Science.gov

Sample records for charged hydrogels prepared

  1. Dynamic loading stimulates chondrocyte biosynthesis when encapsulated in charged hydrogels prepared from poly(ethylene glycol) and chondroitin sulfate.

    PubMed

    Villanueva, Idalis; Gladem, Sara K; Kessler, Jeff; Bryant, Stephanie J

    2010-01-01

    This study aimed to elucidate the role of charge in mediating chondrocyte response to loading by employing synthetic 3D hydrogels. Specifically, neutral poly(ethylene glycol) (PEG) hydrogels were employed where negatively charged chondroitin sulfate (ChS), one of the main extracellular matrix components of cartilage, was systematically incorporated into the PEG network at 0%, 20% or 40% to control the fixed charge density. PEG hydrogels were employed as a control environment for extracellular events which occur as a result of loading, but which are not associated with a charged matrix (e.g., cell deformation and fluid flow). Freshly isolated bovine articular chondrocytes were embedded in the hydrogels and subject to dynamic mechanical stimulation (0.3Hz, 15% amplitude strains, 6h) and assayed for nitric oxide production, cell proliferation, proteoglycan synthesis, and collagen deposition. In the absence of loading, incorporation of charge inhibited cell proliferation by approximately 75%, proteoglycan synthesis by approximately 22-50% depending on ChS content, but had no affect on collagen deposition. Dynamic loading had no effect on cellular responses in PEG hydrogels. However, dynamically loading 20% ChS gels inhibited nitrite production by 50%, cell proliferation by 40%, but stimulated proteoglycan and collagen deposition by 162% and 565%, respectively. Dynamic loading of 40% ChS hydrogels stimulated nitrite production by 62% and proteoglycan synthesis by 123%, but inhibited cell proliferation by 54% and collagen deposition by 52%. Upon removing the load and culturing under free-swelling conditions for 36h, the enhanced matrix synthesis observed in the 20% ChS gels was not maintained suggesting that loading is necessary to stimulate matrix production. In conclusion, extracellular events associated with a charged matrix have a dramatic affect on how chondrocytes respond to mechanical stimulation within these artificial 3D matrices suggesting that streaming

  2. Controlled Delivery of Vancomycin via Charged Hydrogels

    PubMed Central

    Gustafson, Carl T.; Boakye-Agyeman, Felix; Brinkman, Cassandra L.; Reid, Joel M.; Patel, Robin; Bajzer, Zeljko; Dadsetan, Mahrokh; Yaszemski, Michael J.

    2016-01-01

    Surgical site infection (SSI) remains a significant risk for any clean orthopedic surgical procedure. Complications resulting from an SSI often require a second surgery and lengthen patient recovery time. The efficacy of antimicrobial agents delivered to combat SSI is diminished by systemic toxicity, bacterial resistance, and patient compliance to dosing schedules. We submit that development of localized, controlled release formulations for antimicrobial compounds would improve the effectiveness of prophylactic surgical wound antibiotic treatment while decreasing systemic side effects. Our research group developed and characterized oligo(poly(ethylene glycol)fumarate) / sodium methacrylate (OPF/SMA) charged copolymers as biocompatible hydrogel matrices. Here, we report the engineering of this copolymer for use as an antibiotic delivery vehicle in surgical applications. We demonstrate that these hydrogels can be efficiently loaded with vancomycin (over 500 μg drug per mg hydrogel) and this loading mechanism is both time- and charge-dependent. Vancomycin release kinetics are shown to be dependent on copolymer negative charge. In the first 6 hours, we achieved as low as 33.7% release. In the first 24 hours, under 80% of total loaded drug was released. Further, vancomycin release from this system can be extended past four days. Finally, we show that the antimicrobial activity of released vancomycin is equivalent to stock vancomycin in inhibiting the growth of colonies of a clinically derived strain of methicillin-resistant Staphylococcus aureus. In summary, our work demonstrates that OPF/SMA hydrogels are appropriate candidates to deliver local antibiotic therapy for prophylaxis of surgical site infection. PMID:26760034

  3. Controlled Delivery of Vancomycin via Charged Hydrogels.

    PubMed

    Gustafson, Carl T; Boakye-Agyeman, Felix; Brinkman, Cassandra L; Reid, Joel M; Patel, Robin; Bajzer, Zeljko; Dadsetan, Mahrokh; Yaszemski, Michael J

    2016-01-01

    Surgical site infection (SSI) remains a significant risk for any clean orthopedic surgical procedure. Complications resulting from an SSI often require a second surgery and lengthen patient recovery time. The efficacy of antimicrobial agents delivered to combat SSI is diminished by systemic toxicity, bacterial resistance, and patient compliance to dosing schedules. We submit that development of localized, controlled release formulations for antimicrobial compounds would improve the effectiveness of prophylactic surgical wound antibiotic treatment while decreasing systemic side effects. Our research group developed and characterized oligo(poly(ethylene glycol)fumarate)/sodium methacrylate (OPF/SMA) charged copolymers as biocompatible hydrogel matrices. Here, we report the engineering of this copolymer for use as an antibiotic delivery vehicle in surgical applications. We demonstrate that these hydrogels can be efficiently loaded with vancomycin (over 500 μg drug per mg hydrogel) and this loading mechanism is both time- and charge-dependent. Vancomycin release kinetics are shown to be dependent on copolymer negative charge. In the first 6 hours, we achieved as low as 33.7% release. In the first 24 hours, under 80% of total loaded drug was released. Further, vancomycin release from this system can be extended past four days. Finally, we show that the antimicrobial activity of released vancomycin is equivalent to stock vancomycin in inhibiting the growth of colonies of a clinically derived strain of methicillin-resistant Staphylococcus aureus. In summary, our work demonstrates that OPF/SMA hydrogels are appropriate candidates to deliver local antibiotic therapy for prophylaxis of surgical site infection. PMID:26760034

  4. Controlled Delivery of Vancomycin via Charged Hydrogels.

    PubMed

    Gustafson, Carl T; Boakye-Agyeman, Felix; Brinkman, Cassandra L; Reid, Joel M; Patel, Robin; Bajzer, Zeljko; Dadsetan, Mahrokh; Yaszemski, Michael J

    2016-01-01

    Surgical site infection (SSI) remains a significant risk for any clean orthopedic surgical procedure. Complications resulting from an SSI often require a second surgery and lengthen patient recovery time. The efficacy of antimicrobial agents delivered to combat SSI is diminished by systemic toxicity, bacterial resistance, and patient compliance to dosing schedules. We submit that development of localized, controlled release formulations for antimicrobial compounds would improve the effectiveness of prophylactic surgical wound antibiotic treatment while decreasing systemic side effects. Our research group developed and characterized oligo(poly(ethylene glycol)fumarate)/sodium methacrylate (OPF/SMA) charged copolymers as biocompatible hydrogel matrices. Here, we report the engineering of this copolymer for use as an antibiotic delivery vehicle in surgical applications. We demonstrate that these hydrogels can be efficiently loaded with vancomycin (over 500 μg drug per mg hydrogel) and this loading mechanism is both time- and charge-dependent. Vancomycin release kinetics are shown to be dependent on copolymer negative charge. In the first 6 hours, we achieved as low as 33.7% release. In the first 24 hours, under 80% of total loaded drug was released. Further, vancomycin release from this system can be extended past four days. Finally, we show that the antimicrobial activity of released vancomycin is equivalent to stock vancomycin in inhibiting the growth of colonies of a clinically derived strain of methicillin-resistant Staphylococcus aureus. In summary, our work demonstrates that OPF/SMA hydrogels are appropriate candidates to deliver local antibiotic therapy for prophylaxis of surgical site infection.

  5. Particle transport through hydrogels is charge asymmetric.

    PubMed

    Zhang, Xiaolu; Hansing, Johann; Netz, Roland R; DeRouchey, Jason E

    2015-02-01

    Transport processes within biological polymer networks, including mucus and the extracellular matrix, play an important role in the human body, where they serve as a filter for the exchange of molecules and nanoparticles. Such polymer networks are complex and heterogeneous hydrogel environments that regulate diffusive processes through finely tuned particle-network interactions. In this work, we present experimental and theoretical studies to examine the role of electrostatics on the basic mechanisms governing the diffusion of charged probe molecules inside model polymer networks. Translational diffusion coefficients are determined by fluorescence correlation spectroscopy measurements for probe molecules in uncharged as well as cationic and anionic polymer solutions. We show that particle transport in the charged hydrogels is highly asymmetric, with diffusion slowed down much more by electrostatic attraction than by repulsion, and that the filtering capability of the gel is sensitive to the solution ionic strength. Brownian dynamics simulations of a simple model are used to examine key parameters, including interaction strength and interaction range within the model networks. Simulations, which are in quantitative agreement with our experiments, reveal the charge asymmetry to be due to the sticking of particles at the vertices of the oppositely charged polymer networks.

  6. Particle Transport through Hydrogels Is Charge Asymmetric

    PubMed Central

    Zhang, Xiaolu; Hansing, Johann; Netz, Roland R.; DeRouchey, Jason E.

    2015-01-01

    Transport processes within biological polymer networks, including mucus and the extracellular matrix, play an important role in the human body, where they serve as a filter for the exchange of molecules and nanoparticles. Such polymer networks are complex and heterogeneous hydrogel environments that regulate diffusive processes through finely tuned particle-network interactions. In this work, we present experimental and theoretical studies to examine the role of electrostatics on the basic mechanisms governing the diffusion of charged probe molecules inside model polymer networks. Translational diffusion coefficients are determined by fluorescence correlation spectroscopy measurements for probe molecules in uncharged as well as cationic and anionic polymer solutions. We show that particle transport in the charged hydrogels is highly asymmetric, with diffusion slowed down much more by electrostatic attraction than by repulsion, and that the filtering capability of the gel is sensitive to the solution ionic strength. Brownian dynamics simulations of a simple model are used to examine key parameters, including interaction strength and interaction range within the model networks. Simulations, which are in quantitative agreement with our experiments, reveal the charge asymmetry to be due to the sticking of particles at the vertices of the oppositely charged polymer networks. PMID:25650921

  7. Facile preparation of photodegradable hydrogels by photopolymerization

    PubMed Central

    Ki, Chang Seok; Shih, Han; Lin, Chien-Chi

    2013-01-01

    Photodegradable hydrogels have emerged as a powerful material platform for studying and directing cell behaviors, as well as for delivering drugs. The premise of this technique is to use a cytocompatible light source to cleave linkers within a hydrogel, thus causing reduction of matrix stiffness or liberation of matrix-tethered biomolecules in a spatial-temporally controlled manner. The most commonly used photodegradable units are molecules containing nitrobenzyl moieties that absorb light in the ultraviolet (UV) to lower visible wavelengths (~280 to 450 nm). Because photodegradable linkers and hydrogels reported in the literature thus far are all sensitive to UV light, highly efficient UV-mediated photopolymerizations are less likely to be used as the method to prepare these hydrogels. As a result, currently available photodegradable hydrogels are formed by redox-mediated radical polymerizations, emulsion polymerizations, Michael-type addition reactions, or orthogonal click chemistries. Here, we report the first photodegradable poly(ethylene glycol)-based hydrogel system prepared by step-growth photopolymerization. The model photolabile peptide cross-linkers, synthesized by conventional solid phase peptide synthesis, contained terminal cysteines for step-growth thiol-ene photo-click reactions and a UV-sensitive 2-nitrophenylalanine residue in the peptide backbone for photo-cleavage. Photolysis of this peptide was achieved through adjusting UV light exposure time and intensity. Photopolymerization of photodegradable hydrogels containing photolabile peptide cross-linkers was made possible via a highly efficient visible light-mediated thiol-ene photo-click reaction using a non-cleavage type photoinitiator eosin-Y. Rapid gelation was confirmed by in situ photo-rheometry. Flood UV irradiation at controlled wavelength and intensity was used to demonstrate the photodegradability of these photopolymerized hydrogels. PMID:23894212

  8. Charge-discharge characteristics of nickel/zinc battery with polymer hydrogel electrolyte

    NASA Astrophysics Data System (ADS)

    Iwakura, Chiaki; Murakami, Hiroki; Nohara, Shinji; Furukawa, Naoji; Inoue, Hiroshi

    A new nickel/zinc (Ni/Zn) battery was assembled by using polymer hydrogel electrolyte prepared from cross-linked potassium poly(acrylate) and KOH aqueous solution, and its charge-discharge characteristics were investigated. The experimental Ni/Zn cell with the polymer hydrogel electrolyte exhibited well-defined charge-discharge curves and remarkably improved charge-discharge cycle performance, compared to that with a KOH aqueous solution. Moreover, it was found that dendritic growth hardly occurred on the zinc electrode surface during charge-discharge cycles in the polymer hydrogel electrolyte. These results indicate that the polymer hydrogel electrolyte can successfully be used in Ni/Zn batteries as an electrolyte with excellent performance.

  9. Hydrogel: Preparation, characterization, and applications: A review.

    PubMed

    Ahmed, Enas M

    2015-03-01

    Hydrogel products constitute a group of polymeric materials, the hydrophilic structure of which renders them capable of holding large amounts of water in their three-dimensional networks. Extensive employment of these products in a number of industrial and environmental areas of application is considered to be of prime importance. As expected, natural hydrogels were gradually replaced by synthetic types due to their higher water absorption capacity, long service life, and wide varieties of raw chemical resources. Literature on this subject was found to be expanding, especially in the scientific areas of research. However, a number of publications and technical reports dealing with hydrogel products from the engineering points of view were examined to overview technological aspects covering this growing multidisciplinary field of research. The primary objective of this article is to review the literature concerning classification of hydrogels on different bases, physical and chemical characteristics of these products, and technical feasibility of their utilization. It also involved technologies adopted for hydrogel production together with process design implications, block diagrams, and optimized conditions of the preparation process. An innovated category of recent generations of hydrogel materials was also presented in some details. PMID:25750745

  10. Hydrogel: Preparation, characterization, and applications: A review

    PubMed Central

    Ahmed, Enas M.

    2013-01-01

    Hydrogel products constitute a group of polymeric materials, the hydrophilic structure of which renders them capable of holding large amounts of water in their three-dimensional networks. Extensive employment of these products in a number of industrial and environmental areas of application is considered to be of prime importance. As expected, natural hydrogels were gradually replaced by synthetic types due to their higher water absorption capacity, long service life, and wide varieties of raw chemical resources. Literature on this subject was found to be expanding, especially in the scientific areas of research. However, a number of publications and technical reports dealing with hydrogel products from the engineering points of view were examined to overview technological aspects covering this growing multidisciplinary field of research. The primary objective of this article is to review the literature concerning classification of hydrogels on different bases, physical and chemical characteristics of these products, and technical feasibility of their utilization. It also involved technologies adopted for hydrogel production together with process design implications, block diagrams, and optimized conditions of the preparation process. An innovated category of recent generations of hydrogel materials was also presented in some details. PMID:25750745

  11. Magnetic hyaluronate hydrogels: preparation and characterization

    NASA Astrophysics Data System (ADS)

    Tóth, Ildikó Y.; Veress, Gábor; Szekeres, Márta; Illés, Erzsébet; Tombácz, Etelka

    2015-04-01

    A novel soft way of hyaluronate (HyA) based magnetic hydrogel preparation was revealed. Magnetite nanoparticles (MNPs) were prepared by co-precipitation. Since the naked MNPs cannot be dispersed homogenously in HyA-gel, their surface was modified with natural and biocompatible chondroitin-sulfate-A (CSA) to obtain CSA-coated MNPs (CSA@MNPs). The aggregation state of MNPs and that loaded with increasing amount of CSA up to 1 mmol/g was measured by dynamic light scattering at pH~6. Only CSA@MNP with ≥0.2 mmol/g CSA content was suitable for magnetic HyA-gel preparation. Rheological studies showed that the presence of CSA@MNP with up to 2 g/L did not affect the hydrogel's rheological behavior significantly. The results suggest that the HyA-based magnetic hydrogels may be promising formulations for future biomedical applications, e.g. as intra-articular injections in the treatment of osteoarthritis.

  12. Surface elasticity and charge concentration-dependent endothelial cell attachment to copolymer polyelectrolyte hydrogel.

    PubMed

    Kim, Seonghwan; English, Anthony E; Kihm, Kenneth D

    2009-01-01

    The surface micromechanical properties of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloxyethyl trimethyl ammonium chloride (MAETAC) copolymer hydrogels are probed using atomic force microscopy. HEMA-MAETAC polyelectrolyte hydrogels with increasing positive charge concentrations ranging from 0 to 400mM in increments of 40mM, are fabricated using different proportions of HEMA and MAETAC monomers. Increasing proportions of positively charged MAETAC monomers produce hydrogels with increasingly swollen states and correspondingly decreasing measures of stiffness, or Young's modulus. Increasing the relative proportion of charged monomers also increases the hysteresis in the approaching and retracting components of the force spectroscopy curves. When these hydrogels are equilibrated in cell-culture media without fetal bovine serum and a pH-controlled CO(2) environment, precipitation reactions increase the variability of the Young's modulus estimates. Adding a buffer, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, maintains physiological pH without the use of a CO(2) environment, and thus reduces salt precipitation reactions and the variability of the Young's modulus. The attachment of porcine pulmonary artery endothelial cells increases with increasing prepared hydrogel charge concentration and decreasing elasticity. PMID:18774763

  13. Rapid fabrication of reconstructible hydrogels by electrophoretic microbead adhesion.

    PubMed

    Asoh, Taka-Aki; Kikuchi, Akihiko

    2012-10-14

    Hydrogel constructs were rapidly fabricated via the electrophoretic adhesion of oppositely charged microbeads. The reversible preparation of hydrogel constructs was achieved by the reconstruction of microbead networks.

  14. Nanoparticle gel electrophoresis: bare charged spheres in polyelectrolyte hydrogels.

    PubMed

    Li, Fei; Hill, Reghan J

    2013-03-15

    Nanoparticle gel electrophoresis has recently emerged as an attractive means of separating and characterizing nanoparticles. Consequently, a theory that accounts for electroosmotic flow in the gel, and coupling of the nanoparticle and hydrogel electrostatics and hydrodynamics, is required, particularly for gels in which the mesh size is comparable to or smaller than the particle radii. Here, we present an electrokinetic model for charged, spherical colloidal particles undergoing electrophoresis in charged (polyelectrolyte) hydrogels: the gel-electrophoresis analogue of Henry's theory for electrophoresis in Newtonian electrolytes. We compare numerically exact solutions of the model with several independent asymptotic approximations, identifying regions in the parameter space where these approximations are accurate or break down. As previously assumed in the literature, Henry's formula, modified by the addition of a constant electroosmotic flow mobility, is accurate only for nanoparticles that are small compared to the hydrogel mesh size. We derived an exact analytical solution of the full model by judiciously modifying the theory of Allison et al. for uncharged gels, drawing on the superposition methodology of Doane et al. to account for hydrogel charge. This furnishes accurate and economical mobility predictions for the entire parameter space. The present model suggests that nanoparticle size separations (with diameters ≲40 nm) are optimal at low ionic strength, with a gel mesh size that is selected according to the particle charging mechanism. For weakly charged particles, optimal size separation is achieved when the Brinkman screening length is matched to the mean particle size. PMID:23153681

  15. Preparation of DNA-crosslinked polyacrylamide hydrogels.

    PubMed

    Previtera, Michelle L; Langrana, Noshir A

    2014-01-01

    Mechanobiology is an emerging scientific area that addresses the critical role of physical cues in directing cell morphology and function. For example, the effect of tissue elasticity on cell function is a major area of mechanobiology research because tissue stiffness modulates with disease, development, and injury. Static tissue-mimicking materials, or materials that cannot alter stiffness once cells are plated, are predominately used to investigate the effects of tissue stiffness on cell functions. While information gathered from static studies is valuable, these studies are not indicative of the dynamic nature of the cellular microenvironment in vivo. To better address the effects of dynamic stiffness on cell function, we developed a DNA-crosslinked polyacrylamide hydrogel system (DNA gels). Unlike other dynamic substrates, DNA gels have the ability to decrease or increase in stiffness after fabrication without stimuli. DNA gels consist of DNA crosslinks that are polymerized into a polyacrylamide backbone. Adding and removing crosslinks via delivery of single-stranded DNA allows temporal, spatial, and reversible control of gel elasticity. We have shown in previous reports that dynamic modulation of DNA gel elasticity influences fibroblast and neuron behavior. In this report and video, we provide a schematic that describes the DNA gel crosslinking mechanisms and step-by-step instructions on the preparation DNA gels. PMID:25226067

  16. Preparation of polyphosphazene hydrogels for enzyme immobilization.

    PubMed

    Qian, Yue-Cheng; Chen, Peng-Cheng; He, Gui-Jin; Huang, Xiao-Jun; Xu, Zhi-Kang

    2014-01-01

    We report on the synthesis and application of a new hydrogel based on a methacrylate substituted polyphosphazene. Through ring-opening polymerization and nucleophilic substitution, poly[bis(methacrylate)phosphazene] (PBMAP) was successfully synthesized from hexachlorocyclotriphosphazene. By adding PBMAP to methacrylic acid solution and then treating with UV light, we could obtain a cross-linked polyphosphazene network, which showed an ultra-high absorbency for distilled water. Lipase from Candida rugosa was used as the model lipase for entrapment immobilization in the hydrogel. The influence of methacrylic acid concentration on immobilization efficiency was studied. Results showed that enzyme loading reached a maximum of 24.02 mg/g with an activity retention of 67.25% when the methacrylic acid concentration was 20% (w/w). PMID:25006790

  17. Preparation and characterization of amidated pectin based hydrogels for drug delivery system.

    PubMed

    Mishra, R K; Datt, M; Pal, K; Banthia, A K

    2008-06-01

    In the current studies attempts were made to prepare hydrogels by chemical modification of pectin with ethanolamine (EA) in different proportions. Chemically modified pectin products were crosslinked with glutaraldehyde reagent for preparing hydrogels. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), organic elemental analysis, X-ray diffraction studies (XRD), swelling studies, biocompatibility and hemocompatibility studies. Mechanical properties of the prepared hydrogels were evaluated by tensile test. The hydrogels were loaded with salicylic acid (used as a model drug) and drug release studies were done in a modified Franz's diffusion cell. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. XRD studies indicated increase in crystallinity in the hydrogels as compared to unmodified pectin. The degree of amidation (DA) and molar and mass reaction yields (YM and YN) was calculated based on the results of organic elemental analysis. The hydrogels showed good water holding properties and were found to be compatible with B-16 melanoma cells & human blood.

  18. Nanostructurally Controlled Hydrogel Based on Small‐Diameter Native Chitin Nanofibers: Preparation, Structure, and Properties

    PubMed Central

    Kochumalayil, Joby; Cervin, Nicholas Tchang; Zhou, Qi

    2016-01-01

    Abstract Chitin nanofibers of unique structure and properties can be obtained from crustacean and fishery waste. These chitin nanofibers have roughly 4 nm diameters, aspect ratios between 25–250, a high degree of acetylation and preserved crystallinity, and can be potentially applied in hydrogels. Hydrogels with a chitin nanofiber content of 0.4, 0.6, 0.8, 1.0, 2.0, and 3.0 wt % were successfully prepared. The methodology for preparation is new, environmentally friendly, and simple as gelation is induced by neutralization of the charged colloidal mixture, inducing precipitation and secondary bond interaction between nanofibers. Pore structure and pore size distributions of corresponding aerogels are characterized using auto‐porosimetry, revealing a substantial fraction of nanoscale pores. To the best of our knowledge, the values for storage (13 kPa at 3 wt %) and compression modulus (309 kPa at 2 wt %) are the highest reported for chitin nanofibers hydrogels. PMID:27061912

  19. Preparation of supramolecular hydrogel-enzyme hybrids exhibiting biomolecule-responsive gel degradation.

    PubMed

    Shigemitsu, Hajime; Fujisaku, Takahiro; Onogi, Shoji; Yoshii, Tatsuyuki; Ikeda, Masato; Hamachi, Itaru

    2016-09-01

    Hydrogelators are small, self-assembling molecules that form supramolecular nanofiber networks that exhibit unique dynamic properties. Development of supramolecular hydrogels that degrade in response to various biomolecules could potentially be used for applications in areas such as drug delivery and diagnostics. Here we provide a synthetic procedure for preparing redox-responsive supramolecular hydrogelators that are used to create hydrogels that degrade in response to oxidizing or reducing conditions. The synthesis takes ∼2-4 d, and it can potentially be carried out in parallel to prepare multiple hydrogelator candidates. This described solid-phase peptide synthesis protocol can be used to produce previously described hydrogelators or to construct a focused molecular library to efficiently discover and optimize new hydrogelators. In addition, we describe the preparation of redox-responsive supramolecular hydrogel-enzyme hybrids that are created by mixing aqueous solutions of hydrogelators and enzymes, which requires 2 h for completion. The resultant supramolecular hydrogel-enzyme hybrids exhibit gel degradation in response to various biomolecules, and can be rationally designed by connecting the chemical reactions of the hydrogelators with enzymatic reactions. Gel degradation in response to biomolecules as triggers occurs within a few hours. We also describe the preparation of hydrogel-enzyme hybrids arrayed on flat glass slides, enabling high-throughput analysis of biomolecules such as glucose, uric acid, lactate and so on by gel degradation, which is detectable by the naked eye. The protocol requires ∼6 h to prepare the hydrogel-enzyme hybrid array and to complete the biomolecule assay. PMID:27560177

  20. Preparation of supramolecular hydrogel-enzyme hybrids exhibiting biomolecule-responsive gel degradation.

    PubMed

    Shigemitsu, Hajime; Fujisaku, Takahiro; Onogi, Shoji; Yoshii, Tatsuyuki; Ikeda, Masato; Hamachi, Itaru

    2016-09-01

    Hydrogelators are small, self-assembling molecules that form supramolecular nanofiber networks that exhibit unique dynamic properties. Development of supramolecular hydrogels that degrade in response to various biomolecules could potentially be used for applications in areas such as drug delivery and diagnostics. Here we provide a synthetic procedure for preparing redox-responsive supramolecular hydrogelators that are used to create hydrogels that degrade in response to oxidizing or reducing conditions. The synthesis takes ∼2-4 d, and it can potentially be carried out in parallel to prepare multiple hydrogelator candidates. This described solid-phase peptide synthesis protocol can be used to produce previously described hydrogelators or to construct a focused molecular library to efficiently discover and optimize new hydrogelators. In addition, we describe the preparation of redox-responsive supramolecular hydrogel-enzyme hybrids that are created by mixing aqueous solutions of hydrogelators and enzymes, which requires 2 h for completion. The resultant supramolecular hydrogel-enzyme hybrids exhibit gel degradation in response to various biomolecules, and can be rationally designed by connecting the chemical reactions of the hydrogelators with enzymatic reactions. Gel degradation in response to biomolecules as triggers occurs within a few hours. We also describe the preparation of hydrogel-enzyme hybrids arrayed on flat glass slides, enabling high-throughput analysis of biomolecules such as glucose, uric acid, lactate and so on by gel degradation, which is detectable by the naked eye. The protocol requires ∼6 h to prepare the hydrogel-enzyme hybrid array and to complete the biomolecule assay.

  1. Preparation of Graphene Oxide-Based Hydrogels as Efficient Dye Adsorbents for Wastewater Treatment

    NASA Astrophysics Data System (ADS)

    Guo, Haiying; Jiao, Tifeng; Zhang, Qingrui; Guo, Wenfeng; Peng, Qiuming; Yan, Xuehai

    2015-06-01

    Graphene oxide (GO) sheets exhibit superior adsorption capacity for removing organic dye pollutants from an aqueous environment. In this paper, the facile preparation of GO/polyethylenimine (PEI) hydrogels as efficient dye adsorbents has been reported. The GO/PEI hydrogels were achieved through both hydrogen bonding and electrostatic interactions between amine-rich PEI and GO sheets. For both methylene blue (MB) and rhodamine B (RhB), the as-prepared hydrogels exhibit removal rates within about 4 h in accordance with the pseudo-second-order model. The dye adsorption capacity of the hydrogel is mainly attributed to the GO sheets, whereas the PEI was incorporated to facilitate the gelation process of GO sheets. More importantly, the dye-adsorbed hydrogels can be conveniently separated from an aqueous environment, suggesting potential large-scale applications of the GO-based hydrogels for organic dye removal and wastewater treatment.

  2. Characterization and behavior of composite hydrogel prepared from bamboo shoot cellulose and β-cyclodextrin.

    PubMed

    Liu, Shumin; Luo, Wenchao; Huang, Huihua

    2016-08-01

    Carboxymethyl cellulose was derived from bamboo shoot cellulose via chemical modification and was prepared into composite hydrogels by cross-linkage with β-cyclodextrin using epichlorohydrin as crossing agent. The structure of the prepared hydrogel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The results showed that the prepared composite hydrogel was sensitive to surrounding changes in pH value, temperature and ionic strength. Under the surroundings of low temperatures and high pH values, the prepared hydrogel had significant high swelling ratios (23338±988% at 15°C and 6937±112% at pH 8.0, respectively). In the solution of 0.1mol/L NaCl, the hydrogel showed the maximum water retention rate (48.73%). Sodium salicylate was used as the model drug to study the behaviors of hydrogel adsorption and release in simulated intestinal (at pH 7.4) and gastric liquid (at pH 1.8) surroundings. The prepared composite hydrogel exhibited higher drug release ratio in simulated intestinal liquid (63.09% after 380min) than in gastric liquid (22.09% after 400min). These pH responses of the prepared composite hydrogel showed its potential applications, especially as the drug carrier to attain control release of drugs under different surrounding conditions or organs in human body. PMID:27174909

  3. Design, preparation and characterization of ulvan based thermosensitive hydrogels.

    PubMed

    Morelli, Andrea; Betti, Margherita; Puppi, Dario; Chiellini, Federica

    2016-01-20

    The present study is focused on the exploitation and conversion of sulphated polysaccharides obtained from waste algal biomass into high value added material for biomedical applications. ulvan, a sulphated polysaccharide extracted from green seaweeds belonging to Ulva sp. was selected as a suitable material due to its chemical versatility and widely ascertained bioactivity. To date the present work represents the first successful attempt of preparation of ulvan-based hydrogels displaying thermogelling behaviour. ulvan was provided with thermogelling properties by grafting poly(N-isopropylacrylamide) chains onto its backbone as thermosensitive component. To this aim ulvan was properly modified with acryloyl groups to act as macroinitiator in the radical polymerization of N-isopropylacrylamide, induced by UV irradiation through a "grafting from" method. The thermogelling properties of the copolymer were investigated by thermal and rheological analyses. Sol-gel transition of the copolymer was found to occur at 30-31 °C thus indicating the feasibility of ulvan for being used as in-situ hydrogel forming systems for biomedical applications. PMID:26572453

  4. Preparation and characterization of quaternary ammonium chitosan hydrogel with significant antibacterial activity.

    PubMed

    Fan, Lihong; Yang, Jing; Wu, Huan; Hu, Zhihai; Yi, Jiayan; Tong, Jun; Zhu, Xiaoming

    2015-08-01

    Quaternary ammonium chitosan (HACC)/polyvinyl alcohol (PVA)/polyethylene oxide (PEO) hydrogels were prepared using gamma radiation. The chemical structure of the hydrogels was characterized using FT-IR. The results revealed that HACC, PVA and PEO were perfectly compatible and interacted via the hydrogen bonds. As revealed by SEM, scaffolds with a homogeneous interconnected pore structure were obtained after lyophilizing the hydrogels. The influence of different radiation doses and weight ratios on properties including gel content, swelling ability, water evaporation rate and mechanical properties were investigated. It indicated that the hydrogels had the good swelling ability, water evaporation rate and mechanical properties. In vitro antibacterial activity assessment, the hydrogels exhibited a pronounced inhibitory effect against two bacteria (Staphylococcus aureus and Escherichia coli). Therefore, the hydrogels showed a promising potential to be applied as wound dressing. PMID:25895959

  5. Hyaluronic acid/chondroitin sulfate-based hydrogel prepared by gamma irradiation technique.

    PubMed

    Zhao, Linlin; Gwon, Hui-Jeong; Lim, Youn-Mook; Nho, Young-Chang; Kim, So Yeon

    2014-02-15

    Gamma-ray irradiation of novel hydrogels was used to develop a biocompatible hydrogel system for skin tissue engineering. These novel hydrogels are composed of natural polymers including hyaluronic acid (HA) and chondroitin sulfate (CS), and the synthetic polymer, poly(vinyl alcohol) (PVA). The γ-ray irradiation method has advantages, such as relatively simple manipulation without need of any extra reagents for polymerization and cross-linking. We synthesized HA and CS derivatives with polymerizable residues. The HA/CS/PVA hydrogels with various compositions were prepared by using γ-ray irradiation technique and their physicochemical properties were investigated to evaluate the feasibility of their use as artificial skin substitutes. HA/CS/PVA hydrogels showed an 85-88% degree of gelation under 15 kGy radiation. All HA/CS/PVA hydrogels exhibited more than 90% water content and reached an equilibrium swelling state within 24h. Hydrogels with higher concentrations of hyaluronidase solution and HA/CS content had proportionally higher enzymatic degradation rates. The drug release behaviors from HA/CS/PVA hydrogels were influenced by the composition of the hydrogel and drug properties. Exposure of human keratinocyte (HaCaT) culture to the extracts of HA/CS/PVA hydrogels did not significantly affect the cell viability. All HaCaT cell cultures exposed to the extracts of HA/CS/PVA hydrogels exhibited greater than 92% cell viability. The HaCaT growth in HA/CS/PVA hydrogels gradually increased as a function of culture time. After 7 days, the HaCaT cells in all HA/CA/PVA hydrogels exhibited more than 80% viability compared to the control group HaCaT culture on a culture plate. PMID:24507324

  6. Biodegradable DNA-enabled poly(ethylene glycol) hydrogels prepared by copper-free click chemistry.

    PubMed

    Barker, Karolyn; Rastogi, Shiva K; Dominguez, Jose; Cantu, Travis; Brittain, William; Irvin, Jennifer; Betancourt, Tania

    2016-01-01

    Significant research has focused on investigating the potential of hydrogels in various applications and, in particular, in medicine. Specifically, hydrogels that are biodegradable lend promise to many therapeutic and biosensing applications. Endonucleases are critical for mechanisms of DNA repair. However, they are also known to be overexpressed in cancer and to be present in wounds with bacterial contamination. In this work, we set out to demonstrate the preparation of DNA-enabled hydrogels that could be degraded by nucleases. Specifically, hydrogels were prepared through the reaction of dibenzocyclooctyne-functionalized multi-arm poly(ethylene glycol) with azide-functionalized single-stranded DNA in aqueous solutions via copper-free click chemistry. Through the use of this method, biodegradable hydrogels were formed at room temperature in buffered saline solutions that mimic physiological conditions, avoiding possible harmful effects associated with other polymerization techniques that can be detrimental to cells or other bioactive molecules. The degradation of these DNA-cross-linked hydrogels upon exposure to the model endonucleases Benzonase(®) and DNase I was studied. In addition, the ability of the hydrogels to act as depots for encapsulation and nuclease-controlled release of a model protein was demonstrated. This model has the potential to be tailored and expanded upon for use in a variety of applications where mild hydrogel preparation techniques and controlled material degradation are necessary including in drug delivery and wound healing systems. PMID:26541212

  7. Biodegradable DNA-enabled poly(ethylene glycol) hydrogels prepared by copper-free click chemistry.

    PubMed

    Barker, Karolyn; Rastogi, Shiva K; Dominguez, Jose; Cantu, Travis; Brittain, William; Irvin, Jennifer; Betancourt, Tania

    2016-01-01

    Significant research has focused on investigating the potential of hydrogels in various applications and, in particular, in medicine. Specifically, hydrogels that are biodegradable lend promise to many therapeutic and biosensing applications. Endonucleases are critical for mechanisms of DNA repair. However, they are also known to be overexpressed in cancer and to be present in wounds with bacterial contamination. In this work, we set out to demonstrate the preparation of DNA-enabled hydrogels that could be degraded by nucleases. Specifically, hydrogels were prepared through the reaction of dibenzocyclooctyne-functionalized multi-arm poly(ethylene glycol) with azide-functionalized single-stranded DNA in aqueous solutions via copper-free click chemistry. Through the use of this method, biodegradable hydrogels were formed at room temperature in buffered saline solutions that mimic physiological conditions, avoiding possible harmful effects associated with other polymerization techniques that can be detrimental to cells or other bioactive molecules. The degradation of these DNA-cross-linked hydrogels upon exposure to the model endonucleases Benzonase(®) and DNase I was studied. In addition, the ability of the hydrogels to act as depots for encapsulation and nuclease-controlled release of a model protein was demonstrated. This model has the potential to be tailored and expanded upon for use in a variety of applications where mild hydrogel preparation techniques and controlled material degradation are necessary including in drug delivery and wound healing systems.

  8. Characterization of Network Structure of Polyacrylamide Based Hydrogels Prepared By Radiation Induced Polymerization

    SciTech Connect

    Mahmudi, Naim; Sen, Murat; Gueven, Olgun; Rendevski, Stojan

    2007-04-23

    In this study network structure of polyacrylamide based hydrogels prepared by radiation induced polymerization has been investigated. Polyacrylamide based hydrogels in the rod form were prepared by copolymerization of acrylamide(AAm) with hydroxyl ethyl methacrylate(HEMA) and methyl acrylamide(MAAm) in the presence of cross-linking agent and water by gamma rays at ambient temperature. Molecular weight between cross-links and effective cross-link density of hydrogels were calculated from swelling as well as shear modulus data obtained from compression tests. The results have shown that simple compression analyses can be used for the determination of effective cross-link density of hydrogels without any need to some polymer-solvent based parameters as in the case of swelling based determinations. Diffusion of water into hydrogels was examined by analyzing water absorption kinetics and the effect of network, structure on the diffusion type and coefficient was discussed.

  9. Nonlinear effects on electrophoresis of a charged dielectric nanoparticle in a charged hydrogel medium

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; De, Simanta

    2016-09-01

    The impact of the solid polarization of a charged dielectric particle in gel electrophoresis is studied without imposing a weak-field or a thin Debye length assumption. The electric polarization of a dielectric particle due to an external electric field creates a non-uniform surface charge density, which in turn creates a non-uniform Debye layer at the solid-gel interface. The solid polarization of the particle, the polarization of the double layer, and the electro-osmosis of mobile ions within the hydrogel medium create a nonlinear effect on the electrophoresis. We have incorporated those nonlinear effects by considering the electrokinetics governed by the Stokes-Brinkman-Nernst-Planck-Poisson equations. We have computed the governing nonlinear coupled set of equations numerically by adopting a finite volume based iterative algorithm. Our numerical method is tested for accuracy by comparing with several existing results on free-solution electrophoresis as well as results based on the Debye-Hückel approximation. Our computed result shows that the electrophoretic velocity decreases with the rise of the particle dielectric permittivity constant and attains a saturation limit at large values of permittivity. A significant impact of the solid polarization is found in gel electrophoresis compared to the free-solution electrophoresis.

  10. Preparation and characterization of chitosan/gelatin/PVA hydrogel for wound dressings.

    PubMed

    Fan, Lihong; Yang, Huan; Yang, Jing; Peng, Min; Hu, Jin

    2016-08-01

    Chitosan (CS)/gelatin (Gel)/polyvinyl alcohol (PVA) hydrogels were prepared by the gamma irradiation method for usage in wound dressing applications. Chitosan and gelatin solution was mixed with poly(vinyl alcohol) (PVA) solution at different weight ratios of CS/Gel of 1:3, 1:2, 1:1, 2:1 and 3:1. The hydrogels irradiated at 40kGy. The structure of the hydrogels was characterized by using FT-IR and SEM. The CS/Gel/PVA hydrogels were characterized for physical properties and blood clotting activity. The tensile strength of CS/Gel/PVA hydrogel enhanced than on the basis of the Gel/PVA hydrogel. The highest tensile strength reached the 2.2Mpa. All hydrogels have shown a good coagulation effect. It takes only 5min for the BCI index to reached 0.032 only 5min when the weight ratio of CS/Gel was 1:1. It means that the hemostatic effect of hydrogels were optimal. And the hydrogrls also showed good pH-sensitivity, swelling ability and water evaporation rate. Therefore, this hydrogel showed a promising potential to be applied as wound dressing. PMID:27112893

  11. Nitrile Oxide-Norbornene Cycloaddition as a Bioorthogonal Crosslinking Reaction for the Preparation of Hydrogels.

    PubMed

    Truong, Vinh X; Zhou, Kun; Simon, George P; Forsythe, John S

    2015-10-01

    This communication describes the first application of cycloaddition between an in situ generated nitrile oxide with norbornene leading to a polymer crosslinking reaction for the preparation of poly(ethylene glycol) hydrogels under physiological conditions. Hydrogels with high water content and robust physical strength are readily formed within 2-5 min by a simple two-solution mixing method which allows 3D encapsulation of neuronal cells. This bioorthogonal crosslinking reaction provides a simple yet highly effective method for preparation of hydrogels to be used in bioengineering.

  12. Preparation and in vitro cytocompatibility of chitosan-siloxane hybrid hydrogels.

    PubMed

    Shirosaki, Yuki; Hirai, Masashi; Hayakawa, Satoshi; Fujii, Eiji; Lopes, Maria A; Santos, José D; Osaka, Akiyoshi

    2015-01-01

    Injectable systems can be used in minimally invasive surgical applications. Although chitosan-glycerophosphate hydrogel systems are biodegradable and biocompatible, the long periods of time required for their effective gelation have severely limited their clinical application. The challenges currently facing researchers in this field are therefore focused on shortening the gelation time and biocompatibility of these materials to develop hydrogels suitable for clinical application. Chitosan and γ-glycidoxypropyltrimethoxysilane (GPTMS) hybrids have recently demonstrated good cytocompatibility with respect to human osteoblastic cells (MG63) and human bone marrow cells. Although these precursor sols could form gels under physiological conditions, they required neutralization with a sodium hydroxide solution. In this study, the chitosan-GPTMS hybrid systems were neutralized with glycerophosphate to prepare injectable hydrogels. The results revealed that the gelation time of the hydrogels could be controlled by the amount of GPTMS in the precursor sols. The in vitro cytocompatibility of the hydrogels were evaluated in terms of the proliferation of MG63 cells cultured either directly onto the hydrogels or indirectly onto the cell culture plate under a hydrogel insert. In the former case, the cells showed good attachment and proliferated for up to 7 days. Similar results were observed in the in direct culture. These results suggest that this new chitosan-GPTMS hydrogel could potentially be used as an injectable biomaterial in clinical applications.

  13. Preparation and properties of novel hydrogel based on chitosan modified by poly(amidoamine) dendrimer.

    PubMed

    He, Guanghua; Zhu, Chao; Ye, Shengyang; Cai, Weiquan; Yin, Yihua; Zheng, Hua; Yi, Ying

    2016-10-01

    Currently, chitosan (CTS) or chitosan derivatives hydrogels are applied in different fields, such as biological materials, medical materials and hygiene materials. In this study, novel chitosan hydrogels were successfully prepared by chitosan and poly(amidoamine) (PAMAM) dendrimer with glutaraldehyde serving as a cross-linking agent. Fourier transform infrared spectroscopy (FTIR), (1)H nuclear magnetic resonance ((1)H NMR) and gel permeation chromatography (GPC) were performed to characterize PAMAM. The structure and morphology of hydrogels were characterized by FTIR, thermo gravimetry analysis (TGA), and scanning electron microscopy (SEM). The swelling properties of the hydrogels were investigated in solutions of pH 1.0 and 7.4. The hydrogels showed good swelling capacities and pH-sensitive swelling properties. Besides, the antibacterial activities of the hydrogels against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were tested by optical density. Compared with the pure chitosan hydrogel, their antibacterial activities were significantly improved with the increase in the blending ratio of PAMAM. And with the increase in cross-linking agent and concentration of CTS, the antibacterial activities increased firstly and then slightly decreased. The hydrogel was expected to be a novel antibacterial material.

