPDB) as compared to those with long PAAlinear (-16‰ VPDB). In agreement with other polymer studies, the results suggest that the biodegradation of PAAlinear in soil is determined by the average molecular weight and occurs mainly at terminal sites. Most importantly, the study outlines that the size of PAA that escapes cross-linking can have a significant impact on the overall biodegradability of a PAA-based superabsorbent.

  16. New multifunctional pharmaceutical excipient in tablet formulation based on citric acid-cyclodextrin polymer.

    PubMed

    Garcia-Fernandez, Maria José; Tabary, Nicolas; Chai, Feng; Cazaux, Frédéric; Blanchemain, Nicolas; Flament, Marie-Pierre; Martel, Bernard

    2016-09-25

    A β-cyclodextrin (β-CD) polymer obtained by crosslinking β-CD with citric acid in its water-insoluble (PCD-I) and soluble (PCD-S) forms was used as a multifunctional direct compression excipient for tablet designing. PCD-I powder was obtained after grinding the solid fraction through a 200μm grid. PCD-S powder was recovered after lyophilization or spray drying of the PCD-S aqueous solutions, eventually followed by a wet granulation step. Both PCD-I and PCD-S powders were characterized, separately and mixed in variable ratios, based on dynamic water vapor sorption, SEM, particle size distribution, tapped density, compressibility, and flowability. PCD-I and spray dried and lyophilized/wet granulated PCD-S, as well as the mixture PCD-I/PCD-S=90/10, presented optimal free flowing characteristics. Then, PCD-I or PCD-S powders - separately or mixed in variable ratios - were used for tablets preparation by direct compression without adding any other excipient (e.g. binder, lubricant, disintegrant etc). As PCD-I decreased, tablets resistance to crushing and disintegration time increased from 15s to 15min (against 30min for β-CD), showing the improved disintegrant functionality of PCD-I, that rapidly swelled once in contact with water. Finally, PCD was force-fed to Sprague-Dawley rats (2g/kg) which were then observed during 14days for any clinical signs of toxicity.

  17. Novel polymer-graphite composite grid as a negative current collector for lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Shukai; Zhang, Hao; Cheng, Jie; Zhang, Wenfeng; Cao, Gaoping; Zhao, Hailei; Yang, Yusheng

    2016-12-01

    We design a novel polymer-graphite composite grid as the negative current collector for lead-acid batteries. With this novel grid, the negative active material (NAM) can deliver a specific capacity of 170 mAh g-1 at a discharge rate of 0.1 C. After that, we conduct structural optimization and surface treatment on the grid to improve its performance. Through the structural optimization, additional lead pastes can be loaded and the cycle stability of the battery is enhanced. By using the optimized grid, the weight of the negative current collector can be remarkably reduced by more than 50%. To handle the serious hydrogen evolution on the graphite surface and the unfavorable adhesion between graphite and NAM, fine PbSO4 particles are coated onto the surface of the graphite grids by chemical deposition. The cells employing the PbSO4-deposition grids exhibit excellent cycling stability as well as low polarization and then high Coulombic efficiency. We present here a possible mechanism that how PbSO4 deposits effectively enhance the performance of negative plates based on the testing results.

  18. Acid-degradable hyperbranched polymer and its application in bottom anti-reflective coatings

    NASA Astrophysics Data System (ADS)

    Mercado, Ramil-Marcelo L.; Xu, Hao; Lowes, Joyce A.; Meador, Jim D.; Guerrero, Douglas J.

    2008-11-01

    A photosensitive developer-soluble bottom anti-reflective coating (DBARC) system is described for KrF and ArF lithographic applications. The system contains an acid-degradable branched polymer that is self-crosslinked into a polymeric film after spin coating and baking at high temperature, rendering a solvent-insoluble coating. The DBARC coating is tunable in terms having the appropriate light absorption (k value) and thickness for desirable reflection control. After the exposure of the resist, the DBARC layer decrosslinks into developer-soluble small molecules in the presence of photoacid generator (PAG). Thus the DBARC layer is removed simultaneously with the photoresist in the development process, instead of being etched away in a plasma-etching chamber in the case of traditional BARC layers. The etch budget is significantly improved so that a thin resist can be used for better resolution. Alternatively, the etch step can be omitted in the case of the formation of layers that may be damaged by exposure to plasma.