  14. Preparation and properties of novel hydrogel based on chitosan modified by poly(amidoamine) dendrimer.

    PubMed

    He, Guanghua; Zhu, Chao; Ye, Shengyang; Cai, Weiquan; Yin, Yihua; Zheng, Hua; Yi, Ying

    2016-10-01

    Currently, chitosan (CTS) or chitosan derivatives hydrogels are applied in different fields, such as biological materials, medical materials and hygiene materials. In this study, novel chitosan hydrogels were successfully prepared by chitosan and poly(amidoamine) (PAMAM) dendrimer with glutaraldehyde serving as a cross-linking agent. Fourier transform infrared spectroscopy (FTIR), (1)H nuclear magnetic resonance ((1)H NMR) and gel permeation chromatography (GPC) were performed to characterize PAMAM. The structure and morphology of hydrogels were characterized by FTIR, thermo gravimetry analysis (TGA), and scanning electron microscopy (SEM). The swelling properties of the hydrogels were investigated in solutions of pH 1.0 and 7.4. The hydrogels showed good swelling capacities and pH-sensitive swelling properties. Besides, the antibacterial activities of the hydrogels against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were tested by optical density. Compared with the pure chitosan hydrogel, their antibacterial activities were significantly improved with the increase in the blending ratio of PAMAM. And with the increase in cross-linking agent and concentration of CTS, the antibacterial activities increased firstly and then slightly decreased. The hydrogel was expected to be a novel antibacterial material. PMID:27238583

  15. Evaluation of different methods to prepare superabsorbent hydrogels based on deacetylated gellan.

    PubMed

    de Souza, Flavio Silva; de Mello Ferreira, Ivana Lourenço; da Silva Costa, Marcos Antonio; de Lima, Ana Luiza Ferreira; da Costa, Marcia Parente Melo; da Silva, Gustavo Monteiro

    2016-09-01

    This study stands out for analyzing distinct ways of preparing hydrogels from deacetylated gellan gum that have high swelling capacity and good thermal resistance. We carried out a thorough investigation, applying various combinations of different experimental parameters. Two preparation methods were evaluated, in which the pH was adjusted before or after thermal treatment of the gellan solution, with subsequent addition of the crosslinking agent, to assess the influence of preparation method on the conformation of the gellan chains regarding formation of double helices. The pH range tested varied from acid (2, 3 or 4) to basic (8, 9 or 10). Gellan solution was prepared in different concentrations. Both pure gellan and hydrogel samples were characterized by Fourier-transform infrared spectroscopy and thermogravimetry. Pure gellan was also characterized by atomic absorption spectroscopy. The swelling degree of the hydrogels was analyzed. The results showed that all the hydrogels had high swelling capacity (>400%), so they can be considered superabsorbent materials. Hydrogels prepared with acid pH in general had lower thermal resistance than samples prepared in alkaline pH, regardless of the preparation method. Samples prepared with alkaline pH tended to have initial decomposition temperature similar to that of pure gellan. PMID:27185144

  16. Preparation and characterization of keratin-based biocomposite hydrogels prepared by electron beam irradiation.

    PubMed

    Park, Mira; Kim, Byoung-Suhk; Shin, Hye Kyoung; Park, Soo-Jin; Kim, Hak-Yong

    2013-12-01

    The biocompatible and highly porous keratin-based hydrogels were prepared using electron beam irradiation (EBI). The conditions for keratin-based hydrogel formation were investigated depending on several conditions, including the presence of poly(vinyl alcohol) (PVA), concentration of keratin solution, EBI dose, and poly(ethylene imine) (PEI) additives. The pure keratin (human hair and wool) aqueous solution was not gelled by EBI, while the aqueous keratin solutions blended with PVA were gelled at an EBI dose of more than 90 kGy. Furthermore, in the presence of PEI, the aqueous keratin solution blended with PVA could be gelled at a considerably lower EBI dose, even at 10 kGy. This finding suggests that the PEI additives significantly influence the rate of gelation and that PEIs function as an accelerator during gelation. The resulting keratin-based hydrogels were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), gel fraction, degree of swelling, gel strength, and kinetics of swelling analyses.

  17. Pectin and charge modified pectin hydrogel beads as a colon-targeted drug delivery carrier.

    PubMed

    Jung, Jiyoung; Arnold, Robert D; Wicker, Louise

    2013-04-01

    The physical and chemical properties of commercial low methoxyl citrus pectins, CP 28 and CP 55, and a pectinmethylesterase (PME) charge modified citrus pectin (MP 38) were compared, and the differences in ability to encapsulate indomethacin in hydrogel beads was determined at 0.5 or 1.0% (w/v) indomethacin ratio, and 100, 200 or 300 mM CaCl(2) solution. In order to investigate the drug release characteristics, indomethacin loaded dried hydrogel beads were immersed in simulated gastric fluids (pH 1.2) for 2h, followed by immersing in simulated intestinal fluids (pH 7.4) for 3h. Pectin type was highly significant (p<0.0001) for encapsulation efficiency and in vitro release assay. Encapsulation efficiency was also highly affected (p<0.0001) by indomethacin ratio and CaCl(2) concentration. The accumulative release rate of indomethacin from pectin hydrogel bead was less than 15% in simulated gastro-intestinal fluids. MP 38 beads showed significantly higher entrapment efficiency and lower release rate than beads formed from CP 28 or CP 55. MP 38 hydrogel formulated with 300 mM CaCl(2) and 0.5% indomethacin ratio showed the highest entrapment efficiency. These studies suggest that charge modification of pectin improves encapsulation efficiency of drugs for colon targeted drug delivery system through oral administration.

  18. High resolution interferometry as a tool for characterization of swelling of weakly charged hydrogels subjected to amphiphile and cyclodextrin exposure.

    PubMed

    Gao, Ming; Gawel, Kamila; Stokke, Bjørn Torger

    2013-01-15

    A high resolution interferometric technique was used to determine swelling behavior of weakly charged polyacrylamide hydrogels in the presence of oppositely charged surfactants and subsequent exposure to cyclodextrins. Hydrogels of copolymerized acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid (0.22, 0.44, 0.88 mol%) crosslinked with bisacrylamide (3, 6, 12 mol%) were employed. The equilibrium swelling and swelling kinetics of the hydrogels were determined with 2nm resolution of the optical length and sampled at approximately 1 Hz. These properties were determined for the hydrogels exposed to cationic surfactants dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB) at concentrations from 10(-7) up to 2×10(-3)M. The distribution of surfactant within one AAM-co-AMPSA hydrogel equilibrated in CTAB/perylene solution was investigated by confocal laser scanning microscopy. Hydrogels equilibrated at selected surfactant concentrations were subsequently exposed to cyclodextrins (α-CD, β-CD, methyl-β-CD and γ-CD) forming inclusion complexes with the surfactants. The results show different types of behavior for the two surfactants used, arising from the difference in the length of surfactant hydrophobic tail. The changes in the surfactant induced swelling of the hydrogels are suggested to arise from the net effect of electrostatic screening of sulfonic acid-amide group interactions and surfactant micellization. Hydrogels with the largest charge density and the lowest crosslink density yielded the most pronounced changes in swelling properties on exposure to DTAB or CTAB. The hydrogels displayed swelling kinetics on stepwise changes in surfactant concentrations that depended on the surfactant concentration range. The high resolution monitoring of hydrogel swelling associated with supramolecular complex formation in three-component systems hydrogel-amphiphilic molecule-cyclodextrin provides more details on the swelling behavior than

  19. Preparation of biointeractive glycoprotein-conjugated hydrogels through metabolic oligosacchalide engineering.

    PubMed

    Iwasaki, Yasuhiko; Matsunaga, Aki; Fujii, Shuetsu

    2014-09-17

    In the current study, synthetic hydrogels containing metabolically engineered glycoproteins of mammalian cells were prepared for the first time and selectin-mediated cell adhesion on the hydrogel was demonstrated. A culture of HL-60 cells was supplemented with an appropriate volume of aqueous solution of N-methacryloyl mannosamine (ManMA) to give a final concentration of 5 mM. The cells were then incubated for 3 days to deliver methacryloyl groups to the glycoproteins of the cells. A transparent hydrogel was formed via redox radical polymerization of methacryloyl functionalized glycoproteins with 2-methacryloyloxyethyl phosphorylcholine and a cross-linker. Conjugation of the glycoproteins into the hydrogel was determined using Coomassie brilliant blue (CBB) and periodic acid-Schiff (PAS) staining. The surface density of P-selectin glycoprotein ligand-1 (PSGL-1) on the hydrogels was also detected using gold-colloid-labeled immunoassay. Finally, selectin-mediated cell adhesion on hydrogels containing glycoproteins was demonstrated. Selectin-mediated cell adhesion is considered an essential step in the progression of various diseases; therefore, hydrogels having glycoproteins could be useful in therapeutic and diagnostic applications.

  20. Preparation and antibacterial properties of O-carboxymethyl chitosan/lincomycin hydrogels.

    PubMed

    He, Guanghua; Chen, Xiang; Yin, Yihua; Cai, Weiquan; Ke, Wanwan; Kong, Yahui; Zheng, Hua

    2016-01-01

    In this study, O-carboxymethyl chitosan (O-CMCS) was synthesized from chitosan and monochloroacetic acid. Then O-CMCS hydrogel was prepared by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) in which the lincomycin was packaged. The Fourier transform infrared spectrum and scanning electron microscopy were adopted to characterize the structure and morphology of the product. The influences of dosage of EDC/NHS and concentration of O-CMCS on the swelling properties of the hydrogels were investigated. The hydrogels performed good swelling capacities and obvious pH-sensitive properties. The antibacterial activities of the hydrogels were tested against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Compared with pure O-CMCS hydrogels, the antibacterial activities of O-CMCS/lincomycin hydrogels were significantly improved with the increase in the concentration of lincomycin against E. coli and S. aureus. With the increase in dosage of crosslinking agent or concentration of O-CMCS, the antibacterial activities both decreased gradually against the two bacteria. O-CMCS/lincomycin hydrogel was expected to be used for antibacterial material in view of its significant antibacterial activities.

  1. Preparation and physico-chemical properties of hydrogels from carboxymethyl cassava starch crosslinked with citric acid

    NASA Astrophysics Data System (ADS)

    Boonkham, Sasikan; Sangseethong, Kunruedee; Chatakanon, Pathama; Niamnuy, Chalida; Nakasaki, Kiyohiko; Sriroth, Klanarong

    2014-06-01

    Recently, environmentally friendly hydrogels prepared from renewable bio-based resources have drawn significant attention from both industrial and academic sectors. In this study, chemically crosslinked hydrogels have been developed from cassava starch which is a bio-based polymer using a non-toxic citric acid as a crosslinking agent. Cassava starch was first modified by carboxymethylation to improve its water absorbency property. The carboxymethyl cassava starch (CMCS) obtained was then crosslinked with citric acid at different concentrations and reaction times. The gel fraction of hydrogels increased progressively with increasing citric acid concentration. Free swelling capacity of hydrogels in de-ionized water, saline solution and buffers at various pHs as well as absorption under load were investigated. The results revealed that swelling behavior and mechanical characteristic of hydrogels depended on the citric acid concentration used in reaction. Increasing citric acid concentration resulted in hydrogels with stronger network but lower swelling and absorption capacity. The cassava starch hydrogels developed were sensitive to ionic strength and pH of surrounding medium, showing much reduced swelling capacity in saline salt solution and acidic buffers.

  2. Polyelectrolyte Complex Hydrogels: Self-assembly and the Influence of Charged and Neutral Blocks

    NASA Astrophysics Data System (ADS)

    Srivastava, Samanvaya; Goldfeld, David; Levi, Adam; Mao, Jun; Chen, Wei; Tirrell, Matthew

    Polyelectrolyte complexes (PEC) form when oppositely charged polyelectrolyte chains spontaneously associate and phase separate in aqueous mediums. Bulk phase separation of the PECs can be evaded by combining one or both of the polyelectrolytes with a neutral polymer, thus engineering pathways for self-assembled PEC micelles and hydrogels. The PEC domains in these assemblies can encapsulate therapeutics as well as genetic materials and thus have tremendous potential in drug delivery and tissue engineering applications. We will present insights on the equilibrium structure and self-assembly kinetics of PEC hydrogels with large-scale ordering of the nanoscale PEC domains through detailed structure characterization and rheology studies of self-assembled materials comprising of functionalized polyallyl glycidyl ethers (PAGE) connected to either single poly(ethylene glycol) (PEG) chain to form diblock copolymers or as functionalized end-groups on a triblock copolymer with a PEG midblock. The effect of key parameters such as polymer concentration, polymer block lengths, salt, ionic strength, and degree of charge mismatch on the equilibrium materials properties will be discussed, with a special emphasis on the structure-defining role of the charged blocks and the structure-directing role of neutral blocks. Additionally, interesting similarities, and differences between structures and dynamics of hydrogels comprising diblock and corresponding triblock polyelectrolytes, respectively, will be discussed.

  3. Electrochemical biosensing platform using hydrogel prepared from ferrocene modified amino acid as highly efficient immobilization matrix.

    PubMed

    Qu, Fengli; Zhang, Yi; Rasooly, Avraham; Yang, Minghui

    2014-01-21

    To increase the loading of glucose oxidase (GOx) and simplify glucose biosensor fabrication, hydrogel prepared from ferrocene (Fc) modified amino acid phenylalanine (Phe, F) was utilized for the incorporation of GOx. The synthesized hydrogel displays good biocompatibility and contains a significant number of Fc moieties, which can be considered as an ideal matrix to immobilize enzymes for the preparation of mediator-based biosensors. The hydrogel was studied by scanning electron microscopy, which indicated that it was composed of nanofibers with a diameter of around 50-100 nm and length extended to 1 mm. With the addition of GOx into the hydrogel and by directly dropping the resulting biocomposite onto the electrode surface, a glucose biosensor, that displays good performance due to improved enzyme loading and efficient electron transfer, can be simply constructed. The favorable network structure and good biocompatibility of the hydrogel could effectively avoid enzyme leakage and maintain the bioactivity of the enzymes, which resulted in good stability of the biosensor. The biosensor was utilized for the detection of glucose in blood samples with results comparable to those obtained from the hospital. The hydrogel as a functional component of an amperometric biosensor has implications for future development of biosensors and for clinical applications. PMID:24383679

  4. Preparation and pharmaceutical/pharmacodynamic evaluation of topical brucine-loaded liposomal hydrogel.

    PubMed

    Wang, Junling; Yuan, Yuan; Liu, Changsheng; Zhu, Di; Shen, Xi; Yang, Baican

    2009-10-01

    To reduce the toxicity and enhance the therapeutic efficacy of brucine, a traditional Chinese medicine for relieving arthritic and traumatic pain, in this study, a novel brucine-loaded liposomal hydrogel (BLH) formulation, suitable for topical application, was developed. Spherical liposomes composed of lecithin and cholesterol, with brucine, was prepared by a modified ethanol-dripping method. High percentage (over 80%) of encapsulated brucine in liposomes was obtained. Topical liposomal hydrogel formulations were prepared by further incorporation of the prepared liposomes into structured carbopol 940 hydrogels with the concentration of carbopol 1.0%, the ratio of glycerol to carbopol 8:1 and the brucine content 0.1%. The liposomal hydrogel formulations provided an obvious promotion for skin permeation of bruicne while for the free brucine in hydrogels (BH), there was no detectable drug permeation through the skin. The safety evaluation showed that the prepared BLH were no irritation to both the broken and integrity skin. Pharmacodynamic evaluation revealed that the BLH showed a better therapeutic efficacy than that of the BH. So, it can be concluded that the BLH developed here could represent a safe, effective and promising transdermal formulation for local treatment of analgesic and anti-inflammatory disease.

  5. Bioactive electroconductive hydrogels: the effects of electropolymerization charge density on the storage stability of an enzyme-based biosensor.

    PubMed

    Kotanen, Christian N; Tlili, Chaker; Guiseppi-Elie, Anthony

    2012-02-01

    Electrode-supported hydrogels were conferred with the biospecificity of enzymes during the process of electropolymerization to give rise to a class of bioactive, stimuli-responsive co-joined interpenetrating networks of inherently conductive polymers and highly hydrated hydrogels. Glucose responsive biotransducers were prepared by potentiostatic electropolymerization [750 mV vs. Ag/AgCl (3 M KCl)] of pyrrole at Poly(hydoxyethyl methacrylate)-based hydrogel-coated Pt micro-electrodes (Φ = 100 μm) from aqueous solutions of pyrrole and glucose oxidase (GOx; 0.4 M pyrrole, 1.0 mg/ml GOx) to 1.0 and 10.0 mC/cm². Polypyrrole was them over-oxidized by cyclic voltammetry (0-1.2 V vs. Ag/AgCl, 40 cycles in PBKCl, pH = 7.0). Biotransducers were stored at 4 °C in PBKCl for up to 18 days. Amperometric dose-response at 0.4 V vs. Ag/AgCl followed by Lineweaver-Burk analysis produced enzyme kinetic parameters as a function of electropolymerization charge density and storage time. Apparent Michaelis constant (K (Mapp)) increased from 18.6-152.0 mM (1.0 mC/cm²) and from 2.7-6.1 mM (10.0 mC/cm²). Biotransducer sensitivity increased to 21.2 nA/mM after 18 days and to 12.8 pA/mM after 10 days for the 1.0 and 10.0 mC/cm² membranes, respectively. Maximum current, I (max), also increased over time to 2.7 nA (1.0 mC/cm²) and to 170 pA (10.0 mC/cm²). Electropolymerization of polypyrrole is shown to be an effective means for imparting bioactivity to a hydrogel-coated microelectrode. GOx was shown to be stabilized and to increase activity over time within the electroconductive hydrogel.

  6. First report of charge-transfer induced heat-set hydrogel. Structural insights and remarkable properties

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Subham; Maiti, Bappa; Bhattacharya, Santanu

    2016-05-01

    The remarkable ability of a charge-transfer (CT) complex prepared from a pyrene-based donor (Py-D) and a naphthalenediimide-based acceptor (NDI-A) led to the formation of a deep-violet in color, transparent hydrogel at room temperature (RT-gel). Simultaneously, the RT-gel was diluted beyond its critical gelator concentration (CGC) to obtain a transparent sol. Very interestingly, the resultant sol, on heating above 70 °C, transformed into a heat-set gel instantaneously with a hitherto unknown CGC value. Detailed studies revealed the smaller globular aggregates of the RT-gels fuse to form giant globules upon heating, which, in turn, resulted in heat-set gelation through further aggregation. The thermoresponsive property of Py-D alone and 1 : 1 Py-D : NDI-A CT complex was investigated in detail which revealed the hydrophobic collapse of the oxyethylene chains of the CT complex upon heating was mainly responsible for heat-set gelation. Thixotropy, injectability, as well as stimuli responsiveness of the RT-gels were also addressed. In contrast, heat-set gel did not show thixotropic behavior. The X-ray diffraction (XRD) patterns of the xerogel depicted lamellar packing of the CT stacks in the gel phase. Single crystal XRD studies further evidenced the 1 : 1 mixed CT stack formation in the lamellae and also ruled out orthogonal hydrogen bonding possibilities among the hydrazide unit in the CT gel although such interaction was observed in a single crystal of NDI-A alone. In addition, a Ag+-ion triggered metallogelation of NDI-A and nematic liquid-crystalline property of Py-D were also observed.The remarkable ability of a charge-transfer (CT) complex prepared from a pyrene-based donor (Py-D) and a naphthalenediimide-based acceptor (NDI-A) led to the formation of a deep-violet in color, transparent hydrogel at room temperature (RT-gel). Simultaneously, the RT-gel was diluted beyond its critical gelator concentration (CGC) to obtain a transparent sol. Very interestingly, the

  7. Cell proliferation and cell sheet detachment from the positively and negatively charged nanocomposite hydrogels.

    PubMed

    Liu, Dan; Wang, Tao; Liu, Xinxing; Tong, Zhen

    2014-01-01

    The charged nanocomposite hydrogels (NC gels) were synthesized by copolymerization of positively or negatively chargeable monomer with N-isopropylacrylamide (NIPAm) in the aqueous suspension of hectorite clay. The ionic NC gels preserved the thermo-responsibility with the phase-transition temperature below 37°C. The L929 cell proliferation was sensitive to charge polarity and charge density. As compared to the PNIPAm NC gel, the cationic NC gels with <5 mol % of 2-(dimethylamino)ethyl methacrylate (DMAEMA) showed improved cell proliferation, whereas the cells grew slowly on the gels with negatively charged 2-acrylamido-2-methylpropane sulfonic acid (AMPSNa). By lowering temperature, rapid cell sheet detachment was observed from the surface of ionic NC gels with 1 mol % of ionizable monomers. However, lager amount of AMPSNa or DMAEMA did not support rapid cell sheet detachment, probably owing to the adverse swelling effects and/or enhanced electrostatic attraction.

  8. First report of charge-transfer induced heat-set hydrogel. Structural insights and remarkable properties.

    PubMed

    Bhattacharjee, Subham; Maiti, Bappa; Bhattacharya, Santanu

    2016-06-01

    The remarkable ability of a charge-transfer (CT) complex prepared from a pyrene-based donor (Py-D) and a naphthalenediimide-based acceptor (NDI-A) led to the formation of a deep-violet in color, transparent hydrogel at room temperature (RT-gel). Simultaneously, the RT-gel was diluted beyond its critical gelator concentration (CGC) to obtain a transparent sol. Very interestingly, the resultant sol, on heating above 70 °C, transformed into a heat-set gel instantaneously with a hitherto unknown CGC value. Detailed studies revealed the smaller globular aggregates of the RT-gels fuse to form giant globules upon heating, which, in turn, resulted in heat-set gelation through further aggregation. The thermoresponsive property of Py-D alone and 1 : 1 Py-D : NDI-A CT complex was investigated in detail which revealed the hydrophobic collapse of the oxyethylene chains of the CT complex upon heating was mainly responsible for heat-set gelation. Thixotropy, injectability, as well as stimuli responsiveness of the RT-gels were also addressed. In contrast, heat-set gel did not show thixotropic behavior. The X-ray diffraction (XRD) patterns of the xerogel depicted lamellar packing of the CT stacks in the gel phase. Single crystal XRD studies further evidenced the 1 : 1 mixed CT stack formation in the lamellae and also ruled out orthogonal hydrogen bonding possibilities among the hydrazide unit in the CT gel although such interaction was observed in a single crystal of NDI-A alone. In addition, a Ag(+)-ion triggered metallogelation of NDI-A and nematic liquid-crystalline property of Py-D were also observed. PMID:27187776

  9. Semiconductor nanoparticle-based hydrogels prepared via self-initiated polymerization under sunlight, even visible light

    PubMed Central

    Zhang, Da; Yang, Jinhu; Bao, Song; Wu, Qingsheng; Wang, Qigang

    2013-01-01

    Since ancient times, people have used photosynthesized wood, bamboo, and cotton as building and clothing materials. The advantages of photo polymerization include the mild and easy process. However, the direct use of available sunlight for the preparation of materials is still a challenge due to its rather dilute intensity. Here, we show that semiconductor nanoparticles can be used for initiating monomer polymerization under sunlight and for cross-linking to form nanocomposite hydrogels with the aid of clay nanosheets. Hydrogels are an emerging multifunctional platform because they can be easily prepared using solar energy, retain semiconductor nanoparticle properties after immobilization, exhibit excellent mechanical strength (maximum compressive strength of 4.153 MPa and tensile strength 1.535 MPa) and high elasticity (maximum elongation of 2784%), and enable recyclable photodegradation of pollutants. This work suggests that functional nanoparticles can be immobilized in hydrogels for their collective application after combining their mechanical and physiochemical properties. PMID:23466566

  10. Preparation and adsorption property of xylan/poly(acrylic acid) magnetic nanocomposite hydrogel adsorbent.

    PubMed

    Sun, Xiao-Feng; Liu, Baichen; Jing, Zhanxin; Wang, Haihong

    2015-03-15

    Adsorbents based on natural polysaccharides have attracted increasing interest because of their low-cost and biodegradability, particularly, polysaccharide-based nanocomposite adsorbents. In this study the xylan/poly(acrylic acid) magnetic nanocomposite hydrogel adsorbent was prepared from wheat straw xylan and Fe3O4 nanoparticles, and its adsorption property was studied on methylene blue removal. The prepared hydrogel adsorbent had a semi-interpenetrating network structure and exhibited a macro-porous structure with interconnected porous channels. Super-paramagnetic characteristic behavior was observed from magnetic analysis using a vibrating sample magnetometer. The optimum condition for methylene blue adsorption on the adsorbent was found at pH 8 with an adsorbent dosage of 3g/L and an initial concentration of 400mg/L, and the removal percentage reached above 90%. The adsorption isotherm of methylene blue on the prepared hydrogel adsorbent was fitted to the Langmuir model, and the pseudo-second-order kinetic model could describe the adsorption process. All obtained results indicated that the prepared hydrogel adsorbent is promising for water treatment applications. PMID:25542101

  11. Dynamic Peptide Library for the Discovery of Charge Transfer Hydrogels.

    PubMed

    Berdugo, Cristina; Nalluri, Siva Krishna Mohan; Javid, Nadeem; Escuder, Beatriu; Miravet, Juan F; Ulijn, Rein V

    2015-11-25

    Coupling of peptide self-assembly to dynamic sequence exchange provides a useful approach for the discovery of self-assembling materials. In here, we demonstrate the discovery and optimization of aqueous, gel-phase nanostructures based on dynamically exchanging peptide sequences that self-select to maximize charge transfer of n-type semiconducting naphthalenediimide (NDI)-dipeptide bioconjugates with various π-electron-rich donors (dialkoxy/hydroxy/amino-naphthalene or pyrene derivatives). These gel-phase peptide libraries are characterized by spectroscopy (UV-vis and fluorescence), microscopy (TEM), HPLC, and oscillatory rheology and it is found that, of the various peptide sequences explored (tyrosine Y-NDI with tyrosine Y, phenylalanine F, leucine L, valine V, alanine A or glycine G-NH2), the optimum sequence is tyrosine-phenylalanine in each case; however, both its absolute and relative yield amplification is dictated by the properties of the donor component, indicating cooperativity of peptide sequence and donor/acceptor pairs in assembly. The methodology provides an in situ discovery tool for nanostructures that enable dynamic interfacing of supramolecular electronics with aqueous (biological) systems. PMID:26540455

  12. Preparation and characterization of nanosized P(NIPAM-MBA) hydrogel particles and adsorption of bovine serum albumin on their surface.

    PubMed

    Zhu, Xiaoli; Gu, Xiangling; Zhang, Lina; Kong, Xiang-Zheng

    2012-09-24

    Thermosensitive polymer hydrogel particles with size varying from 480 to 620 nm were prepared through precipitation copolymerization of N-isopropylacrylamide with N,N'-methylenebisacrylamide (MBA) in water with ammonium persulfate as the initiator. Only polymer hydrogels without any coagula were obtained when MBA concentration in the monomer mixture was kept between 2.5 and 10.0 wt%; with increased MBA concentration, the monomer conversion was enhanced, the size of the hydrogels was increased, and their shrinking was lessened when heated from 25°C to 40°C. Bovine serum albumin adsorption on the surface of the hydrogels of different MBA content was measured at different pH levels and under different temperatures. The results demonstrated that the adsorption of the protein on the hydrogels could be controlled by adjusting the pH, the temperature of adsorption, and the crosslinking in the hydrogels. The results were interpreted, and the mechanisms of the polymerization were proposed.

  13. Preparation and characterization of nanosized P(NIPAM-MBA) hydrogel particles and adsorption of bovine serum albumin on their surface

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoli; Gu, Xiangling; Zhang, Lina; Kong, Xiang-Zheng

    2012-09-01

    Thermosensitive polymer hydrogel particles with size varying from 480 to 620 nm were prepared through precipitation copolymerization of N-isopropylacrylamide with N,N'-methylenebisacrylamide (MBA) in water with ammonium persulfate as the initiator. Only polymer hydrogels without any coagula were obtained when MBA concentration in the monomer mixture was kept between 2.5 and 10.0 wt%; with increased MBA concentration, the monomer conversion was enhanced, the size of the hydrogels was increased, and their shrinking was lessened when heated from 25°C to 40°C. Bovine serum albumin adsorption on the surface of the hydrogels of different MBA content was measured at different pH levels and under different temperatures. The results demonstrated that the adsorption of the protein on the hydrogels could be controlled by adjusting the pH, the temperature of adsorption, and the crosslinking in the hydrogels. The results were interpreted, and the mechanisms of the polymerization were proposed.

  14. Glow discharge electrolysis plasma initiated preparation of temperature/pH dual sensitivity reed hemicellulose-based hydrogels.

    PubMed

    Zhang, Wenming; Zhu, Sha; Bai, Yunping; Xi, Ning; Wang, Shaoyang; Bian, Yang; Li, Xiaowei; Zhang, Yucang

    2015-05-20

    The temperature/pH dual sensitivity reed hemicellulose-based hydrogels have been prepared through glow discharge electrolysis plasma (GDEP). The effect of different discharge voltages on the temperature and pH response performance of reed hemicellulose-based hydrogels was inspected, and the formation mechanism, deswelling behaviors of reed hemicellulose-based hydrogels were also discussed. At the same time, infrared spectroscopy (FT-IR), scanning differential thermal analysis (DSC) and scanning electron microscope (SEM) were adopted to characterize the structure, phase transformation behaviors and microstructure of hydrogels. It turned out to be that all reed hemicellulose-based hydrogels had a double sensitivity to temperature and pH, and their phase transition temperatures were all approximately 33 °C, as well as the deswelling dynamics met the first model. In addition, the hydrogel (TPRH-3), under discharge voltage 600 V, was more sensitive to temperature and pH and had higher deswelling ratio.

  15. Glow discharge electrolysis plasma initiated preparation of temperature/pH dual sensitivity reed hemicellulose-based hydrogels.

    PubMed

    Zhang, Wenming; Zhu, Sha; Bai, Yunping; Xi, Ning; Wang, Shaoyang; Bian, Yang; Li, Xiaowei; Zhang, Yucang

    2015-05-20

    The temperature/pH dual sensitivity reed hemicellulose-based hydrogels have been prepared through glow discharge electrolysis plasma (GDEP). The effect of different discharge voltages on the temperature and pH response performance of reed hemicellulose-based hydrogels was inspected, and the formation mechanism, deswelling behaviors of reed hemicellulose-based hydrogels were also discussed. At the same time, infrared spectroscopy (FT-IR), scanning differential thermal analysis (DSC) and scanning electron microscope (SEM) were adopted to characterize the structure, phase transformation behaviors and microstructure of hydrogels. It turned out to be that all reed hemicellulose-based hydrogels had a double sensitivity to temperature and pH, and their phase transition temperatures were all approximately 33 °C, as well as the deswelling dynamics met the first model. In addition, the hydrogel (TPRH-3), under discharge voltage 600 V, was more sensitive to temperature and pH and had higher deswelling ratio. PMID:25817637

  16. Preparation and characterization of chitin hydrogels by water vapor induced gelation route.

    PubMed

    Vachoud, L; Pochat-Bohatier, C; Chakrabandhu, Y; Bouyer, D; David, L

    2012-11-01

    A novel method of chitin hydrogel preparation, called vapor induced gelation, using exposure of chitin/N-methyl-pyrrolidone/LiCl solution to water vapors is presented. Compared to gelation induced by direct immersion in water, hydrogels are characterized by smaller deformation during gelation (area shrinkage is 20% instead of 65%), larger water volume fraction (75 instead of 62%, v/v) and 10 times higher apparent compression moduli. Their nanostructure consists of thicker and larger crystalline platelets network (thickness=37 Å, apparent coherent crystalline size L₀₂₀=145 Å) comparatively to direct immersion gels (25 Å and L₀₂₀=95 Å). Drug delivery potential of chitin hydrogels was determined for non-interactive low molecular molecules. PMID:22676995

  17. Chitosan-based hydrogel for dye removal from aqueous solutions: Optimization of the preparation procedure

    NASA Astrophysics Data System (ADS)

    Gioiella, Lucia; Altobelli, Rosaria; de Luna, Martina Salzano; Filippone, Giovanni

    2016-05-01

    The efficacy of chitosan-based hydrogels in the removal of dyes from aqueous solutions has been investigated as a function of different parameters. Hydrogels were obtained by gelation of chitosan with a non-toxic gelling agent based on an aqueous basic solution. The preparation procedure has been optimized in terms of chitosan concentration in the starting solution, gelling agent concentration and chitosan-to-gelling agent ratio. The goal is to properly select the material- and process-related parameters in order to optimize the performances of the chitosan-based dye adsorbent. First, the influence of such factors on the gelling process has been studied from a kinetic point of view. Then, the effects on the adsorption capacity and kinetics of the chitosan hydrogels obtained in different conditions have been investigated. A common food dye (Indigo Carmine) has been used for this purpose. Noticeably, although the disk-shaped hydrogels are in the bulk form, their adsorption capacity is comparable to that reported in the literature for films and beads. In addition, the bulk samples can be easily separated from the liquid phase after the adsorption process, which is highly attractive from a practical point of view. Compression tests reveal that the samples do not breakup even after relatively large compressive strains. The obtained results suggest that the fine tuning of the process parameters allows the production of mechanical resistant and highly adsorbing chitosan-based hydrogels.

  18. Photoclick Hydrogels Prepared from Functionalized Cyclodextrin and Poly(ethylene glycol) for Drug Delivery and in Situ Cell Encapsulation.

    PubMed

    Shih, Han; Lin, Chien-Chi

    2015-07-13

    Polymers or hydrogels containing modified cyclodextrin (CD) are highly useful in drug delivery applications, as CD is a cytocompatible amphiphilic molecule that can complex with a variety of hydrophobic drugs. Here, we designed modular photoclick thiol-ene hydrogels from derivatives of βCD and poly(ethylene glycol) (PEG), including βCD-allylether (βCD-AE), βCD-thiol (βCD-SH), PEG-thiol (PEGSH), and PEG-norbornene (PEGNB). Two types of CD-PEG hybrid hydrogels were prepared using radical-mediated thiol-ene photoclick reactions. Specifically, thiol-allylether hydrogels were formed by reacting multiarm PEGSH and βCD-AE, and thiol-norbornene hydrogels were formed by cross-linking βCD-SH and multiarm PEGNB. We characterized the properties of these two types of thiol-ene hydrogels, including gelation kinetics, gel fractions, hydrolytic stability, and cytocompatibility. Compared with thiol-allylether hydrogels, thiol-norbornene photoclick reaction formed hydrogels with faster gelation kinetics at equivalent macromer contents. Using curcumin, an anti-inflammatory and anticancer hydrophobic molecule, we demonstrated that CD-cross-linked PEG-based hydrogels, when compared with pure PEG-based hydrogels, afforded higher drug loading efficiency and prolonged delivery in vitro. Cytocompatibility of these CD-cross-linked hydrogels were evaluated by in situ encapsulation of radical sensitive pancreatic MIN6 β-cells. All formulations and cross-linking conditions tested were cytocompatible for cell encapsulation. Furthermore, hydrogels cross-linked by βCD-SH showed enhanced cell proliferation and insulin secretion as compared to gels cross-linked by either dithiothreitol (DTT) or βCD-AE, suggesting the profound impact of both macromer compositions and gelation chemistry on cell fate in chemically cross-linked hydrogels. PMID:25996903

  19. Preparation, characterization, and biocompatibility evaluation of poly(Nɛ-acryloyl-L-lysine)/hyaluronic acid interpenetrating network hydrogels.

    PubMed

    Cui, Ning; Qian, Junmin; Xu, Weijun; Xu, Minghui; Zhao, Na; Liu, Ting; Wang, Hongjie

    2016-01-20

    In the present study, poly(Nɛ-acryloyl-L-lysine)/hyaluronic acid (pLysAAm/HA) interpenetrating network (IPN) hydrogels were successfully fabricated through the combination of hydrazone bond crosslinking and photo-crosslinking reactions. The HA hydrogel network was first synthesized from 3,3'-dithiodipropionate hydrazide-modified HA and polyethylene glycol dilevulinate by hydrazone bond crosslinking. The pLysAAm hydrogel network was prepared from Nɛ-acryloyl-L-lysine and N,N'-bis(acryloyl)-(L)-cystine by photo-crosslinking. The resultant pLysAAm/HA hydrogels had a good shape recovery property after loading and unloading for 1.5 cycles (up to 90%) and displayed a highly porous microstructure. Their compressive moduli were at least 5 times higher than that of HA hydrogels. The pLysAAm/HA hydrogels had an equilibrium swelling ratio of up to 37.9 and displayed a glutathione-responsive degradation behavior. The results from in vitro biocompatibility evaluation with pre-osteoblasts MC3T3-E1 cells revealed that the pLysAAm/HA hydrogels could support cell viability and proliferation. Hematoxylin and eosin staining indicated that the pLysAAm/HA hydrogels allowed cell and tissue infiltration, confirming their good in vivo biocompatibility. Therefore, the novel pLysAAm/HA IPN hydrogels have great potential for bone tissue engineering applications.

  20. Combined Skin Moisturization of Liposomal Serine Incorporated in Hydrogels Prepared with Carbopol ETD 2020, Rhesperse RM 100 and Hyaluronic Acid

    PubMed Central

    Kim, Hyeongmin; Ro, Jieun; Barua, Sonia; Hwang, Deuk Sun; Na, Seon-Jeong; Lee, Ho Sung; Jeong, Ji Hoon; Woo, Seulki; Kim, Hyewon; Hong, Bomi; Yun, Gyiae; Kim, Joong-Hark; Yoon, Young-Ho; Park, Myung-Gyu; Kim, Jia; Sohn, Uy Dong

    2015-01-01

    We investigated the combined moisturizing effect of liposomal serine and a cosmeceutical base selected in this study. Serine is a major amino acid consisting of natural moisturizing factors and keratin, and the hydroxyl group of serine can actively interact with water molecules. Therefore, we hypothesized that serine efficiently delivered to the stratum corneum (SC) of the skin would enhance the moisturizing capability of the skin. We prepared four different cosmeceutical bases (hydrogel, oil-in-water (O/W) essence, O/W cream, and water-in-oil (W/O) cream); their moisturizing abilities were then assessed using a Corneometer®. The hydrogel was selected as the optimum base for skin moisturization based on the area under the moisture content change-time curves (AUMCC) values used as a parameter for the water hold capacity of the skin. Liposomal serine prepared by a reverse-phase evaporation method was then incorporated in the hydrogel. The liposomal serine-incorporated hydrogel (serine level=1%) showed an approximately 1.62~1.77 times greater moisturizing effect on the skin than those of hydrogel, hydrogel with serine (1%), and hydrogel with blank liposome. However, the AUMCC values were not dependent on the level of serine in liposomal serine-loaded hydrogels. Together, the delivery of serine to the SC of the skin is a promising strategy for moisturizing the skin. This study is expected to be an important step in developing highly effective moisturizing cosmeceutical products. PMID:26557021

  1. Sodium hydroxide-mediated hydrogel of citrus pectin for preparation of fluorescent carbon dots for bioimaging.

    PubMed

    Zhao, Xi Juan; Zhang, Wen Lin; Zhou, Zhi Qin

    2014-11-01

    The citrus process industry produces annually a huge amount of pomace, which is a rich source of citrus pectin. Here, we report the hydrogel of citrus pectin mediated by sodium hydroxide can be used to prepare fluorescent carbon dots (CDs). The introduction of hydrogel can not only make the temperature of the hydrothermal reaction down to 100 °C, but also avoid visually carbonized precipitates in the synthesis process even up to 180 °C. The as-synthesized CDs are well dispersed in water with an average size of 2.7 nm and show cyan fluorescence with high photostability, good biocompatibility. Furthermore, the CDs can act as a potential fluorescent probe for cell imaging. Citrus pectin as a non-toxic carbonaceous precursor for preparation of fluorescent CDs provides a new approach for the efficient utilization of citrus germplasm in future.

  2. A new method for the preparation of biomedical hydrogels comprised of extracellular matrix and oligourethanes.

    PubMed

    Claudio-Rizo, Jesús A; Mendoza-Novelo, Birzabith; Delgado, Jorge; Castellano, Laura E; Mata-Mata, José L

    2016-01-01

    This paper reports a new method to modify hydrogels derived from the acellular extracellular matrix (ECM) and consequently to improve their properties. The method is comprised of the combination of liquid precursors derived from hydrolyzed acellular small intestinal submucosa (hECM) and water-soluble oligourethanes that bear protected isocyanate groups, synthesized from poly(ethylene glycol) (PEG) and hexamethylene diisocyanate (HDI). The results demonstrate that the reactivity of oligourethanes, along with their water solubility, properly induce simultaneously the polymerization of type I collagen and its crosslinking. The polymerization rate and the gel network parameters such as fiber diameter, porosity, crosslinking degree, mechanics, swelling, in vitro degradation and cell proliferation, keep a direct relationship with the oligourethane concentration. Consequently, the hybrid hydrogels formulated with 15 wt.% of oligourethane exhibit enhanced storage modulus and degradation resistance, while maintaining the cell viability and impeding the fibroblast-induced contraction in comparison with the hECM hydrogels without oligourethanes. Therefore, this method is adequate to prepare novel hydrogels where the adjustment of the crosslinking degree controls the materials structure and their properties. This new method offers advantages for regulating the features of ECM-derived templates, thereby extending their possibilities for tissue engineering (TE) applications. PMID:27305317

  3. Multi stimuli-responsive hydrogel microfibers containing magnetite nanoparticles prepared using microcapillary devices.

    PubMed

    Lim, Daeun; Lee, Eunsu; Kim, Haneul; Park, Sungmin; Baek, Seulgi; Yoon, Jinhwan

    2015-02-28

    Extensive research efforts have been devoted to the development of hydrogel microfibers for tissue engineering, because the vascular structure is related to the transport of nutrients and oxygen as well as the control of metabolic and mechanical functions in the human body. Even though stimuli-responsive properties would enhance the potential applicability of hydrogel microfibers for artificial tissue architectures, previous studies of their fabrication have not considered changes in the microfibers in response to external stimuli. In this work, we prepared temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) microfibers with controlled shapes and sizes by the in situ photo-polymerization of aqueous monomers loaded in calcium alginate templates generated from microcapillary devices. We found that the shape and size of the hydrogel microfibers could be controlled by adjusting the injection positions of the solutions and varying the diameters of the inner capillary, respectively. We further fabricated light-responsive materials by incorporating photothermal magnetite nanoparticles (MNPs) within the temperature-responsive PNIPAm hydrogel microfibers. Because the MNPs incorporated into the PNIPAm microfibers generated heat upon the absorption of visible light, we could demonstrate volume changes in the microfibers triggered by both visible light irradiation and temperature. PMID:25594916

  4. Multi stimuli-responsive hydrogel microfibers containing magnetite nanoparticles prepared using microcapillary devices.

    PubMed

    Lim, Daeun; Lee, Eunsu; Kim, Haneul; Park, Sungmin; Baek, Seulgi; Yoon, Jinhwan

    2015-02-28

    Extensive research efforts have been devoted to the development of hydrogel microfibers for tissue engineering, because the vascular structure is related to the transport of nutrients and oxygen as well as the control of metabolic and mechanical functions in the human body. Even though stimuli-responsive properties would enhance the potential applicability of hydrogel microfibers for artificial tissue architectures, previous studies of their fabrication have not considered changes in the microfibers in response to external stimuli. In this work, we prepared temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) microfibers with controlled shapes and sizes by the in situ photo-polymerization of aqueous monomers loaded in calcium alginate templates generated from microcapillary devices. We found that the shape and size of the hydrogel microfibers could be controlled by adjusting the injection positions of the solutions and varying the diameters of the inner capillary, respectively. We further fabricated light-responsive materials by incorporating photothermal magnetite nanoparticles (MNPs) within the temperature-responsive PNIPAm hydrogel microfibers. Because the MNPs incorporated into the PNIPAm microfibers generated heat upon the absorption of visible light, we could demonstrate volume changes in the microfibers triggered by both visible light irradiation and temperature.

  5. Preparation and characterization of IPN hydrogels composed of chitosan and gelatin cross-linked by genipin.

    PubMed

    Cui, Li; Jia, Junfang; Guo, Yi; Liu, Yun; Zhu, Ping

    2014-01-01

    The interpenetrating polymer networks (IPN) hydrogels based on chitosan and gelatin using genipin as the cross-linker were prepared and characterized. The IPN formation of the genipin-cross-linked chitosan/gelatin hydrogel was confirmed by means of the instrinsic viscosity measurement, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and the ninhydrin assays. The instrinsic viscosity measurement, FT-IR and SEM suggested that chitosan and gelatin were miscible in the molecular level. The miscibility leads to the formation of IPN after cross-linking. FT-IR also examined the cross-linking mechanism of genipin with primary amino groups. The degree of cross-linking increased with increase genipin concentration. Swelling results revealed that the IPN hydrogels are pH-sensitive, exhibiting reversibility and rather rapidly response in swelling to pH changes. It is expected this IPN hydrogel has potential as controlled drug delivery system or as alternative sorbents for biomedical and environmental use as pH altered. PMID:24274476

  6. Preparation of biocompatible, UV-cured fumarated poly(ether-ester)-based tissue-engineering hydrogels.

    PubMed

    Akdemir, Z Seden; Kayaman-Apohan, Nilhan; Kahraman, M Vezir; Kuruca, Serap Erdem; Güngör, Atilla; Karadenizli, Sabriye

    2011-01-01

    The aim of this study was to develop biodegradable, photo-polymerizable in situ gel-forming systems prepared from a fumaric acid monoethyl ester (FAME) modified poly(lactide-co-glycolide) (PLGA) co-polymer. By reacting lactide and glycolide in the presence of stannous octoate as a catalyst and 2-ethyl,2-hydroxymethyl 1,3-propanediol as an initiator, hydroxyl terminated branched PLGA was synthesized. Afterwards, at room temperature hydroxyl terminated branched PLGA was reacted with fumaric acid monoethyl ester (FAME). N,N'-dicyclohexylcarbodiimide and triethylamine were used as a coupling agent and catalyst, respectively. The gel percentage, equilibrium mass swelling, degradation profile and polymerization kinetics of the hydrogels were investigated. All of the results were influenced by the amount of FAME modified PLGA co-polymer. Biocompatibility of the hydrogels was examined by using MTT cytotoxicity assay. According to the results, hydrogels are biocompatible and cell viability percentage depends on the amount of PLGA co-polymer. While the amount was 15% in hydrogel composition, cell viability was 100%, but after increasing the PLGA co-polymer amount to 30% the viability reduced to 78%. PMID:20566062

  7. Charge and Sequence Effects on the Self-assembly and Subsequent Hydrogelation of Fmoc-Depsipeptides

    PubMed Central

    Nguyen, Mary M.; Eckes, Kevin M.