  19. Performance/design formulation for a solid polymer based acid electrolyte hydrogen/air fuel cell

    NASA Astrophysics Data System (ADS)

    Sandhu, S. S.; Fellner, J. P.

    Mathematical development of preliminary performance/design equations for a hydrogen/air, solid polymer acid electrolyte based fuel cell is presented. The development is based on the principles of transport phenomena, intrinsic electrochemical kinetics, and classical thermodynamics. The developed formulation is intended to quantitatively describe the mass fraction profiles of the chemical species, hydrogen and oxygen, in the cell anode and cathode diffusion and electrocatalytic reaction layers as a function of the distance in the proton transport direction at an axial distance parallel to the cell anode or cathode channel flow. Given the cell geometry, chemical species and charge transport, and intrinsic electrochemical kinetic parameters, the developed formulation can be employed to compute the species local mass fluxes and predict the cell anode and cathode cell overvoltages for a desired geometric current density. The presented single cell performance predictive formulation has also been linked to the formulation needed to predict the performance of a stack of a number of identical PEMFCs connected in series.

  20. Copper(II) coordination polymers derived from triethanolamine and pyromellitic acid for bioinspired mild peroxidative oxidation of cyclohexane.

    PubMed

    Karabach, Yauhen Y; Kirillov, Alexander M; Haukka, Matti; Kopylovich, Maximilian N; Pombeiro, Armando J L

    2008-01-01

    The new inorganic 1D coordination polymer [Cu2(H3tea)2(mu4-pma)]n has been prepared, via self-assembly in aqueous medium, from copper(II) nitrate, triethanolamine (H3tea), pyromellitic acid (H4pma) and lithium hydroxide, and characterized by IR spectroscopy, elemental and single-crystal X-ray diffraction analyses. This compound and the related 2D polymer [Cu2(mu-H2tea)(2){mu3-Na2(H2O)4}(mu6-pma)]n.10nH2O are shown to mimic the alkane partial oxidation activity of the multicopper particulate methane monooxygenase, acting as catalysts precursors for the peroxidative oxidation of cyclohexane into cyclohexanol and cyclohexanone, by hydrogen peroxide (as green oxidant) and at room temperature in acidic MeCN/H2O medium. An overall yield (based on cyclohexane) of 29% has been achieved.

  1. Identification and characterization of novel poly(DL-lactic acid) depolymerases from metagenome.

    PubMed

    Mayumi, Daisuke; Akutsu-Shigeno, Yukie; Uchiyama, Hiroo; Nomura, Nobuhiko; Nakajima-Kambe, Toshiaki

    2008-07-01

    Many poly(lactic acid) (PLA)-degrading microorganisms have been isolated from the natural environment by culture-based methods, but there is no study about unculturable PLA-degrading microorganisms. In this study, we constructed a metagenomic library consisting of the DNA extracted from PLA disks buried in compost. We identified three PLA-degrading genes encoding lipase or hydrolase. The purified enzymes degraded not only PLA, but also various aliphatic polyesters, tributyrin, and p-nitrophenyl esters. From their substrate specificities, the PLA depolymerases were classified into an esterase rather than a lipase. Among the PLA depolymerases, PlaM4 exhibited thermophilic properties; that is, it showed the highest activity at 70 degrees C and was stable even after incubation for 1 h at 50 degrees C. PlaM4 had absorption and degradation activities for solid PLA at 60 degrees C, which indicates that the enzyme can effectively degrade PLA in a high-temperature environment. On the other hand, the enzyme classification based on amino acid sequences showed that the other PLA depolymerases, PlaM7 and PlaM9, were not classified into known lipases or esterases. This is the first report on the identification and characterization of PLA depolymerase from a metagenome.

  2. First high thermally stable organo-inorganic 3D polymer scandium derivative as a heterogeneous Lewis acid catalyst.

    PubMed

    Perles, Josefina; Iglesias, Marta; Ruiz-Valero, Caridad; Snejko, Natalia

    2003-02-07

    Sc2(OOCC2H4COO)2.5(OH), a new hybrid organic-inorganic polymer, has been hydrothermally obtained; the crystal structure of this material has been established by single crystal X-ray diffraction; having high thermal stability it can be used as an effective Lewis acid catalyst and can be easily recycled and reused without any appreciable loss in activity.

  3. Metal-centered polymers: Using controlled polymerization methodologies for the generation of responsive materials

    NASA Astrophysics Data System (ADS)

    Johnson, Robert Matthew

    Controlled polymerization methods were used to prepare highly modular polymeric metal complexes via convergent and divergent strategies. In these materials, the metal center provides a versatile hub for preparing diverse architectures through coordinative bonds. Moreover, the metal complex introduces various properties to the polymer such as luminescence, magnetism, or electroactivity. Suitably functionalized metal complexes have been used for the atom transfer radical polymerization of acrylate and methacrylate monomers by metalloinitiation to generate luminescent biocompatible materials through a divergent synthesis. By cleaving the tert-butyl groups from poly(tert -butyl acrylate), water soluble [Ru(bpyPAA2)3] 2+ has been prepared as well as the amphiphilic star block copolymer [Ru{bpy(PLA-PAA)2}3]2+ (PLA = poly(lactic acid), PAA = poly(acrylic acid) Bipyridine-centered polymeric macroligands may be chelated to a variety of metal salts. The polymer size greatly influences the formation of [Fe(bpy) 3]2+ centered polymers. As the molecular weight increases (> ˜25 kDa) tris complex formation decreases. Tris(bpy) synthesis is also impacted by chemical composition. BpyPtBA2 (PtBA = poly(tert-butyl acrylate) generates an iron mono(bpy) complex before giving rise to the bis(bpy) iron complex; no tris complex is observed. In contrast, the combination of bpyPEG2 (3 equiv) (PEG = (poly(ethylene glycol)) results in the formation of some iron tris(bpy) compound; however, complete tris(bpy) product formation is suppressed, presumably because of the chelating ability of the PEG chains. These examples contrast with other polymeric macroligands such as bpyPS2, bpyPMMA2, bpyPCL2 and bpyPLA 2 (PS = polystyrene; PMMA = poly(methyl methacrylate); PCL = poly(epsilon-caprolactone); PLA = poly(DL-lactic acid)) for which chelation reactions are facile for low molecular weight macroligands (<15 kDa), with chelation efficiencies (defined as (epsilonPMC/epsilonbpy) x 100%) only declining

  4. Activation of mitochondrial calcium-independent phospholipase A2γ (iPLA2γ) by divalent cations mediating arachidonate release and production of downstream eicosanoids.

    PubMed

    Moon, Sung Ho; Jenkins, Christopher M; Liu, Xinping; Guan, Shaoping; Mancuso, David J; Gross, Richard W