    2014-01-01

    Herein we report on the self-assembly of a family of Fmoc-depsipeptides into nanofibers and hydrogels. We show that fiber formation occurs in depsipeptide structures in which the fluorenyl group is closely associated and that side-chain charge and sequence affect the extent of self-assembly and subsequent gelation. Using fluorescence emission spectroscopy and circular dichroism, we show that self-assembly can be monitored and is observed in these slow-gelling systems prior to hydrogel formation. We also demonstrate that the ionic strength of salt-containing solutions affects the time at which self-assembly results in gelation of the bulk solution. From transmission electron microscopy, we report that morphological changes progress over time and are observed as micelles transitioning to fibers prior to the onset of gelation. Gelled depsipeptides degraded at a slower rate than non-gelled samples in the presence of salt, while hydrolysis in water of both gels and solution samples was minimal even after 14 days. Our work shows that while incorporating ester functionality within a peptide backbone reduces the number of hydrogen bonding sites available for forming and stabilizing supramolecular assemblies, the substitution does not prohibit self-assembly and subsequent gelation. PMID:24647784

  8. Ionic osmolytes and intracellular calcium regulate tissue production in chondrocytes cultured in a 3D charged hydrogel.

    PubMed

    Farnsworth, Nikki L; Mead, Benjamin E; Antunez, Lorena R; Palmer, Amy E; Bryant, Stephanie J

    2014-11-01

    The goal of this study was to investigate the role of fixed negative charges in regulating cartilage-like tissue production by chondrocytes under static and dynamic three-dimensional culture, and to determine whether intracellular calcium ([Ca(2+)]i) is involved in mediating this response. Initial experiments using the 3D neutral hydrogel were conducted in static isotonic culture with ionic and non-ionic osmolytes added to the culture medium. Tissue production by bovine chondrocytes with non-ionic osmolytes was 1.9-fold greater than with ionic osmolytes, suggesting that the ionic nature of the osmolyte is an important regulator of tissue production. To investigate fixed negative charges, a 3D culture system containing encapsulated chondrocytes was employed based on a synthetic and neutral hydrogel platform within which negatively charged chondroitin sulfate was incorporated in a controlled manner. Incorporation of negative charges did not affect the mechanical properties of the hydrogel; however, intracellular ion concentration was elevated from the culture medium (330 mOsm) and estimated to be similar to that in ~400 mOsm culture medium. With dynamic loading, GAG synthesis decreased by 26% in neutral hydrogels cultured in 400mOsm medium, and increased by 26% in charged gels cultured in 330 mOsm. Treatment of chondrocyte-seeded hydrogels with the Ca(2+) chelator BAPTA-AM decreased GAG synthesis by 32-46% and was similar among all conditions, suggesting multiple roles for Ca(2+) mediated tissue production including with ionic osmolytes. In conclusion, findings from this study suggest that a dynamic ionic environment regulates tissue synthesis and points to [Ca(2+)]i signaling as a potential mediator. PMID:25128592

  9. Microscale solution manipulation using photopolymerized hydrogel membranes and induced charge electroosmosis micropumps

    NASA Astrophysics Data System (ADS)

    Paustian, Joel Scott

    Microfluidic technology is playing an ever-expanding role in advanced chemical and biological devices, with diverse applications including medical diagnostics, high throughput research tools, chemical or biological detection, separations, and controlled particle fabrication. Even so, local (microscale) modification of solution properties within microchannels, such as pressure, solute concentration, and voltage remains a challenge, and improved spatiotemporal control would greatly enhance the capabilities of microfluidics. This thesis demonstrates and characterizes two microfluidic tools to enhance local solution control. I first describe a microfluidic pump that uses an electrokinetic effect, Induced-Charge Electroosmosis (ICEO), to generate pressure on-chip. In ICEO, steady flows are driven by AC fields along metal-electrolyte interfaces. I design and microfabricate a pump that exploits this effect to generate on-chip pressures. The ICEO pump is used to drive flow along a microchannel, and the pressure is measured as a function of voltage, frequency, and electrolyte composition. This is the first demonstration of chip-scale flows driven by ICEO, which opens the possibility for ICEO pumping in self-contained microfluidic devices. Next, I demonstrate a method to create thin local membranes between microchannels, which enables local diffusive delivery of solute. These ``Hydrogel Membrane Microwindows'' are made by photopolymerizing a hydrogel which serves as a local ``window'' for solute diffusion and electromigration between channels, but remains a barrier to flow. I demonstrate three novel experimental capabilities enabled by the hydrogel membranes: local concentration gradients, local electric currents, and rapid diffusive composition changes. I conclude by applying the hydrogel membranes to study solvophoresis, the migration of particles in solvent gradients. Solvent gradients are present in many chemical processes, but migration of particles within these

  10. Low viscosity hydrogel of guar gum: preparation and physicochemical characterization.

    PubMed

    Cunha, Pablyana L R; Castro, Rondinelle R; Rocha, Francisco A C; de Paula, Regina C M; Feitosa, Judith P A

    2005-10-30

    Guar gum was cross-linked with glutaraldehyde and characterized by GPC, rheology, WADX, SEM and TGA. This guar gum is a galactomannan polysaccharide, that contains small amount of arabinose, glucose and uronic acid, besides galactose and mannose. The polymer has high molar mass, with Mw, Mn and Mv values of 2.0x10(6), 1.2x10(6) and 1.9x10(6)g/mol, respectively. The reticulation follows a slow process and lead to a viscosity increase of 40 times compared with the original gum solution. The final viscosity was similar to that of Hylan G-F 20, a hyaluronate derivative, commercially used in viscosupplementation treatment. The gel contains 95.6% of water and the amount of residual glutaraldehyde is much lower than the LD-50. Porous structure was detected by SEM and thermal stability was improved by the cross-linking. The low viscosity, the small amount of remained glutaraldehyde, and the thermal stability indicates that the guar hydrogel has potential to be applied as biomaterial with specific rheological requirements. PMID:16221491

  11. Off-line sample preparation by electrophoretic concentration using a micropipette and hydrogel.

    PubMed

    Wuethrich, Alain; Haddad, Paul R; Quirino, Joselito P

    2014-11-21

    An off-line electrophoretic sample concentration technique for charged analytes in aqueous samples is presented. As a demonstration, nine anions including inorganic ions, a dye and benzenesulfonate derivatives were enriched from a 10 mL sample solution into 20 μL electrolyte inside a glass micropipette. A hydrogel was placed at one end of the micropipette while the other end was immersed in the sample. The electric field caused the movement and concentration of anions into the high conductivity electrolyte. The technique was applied to purified, drinking and river water and was optimised by changing applied voltage and voltage application time. The LODs after analysis by capillary electrophoresis was 1-19 ng/mL, 4-133 ng/mL and 18-80 ng/mL for purified, drinking and river water, respectively. The linear range was 0.002-0.048 to 0.1-2.4 μg/mL (R(2) of 0.993-0.999), 0.02-0.24 to 1.0-24 μg/mL (R(2) of 0.995-0.999) and 0.02-0.24 to 1.0-24 μg/mL (R(2) of 0.998-1.000), correspondingly. The intraday and interday repeatability (%RSD, n=6) was ≤7.4% and 14.0%, respectively. The concentration factor was from one to two orders of magnitude. The technique was directly compatible with a liquid phase analytical technique, thus eliminated the additional steps (e.g., evaporation, elution and/or reconstitution) which are typically performed in sample preparation (e.g., liquid and solid phase extraction). PMID:25441086

  12. Preparation and properties of graphene oxide-regenerated cellulose/polyvinyl alcohol hydrogel with pH-sensitive behavior.

    PubMed

    Rui-Hong, Xie; Peng-Gang, Ren; Jian, Hui; Fang, Ren; Lian-Zhen, Ren; Zhen-Feng, Sun

    2016-03-15

    In this study, graphene oxide reinforced regenerated cellulose/polyvinyl alcohol (GO-RCE/PVA) ternary hydrogels were successfully prepared via a repeated freezing and thawing method in NaOH/urea aqueous solution. The effect of GO content on the mechanical properties, swelling behavior, water content of composite hydrogels was investigated. It was found that the mechanical properties of GO-RCE/PVA ternary hydrogels were largely enhanced relative to RCE/PVA hydrogels. With the addition of 1.0wt% GO, the tensile strength was increased by 40.4% from 0.52MPa to 0.73MPa, accompanied by the increase of the elongation at break (from 103% to 238%). Meanwhile, GO-RCE/PVA ternary hydrogels performed the excellent pH-sensitivity, and the higher pH leaded to higher swelling ratio. With 0.8wt% GO loading, the swelling ratio of GO-RCE/PVA ternary hydrogel was improved from 150% (pH=2) to 310% (pH=14). In addition, a slight increase in the water content of the ternary hydrogel was achieved with increasing concentrations of GO. It is believed that this novel ternary hydrogels is a promising material in the application of biomedical engineering and intelligent devices. PMID:26794756

  13. Preparation and properties of graphene oxide-regenerated cellulose/polyvinyl alcohol hydrogel with pH-sensitive behavior.

    PubMed

    Rui-Hong, Xie; Peng-Gang, Ren; Jian, Hui; Fang, Ren; Lian-Zhen, Ren; Zhen-Feng, Sun

    2016-03-15

    In this study, graphene oxide reinforced regenerated cellulose/polyvinyl alcohol (GO-RCE/PVA) ternary hydrogels were successfully prepared via a repeated freezing and thawing method in NaOH/urea aqueous solution. The effect of GO content on the mechanical properties, swelling behavior, water content of composite hydrogels was investigated. It was found that the mechanical properties of GO-RCE/PVA ternary hydrogels were largely enhanced relative to RCE/PVA hydrogels. With the addition of 1.0wt% GO, the tensile strength was increased by 40.4% from 0.52MPa to 0.73MPa, accompanied by the increase of the elongation at break (from 103% to 238%). Meanwhile, GO-RCE/PVA ternary hydrogels performed the excellent pH-sensitivity, and the higher pH leaded to higher swelling ratio. With 0.8wt% GO loading, the swelling ratio of GO-RCE/PVA ternary hydrogel was improved from 150% (pH=2) to 310% (pH=14). In addition, a slight increase in the water content of the ternary hydrogel was achieved with increasing concentrations of GO. It is believed that this novel ternary hydrogels is a promising material in the application of biomedical engineering and intelligent devices.

  14. Polyvinyl pyrrolidone/carrageenan blend hydrogels with nanosilver prepared by gamma radiation for use as an antimicrobial wound dressing.

    PubMed

    Singh, Durgeshwer; Singh, Antaryami; Singh, Rita

    2015-01-01

    Hydrogels were prepared using polyvinyl pyrrolidone (PVP) blended with carrageenan by gamma irradiation at different doses of 25 and 40 kGy. Gel fraction of hydrogels prepared using 10 and 15% PVP in combination with 0.25 and 0.5% carrageenan was evaluated. Based on gel fraction, 15% PVP in combination with 0.25% carrageenan and radiation dose of 25 kGy was selected for the preparation of hydrogels with nanosilver. Radiolytic synthesis of silver nanoparticles within the PVP hydrogel was carried out. The hydrogels with silver nanoparticles were assessed for antimicrobial effectiveness and physical properties of relevance to clinical performance. Fluid handling capacity (FHC) for PVP/carrageenan was 2.35 ± 0.39-6.63 ± 0.63 g/10 cm(2) in 2-24 h. No counts for Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Candida albicans were observed in the presence of hydrogels containing 100 ppm nanosilver after 3-6 h. The release of silver from hydrogels containing 100 ppm nanosilver was 20.42 ± 1.98 ppm/100 cm(2) in 24 h. Hydrogels containing 100 ppm nanosilver with efficient FHC demonstrated potential microbicidal activity (≥3 log10 decrease in CFU/ml) against wound pathogens, P. aeruginosa, S. aureus, E. coli, and C. albicans. PVP/carrageenan hydrogels containing silver nanoparticles can be used as wound dressings to control infection and facilitate the healing process for burns and other skin injuries.

  15. Vascular-like network prepared using hollow hydrogel microfibers.

    PubMed

    Takei, Takayuki; Kitazono, Zyunpei; Ozuno, Yoshihiro; Yoshinaga, Takuma; Nishimata, Hiroto; Yoshida, Masahiro

    2016-03-01

    One major challenge in the field of tissue engineering was the creation of volumetric tissues and organs in vitro. To achieve this goal, the development of a three-dimensional vascular-like network that extended throughout the tissue-engineered construct was essential to supply sufficient oxygen and nutrients to all of the cells in the constructs. For sufficient oxygenation and nutrition of the tissue-engineered constructs, the distance between each microvessel-like channel in the network should ideally be within 100-200 μm. In addition, the medium or blood should be perfused through the microchannels as soon as possible after the seeding of cells into the templates (scaffolds) of the constructs. In the present study, we proposed a novel technique for fabricating an engineered vascular-like network that satisfied these two requirements. The network comprised assembled hollow alginate hydrogel microfibers with mammalian cells enclosed in the gel portions. We controlled the distance between each flow microchannel (hollow core portions and interspace of the microfibers) to be within 150 μm by using microfibers with a gel thickness of approximately 50 μm. Furthermore, we confirmed that medium could be perfused into the flow channels quickly (within 10 min) after immobilization of the cells in the assembly. A human hepatoblastoma cell line (HepG2) proliferated in the gel portions of the microfibers and maintained their specific function during perfusion culture for 7 days. These results showed that the novel vascular-like networks fabricated here had the potential to allow the creation of volumetric tissues in vitro. PMID:26199226

  16. Preparation of hydrogels for atopic dermatitis containing natural herbal extracts by gamma-ray irradiation

    NASA Astrophysics Data System (ADS)

    Lim, Youn-Mook; An, Sung-Jun; Kim, Hae-Kyoung; Kim, Yun-Hye; Youn, Min-Ho; Gwon, Hui-Jeong; Shin, Junhwa; Nho, Young-Chang

    2009-07-01

    Atopic dermatitis (AD) is a familial and chronic inflammatory pruritic skin disease that affects a large number of children and adults in industrialized countries. It is known that one of the prominent features of AD and chronic pruritus is partially due to the histamine released from mast cell. In this work, hydrogel patches with natural herbal extracts were prepared by "freezing and thawing", and a gamma irradiation. It showed eminent healing results as a consequence of long-term moisturizing effects and natural herbal extracts on atopic wounds. Besides its non-toxicity and human harmlessness, it can be easily attached to or detached from the skin without any trace and help patients to feel refreshment when attached. Based on this work, the hydrogel patches we made can be potentially used as an alternative remedy for not only pruritus in AD, but other dermatitis.

  17. β-Chitin nanofibrils for self-sustaining hydrogels preparation via hydrothermal treatment.

    PubMed

    Nata, Iryanti Fatyasari; Wang, Steven Sheng-Shih; Wu, Tsai-Mao; Lee, Cheng-Kang

    2012-11-01

    A transparent nanofibril suspension could be readily obtained by treating purified squid pen powder in water with ultrasonic irradiation. The obtained suspension is consisted of β-chitin nanofibrils (CNF) with 3-10 nm in width and several micrometers in length. The degree of acetylation (DA) of CNF was found to be 84% which is about 10% lower than that of untreated sample. The CNF suspension could be transformed into a durable 3-D hydrogels (CH) by simply heating to 180 °C for 1-4 h in an autoclave. Hydrophobic interaction between CNF was believed to play the major role for CNF self-assembling into hydrogels, since the as-prepared chitin hydrogels readily dissolved in a typical chaotropic solution (8 M urea) under room temperature. The hydrothermal duration and CNF concentration (0.3-2% (w/v)) strongly affected the physical properties of CH. The suspension of 1% (w/v) CNF treated with 4 h, 180 °C hydrothermal heating generated a CH with 99.3% water content, CNF with 87% crystallinity and an mechanical strength of 0.7 N breaking force.

  18. Characterization of pH-Responsive Hydrogels of Poly(Itaconic acid-g-Ethylene Glycol) Prepared by UV-Initiated Free Radical Polymerization as Biomaterials for Oral Delivery of Bioactive Agents

    PubMed Central

    Betancourt, Tania; Pardo, Juan; Soo, Ken; Peppas, Nicholas A.

    2009-01-01

    Effective oral delivery of proteins is impeded by steep pH gradients and proteolytic enzymes in the gastrointestinal tract, as well as low absorption of the proteins into the bloodstream due to their size, charge or solubility. In the present work, pH-responsive complexation hydrogels of poly(itaconic acid) with poly(ethylene glycol) grafts were synthesized for applications in oral drug delivery. These hydrogels were expected to be in collapsed configuration at low pH due to hydrogen bonding between poly(itaconic acid) carboxyl groups and poly(ethylene glycol), and to swell with increasing pH because of charge repulsion between deprotonated carboxylic acid groups. Hydrogels were prepared by UV-initiated free radical polymerization using tetraethylene glycol as the crosslinking agent and Irgacure® 2959 as the initiator. The effect of monomer ratios, crosslinking ratio and solvent amount on the properties of the hydrogels were investigated. The composition of the hydrogels was confirmed by FTIR. Equilibrium swelling studies in the pH range of 1.2 to 7 revealed that the extent of swelling increased with increasing pH up to a pH of about 6, when no further carboxylic acid deprotonation occurred. Studies in Caco-2 colorectal carcinoma cells confirmed the cytocompatibility of these materials at concentrations of up to 5 mg/ml. PMID:19536838

  19. Application of hydrogel prepared from ferrocene functionalized amino acid in the design of novel electrochemical immunosensing platform.

    PubMed

    Zhou, Miao; Sun, Zhifang; Shen, Congcong; Li, Zhengyuan; Zhang, Yi; Yang, Minghui

    2013-11-15

    A simple and novel supramolecular hydrogel was prepared from ferrocene (Fc) modified amino acid phenylalanine (F) and utilized as electrochemical immunosensing platform for the detection of human IgG. Scanning electron microscopy (SEM) characterization indicated that the hydrogel is composed of fibrils with diameter around 50-100 nm and length extend to 1mm. When the prepared hydrogel was reacted with H2O2, the Fc moieties on the amino acid was oxidized, leading to the disruption of the hydrogel structure and the decrease of its redox signal, which was characterized in detail by SEM and the electrochemical method. Regarding the redox current decrease upon the reaction of the hydrogel with H2O2, the hydrogel modified electrode was utilized as immunosensing interface. After the construction of the immunosensor based on the traditional sandwich protocol with glucose oxidase (GOx) functionalized carbon nanotube (CNT) as detection antibody label, the GOx attached onto electrode surface would catalyze glucose reaction to produce H2O2 and cause the decrease of redox current of the electrode. The current change is proportional to the concentration of IgG detected in the range from 0.1 to 100 pg/mL. The high sensitivity, wide linear range and good reproducibility of the immunosensor indicate this immunosensing platform can be easily extended to the detection of other protein biomarkers.

  20. Preparation of γ-aminopropyltriethoxysilane cross-linked poly(aspartic acid) superabsorbent hydrogels without organic solvent.

    PubMed

    Meng, Hongyu; Zhang, Xin; Sun, Shenyu; Tan, Tianwei; Cao, Hui

    2016-01-01

    Poly(aspartic acid) (PASP) hydrogel is a type of biodegradable and biocompatible polymer with high water absorbing ability. Traditionally, the production of PASP hydrogel is expensive, complex, environmentally unfriendly, and consumes a large amount of organic solvents, e.g. dimethylformamide or dimethylsulfoxide. This study introduces a one-step synthesis of PASP resin, in which the organic phase was replaced by distilled water and γ-aminopropyltriethoxysilane was used as the cross-linker. Absorbent ability and characteristics were determined by swelling ratio, FTIR, (13)C SSNMR, and SEM. In vitro cytotoxicity evaluation and animal skin irritation tests showed the hydrogel has body-friendly properties. Preparing PASP hydrogel in aqueous solution is promising and finds its use in many applications. PMID:26499167

  1. Oppositely charged polyelectrolytes form tough, self-healing, and rebuildable hydrogels.

    PubMed

    Luo, Feng; Sun, Tao Lin; Nakajima, Tasuku; Kurokawa, Takayuki; Zhao, Yu; Sato, Koshiro; Ihsan, Abu Bin; Li, Xufeng; Guo, Honglei; Gong, Jian Ping

    2015-05-01

    A series of tough polyion complex hydrogels is synthesized by sequential homopolymerization of cationic and anionic monomers. Owing to the reversible interpolymer ionic bonding, the materials are self-healable under ambient conditions with the aid of saline solution. Furthermore, self-glued bulk hydrogels can be built from their microgels, which is promising for 3D/4D printing and the additive manufacturing of hydrogels.

  2. Kinetics of re-equilibrium of oppositely charged hydrogel-surfactant system and its application in controlled release.

    PubMed

    Wang, Wei; Sande, Sv Arne

    2013-06-01

    We report a study of re-equilibrium kinetics of an oppositely charged hydrogel-surfactant system (cationically modified hydroxyethyl cellulose (cat-HEC) and sodium dodecyl sulfate (SDS)) and an application of the formulation for delivery of a water-insoluble molecule. Hydrogels have been applied for long-term delivery of water-soluble drugs due to their controlled-release property. However, the release mechanism of drugs solubilized by surfactants has not been clear. In the present study, SDS was used to solubilize a hydrophobic model drug, and thereafter, by electrostatic interaction between cat-HEC and SDS, the solubilized model drug was loaded into two types of cat-HEC hydrogels with different charge density. We found that the charge density of the polymers had a crucial effect on the loading capacity, without affecting the re-equilibrium kinetics. By an elaborate design of the experiments, the release profiles were fitted with one-dimensional Fickian law where we found the diffusivity of the drug to be constant and comparable to free micelles over a wide region of surfactant concentrations. The observed long-term controlled diffusion is discussed from a thermodynamic point of view.

  3. A method for preparation of hydrogel microcapsules for stem cell bioprocessing and stem cell therapy.

    PubMed

    Goldshmid, Revital; Mironi-Harpaz, Iris; Shachaf, Yonatan; Seliktar, Dror

    2015-08-01

    A method for the preparation of suspension culture microcapsules used in the bioprocessing of human mesenchymal stem cells (hMSCs) is reported. The microcapsules are prepared from a semi-synthetic hydrogel comprising Pluronic®F127 conjugated to denatured fibrinogen. The Pluronic-fibrinogen adducts display a lower critical solubility temperature (LCST) at ∼30 °C, thus enabling mild, cell-compatible physical crosslinking of the microcapsules in a warm gelation bath. Cell-laden microgels were prepared from a solution of Pluronic-fibrinogen hydrogel precursor and hMSCs; these were cultivated for up to 15 days in laboratory-scale suspension bioreactors and harvested by reducing the temperature of the microcapsules to disassemble the physical polymer network. The viability, proliferation and cell recovery yields of the hMSCs were shown to be better than photo-chemically crosslinked microcapsules made from a similar material. The cell culture yields, which exceeded 300% after 15 days in suspension culture, were comparable to other microcarrier systems used for the mass production of hMSCs. The simplicity of this methodology, both in terms of the cell inoculation and mild recovery conditions, represent distinct advantages for stem cell bioprocessing with suspension culture bioreactors. PMID:25931428

  4. Hydrothermal preparation of fluorinated graphene hydrogel for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    An, Haoran; Li, Yu; Long, Peng; Gao, Yi; Qin, Chengqun; Cao, Chen; Feng, Yiyu; Feng, Wei

    2016-04-01

    Fluorinated graphene hydrogels (FGHs) are synthesized through a one-step hydrothermal process and applied as the binder/additive-free electrode materials for supercapacitors. Along with the reduction of graphene oxide (GO), fluorine atoms incorporate into the graphene framework through the substitution process with the residual phenol, ether or carbonyl groups, forming different fluorine species subsequently. The fluorine content and the Csbnd F bond configuration are easily adjusted by the hydrothermal temperature. X-ray photo electron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectra indicate the mainly existent of semi-ionic Csbnd F bonds in the prepared FGHs. The semi-ionic Csbnd F bonds in FGHs facilitate the ion transport, enhance the electrical conductivity and provide active sites for the faradic reaction. Therefore, the electrochemical performances of FGHs are better than the fluorine-free graphene hydrogel prepared by the same hydrothermal process. FGH prepared at the hydrothermal temperature of 150 °C exhibit the highest specific capacitance (227 F g-1) and the best rate capability. The corresponding symmetric supercapacitor delivers the power density as high as 50.05 kW kg-1 at the current density of 50 A g-1. These results indicate the FGHs are the ideal electrode materials with the great potential in the field of high-power supercapacitors.

  5. Preparation and characterization of a novel pH-sensitive hydrogel obtained from UV light-induced polymerization

    NASA Astrophysics Data System (ADS)

    Tian, R. Q.; Zhao, Y. G.; Cui, Y. Q.; Zhang, X. Y.; Zhang, J.; Liang, X. Y.; Shang, Q.

    2015-05-01

    The main aim of this study was to develop a novel pH-sensitive hydrogel prepared via an UV light-induced polymerization. Single-factor experiments were performed to acquire the optimum formula of final poly(MAA-co-PEGMA) hydrogel. Fourier transform infrared spectroscopy (FTIR) spectra were employed to confirm the successful preparation of the designed copolymers. Inner morphologies of the polymeric hydrogels were observed via an S-4800 scanning electron microscope (SEM). Swelling and reversible swelling-shrinking studies were carried out in different phosphate buffer solution (PBS) with various pH values. Drug-loading tests were performed with bovine serum albumin (BSA) as a model drug. The in vitro release profile was also investigated in PBS with the pH values of 1.2 and 7.4. FTIR spectra confirmed the preparation of the poly(MAA-co-PEGMA) copolymers without any residual monomers. The typical space grid structures were observed from the SEM photographs of hydrogels. The obtained hydrogel showed an excellent pH-sensibility and reversible swelling-shrinking property. The maximum drug-loading (40.9 %) was gained from the BSA concentration of 50.0 mg/mL. During the releasing process, only 5.8 ± 0.9 % of BSA was released at pH 1.2, but 82.1 ± 6.2 % was diffused at pH 7.4. These data suggested that such medicated hydrogel could deliver BSA to alkaline conditions (e.g., intestinal environments) site-specifically, which protected BSA from destroying by gastric acid or pepsase. Therefore, such hydrogel had a significant meaning in theoretical research and practical application.

  6. Adsorption of crude oil from aqueous solution by hydrogel of chitosan based polyacrylamide prepared by radiation induced graft polymerization.

    PubMed

    Sokker, H H; El-Sawy, Naeem M; Hassan, M A; El-Anadouli, Bahgat E

    2011-06-15

    The adsorption of crude oil (initial concentration 0.5-30 g/L) from aqueous solution using hydrogel of chitosan based polyacrylamide (PAM) prepared by radiation induced graft polymerization has been investigated. The prepared hydrogel was characterized by FTIR and SEM micrographs. The experiments were carried out as a function of different initial concentrations of oil residue, acrylamide concentration, contact time and pH to determine the optimum condition for the adsorption of residue oil from aqueous solution and sea water. The results obtained showed that the hydrogel prepared at concentration of 40% acrylamide (AAm) and at a radiation dose of 5 kGy has high removal efficiency of crude oil 2.3g/g at pH 3. Equilibrium studies have been carried out to determine the capacity of the hydrogel for adsorption of crude oil, Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms and isotherms constants. Equilibrium data were found to fit very well with both Freundlich and Langmuir models. Also the adsorption of oil onto the hydrogel behaves as a pseudo-second-order kinetic models rather than the pseudo-first-order kinetic model.

  7. A Biocompatible and Biodegradable Protein Hydrogel with Green and Red Autofluorescence: Preparation, Characterization and In Vivo Biodegradation Tracking and Modeling

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyu; Sun, Xiangcheng; Hargrove, Derek; Chen, Jun; Song, Donghui; Dong, Qiuchen; Lu, Xiuling; Fan, Tai-Hsi; Fu, Youjun; Lei, Yu

    2016-01-01

    Because of its good biocompatibility and biodegradability, albumins such as bovine serum albumin (BSA) and human serum albumin (HSA) have found a wide range of biomedical applications. Herein, we report that glutaraldehyde cross-linked BSA (or HSA) forms a novel fluorescent biological hydrogel, exhibiting new green and red autofluorescence in vitro and in vivo without the use of any additional fluorescent labels. UV-vis spectra studies, in conjunction with the fluorescence spectra studies including emission, excitation and synchronous scans, indicated that three classes of fluorescent compounds are presumably formed during the gelation process. SEM, FTIR and mechanical tests were further employed to investigate the morphology, the specific chemical structures and the mechanical strength of the as-prepared autofluorescent hydrogel, respectively. Its biocompatibility and biodegradability were also demonstrated through extensive in vitro and in vivo studies. More interestingly, the strong red autofluorescence of the as-prepared hydrogel allows for conveniently and non-invasively tracking and modeling its in vivo degradation based on the time-dependent fluorescent images of mice. A mathematical model was proposed and was in good agreement with the experimental results. The developed facile strategy to prepare novel biocompatible and biodegradable autofluorescent protein hydrogels could significantly expand the scope of protein hydrogels in biomedical applications.

  8. A Biocompatible and Biodegradable Protein Hydrogel with Green and Red Autofluorescence: Preparation, Characterization and In Vivo Biodegradation Tracking and Modeling

    PubMed Central

    Ma, Xiaoyu; Sun, Xiangcheng; Hargrove, Derek; Chen, Jun; Song, Donghui; Dong, Qiuchen; Lu, Xiuling; Fan, Tai-Hsi; Fu, Youjun; Lei, Yu

    2016-01-01

    Because of its good biocompatibility and biodegradability, albumins such as bovine serum albumin (BSA) and human serum albumin (HSA) have found a wide range of biomedical applications. Herein, we report that glutaraldehyde cross-linked BSA (or HSA) forms a novel fluorescent biological hydrogel, exhibiting new green and red autofluorescence in vitro and in vivo without the use of any additional fluorescent labels. UV-vis spectra studies, in conjunction with the fluorescence spectra studies including emission, excitation and synchronous scans, indicated that three classes of fluorescent compounds are presumably formed during the gelation process. SEM, FTIR and mechanical tests were further employed to investigate the morphology, the specific chemical structures and the mechanical strength of the as-prepared autofluorescent hydrogel, respectively. Its biocompatibility and biodegradability were also demonstrated through extensive in vitro and in vivo studies. More interestingly, the strong red autofluorescence of the as-prepared hydrogel allows for conveniently and non-invasively tracking and modeling its in vivo degradation based on the time-dependent fluorescent images of mice. A mathematical model was proposed and was in good agreement with the experimental results. The developed facile strategy to prepare novel biocompatible and biodegradable autofluorescent protein hydrogels could significantly expand the scope of protein hydrogels in biomedical applications. PMID:26813916

  9. Smart Magnetically Responsive Hydrogel Nanoparticles Prepared by a Novel Aerosol-Assisted Method for Biomedical and Drug Delivery Applications

    PubMed Central

    El-Sherbiny, Ibrahim M.; Smyth, Hugh D. C.

    2011-01-01

    We have developed a novel spray gelation-based method to synthesize a new series of magnetically responsive hydrogel nanoparticles for biomedical and drug delivery applications. The method is based on the production of hydrogel nanoparticles from sprayed polymeric microdroplets obtained by an air-jet nebulization process that is immediately followed by gelation in a crosslinking fluid. Oligoguluronate (G-blocks) was prepared through the partial acid hydrolysis of sodium alginate. PEG-grafted chitosan was also synthesized and characterized (FTIR, EA, and DSC). Then, magnetically responsive hydrogel nanoparticles based on alginate and alginate/G-blocks were synthesized via aerosolization followed by either ionotropic gelation or both ionotropic and polyelectrolyte complexation using CaCl2 or PEG-g-chitosan/CaCl2 as crosslinking agents, respectively. Particle size and dynamic swelling were determined using dynamic light scattering (DLS) and microscopy. Surface morphology of the nanoparticles was examined using SEM. The distribution of magnetic cores within the hydrogels nanoparticles was also examined using TEM. In addition, the iron and calcium contents of the particles were estimated using EDS. Spherical magnetic hydrogel nanoparticles with average particle size of 811 ± 162 to 941 ± 2 nm were obtained. This study showed that the developed method is promising for the manufacture of hydrogel nanoparticles, and it represents a relatively simple and potential low-cost system. PMID:21808638

  10. A novel smart injectable hydrogel prepared by microbial transglutaminase and human-like collagen: Its characterization and biocompatibility.

    PubMed

    Zhao, Leilei; Li, Xian; Zhao, Jiaqi; Ma, Saijian; Ma, Xiaoxuan; Fan, Daidi; Zhu, Chenhui; Liu, Yannan

    2016-11-01

    Various tissue scaffold materials are increasingly used to repair skin defects by cross-linking because of the ability to fill and implant in any form via operation. However, crosslinker residues cannot be easily removed from scaffold materials prepared by chemical crosslinking methods, limiting their use for skin tissue engineering. Here, microbial transglutaminase (MTGase), a nontoxic crosslinker with high specific activity and reaction rate under mild conditions, was employed crosslinks in human-like collagen (HLC) to yield novel smart MTGase crosslinked with human-like collagen (MTGH) hydrogels, which are sensitive to temperature and/or enzymes. Various ratios of MTGase/HLC were performed, and their physicochemical properties were characterized, including the swelling ratio, the elastic modulus, the morphology and the porosity. The degradation behavior and mechanism of MTGase in concentration-dependent manner involved in formation hydrogels were identifying in vitro. The cell attachment in vitro and biocompatibility in vivo were also investigated. The results demonstrated that the use of different concentrations of MTGase to crosslink HLC produced products with different degradation times and biocompatibilities. The 50U/g MTGase-prepared MTGH hydrogels had a higher density of crosslinks, which made them more resistant to degradation by collagenase I and collagenase II. However, 40U/g MTGase-prepared MTGH hydrogels were more suitable for cell attachment. In addition, compared with the Collagen Implant I® (SUM) used in animal experiments, the 40U/g MTGase-prepared MTGH hydrogels had a lower toxicity and better biocompatibility. Therefore, 40U/g MTGase crosslinked with HLC should be used to prepare MTGH hydrogels for potential application as soft materials for skin tissue engineering. PMID:27524026

  11. Designed biodegradable hydrogel structures prepared by stereolithography using poly(ethylene glycol)/poly(D,L-lactide)-based resins.

    PubMed

    Seck, Tetsu M; Melchels, Ferry P W; Feijen, Jan; Grijpma, Dirk W

    2010-11-20

    Designed three-dimensional biodegradable poly(ethylene glycol)/poly(D,L-lactide) hydrogel structures were prepared for the first time by stereolithography at high resolutions. A photo-polymerisable aqueous resin comprising PDLLA-PEG-PDLLA-based macromer, visible light photo-initiator, dye and inhibitor in DMSO/water was used to build the structures. Porous and non-porous hydrogels with well-defined architectures and good mechanical properties were prepared. Porous hydrogel structures with a gyroid pore network architecture showed narrow pore size distributions, excellent pore interconnectivity and good mechanical properties. The structures showed good cell seeding characteristics, and human mesenchymal stem cells adhered and proliferated well on these materials.

  12. Preparation and properties of EDC/NHS mediated crosslinking poly (gamma-glutamic acid)/epsilon-polylysine hydrogels.

    PubMed

    Hua, Jiachuan; Li, Zheng; Xia, Wen; Yang, Ning; Gong, Jixian; Zhang, Jianfei; Qiao, Changsheng

    2016-04-01

    In this paper, a novel pH-sensitive poly (amino acid) hydrogel based on poly γ-glutamic acid (γ-PGA) and ε-polylysine (ε-PL) was prepared by carbodiimide (EDC) and N-hydroxysuccinimide (NHS) mediated polymerization. The influence of PGA/PL molar ratio and EDC/NHS concentration on the structure and properties was studied. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) proved that hydrogels were crosslinked through amide bond linkage, and the conversion rate of a carboxyl group could reach 96%. Scanning electron microscopy (SEM) results showed a regularly porous structure with 20 μm pore size in average. The gelation time in the crosslink process of PGA/PL hydrogels was within less than 5 min. PGA/PL hydrogels had excellent optical performance that was evaluated by a novel optotype method. Furthermore, PGA/PL hydrogels were found to be pH-sensitive, which could be adjusted to the pH of swelling media intelligently. The terminal pH of swelling medium could be controlled at 5 ± 1 after equilibrium when the initial pH was within 3-11. The swelling kinetics was found to follow a Voigt model in deionized water but a pseudo-second-order model in normal saline and phosphate buffer solution, respectively. The differential swelling degrees were attributed to the swelling theory based on the different ratio of -COOH/-NH2 and pore size in hydrogels. The results of mechanical property indicated that PGA/PL hydrogels were soft and elastic. Moreover, PGA/PL hydrogels exhibited excellent biocompatibility by cell proliferation experiment. PGA/PL hydrogels could be degraded in PBS solution and the degradation rate was decreased with the increase of the molar ratio of PL. Considering the simple preparation process and pH-sensitive property, these PGA/PL hydrogels might have high potential for use in medical and clinical fields.

  13. Strong composite films with layered structures prepared by casting silk fibroin-graphene oxide hydrogels.

    PubMed

    Huang, Liang; Li, Chun; Yuan, Wenjing; Shi, Gaoquan

    2013-05-01

    Composite films of graphene oxide (GO) sheets and silk fibroin (SF) with layered structures have been prepared by facile solution casting of SF-GO hydrogels. The as-prepared composite film containing 15% (by weight, wt%) of SF shows a high tensile strength of 221 ± 16 MPa and a failure strain of 1.8 ± 0.4%, which partially surpass those of natural nacre. Particularly, this composite film also has a high modulus of 17.2 ± 1.9 GPa. The high mechanical properties of this composite film can be attributed to its high content of GO (85 wt%), compact layered structure and the strong hydrogen bonding interaction between SF chains and GO sheets. PMID:23538717

  14. Charge regulation and energy dissipation while compressing and sliding a cross-linked chitosan hydrogel layer.

    PubMed

    Liu, Chao; Thormann, Esben; Tyrode, Eric; Claesson, Per M

    2015-04-01

    Interactions between a silica surface and a surface coated with a grafted cross-linked hydrogel made from chitosan/PAA multilayers are investigated, utilizing colloidal probe atomic force microscopy. Attractive double-layer forces are found to dominate the long-range interaction over a broad range of pH and ionic strength conditions. The deduced potential at the hydrogel/aqueous interface is found to be very low. This situation is maintained in the whole pH-range investigated, even though the degree of protonation of chitosan changes significantly. This demonstrates that pH-variations change the concentration of counterions within the hydrogel to keep the interior close to uncharged, which is similar to what has been observed for polyelectrolyte brushes. Changes in pH and ionic strength affect the adhesion force and the friction force between the silica surface and the hydrogel layer, but not the friction coefficient. This suggests that the main energy dissipation mechanism arises from processes occurring within the hydrogel layer, rather than at the silica/hydrogel interface, and we suggest that it is related to stretching of polymer chains between the cross-linking points. We also find that an increased cross-linking density, from 40% to 100%, in the hydrogel reduces the friction coefficient.

  15. PVA/CM-chitosan/honey hydrogels prepared by using the combined technique of irradiation followed by freeze-thawing

    NASA Astrophysics Data System (ADS)

    Afshari, M. J.; Sheikh, N.; Afarideh, H.

    2015-08-01

    Hydrogels with three components, poly(vinyl alcohol) (PVA), carboxymethylate chitosan (CM-chitosan) and honey have been prepared by using radiation method and radiation followed by freeze-thawing cycles technique (combinational method). The solid concentration of the polymer solution is 15 wt% and the ratios of PVA/CM-chitosan/honey are 10/1.5/3.5, 10/2/3, 10/3/2, and 10/3.5/1.5. The applied irradiation doses are 25, 30 and 40 kGy. Various tests have been done to evaluate the hydrogel properties to produce materials to be used as wound dressing. The results show that combinational method improves the mechanical strength of hydrogels while it has no significant effect on the water evaporation rate of gels. The combinational method decreases the swelling of hydrogels significantly, albeit this parameter is still acceptable for wound dressing. Microbiological analyses show that the hydrogel prepared by both methods can protect the wound from Escherichia coli bacterial infection. The wound healing test shows the good performance of the gels in mice.

  16. Strong composite films with layered structures prepared by casting silk fibroin-graphene oxide hydrogels

    NASA Astrophysics Data System (ADS)

    Huang, Liang; Li, Chun; Yuan, Wenjing; Shi, Gaoquan

    2013-04-01

    Composite films of graphene oxide (GO) sheets and silk fibroin (SF) with layered structures have been prepared by facile solution casting of SF-GO hydrogels. The as-prepared composite film containing 15% (by weight, wt%) of SF shows a high tensile strength of 221 +/- 16 MPa and a failure strain of 1.8 +/- 0.4%, which partially surpass those of natural nacre. Particularly, this composite film also has a high modulus of 17.2 +/- 1.9 GPa. The high mechanical properties of this composite film can be attributed to its high content of GO (85 wt%), compact layered structure and the strong hydrogen bonding interaction between SF chains and GO sheets.Composite films of graphene oxide (GO) sheets and silk fibroin (SF) with layered structures have been prepared by facile solution casting of SF-GO hydrogels. The as-prepared composite film containing 15% (by weight, wt%) of SF shows a high tensile strength of 221 +/- 16 MPa and a failure strain of 1.8 +/- 0.4%, which partially surpass those of natural nacre. Particularly, this composite film also has a high modulus of 17.2 +/- 1.9 GPa. The high mechanical properties of this composite film can be attributed to its high content of GO (85 wt%), compact layered structure and the strong hydrogen bonding interaction between SF chains and GO sheets. Electronic supplementary information (ESI) available: XPS spectrum of the SF-GO hybrid film, SEM images of lyophilized GO dispersion and the failure surface of GO film. See DOI: 10.1039/c3nr00196b

  17. Swelling equilibria for temperature-sensitive ampholytic hydrogels

    SciTech Connect

    Baker, J.P.; Stephens, D.R.; Blanch, H.W.; Prausnitz, J.M.

    1992-09-01

    Temperature-sensitive N-isopropylacrylamide (NIPA)-based ampho-lytic hydrogels were synthesized by copolymerizing NIPA with the cationic monomer methacrylamidopropyl trimethylammonium chloride (MAPTAC) and the anionic monomer sodium styrene sulfonate (SSS). The total nominal charge density of the hydrogels was held constant at 8 mol % (dry basis), while the molar ratio of anionic to cationic moieties within the hydrogels was varied. Swelling equilibria were measured in water at 6C, and in aqueous sodium chloride solutions ranging in concentration from 10{sup {minus}5}to 5 M and temperature ranging from 6 to 56C. Consistent with expectations, the swelling behavior of the hydrogels was found to be controlled by temperature at low salt concentrations; as the sodium chloride concentration increased, temperature control of hydrogel swelling decreased. Slight antipolyelectrolyte behavior was observed for the hydrogel prepared with equal molar amounts of MAPTAC and SSS.

  18. Preparation, properties and biological application of pH-sensitive poly(ethylene oxide) (PEO) hydrogels grafted with acrylic acid(AAc) using gamma-ray irradiation

    NASA Astrophysics Data System (ADS)

    Nho, Young Chang; Mook Lim, Youn; Moo Lee, Young

    2004-09-01

    pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by γ-ray irradiation, and then grafting by AAc monomer onto the PEO hydrogels with the subsequent irradiation (radiation dose: 5-20 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. The in vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UV/VIS spectrophotometer. Insulin was loaded into freeze-dried hydrogels (7 mm×3 mm×2.5 mm) and administrated orally to healthy and diabetic Wistar rats. The oral administration of insulin-loaded hydrogels to Wistar rats decreased the blood glucose levels obviously for at least 4 h due to the absorption of insulin in the gastrointestinal tract.