    2012-04-27

    Calcium-independent phospholipase A(2)γ (iPLA(2)γ) (PNPLA8) is the predominant phospholipase activity in mammalian mitochondria. However, the chemical mechanisms that regulate its activity are unknown. Here, we utilize iPLA(2)γ gain of function and loss of function genetic models to demonstrate the robust activation of iPLA(2)γ in murine myocardial mitochondria by Ca(2+) or Mg(2+) ions. Calcium ion stimulated the production of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) from 1-palmitoyl-2-[(14)C]arachidonoyl-sn-glycero-3-phosphocholine during incubations with wild-type heart mitochondrial homogenates. Furthermore, incubation of mitochondrial homogenates from transgenic myocardium expressing iPLA(2)γ resulted in 13- and 25-fold increases in the initial rate of radiolabeled 2-AA-LPC and arachidonic acid (AA) production, respectively, in the presence of calcium ion. Mass spectrometric analysis of the products of calcium-activated hydrolysis of endogenous mitochondrial phospholipids in transgenic iPLA(2)γ mitochondria revealed the robust production of AA, 2-AA-LPC, and 2-docosahexaenoyl-LPC that was over 10-fold greater than wild-type mitochondria. The mechanism-based inhibitor (R)-(E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one (BEL) (iPLA(2)γ selective), but not its enantiomer, (S)-BEL (iPLA(2)β selective) or pyrrolidine (cytosolic PLA(2)α selective), markedly attenuated Ca(2+)-dependent fatty acid release and polyunsaturated LPC production. Moreover, Ca(2+)-induced iPLA(2)γ activation was accompanied by the production of downstream eicosanoid metabolites that were nearly completely ablated by (R)-BEL or by genetic ablation of iPLA(2)γ. Intriguingly, Ca(2+)-induced iPLA(2)γ activation was completely inhibited by long-chain acyl-CoA (IC(50) ∼20 μm) as well as by a nonhydrolyzable acyl-CoA thioether analog. Collectively, these results demonstrate that mitochondrial iPLA(2)γ is activated by divalent cations and inhibited by acyl

  5. Hydrophobic-modified nano-cellulose fiber/PLA biodegradable composites for lowering water vapor transmission rate (WVTR) of paper.

    PubMed

    Song, Zhaoping; Xiao, Huining; Zhao, Yi

    2014-10-13

    New biodegradable nanocomposites have been successfully prepared by incorporating modified nano-cellulose fibers (NCF) in a biodegradable polylactic acid (PLA) matrix in this work. The hydrophobic-modified NCF was obtained by grafting hydrophobic monomers on NCF to improve the compatibility between NCF and PLA during blending. The resulting NCF/PLA composites were then applied on paper surface via a cast-coating process in an attempt to reduce the water vapor transmission rate (WVTR) of paper. The WVTR tests, conducted under various testing conditions and with different coating weights, demonstrated that the modified NCF/PLA composites coating played a critical role in lowering WVTR of paper. The lowest WVTR value was 34 g/m(2)/d, which was obtained with an addition of 1% of modified NCF to PLA and the composites coating weight at 40 g/m(2) and substantially lower than the control value at 1315 g/m(2)/d. The paper coated with the modified biodegradable composite is promising as green-based packaging materials.

  6. GS/DBM/PLA porous composite biomaterial for the treatment of infective femoral condyle defect in rats

    PubMed Central

    LIU, XIAOMING; YANG, LIN; LI, JING; ZHANG, YUMING; XU, WEIJUN; REN, YAN; LIU, BIWANG; YANG, BIAO; LI, BAOXING

    2016-01-01

    A bone defect resulting from open bone trauma may easily become infected; however, the administration of efficacious systemic antibiotics cannot be performed at safe levels. Previous studies have investigated anti-infective biomaterials that incorporate into bone and facilitate the direct application of high-concentration local antibiotics. In the present study, the effect of a novel porous composite with gentamicin sulfate (GS) in treating infected femoral condyle defects was investigated using a rat model. A novel porous composite biomaterial was prepared based on a supercritical carbon dioxide fluid technique that combined GS, demineralized bone matrix (DBM) and polylactic acid (PLA). A rat femoral condyle fracture model of infection was established. The GS/DBM/PLA composite biomaterial was implanted and its physicochemical characteristics, biocompatibility and ability to facilitate repair of infected bone defect were assessed. The GS/DBM/PLA composite biomaterial maintained the antibiotic activity of GS, with good anti-compression strength, porosity and biocompatibility. The results of the animal experiments indicated that the GS/DBM/PLA composite biomaterial exerted marked anti-infective effects and facilitated bone defect repair, while simultaneously controlling infection. Porous GS/DBM/PLA is therefore a promising composite biomaterial for use in bone tissue engineering. PMID:27284292

  7. Carbosilane polymers with hydrogen bond acidic functionalization for chemical preconcentrator applications

    NASA Astrophysics Data System (ADS)

    Simonson, Duane L.; McGill, R. Andrew; Higgins, Bernadette A.