  19. Preparation and characterization of a novel IPN hydrogel memberane of poly( N-isopropylacrylamide)/carboxymethyl chitosan (PNIPAAM/CMCS)

    NASA Astrophysics Data System (ADS)

    Chen, Jie; Sun, Jie; Yang, Liming; Zhang, Qunfei; Zhu, Huina; Wu, Huifeng; Hoffman, Allan S.; Kaetsu, Isao

    2007-08-01

    A novel type of interpenetrating polymer networks (IPN) hydrogel membrane of poly( N-isopropylacrylamide)/carboxymethyl chitosan (PNIPAAm)/(CMCS) was prepared, and the effects of the feed ratio of components, swelling medium and irradiation dose on the swelling and deswelling properties of the hydrogel was systematically studied. The results showed that the introduction of CMCS did not shift the LCST (at 32 °C), which is similar to the pure PNIPAAm. The lowest swelling ratio was at pH 2. There was little influence of irradiation dose on the thermo- and pH-sensitivity of the IPN hydrogel, increasing dose only decreased the swelling ratio. The PNIPAAm:CMCS=1:4 w/w hydrogel was not thermo-sensitive in distilled water, whereas it showed a discontinuous volume phase transition in pH 2 and a continuous one in pH 8 buffer. Consequently, a combination of pH and temperature can be coupled to control the responsive behavior of these hydrogels.

  20. Swelling properties of cassava starch grafted with poly (potassium acrylate-co-acrylamide) superabsorbent hydrogel prepared by ionizing radiation

    SciTech Connect

    Barleany, Dhena Ria Ulfiyani, Fida; Istiqomah, Shafina; Rahmayetty; Heriyanto, Heri; Erizal

    2015-12-29

    Natural and synthetic hydrophylic polymers can be phisically or chemically cross-linked in order to produce hydrogels. Starch based hydrogels grafted with copolymers from acrylic acid or acrylamide have become very popular for water absorbent application. Superabsorbent hydrogels made from Cassava starch grafted with poly (potassium acrylate-co-acrylamide) were prepared by using of ϒ-irradiation method. Various important parameters such as irradiation doses, monomer to Cassava starch ratio and acrylamide content were investigated. The addition of 7,5 % w w{sup −1} acrylamide into the reaction mixture generated a starch graft copolymer with a water absorption in distilled water as high as 460 g g{sup −1} of its dried weight. The effectivity of hydrogel as superabsorbent for aqueous solutions of NaCl and urea was evaluated. The obtained hydrogel showed the maximum absorptions of 317 g g{sup −1} and 523 g g{sup −1} for NaCl and urea solution, respectively (relative to its own dry weight). The structure of the graft copolymer was analyzed by using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM)

  1. Swelling properties of cassava starch grafted with poly (potassium acrylate-co-acrylamide) superabsorbent hydrogel prepared by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Barleany, Dhena Ria; Ulfiyani, Fida; Istiqomah, Shafina; Heriyanto, Heri; Rahmayetty, Erizal

    2015-12-01

    Natural and synthetic hydrophylic polymers can be phisically or chemically cross-linked in order to produce hydrogels. Starch based hydrogels grafted with copolymers from acrylic acid or acrylamide have become very popular for water absorbent application. Superabsorbent hydrogels made from Cassava starch grafted with poly (potassium acrylate-co-acrylamide) were prepared by using of ϒ-irradiation method. Various important parameters such as irradiation doses, monomer to Cassava starch ratio and acrylamide content were investigated. The addition of 7,5 % w w-1 acrylamide into the reaction mixture generated a starch graft copolymer with a water absorption in distilled water as high as 460 g g-1 of its dried weight. The effectivity of hydrogel as superabsorbent for aqueous solutions of NaCl and urea was evaluated. The obtained hydrogel showed the maximum absorptions of 317 g g-1 and 523 g g-1 for NaCl and urea solution, respectively (relative to its own dry weight). The structure of the graft copolymer was analyzed by using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM).

  2. Preparation of hyaluronic acid micro-hydrogel by biotin-avidin-specific bonding for doxorubicin-targeted delivery.

    PubMed

    Cui, Yuan; Li, Yanhui; Duan, Qian; Kakuchi, Toyoji

    2013-01-01

    Hyaluronic acid is a naturally ionic polysaccharide with cancer cell selectivity. It is an ideal candidate material for delivery of anticancer agents. In this study, hyaluronic acid (HA) micro-hydrogel loaded with anticancer drugs was prepared by the biotin-avidin system approach. Firstly, carboxyl groups on HA were changed into amino groups with adipic acid dihydrazide (ADH) to graft with biotin by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride named as HA-biotin. When HA-biotin solution mixed with doxorubicin hydrochloride (DOX·HCl) was blended with neutravidin, the micro-hydrogels would be formed with DOX loading. If excess biotin was added into the microgel, it would be disjointed, and DOX will be released quickly. The results of the synthesis procedure were characterized by (1)H-NMR and FTIR; ADH and biotin have been demonstrated to graft on the HA molecule. A field emission scanning electron microscope was used to observe morphologies of HA micro-hydrogels. Furthermore, the in vitro DOX release results revealed that the release behaviors can be adjusted by adding biotin. Therefore, the HA micro-hydrogel can deliver anticancer drugs efficiently, and the rate of release can be controlled by biotin-specific bonding with the neutravidin. Consequently, the micro-hydrogel will perform the promising property of switching in the specific site in cancer therapy. PMID:23179277

  3. Preparation of morphology-controllable polyaniline and polyaniline/graphene hydrogels for high performance binder-free supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Luo, Jinwei; Zhong, Wenbin; Zou, Yubo; Xiong, Changlun; Yang, Wantai

    2016-07-01

    Polyaniline (PANI) and its composite hydrogels have been considered as a unique supercapacitor electrode material due to their three dimensional (3D) porous structures, formed conducting networks, high specific surface areas and fast electron/ion transfer. Herein, dendritic and long fibrous PANI nanostructure hydrogels (PDH and PFH), dendritic PNAI nanofiber/graphene and long PANI nanofibers/Nitrogen-doped graphene composite hydrogels (PGH and PNGH) were prepared by integration polymerization of aniline and hydrothermal process. It was found that the addition of p-Phenylenediamine (PPD) not only controlled the morphologies of PANI from dendritic to long fibrous, but also facilitated the graphene oxide (GO) into nitrogen-doped graphene. Furthermore, after freeze-drying, PDH and PGH exhibited a max compressive strength of 9.5 and 9.6 KPa, respectively; while the max compressive strength of PFH and PNGH constructed with long PANI nanofiber is 79.9 and 75.8 KPa, respectively. Directly using these prepared hydrogels as electrodes for supercapacitors, it was found that PDH, PFH, PGH and PNGH exhibited high specific capacitances of 448.6, 470, 540.9 and 610 F g-1, respectively, at the current density of 1 A g-1. It is expected that the prepared PDH, PFH, PGH and PNGH can be directly applied in the field of high performance energy storage devices.

  4. Preparation and characterization of smart magnetic hydrogels and its use for drug release

    NASA Astrophysics Data System (ADS)

    Liu, Ting-Yu; Hu, Shang-Hsiu; Liu, Kun-Ho; Liu, Dean-Mo; Chen, San-Yuan

    2006-09-01

    The magnetic hydrogels were successfully fabricated by chemically cross-linking of gelatin hydrogels and Fe 3O 4 nanoparticles (ca. 40-60 nm) through genipin (GP) as cross-linking agent. The cross-sectional SEM observation demonstrates that the Fe 3O 4 nanoparticles were fairly uniformly distributed in the gelatin matrix. Moreover, in vitro release data reveal that drug release profile of the resulting hydrogels is controllable by switching on or off mode of a given magnetic field. While applying magnetic fields to the magnetic hydrogels, the release rate of vitamin B 12 of the hydrogels was considerably decreased as compared with those when the field was turned off, suggesting a close configuration of the hydrogels as a result of the aggregation of Fe 3O 4 nanoparticles. Based on this on-&-off mechanism, the smart magnetic hydrogels based on the gelatin-ferrite hybrid composites can be potentially developed for application in novel drug delivery systems.

  5. Preparation of hydrogel hollow particles for cell encapsulation by a method of polyester core degradation.

    PubMed

    Rabanel, J-M; Hildgen, P

    2004-06-01

    Implantation of encapsulated cells in particles of less than 1 mm (micro-encapsulation) has been proposed as a cell synthesized bio-molecule delivery system. Encapsulation provides immuno-isolation, protecting foreign cells from host immune system while nutrients, oxygen and therapeutic products can diffuse freely across capsule walls. A new method is described for the synthesis of a new family of hollow microparticles for cell encapsulation. Unlike other micro-encapsulation methods, encapsulation in those devices will take place after capsule synthesis, by micro-injection. The microcapsules were prepared by a three-steps original procedure: first, synthesis of a core particle, followed by coating with a layer of epichlorohydrin cross-linked amylo-pectin gel and, finally, selective degradation of the core particle to create the cavity. Initial experiments make use of amylo-pectin cross-linked with trimetaphosphate as core particle material. However, selective degradation was difficult to achieve. In further essays, polyesters were used successfully for the preparation of core particles. Optimizations were carried out and the permeability and morphology of the hollow particles were investigated. The preliminary results show that the new method has the potential to become a standard procedure to obtain hydrogel hollow particles. Moreover, the permeability study seems to be in accordance with specifications for immuno-isolation.

  6. Gelatin-Pectin Composite Films from Polyion Complex Hydrogels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composite films from gelatin and low-methoxyl pectin were prepared by either ionic complexation or covalent cross-linking. The ionic interactions between positively charged gelatin and negatively charged pectin produced physically reversible hydrogels. The resultant homogeneous gels had improved mec...

  7. Preparation and characterization of novel P(HEA/IA) hydrogels for Cd2+ ion removal from aqueous solution

    NASA Astrophysics Data System (ADS)

    Antić, Katarina M.; Babić, Marija M.; Vuković, Jovana J. Jovašević; Vasiljević-Radović, Dana G.; Onjia, Antonije E.; Filipović, Jovanka M.; Tomić, Simonida Lj.

    2015-05-01

    Series of novel hydrogels based on 2-hydroxyethyl acrylate (HEA) and itaconic acid (IA), P(HEA/IA) copolymers, were prepared by free radical cross-linking copolymerization and investigated as potential adsorbents for Cd2+ removal from aqueous solution. The hydrogels before and after Cd2+ adsorption were characterized using FTIR, DSC, SEM/EDX, AFM and DMA analysis. The swelling results showed that these hydrogels are pH and temperature sensitive. In order to evaluate adsorption behavior of samples various factors affecting the Cd2+ uptake behavior, such as: contact time, temperature, pH, ionic strength, adsorbent weight, competitive ions and initial concentration of the metal ions were investigated. Five adsorption isotherms and two kinetic models were studied. The adsorption behavior can be very well described by the pseudo-second order kinetic model and Langmuir isotherm. Multicomponent adsorption studies revealed that adsorption of cadmium depends on the type of metal ions present in the system. Desorption studies showed that hydrogel can be reused three times with only 15% loss of adsorption capacity. All results indicate that the sample with the highest IA content is the most promising adsorbent for Cd2+ removal.

  8. Magnetic/pH-sensitive κ-carrageenan/sodium alginate hydrogel nanocomposite beads: preparation, swelling behavior, and drug delivery.

    PubMed

    Mahdavinia, Gholam Reza; Rahmani, Zeinab; Karami, Shiva; Pourjavadi, Ali

    2014-01-01

    This work describes the preparation of magnetic and pH-sensitive beads based on κ-carrageenan and sodium alginate for use as drug-targeting carriers. Physical cross-linking using K(+)/Ca(2+) ions was applied to obtain ionic cross-linked magnetic hydrogel beads. The produced magnetite beads were thoroughly characterized by TEM, SEM/EDS, XRD, FTIR, and VSM techniques. While the water absorbency (WA) of magnetic beads was enhanced by increasing the weight ratio of κ-carrageenan, introducing magnetic nanoparticles caused a decrease in WA capacity from 15.4 to 6.3 g/g. Investigation on the swelling of the hydrogel beads in NaCl, KCl, and CaCl2 solutions revealed the disintegration of beads depending on the composition of hydrogel beads and the type of metal cations in swelling media. The swelling ratio of beads indicated pH-dependent properties with maximum water absorbing at pH 7.4. Also, it was found that the strength of pH-sensitivity of magnetic beads was low for beads with the high content of carrageenan component. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological-simulated pH values and external magnetic fields. The maximum cumulative releases obtained were 98 and 43% at pH values 7.4 and 1.2, respectively. The Introducing magnetite nanoparticles influenced the cumulative release of drug. PMID:25197770

  9. Silicone hydrogels grafted with natural amino acids for ophthalmological application.

    PubMed

    Xu, Chen; He, Ruiyu; Xie, Binbin; Ismail, Muhammad; Yao, Chen; Luan, Jie; Li, Xinsong

    2016-09-01

    In this report, protein repelling silicone hydrogels with improved hydrophilicity were prepared by photo-polymerization of silicone-containing monomer and glycidyl methacrylate followed by grafting zwitterionic amino acids. The grafted silicone hydrogels possessed excellent hydrophilic surfaces due to the enrichment of amino acids, which was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, contact angle, and equilibrium water content measurements. Remarkable resistance to bovine serum albumin and lysozyme fouling was observed for the silicone hydrogels immobilized with neutrally charged amino acids because of the formation of zwitterionic surfaces with pairs of protonated secondary ammonium cations and deprotonated carboxyl anions. Meanwhile, the silicone hydrogels grafted with positively or negatively charged amino acids were able to repulse same charged protein with reduced deposition and attract oppositely charged protein with increased adsorption. Preliminary cytotoxicity test indicated that the zwitterionic silicone hydrogels were non-cytotoxic. Similarly, three types of natural amino acids, including serine, aspartic acid and histidine, modified silicone hydrogel contact lenses exhibited excellent hydrophilicity and non-damage to the rabbit's eyes, but only serine modified zwitterionic contact lens showed superior protein fouling resistance compared with the current commercial hydrogel contact lens, which may have great potential application in ophthalmology.

  10. Rheological properties of a biological thermo-responsive hydrogel prepared from vegetable oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrogel is a colloidal gel in which water is the dispersion medium. The unique properties of hydrogels make this kind of materials have many utilization potentials, such as drug delivery, gene therapy, wound care products, breast implant materials, cosmetic products, and tissue engineering. Hydroge...

  11. Preparation and characterization of gatifloxacin-loaded sodium alginate hydrogel membranes supplemented with hydroxypropyl methylcellulose and hydroxypropyl cellulose polymers for wound dressing

    PubMed Central

    Prabu, Durai; Majdalawieh, Amin F.; Abu-Yousef, Imad A.; Inbasekaran, Kadambari; Balasubramaniam, Tharani; Nallaperumal, Narayanan; Gunasekar, Conjeevaram J.

    2016-01-01

    Introduction: The aim of this study is to evaluate gatifloxacin-loaded sodium alginate hydrogel membranes, supplemented with glycerol (a plasticizer), glutaraldehyde (a cross-linking agent), and hydroxypropyl methylcellulose (HPMC) or hydroxypropyl cellulose (HPC) polymers, as potential wound dressing materials based on their physicochemical properties and the sustain-release phenomenon. Materials and Methods: The physicochemical properties of the prepared hydrogel membranes were evaluated by several methods including Fourier transform infrared and differential scanning calorimetry. Different techniques were used to assess the swelling behavior, tensile strength and elongation, % moisture absorption, % moisture loss, water vapor transmission rate (WVTR), and microbial penetration for the hydrogel membranes. In vitro gatifloxacin release from the hydrogel membranes was examined using the United States Pharmacopeia XXIII dissolution apparatus. Four kinetics models (zero-order, first-order, Higuchi equation, and Korsmeyer-Peppas equation) were applied to study drug release kinetics. Results: The addition of glycerol, glutaraldehyde, HPMC, and HPC polymers resulted in a considerable increase in the tensile strength and flexibility/elasticity of the hydrogel membranes. WVTR results suggest that hydrated hydrogel membranes can facilitate water vapor transfer. None of the hydrogel membranes supported microbial growth. HPMC-treated and HPC-treated hydrogel membranes allow slow, but sustained, release of gatifloxacin for 48 h. Drug release kinetics revealed that both diffusion and dissolution play an important role in gatifloxacin release. Conclusions: Given their physicochemical properties and gatifloxacin release pattern, HPMC-treated and HPC-treated hydrogel membranes exhibit effective and sustained drug release. Furthermore, HPMC-treated and HPC-treated hydrogel membranes possess physiochemical properties that make them effective and safe wound dressing materials. PMID

  12. Biomimetic Hydrogel Materials

    DOEpatents

    Bertozzi, Carolyn , Mukkamala, Ravindranath , Chen, Oing , Hu, Hopin , Baude, Dominique

    2003-04-22

    Novel biomimetic hydrogel materials and methods for their preparation. Hydrogels containing acrylamide-functionalized carbohydrate, sulfoxide, sulfide or sulfone copolymerized with a hydrophilic or hydrophobic copolymerizing material selected from the group consisting of an acrylamide, methacrylamide, acrylate, methacrylate, vinyl and a derivative thereof present in concentration from about 1 to about 99 wt %. and methods for their preparation. The method of use of the new hydrogels for fabrication of soft contact lenses and biomedical implants.

  13. Biomimetic hydrogel materials

    DOEpatents

    Bertozzi, Carolyn; Mukkamala, Ravindranath; Chen, Qing; Hu, Hopin; Baude, Dominique

    2000-01-01

    Novel biomimetic hydrogel materials and methods for their preparation. Hydrogels containing acrylamide-functionalized carbohydrate, sulfoxide, sulfide or sulfone copolymerized with a hydrophilic or hydrophobic copolymerizing material selected from the group consisting of an acrylamide, methacrylamide, acrylate, methacrylate, vinyl and a derivative thereof present in concentration from about 1 to about 99 wt %. and methods for their preparation. The method of use of the new hydrogels for fabrication of soft contact lenses and biomedical implants.

  14. Novel Hydrogels from Renewable Resources

    NASA Astrophysics Data System (ADS)

    Karaaslan, Muzafer Ahmet

    2011-12-01

    The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In the first part of this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose and glucose. The effect of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study and ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid. The aim of the second part of this study was to control the crosslink density and the mechanical properties of hemicellulose/chitosan semi-IPN hydrogels by changing the crosslinking sequence. It has been hypothesized that by performing the crosslinking step before introducing hemicellulose, covalent crosslinking of chitosan would not be hindered and therefore more and/or shorter crosslinks could be formed. Furthermore, additional secondary interactions and crystalline domains introduced through hemicellulose could be favorable in terms of

  15. Porous Agarose-Based Semi-IPN Hydrogels: Characterization and Cell Affinity Studies.

    PubMed

    Vardar, E; Vert, Michel; Coudane, Jean; Hasirci, V; Hasirci, N

    2012-01-01

    Hydrogels are frequently considered for medical applications due to the ease of preparation in different forms and high water content that makes them comparable to natural tissues. However, these general properties are not sufficient to make any hydrogel suitable for cell attachment and growth which are necessary for their use in tissue regeneration. Besides, the high water content makes the hydrogels mechanically weak. The formation of semi-interpenetrating networks (semi-IPNs) can be used in attempts to enhance physical, mechanical and thermal properties. In this study, semi-IPNs of agarose were prepared with chitosan and alginate, two polyelectrolytes that are positively and negatively charged under physiological conditions, respectively. Zeta potential was used to confirm the formation of charged hydrogels. All hydrogels had ultimate compression strengths in the range of 91-210 Pa where the value for pure agarose was about 103 Pa. Chitosan increased the compressive strength about two folds whereas the alginate had opposite effects. The amount of strongly bound water present in the hydrogels were estimated from TGA and DSC analysis and the highest value was found for alginate-agarose hydrogels as about 15%. The attachment and the migration of L929 fibroblasts were monitored in vitro using the MTS assay and confocal microscopy. The highest cell proliferation and penetration were observed for positively charged chitosan-agarose semi-IPN hydrogels.

  16. Self-Adjustable Adhesion of Polyampholyte Hydrogels.

    PubMed

    Roy, Chanchal Kumar; Guo, Hong Lei; Sun, Tao Lin; Ihsan, Abu Bin; Kurokawa, Takayuki; Takahata, Masakazu; Nonoyama, Takayuki; Nakajima, Tasuku; Gong, Jian Ping

    2015-12-01

    Developing nonspecific, fast, and strong adhesives that can glue hydrogels and biotissues substantially promotes the application of hydrogels as biomaterials. Inspired by the ubiquitous adhesiveness of bacteria, it is reported that neutral polyampholyte hydrogels, through their self-adjustable surface, can show rapid, strong, and reversible adhesion to charged hydrogels and biological tissues through the Coulombic interaction.

  17. Thixotropic injectable hydrogel using a polyampholyte and nanosilicate prepared directly after cryopreservation.

    PubMed

    Jain, Minkle; Matsumura, Kazuaki

    2016-12-01

    Success of tissue engineering applications in regenerative medicine requires the preservation of tissue-engineered products at a low temperature. This can be successfully achieved by the use of cryoprotective agent (CPA). In this study, we formulated a unique injectable hydrogel for the purpose of cell delivery after cryopreservation by using polyampholyte CPA. The polyampholyte showed excellent post-thaw cell survival, and after thawing, the polymeric CPA did not have to be removed because of its low cytotoxicity. The polyampholyte could be transformed into a hydrogel by mixing with nanosilicates. Previously, nanosilicates were used to improve mechanical properties, but this is the first report of the use of a nanosilicate together with CPA to formulate hydrogels. Inclusion of the nanosilicate led to the formation of thixotropic hydrogels, which can be injected using fine needles. These gels with tunable mechanical properties can be injected into defect sites to form scaffolds for cell growth and tissue repair, and they do not require any separate seeding of cells before injection, thus eliminating the need for cell harvesting and cell maintenance. This is a distinct system in which cells can be cryopreserved until before usage; when required, the cells in the polyampholyte can be revived to their original state and the thixotropic hydrogel can be formed. The combination of thixotropy and cytocompatibility of the gels could enable a wide range of biomedical applications such as cell delivery and orthopedic repair. PMID:27612827

  18. Novel zinc alginate hydrogels prepared by internal setting method with intrinsic antibacterial activity.

    PubMed

    Straccia, Maria Cristina; d'Ayala, Giovanna Gomez; Romano, Ida; Laurienzo, Paola

    2015-07-10

    In this paper, a controlled gelation of alginate was performed for the first time using ZnCO3 and GDL. Uniform and transparent gels were obtained and investigated as potential wound dressings. Homogeneity, water content, swelling capability, water evaporation rate, stability in normal saline solution, mechanical properties and antibacterial activity were assessed as a function of zinc concentration. Gelation rate increased at increasing zinc content, while a decrease in water uptake and an improvement of stability were found. Release of zinc in physiological environments showed that concentration of zinc released in solution lies below the cytotoxicity level. Hydrogels showed antimicrobial activity against Escherichia coli. The hydrogel with highest zinc content was stabilized with calcium by immersion in a calcium chloride solution. The resulting hydrogel preserved homogeneity and antibacterial activity. Furthermore, it showed even an improvement of stability and mechanical properties, which makes it suitable as long-lasting wound dressing.

  19. Physical properties of gamma irradiated poly(vinyl alcohol) hydrogel preparations

    NASA Astrophysics Data System (ADS)

    Mondino, A. V.; González, M. E.; Romero, G. R.; Smolko, E. E.

    1999-08-01

    Poly(vinyl alcohol) films from 15% w/w aqueous solutions and a thickness of 0.2 mm were selected for this study. The films were first humidified and then acetalized and/or gamma irradiated. Then, their physical properties were tested. Tensile strength of the hydrogel films reached its maximum value in samples irradiated with a 80 kGy dose, in the case of acetalized films the dose necessary for maximum tensile strength was only 40 kGy. The combination of acetalization with formaldehyde and gamma radiation produced an elastic hydrogel with good tackiness and excellent mechanical and thermal strength.

  20. Effects of initial-fixed charge density on pH-sensitive hydrogels subjected to coupled pH and electric field stimuli: a meshless analysis.

    PubMed

    Ng, T Y; Li, Hua; Yew, Y K; Lam, K Y

    2007-04-01

    In this paper, we study the effects of initial fixed-charge density on the response behavior of pH-sensitive hydrogels subjected to coupled stimuli, namely, solution pH and externally applied electric field. This is the first instance in which a coupled stimuli numerical analysis has been carried out for these polymer gels, which are used as active sensing/actuating elements in advanced biomicroelectromechanical systems devices. In this work, a chemo-electro-mechanical formulation, termed the multi-effect-coupling pH-stimulus (MECpH) model, is first presented. This mathematical model takes into account the ionic species diffusion, electric potential coupling, and large mechanical deformation. In addition, a correlation between the diffusive hydrogen ions and fixed-charge groups on the hydrogel polymeric chains is established based on the Langmuir absorption isotherm, and incorporated accordingly into the MECpH model. To solve the resulting highly nonlinear and highly coupled partial differential equations of this mathematical model, the Hermite-Cloud method, a novel true meshless technique, is employed. To demonstrate the accuracy and robustness the MECpH model, computed numerical results are compared with experimental data available from literature. Following this validation, several numerical studies are carried out to investigate the effects of initial fixed-charge density on the volumetric variations of these pH-stimulus-responsive hydrogels when immersed in buffered solutions.

  1. Contemporary issues in hydrogels research

    SciTech Connect

    Peppas, N.A.

    1993-12-31

    The last ten years has seen an explosion in hydrogels research, the result of improved understanding of the structure and behavior of these water-swollen, crosslinked polymers. After the early developments of Flory And Katchalsky in the 1940s, the great Czechoslovakian researchers of the 1960s and Andrade, Hoffman, Ratner and Merrill of the early 1970s, hydrogels have again attracted significant research interest, especially through the imaginative research of Tanaka in the 1980s and others. Eight general areas of contemporary research in hydrogels are identified: (i) kinetic analysis of the copolymerization/crosslinking reactions used in hydrogel preparation; (ii) gelation and percolation theories; (iii) novel methods for tailor-made copolymers with desirable functional groups, or biodegradable chains; (iv) biomimetic hydrogels; (V) hydrogels of controlled porous structure; (vi) ultrapure hydrogels devoid of crosslinking agents, emulsifiers, etc.; (vii) critical phenomena in hydrogels; and (viii) behavior of anionic, cationic and amphiphilic hydrogels.

  2. Cyclodextrin/dextran based hydrogels prepared by cross-linking with sodium trimetaphosphate.

    PubMed

    Wintgens, Véronique; Lorthioir, Cédric; Dubot, Pierre; Sébille, Bernard; Amiel, Catherine

    2015-11-01

    Novel βCD-based hydrogels have been synthesized using sodium trimetaphosphate (STMP) as non-toxic reagent. Straightforward mixing of βCD with dextran and STMP in basic aqueous media led to hydrogels incorporating dextran chains, phosphate groups and βCD units. The hydrogels have been characterized by swelling measurements, XPS and (31)P NMR. The swelling ratio was correlated to the content in phosphated groups, which give a polyelectrolyte character to these hydrogels. The significant rise of the swelling ratio with the βCD content increase has been attributed to a decrease of the number of phosphate-based crosslinks, the βCD units playing the role of dangling ends in the tridimensional network. Their loading capacity and their release properties have been investigated for methylene blue and benzophenone in order to demonstrate their potentiality for drug delivery. Through different interaction mechanisms, electrostatic and inclusion complex interactions, these compounds are loaded with different efficiencies. The release involves deswelling, diffusion mechanisms and partition equilibrium. PMID:26256327

  3. Cyclodextrin/dextran based hydrogels prepared by cross-linking with sodium trimetaphosphate.

    PubMed

    Wintgens, Véronique; Lorthioir, Cédric; Dubot, Pierre; Sébille, Bernard; Amiel, Catherine

    2015-11-01

    Novel βCD-based hydrogels have been synthesized using sodium trimetaphosphate (STMP) as non-toxic reagent. Straightforward mixing of βCD with dextran and STMP in basic aqueous media led to hydrogels incorporating dextran chains, phosphate groups and βCD units. The hydrogels have been characterized by swelling measurements, XPS and (31)P NMR. The swelling ratio was correlated to the content in phosphated groups, which give a polyelectrolyte character to these hydrogels. The significant rise of the swelling ratio with the βCD content increase has been attributed to a decrease of the number of phosphate-based crosslinks, the βCD units playing the role of dangling ends in the tridimensional network. Their loading capacity and their release properties have been investigated for methylene blue and benzophenone in order to demonstrate their potentiality for drug delivery. Through different interaction mechanisms, electrostatic and inclusion complex interactions, these compounds are loaded with different efficiencies. The release involves deswelling, diffusion mechanisms and partition equilibrium.

  4. Preparation of biodegradable xanthan-glycerol hydrogel, foam, film, aerogel and xerogel at room temperature.

    PubMed

    Bilanovic, Dragoljub; Starosvetsky, Jeanna; Armon, Robert H

    2016-09-01

    Polymers, hence hydrogels, pollute waters and soils accelerating environmental degradation. Environmentally benign hydrogels were made in water from biodegradable xanthan (X) and glycerol (G) at 22.5±2.5°C. Molar ratio [G]/[X]<3.0 was used to maximize crosslinking by mono-glycerol instead by poly-glycerol. XG-hydrogels were transformed into: XG-foams, XG-films, and XG-aerogel. Anionic character of XG-materials changes with changing [G]/[X] ratio. XG-films made from XG-hydrogels absorb up to 40 times more water than XG-films made from XG-foams. The films made from XG-foams and HCl do not dissolve in water during 48h. Making XG-materials is a no-waste process which decreases pollution, eliminates waste disposal costs, and minimizes energy expenses. XG-materials are suitable for both industrial and environmental applications including slow release and concentration of cations. XG-materials, made of xanthan, microbial polysaccharide, could also be used in applications targeting populations that do not consume meat or meat based products. PMID:27185137

  5. Preparation of biodegradable xanthan-glycerol hydrogel, foam, film, aerogel and xerogel at room temperature.

    PubMed

    Bilanovic, Dragoljub; Starosvetsky, Jeanna; Armon, Robert H

    2016-09-01

    Polymers, hence hydrogels, pollute waters and soils accelerating environmental degradation. Environmentally benign hydrogels were made in water from biodegradable xanthan (X) and glycerol (G) at 22.5±2.5°C. Molar ratio [G]/[X]<3.0 was used to maximize crosslinking by mono-glycerol instead by poly-glycerol. XG-hydrogels were transformed into: XG-foams, XG-films, and XG-aerogel. Anionic character of XG-materials changes with changing [G]/[X] ratio. XG-films made from XG-hydrogels absorb up to 40 times more water than XG-films made from XG-foams. The films made from XG-foams and HCl do not dissolve in water during 48h. Making XG-materials is a no-waste process which decreases pollution, eliminates waste disposal costs, and minimizes energy expenses. XG-materials are suitable for both industrial and environmental applications including slow release and concentration of cations. XG-materials, made of xanthan, microbial polysaccharide, could also be used in applications targeting populations that do not consume meat or meat based products.

  6. Functionalization, preparation and use of cell-laden gelatin methacryloyl-based hydrogels as modular tissue culture platforms.

    PubMed

    Loessner, Daniela; Meinert, Christoph; Kaemmerer, Elke; Martine, Laure C; Yue, Kan; Levett, Peter A; Klein, Travis J; Melchels, Ferry P W; Khademhosseini, Ali; Hutmacher, Dietmar W

    2016-04-01

    Progress in advancing a system-level understanding of the complexity of human tissue development and regeneration is hampered by a lack of biological model systems that recapitulate key aspects of these processes in a physiological context. Hence, growing demand by cell biologists for organ-specific extracellular mimics has led to the development of a plethora of 3D cell culture assays based on natural and synthetic matrices. We developed a physiological microenvironment of semisynthetic origin, called gelatin methacryloyl (GelMA)-based hydrogels, which combine the biocompatibility of natural matrices with the reproducibility, stability and modularity of synthetic biomaterials. We describe here a step-by-step protocol for the preparation of the GelMA polymer, which takes 1-2 weeks to complete, and which can be used to prepare hydrogel-based 3D cell culture models for cancer and stem cell research, as well as for tissue engineering applications. We also describe quality control and validation procedures, including how to assess the degree of GelMA functionalization and mechanical properties, to ensure reproducibility in experimental and animal studies.

  7. [Study on preparation of the pH sensitive hydroxyethyl chitin/poly (acrylic acid) hydrogel and its drug release property].

    PubMed

    Zhao, Yu; Chen, Guohua; Sun, Mingkun; Jin, Zhitao; Gao, Congjie

    2006-04-01

    Hydroxyethyl chitin (HECH) is a water soluble chitin derivative made by etherification of chitin, ethylene chlorohydrin was used as etherification reagent in this reaction. A novel interpenetrating polymer network (IPN) composed of HECH/PAA was prepared. The IR spectra confirmed that HECH/PAA was formed through chemical bond interaction. The sensitivity of this hydrogel to temperature and pH was studied. The swelling ratio of this hydrogel in artificial intestinal juice is much greater than that in artificial gastric juice. The IPN hydrogel exhibited a typical pH-sensitivity, and its degree of swelling ratio increased with the increase of temperature. The sustained-release drug system of Dichlofenac potassium was prepared by using HECH/PAA as the drug carrier. The release experiment showed a perfect release behavior in artificial intestinal juice. This IPN is expected to be used as a good drug delivery system of enteric medicine. PMID:16706361

  8. Desmosine-Inspired Cross-Linkers for Hyaluronan Hydrogels

    NASA Astrophysics Data System (ADS)

    Hagel, Valentin; Mateescu, Markus; Southan, Alexander; Wegner, Seraphine V.; Nuss, Isabell; Haraszti, Tamás; Kleinhans, Claudia; Schuh, Christian; Spatz, Joachim P.; Kluger, Petra J.; Bach, Monika; Tussetschläger, Stefan; Tovar, Günter E. M.; Laschat, Sabine; Boehm, Heike

    2013-06-01

    We designed bioinspired cross-linkers based on desmosine, the cross-linker in natural elastin, to prepare hydrogels with thiolated hyaluronic acid. These short, rigid cross-linkers are based on pyridinium salts (as in desmosine) and can connect two polymer backbones. Generally, the obtained semi-synthetic hydrogels are form-stable, can withstand repeated stress, have a large linear-elastic range, and show strain stiffening behavior typical for biopolymer networks. In addition, it is possible to introduce a positive charge to the core of the cross-linker without affecting the gelation efficiency, or consequently the network connectivity. However, the mechanical properties strongly depend on the charge of the cross-linker. The properties of the presented hydrogels can thus be tuned in a range important for engineering of soft tissues by controlling the cross-linking density and the charge of the cross-linker.

  9. Polyimide Nanocomposites Prepared from High-Temperature, Reduced Charge Organoclays

    NASA Technical Reports Server (NTRS)

    Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Ladislaw, J. S.; Smith, J. G., Jr.; Connell, J. W.

    2003-01-01

    Montmorillonite clays modified with the dihydrochloride salt of 1,3-bis(3-aminophenoxy)benzene (APB) were used in the preparation of polyimide/organoclay hybrid films. Organoclays with varying surface charge based upon APB were prepared and examined for their dispersion behavior in the polymer matrix. High molecular weight poly(amide acid) solutions were prepared in the presence of the organoclays. Films were cast and subsequently heated to 300C to cause imidization. The resulting nanocomposite films, containing 3 wt% of organoclay, were characterized by transmission electron microscopy and X-ray diffraction. The clay's cation exchange capacity (CEC) played a key role in determining the extent of dispersion in the polyimide matrix. Considerable dispersion was observed in some of the nanocomposite films. The most effective organoclay was found to have a CEC of 0.70 meq/g. Nanocomposite films prepared with 3-8 wt% of this organoclay were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin-film tensile testing. High levels of clay dispersion could be achieved even at the higher clay loadings. Results from mechanical testing revealed that while the moduli of the nanocomposites increased with increasing clay loadings, both strength and elongation decreased.

  10. Enzyme-mediated in situ preparation of biocompatible hydrogel composites from chitosan derivative and biphasic calcium phosphate nanoparticles for bone regeneration

    NASA Astrophysics Data System (ADS)

    Phuong Nguyen, Thi; Hai Phuong Doan, Bach; Dang, Dinh Vu; Khoa Nguyen, Cuu; Quyen Tran, Ngoc

    2014-03-01

    Injectable chitosan-based hydrogels have been widely studied toward biomedical applications because of their potential performance in drug/cell delivery and tissue regeneration. In this study we introduce tetronic-grafted chitosan containing tyramine moieties which have been utilized for in situ enzyme-mediated hydrogel preparation. The hydrogel can be used to load nanoparticles (NPs) of biphasic calcium phosphate (BCP), mixture of hydroxyapatite (HAp) and tricalcium phosphate (TCP), forming injectable biocomposites. The grafted copolymers were well-characterized by 1H NMR. BCP nanoparticles were prepared by precipitation method under ultrasonic irradiation and then characterized by using x-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The suspension of the copolymer and BCP nanoparticles rapidly formed hydrogel biocomposite within a few seconds of the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The compressive stress failure of the wet hydrogel was at 591 ± 20 KPa with the composite 10 wt% BCP loading. In vitro study using mesenchymal stem cells showed that the composites were biocompatible and cells are well-attached on the surfaces.

  11. Injectable hybrid hydrogels of hyaluronic Acid crosslinked by well-defined synthetic polycations: preparation and characterization in vitro and in vivo.

    PubMed

    Cross, Daisy; Jiang, Xiaoze; Ji, Weihang; Han, Wenqing; Wang, Chun

    2015-05-01

    An injectable hybrid hydrogel system was developed consisting of hyaluronic acid (HA) crosslinked by well-defined block copolymers of the cationic poly(2-aminoethyl methacrylate) (PAEM) and polyethylene glycol (PEG). Robust, shear-thinning hybrid hydrogel was produced by mixing HA and 4-arm star PEG-PAEM block copolymer at 1:1 charge ratio. The encapsulation and release of highly viable human mesenchymal stem cells in physiological media was demonstrated. After subcutaneous injection of the hybrid gel in mice, mild but resolvable inflammatory response was observed. This hybrid gel could serve as a model system for studying structure-function relationship of polyelectrolyte hydrogels and as a practical injectable biomaterial for medical applications.

  12. Preparation of monodisperse PEG hydrogel composite microspheres via microfluidic chip with rounded channels

    NASA Astrophysics Data System (ADS)

    Yu, Bing; Cong, Hailin; Liu, Xuesong; Ren, Yumin; Wang, Jilei; Zhang, Lixin; Tang, Jianguo; Ma, Yurong; Akasaka, Takeshi

    2013-09-01

    An effective microfluidic method to fabricate monodisperse polyethylene glycol (PEG) hydrogel composite microspheres with tunable dimensions and properties is reported in this paper. A T-junction microfluidic chip equipped with rounded channels and online photopolymerization system is applied for the microsphere microfabrication. The shape and size of the microspheres are well controlled by the rounded channels and PEG prepolymer/silicon oil flow rate ratios. The obtained PEG/aspirin composite microspheres exhibit a sustained release of aspirin for a wide time range; the obtained PEG/Fe3O4 nanocomposite microspheres exhibit excellent magnetic properties; and the obtained binary PEG/dye composite microspheres show the ability to synchronously load two functional components in the same peanut-shaped or Janus hydrogel particles.

  13. Preparation of hydrogel by radiation for the healing of diabetic ulcer

    NASA Astrophysics Data System (ADS)

    Nho, Young-Chang; Park, Jong-Seok; Lim, Youn-Mook

    2014-01-01

    Honey has been used in wound care for thousands of years. The major advantage of honey in wound care is the high osmotic activity, which accelerates the debridement of necrotic tissue and procures an antibacterial effect. It has been reported that the ancient Greeks and Romans used honey as a topical antiseptic for sores and skin ulcers. The aims of this study were to evaluate the antibacterial activities and the healing effect for diabetic ulcers from carboxymethyl cellulose (CMC) hydrogel involving honey.

  14. Preparation and characterization of in-situ crosslinked pectin-gelatin hydrogels.

    PubMed

    Gupta, Bhuvanesh; Tummalapalli, Mythili; Deopura, B L; Alam, M S

    2014-06-15

    Crosslinked hydrogels were developed by in-situ reaction of periodate oxidized pectin (OP) and gelatin. The reaction takes place through the formation of Schiff bases between aldehyde groups of OP and amino groups of gelatin. The effect of various process parameters such as reaction time, reaction temperature, pH of the reaction and composition on the efficacy of the crosslinking was investigated. Field emission scanning electron micrsocopy (FESEM) revealed that homogenous, single phase systems are obtained after the crosslinking of OP and gelatin. The swelling characteristics of the hydrogels were monitored. The equilibrium swelling varies in the range of 195-324% with a variation in the gelatin content (10-40%). Glycerol, when used as a plasticizer, improved the flexibility and the handling characteristics of the crosslinked hydrogels. Plasticized films retained good tensile strengths in the range of 19-48 MPa. By proper selection of the reaction conditions, the efficiency of crosslinking can be controlled to obtain the optimum results.

  15. Preparation and theophylline delivery applications of novel PMAA/MWCNT-COOH nanohybrid hydrogels.

    PubMed

    Zhang, Chang-Hu; Luo, Yan-Ling; Chen, Ya-Shao; Wei, Qing-Bo; Fan, Li-Hua

    2009-01-01

    A series of nanohybrid hydrogels was designed and developed based on a hydrogen bond self-assembly of poly(methacrylic acid) (PMAA) networks and carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH). The nanohybrid hydrogels show low micropore densities and large mesh sizes with an increase in MWCNT-COOH content. Particularly, the hydrogels containing 10 wt% MWCNT-COOH was observed to collapse at pore walls because of large holes, which is believed to be responsible for high swelling. The ability of the MWCNT-COOH to self-associate with PMAA or water molecules via hydrogen-bonding interactions and an additional electrostatic repulsion govern both pH response of the network and drug release. Increasing pH values causes equilibrium swelling ratios and accumulative release to be elevated. On the other hand, modified mechanical behavior can be obtained under a low content of the MWCNT-COOH in that the high MWCNT-COOH filling effects the formation of PMAA gel networks. Swelling and controlled release profiles of theophylline could be modulated by changing pH values, introducing the MWCNT-COOH and adjusting the proportions of the MWCNT-COOH component.

  16. Facile preparation of mussel-inspired polyurethane hydrogel and its rapid curing behavior.

    PubMed

    Sun, Peiyu; Wang, Jing; Yao, Xiong; Peng, Ying; Tu, Xiaoxiong; Du, Pengfei; Zheng, Zhen; Wang, Xinling

    2014-08-13

    A facile method was found to incorporate a mussel-inspired adhesive moiety into synthetic polymers, and mussel mimetic polyurethanes were developed as adhesive hydrogels. In these polymers, a urethane backbone was substituted for the polyamide chain of mussel adhesive proteins, and dopamine was appended to mimic the adhesive moiety of adhesive proteins. A series of mussel mimetic polyurethanes were created through a step-growth polymerization based on hexamethylene diisocyanate as a hard segment, PEG having different molecular weights as a soft segment, and lysine-dopamine as a chain extender. Upon a treatment with Fe(3+), the aqueous mussel mimetic polyurethane solutions can be triggered by pH adjustment to form adhesive hydrogels instantaneously; these materials can be used as injectable adhesive hydrogels. Upon a treatment with NaIO4, the mussel mimetic polyurethane solutions can be cured in a controllable period of time. The successful combination of the unique mussel-inspired adhesive moiety with a tunable polyurethane structure can result in a new kind of mussel-inspired adhesive polymers.

  17. A cotton fabric modified with a hydrogel containing ZnO nanoparticles. Preparation and properties study

    NASA Astrophysics Data System (ADS)

    Staneva, Desislava; Atanasova, Daniela; Vasileva-Tonkova, Evgenia; Lukanova, Varbina; Grabchev, Ivo

    2015-08-01

    Two different methods were used to obtain composite materials based on a ZnO nanoparticles-hydrogel-cotton fabric. The hydrogels, synthesized by photopolymerization, were utilized to provide uniform distribution and binding of the nanoparticles to the fiber surface and to prevent their agglomeration. N-methyldiethanolamine (MDEA) was used as a co-initiator in hydrogel photopolymerization and as an alkaline agent in the synthesis of ZnO nanoparticles. Due to the difference in size, shape and morphology of the nanoparticles, examined by a TEM and SEM, it was found that the materials have distinct photoluminescence properties, e.g. in the entire visible or UV range. The composite materials with small size nanoparticles and photoluminescence in near UV range were investigated for antibiotic activity against the bacterial strains Pseudomonas aeruginosa and Acinetobacter johnsonii known as important pathogens in clinical infections. Significantly high antibacterial effect on the bacteria tested was achieved, especially on A. johnsonii. This suggests potential application of the new formulations as effective wound dressings to control the spread of infections.

  18. Cationic cellulose hydrogels cross-linked by poly(ethylene glycol): Preparation, molecular dynamics, and adsorption of anionic dyes.

    PubMed

    Kono, Hiroyuki; Ogasawara, Kota; Kusumoto, Ryo; Oshima, Kazuhiro; Hashimoto, Hisaho; Shimizu, Yuuichi

    2016-11-01

    Cationic cellulose hydrogels (CCGs) were prepared from quaternized celluloses with degrees of substitution (DS) of 0.56, 0.84, and 1.33, by the cross-linking reaction with poly(ethylene glycol) diglycidyl ether as a cross-linker. The CCGs exhibited swelling behavior in aqueous solutions, which was not affected by pH and temperature of the solution because of the presence of quaternary ammonium groups in their structures. The CCGs showed adsorption ability toward anionic dyes in aqueous solution, which increased with increasing DS. The dye adsorption was found to follow the pseudo-second order kinetic model and the equilibrium isotherm data can be described by the Langmuir adsorption model. In addition, the CCGs could be regenerated and proved to be recyclable adsorbents for wastewater treatment. PMID:27516262

  19. Cationic cellulose hydrogels cross-linked by poly(ethylene glycol): Preparation, molecular dynamics, and adsorption of anionic dyes.

    PubMed

    Kono, Hiroyuki; Ogasawara, Kota; Kusumoto, Ryo; Oshima, Kazuhiro; Hashimoto, Hisaho; Shimizu, Yuuichi

    2016-11-01

    Cationic cellulose hydrogels (CCGs) were prepared from quaternized celluloses with degrees of substitution (DS) of 0.56, 0.84, and 1.33, by the cross-linking reaction with poly(ethylene glycol) diglycidyl ether as a cross-linker. The CCGs exhibited swelling behavior in aqueous solutions, which was not affected by pH and temperature of the solution because of the presence of quaternary ammonium groups in their structures. The CCGs showed adsorption ability toward anionic dyes in aqueous solution, which increased with increasing DS. The dye adsorption was found to follow the pseudo-second order kinetic model and the equilibrium isotherm data can be described by the Langmuir adsorption model. In addition, the CCGs could be regenerated and proved to be recyclable adsorbents for wastewater treatment.

  20. Ionic and Polyampholyte N-Isopropylacrylamide-Based Hydrogels Prepared in the Presence of Imprinting Ligands: Stimuli-Responsiveness and Adsorption/Release Properties

    PubMed Central

    Lago, Miguel A.; Grinberg, Valerij Ya.; Burova, Tatiana V.; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2011-01-01

    The conformation of the imprinted pockets in stimulus-responsive networks can be notably altered when the stimulus causes a volume phase transition. Such a tunable affinity for the template molecule finds interesting applications in the biomedical and drug delivery fields. Nevertheless, the effect that the binding of the template causes on the stimuli-responsiveness of the network has barely been evaluated. In this work, the effect of two ionic drugs used as templates, namely propranolol hydrochloride and ibuprofen sodium, on the responsiveness of N-isopropylacrylamide-based hydrogels copolymerized with acrylic acid (AAc) and N-(3-aminopropyl) methacrylamide (APMA) and on their ability to rebind and to control the release of the template was evaluated. The degree of swelling and, in some cases, energetics (HS-DSC) of the transitions were monitored as a function of temperature, pH, and concentration of drug. Marked decrease in the transition temperature of the hydrogels, accompanied by notable changes in the transition width, was observed in physiological NaCl solutions and after the binding of the drug molecules, which reveals relevant changes in the domain structure of the hydrogels as the charged groups are shielded. The ability of the hydrogels to rebind propranolol or ibuprofen was quantified at both 4 and 37 °C and at two different drug concentrations, in the range of those that cause major changes in the network structure. Noticeable differences between hydrogels bearing AAc or APMA and between imprinted and non-imprinted networks were also observed during the release tests in NaCl solutions of various concentrations. Overall, the results obtained evidence the remarkable effect of the template molecules on the responsiveness of intelligent imprinted hydrogels. PMID:24956450

  1. Preparation and in vitro characterization of thermosensitive and mucoadhesive hydrogels for nasal delivery of phenylephrine hydrochloride.

    PubMed

    Xu, Xiaofeng; Shen, Yan; Wang, Wei; Sun, Chunmeng; Li, Chang; Xiong, Yerong; Tu, Jiasheng

    2014-11-01

    The aim of the present work was to develop a nasal delivery system of phenylephrine hydrochloride (PE) in spray form to make prolonged remedy of nasal congestion. The formulations contain the thermosensitive hydrogel, i.e., Poloxamer 407 (P407) and Poloxamer 188 (P188) mixtures, and mucoadhesives, i.e., ε-polylysine (ε-PL) and low molecular weight sodium hyaluronate (MW 11,000Da). The in vitro characterizations of formulations including rheology studies, texture profiles and in vitro mucoadhesion potential were investigated after gelation temperatures measurements. The results showed that the concentration of P407 or P188 had significant influence on gelation temperature and texture profiles. The addition of mucoadhesives, though lowered the gel strength of formulations, increased interaction with mucin. After screening, two formulations (i.e., 1.0% PE/0.5% ε-PL/17% P407/0.5% P188 or Formulation A; and 1.0% PE/0.5% HA/17% P407/0.8% P188 or Formulation B) presenting suitable gelation temperatures (∼32°C) were used for further studies on in vitro release behaviors and mucosa ciliotoxicity. Both formulations showed sustained release of PE for up to 8h and similar toxicity to saline, the negative control. Thus, the thermosensitive and mucoadhesive PE-containing hydrogels are promising to achieve prolonged decongestion in nasal cavity.

  2. Carbohydrazide-dependent reductant for preparing nitrogen-doped graphene hydrogels as electrode materials in supercapacitor

    NASA Astrophysics Data System (ADS)

    Jiang, Man; Xing, Ling-Bao; Zhang, Jing-Li; Hou, Shu-Fen; Zhou, Jin; Si, Weijiang; Cui, Hongyou; Zhuo, Shuping

    2016-04-01

    Three-dimensional (3D) nitrogen-doped graphene hydrogels (NGHs) are designed and synthesized in an efficient and fast way by using a strong reductant of carbohydrazide as reducing and doping agent in an aqueous solution of graphene oxide (GO). The transformation of GO suspension to the hydrogels can be completed in 1 h, which can be confirmed by X-ray powder diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). With adding different amounts of carbohydrazide, the obtained NGHs behave different doping of N and unlike performances in supercapacitors, which can be demonstrated by elemental analysis and X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), N2 sorption experiments, and electrochemical measurements, respectively. According to the network architectures, the NGHs all exhibited high specific capacitance, NGHs-1, NGHs-2, NGHs-5 and NGHs-10 showed specific capacitance at 167.7, 156.8, 140.4 and 119.3 F g-1 at 1 A g-1 in KOH electrolyte. The specific capacitance can still be maintained for 80.5, 79.5, 80.3 and 78.6% with an increase of the discharging current density of 10 A g-1, respectively. More interestingly, the NGHs-1 based supercapacitor also exhibited good electrochemical stability and high degree of reversibility in the long-term cycling test (81.5% retention after 4000 cycles).

  3. Physical properties of artificial extracellular matrix protein hydrogels prepared by thiol-maleimide chemistry

    NASA Astrophysics Data System (ADS)

    Zhang, Wenbin; Tirrell, David

    2013-03-01

    Using genetic engineering methods, telechelic proteins were designed from elastin- and fibronectin-derived repeating units and biosynthesized in E. coli. The telechelic proteins bear terminal thiols could either undergo chain-extension with bis-maleimide-functionalized poly(ethylene glycol) (MAL-PEG-MAL) or crosslinking with tetrakis-maleimide-functionalized 4-arm star PEG (star-PEG-MAL). The latter leads to protein-based hydrogels that are transparent, uniform, and highly extensible. The reaction kinetics ranges from several minutes to a few hours depending on the free-thiol content and the protein weight percentage. The mechanical properties of the gel depend on the protein content and the cross-linker concentration. It is also possible to further tune the mechanical properties by using a mixture of MAL-PEG-MAL and star-PEG-MAL for crosslinking. The water contents of the hydrogels are high, especially after swelling. The results suggest its promising application for cell encapsulation and 3D cell culture in tissue engineering.

  4. Influence of clay particles on microfluidic-based preparation of hydrogel composite microsphere

    NASA Astrophysics Data System (ADS)

    Hong, Joung Sook

    2016-05-01

    For the successful fabrication of a hydrogel composite microsphere, this study aimed to investigate the influence of clay particles on microsphere formation in a microfluidic device which has flow focusing and a 4.5:1 contraction channel. A poly alginic acid solution (2.0 wt.%) with clay particles was used as the dispersed phase to generate drops in an oil medium, which then merged with drops of a CaCl2 solution for gelation. Drop generations were observed with different flow rates and particles types. When the flow rate increased, drop generation was enhanced and drop size decreased by the build-up of more favorable hydrodynamic flow conditions to detach the droplets. The addition of a small amount of particles insignificantly changed the drop generation behavior even though it reduced interfacial tension and increased the viscosity of the solution. Instead, clays particles significantly affected hydro-gelation depending on the hydrophobicity of particles, which produced further heterogeneity in the shape and size of microsphere.

  5. Organic hydrogels as potential sorbent materials for water purification

    NASA Astrophysics Data System (ADS)

    Linardatos, George; Bekiari, Vlasoula; Bokias, George

    2014-05-01

    Hydrogels are three-dimensional, hydrophilic, polymeric networks capable to adsorb large amounts of water or biological fluids. The networks are composed of homopolymers or copolymers and are insoluble due to the presence of chemical or physical cross-links. Depending on the nature of the structural units, swelling or shrinking of these gels can be activated by several external stimuli, such as solvent, heat, pH, electric stimuli. As a consequence, these materials are attractive for several applications in a variety of fields: drug delivery, muscle mimetic soft linear actuators, hosts of nanoparticles and semiconductors, regenerative medicine etc. Of special interest is the application of hydrogels for water purification, since they can effectively adsorb several water soluble pollutants such as metal ions, inorganic or organic anions, organic dyestaff, etc. In the present work, anionic hydrogels bearing negatively charged -COO- groups were prepared and investigated. These are based on the anionic monomer sodium acrylate (ANa) and the nonionic one N,N-dimethylacrylamide (DMAM). A series of copolymeric hydrogels (P(DMAM-co-ANax) were synthesized. The molar content x of ANa units (expressing the molar charged content of the hydrogel) varies from 0 (nonionic poly(N,N-dimethylacrylamide), PDMAM, hydrogel) up to 1 (fully charged poly(sodium acrylate), PANa, hydrogel). The hydrogels were used to extract organic or inorganic solutes from water. Cationic and anionic model dyes, as well as multivalent inorganic ions, have been studied. It is found that cationic dyes are strongly adsorbed and retained by the hydrogels, while adsorbance of anionic dyes was negligible. Both maximum adsorption and equilibrium binding constant depend on the chemical structure of the dye, the presence of functional chemical groups and the hydrophobic-hydrophilic balance. In the case of metal cations, adsorption depends mostly on the charge of the cation. In addition, crucial factors controlling

  6. Adsorption of protein-coated lipid droplets to mixed biopolymer hydrogel surfaces: role of biopolymer diffusion.

    PubMed

    Vargas, Maria; Weiss, Jochen; McClements, D Julian

    2007-12-18

    The adsorption of charged particles to hydrogel surfaces is important in a number of natural and industrial processes. In this study, the adsorption of cationic lipid droplets to the surfaces of anionic hydrogels was examined. An oil-in-water emulsion containing cationic beta-lactoglobulin-coated lipid droplets was prepared (d32=0.24 microm, zeta=+74 mV, pH 3.0). An anionic hydrogel containing 0.1 wt % beet pectin and 1.5 wt % agar (pH 3.0) was prepared. Emulsions containing different lipid droplet concentrations (0.3-5 wt %) were brought into contact with the hydrogel surfaces for different times (0-24 h). The adsorption of lipid droplets to the hydrogel surfaces could not be explained by a typical adsorption isotherm. We found that the electrical charge on the nonadsorbed lipid droplets became less positive or even became negative in the presence of the hydrogel and that extensive droplet aggregation occurred, which was attributed to the ability of pectin molecules to diffuse through the hydrogels and interact with the lipid droplets. These results may have important consequences for understanding certain industrial and biological processes, as well as for the design of controlled or triggered release systems.

  7. Preparation and characterization of hybrid pH-sensitive hydrogels of chitosan-co-acrylic acid for controlled release of verapamil.

    PubMed

    Ranjha, Nazar M; Ayub, Gohar; Naseem, Shahzad; Ansari, Muhammad Tayyab

    2010-10-01

    In the present work crosslinked hydrogels based on chitosan (CS) and acrylic acid (AA) were prepared by free radical polymerization with various feed compositions using N,N methylenebisacrylamide (MBA) as crosslinking agent. Benzoyl peroxide was used as catalyst. Fourier transform infrared spectra (FTIR) confirmed the formation of the crosslinked hydrogels. This hydrogel is formed due to electrostatic interaction between cationic groups in CS and anionic groups in AA. Prepared hydrogels were used for dynamic and equilibrium swelling studies. For swelling behavior, effect of pH, polymeric and monomeric compositions and degree of crosslinking were investigated. Swelling studies were performed in USP phosphate buffer solutions of varying pH 1.2, 5.5, 6.5 and 7.5. Results showed that swelling increased by increasing AA contents in structure of hydrogels in solutions of higher pH values. This is due to the presence of more carboxylic groups available for ionization. On the other hand by increasing the chitosan content swelling increased in a solution of acidic pH, but this swelling was not significant and it is due to ionization of amine groups present in the structure of hydrogel. Swelling decreased with increase in crosslinking ratio owing to tighter hydrogel structure. Porosity and sol-gel fraction were also measured. With increase in CS and AA contents porosity and gel fraction increased, whereas by increasing MBA content porosity decreased and gel fraction increased. Furthermore, diffusion coefficient (D) and the network parameters i.e., the average molecular weight between crosslinks (M(c)), polymer volume fraction in swollen state (V(2s)), number of repeating units between crosslinks (M(r)) and crosslinking density (q) were calculated using Flory-Rehner theory. Selected samples were loaded with a model drug verapamil. Release of verapamil depends on the ratios of CS/AA, degree of crosslinking and pH of the medium. The release mechanisms were studied by fitting

  8. Enhanced ALP activity of MG63 cells cultured on hydroxyapatite-poly(ethylene glycol) hydrogel composites prepared using EDTA-OH.

    PubMed

    Ito, Temmei; Sasaki, Makoto; Taguchi, Tetsushi

    2015-03-02

    In order to obtain a hydroxyapatite (HAp)-poly(ethylene glycol) (PEG) composite, tetra amine-terminated PEG was crosslinked using disuccinimidyl tartrate to obtain a PEG hydrogel. Using two kinds of chelators with different stability constants for Ca ion (N-(2-hydroxyethyl) ethylenediamine-N,N',N'-triacetic acid (EDTA-OH, 8.14), and ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA, 10.96)), calcium phosphate was deposited within PEG hydrogels by heating the chelator-containing calcium phosphate solution at 90 °C. X-ray diffraction analysis showed that the deposited calcium phosphate was HAp. The crystallinity of the HAp deposited using EDTA-OH was low compared with that obtained using EDTA, but the amount of HAp deposited within the PEG hydrogel using EDTA-OH was higher than that deposited using EDTA. Significantly more human osteoblast-like MG-63 cells adhered on the HAp-PEG composite prepared using EDTA-OH than on the HAp-PEG composites prepared using EDTA. Furthermore, the alkaline phosphatase activity of MG-63 cultured on the HAp-PEG composite prepared using EDTA-OH was four times higher than that on the HAp-PEG composite prepared using EDTA. Therefore, the HAp-PEG composite prepared using EDTA-OH has potential as a bone substitute material.

  9. Nata de coco (NDC) hydrogel as nanoreactors for preparation iron nanoparticles (FeNps) from ferrocenium reduction

    NASA Astrophysics Data System (ADS)

    Andarini, Mellissa; Lazim, Azwan

    2014-09-01

    This study focuses on hydrogel as nano template to produce iron nanoparticles (FeNps). Radical polymerization was used to synthesize the hydrogel from nata de coco (NDC-g-PAA). Ferrocenium (FcCL) with 1 × 10-4 g/ml has successfully incorporated with NDC-g-PAA hydrogel system and reduce using sodium hydroxide (NaOH) at different concentrations. Transmission electron microscopy (TEM) result demonstrates that the size of FeNps produced was about 5 - 20 nm. Morphological analysis of hydrogel is carried out by scanning electron microscopy (SEM), SEM-EDEX is used to determine percentage of iron (Fe) in hydrogel. The results offer a wide range of application in various areas, especially the use of hydrogel system as a responsive template.

  10. Nata de coco (NDC) hydrogel as nanoreactors for preparation iron nanoparticles (FeNps) from ferrocenium reduction

    SciTech Connect

    Andarini, Mellissa; Lazim, Azwan

    2014-09-03

    This study focuses on hydrogel as nano template to produce iron nanoparticles (FeNps). Radical polymerization was used to synthesize the hydrogel from nata de coco (NDC-g-PAA). Ferrocenium (FcCL) with 1 × 10{sup −4} g/ml has successfully incorporated with NDC-g-PAA hydrogel system and reduce using sodium hydroxide (NaOH) at different concentrations. Transmission electron microscopy (TEM) result demonstrates that the size of FeNps produced was about 5 – 20 nm. Morphological analysis of hydrogel is carried out by scanning electron microscopy (SEM), SEM-EDEX is used to determine percentage of iron (Fe) in hydrogel. The results offer a wide range of application in various areas, especially the use of hydrogel system as a responsive template.

  11. High Temperature Thermosetting Polyimide Nanocomposites Prepared with Reduced Charge Organoclay

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi; Liang, Margaret I.

    2005-01-01

    The naturally occurring sodium and calcium cations found in bentonite clay galleries were exchanged with lithium cations. Following the cation exchange, a series of reduced charge clays were prepared by heat treatment of the lithium bentonite at 130 C, 150 C, or 170 C. Inductively coupled plasma (ICP) analysis showed that heating the lithium clay at elevated temperatures reduced its cation exchange capacity. Ion exchange of heat-treated clays with either a protonated alkyl amine or a protonated aromatic diamine resulted in decreasing amounts of the organic modifier incorporated into the lithium clay. The level of silicate dispersion in a thermosetting polyimide matrix was dependent upon the temperature of Li-clay heat treatment as well as the organic modification. In general, clays treated at 150 C or 170 C, and exchanged with protonated octadcylamine or protonated 2,2'-dimethlybenzidine (DMBZ) showed a higher degree of dispersion than clays treated at 130 C, or exchanged with protonated dodecylamine. Dynamic mechanical analysis showed little change in the storage modulus or T(sub g) of the nanocomposites compared to the base resin. However, long term isothermal aging of the samples showed a significant decrease in the resin oxidative weight loss. Nanocomposite samples aged in air for 1000 hours at 288 C showed of to a decrease in weight loss compared to that of the base resin. This again was dependent on the temperature at which the Li-clay was heated and the choice of organic modification.

  12. Uranyl ion uptake capacity of poly (N-isopropylacrylamide/maleic acid) copolymeric hydrogels prepared by gamma rays

    NASA Astrophysics Data System (ADS)

    Kam, Erol; Taşdelen, Betul; Osmanlioglu, A. Erdal

    2012-06-01

    The effect of gel composition, absorbed dose and pH of the solution on the uranyl ion uptake capacity of N-isopropylacrylamide/maleic acid copolymeric hydrogels containing 0-3 mol% of maleic acid at 48 kGy have been investigated. Uranyl uptake capacity of hydrogels are found to increase from 18.5 to 94.8 mg [UO22+]/g dry gel as the mole % of maleic acid content in the gel structure increased from 0 to 3. The percent swelling, equilibrium swelling and diffusion coefficient values have been evaluated for poly(N-isopropylacrylamide/maleic acid) hydrogels at 500 ppm of uranyl nitrate solution.

  13. Cyclodextrin Inclusion Polymers Forming Hydrogels

    NASA Astrophysics Data System (ADS)

    Li, Jun

    This chapter reviews the advances in the developments of supramolecular hydrogels based on the polypseudorotaxanes and polyrotaxanes formed by inclusion complexes of cyclodextrins threading onto polymer chains. Both physical and chemical supramolecular hydrogels of many different types are discussed with respect to their preparation, structure, property, and gelation mechanism. A large number of physical supramolecular hydrogels were formed induced by self-assembly of densely packed cyclodextrin rings threaded on polymer or copolymer chains acting as physical crosslinking points. The thermo-reversible and thixotropic properties of these physical supramolecular hydrogels have inspired their applications as injectable drug delivery systems. Chemical supramolecular hydrogels synthesized from polypseudorotaxanes and polyrotaxanes were based on the chemical crosslinking of either the cyclodextrin molecules or the included polymer chains. The chemical supramolecular hydrogels were often made biodegradable through incorporation of hydrolyzable threading polymers, end caps, or crosslinkers, for their potential applications as biomaterials.

  14. Preparation and characterization of a novel sodium alginate incorporated self-assembled Fmoc-FF composite hydrogel.

    PubMed

    Gong, Xiao; Branford-White, Christopher; Tao, Lei; Li, Shubai; Quan, Jing; Nie, Huali; Zhu, Limin

    2016-01-01

    Dipeptides and their derivatives have attracted tremendous attention owning to their excellent abilities of self-assemble assembling into various structures which have great potentials for applications in biology and/or nanotechnology. In the present study, we dedicate to fabricate a rigid and structure controllable Fmoc-FF/SA composite hydrogel. We found that the modified dipeptide, fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) can self-assemble into rigid hydrogels with structures of nanowires, layered thin films or honeycombs as the change of sodium alginate (SA) concentration. Meanwhile, CD-spectroscopy demonstrated that SA appeared to control the process, but it did not change the arrangement of the Fmoc-FF peptide. Our results demonstrated that the formed hydrogel showed physical and chemical stability as well as possessing good biocompatibility. Rheological measurements showed that the addition of SA could improve the stability of the hydrogel. Cell viability assay revealed that the Fmoc-FF and Fmoc-FF/SA hydrogels are both beneficial for cell proliferation in-vitro. Our results indicated that the fabricated Fmoc-FF/SA composite hydrogels could be used in tissue engineering and drug delivery in the future. PMID:26478335

  15. Preparation and characterization of a novel sodium alginate incorporated self-assembled Fmoc-FF composite hydrogel.

    PubMed

    Gong, Xiao; Branford-White, Christopher; Tao, Lei; Li, Shubai; Quan, Jing; Nie, Huali; Zhu, Limin

    2016-01-01

    Dipeptides and their derivatives have attracted tremendous attention owning to their excellent abilities of self-assemble assembling into various structures which have great potentials for applications in biology and/or nanotechnology. In the present study, we dedicate to fabricate a rigid and structure controllable Fmoc-FF/SA composite hydrogel. We found that the modified dipeptide, fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) can self-assemble into rigid hydrogels with structures of nanowires, layered thin films or honeycombs as the change of sodium alginate (SA) concentration. Meanwhile, CD-spectroscopy demonstrated that SA appeared to control the process, but it did not change the arrangement of the Fmoc-FF peptide. Our results demonstrated that the formed hydrogel showed physical and chemical stability as well as possessing good biocompatibility. Rheological measurements showed that the addition of SA could improve the stability of the hydrogel. Cell viability assay revealed that the Fmoc-FF and Fmoc-FF/SA hydrogels are both beneficial for cell proliferation in-vitro. Our results indicated that the fabricated Fmoc-FF/SA composite hydrogels could be used in tissue engineering and drug delivery in the future.

  16. Preparation and characterization of a novel micro- and nanocomposite hydrogels containing cellulosic fibrils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In recent years, the preparation of cellulosic composites and nanocomposites has become an important approach because of the wide abundance of cellulose, its biodegradability, renewability, and the ability to effectively reinforce a polymer matrix in an environmentally benign nature. The main object...

  17. The crosslinking of polysaccharides with polyamines and dextran-polyallylamine antibacterial hydrogels.

    PubMed

    O'Connor, Naphtali A; Abugharbieh, Ahmad; Yasmeen, Farzana; Buabeng, Emmanuel; Mathew, Steve; Samaroo, Diana; Cheng, Hai-Ping

    2015-01-01

    A facile modular approach to rapidly prepare pH-responsive hydrogels by crosslinking polysaccharides with polyamines is demonstrated. Hydrogels are prepared by first reacting the less reactive polysaccharides with the cross-linker epichlorohydrin and completed by the addition of polyamines. The crosslinking of polysaccharides with polyamines provides a facile method for incorporating functionality into polysaccharide based hydrogels. This process is demonstrated with the polysaccharides dextran, pullulan and carboxymethyl cellulose and with the polyamines polyallylamine and polyethylene imine. The hydrogels were characterized by FTIR and swelling studies, which showed pH-dependent swelling due to the presence of the polyamine. The hydrogels can also be tailored by varying the mass ratio between the polysaccharide and polyamine. Absorption studies of organic analytes showed the polyamine content affecting the uptake of a charged substrate (methylene blue) and no effect on a neutral substrate (6-methyl coumarin). This synthetic method was also used to prepare hydrogels with antibacterial activity against E. coli and S. aureus by utilizing an amphiphilic polyallylamine. PMID:25128095

  18. The crosslinking of polysaccharides with polyamines and dextran-polyallylamine antibacterial hydrogels.

    PubMed

    O'Connor, Naphtali A; Abugharbieh, Ahmad; Yasmeen, Farzana; Buabeng, Emmanuel; Mathew, Steve; Samaroo, Diana; Cheng, Hai-Ping

    2015-01-01

    A facile modular approach to rapidly prepare pH-responsive hydrogels by crosslinking polysaccharides with polyamines is demonstrated. Hydrogels are prepared by first reacting the less reactive polysaccharides with the cross-linker epichlorohydrin and completed by the addition of polyamines. The crosslinking of polysaccharides with polyamines provides a facile method for incorporating functionality into polysaccharide based hydrogels. This process is demonstrated with the polysaccharides dextran, pullulan and carboxymethyl cellulose and with the polyamines polyallylamine and polyethylene imine. The hydrogels were characterized by FTIR and swelling studies, which showed pH-dependent swelling due to the presence of the polyamine. The hydrogels can also be tailored by varying the mass ratio between the polysaccharide and polyamine. Absorption studies of organic analytes showed the polyamine content affecting the uptake of a charged substrate (methylene blue) and no effect on a neutral substrate (6-methyl coumarin). This synthetic method was also used to prepare hydrogels with antibacterial activity against E. coli and S. aureus by utilizing an amphiphilic polyallylamine.

  19. Hydrogel-Forming Microneedles Prepared from “Super Swelling” Polymers Combined with Lyophilised Wafers for Transdermal Drug Delivery

    PubMed Central

    Donnelly, Ryan F.; McCrudden, Maelíosa T. C.; Zaid Alkilani, Ahlam; Larrañeta, Eneko; McAlister, Emma; Courtenay, Aaron J.; Kearney, Mary-Carmel; Singh, Thakur Raghu Raj; McCarthy, Helen O.; Kett, Victoria L.; Caffarel-Salvador, Ester; Al-Zahrani, Sharifa; Woolfson, A. David

    2014-01-01

    We describe, for the first time, hydrogel-forming microneedle arrays prepared from “super swelling” polymeric compositions. We produced a microneedle formulation with enhanced swelling capabilities from aqueous blends containing 20% w/w Gantrez S-97, 7.5% w/w PEG 10,000 and 3% w/w Na2CO3 and utilised a drug reservoir of a lyophilised wafer-like design. These microneedle-lyophilised wafer compositions were robust and effectively penetrated skin, swelling extensively, but being removed intact. In in vitro delivery experiments across excised neonatal porcine skin, approximately 44 mg of the model high dose small molecule drug ibuprofen sodium was delivered in 24 h, equating to 37% of the loading in the lyophilised reservoir. The super swelling microneedles delivered approximately 1.24 mg of the model protein ovalbumin over 24 h, equivalent to a delivery efficiency of approximately 49%. The integrated microneedle-lyophilised wafer delivery system produced a progressive increase in plasma concentrations of ibuprofen sodium in rats over 6 h, with a maximal concentration of approximately 179 µg/ml achieved in this time. The plasma concentration had fallen to 71±6.7 µg/ml by 24 h. Ovalbumin levels peaked in rat plasma after only 1 hour at 42.36±17.01 ng/ml. Ovalbumin plasma levels then remained almost constant up to 6 h, dropping somewhat at 24 h, when 23.61±4.84 ng/ml was detected. This work represents a significant advancement on conventional microneedle systems, which are presently only suitable for bolus delivery of very potent drugs and vaccines. Once fully developed, such technology may greatly expand the range of drugs that can be delivered transdermally, to the benefit of patients and industry. Accordingly, we are currently progressing towards clinical evaluations with a range of candidate molecules. PMID:25360806

  20. Nanostructure controlled sustained delivery of human growth hormone using injectable, biodegradable, pH/temperature responsive nanobiohybrid hydrogel

    NASA Astrophysics Data System (ADS)

    Singh, Narendra K.; Nguyen, Quang Vinh; Kim, Bong Sup; Lee, Doo Sung

    2015-02-01

    The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new protein delivery system by the self-assembly and intercalation of a negatively charged hGH onto a positively charged 2D-layered double hydroxide nanoparticle (LDH). The LDH-hGH ionic complex, with an average particle size of approximately 100 nm, retards hGH diffusion. Nanobiohybrid hydrogels (PAEU/LDH-hGH) were prepared by dispersing the LDH-hGH complex into a cationic pH- and temperature-sensitive injectable PAEU copolymer hydrogel to enhance sustained hGH release by dual ionic interactions. Biodegradable copolymer hydrogels comprising poly(β-amino ester urethane) and triblock poly(ε-caprolactone-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-lactide) (PCLA-PEG-PCLA) were synthesized and characterized. hGH was self-assembled and intercalated onto layered LDH nanoparticles through an anion exchange technique. X-ray diffraction and zeta potential results showed that the LDH-hGH complex was prepared successfully and that the PAEU/LDH-hGH nanobiohybrid hydrogel had a disordered intercalated nanostructure. The biocompatibility of the nanobiohybrid hydrogel was confirmed by an in vitro cytotoxicity test. The in vivo degradation of pure PAEU and its nanobiohybrid hydrogels was investigated and it showed a controlled degradation of the PAEU/LDH nanobiohybrids compared with the pristine PAEU copolymer hydrogel. The LDH-hGH loaded injectable hydrogels suppressed the initial burst release of hGH and extended the release period for 13 days in vitro and 5 days in vivo. The developed nanohybrid hydrogel has the potential for application as a protein carrier to improve patient compliance.The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new

  1. Zwitterionic hydrogels: an in vivo implantation study.

    PubMed

    Zhang, Zheng; Chao, Timothy; Liu, Lingyun; Cheng, Gang; Ratner, Buddy D; Jiang, Shaoyi

    2009-01-01

    Zwitterionic hydrogels, including poly(sulfobetaine methacrylate) (polySBMA) and poly(carboxybetaine methacrylate) (polyCBMA), and co-polymeric hydrogels of CBMA and 2-hydroxyethyl methacrylate (HEMA) (poly(CBMA-co-HEMA)) were prepared. Their in vitro and in vivo properties were evaluated and compared with those of polyHEMA hydrogels. Bovine aortic endothelial cells (BAECs) were incubated with zwitterionic and polyHEMA hydrogels to evaluate their bioadhesion properties. Both polySBMA and polyCBMA hydrogels were found to be non-cytotoxic and their endotoxin levels were found to be acceptable for in vivo implantation. Results from in vivo subcutaneous implantation showed reduced cell attachment to the surfaces of polySBMA and poly(CBMA-co-HEMA) hydrogels after one-week implantation as compared with polyHEMA hydrogels. After a 4-week implantation, capsules with higher vascularities surrounding the two zwitterionic hydrogels were found. However, polyHEMA, polySBMA and poly(CBMA-co-HEMA) hydrogels showed similar capsule thicknesses and similar numbers of attached foreign body giant cells (FBGCs). In this work, zwitterionic hydrogels demonstrate healing and integration comparable to polyHEMA hydrogels, but with improved vascularity. These zwitterionic hydrogels are promising alternatives to polyHEMA hydrogels as implantable materials. PMID:19793443

  2. Preparation, characterization and protein sorption of photo-crosslinked cell membrane-mimicking chitosan-based hydrogels.

    PubMed

    Zhao, Yunfei; Ma, Liubo; Zeng, Rong; Tu, Mei; Zhao, Jianhao

    2016-10-20

    Photocrosslinkable biomimetic chitosan derivative, glycidyl methacrylate-phosphorylcholine-chitosan (PCCs-GMA) was synthesized through the combination of Atherton-Todd reaction for coupling phosphorylcholine and ring opening reaction of epoxides for attaching GMA, and confirmed by (1)H and (31)P NMR and Fourier transform infrared (FTIR) spectroscopy. The photo-crosslinking reaction of PCCs-GMA with different degree of substitution (DS) of GMA allowed the formation of biomimetic hydrogels with tunable mechanical and swelling properties. Cold crystallization behaviors ascribed to their restrained freezing bound water were investigated using differential scanning calorimetry (DSC). The rheological and swelling behaviors, hemolysis as well as protein sorption of PCCs-GMA hydrogels were investigated in terms of the DS of GMA, using fibrinogen, bovine serum albumin and lysozyme as model proteins. Low irreversible protein sorption and non hemolytic results indicated that photo-crosslinked PCCs-GMA hydrogels may offer a promising candidate material with resistance to protein fouling in biomedical applications. PMID:27474563

  3. Preparation, characterization and protein sorption of photo-crosslinked cell membrane-mimicking chitosan-based hydrogels.

    PubMed

    Zhao, Yunfei; Ma, Liubo; Zeng, Rong; Tu, Mei; Zhao, Jianhao

    2016-10-20

    Photocrosslinkable biomimetic chitosan derivative, glycidyl methacrylate-phosphorylcholine-chitosan (PCCs-GMA) was synthesized through the combination of Atherton-Todd reaction for coupling phosphorylcholine and ring opening reaction of epoxides for attaching GMA, and confirmed by (1)H and (31)P NMR and Fourier transform infrared (FTIR) spectroscopy. The photo-crosslinking reaction of PCCs-GMA with different degree of substitution (DS) of GMA allowed the formation of biomimetic hydrogels with tunable mechanical and swelling properties. Cold crystallization behaviors ascribed to their restrained freezing bound water were investigated using differential scanning calorimetry (DSC). The rheological and swelling behaviors, hemolysis as well as protein sorption of PCCs-GMA hydrogels were investigated in terms of the DS of GMA, using fibrinogen, bovine serum albumin and lysozyme as model proteins. Low irreversible protein sorption and non hemolytic results indicated that photo-crosslinked PCCs-GMA hydrogels may offer a promising candidate material with resistance to protein fouling in biomedical applications.

  4. Preparing side charging of PCM storage: theoretical and experimental investigation

    NASA Astrophysics Data System (ADS)

    Tesfay, A. H.; Hagos, F. Y.; Yohannes, K. G.; Nydal, O. J.; Kahsay, M. B.

    2015-12-01

    In Ethiopia, there is an abundant source of solar energy that is estimated to 5.3 kWh/m2/day. However, more than 90% of the society uses biomass as a main source of energy for cooking due to lack of technologies to convert this energy. Replacing these cooking activities by using renewable energy resources decreases pollution and reduces deforestation significantly. Using the solar energy in day time has no problem. For night time however, the system needs some kind of back-up system to make the daytime solar energy available. This back-up should have high-density energy storage and constant working temperature to perform a specific application. Latent heat storage using phase change materials (PCM) is one way of storing thermal energy. In the current study, a latent heat storage that uses a PCM material is used to store the solar energy aimed at utilizing solar energy for cooking Injera, main staple bread in Ethiopia. The PCM is a mixture of 60% NaNO3 and 40% KNO3 that are known as solar salts. The storage has a welded parallel aluminum fins with a gap of 40 mm in between to enhance the thermal conductivity during the charging-discharging process of the storage. The fins are extruded outside of the storage container to enable a side charging technique for the PCM. A prototype was developed with a solar salt of 17.5 kg and is tested for charging-discharging. The numerical simulation done on ANSYS and experimental results show an agreement and the system registered a 41.6% efficiency.

  5. Nanostructure controlled sustained delivery of human growth hormone using injectable, biodegradable, pH/temperature responsive nanobiohybrid hydrogel.

    PubMed

    Singh, Narendra K; Nguyen, Quang Vinh; Kim, Bong Sup; Lee, Doo Sung

    2015-02-21

    The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new protein delivery system by the self-assembly and intercalation of a negatively charged hGH onto a positively charged 2D-layered double hydroxide nanoparticle (LDH). The LDH-hGH ionic complex, with an average particle size of approximately 100 nm, retards hGH diffusion. Nanobiohybrid hydrogels (PAEU/LDH-hGH) were prepared by dispersing the LDH-hGH complex into a cationic pH- and temperature-sensitive injectable PAEU copolymer hydrogel to enhance sustained hGH release by dual ionic interactions. Biodegradable copolymer hydrogels comprising poly(β-amino ester urethane) and triblock poly(ε-caprolactone-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-lactide) (PCLA-PEG-PCLA) were synthesized and characterized. hGH was self-assembled and intercalated onto layered LDH nanoparticles through an anion exchange technique. X-ray diffraction and zeta potential results showed that the LDH-hGH complex was prepared successfully and that the PAEU/LDH-hGH nanobiohybrid hydrogel had a disordered intercalated nanostructure. The biocompatibility of the nanobiohybrid hydrogel was confirmed by an in vitro cytotoxicity test. The in vivo degradation of pure PAEU and its nanobiohybrid hydrogels was investigated and it showed a controlled degradation of the PAEU/LDH nanobiohybrids compared with the pristine PAEU copolymer hydrogel. The LDH-hGH loaded injectable hydrogels suppressed the initial burst release of hGH and extended the release period for 13 days in vitro and 5 days in vivo. The developed nanohybrid hydrogel has the potential for application as a protein carrier to improve patient compliance.

  6. Macroporous chitosan hydrogels: Effects of sulfur on the loading and release behaviour of amino acid-based compounds.

    PubMed

    Elviri, Lisa; Asadzadeh, Maliheh; Cucinelli, Roberta; Bianchera, Annalisa; Bettini, Ruggero

    2015-11-01

    Chitosan is a biodegradable, biocompatible polymer of natural origin widely applied to the preparation of functional hydrogels suitable for controlled release of drugs, peptides and proteins. Non-covalent interactions, expecially ionic interactions, are the main driver of the loading and release behaviour of amino acids or peptides from chitosan hydrogels. With the aim to improve the understanding of the mechanisms governing the behaviour of chitosan hydrogels on peptide uptake and delivery, in this paper the attention was focused on the role played by sulfur on the interactions of chitosan hydrogels with sulfur-containing amino acids (AA) and peptides. Hence, loading and release experiments on cysteine, cystine and glutathione (SH containing amino acid, dipeptide and tripeptide, respectively) as well as on glycine and valine as apolar amino acids were carried out. For these puroses, chitosan hydrogels were prepared in an easy and reproducible manner by a freeze-gelation process on a poly-L-lysine coated support. The hydrogel surface pore size, uniformity and distribution were tested. Optimal results (D50 = 26 ± 4 μm) were obtained by using the poly-L-lysine positively-charged surface. The loading results gathered evidenced that the sulfur-containing molecules presented an increased absorption both in terms of rate and extent by chitosan hydrogels with respect to nonpolar amino acids, mainly due to ionic and hydrogen bond interactions. ATR-FTIR analysis carried out on chitosan hydrogels, with and without the AA related compounds to study putative interactions, supported these apparent sulfur-dependent results. Finally, chitosan hydrogels displayed excellent retention capabilities (AA release <5%) for all AA, strongly supporting the use of chitosan hydrogels as matrix for controlled drug release.

  7. A green approach to prepare silver nanoparticles loaded gum acacia/poly(acrylate) hydrogels.

    PubMed

    Bajpai, S K; Kumari, Mamta

    2015-09-01

    In this work, gum acacia (GA)/poly(sodium acrylate) semi-interpenetrating polymer networks (Semi-IPN) have been fabricated via free radical initiated aqueous polymerization of monomer sodium acrylate (SA) in the presence of dissolved Gum acacia (GA), using N,N'-methylenebisacrylamide (MB) as cross-linker and potassium persulphate (KPS) as initiator. The semi-IPNs, synthesized, were characterized by various techniques such as X-ray diffraction (XRD), thermo gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The dynamic water uptake behavior of semi-IPNs was investigated and the data were interpreted by various kinetic models. The equilibrium swelling data were used to evaluate various network parameters. The semi-IPNs were used as template for the in situ preparation of silver nanoparticles using extract of Syzygium aromaticum (clove). The formation of silver nanoparticles was confirmed by surface plasmon resonance (SPR), XRD and transmission electron microscopy (TEM). Finally, the antibacterial activity of GA/poly(SA)/silver nanocomposites was tested against E. coli. PMID:26123815

  8. A green approach to prepare silver nanoparticles loaded gum acacia/poly(acrylate) hydrogels.

    PubMed

    Bajpai, S K; Kumari, Mamta

    2015-09-01

    In this work, gum acacia (GA)/poly(sodium acrylate) semi-interpenetrating polymer networks (Semi-IPN) have been fabricated via free radical initiated aqueous polymerization of monomer sodium acrylate (SA) in the presence of dissolved Gum acacia (GA), using N,N'-methylenebisacrylamide (MB) as cross-linker and potassium persulphate (KPS) as initiator. The semi-IPNs, synthesized, were characterized by various techniques such as X-ray diffraction (XRD), thermo gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The dynamic water uptake behavior of semi-IPNs was investigated and the data were interpreted by various kinetic models. The equilibrium swelling data were used to evaluate various network parameters. The semi-IPNs were used as template for the in situ preparation of silver nanoparticles using extract of Syzygium aromaticum (clove). The formation of silver nanoparticles was confirmed by surface plasmon resonance (SPR), XRD and transmission electron microscopy (TEM). Finally, the antibacterial activity of GA/poly(SA)/silver nanocomposites was tested against E. coli.

  9. Swelling, diffusion, network parameters and adsorption properties of IPN hydrogel of chitosan and acrylic copolymer.

    PubMed

    Mandal, Bidyadhar; Ray, Samit Kumar

    2014-11-01

    Interpenetrating network (IPN) type hydrogels of a biopolymer and a synthetic polymer were prepared from chitosan and crosslink copolymer of acrylic acid, sodium acrylate and hydroxyethyl methacrylate. Acrylic acid, sodium acrylate, hydroxyethyl methacrylate and N'N'-methylenebisacrylamide (MBA) monomers were free radically copolymerized and crosslinked in aqueous solution of chitosan. Several IPN hydrogels were prepared by varying concentrations of initiator, crosslinker (MBA) and weight% of chitosan . These hydrogels were characterized by free acid content, pH at point of zero charge (PZC), FTIR, DTA-TGA, SEM and XRD. The swelling and diffusion characteristics, network parameters and adsorption of cationic methyl violet (MV) and anionic congo red (CR) dyes by these hydrogels were studied. The hydrogels showed high adsorption (9.5-119 mg/g for CR and 9.2-98 mg/g for MV) and removal% (98-73% for CR and 94-66% for MV) over the feed concentration of 10-140 mg/l dye in water. The isotherms and kinetics of dye adsorption by the hydrogels were also studied.