    2008-04-01

    Vapor collection systems, including solid phase microextraction (SPME), require the ability to selectively collect and concentrate a sample from a large volume of air. In the case of SPME, polymers are needed to adhere to the fiber for greater reproducibility and longer lasting fibers. The polymerization of carbosilanes was investigated and produced polymers with molecular weights over 500,000. This polymer class was then functionalized with hexafluoro-2-propanol (HFIP) end groups that will selectively sorb hydrogen bond basic vapors. The results of vapor testing with these polymers utilizing a variety of platforms such as preconcentrators, Surface Acoustic Wave (SAW) sensors, and microcantilevers will be discussed.

  8. ALUMINUM-CONTAINING POLYMERS

    DTIC Science & Technology

    ALUMINUM COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, *POLYMERIZATION, *POLYMERS, ACRYLIC RESINS, ALKYL RADICALS, CARBOXYLIC ACIDS, COPOLYMERIZATION, LIGHT TRANSMISSION, STABILITY, STYRENES, TRANSPARENT PANELS.

  9. Physically Cross-linked Polymer Binder Induced by Reversible Acid-Base Interaction for High-Performance Silicon Composite Anodes.

    PubMed

    Lim, Sanghyun; Chu, Hodong; Lee, Kukjoo; Yim, Taeeun; Kim, Young-Jun; Mun, Junyoung; Kim, Tae-Hyun

    2015-10-28

    Silicon is greatly promising for high-capacity anode materials in lithium-ion batteries (LIBs) due to their exceptionally high theoretical capacity. However, it has a big challenge of severe volume changes during charge and discharge, resulting in substantial deterioration of the electrode and restricting its practical application. This conflict requires a novel binder system enabling reliable cyclability to hold silicon particles without severe disintegration of the electrode. Here, a physically cross-linked polymer binder induced by reversible acid-base interaction is reported for high performance silicon-anodes. Chemical cross-linking of polymer binders, mainly based on acidic polymers including poly(acrylic acid) (PAA), have been suggested as effective ways to accommodate the volume expansion of Si-based electrodes. Unlike the common chemical cross-linking, which causes a gradual and nonreversible fracturing of the cross-linked network, a physically cross-linked binder based on PAA-PBI (poly(benzimidazole)) efficiently holds the Si particles even after the large volume changes due to its ability to reversibly reconstruct ionic bonds. The PBI-containing binder, PAA-PBI-2, exhibited large capacity (1376.7 mAh g(-1)), high Coulombic efficiency (99.1%) and excellent cyclability (751.0 mAh g(-1) after 100 cycles). This simple yet efficient method is promising to solve the failures relating with pulverization and isolation from the severe volume changes of the Si electrode, and advance the realization of high-capacity LIBs.

  10. Effect of twist-orientation on mechanical properties of self-reinforced poly(lactic acid) screws in simulated body environment

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Masato; Kobayashi, Satoshi; composite engineering lab Team

    Poly(lactic acid) (PLA) attracts much attention as a typical biodegradable polymer, and has been applied as a bone fixation device. As one of the methods to improve mechanical properties of PLA bone fixation device, orientations of molecular chains have been investigated. However, conventional uniaxial drawing could not improve mechanical properties along the other loading direction than the drawing direction, such as torsion. In this study, screw is treated as a bone fixation device. In order to improve torsional strength of a bioabsorbable PLA screw, twist-orientation method has been developed. PLA screw is prepared through a series of routes including extrusion molding, extrusion drawing, twist-orientation and forging. This screw was immersed in the phosphate buffer solution for 0, 8, 16 and 24 weeks, then shear strength, orientation function, crystallinity and molecular weight were measured. As a result, twist-orientation improves the initial torsional strength of PLA screw without the decrease in initial shear strength. In addition, the shear strength on twist-oriented screw is equivalent that of non-twist oriented screw during immersion until 24 weeks. This result shown that the twist-orientation does not decrease shear strength after immersion.

  11. The synthesis, properties, and applications of hydrophilic polymers and copolymers of hydroxyalkyl esters of acrylic and methacrylic acids

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