  10. Preparation and Characterization of Electrospun PLCL/Poloxamer Nanofibers and Dextran/Gelatin Hydrogels for Skin Tissue Engineering

    PubMed Central

    Sun, Hui; Xu, Feng

    2014-01-01

    In this study, two different biomaterials were fabricated and their potential use as a bilayer scaffold for skin tissue engineering applications was assessed. The upper layer biomaterial was a Poly(ε-caprolactone-co-lactide)/Poloxamer (PLCL/Poloxamer) nanofiber membrane fabricated using electrospinning technology. The PLCL/Poloxamer nanofibers (PLCL/Poloxamer, 9/1) exhibited strong mechanical properties (stress/strain values of 9.37±0.38 MPa/187.43±10.66%) and good biocompatibility to support adipose-derived stem cells proliferation. The lower layer biomaterial was a hydrogel composed of 10% dextran and 20% gelatin without the addition of a chemical crosslinking agent. The 5/5 dextran/gelatin hydrogel displayed high swelling property, good compressive strength, capacity to present more than 3 weeks and was able to support cells proliferation. A bilayer scaffold was fabricated using these two materials by underlaying the nanofibers and casting hydrogel to mimic the structure and biological function of native skin tissue. The upper layer membrane provided mechanical support in the scaffold and the lower layer hydrogel provided adequate space to allow cells to proliferate and generate extracellular matrix. The biocompatibility of bilayer scaffold was preliminarily investigated to assess the potential cytotoxicity. The results show that cell viability had not been affected when cocultured with bilayer scaffold. As a consequence, the bilayer scaffold composed of PLCL/Poloxamer nanofibers and dextran/gelatin hydrogels is biocompatible and possesses its potentially high application prospect in the field of skin tissue engineering. PMID:25405611

  11. Multi-Hierarchical Self-Assembly of Collagen Mimetic Peptides into AAB Type Heterotrimers, Nanofibers and Hydrogels Driven by Charged Pair Interactions

    NASA Astrophysics Data System (ADS)

    O'Leary, Lesley Russell

    2011-12-01

    Replicating the multi-hierarchical self-assembly of collagen (peptide chain to triple helix to nanofiber and, finally, to a hydrogel) has long attracted scientists, both from the fundamental science perspective of supramolecular chemistry and for the potential biomedical applications perceived in tissue engineering. In terms of triple helical formation, collagen is the most abundant protein in the human body with at least 28 types, yet research involving collagen mimetic systems has only recently began to consider the innate ability of collagen to control helix composition and register. Collagen triple helices can be homotrimeric or heterotrimeric and while some types of natural collagen form only one specific composition of helix, others can form multiple. It is critical to fully understand and, if possible, reproduce the control that native collagen has on helix composition and register. In terms of nanofiber formation, many approaches to drive the self-assembly of synthetic systems through the same steps as natural collagen have been partially successful, but none have simultaneously demonstrated all levels of structural assembly. In this work, advancements in the ability to control helix composition and replicate the multi-hierarchical assembly of collagen are described. Both positive and negative design for the assembly of AAB type collagen heterotrimers were utilized by promoting heterotrimer formation though the use of charged amino acids to form intra-helix electrostatic interactions, while simultaneously discouraging homotrimers, resulting in the identification of multiple peptide systems with full control over the composition of the resulting triple helix. Similar salt-bridged hydrogen bonds between charged residues were incorporated into nanofiber forming peptides, one of which successfully assembled into sticky-ended triple helices, nanofibers with characteristic triple helical packing visible in the solution state, and strong hydrogels that are

  12. Morphological effect on swelling behaviour of hydrogel

    SciTech Connect

    Yacob, Norzita; Hashim, Kamaruddin

    2014-02-12

    Hydrogels are hydrophilic polymer networks that are capable of imbibing large amounts of water. In this work, hydrogels prepared from natural and synthetic polymers were irradiated by using electron beam irradiation. The morphology of hydrogel inter-polymeric network (IPN) was investigated using Scanning Electron Microscopy (SEM). The studies reveal correlations between pore sizes of IPN with degree of cross-linking. This relation also has an effect on swelling properties of the hydrogel. The results indicated that hydrogel with smaller pore size, as a result of much dense IPN, would decrease water uptake capacity. Combination of natural and synthetic polymers to form hydrogel affects the pore size and swelling property of the hydrogel as compared to each component of polymer.

  13. Morphological effect on swelling behaviour of hydrogel

    NASA Astrophysics Data System (ADS)

    Yacob, Norzita; Hashim, Kamaruddin

    2014-02-01

    Hydrogels are hydrophilic polymer networks that are capable of imbibing large amounts of water. In this work, hydrogels prepared from natural and synthetic polymers were irradiated by using electron beam irradiation. The morphology of hydrogel inter-polymeric network (IPN) was investigated using Scanning Electron Microscopy (SEM). The studies reveal correlations between pore sizes of IPN with degree of cross-linking. This relation also has an effect on swelling properties of the hydrogel. The results indicated that hydrogel with smaller pore size, as a result of much dense IPN, would decrease water uptake capacity. Combination of natural and synthetic polymers to form hydrogel affects the pore size and swelling property of the hydrogel as compared to each component of polymer.

  14. Preparation and swelling behavior of a novel self-assembled β-cyclodextrin/acrylic acid/sodium alginate hydrogel.

    PubMed

    Huang, Zhanhua; Liu, Shouxin; Zhang, Bin; Wu, Qinglin

    2014-11-26

    A novel biodegradable β-cyclodextrin/acrylic acid/sodium alginate (CSA) hydrogel with a three-dimensional network structure was self-assembled by inverse suspension copolymerization. The CSA resin was pH sensitive and had good water absorption properties in pH 6-8 buffer solutions. At a β-CD:AA:SA mass ratio of 1:9:3 the CSA water absorbency was found to be 1403 g/g and the CSA hydrogel strength was 4.968 N. In 0.005-0.1 mol/L chloride salt and sulfate salt solutions the CSA water absorbencies increased as follows: NaCl>KCl>MgCl2>CaCl2>FeCl3, and Na2SO4>K2SO4>FeSO4>Al2(SO4)3, respectively. The release of water from the CSA hydrogel occurred slowly over 120 h. The biodegradation efficiency of the resin reached 85.3% for Lentinula edodes. The super water absorbency, good salt resistance and excellent water retention properties of CSA make it suitable for application as an agricultural water retention agent in saline soils. PMID:25256504

  15. Preparation of a self-supporting cell architecture mimic by water channel confined photocrosslinking within a lamellar structured hydrogel.

    SciTech Connect

    Grubjesic, S.; Lee, B.; Seifert, S.; Firestone, M. A.

    2011-01-01

    A self-supporting biomimetic chemical hydrogel that can be reversibly swollen in water is described. An aqueous dispersion of a diacrylate end-derivatized PEO-PPO-PEO macromer, a saturated phospholipid, and a zwitterionic co-surfactant self-assembles into a multilamellar-structured physical gel at room temperature as determined by SAXS. The addition of a water soluble PEGDA co-monomer and photoinitiator within the water layers does not alter the self-assembled structure. ATR/FT-IR spectroscopy reveals that photoirradiation initiates the crosslinking between the acrylate end groups on the macromer with the PEGDA, forming a polymeric network within the aqueous domains. The primitive cytoskeleton mimic serves to stabilize the amphiphile bilayer, converting the physical gel into an elastic self-supporting chemical gel. Storage under ambient conditions causes dehydration of the hydrogel to 5 wt % water which can be reversed by swelling in water. The fully water swollen gel (85 wt % water) remains self-supporting but converts to a non-lamellar structure. As water is lost the chemical gel regains its lamellar structure. Incubation of the hydrogel in nonpolar organic solvents that do not dissolve the uncrosslinked lipid component (hexane) allow for swelling without loss of structural integrity. Chloroform, which readily solubilizes the lipid, causes irreversible loss of the lamellar structure.

  16. Electrically controlled release of sulfosalicylic acid from crosslinked poly(vinyl alcohol) hydrogel.

    PubMed

    Juntanon, Kanokporn; Niamlang, Sumonman; Rujiravanit, Ratana; Sirivat, Anuvat

    2008-05-22

    Electrically controlled drug delivery using poly(vinyl alcohol) (PVA) hydrogels as the matrix/carriers for a model drug was investigated. The drug-loaded PVA hydrogels were prepared by solution-casting using sulfosalicylic acid as the model drug and glutaraldehyde as the crosslinking agent. The average molecular weight between crosslinks, the crosslinking density, and the mesh size of the PVA hydrogels were determined from the equilibrium swelling theory as developed by Peppas and Merril, and the latter data were compared with those obtained from scanning electron microscopy. The release mechanisms and the diffusion coefficients of the hydrogels were studied using modified Franz-Diffusion cells in an acetate buffer with pH 5.5 and temperature 37 degrees C during a period of 48 h, in order to determine the effects of crosslinking ratio, electric field strength, and electrode polarity. The amounts of drug released were analyzed by UV-vis spectrophotometry. The amounts of drug released vary linearly with square root of time. The diffusion coefficients of drug-loaded PVA hydrogels decrease with increasing crosslink ratio. Moreover, the diffusion coefficients of the charged drug in the PVA hydrogels depend critically on the electric field strength between 0 and 5 V as well as on the electrode polarity. Thus, the release rate of sulfosalicylic acid can be altered and controlled precisely through electric field stimulation.

  17. Energy conversion in polyelectrolyte hydrogels

    NASA Astrophysics Data System (ADS)

    Olvera de La Cruz, Monica; Erbas, Aykut; Olvera de la Cruz Team

    Energy conversion and storage have been an active field of research in nanotechnology parallel to recent interests towards renewable energy. Polyelectrolyte (PE) hydrogels have attracted considerable attention in this field due to their mechanical flexibility and stimuli-responsive properties. Ideally, when a hydrogel is deformed, applied mechanical work can be converted into electrostatic, elastic and steric-interaction energies. In this talk, we discuss the results of our extensive molecular dynamics simulations of PE hydrogels. We demonstrate that, on deformation, hydrogels adjust their deformed state predominantly by altering electrostatic interactions between their charged groups rather than excluded-volume and bond energies. This is due to the hydrogel's inherent tendency to preserve electro-neutrality in its interior, in combination with correlations imposed by backbone charges. Our findings are valid for a wide range of compression ratios and ionic strengths. The electrostatic-energy alterations that we observe in our MD simulations may induce pH or redox-potential changes inside the hydrogels. The resulting energetic difference can be harvested, for instance, analogously to a Carnot engine, or facilitated for sensor applications. Center for Bio-inspired Energy Science (CBES).

  18. A Hydrogel Derived From Decellularized Dermal Extracellular Matrix

    PubMed Central

    Wolf, Matthew T.; Daly, Kerry A.; Brennan-Pierce, Ellen P.; Johnson, Scott A.; Carruthers, Christopher; D’Amore, Antonio; Nagarkar, Shailesh P.; Velankar, Sachin S.; Badylak, Stephen F.

    2012-01-01

    The ECM of mammalian tissues has been used as a scaffold to facilitate the repair and reconstruction of numerous tissues. Such scaffolds are prepared in many forms including sheets, powders, and hydrogels. ECM hydrogels provide advantages such as injectability, the ability to fill an irregularly shaped space, and the inherent bioactivity of native matrix. However, material properties of ECM hydrogels and the effect of these properties upon cell behavior are neither well understood nor controlled. The objective of this study was to prepare and determine the structure, mechanics, and the cell response in vitro and in vivo of ECM hydrogels prepared from decellularized porcine dermis and urinary bladder tissues. Dermal ECM hydrogels were characterized by a more dense fiber architecture and greater mechanical integrity than urinary bladder ECM hydrogels, and showed a dose dependent increase in mechanical properties with ECM concentration. In vitro, dermal ECM hydrogels supported greater C2C12 myoblast fusion, and less fibroblast infiltration and less fibroblast mediated hydrogel contraction than urinary bladder ECM hydrogels. Both hydrogels were rapidly infiltrated by host cells, primarily macrophages, when implanted in a rat abdominal wall defect. Both ECM hydrogels degraded by 35 days in vivo, but UBM hydrogels degraded more quickly, and with greater amounts of myogenesis than dermal ECM. These results show that ECM hydrogel properties can be varied and partially controlled by the scaffold tissue source, and that these properties can markedly affect cell behavior. PMID:22789723

  19. Tunable functional hydrogels formed from a versatile water-soluble chitosan.

    PubMed

    Xiao, Congming; You, Rongrui; Fan, Ying; Zhang, Yue

    2016-04-01

    A versatile water-soluble chitosan (WSC) was applied to construct two kinds of controllable functional hydrogels. Magnetic beads were prepared by physical cross-linking WSC with sodium alginate, soaking particles with ferrous chloride and being subjected to self-oxidation. Magnetic character of the beads was tunable by simply changing the initial concentration of ferrous ions. The beads could bind compounds that contained different charges. Their adsorption capacities for coomassie brilliant blue, rhodamine and hemoglobin were 1, 0.5 and 2.3mg/g respectively. Another kind of functional hydrogel was prepared through radical cross-linking reaction between WSC and a macromonomer (PVAM) derived from well-defined polyvinyl alcohol. The dynamic mechanical thermal analysis and thermogravimetric analysis results revealed that the mechanical strength and thermal stability of this hydrogel depended on the structure of PVAM. The capability to bind heavy metal ions of the hydrogel also relied on the structure of PVAM. The adsorption capacities of the hydrogels for Cu(2+) and Pb(2+) could reach 20.3 and 60.1mg/g respectively. PMID:26772916

  20. Rapidly recovering hydrogel scaffolds from self-assembling diblock copolypeptide amphiphiles

    NASA Astrophysics Data System (ADS)

    Nowak, Andrew P.; Breedveld, Victor; Pakstis, Lisa; Ozbas, Bulent; Pine, David J.; Pochan, Darrin; Deming, Timothy J.

    2002-05-01

    Protein-based hydrogels are used for many applications, ranging from food and cosmetic thickeners to support matrices for drug delivery and tissue replacement. These materials are usually prepared using proteins extracted from natural sources, which can give rise to inconsistent properties unsuitable for medical applications. Recent developments have utilized recombinant DNA methods to prepare artificial protein hydrogels with specific association mechanisms and responsiveness to various stimuli. Here we synthesize diblock copolypeptide amphiphiles containing charged and hydrophobic segments. Dilute solutions of these copolypeptides would be expected to form micelles; instead, they form hydrogels that retain their mechanical strength up to temperatures of about 90°C and recover rapidly after stress. The use of synthetic materials permits adjustment of copolymer chain length and composition, which we varied to study their effect on hydrogel formation and properties. We find that gelation depends not only on the amphiphilic nature of the polypeptides, but also on chain conformations-α-helix, β-strand or random coil. Indeed, shape-specific supramolecular assembly is integral to the gelation process, and provides a new class of peptide-based hydrogels with potential for applications in biotechnology.

  1. Carboxylated ficolls: preparation, characterization, and electrophoretic behavior of model charged nanospheres.

    PubMed

    Guo, Xuhong; Kirton, Gavin F; Dubin, Paul L

    2006-10-26

    Carboxylated ficolls were prepared as model spherical colloids of variable charge and size, with radii ranging from 3.0 to 19.3 nm. Capillary electrophoresis (CE), electrophoretic light scattering (ELS), and potentiometric titration were used to determine mobilities as a function of pH, degree of ionization alpha, and surface potential psi(0). Measured mobilities typically display a plateau at high pH, corresponding to high alpha and psi(0), confirming the general nature of this effect for charged spheres, seen also for charged dendrimers and charged latex particles. This result is examined in the context of a discontinuity in mobility predicted by the Wiersema, O'Brien, and White (WOW) theory and a more recent primitive model electrophoresis (PME) theory, in which bound counterions are considered either as point charges or as hard spheres. While no mobility maximum can be determined as expected by these two theories, our data seem more to support Belloni's theoretical expectations on charged polymers and spheres. Here we explain the mobility plateaus in terms of counterions accumulated close to the surface (surface potential-determining ions) or within the shear plane (mobility-determining ions).

  2. Hemostatic potential of natural/synthetic polymer based hydrogels crosslinked by gamma radiation

    NASA Astrophysics Data System (ADS)

    Barba, Bin Jeremiah D.; Tranquilan-Aranilla, Charito; Abad, Lucille V.

    2016-01-01

    Various raw materials and hydrogels prepared from their combination were assessed for hemostatic capability using swine whole blood clotting analysis. Initial screening showed efficient coagulative properties from κ-carrageenan and its carboxymethylated form, and α-chitosan, even compared to commercial products like QuikClot Zeolite Powder. Blending natural and synthetic polymers formed into hydrogels using gamma radiation produced materials with improved properties. KC and CMKC hydrogels were found to have the lowest blood clotting index in granulated form and had the higher capacity for platelet adhesion in foamed form compared to GelFoam. Possible mechanisms involved in the evident thrombogenicity of the materials include adsorption of platelets and related proteins that aid in platelet activation (primary hemostasis), absorption of water to concentrate protein factors that control the coagulation cascade, contact activation by its negatively charged surface and the formation of gel-blood clots.

  3. Local charge transport properties of hydrazine reduced monolayer graphene oxide sheets prepared under pressure condition

    SciTech Connect

    Ryuzaki, Sou Meyer, Jakob A. S.; Petersen, Søren; Nørgaard, Kasper; Hassenkam, Tue; Laursen, Bo W.

    2014-09-01

    Charge transport properties of chemically reduced graphene oxide (RGO) sheets prepared by treatment with hydrazine were examined using conductive atomic force microscopy. The current-voltage (I-V) characteristics of monolayer RGO sheets prepared under atmospheric pressure followed an exponentially increase due to 2D variable-range hopping conduction through small graphene domains in an RGO sheet containing defect regions of residual sp{sup 3} carbon clusters bonded to oxygen groups, whereas RGO sheets prepared in a closed container under moderate pressure showed linear I-V characteristics with a conductivity of 267.2−537.5 S/m. It was found that the chemical reduction under pressure results in larger graphene domains (sp{sup 2} networks) in the RGO sheets when compared to that prepared under atmospheric pressure, indicating that the present reduction of GO sheets under the pressure is one of the effective methods to make well-reduced GO sheets.

  4. Charge Retention by Gold Clusters on Surfaces Prepared Using Soft Landing of Mass Selected Ions

    SciTech Connect

    Johnson, Grant E.; Priest, Thomas A.; Laskin, Julia

    2012-01-24

    Monodisperse gold clusters have been prepared on surfaces in different charge states through soft landing of mass-selected ions. Ligand-stabilized gold clusters were prepared in methanol solution by reduction of chloro(triphenylphosphine)gold(I) with borane tert-butylamine complex in the presence of 1,3-bis(diphenylphosphino)propane. Electrospray ionization was used to introduce the clusters into the gas-phase and mass-selection was employed to isolate a single ionic cluster species (Au11L53+, L = 1,3-bis(diphenylphosphino)propane) which was delivered to surfaces at well controlled kinetic energies. Using in-situ time of flight secondary ion mass spectrometry (TOF-SIMS) it is demonstrated that the Au11L53+ cluster retains its 3+ charge state when soft landed onto the surface of a 1H,1H,2H,2H-

  5. Self-Activated Healable Hydrogels with Reversible Temperature Responsiveness.

    PubMed

    Chang, Ruixue; Wang, Xuemeng; Li, Xu; An, Heng; Qin, Jianglei

    2016-09-28

    The self-healable polymer hydrogel along with reversible temperature responsiveness was prepared through self-catalyzed dynamic acylhydrazone formation and exchange without any additional stimulus or catalyst. The hydrogel was prepared from a copolymer of N-isopropylacrylamide and acylhydrazine P(NIPAM-co-AH) cross-linked by PEO dialdehyde. Besides self-healed under catalysis of acid and aniline, the hydrogel can also self-heal activated by excess of acylhydrazine groups. Without interference of catalyst during the hydrogel formation and self-healing, this kind of hydrogel prepared from biocompatible polymers can be used in more areas including biotechnology and be more persistent. The hydrogel with a large part of the PNIPAM segment also showed temperature responsiveness around body temperature influenced by the variation in group ratio. This self-healable hydrogel has great potential application in areas related to bioscience and biotechnology. PMID:27589014

  6. Synthesis and degradation test of hyaluronic acid hydrogels.

    PubMed

    Hahn, Sei Kwang; Park, Jung Kyu; Tomimatsu, Takashi; Shimoboji, Tsuyoshi

    2007-03-10

    Hyaluronic acid (HA) hydrogels prepared with three different crosslinking reagents were assessed by in vitro and in vivo degradation tests for various tissue engineering applications. Adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and used for the preparation of methacrylated HA (HA-MA) with methacrylic anhydride and thiolated HA (HA-SH) with Traut's reagent (imminothiolane). (1)H NMR analysis showed that the degrees of HA-ADH, HA-MA, and HA-SH modification were 69, 29, and 56 mol%, respectively. HA-ADH hydrogel was prepared by the crosslinking with bis(sulfosuccinimidyl) suberate (BS(3)), HA-MA hydrogel with dithiothreitol (DTT) by Michael addition, and HA-SH hydrogel with sodium tetrathionate by disulfide bond formation. According to in vitro degradation tests, HA-SH hydrogel was degraded very fast, compared to HA-ADH and HA-MA hydrogels. HA-ADH hydrogel was degraded slightly faster than HA-MA hydrogel. Based on these results, HA-MA hydrogels and HA-SH hydrogels were implanted in the back of SD rats and their degradation was assessed according to the pre-determined time schedule. As expected from the in vitro degradation test results, HA-SH hydrogel was in vivo degraded completely only in 2 weeks, whereas HA-MA hydrogels were degraded only partially even in 29 days. The degradation rate of HA hydrogels were thought to be controlled by changing the crosslinking reagents and the functional group of HA derivatives. In addition, the state of HA hydrogel was another factor in controlling the degradation rate. Dried HA hydrogel at 37 degrees C for a day resulted in relatively slow degradation compared to the bulk HA hydrogel. There was no adverse effect during the in vivo tests. PMID:17101173

  7. Cholesterol derivatives based charged liposomes for doxorubicin delivery: preparation, in vitro and in vivo characterization.

    PubMed

    Nie, Yu; Ji, Li; Ding, Hong; Xie, Li; Li, Li; He, Bin; Wu, Yao; Gu, Zhongwei

    2012-01-01

    Cholesterol plays a critical role in liposome composition. It has great impact on the behavior of liposome in vitro and in vivo. In order to verify the possible effects from cholesterol charge, surface shielding and chemical nature, two catalogs of liposomes with charged and PEGylated cholesterols were synthesized. Anionic liposomes (AL) and cationic liposomes (CL) were prepared, with charges from hemisuccinate and lysine in cholesterol derivatives, respectively. Characteristics of different formulated liposomes were investigated after doxorubicin encapsulation, using neutral liposomes (NL) as control. Results showed that after PEGylation, AL and CL liposomes displayed prolonged retention release profile, while kept similar size distribution, encapsulation efficiency, low cytotoxicity and hemolysis comparing with NL. Confocal laser scanning microscopy and flow cytometry experiments confirmed the significantly higher cell uptake from AL and CL vesicles than the NL in mouse breast carcinoma and melanoma cells, human epithelial carcinoma and hepatoma cells. It was in accordance with our corresponding cellular mortality studies of DOX-loaded liposomes. The in vivo anti-tumor effect experiments from charged liposomes also presented much higher tumor inhibition effect (70% vs 45%, p < 0.05) than NL liposomes. This is the first time reporting anti-cancer effect from charged cholesterol liposome with/without PEGylation. It may give deeper understanding on the liposome formulation which is critical for liposome associated drug research and development.

  8. Cholesterol Derivatives Based Charged Liposomes for Doxorubicin Delivery: Preparation, In Vitro and In Vivo Characterization

    PubMed Central

    Nie, Yu; Ji, Li; Ding, Hong; Xie, Li; Li, Li; He, Bin; Wu, Yao; Gu, Zhongwei

    2012-01-01

    Cholesterol plays a critical role in liposome composition. It has great impact on the behavior of liposome in vitro and in vivo. In order to verify the possible effects from cholesterol charge, surface shielding and chemical nature, two catalogs of liposomes with charged and PEGylated cholesterols were synthesized. Anionic liposomes (AL) and cationic liposomes (CL) were prepared, with charges from hemisuccinate and lysine in cholesterol derivatives, respectively. Characteristics of different formulated liposomes were investigated after doxorubicin encapsulation, using neutral liposomes (NL) as control. Results showed that after PEGylation, AL and CL liposomes displayed prolonged retention release profile, while kept similar size distribution, encapsulation efficiency, low cytotoxicity and hemolysis comparing with NL. Confocal laser scanning microscopy and flow cytometry experiments confirmed the significantly higher cell uptake from AL and CL vesicles than the NL in mouse breast carcinoma and melanoma cells, human epithelial carcinoma and hepatoma cells. It was in accordance with our corresponding cellular mortality studies of DOX-loaded liposomes. The in vivo anti-tumor effect experiments from charged liposomes also presented much higher tumor inhibition effect (70% vs 45%, p < 0.05) than NL liposomes. This is the first time reporting anti-cancer effect from charged cholesterol liposome with/without PEGylation. It may give deeper understanding on the liposome formulation which is critical for liposome associated drug research and development. PMID:23227125

  9. Conductive hydrogel containing 3-ionene

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Yen, Shiao-Ping Siao (Inventor)

    1977-01-01

    Cationic polyelectrolytes formed by the polymerization in absence of oxygen of a monomer of the general formula: dispersed ##STR1## where x is 3 or more than 6 and Z is I, Br or Cl to form high charge density linear polymers are dispered in a water-soluble polymer such as polyvinyl alcohol to form a conductive hydrogel.

  10. Enzyme-sensing chitosan hydrogels.

    PubMed

    Sadat Ebrahimi, Mir Morteza; Schönherr, Holger

    2014-07-01

    We report on a chitosan hydrogel-based platform for the detection of enzymes, which is compatible with the implementation in infection-sensing wound dressings. Thin films of the established wound dressing biopolymer chitosan were functionalized with a fluorogenic substrate, which is released upon enzymatic degradation, resulting in a pronounced increase in fluorescence emission intensity. In this first model study, the fluorogenic substrate alanyl-alanyl-phenylalanine-7-amido-4-methylcoumarin (AAP-AMC) was covalently conjugated via amide bond formation to chitosan and was shown to facilitate the detection of the serine protease α-chymotrypsin. Systematic investigations established the dependence of hydrogel thickness and substrate loading on the hydrogel preparation conditions, as well as the dependence of the rate of the reaction on the initial enzyme concentration and the loading of AAP-AMC in the hydrogel. The initial release rate of the fluorophore 7-AMC was found to be linear with enzyme concentration and substrate loading and was independent of hydrogel thickness. Under optimized conditions the hydrogel reports the presence of α-chymotrypsin in <5 min with a limit of detection of ≤10 nM. This generic approach, which can be adapted to detect different kinds of enzymes by using appropriate fluorogenic or chromogenic substrates, is highly interesting for targeting the detection of specific pathogenic bacteria, e.g., in wound dressings. PMID:24914451

  11. Stable environmentally sensitive cationic hydrogels for controlled delivery applications.

    PubMed

    Deo, Namita; Ruetsch, S; Ramaprasad, K R; Kamath, Y

    2010-01-01

    New thermosensitive, cationic hydrogels were synthesized by the dispersion copolymerization of N-isopropylacrylamide (NIPAM) and (3-acrylamidopropyl)trimethylammonium chloride (AAPTAC). In the polymerization protocol, an amide-based comonomer, (3-acrylamidopropyl)trimethylammonium chloride, was reacted as a new alternative monomer for introducing positive charges into the thermosensitive hydrogel. The hydrogels were synthesized without making any pH adjustment in the aqueous medium. These hydrogel particles exhibited colloidal stability in the pH range of 1.5 to 11.0, while similar cationic hydrogels were reported to be unstable at pHs higher than 6. The stronger cationic character of the selected comonomer provided higher colloidal stability to the poly(NIPAM-co-AAPTAC) hydrogels. Furthermore, these hydrogels displayed sensitivity towards temperature, pH, and salt concentration. Interestingly, the particle size of hydrogels was found to be decreased significantly with an increase in temperature and salt concentration. In addition, using pyrene fluorescence spectroscopy, it was established that the hydrophobicity/hydrophilicity of the hydrogel particles was largely controlled by both pH and temperature. The thermosensitive hydrogels reported in this paper may be suitable for delivering different actives for cosmetic and medical applications. Although direct application of these hydrogel particles in cosmetics has not been shown at this stage, the methodology of making them and controlling their absorption and release properties as a function of temperature and pH has been demonstrated. Furthermore, these hydrogels may also have applications in scavenging organic and inorganic toxics.

  12. Magnetic hydrogel with high coercivity

    SciTech Connect

    Sözeri, H.; Alveroğlu, E.; Kurtan, U.; Şenel, M.; Baykal, A.

    2013-08-01

    Highlights: • Polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles have been prepared. • Magnetization measurements reveal that hydrogels have hard magnetic properties with high coercivity. • Magnetic nanoparticles makes the gel more homogeneous and do not diffuse out of the gel during water intake. • These gels are useful in applications as wastewater treatment once gels are magnetized before its usage. - Abstract: This study investigates the synthesis and characterization of polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles. Structural, electrical, and magnetic characterization of the gels have been performed with X-ray powder diffractometry, scanning electron microscopy, DC conductivity, magnetization and fluorescence spectroscopy techniques. The preparation and characterization of polyacrylamide (PAAm) hydrogels that contain 5 and 10 mg BaFe{sub 12}O{sub 19} (16 and 21 nm diameter) nanoparticles are described herein. It is seen from the fluorescence spectra that, nanoparticles surrounded to pyranine molecules so that some of pyranine molecules could not bound to the polymer strands. Electrical measurements show that presence of nanoparticles make the gel more homogeneous. Magnetization measurements reveal that hydrogels have hard magnetic properties with quite high coercivity of 4.2 kOe, which does not change with swelling. This feature makes these gels useful in applications as wastewater treatment if they are magnetized before use.

  13. One-pot synthesis of 3-dimensional reduced graphene oxide-based hydrogel as support for microbe immobilization and BOD biosensor preparation.

    PubMed

    Liu, Ling; Zhai, Junfeng; Zhu, Chengzhou; Gao, Ying; Wang, Yue; Han, Yanchao; Dong, Shaojun

    2015-01-15

    We report a hydrothermal method to prepare reduced graphene oxide (rGO)-based hydrogel (Gel(rGONR)), using neutral red (NR) to mediate the assembly of rGO sheets and tune the pore size of Gel(rGONR). A series of techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy and BET were employed to characterize the physico-chemical properties of Gel(rGONR). A large pore size of up to 20 µm and interconnected porous structure of Gel(rGONR) were obtained. Gel(rGONR) was used as a support for immobilizing microbe (denoted as Gel(rGONR-M)), which showed ~3.3 times more load mass of microbe than commonly used supports (i.e., activated carbon and carbon fiber felt) and 2.5 times higher biodegradation efficiency (BE) than carbon fiber felt. Further use of Gel(rGONR-M) as a biocatalyst for establishing a BOD biosensor exhibits a linear range of 2-64 mg O L(-1) and a detection limit 0.4 mg O L(-1) for glucose-glutamic acid (GGA). Moreover, our proposed BOD detection strategy shows a long-term viability over one year and stability up to 2 months with a relative standard deviation of 2.1%. Our results demonstrated the great potential of employing Gel(rGONR) as a microbe-immobilization support for biosensor development.

  14. Tunable drug-loading capability of chitosan hydrogels with varied network architectures.

    PubMed

    Tronci, Giuseppe; Ajiro, Hiroharu; Russell, Stephen J; Wood, David J; Akashi, Mitsuru

    2014-02-01

    Advanced bioactive systems with defined macroscopic properties and spatio-temporal sequestration of extracellular biomacromolecules are highly desirable for next generation therapeutics. Here, chitosan (CT) hydrogels were prepared with neutral or negatively charged cross-linkers in order to promote selective electrostatic complexation with charged drugs. CT was functionalized with varied dicarboxylic acids, such as tartaric acid, poly(ethylene glycol) bis(carboxymethyl) ether, 1,4-phenylenediacetic acid and 5-sulfoisophthalic acid monosodium salt (PhS), whereby PhS was hypothesized to act as a simple mimetic of heparin. Attenuated total reflectance Fourier transform infrared spectroscopy showed the presence of CO amide I, N-H amide II and CO ester bands, providing evidence of covalent network formation. The cross-linker content was reversely quantified by proton nuclear magnetic resonance on partially degraded network oligomers, so that 18 mol.% PhS was exemplarily determined. Swellability (SR: 299 ± 65-1054 ± 121 wt.%), compressibility (E: 2.1 ± 0.9-9.2 ± 2.3 kPa), material morphology and drug-loading capability were successfully adjusted based on the selected network architecture. Here, hydrogel incubation with model drugs of varied electrostatic charge, i.e. allura red (AR, doubly negatively charged), methyl orange (MO, negatively charged) or methylene blue (MB, positively charged), resulted in direct hydrogel-dye electrostatic complexation. Importantly, the cationic compound, MB, showed different incorporation behaviours, depending on the electrostatic character of the selected cross-linker. In light of this tunable drug-loading capability, these CT hydrogels would be highly attractive as drug reservoirs towards e.g. the fabrication of tissue models in vitro.

  15. Catalytic cracking with zeolite-containing silica-alumina hydrogel catalyst

    SciTech Connect

    Kuehl, G.H.; Sherry, H.S.

    1980-08-26

    A specially prepared zeolite-containing silica-alumina hydrogel gives a catalyst that is attrition resistant, more active catalytically, more selective and more stable. The hydrogel is prepared by steps including nozzle mixing of reactants to form a hydrogel, ion exchanging with ammonium, aluminum and rare earth ions, washing, drying and impregnating with rare earths.

  16. Anionic and cationic dextran hydrogels for post-loading and release of proteins.

    PubMed

    Schillemans, Joris P; Verheyen, Ellen; Barendregt, Arjan; Hennink, Wim E; Van Nostrum, Cornelus F

    2011-03-30

    In this study, post-loading of proteins in and release from chemically crosslinked dextran hydrogels exploiting reversible electrostatic interactions was investigated. Methacrylated dextran (Dex-MA) was co-polymerized with methacrylic acid (MA) or dimethylaminoethyl methacrylate (DMAEMA) to form negatively and positively charged hydrogels, respectively. Incubation of negatively charged hydrogels in a low ionic strength (10 mM HEPES, pH 7.4) solution of cytochrome C (isoelectric point (pI) 10.2) led to quantitative absorption of the protein in the hydrogel. BSA (pI 4.8) and myoglobin (pI 7.2) were post-loaded into positively charged gels at neutral pH and negatively charged gels at pH 5, respectively. Loading efficiency and protein distribution in the gels were dependent on network charge (maximum loading efficiency at 100-150 μmol charged monomer/g gel) and crosslink density (higher and more homogenous loading at lower crosslink density) and on the ionic strength during loading (lower but more homogenous loading at higher ionic strength). Diffusion controlled release of the loaded protein was triggered by incubation of the hydrogel in HEPES buffered saline (HBS) pH 7.4. The amount of released cytochrome C in HBS varied from 94% to 70% from gels containing 60 and 150 MA/g, respectively. Importantly, quantitative release was obtained in 1 M NaCl, indicating that post-loading led to neither the formation of insoluble protein aggregates nor irreversible immobilization of the protein in the matrix. ESI-MS analysis of the released cytochrome C revealed that post-loading did not result in oxidation of the protein, as opposed to loading during preparation of the gels. In conclusion, this paper shows that post-loading of proteins in dextran hydrogels and release exploiting reversible charge interactions can be applied for efficient loading of proteins that are negative, positive or neutral at physiological pH. Importantly, our data demonstrate that using this loading

  17. Hydrogel-elastomer composite biomaterials: 3. Effects of gelatin molecular weight and type on the preparation and physical properties of interpenetrating polymer networks.

    PubMed

    Peng, Henry T; Martineau, Lucie; Shek, Pang N

    2008-03-01

    To optimize the preparation of a gelatin-HydroThane Interpenetrating Polymer Network (IPN) and obtain optimum physical properties for its use as a wound dressing, we studied IPN films prepared with two types of gelatin having different molecular weights. The effects of the gelatin molecular weight and type on the IPN film's structure, morphology, swelling and mechanical properties were determined. While FTIR did not reveal any noticeable differences between the IPNs prepared using different gelatin, light microscopy showed a lesser phase separation of the film prepared with a high-molecular-weight type A gelatin. Furthermore, these films displayed slightly less swelling, higher strength and lower strain, compared to the IPNs prepared with either low-molecular-weight type A or type B gelatin. The IPN prepared with type B gelatin showed higher swelling in serum-containing medium than those prepared with type A gelatin, because of its ionic charges under the condition. Increases in viscosity were observed with increasing molecular weight, type A being more viscous than type B gelatin despite having a lower bloom number. The viscosity of the high-molecular-weight gelatin was in the same magnitude as that of HydroThane, which might lead to less phase separation. A better understanding of the effects of alterations in the gelatin molecular weight and type on the formation and properties of the gelatin-HydroThane IPN should facilitate the development of promising composite biomaterials for wound dressing applications. PMID:17665128

  18. Silk hydrogel for cartilage tissue engineering

    PubMed Central

    Chao, Pen-Hsiu Grace; Yodmuang, Supansa; Wang, Xiaoqin; Sun, Lin; Kaplan, David L.; Vunjak-Novakovic, Gordana

    2011-01-01

    Cartilage tissue engineering based on cultivation of immature chondrocytes in agarose hydrogel can yield tissue constructs with biomechanical properties comparable to native cartilage. However, agarose is immunogenic and non-degradable, and our capability to modify the structure, composition, and mechanical properties of this material is rather limited. In contrast, silk hydrogel is biocompatible and biodegradable, and it can be produced using a water-based method without organic solvents that enables precise control of structural and mechanical properties in a range of interest for cartilage tissue engineering. We observed that one particular preparation of silk hydrogel yielded cartilaginous constructs with biochemical content and mechanical properties matching constructs based on agarose. This finding and the possibility to vary the properties of silk hydrogel motivated this study of the factors underlying the suitability of hydrogels for cartilage tissue engineering. We present data resulting from a systematic variation of silk hydrogel properties, silk extraction method, gel concentration, and gel structure. Data suggest that silk hydrogel can be used as a tool for studies of the hydrogel-related factors and mechanisms involved in cartilage formation, as well as a tailorable and fully degradable scaffold for cartilage tissue engineering. PMID:20725950

  19. Reduction of postsurgical adhesion formation with hydrogels synthesized by radiation

    NASA Astrophysics Data System (ADS)

    Nho, Young-Chang; Lee, Joon-Ho

    2005-07-01

    Biocompatible and biodegradable hydrogels based on carboxymethyl cellulose (CMC) and polyethyleneglycol (PEG) were prepared as physical barriers for preventing surgical adhesions. These interpolymeric hydrogels were synthesized by gamma irradiation crosslinking technique. A 1.5 cm × 1.5 cm of cecal serosa and an adjacent abdominal wall were abraded with bone burr until the serosal surface was disrupted and hemorrhagic but not perforated. The denuded cecum was covered with either CMC/PEG hydrogels or a solution from a CMC/PEG hydrogel. Control rat serosa was not covered. Two weeks later, the rats were sacrificed and the adhesion was scored on a 0-5 scale. Control rat showed a significantly higher incidence of adhesions than either the CMC/PEG hydrogels or a solution from the CMC/PEG hydrogel. In conclusion, these studies demonstrate that CMC/PEG hydrogels have a function of the prevention for an intra abdominal adhesion in a rat model.

  20. Triethyl orthoformate mediated a novel crosslinking method for the preparation of hydrogels for tissue engineering applications: characterization and in vitro cytocompatibility analysis.

    PubMed

    Yar, Muhammad; Shahzad, Sohail; Siddiqi, Saadat Anwar; Mahmood, Nasir; Rauf, Abdul; Anwar, Muhammad Sabieh; Chaudhry, Aqif Anwar; Rehman, Ihtesham ur

    2015-11-01

    This paper describes the development of a new crosslinking method for the synthesis of novel hydrogel films from chitosan and PVA for potential use in various biomedical applications. These hydrogel membranes were synthesized by blending different ratios of chitosan (CS) and poly(vinyl alcohol) (PVA) solutions and were crosslinked with 2.5% (w/v) triethyl orthoformate (TEOF) in the presence of 17% (w/v) sulfuric acid. The physical/chemical interactions and the presence of specific functional groups in the synthesized materials were evaluated by Fourier transform infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) proved that these crosslinked hydrogel films have good thermal stability which was decreased as the CS ratio was increased. Differential scanning calorimetry (DSC) exhibited that CS and PVA were present in the amorphous form. The solution absorption properties were performed in phosphate buffer saline (PBS) solution of pH7.4. The 20% PVA-80% CS crosslinked hydrogel films showed a greater degree of solution absorption (183%) as compared to other compositions. The hydrogels with greater CS concentration (60% and 80%) demonstrated relatively more porous structure, better cell viability and proliferation and also revealed good blood clotting ability even after crosslinking. Based on the observed facts these hydrogels can be tailored for their potential utilization in wound healing and skin tissue engineering applications. PMID:26249576

  1. The effect of the physicochemical properties of bioactive electroconductive hydrogels on the growth and proliferation of attachment dependent cells.

    PubMed

    Kotanen, Christian N; Wilson, A Nolan; Dong, Chenbo; Dinu, Cerasela-Zoica; Justin, Gusphyl A; Guiseppi-Elie, Anthony

    2013-09-01

    The physicochemical properties of soft electrode materials for the abio-bio interface of advanced biosensors and next generation bionic devices in the form of electroconductive hydrogels (ECH) of interpenetrating networks of polypyrrole formed within poly(hydroxyethylmethacrylate)-based hydrogels were examined. The 1.5 mol% UV-crosslinked tetraethyleneglycol diacrylate (TEGDA) (step 1) poly(HEMA) and the electropolymerized (step 2) polypyrrole co-networks were covalently joined by the inclusion of a bifunctional monomer (1.5 mol%), 2-methacryloyloxyethyl-4(3-pyrrolyl)butanate (MPB) that served to covalently link the two networks. The optical absorbance, degree of hydration, the frequency dependent electrical impedance and the elastic modulus were examined as a function of electropolymerization charge density (step 2) (1-900 mC/cm(2)) used to prepare the linked, interpenetrating co-networks. The absorption at 430 nm showed a monotonic increase with electropolymerization charge density and correlated with the increase in elastic modulus [56 (± 32)-499 (± 293) kPa], the decrease in % hydration (68-0%) and the decrease in membrane electrical resistance. Polypyrrole (PPy) grows initially from the gel-electrode interface to fill voids within the hydrogel and ultimately onto the surface of the hydrogel. Growth of attachment dependent Rhabdomyosarcoma (RMS13) and pheochromocytoma (PC 12) cells reflects this evolution, showing an increase to a maximal value and then to decrease again at high electropolymerization charge density.

  2. Synthesis of superporous hydrogels: hydrogels with fast swelling and superabsorbent properties.

    PubMed

    Chen, J; Park, H; Park, K

    1999-01-01

    We have been interested in the synthesis of hydrogels with fast swelling kinetics and superabsorbent properties. To increase the water absorption rate, interconnected pores were introduced to the hydrogels. Since the pore size in the dried hydrogels is in the order of hundreds of micrometers, these hydrogels are called "superporous" hydrogels. Superporous hydrogels were synthesized by crosslinking polymerization of various vinyl monomers in the presence of gas bubbles formed by the chemical reaction of acid and NaHCO3. The polymerization process was optimized to capture the gas bubbles inside the synthesized hydrogels. The use of the NaHCO3/acid system allowed easy control of timing for gelation and foam formation. We found that PF127 was the best foam stabilizer for most of the monomer systems used in our study. Scanning electron microscope (SEM) pictures showed interconnected pores forming capillary channels. The capillary channels, which were critical for fast swelling, were preserved during drying by dehydrating water-swollen hydrogels with ethanol before drying. The ethanol-dehydrated superporous hydrogels reached equilibrium swelling within minutes. The equilibrium swelling time could be reduced to less than a minute with the use of a wetting agent. In our study, water moisture was used as a wetting agent since the amount of moisture content in the dried hydrogels easily could be controlled. Preparation of superporous hydrogels using the right blowing system, foam stabilizer, drying method, and wetting agent makes it possible to reduce the swelling time to less than a minute regardless of the size of the dried gels. The superporous hydrogels can be used where fast swelling and superabsorbent properties are critical.

  3. Thermally Tunable Hydrogels Displaying Angle-Independent Structural Colors.

    PubMed

    Ohtsuka, Yumiko; Seki, Takahiro; Takeoka, Yukikazu

    2015-12-14

    We report the preparation of thermally tunable hydrogels displaying angle-independent structural colors. The porous structures were formed with short-range order using colloidal amorphous array templates and a small amount of carbon black (CB). The resultant porous hydrogels prepared using colloidal amorphous arrays without CB appeared white, whereas the hydrogels with CB revealed bright structural colors. The brightly colored hydrogels rapidly changed hues in a reversible manner, and the hues varied widely depending on the water temperature. Moreover, the structural colors were angle-independent under diffusive lighting because of the isotropic nanostructure generated from the colloidal amorphous arrays. PMID:26503915

  4. Thermally Tunable Hydrogels Displaying Angle‐Independent Structural Colors

    PubMed Central

    Ohtsuka, Yumiko; Seki, Takahiro

    2015-01-01

    Abstract We report the preparation of thermally tunable hydrogels displaying angle‐independent structural colors. The porous structures were formed with short‐range order using colloidal amorphous array templates and a small amount of carbon black (CB). The resultant porous hydrogels prepared using colloidal amorphous arrays without CB appeared white, whereas the hydrogels with CB revealed bright structural colors. The brightly colored hydrogels rapidly changed hues in a reversible manner, and the hues varied widely depending on the water temperature. Moreover, the structural colors were angle‐independent under diffusive lighting because of the isotropic nanostructure generated from the colloidal amorphous arrays. PMID:26503915

  5. Zinc/hydrogel system for cathodic protection of reinforced concrete structures

    SciTech Connect

    Bennett, J.; Firlotte, C.

    1997-03-01

    Zinc, aluminum, and several aluminum alloys were tested as anodes in contact with hydrogel adhesives. Zinc was found to offer the best combination of working potential, resistance to passivation, cost, and availability. Several hydrogels used for medical applications were found to be inadequate for this use, but a hydrogel adhesive was developed specifically to bond sacrificial anodes to concrete. This hydrogel achieve a total charge in accelerated testing equal to 12 years of life at current densities normally used for cathodic protection (CP).

  6. Preparation of C{sub 60} charge transfer complexes with organic donor molecules and alkali doping

    SciTech Connect

    Otsuka, A.; Saito, G.; Hirate, S.; Pac, S.; Ishida, T.; Zakhidov, A.A.; Yakushi, K.

    1998-07-01

    Solid charge transfer (CT) complexes of C{sub 60} with TseC{sub 1}-TTF, EDT-TTF, EOET-TTF, and TDAP (1, 3, 6, 8-tetrakis(dimethylamino)pyrene) were newly prepared. All the obtained black crystals were proved to be neutral despite their rather strong electron donor ability. Lattice parameters of them except for EOET-TTF complex were determined together with those of HMTTeF{center_dot}C{sub 60}, which had been reported with different values. Rubidium doping under a mild condition was examined on the complexes of TDAP, EOET-TTF, HMTTeF, BEDT-TTF, hydroquinone and ferrocene to search for the superconductors of new crystal and electronic structures. Among them, the rubidium-doped ferrocene complex easily showed an apparent superconducting signal in SQUID magnetization measurements. The doping effect on these CT complexes is compared to that on OMTTF complex.

  7. [Preparation of recombinant serpins B3 and B4 and investigation of their specific interactions with antibodies using hydrogel-based microarrays].

    PubMed

    Butvilovskaya, V I; Tsybulskaya, M V; Tikhonov, A A; Talibov, V O; Belousov, P V; Sazykin, A Yu; Schwartz, A M; Putlyaeva, L V; Surzhikov, S A; Stomakhin, A A; Solopova, O N; Rubina, A Yu

    2015-01-01

    The objective of this work was to obtain preparations of recombinant squamous-cell carcinoma antigens (serpins B3 and B4) and to investigate their interactions with different monoclonal antibodies using hydrogel-based microarrays (biochips). Two genetic constructs encoding full-length serpin B3 and serpin B4 molecules were created to produce recombinant SPB3 and SPB4 proteins carrying a N-terminal His6-tag. Monoclonal antibodies against serpin B3 (H3, C5, H5, H81, and G9) were also obtained. An experimental gel-based biological microchip was designed to contain gel elements that carry immobilized antibodies against SPB3, immobilized commercial monoclonal SCC107 and SCC140 antibodies against squamous-cell carcinoma antigen (SCCA), and gel elements with immobilized SPB3 or SPB4. Judging by the specificity of recombinant SPB3 and SPB4, which bind to monoclonal antibodies against SCCA and, according to the manufacturer's data, can recognize conformational epitopes of both SPB3 and SPB4, it was concluded that the obtained recombinant serpins had the correct tertiary structure. A biochip-based direct immunoassay showed that SPB4 could bind effectively only to SCC107 and SCC140 antibodies, while SPB3 interacted specifically not only with these antibodies, but also with H3 and C5 monoclonal antibodies. Using biochip-based sandwich immunoassay, a pair of monoclonal antibodies SCC107/C5 that interacted specifically with serpin B3 but did not interact with serpin B4 was identified. Thus, it has been demonstrated that serpin B3 can be selectively determined in the presence of highly homologous serpin B4 using a biochip-based assay. PMID:26510597

  8. An abiotic analogue of the nuclear pore complex hydrogel.

    PubMed

    Bird, Sean P; Baker, Lane A

    2011-09-12

    We describe an abiotic hydrogel that mimics selectivity of the nuclear pore complex. Copolymerization of peptide tetramers (phenylalanine-serine-phenylalanine-glycine, FSFG) with acrylamide results in hydrophobic interactions significant enough to allow the formation of freestanding hydrogel structures. Incorporation of FSFG motifs also renders the hydrogels selective. Selective binding of importins and nuclear transport receptor-cargo complexes is qualitatively demonstrated and compared with polyacrylamide, hydrogels prepared from a control peptide, and hydrogels prepared from the nuclear pore complex protein Nsp1. These abiotic hydrogels will enable further studies of the unique transport mechanisms of the nuclear pore complex and provide an interesting paradigm for the future development of synthetic platforms for separations and selective interfaces.

  9. The synthesis and study of telechelic polyelectrolytes for hydrogel formation

    NASA Astrophysics Data System (ADS)

    Hunt, Jasmine N.

    Polymeric hydrogels comprised of oppositely charged ABA triblock copolymer polyelectrolytes based upon poly(allyl glycidyl ether-b-ethylene glycol-ballyl glycidyl ether), P(AGE-b-EG-b-AGE), with functionalized ionic 'A'-endblocks and a neutral, hydrophilic 'B'-block were synthesized. Aqueous solutions of poly-cations and -anions were mixed at room temperature, producing hydrogels through co-assembly driven by electrostatic interactions between the endblocks. Due the ease and modular nature of the synthesis and hydrogel formation, polymeric libraries differing in relative block lengths and ionic functionalization were created and the affects of polymer composition on the hydrogel's mechanical and structural properties were examined.

  10. Orientation in multi-layer chitosan hydrogel: morphology, mechanism, and design principle

    PubMed Central

    Nie, Jingyi; Lu, Wentao; Ma, Jianjun; Yang, Ling; Wang, Zhengke; Qin, An; Hu, Qiaoling

    2015-01-01

    Hydrogels with organized structure have attracted remarkable attentions for bio-related applications. Among the preparation of hierarchical hydrogel materials, fabrication of hydrogel with multi-layers is an important branch. Although the generation mechanism of layers had been fully discussed, sub-layer structure was not sufficiently studied. In this research, multi-layered chitosan hydrogel with oriented structure was constructed, and the formation mechanism of orientation was proposed, based on gelation behavior and entanglement of polymer chains in the hydrogel-solution system. Employing the layered-oriented characteristic, chitosan hydrogel materials with various shapes and structure can be designed and fabricated. PMID:25559867

  11. Bioinspired Smart Actuator Based on Graphene Oxide-Polymer Hybrid Hydrogels.

    PubMed

    Wang, Tao; Huang, Jiahe; Yang, Yiqing; Zhang, Enzhong; Sun, Weixiang; Tong, Zhen

    2015-10-28

    Rapid response and strong mechanical properties are desired for smart materials used in soft actuators. A bioinspired hybrid hydrogel actuator was designed and prepared by series combination of three trunks of tough polymer-clay hydrogels to accomplish the comprehensive actuation of "extension-grasp-retraction" like a fishing rod. The hydrogels with thermo-creep and thermo-shrinking features were successively irradiated by near-infrared (NIR) to execute extension and retraction, respectively. The GO in the hydrogels absorbed the NIR energy and transformed it into thermo-energy rapidly and effectively. The hydrogel with adhesion or magnetic force was adopted as the "hook" of the hybrid hydrogel actuator for grasping object. The hook of the hybrid hydrogel actuator was replaceable according to applications, even with functional materials other than hydrogels. This study provides an innovative concept to explore new soft actuators through combining response hydrogels and programming the same stimulus.

  12. Synthesis and characterization of antibacterial carboxymethyl cellulose/ZnO nanocomposite hydrogels.

    PubMed

    Yadollahi, Mehdi; Gholamali, Iman; Namazi, Hassan; Aghazadeh, Mohammad

    2015-03-01

    In this study, carboxymethyl cellulose/ZnO nanocomposite hydrogels have been synthesized through the in situ formation of ZnO nanoparticles within swollen carboxymethyl cellulose hydrogels. The formation of ZnO nanoparticles in the hydrogels was confirmed using X-ray diffraction, UV-vis spectroscopy and scanning electron microscopy (SEM) studies. SEM micrographs revealed the formation of ZnO nanoparticles with size range of 10-20 nm within the hydrogel matrix. The prepared nanocomposite hydrogels showed a pH and salt sensitive swelling behavior. The ZnO nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with neat hydrogel. The nanocomposite hydrogels demonstrated antibacterial effects against Escherichia coli and Staphylococcus aureus bacteria. The developed carboxymethyl cellulose/ZnO nanocomposite hydrogels can be used effectively for biomedical application.

  13. Finely dispersed single-walled carbon nanotubes for polysaccharide hydrogels.

    PubMed

    Yan, Liang Yu; Chen, Hailan; Li, Peng; Kim, Dong-Hwan; Chan-Park, Mary B

    2012-09-26

    Here we demonstrate a polysaccharide hydrogel reinforced with finely dispersed single-walled carbon nanotubes (SWNTs) using biocompatible dispersants O-carboxymethylchitosan (OC) and chondroitin sulfate A (CS-A) as a structural support. Both of the dispersants can disperse SWNTs in aqueous solutions and hydrogel matrix as individual tubes or small bundles. Additionally, we have found that compressive modulus and strain of the hydrogels reinforced with SWNTs were enhanced as much as two times by the addition of a few weight percent of SWNTs. Moreover, the SWNT-incorporated hydrogels exhibited lower impedance and higher charge capacity than the alginate/dispersant hydrogel without SWNTs. The OC and the CS-A demonstrated much higher reinforcing enhancement than a commercially available dispersant, sodium dodecyl sulfate. Combined with the experimental data on the mechanical and electrical properties, the biocompatibility of OC and CS-A can provide the possibility of biomedical application of the SWNT-reinforced hydrogels. PMID:22909447

  14. Preparation, characterization and magnetic behavior of a spin-labelled physical hydrogel containing a chiral cyclic nitroxide radical unit fixed inside the gelator molecule.

    PubMed

    Takemoto, Yusa; Yamamoto, Takayuki; Ikuma, Naohiko; Uchida, Yoshiaki; Suzuki, Katsuaki; Shimono, Satoshi; Takahashi, Hiroki; Sato, Nobuhiro; Oba, Yojiro; Inoue, Rintaro; Sugiyama, Masaaki; Tsue, Hirohito; Kato, Tatsuhisa; Yamauchi, Jun; Tamura, Rui

    2015-07-21

    An optically active amphiphilic nitroxide radical compound [(S,S,R)-], which contains a paramagnetic (2S,5S)-2,5-dimethyl-2,5-diphenylpyrrolidine-N-oxyl radical group fixed in the inner position together with a hydrophobic long alkyl chain and a hydrophilic (R)-alanine residue in the opposite terminal positions, was found to serve as a low-molecular-weight gelator in H2O to give rise to a spin-labelled physical hydrogel. Characterization of the hydrogel was performed by microscopic (SEM, TEM and AFM) techniques, XRD and SAXS measurements, and IR, UV and CD spectroscopies. The gel-sol transition temperature was determined by EPR spectral line-width (ΔHpp) analysis. Measurement of the temperature dependence of relative paramagnetic susceptibility (χrel) for the hydrogel and sol phases was achieved by means of the double-integration of VT-EPR spectra.

  15. Preparation and chromatographic evaluation of zwitterionic stationary phases with controllable ratio of positively and negatively charged groups.

    PubMed

    Cheng, Xiao-Dong; Hao, Yan-Hong; Peng, Xi-Tian; Yuan, Bi-Feng; Shi, Zhi-Guo; Feng, Yu-Qi

    2015-08-15

    The present study described the preparation and application of zwitterionic stationary phases (ACS) with controllable ratio of positively charged tertiary amine groups and negatively charged carboxyl groups. Various parameters, including water content, pH values and ionic strength of the mobile phase, were investigated to study the chromatographic characteristics of ACS columns. The prepared ACS columns demonstrated a mix-mode retention mechanism composed of surface adsorption, partitioning and electrostatic interactions. The elemental analysis of different batches of the ACS phases demonstrated good reproducibility of the preparation strategy. Additionally, various categories of compounds, including nucleosides, water-soluble vitamins, benzoic acid derivatives and basic compounds were successively employed to evaluate the separation selectivity of the prepared ACS stationary phases. These ACS phases exhibited entirely different selectivity and retention behavior from each other for various polar analytes, demonstrating the excellent application potential in the analysis of polar compounds in HILIC. PMID:25966373

  16. Heat resistance poly(vinyl alcohol) hydrogel

    NASA Astrophysics Data System (ADS)

    Yoshii, F.; Makuuchi, K.; Darwis, D.; Iriawan, T.; Razzak, M. T.; Rosiak, Janusz M.

    1995-08-01

    Six methods were used to evaluate the heat resistance of poly(vinyl alcohol) (PVA) hydrogel prepared by a combination of electron beam irradiation and acetalization of PVA. The physical properties of the hydrogel depended on the degree of acetilization which was affected by content of water in PVA sheet of acetalization in formaldehyde solution at 60°C. It was found that the optimum water content was 20-30%. The acetalized PVA sheet gave maximum tensile strength in electron beams irradiation at 100 kGy. The tensile strength of the hydrogel film increased to 20 MPa from 14 MPa by the irradiation. Heat resistance of the hydrogel was evaluated by measuring the mechanical properties after sterilization in a steam autoclave at 121°C for 90 min. The tensile strength decreased to 10 MPa whereas the elongation at break increased to 300%. The tackiness of the hydrogel was improved by radiation grafting of acrylic acid. Wholesomeness of the hydrogel as a wound dressing was evaluated by attaching to a burn or wound of the back skin of marmots. Advantages of the hydrogel over a gauze dressing were homogeneous adhesion to the affected parts, easy removal without damage to renewed skin and slightly faster rate of reconstruction of the injured skin.

  17. Synthesis of hydrogels based on poly(NIPAM) inserted into collagen sponge.

    PubMed

    Nistor, Manuela-Tatiana; Chiriac, Aurica P; Vasile, Cornelia; Verestiuc, Liliana; Nita, Loredana Elena

    2011-10-15

    The study presents the preparation of a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto the collagen porous membrane. The synthesis of the hydrogels was performed through radical copolymerization of N-isopropyl acrylamide (NIPAM) with diethylene glycol diacrylate (DEGDA) also as crosslinking agent, using ammonium persulfate as initiator and N,N,N',N'-tetramethylethylene diamine as activator, and it was achieved in the presence of the collagen matrix. The prepared hydrogels were characterized by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. The swelling behaviour of the semi-interpenetrated polymer network related on the hydrogel composition, it was also evaluated. The pore sizes of the synthesized hydrogels, much larger than the typical mesh size of a conventional hydrogel, allow to consider the hybrid hydrogel based on the inserted poly(NIPAM-co-DEGDA) onto collagen fibrils as a super-porous hydrogel. PMID:21700433

  18. Electron beam irradiation crosslinked hydrogels based on tyramine conjugated gum tragacanth.

    PubMed

    Tavakol, Moslem; Dehshiri, Saeedeh; Vasheghani-Farahani, Ebrahim

    2016-11-01

    In the present study, electron beam irradiation was applied to prepare a chemically crosslinked hydrogel based on tyramine conjugated gum tragacanth. Then, the gel content, swelling behavior and cytotoxicity of the hydrogels were evaluated. The gel content of the hydrogels was in the range of 75-85%. Equilibrium swelling degree of the hydrogels decreased from 51 to 14 with increasing polymer concentration and irradiation dose. Moisture retention capability of the hydrogels after 5h incubation at 37°C was in the range of 45-52 that is comparable with of commercial hydrogels. The cytotoxicity analysis showed the good biocompatibility of hydrogels. These results indicated that electron beam irradiation is a promising method to prepare chemically crosslinked tyramine conjugated gum tragacanth hydrogels for biomedical applications. Also, the versatility of electron beam irradiation for crosslinking of a variety of polymers possessing tyramine groups was demonstrated.

  19. Electron beam irradiation crosslinked hydrogels based on tyramine conjugated gum tragacanth.

    PubMed

    Tavakol, Moslem; Dehshiri, Saeedeh; Vasheghani-Farahani, Ebrahim

    2016-11-01

    In the present study, electron beam irradiation was applied to prepare a chemically crosslinked hydrogel based on tyramine conjugated gum tragacanth. Then, the gel content, swelling behavior and cytotoxicity of the hydrogels were evaluated. The gel content of the hydrogels was in the range of 75-85%. Equilibrium swelling degree of the hydrogels decreased from 51 to 14 with increasing polymer concentration and irradiation dose. Moisture retention capability of the hydrogels after 5h incubation at 37°C was in the range of 45-52 that is comparable with of commercial hydrogels. The cytotoxicity analysis showed the good biocompatibility of hydrogels. These results indicated that electron beam irradiation is a promising method to prepare chemically crosslinked tyramine conjugated gum tragacanth hydrogels for biomedical applications. Also, the versatility of electron beam irradiation for crosslinking of a variety of polymers possessing tyramine groups was demonstrated. PMID:27516298

  20. A mathematical model for electrical impedance spectroscopy of zwitterionic hydrogels.

    PubMed

    Feicht, Sarah E; Khair, Aditya S

    2016-08-17

    We report a mathematical model for ion transport and electrical impedance in zwitterionic hydrogels, which possess acidic and basic functional groups that carry a net charge at a pH not equal to the isoelectric point. Such hydrogels can act as an electro-mechanical interface between a relatively hard biosensor and soft tissue in the body. For this application, the electrical impedance of the hydrogel must be characterized to ensure that ion transport to the biosensor is not significantly hindered. The electrical impedance is the ratio of the applied voltage to the measured current. We consider a simple model system, wherein an oscillating voltage is applied across a hydrogel immersed in electrolyte and sandwiched between parallel, blocking electrodes. We employ the Poisson-Nernst-Planck (PNP) equations coupled with acid-base dissociation reactions for the charge on the hydrogel backbone to model the ionic transport across the hydrogel. The electrical impedance is calculated from the numerical solution to the PNP equations and subsequently analyzed via an equivalent circuit model to extract the hydrogel capacitance, resistance, and the capacitance of electrical double layers at the electrode-hydrogel interface. For example, we predict that an increase in pH from the isoelectric point, pH = 6.4 for a model PCBMA hydrogel, to pH = 8 reduces the resistance of the hydrogel by ∼40% and increases the double layer capacitance by ∼250% at an electrolyte concentration of 0.1 mM. The significant impact of charged hydrogel functional groups to the impedance is damped at higher electrolyte concentration.

  1. A mathematical model for electrical impedance spectroscopy of zwitterionic hydrogels.

    PubMed

    Feicht, Sarah E; Khair, Aditya S

    2016-08-17

    We report a mathematical model for ion transport and electrical impedance in zwitterionic hydrogels, which possess acidic and basic functional groups that carry a net charge at a pH not equal to the isoelectric point. Such hydrogels can act as an electro-mechanical interface between a relatively hard biosensor and soft tissue in the body. For this application, the electrical impedance of the hydrogel must be characterized to ensure that ion transport to the biosensor is not significantly hindered. The electrical impedance is the ratio of the applied voltage to the measured current. We consider a simple model system, wherein an oscillating voltage is applied across a hydrogel immersed in electrolyte and sandwiched between parallel, blocking electrodes. We employ the Poisson-Nernst-Planck (PNP) equations coupled with acid-base dissociation reactions for the charge on the hydrogel backbone to model the ionic transport across the hydrogel. The electrical impedance is calculated from the numerical solution to the PNP equations and subsequently analyzed via an equivalent circuit model to extract the hydrogel capacitance, resistance, and the capacitance of electrical double layers at the electrode-hydrogel interface. For example, we predict that an increase in pH from the isoelectric point, pH = 6.4 for a model PCBMA hydrogel, to pH = 8 reduces the resistance of the hydrogel by ∼40% and increases the double layer capacitance by ∼250% at an electrolyte concentration of 0.1 mM. The significant impact of charged hydrogel functional groups to the impedance is damped at higher electrolyte concentration. PMID:27464763

  2. Positively-charged reduced graphene oxide as an adhesion promoter for preparing a highly-stable silver nanowire film.

    PubMed

    Sun, Qijun; Lee, Seong Jun; Kang, Hyungseok; Gim, Yuseong; Park, Ho Seok; Cho, Jeong Ho

    2015-04-21

    An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3(+)) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3(+), spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3(+) ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion promoter are extremely stable under harsh conditions, including ultrasonication in a variety of solvents, 3M Scotch tape detachment test, mechanical bending up to 0.3% strain, or fatigue over 1000 cycles. The greatly enhanced adhesion force is attributed to the ionic interactions between the positively charged protonated amine groups in rGO-NH3(+) and the negatively charged hydroxo- and oxo-groups on the AgNWs. The positively charged GO-NH3(+) and commercial polycationic polymer (poly allylamine hydrochloride) are also prepared as adhesion promoters for comparison with rGO-NH3(+). Notably, the closely packed hexagonal atomic structure of rGO offers better barrier properties to water permeation and demonstrates promising utility in durable waterproof electronics. This work offers a simple method to prepare high-quality TCEs and is believed to have great potential application in flexible waterproof electronics. PMID:25807039

  3. Designing degradable hydrogels for orthogonal control of cell microenvironments

    PubMed Central

    Kharkar, Prathamesh M.

    2013-01-01

    Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness. However, thoughtful selection of hydrogel base materials, formation chemistries, and degradable moieties is necessary to achieve the appropriate level of property control and desired cellular response. In this review, hydrogel design considerations and materials for hydrogel preparation, ranging from natural polymers to synthetic polymers, are overviewed. Recent advances in chemical and physical methods to crosslink hydrogels are highlighted, as well as recent developments in controlling hydrogel degradation rates and modes of degradation. Special attention is given to spatial or temporal presentation of various biochemical and biophysical cues to modulate cell response in static (i.e., non-degradable) or dynamic (i.e., degradable) microenvironments. This review provides insight into the design of new cell-compatible, degradable hydrogels to understand and modulate cellular processes for various biomedical applications. PMID:23609001

  4. Controlled Thermoresponsive Hydrogels by Stereocomplexed PLA-PEG-PLA Prepared via Hybrid Micelles of Pre-Mixed Copolymers with Different PEG Lengths

    SciTech Connect

    Abebe, Daniel G.; Fujiwara, Tomoko

    2012-09-05

    The stereocomplexed hydrogels derived from the micelle mixture of two enantiomeric triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA, reported in 2001 exhibited sol-to-gel transition at approximately body temperature upon heating. However, the showed poor storage modulus (ca. 1000 Pa) determined their insufficiency as injectable implant biomaterials for many applications. In this study, the mechanical property of these hydrogels was significantly improved by the modifications of molecular weights and micelle structure. Co-micelles composed of block copolymers with two sizes of PEG block length were shown to possess unique and dissimilar properties from the micelles composed of single-sized block copolymers. The stereomixture of PLA-PEG-PLA comicelles showed a controllable sol-to-gel transition at a wide temperature range of 4 and 80 C. The sol-gel phase diagram displays a linear relationship of temperature versus copolymer composition; hence, a transition at body temperature can be readily achieved by adjusting the mixed copolymer ratio. The resulting thermoresponsive hydrogels exhibit a storage modulus notably higher (ca. 6000 Pa) than that of previously reported hydrogels. As a physical network solely governed by self-reorganization of micelles, followed by stereocomplexation, this unique system offers practical, safe, and simple implantable biomaterials.

  5. Controlled thermoresponsive hydrogels by stereocomplexed PLA-PEG-PLA prepared via hybrid micelles of pre-mixed copolymers with different PEG lengths.

    PubMed

    Abebe, Daniel G; Fujiwara, Tomoko

    2012-06-11

    The stereocomplexed hydrogels derived from the micelle mixture of two enantiomeric triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA, reported in 2001 exhibited sol-to-gel transition at approximately body temperature upon heating. However, the showed poor storage modulus (ca. 1000 Pa) determined their insufficiency as injectable implant biomaterials for many applications. In this study, the mechanical property of these hydrogels was significantly improved by the modifications of molecular weights and micelle structure. Co-micelles composed of block copolymers with two sizes of PEG block length were shown to possess unique and dissimilar properties from the micelles composed of single-sized block copolymers. The stereomixture of PLA-PEG-PLA comicelles showed a controllable sol-to-gel transition at a wide temperature range of 4 and 80 °C. The sol-gel phase diagram displays a linear relationship of temperature versus copolymer composition; hence, a transition at body temperature can be readily achieved by adjusting the mixed copolymer ratio. The resulting thermoresponsive hydrogels exhibit a storage modulus notably higher (ca. 6000 Pa) than that of previously reported hydrogels. As a physical network solely governed by self-reorganization of micelles, followed by stereocomplexation, this unique system offers practical, safe, and simple implantable biomaterials. PMID:22537225

  6. An injectable hyaluronic acid-tyramine hydrogel system for protein delivery.

    PubMed

    Lee, Fan; Chung, Joo Eun; Kurisawa, Motoichi

    2009-03-19

    Previously, we reported the independent tuning of mechanical strength (crosslinking density) and gelation rate of an injectable hydrogel system composed of hyaluronic acid-tyramine (HA-Tyr) conjugates. The hydrogels were formed through the oxidative coupling of tyramines which was catalyzed by hydrogen peroxide (H(2)O(2)) and horseradish peroxidase (HRP). Herein, we studied the encapsulation and release of model proteins using the HA-Tyr hydrogel. It was shown that the rapid gelation achieved by an optimal concentration of HRP could effectively encapsulate the proteins within the hydrogel network and thus prevented the undesired leakage of proteins into the surrounding tissues after injection. Hydrogels with different mechanical strengths were formed by changing the concentration of H(2)O(2) while maintaining the rapid gelation rate. The mechanical strength of the hydrogel controlled the release rate of proteins: stiff hydrogels released proteins slower compared to weak hydrogels. In phosphate buffer saline, alpha-amylase (negatively charged) was released sustainably from the hydrogel. Conversely, the release of lysozyme (positively charged) discontinued after the fourth hour due to electrostatic interactions with HA. In the presence of hyaluronidase, lysozymes were released continuously and completely from the hydrogel due to degradation of the hydrogel network. The activities of the released proteins were mostly retained which suggested that the HA-Tyr hydrogel is a suitable injectable and biodegradable system for the delivery of therapeutic proteins. PMID:19121348

  7. The synthesis of hydrogels with controlled distribution of polymer brushes in hydrogel network

    NASA Astrophysics Data System (ADS)

    Sun, YuWei; Zhou, Chao; Zhang, AoKai; Xu, LiQun; Yao, Fang; Cen, Lian; Fu, Guo-Dong

    2014-11-01

    Poly(ethylene glycol) (PEG) hydrogels with 3-dimensionally controlled well-defined poly(N-isopropylacrylamide) (poly(NIPAAm)) brushes were prepared by combined copper(I)-catalyzed azide-alkyne cycloaddition ("Click Chemistry") and atom transfer radical polymerization (ATRP). The resulting hydrogels were presented as representatives with their detailed synthesis routes and characterization. HPEG-S-poly(NIPAAm) is a hydrogel with poly(NIPAAm) brushes mainly grafted on surface, whereas HPEG-G-poly(NIPAAm) has a gradiently decreased poly(NIPAAm) brushes in their chain length from surface to inside. On the other hand, poly(NIPAAm) brushes in HPEG-U-poly(NIPAAm) are uniformly dispersed throughout the whole hydrogel network. Successful preparation of HPEG-S-poly(NIPAAm), HPEG-G-poly(NIPAAm) and HPEG-U-poly(NIPAAm) were ascertained by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Optical properties and thermal behaviors of these hydrogels were evaluated by UV-visible transmittance spectra and differential scanning calorimetry (DSC). Hence, the flexibility and controllability of the synthetic strategy in varying the distribution of polymer brushes and hydrogel properties was demonstrated. Hydrogels with tunable and well-defined 3-dimensional poly(NIPAAm) polymer brushes could be tailor-designed to find potential applications in smart devices or skin dressing, such as for diabetics as they have special optical and thermal behaviors.

  8. Hydrogel microspheres from biodegradable polymers as drug delivery systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of hydrogel microspheres were prepared from pectin, a hydrophilic biopolymer, and zein, a hydrophobic biopolymer, at varying weight ratios. The hydrogel formulation was conducted in the presence of calcium or other divalent metal ions at room temperature under mild conditions. Studies of ...

  9. Polyvinyl alcohol hydrogels for iontohporesis

    NASA Astrophysics Data System (ADS)

    Bera, Prasanta; Alam, Asif Ali; Arora, Neha; Tibarewala, Dewaki Nandan; Basak, Piyali

    2013-06-01

    Transdermal therapeutic systems propound controlled release of active ingredients through the skin into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. The iontophoresis deal with the systemic delivery of the bioactive agents (drug) by applying an electric current. It is basically an injection without the needle. The iontophoretic system requires a gel-based matrix to accommodate the bioactive agent. Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. In this work we have prepared polyvinyl alcohol (PVA) hydrogel. We have cross linked polyvinyl alcohol chemically with Glutaraldehyde with different wt%. FTIR study reveals the chemical changes during cross linking. Swelling in water, is done to have an idea about drug loading and drug release from the membrane. After drug loading to the hydrogels, we have studied the drug release property of the hydrogels using salicylic acid as a model drug.

  10. Characterization of low-molecular-weight hyaluronic acid-based hydrogel and differential stem cell responses in the hydrogel microenvironments.

    PubMed

    Kim, Jungju; Park, Yongdoo; Tae, Giyoong; Lee, Kyu Back; Hwang, Chang Mo; Hwang, Soon Jung; Kim, In Sook; Noh, Insup; Sun, Kyung

    2009-03-15

    Hyaluronic acid is a natural glycosaminoglycan involved in biological processes. Low-molecular-weight hyaluronic acid (10 and 50 kDa)-based hydrogel was synthesized using derivatized hyaluronic acid. Hyaluronic acid was acrylated by two steps: (1) introduction of an amine group using adipic acid dihydrazide, and (2) acrylation by N-acryloxysuccinimide. Injectable hyaluronic acid-based hydrogel was prepared by using acrylated hyaluronic acid and poly(ethylene glycol) tetra-thiols via Michael-type addition reaction. Mechanical properties of the hydrogel were evaluated by varying the molecular weight of acrylated hyaluronic acid (10 and 50 kDa) and the weight percent of hydrogel. Hydrogel based on 50-kDa hyaluronic acid showed the shortest gelation time and the highest complex modulus. Next, human mesenchymal stem cells were cultured in cell-adhesive RGD peptide-immobilized hydrogels together with bone morphogenic protein-2 (BMP-2). Cells cultured in the RGD/BMP-2-incorporated hydrogels showed proliferation rates higher than that of control or RGD-immobilized hydrogels. Real-time RT-PCR showed that the expression of osteoblast marker genes such as CBFalpha1 and alkaline phosphatase was increased in hyaluronic acid-based hydrogel, and the expression level was dependent on the molecular weight of hyaluronic acid, RGD peptide, and BMP-2. This study indicates that low-molecular-weight hyaluronic acid-based hydrogel can be applied to tissue regeneration as differentiation guidance materials of stem cells. PMID:18384163

  11. Ultrasound stimulated release of mimosa medicine from cellulose hydrogel matrix.

    PubMed

    Jiang, Huixin; Tovar-Carrillo, Karla; Kobayashi, Takaomi

    2016-09-01

    Ultrasound (US) drug release system using cellulose based hydrogel films was developed as triggered to mimosa. Here, the mimosa, a fascinating drug to cure injured skin, was employed as the loading drug in cellulose hydrogel films prepared with phase inversion method. The mimosa hydrogels were fabricated from dimethylacetamide (DMAc)/LiCl solution in the presence of mimosa, when the solution was exposed to ethanol vapor. The US triggered release of the mimosa from the hydrogel matrix was carried out under following conditions of US powers (0-30W) and frequencies (23, 43 and 96kHz) for different mimosa hydrogel matrix from 0.5wt% to 2wt% cellulose solution. To release the drug by US trigger from the matrix, the better medicine release was observed in the matrix prepared from the 0.5wt% cellulose solution when the 43kHz US was exposed to the aqueous solution with the hydrogel matrix. The release efficiency increased with the increase of the US power from 5 to 30W at 43kHz. Viscoelasticity of the hydrogel matrix showed that the hydrogel became somewhat rigid after the US exposure. FT-IR analysis of the mimosa hydrogel matrixes showed that during the US exposure, hydrogen bonds in the structure of mimosa-water and mimosa-cellulose were broken. This suggested that the enhancement of the mimosa release was caused by the US exposure.

  12. Thermoresponsive Nanocomposite Hydrogels: Transparency, Rapid Deswelling and Cell Release

    PubMed Central

    Hou, Yaping; Fei, Ruochong; Burkes, Jonathan C.; Lee, Shin Duk; Munoz-Pinto, Dany; Hahn, Mariah S.; Grunlan, Melissa A.

    2013-01-01

    Thermal modulation reversibly switches poly(N-isopropylacrylamide) (PNIPAAm) hydrogels between a water-swollen and a deswollen state which is useful for a variety of biomedical applications. The utility and efficiency of PNIPAAm hydrogels requires tailoring their rate of deswelling/reswelling, mechanical properties and/or optical clarity. In the current work, we prepared novel thermoresponsive nanocomposite hydrogels comprised of a PNIPAAm hydrogel matrix and polysiloxane colloidal nanoparticles (~54 nm ave. diameter) via in situ photopolymerization of aqueous solutions of NIPAAm monomer, N,N′-methylenebisacrylamide (BIS, crosslinker), photoinitiator and 0.5–4.0 wt% polysiloxane nanoparticles (wt% solids of nanoparticles with respect to NIPAAm weight) at ~7 °C. At these nanoparticle concentrations, the nanocomposite hydrogels were more optically transparent versus those prepared with analogous larger nanoparticles (~219 nm ave. diameter). The volume phase transition temperature (VPTT) of the nanocomposite hydrogels was conveniently unaltered versus that of the pure PNIPAAm hydrogel. Incorporation of nanoparticles caused enhancement in modulus as well as the extent and rate of deswelling. When cooled from 37 °C to 25 °C, mouse smooth muscle precursor cells (10T1/2) were effectively detached from nanocomposite hydrogel surfaces due to hydrogel swelling. PMID:24377059

  13. Environmentally Responsive Hydrogels

    NASA Astrophysics Data System (ADS)

    Schueneman, Susan M.; Chen, Wei

    2002-07-01

    A hydrogel experimental module was designed for an undergraduate upper-level laboratory course. Cross-linked poly(N-isopropylacrylamide) (PIPAM) is a thermo-sensitive hydrogel; it undergoes a volume collapse driven by hydrophobic interactions in pure water as the temperature increases to 32 °C. The extent and temperature of the volume transition are two critical parameters in its applications ranging from pharmaceutics to biotechnology and they can be controlled by incorporating ionic components in the PIPAM system. In this experiment, linear PIPAM, cross-linked neutral PIPAM gel, and cross-linked ionic PIPAM gel were prepared by radical polymerization. Viscosity, molecular weight, and thermal transition (cloud point) of linear PIPAM were determined. Volume collapses of the neutral and ionic PIPAM gels as a function of temperature were examined and compared. In this module, students were exposed to original literature and contemporary chemical research in polymer chemistry and they learned to integrate concepts from different disciplines of chemistry into a unified experimental approach to problem solving. This module could also be used for polymer chemistry or physical chemistry laboratory courses.

  14. Molecular structure of self-healing polyampholyte hydrogels analyzed from tensile behaviors.

    PubMed

    Sun, Tao Lin; Luo, Feng; Kurokawa, Takayuki; Karobi, Sadia Nazneen; Nakajima, Tasuku; Gong, Jian Ping

    2015-12-28

    Recently, charge balanced polyampholytes (PA) have been found to form tough and self-healing hydrogels. This class of physical hydrogels have a very high equilibrated polymer concentration in water (ca. 40-50 wt%), and are strongly viscoelastic. They are synthesized by random copolymerization of equal amounts of oppositely charged monomers at a high concentration, followed by a dialysis process of the small counter-ions and co-ions in water. The randomly distributed, opposite charges of the polymer form multiple ionic bonds of intra- and inter-chains with strength distribution. The strong inter-chain bonds, stabilized by topological entanglement, serve as quasi-permanent crosslinks, imparting the elasticity, while the weak bonds, both inter- and intra-chains, reversibly break and re-form to dissipate energy to toughen the materials. In this work, we intend to clarify the structure of the physical PA hydrogels from the tensile behaviors of the PA hydrogels. To clarify the structure and its formation mechanism, we analysed the tensile behaviors of the samples before and after the dialysis. We separated the quasi-permanent crosslinking of strong inter-chain bonds and the dynamic crosslinking of weak inter-chain bonds by using a combined model that consists of the Upper Convected Maxwell model and the Gent strain hardening model. The model fitting of the tensile behaviors extracts quantitative structural parameters, including the densities of weak and strong inter-chain bonds and the theoretical finite extensibility of polymer chains. Based on the fitting results of the combined model, the structural parameters of partial chains at a fixed observation time, including the Kuhn number, Kuhn length, and chain conformation, are determined using the scaling theory. The effects of monomer concentration at preparation, the effect of dialysis and the initial strain rate on the dynamic structure of PA gels, are discussed based on these analyses.

  15. Processing Techniques and Applications of Silk Hydrogels in Bioengineering.

    PubMed

    Floren, Michael; Migliaresi, Claudio; Motta, Antonella

    2016-01-01

    Hydrogels are an attractive class of tunable material platforms that, combined with their structural and functional likeness to biological environments, have a diversity of applications in bioengineering. Several polymers, natural and synthetic, can be used, the material selection being based on the required functional characteristics of the prepared hydrogels. Silk fibroin (SF) is an attractive natural polymer for its excellent processability, biocompatibility, controlled degradation, mechanical properties and tunable formats and a good candidate for the fabrication of hydrogels. Tremendous effort has been made to control the structural and functional characteristic of silk hydrogels, integrating novel biological features with advanced processing techniques, to develop the next generation of functional SF hydrogels. Here, we review the several processing methods developed to prepare advanced SF hydrogel formats, emphasizing a bottom-up approach beginning with critical structural characteristics of silk proteins and their behavior under specific gelation environments. Additionally, the preparation of SF hydrogel blends and other advanced formats will also be discussed. We conclude with a brief description of the attractive utility of SF hydrogels in relevant bioengineering applications. PMID:27649251

  16. Processing Techniques and Applications of Silk Hydrogels in Bioengineering

    PubMed Central

    Floren, Michael; Migliaresi, Claudio; Motta, Antonella

    2016-01-01

    Hydrogels are an attractive class of tunable material platforms that, combined with their structural and functional likeness to biological environments, have a diversity of applications in bioengineering. Several polymers, natural and synthetic, can be used, the material selection being based on the required functional characteristics of the prepared hydrogels. Silk fibroin (SF) is an attractive natural polymer for its excellent processability, biocompatibility, controlled degradation, mechanical properties and tunable formats and a good candidate for the fabrication of hydrogels. Tremendous effort has been made to control the structural and functional characteristic of silk hydrogels, integrating novel biological features with advanced processing techniques, to develop the next generation of functional SF hydrogels. Here, we review the several processing methods developed to prepare advanced SF hydrogel formats, emphasizing a bottom-up approach beginning with critical structural characteristics of silk proteins and their behavior under specific gelation environments. Additionally, the preparation of SF hydrogel blends and other advanced formats will also be discussed. We conclude with a brief description of the attractive utility of SF hydrogels in relevant bioengineering applications. PMID:27649251

  17. Preparation, assessment, and comparison of α-chitin nano-fiber films with different surface charges

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Jiang, Jie; Liu, Liang; Zheng, Ke; Yu, Shiyuan; Fan, Yimin

    2015-05-01

    Chitin nano-fibers with positive and negative charges have been, respectively, produced from partially deacetylated and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidized α-chitin. The average diameters and lengths of the TEMPO-oxidized chitin nano-fibers (TOChN) were 14 ± 4.3 and 190 ± 140 nm, respectively, and the average diameters and lengths of the partially deacetylated chitin nano-fibers (DEChN) were 6 ± 1.7 and 320 ± 105 nm, respectively. A partially deacetylated chitin nano-fiber film (DEChN-F), a TEMPO-mediated and oxidized chitin nano-fiber film (TOChN-F), and a composite film (DE-TO-ChN-F) consisting of a combination of the two were prepared by drying the dispersions at 40 °C. The DEChN-F, TOChN-F, and DE-TO-ChN-F all have similar tensile strengths of approximately 90 MPa; however, the chitosan film (Chitosan-F) had a tensile strength of approximately 30 MPa. In addition, TOChN-F and DE-TO-ChN-F have a thermal weight loss at 210 °C, and DEChN-F has a thermal weight loss at 280 °C. DEChN-F was found to have antimicrobial activity with regards to Escherichia coli. Finally, the chitin nano-fiber films could be slightly degraded by cellulase, which provided a novel biological performance of the chitin nano-material.

  18. Preparation, assessment, and comparison of α-chitin nano-fiber films with different surface charges.

    PubMed

    Zhang, Yan; Jiang, Jie; Liu, Liang; Zheng, Ke; Yu, Shiyuan; Fan, Yimin

    2015-01-01

    Chitin nano-fibers with positive and negative charges have been, respectively, produced from partially deacetylated and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidized α-chitin. The average diameters and lengths of the TEMPO-oxidized chitin nano-fibers (TOChN) were 14 ± 4.3 and 190 ± 140 nm, respectively, and the average diameters and lengths of the partially deacetylated chitin nano-fibers (DEChN) were 6 ± 1.7 and 320 ± 105 nm, respectively. A partially deacetylated chitin nano-fiber film (DEChN-F), a TEMPO-mediated and oxidized chitin nano-fiber film (TOChN-F), and a composite film (DE-TO-ChN-F) consisting of a combination of the two were prepared by drying the dispersions at 40 °C. The DEChN-F, TOChN-F, and DE-TO-ChN-F all have similar tensile strengths of approximately 90 MPa; however, the chitosan film (Chitosan-F) had a tensile strength of approximately 30 MPa. In addition, TOChN-F and DE-TO-ChN-F have a thermal weight loss at 210 °C, and DEChN-F has a thermal weight loss at 280 °C. DEChN-F was found to have antimicrobial activity with regards to Escherichia coli. Finally, the chitin nano-fiber films could be slightly degraded by cellulase, which provided a novel biological performance of the chitin nano-material.

  19. Photothermally driven fast responding photo-actuators fabricated with comb-type hydrogels and magnetite nanoparticles

    PubMed Central

    Lee, Eunsu; Kim, Dowan; Kim, Haneul; Yoon, Jinhwan

    2015-01-01

    To overcome the slow kinetics of the volume phase transition of stimuli-responsive hydrogels as platforms for soft actuators, thermally responsive comb-type hydrogels were prepared using synthesized poly(N-isopropylacrylamide) macromonomers bearing graft chains. Fast responding light-responsive hydrogels were fabricated by combining a comb-type hydrogel matrix with photothermal magnetite nanoparticles (MNP). The MNPs dispersed in the matrix provide heat to stimulate the volume change of the hydrogel matrix by converting absorbed visible light to thermal energy. In this process, the comb-type hydrogel matrix exhibited a rapid response due to the free, mobile grafted chains. The comb-type hydrogel exhibited significantly enhanced light-induced volume shrinkage and rapid recovery. The comb-type hydrogels containing MNP were successfully used to fabricate a bilayer-type photo-actuator with fast bending motion. PMID:26459918

  20. Preparation of porous bioceramics using reverse thermo-responsive hydrogels in combination with rhBMP-2 carriers: in vitro and in vivo evaluation.

    PubMed

    Fu, Yin-Chih; Chen, Chung-Hwan; Wang, Chau-Zen; Wang, Yan-Hsiung; Chang, Je-Ken; Wang, Gwo-Jaw; Ho, Mei-Ling; Wang, Chih-Kuang

    2013-11-01

    Porous biphasic calcium phosphates (BCP) were fabricated using reverse thermo-responsive hydrogels with hydroxyapatite (HAp) and β-tricalcium (β-TCP) powder and planetary centrifugal mixer. This hydrogel mixture slurry will shrink and compress the HAp powder during the sintering process. The porous bioceramics are expected to have good mechanical properties after sintering at 1200°C. Reverse thermo-responsive hydrogels of poly[(N-isopropylacrylamide)-co-(methacrylic acid)] p(NiPAAm-MAA) were synthesized by free-radical cross-linking copolymerization, and their chemical properties were evaluated by nuclear magnetic resonance spectroscopy, infrared spectroscopy, and electrospray-ionization mass spectrometry. The lower critical solution temperature (LCST) of the hydrogel was determined using turbidity measurements. A thermogravimetric analysis was used to examine the thermal properties. The porous bioceramic properties were analyzed by X-ray diffraction, scanning electron microscopy, bulk density, compressive strength testing and cytotoxicity. The compressive strength and average porosity of the porous bioceramics were examined at approximately 6.8MPa and 66% under 10wt% p(NiPAAm-MAA)=99:1 condition. The ratio of HAp/β-TCP can adjust two different compositional behaviors during the 1200°C sintering process without resulting in cell toxicity. The (rhBMP-2)-HAp-PLGA carriers were fabricated as in our previous study of the double emulsion and drop-coating technique. Results of animal study included histological micrographs of the 1-mm defect in the femurs, with the rhBMP-2 carrier group, the bioceramic spacer group and the bioceramic spacer with rhBMP-2 carriers group showing better callus formation around the femur defect site than the control group. The optimal dual effects of the bone growth factors from osteoconductive bioceramics and osteoinductive rhBMP-2 carriers produced better bone formation. PMID:23880039

  1. Positively-charged reduced graphene oxide as an adhesion promoter for preparing a highly-stable silver nanowire film

    NASA Astrophysics Data System (ADS)

    Sun, Qijun; Lee, Seong Jun; Kang, Hyungseok; Gim, Yuseong; Park, Ho Seok; Cho, Jeong Ho

    2015-04-01

    An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3+) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3+, spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3+ ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion promoter are extremely stable under harsh conditions, including ultrasonication in a variety of solvents, 3M Scotch tape detachment test, mechanical bending up to 0.3% strain, or fatigue over 1000 cycles. The greatly enhanced adhesion force is attributed to the ionic interactions between the positively charged protonated amine groups in rGO-NH3+ and the negatively charged hydroxo- and oxo-groups on the AgNWs. The positively charged GO-NH3+ and commercial polycationic polymer (poly allylamine hydrochloride) are also prepared as adhesion promoters for comparison with rGO-NH3+. Notably, the closely packed hexagonal atomic structure of rGO offers better barrier properties to water permeation and demonstrates promising utility in durable waterproof electronics. This work offers a simple method to prepare high-quality TCEs and is believed to have great potential application in flexible waterproof electronics.An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3+) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3+, spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3+ ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion

  2. Charge generation and morphology in P3HT : PCBM nanoparticles prepared by mini-emulsion and reprecipitation methods

    NASA Astrophysics Data System (ADS)

    Schwarz, Kyra N.; Farley, Sam B.; Smith, Trevor A.; Ghiggino, Kenneth P.

    2015-11-01

    Organic semiconductor nanoparticles provide a potentially scalable approach for photovoltaics that can be processed from aqueous media. Particles of poly(3-hexylthiophene) (P3HT) : phenyl-C61-butyric acid methyl ester (PCBM) were prepared using two techniques; those produced by a mini-emulsion method contained greater amounts of crystalline P3HT domains with charge generation resembling phase-separated annealed solvent-cast films.Organic semiconductor nanoparticles provide a potentially scalable approach for photovoltaics that can be processed from aqueous media. Particles of poly(3-hexylthiophene) (P3HT) : phenyl-C61-butyric acid methyl ester (PCBM) were prepared using two techniques; those produced by a mini-emulsion method contained greater amounts of crystalline P3HT domains with charge generation resembling phase-separated annealed solvent-cast films. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06244f

  3. Physically crosslinked-sacran hydrogel films for wound dressing application.

    PubMed

    Wathoni, Nasrul; Motoyama, Keiichi; Higashi, Taishi; Okajima, Maiko; Kaneko, Tatsuo; Arima, Hidetoshi

    2016-08-01

    The thin hydrogel films consisting of water-swollen polymer networks can potentially be applied for biomedical fields. Recently, natural polysaccharides have great attentions to be developed as wound healing and protection. In the present study, we newly prepared and characterized a physically crosslinked-hydrogel film composed of a novel megamolecular polysaccharide sacran for wound dressing application. We successfully fabricated a physically crosslinked-sacran hydrogel film by a solvent-casting method. The thickness of a sacran hydrogel film was lower than that of a sodium alginate (Na-alginate) film. Importantly, the swollen ratio of a sacran hydrogel film in water at 24h was 19-fold, compared to initial weight. Meanwhile, a Na-alginate hydrogel film was completely broken apart after rehydration. Moreover, a sacran hydrogel film did not show any cytotoxicity on NIH3T3 cells, a murine fibroblast cell line. The in vivo skin hydration study revealed that a sacran hydrogel film significantly increased the moisture content on hairless mice skin and considerably improved wound healing ability, compared to control (non-treated), probably due to not only the moisturing effect but also the anti-inflammatory effect of sacran. These results suggest that sacran has the potential properties as a basic biomaterial in a hydrogel film for wound dressing application. PMID:27151668

  4. New in situ crosslinking chemistries for hydrogelation

    NASA Astrophysics Data System (ADS)

    Roberts, Meredith Colleen

    Over the last half century, hydrogels have found immense value as biomaterials in a vast number of biomedical and pharmaceutical applications. One subset of hydrogels receiving increased attention is in situ forming gels. Gelling by either bioresponsive self-assembly or mixing of binary crosslinking systems, these technologies are useful in minimally invasive applications as well as drug delivery systems in which the sol-to-gel transition aids the formulation's performance. Thus far, the field of in situ crosslinking hydrogels has received limited attention in the development of new crosslinking chemistries. Moreover, not only does the chemical nature of the crosslinking moieties allow these systems to perform in situ, but they contribute dramatically to the mechanical properties of the hydrogel networks. For example, reversible crosslinks with finite lifetimes generate dynamic viscoelastic gels with time-dependent properties, whereas irreversible crosslinks form highly elastic networks. The aim of this dissertation is to explore two new covalent chemistries for their ability to crosslink hydrogels in situ under physiological conditions. First, reversible phenylboronate-salicylhydroxamate crosslinking was implemented in a binary, multivalent polymeric system. These gels formed rapidly and generated hydrogel networks with frequency-dependent dynamic rheological properties. Analysis of the composition-structure-property relationships of these hydrogels---specifically considering the effects of pH, degree of polymer functionality, charge of the polymer backbone and polymer concentration on dynamic theological properties---was performed. These gels demonstrate diverse mechanical properties, due to adjustments in the binding equilibrium of the pH-sensitive crosslinks, and thus have the potential to perform in a range of dynamic or bioresponsive applications. Second, irreversible catalyst-free "click" chemistry was employed in the hydrogelation of multivalent azide

  5. One-pot template-free synthesis of monodisperse hollow hydrogel microspheres and their resulting properties.

    PubMed

    Lim, Hyung-Seok; Kwon, Eunji; Lee, Moonjoo; Moo Lee, Young; Suh, Kyung-Do

    2013-08-01

    Monodisperse poly(methacrylic acid/ethyleneglycoldimethacrylate) (MAA/EGDMA) hollow microcapsules, which exhibit pH-responsive behavior, are prepared by diffusion of cationic surfactants and hydrophobic interaction. During the association of the negatively charged hydrogel microspheres and an oppositely charged surfactant (cetyltrimethylammonium bromide, CTA(+)B), the hydrophobic polymer-surfactant complexes that form are separated from the internal water; consequently, a hollow structure can be formed. Confocal laser scanning microscopy, UV spectro-scopy and zeta potential are employed to study the formation of the hollow structure during the diffusion of the cationic surfactant. The controlled release behavior of methylene blue as a model drug from the as-prepared poly(MAA/EGDMA) microcapsules with a hollow structure is investigated under different pH conditions. The hollow structure can be retained, even during repetitive pH changes.

  6. Patterning surface by site selective capture of biopolymer hydrogel beads.

    PubMed

    Guyomard-Lack, Aurélie; Moreau, Céline; Delorme, Nicolas; Marquis, Mélanie; Fang, Aiping; Bardeau, Jean-François; Cathala, Bernard

    2012-06-01

    This communication describes the fabrication of microstructured biopolymer surfaces by the site-selective capture of pectin hydrogel beads. A positively charged surface consisting of poly-L-lysine (PLL) was subjected to site-selective enzymatic degradation using patterned polydimethylsiloxane (PDMS) stamps covalently modified with trypsin, according to the recently described method. The patterned surface was used to capture ionically cross-linked pectin beads. The desired patterning of the hydrogel surfaces was generated by site-selective immobilization of these pectin beads. The ability of the hydrogels to be dried and swollen in water was assessed.

  7. Patterning surface by site selective capture of biopolymer hydrogel beads.

    PubMed

    Guyomard-Lack, Aurélie; Moreau, Céline; Delorme, Nicolas; Marquis, Mélanie; Fang, Aiping; Bardeau, Jean-François; Cathala, Bernard

    2012-06-01

    This communication describes the fabrication of microstructured biopolymer surfaces by the site-selective capture of pectin hydrogel beads. A positively charged surface consisting of poly-L-lysine (PLL) was subjected to site-selective enzymatic degradation using patterned polydimethylsiloxane (PDMS) stamps covalently modified with trypsin, according to the recently described method. The patterned surface was used to capture ionically cross-linked pectin beads. The desired patterning of the hydrogel surfaces was generated by site-selective immobilization of these pectin beads. The ability of the hydrogels to be dried and swollen in water was assessed. PMID:22326339

  8. Photonic hydrogel sensors.

    PubMed

    Yetisen, Ali K; Butt, Haider; Volpatti, Lisa R; Pavlichenko, Ida; Humar, Matjaž; Kwok, Sheldon J J; Koo, Heebeom; Kim, Ki Su; Naydenova, Izabela; Khademhosseini, Ali; Hahn, Sei Kwang; Yun, Seok Hyun

    2016-01-01

    Analyte-sensitive hydrogels that incorporate optical structures have emerged as sensing platforms for point-of-care diagnostics. The optical properties of the hydrogel sensors can be rationally designed and fabricated through self-assembly, microfabrication or laser writing. The advantages of photonic hydrogel sensors over conventional assay formats include label-free, quantitative, reusable, and continuous measurement capability that can be integrated with equipment-free text or image display. This Review explains the operation principles of photonic hydrogel sensors, presents syntheses of stimuli-responsive polymers, and provides an overview of qualitative and quantitative readout technologies. Applications in clinical samples are discussed, and potential future directions are identified. PMID:26485407

  9. Antifouling properties of hydrogels

    NASA Astrophysics Data System (ADS)

    Murosaki, Takayuki; Ahmed, Nafees; Gong, Jian Ping

    2011-12-01

    Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.

  10. Photonic hydrogel sensors.

    PubMed

    Yetisen, Ali K; Butt, Haider; Volpatti, Lisa R; Pavlichenko, Ida; Humar, Matjaž; Kwok, Sheldon J J; Koo, Heebeom; Kim, Ki Su; Naydenova, Izabela; Khademhosseini, Ali; Hahn, Sei Kwang; Yun, Seok Hyun

    2016-01-01

    Analyte-sensitive hydrogels that incorporate optical structures have emerged as sensing platforms for point-of-care diagnostics. The optical properties of the hydrogel sensors can be rationally designed and fabricated through self-assembly, microfabrication or laser writing. The advantages of photonic hydrogel sensors over conventional assay formats include label-free, quantitative, reusable, and continuous measurement capability that can be integrated with equipment-free text or image display. This Review explains the operation principles of photonic hydrogel sensors, presents syntheses of stimuli-responsive polymers, and provides an overview of qualitative and quantitative readout technologies. Applications in clinical samples are discussed, and potential future directions are identified.

  11. Amidated pectin based hydrogels: synthesis, characterization and cytocompatibility study.

    PubMed

    Mishra, R K; Singhal, J P; Datt, M; Banthia, A K

    2007-01-01

    The design and development of pectin-based hydrogels were attempted through the chemical modification of pectin with diethanolamine (DA). Diethanolamine modified pectin (DAMP) was synthesized by the chemical modification of pectin with varying concentrations of DA (1:1,1:2,1:3 and 1:4) at 5 oC in methanol. The modified product was used for the preparation of the hydrogel with glutaraldehyde (GA) reagent. The prepared hydrogels were characterized by Fourier transform infrared (FTIR) spectroscopy; organic elemental analysis, and X-ray diffraction (XRD), and swelling, hemocompatibility and cytocompatibility studies of the prepared hydrogels were also done. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. The XRD pattern of the DAMP hydrogel clearly indicated that there was a considerable increase in crystallinity as compared to parent pectin. The degree of amidation (DA) and molar and mass reaction yields (Ym and Yn) was calculated based on the results of organic elemental analysis. Drug release studies from the hydrogel membranes were also evaluated in a Franz's diffusion cell. The hydrogels demonstrated good water holding properties and were found to be compatible with B-16 melanoma cells and human blood.

  12. Chitosan Hydrogel in combination with Nerolidol for healing wounds.

    PubMed

    Ferreira, Maria Onaira Gonçalves; Leite, Layara Lorrana Ribeiro; de Lima, Idglan Sá; Barreto, Humberto Medeiros; Nunes, Lívio César Cunha; Ribeiro, Alessandra Braga; Osajima, Josy Anteveli; da Silva Filho, Edson Cavalcanti

    2016-11-01

    Chitosan is a natural polymer with antibacterial property, that is biodegradable, extremely abundant and non-toxic. This study aimed to develop and characterize chitosan hydrogels in combination with nerolidol, in order to optimize the antimicrobial and healing properties. The hydrogels were prepared using a reaction of the chitosan with acetic acid solution, followed by the addition of 2 or 4% of the nerolidol. Using thermogravimetry, differential scanning calorimetry and infrared spectroscopy, the incorporation of nerolidol in the hydrogel was confirmed. Direct contact tests using hydrogels and Staphylococcus aureus showed a synergistic effect in the materials, enabling total inhibition of bacterial growth. The hydrogel containing 2% nerolidol showed excellent healing effects. The beginning of re-epithelialization and reorganization of collagen was already observed on the 7th day of treatment. The material created proofed to be promising as a healing and antibacterial agent.

  13. Chondrogenesis in injectable enzymatically crosslinked heparin/dextran hydrogels.

    PubMed

    Jin, Rong; Moreira Teixeira, Liliana S; Dijkstra, Pieter J; van Blitterswijk, Clemens A; Karperien, Marcel; Feijen, Jan

    2011-05-30

    In this study, injectable hydrogels were prepared by horseradish peroxidase-mediated co-crosslinking of dextran-tyramine (Dex-TA) and heparin-tyramine (Hep-TA) conjugates and used as scaffolds for cartilage tissue engineering. The swelling and mechanical properties of these hydrogels can be easily controlled by the Dex-TA/Hep-TA weight ratio. When chondrocytes were incorporated in these gels, cell viability and proliferation were highest for gels with a 50/50 weight ratio of Dex-TA/Hep-TA. Moreover, these hydrogels induced an enhanced production of chondroitin sulfate and a more abundant presence of collagen as compared to Dex-TA hydrogels. The results indicate that injectable Dex-TA/Hep-TA hydrogels are promising scaffolds for cartilage regeneration. PMID:21291927

  14. Chitosan Hydrogel in combination with Nerolidol for healing wounds.

    PubMed

    Ferreira, Maria Onaira Gonçalves; Leite, Layara Lorrana Ribeiro; de Lima, Idglan Sá; Barreto, Humberto Medeiros; Nunes, Lívio César Cunha; Ribeiro, Alessandra Braga; Osajima, Josy Anteveli; da Silva Filho, Edson Cavalcanti

    2016-11-01

    Chitosan is a natural polymer with antibacterial property, that is biodegradable, extremely abundant and non-toxic. This study aimed to develop and characterize chitosan hydrogels in combination with nerolidol, in order to optimize the antimicrobial and healing properties. The hydrogels were prepared using a reaction of the chitosan with acetic acid solution, followed by the addition of 2 or 4% of the nerolidol. Using thermogravimetry, differential scanning calorimetry and infrared spectroscopy, the incorporation of nerolidol in the hydrogel was confirmed. Direct contact tests using hydrogels and Staphylococcus aureus showed a synergistic effect in the materials, enabling total inhibition of bacterial growth. The hydrogel containing 2% nerolidol showed excellent healing effects. The beginning of re-epithelialization and reorganization of collagen was already observed on the 7th day of treatment. The material created proofed to be promising as a healing and antibacterial agent. PMID:27516288

  15. A highly sensitive and stable glucose biosensor using thymine-based polycations into laponite hydrogel films.

    PubMed

    Paz Zanini, Veronica I; Gavilán, Maximiliano; López de Mishima, Beatriz A; Martino, Débora M; Borsarelli, Claudio D

    2016-04-01

    A series of glucose bioelectrodes were prepared by glucose oxidase (GOx) immobilization into laponite hydrogel films containing DNA bioinspired polycations made of vinylbenzyl thymine (VBT) and vinylbenzyl triethylammonium chloride (VBA) with general formulae (VBT)m(VBA)n](n+)≈25 with m=0, 1 and n=2, 4, 8, deposited onto glassy carbon electrode. The bioelectrodes were characterized by chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy. Results indicated that the electrochemical properties of the laponite hydrogel films were largely improved by the incorporation of thymine-based polycations, being proportional to the positive charge density of the polycation molecule. After incorporation of glucose oxidase, the sensitivity of the bioelectrode to glucose increased with the positive charge density of the polycation. Additionally, the presence of the vinylbenzyl thymine moiety played a role in the long-term stability and reproducibility of the bioelectrode signal. As a consequence, the [(VBT)(VBA)8](8+)≈25 was the most appropriate polycation for bioelectrode preparation and glucose sensing, with a specific sensitivity of se=176 mA mmol(-1)Lcm(-2)U(-1), almost two-order of magnitude larger than other laponite immobilized GOx bioelectrodes reported elsewhere. These features were confirmed by testing the bioelectrode for a selective determination of glucose in powder milk and blood serum samples without interference of either ascorbic or uric acids under the experimental conditions. The present study demonstrates the suitability of DNA bioinspired water-soluble polycations [(VBT)m(VBA)n](n+)≈25 for enzyme immobilization like GOx into laponite hydrogels, and the preparation of highly sensitive and stable bioelectrodes on glassy carbon surface. PMID:26838454

  16. Hydrogel Actuation by Electric Field Driven Effects

    NASA Astrophysics Data System (ADS)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  17. Enzymatic regulation of functional vascular networks using gelatin hydrogels.

    PubMed

    Chuang, Chia-Hui; Lin, Ruei-Zeng; Tien, Han-Wen; Chu, Ya-Chun; Li, Yen-Cheng; Melero-Martin, Juan M; Chen, Ying-Chieh

    2015-06-01

    To manufacture tissue engineering-based functional tissues, scaffold materials that can be sufficiently vascularized to mimic the functionality and complexity of native tissues are needed. Currently, vascular network bioengineering is largely carried out using natural hydrogels as embedding scaffolds, but most natural hydrogels have poor mechanical stability and durability, factors that critically limit their widespread use. In this study, we examined the suitability of gelatin-phenolic hydroxyl (gelatin-Ph) hydrogels that can be enzymatically crosslinked, allowing tuning of the storage modulus and the proteolytic degradation rate, for use as injectable hydrogels to support the human progenitor cell-based formation of a stable and mature vascular network. Porcine gelatin-Ph hydrogels were found to be cytocompatible with human blood-derived endothelial colony-forming cells and white adipose tissue-derived mesenchymal stem cells, resulting in >87% viability, and cell proliferation and spreading could be modulated by using hydrogels with different proteolytic degradability and stiffness. In addition, gelatin was extracted from mouse dermis and murine gelatin-Ph hydrogels were prepared. Importantly, implantation of human cell-laden porcine or murine gelatin-Ph hydrogels into immunodeficient mice resulted in the rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, the degree of enzymatic crosslinking of the gelatin-Ph hydrogels could be used to modulate cell behavior and the extent of vascular network formation in vivo. Our report details a technique for the synthesis of gelatin-Ph hydrogels from allogeneic or xenogeneic dermal skin and suggests that these hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.

  18. Enzymatic regulation of functional vascular networks using gelatin hydrogels

    PubMed Central

    Chuang, Chia-Hui; Lin, Ruei-Zeng; Tien, Han-Wen; Chu, Ya-Chun; Li, Yen-Cheng; Melero-Martin, Juan M.; Chen, Ying-Chieh

    2015-01-01

    To manufacture tissue engineering-based functional tissues, scaffold materials that can be sufficiently vascularized to mimic the functionality and complexity of native tissues are needed. Currently, vascular network bioengineering is largely carried out using natural hydrogels as embedding scaffolds, but most natural hydrogels have poor mechanical stability and durability, factors that critically limit their widespread use. In this study, we examined the suitability of gelatin-phenolic hydroxyl (gelatin-Ph) hydrogels that can be enzymatically crosslinked, allowing tuning of the storage modulus and the proteolytic degradation rate, for use as injectable hydrogels to support the human progenitor cell-based formation of a stable and mature vascular network. Porcine gelatin-Ph hydrogels were found to be cytocompatible with human blood-derived endothelial colony-forming cells and white adipose tissue-derived mesenchymal stem cells, resulting in >87% viability, and cell proliferation and spreading could be modulated by using hydrogels with different proteolytic degradability and stiffness. In addition, gelatin was extracted from mouse dermis and murine gelatin-Ph hydrogels were prepared. Importantly, implantation of human cell-laden porcine or murine gelatin-Ph hydrogels into immunodeficient mice resulted in the rapid formation of functional anastomoses between the bioengineered human vascular network and the mouse vasculature. Furthermore, the degree of enzymatic crosslinking of the gelatin-Ph hydrogels could be used to modulate cell behavior and the extent of vascular network formation in vivo. Our report details a technique for the synthesis of gelatin-Ph hydrogels from allogeneic or xenogeneic dermal skin and suggests that these hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues. PMID:25749296

  19. Hydrogels derived from demineralized and decellularized bone extracellular matrix

    PubMed Central

    Sawkins, M.J.; Bowen, W.; Dhadda, P.; Markides, H.; Sidney, L.E.; Taylor, A.J.; Rose, F.R.A.J.; Badylak, S.F.; Shakesheff, K.M.; White, L.J.

    2013-01-01

    The extracellular matrix (ECM) of mammalian tissues has been isolated, decellularized and utilized as a scaffold to facilitate the repair and reconstruction of numerous tissues. Recent studies have suggested that superior function and complex tissue formation occurred when ECM scaffolds were derived from site-specific homologous tissues compared with heterologous tissues. The objectives of the present study were to apply a stringent decellularization process to demineralized bone matrix (DBM), prepared from bovine bone, and to characterize the structure and composition of the resulting ECM materials and DBM itself. Additionally, we sought to produce a soluble form of DBM and ECM which could be induced to form a hydrogel. Current clinical delivery of DBM particles for treatment of bone defects requires incorporation of the particles within a carrier liquid. Differences in osteogenic activity, inflammation and nephrotoxicity have been reported with various carrier liquids. The use of hydrogel forms of DBM or ECM may reduce the need for carrier liquids. DBM and ECM hydrogels exhibited sigmoidal gelation kinetics consistent with a nucleation and growth mechanism, with ECM hydrogels characterized by lower storage moduli than the DBM hydrogels. Enhanced proliferation of mouse primary calvarial cells was achieved on ECM hydrogels, compared with collagen type I and DBM hydrogels. These results show that DBM and ECM hydrogels have distinct structural, mechanical and biological properties and have the potential for clinical delivery without the need for carrier liquids. PMID:23624219

  20. Biocompatible cellulose-based superabsorbent hydrogels with antimicrobial activity.

    PubMed

    Peng, Na; Wang, Yanfeng; Ye, Qifa; Liang, Lei; An, Yuxing; Li, Qiwei; Chang, Chunyu

    2016-02-10

    Current superabsorbent hydrogels commercially applied in the disposable diapers have disadvantages such as weak mechanical strength, poor biocompatibility, and lack of antimicrobial activity, which may induce skin allergy of body. To overcome these hassles, we have developed novel cellulose based hydrogels via simple chemical cross-linking of quaternized cellulose (QC) and native cellulose in NaOH/urea aqueous solution. The prepared hydrogel showed superabsorbent property, high mechanical strength, good biocompatibility, and excellent antimicrobial efficacy against Saccharomyces cerevisiae. The presence of QC in the hydrogel networks not only improved their swelling ratio via electrostatic repulsion of quaternary ammonium groups, but also endowed their antimicrobial activity by attraction of sections of anionic microbial membrane into internal pores of poly cationic hydrogel leading to the disruption of microbial membrane. Moreover, the swelling properties, mechanical strength, and antibacterial activity of hydrogels strongly depended on the contents of quaternary ammonium groups in hydrogel networks. The obtained data encouraged the use of these hydrogels for hygienic application such as disposable diapers.

  1. Difference between Chitosan Hydrogels via Alkaline and Acidic Solvent Systems

    PubMed Central

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-01-01

    Chitosan (CS) has generated considerable interest for its desirable properties and wide applications. Hydrogel has been proven to be a major and vital form in the applications of CS materials. Among various types of CS hydrogels, physical cross-linked CS hydrogels are popular, because they avoided the potential toxicity and sacrifice of intrinsic properties caused by cross-linking or reinforcements. Alkaline solvent system and acidic solvent system are two important solvent systems for the preparation of physical cross-linked CS hydrogels, and also lay the foundations of CS hydrogel-based materials in many aspects. As members of physical cross-linked CS hydrogels, gel material via alkaline solvent system showed significant differences from that via acidic solvent system, but the reasons behind are still unexplored. In the present work, we studied the difference between CS hydrogel via alkaline system and acidic system, in terms of gelation process, hydrogel structure and mechanical property. In-situ/pseudo in-situ studies were carried out, including fluorescent imaging of gelation process, which provided dynamic visualization. Finally, the reasons behind the differences were explained, accompanied by the discussion about design strategy based on gelation behavior of the two systems. PMID:27786262

  2. Poly(N-isopropylacrylamide) hydrogels with interpenetrating multiwalled carbon nanotubes for cell sheet engineering.

    PubMed

    Chen, Yu-Shuan; Tsou, Pei-Chun; Lo, Jem-Mau; Tsai, Hsieh-Chih; Wang, Yan-Zhen; Hsiue, Ging-Ho

    2013-10-01

    Hydrogels have been developed as artificial extracellular matrixes (ECMs) to mimic native tissue microenvironments for various applications. Unfortunately, poly(N-isopropylacrylamide) (PNIPAAM)-based hydrogels are not suitable for cell culturing and cell sheet preparation. Carbon nanotubes (CNTs), with their mechanical strength and electrical conductivity, have been considered as additives to increase the applicability of hydrogels to cell encapsulation and advance cardiac electrophysiological functions. A simple method for fabrication of PNIPAAM hydrogels interpenetrated with multiwalled CNTs (MWCNTs) as substrates for cell sheet preparation is reported. The results demonstrate that PNIPAAM hydrogels with interpenetrating MWCNTs still exhibit thermosensitive behavior. It is also found that epithelial Madin-Darby canine kidney (MDCK) cells can only attach and proliferate on MWCNT-interpenetrated PNIPAAM hydrogels. Furthermore, the PNIPAAM hydrogels with MWCNTs possess higher elastic moduli and hydrophobicities than those without MWCNTs, suggesting these two characteristics are necessary for the cells to attach to the hydrogel surfaces. Moreover, cell sheets can only be harvested from PNIPAAM hydrogels with MWCNTs because of their high ratio of cell attachment. Thus, this simple method provides sufficient mechanical strength to PNIPAAM hydrogels so that anchorage-dependent cells can be cultivated and provides a superior system for preparing cell sheets.

  3. Carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing.

    PubMed

    Zhang, Di; Zhou, Wei; Wei, Bing; Wang, Xin; Tang, Rupei; Nie, Jiemin; Wang, Jun

    2015-07-10

    The objective of this study was to develop a novel carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing. To prepare the crosslinked hydrogels, poly(vinyl alcohol) (PVA) was grafted with succinate acid to yield carboxyl-modified poly(vinyl alcohol) (PVA-COOH). Hydrogel films based on PVA-COOH and chitosan (CS) at different concentrations were crosslinked through the formation of amide linkages. The mechanical properties of these crosslinked hydrogel films in dry and swollen state were greatly improved with high swelling ratio. Water vapor and oxygen permeability evaluations indicated that crosslinked hydrogel films could maintain a moist environment over wound bed. Biocompatibility test showed the crosslinked hydrogels had no cytotoxicity and hemolytic potential. Gentamicin sulfate-loaded crosslinked hydrogel films showed sustained drug release profile, and could effectively suppress bacterial proliferation and protect wound from infection.

  4. Behaviors of acrylamide/itaconic acid hydrogels in uptake of uranyl ions from aqueous solutions

    SciTech Connect

    Karadag, E.; Saraydin, D.; Gueven, O.

    1995-12-01

    In this study, adsorptions of uranyl ions from two different aqueous uranyl solutions by acrylamide-itaconic acid hydrogels were investigated by a spectroscopic method. The hydrogels were prepared by irradiating with {gamma}-radiation. In the experiment of uranyl ions adsorption, Type II adsorption was found. One gram of acrylamide-itaconic acid hydrogels sorbed 178-219 mg uranyl ions from the solutions of uranyl acetate, 42-76 mg uranyl ions from the aqueous solutions of uranyl nitrate, while acrylamide hydrogel did not sorb any uranyl ion. For the hydrogel containing 40 mg of itaconic acid and irradiated to 3.73 kGy, swelling of the hydrogels was observed in water (1660%), in the aqueous solution of uranyl acetate (730%), and in the aqueous solution of uranyl nitrate (580%). Diffusions of water onto hydrogels were a non-Fickian type of diffusion, whereas diffusions of uranyl ions were a Fickian type of diffusion.

  5. Development of microbial resistant thermosensitive Ag nanocomposite (gelatin) hydrogels via green process.

    PubMed

    Manjula, Bandla; Varaprasad, Kokkarachedu; Sadiku, Rotimi; Ramam, Koduri; Reddy, G Venkata Subba; Raju, Konduru Mohana

    2014-04-01

    In this investigation, an ecofriendly method for the synthesis of silver nanoparticles (AgNPs) using biodegradable gelatin as a stabilizing agent is reported. Here, we prepared thermosensitive silver nanocomposite hydrogels composed of gelatin and N-isopropylacrylamide. In this green process AgNPs were formed from Ag(+) ions and reduced with leaf [Azadirachta indica (neem leaf)] extracts, resulting in a hydrogel network. The Ag(0) nanoparticles affect the hydrogel strength and improved the biological activity (inactivation effect of bacteria) of the biodegradable hydrogels. The resulted hydrogel structure, morphology, thermal, swelling behavior, degradation, and antibacterial properties were systematically investigated. The biodegradable thermosensitive silver nanocomposite hydrogels developed were tested for antibacterial activities. The results indicate that these biodegradable silver nanocomposite hydrogels are suitable potential candidates for antibacterial applications.

  6. Facile synthesis of antibacterial chitosan/CuO bio-nanocomposite hydrogel beads.

    PubMed

    Farhoudian, Sana; Yadollahi, Mehdi; Namazi, Hassan

    2016-01-01

    CuO nanoparticles were synthesized in situ during the formation of physically cross-linked chitosan hydrogel beads using sodium tripolyphosphate as the cross-linker. The aim of the study was to investigate whether these nanocomposite beads have the potential to be used in drug delivery applications. The formation of CuO nanoparticles (CuONPs) in the hydrogels was confirmed by X-ray diffraction and scanning electron microscopy studies. SEM micrographs revealed the formation of CuONPs with size range of 10-25 nm within the hydrogel matrix. Furthermore, the antibacterial and swelling properties of the beads were studied. The prepared nanocomposite hydrogels showed a pH sensitive swelling behavior. The CuO nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with neat hydrogel. The nanocomposite hydrogels demonstrated good antibacterial effects against Escherichia coli and Staphylococcus aureus bacteria.

  7. Pseudopeptide-Based Hydrogels Trapping Methylene Blue and Eosin Y.

    PubMed

    Milli, Lorenzo; Zanna, Nicola; Merlettini, Andrea; Di Giosia, Matteo; Calvaresi, Matteo; Focarete, Maria Letizia; Tomasini, Claudia

    2016-08-16

    We present herein the preparation of four different hydrogels based on the pseudopeptide gelator Fmoc-l-Phe-d-Oxd-OH (Fmoc=fluorenylmethyloxycarbonyl), either by changing the gelator concentration or adding graphene oxide (GO) to the water solution. The hydrogels have been analysed by rheological studies that demonstrated that pure hydrogels are slightly stronger compared to GO-loaded hydrogels. Then the hydrogels efficiency to trap the cationic methylene blue (MB) and anionic eosin Y (EY) dyes has been analyzed. MB is efficiently trapped by both the pure hydrogel and the GO-loaded hydrogel through π-π interactions and electrostatic interactions. In contrast, the removal of the anionic EY is achieved in less satisfactory yields, due to the unfavourable electrostatic interactions between the dye, the gelator and GO.

  8. Nanocellulose-alginate hydrogel for cell encapsulation.

    PubMed

    Park, Minsung; Lee, Dajung; Hyun, Jinho

    2015-02-13

    TEMPO-oxidized bacterial cellulose (TOBC)-sodium alginate (SA) composites were prepared to improve the properties of hydrogel for cell encapsulation. TOBC fibers were obtained using a TEMPO/NaBr/NaClO system at pH 10 and room temperature. The fibrillated TOBCs mixed with SA were cross-linked in the presence of Ca(2+) solution to form hydrogel composites. The compression strength and chemical stability of the TOBC/SA composites were increased compared with the SA hydrogel, which indicated that TOBC performed an important function in enhancing the structural, mechanical and chemical stability of the composites. Cells were successfully encapsulated in the TOBC/SA composites, and the viability of cells was investigated. TOBC/SA composites can be a potential candidate for cell encapsulation engineering. PMID:25458293

  9. Hydrogels Constructed from Engineered Proteins.

    PubMed

    Li, Hongbin; Kong, Na; Laver, Bryce; Liu, Junqiu

    2016-02-24

    Due to their various potential biomedical applications, hydrogels based on engineered proteins have attracted considerable interest. Benefitting from significant progress in recombinant DNA technology and protein engineering/design techniques, the field of protein hydrogels has made amazing progress. The latest progress of hydrogels constructed from engineered recombinant proteins are presented, mainly focused on biorecognition-driven physical hydrogels as well as chemically crosslinked hydrogels. The various bio-recognition based physical crosslinking strategies are discussed, as well as chemical crosslinking chemistries used to engineer protein hydrogels, and protein hydrogels' various biomedical applications. The future perspectives of this fast evolving field of biomaterials are also discussed. PMID:26707834

  10. Hydrogels Constructed from Engineered Proteins.

    PubMed

    Li, Hongbin; Kong, Na; Laver, Bryce; Liu, Junqiu

    2016-02-24

    Due to their various potential biomedical applications, hydrogels based on engineered proteins have attracted considerable interest. Benefitting from significant progress in recombinant DNA technology and protein engineering/design techniques, the field of protein hydrogels has made amazing progress. The latest progress of hydrogels constructed from engineered recombinant proteins are presented, mainly focused on biorecognition-driven physical hydrogels as well as chemically crosslinked hydrogels. The various bio-recognition based physical crosslinking strategies are discussed, as well as chemical crosslinking chemistries used to engineer protein hydrogels, and protein hydrogels' various biomedical applications. The future perspectives of this fast evolving field of biomaterials are also discussed.

  11. Hydrogel microparticles for biosensing

    PubMed Central

    Le Goff, Gaelle C.; Srinivas, Rathi L.; Hill, W. Adam; Doyle, Patrick S.

    2015-01-01

    Due to their hydrophilic, biocompatible, and highly tunable nature, hydrogel materials have attracted strong interest in the recent years for numerous biotechnological applications. In particular, their solution-like environment and non-fouling nature in complex biological samples render hydrogels as ideal substrates for biosensing applications. Hydrogel coatings, and later, gel dot surface microarrays, were successfully used in sensitive nucleic acid assays and immunoassays. More recently, new microfabrication techniques for synthesizing encoded particles from hydrogel materials have enabled the development of hydrogel-based suspension arrays. Lithography processes and droplet-based microfluidic techniques enable generation of libraries of particles with unique spectral or graphical codes, for multiplexed sensing in biological samples. In this review, we discuss the key questions arising when designing hydrogel particles dedicated to biosensing. How can the hydrogel material be engineered in order to tune its properties and immobilize bioprobes inside? What are the strategies to fabricate and encode gel particles, and how can particles be processed and decoded after the assay? Finally, we review the bioassays reported so far in the literature that have used hydrogel particle arrays and give an outlook of further developments of the field. PMID:26594056

  12. Properties of xyloglucan hydrogel as the biomedical sustained-release carriers.

    PubMed

    Chen, Didi; Guo, Pei; Chen, Sha; Cao, Yu; Ji, Wanzhen; Lei, Xia; Liu, Lina; Zhao, Peiguang; Wang, Ruihong; Qi, Chao; Liu, Yanli; He, Hongxuan

    2012-04-01

    This study introduces an easy method of preparing xyloglucan hydrogel from xyloglucan, which is purified from tamarind seed gum. Xyloglucan hydrogel was prepared in 2 wt% solution by treating with β-galactosidase. Physical and chemical properties (molecular mass, size and viscosity) of xyloglucan hydrogel and xyloglucan solution were tested for a comparison. Experiments of drug release in vitro and in vivo were operated to investigate the potentialities of xyloglucan hydrogel as the biomedical sustained-release carriers for drug delivery system. PMID:22354327

  13. A self-healing hydrogel formation strategy via exploiting endothermic interactions between polyelectrolytes.

    PubMed

    Ren, Ying; Lou, Ruyun; Liu, Xiaocen; Gao, Meng; Zheng, Huizhen; Yang, Ting; Xie, Hongguo; Yu, Weiting; Ma, Xiaojun

    2016-05-01

    We report a strategy to synthesize self-healing hydrogels via exploiting endothermic interactions between polyelectrolytes. Natural polysaccharides and their derivatives were used to form reversible polyelectrolyte complexes by selecting appropriately charged chemical groups and counterions. This simple and effective method to fabricate self-healing hydrogels will find applications in diverse fields such as surface coating and 3D printing. PMID:27078585

  14. Development of Hydrogels and Biomimetic Regulators as Tissue Engineering Scaffolds

    PubMed Central

    Shi, Junbin; Xing, Malcolm M. Q.; Zhong, Wen

    2012-01-01

    This paper reviews major research and development issues relating to hydrogels as scaffolds for tissue engineering, the article starts with a brief introduction of tissue engineering and hydrogels as extracellular matrix mimics, followed by a description of the various types of hydrogels and preparation methods, before a discussion of the physical and chemical properties that are important to their application. There follows a short comment on the trends of future research and development. Throughout the discussion there is an emphasis on the genetic understanding of bone tissue engineering application. PMID:24957963

  15. Thermosensitive hydrogel containing dexamethasone micelles for preventing postsurgical adhesion in a repeated-injury model.

    PubMed

    Wu, Qinjie; Wang, Ning; He, Tao; Shang, Jinfeng; Li, Ling; Song, Linjiang; Yang, Xi; Li, Xia; Luo, Na; Zhang, Wenli; Gong, Changyang

    2015-09-01

    Tissue adhesion is a common complication after surgery. In this work, a dexamethasone loaded polymeric micelles in thermosensitive hydrogel composite (Dex hydrogel) was prepared, which combined the anti-adhesion barrier with controlled release of anti-adhesion drug. Dexamethasone (Dex) was encapsulated in polymeric micelles (Dex micelles), and then the Dex micelles were loaded into biodegradable and thermosensitive hydrogel. The obtained Dex hydrogel showed a temperature-dependent sol-gel-sol phase transition behavior. The Dex hydrogel could form a non-flowing gel in situ upon subcutaneous injection and gradually degrade in about 20 days. In addition, Dex hydrogel was assigned for anti-adhesion studies in a more rigorous recurrent adhesion animal model. Compared with normal saline (NS) and Dex micelles group, tissue adhesions in hydrogel and Dex hydrogel group were significantly alleviated. In Dex hydrogel group, the media adhesion score is 0, which was dramatically lower than that in blank hydrogel group (2.50, P < 0.001). In histopathological examination and scanning electron microscopy (SEM) analysis, an integral neo-mesothelial cell layer with microvilli on their surface was observed, which revealed that the injured parietal and visceral peritoneum were fully recovered without the concerns of adhesion formation. Our results suggested that Dex hydrogel may serve as a potential anti-adhesion candidate.

  16. Thermosensitive hydrogel containing dexamethasone micelles for preventing postsurgical adhesion in a repeated-injury model

    PubMed Central

    Wu, Qinjie; Wang, Ning; He, Tao; Shang, Jinfeng; Li, Ling; Song, Linjiang; Yang, Xi; Li, Xia; Luo, Na; Zhang, Wenli; Gong, Changyang

    2015-01-01

    Tissue adhesion is a common complication after surgery. In this work, a dexamethasone loaded polymeric micelles in thermosensitive hydrogel composite (Dex hydrogel) was prepared, which combined the anti-adhesion barrier with controlled release of anti-adhesion drug. Dexamethasone (Dex) was encapsulated in polymeric micelles (Dex micelles), and then the Dex micelles were loaded into biodegradable and thermosensitive hydrogel. The obtained Dex hydrogel showed a temperature-dependent sol-gel-sol phase transition behavior. The Dex hydrogel could form a non-flowing gel in situ upon subcutaneous injection and gradually degrade in about 20 days. In addition, Dex hydrogel was assigned for anti-adhesion studies in a more rigorous recurrent adhesion animal model. Compared with normal saline (NS) and Dex micelles group, tissue adhesions in hydrogel and Dex hydrogel group were significantly alleviated. In Dex hydrogel group, the media adhesion score is 0, which was dramatically lower than that in blank hydrogel group (2.50, P < 0.001). In histopathological examination and scanning electron microscopy (SEM) analysis, an integral neo-mesothelial cell layer with microvilli on their surface was observed, which revealed that the injured parietal and visceral peritoneum were fully recovered without the concerns of adhesion formation. Our results suggested that Dex hydrogel may serve as a potential anti-adhesion candidate. PMID:26324090

  17. Designing the mechanical properties of peptide-based supramolecular hydrogels for biomedical applications

    NASA Astrophysics Data System (ADS)

    Li, Ying; Qin, Meng; Cao, Yi; Wang, Wei

    2014-05-01

    Hydrogels are a class of special materials that contain a large amount of water and behave like rubber. These materials have found broad applications in tissue engineering, cell culturing, regenerative medicine etc. Recently, the exploration of peptide-based supramolecular hydrogels has greatly expanded the repertoire of hydrogels suitable for biomedical applications. However, the mechanical properties of peptide-based hydrogels are intrinsically weak. Therefore, it is crucial to develop methods that can improve the mechanical stability of such peptide-based hydrogels. In this review, we explore the factors that determine or influence the mechanical stability of peptide-based hydrogels and summarize several key elements that may guide scientists to achieve mechanically improved hydrogels. In addition, we exemplified several methods that have been successfully developed to prepare hydrogels with enhanced mechanical stability. These mechanically strong peptide-based hydrogels may find broad applications as novel biomaterials. It is still challenging to engineer hydrogels in order to mimic the mechanical properties of biological tissues. More hydrogel materials with optimal mechanical properties suitable for various types of biological applications will be available in the near future.

  18. Substrate-Independent Robust and Heparin-Mimetic Hydrogel Thin Film Coating via Combined LbL Self-Assembly and Mussel-Inspired Post-Cross-linking.

    PubMed

    Ma, Lang; Cheng, Chong; He, Chao; Nie, Chuanxiong; Deng, Jie; Sun, Shudong; Zhao, Changsheng

    2015-12-01

    In this work, we designed a robust and heparin-mimetic hydrogel thin film coating via combined layer-by-layer (LbL) self-assembly and mussel-inspired post-cross-linking. Dopamine-grafted heparin-like/-mimetic polymers (DA-g-HepLP) with abundant carboxylic and sulfonic groups were synthesized by the conjugation of adhesive molecule, DA, which exhibited substrate-independent adhesive affinity to various solid surfaces because of the formation of irreversible covalent bonds. The hydrogel thin film coated substrates were prepared by a three-step reaction: First, the substrates were coated with DA-g-HepLP to generate negatively charged surfaces. Then, multilayers were obtained via LbL coating of chitosan and the DA-g-HepLP. Finally, the noncovalent multilayers were oxidatively cross-linked by NaIO4. Surface ATR-FTIR and XPS spectra confirmed the successful fabrication of the hydrogel thin film coatings onto membrane substrates; SEM images revealed that the substrate-independent coatings owned 3D porous morphology. The soaking tests in highly alkaline, acid, and concentrated salt solutions indicated that the cross-linked hydrogel thin film coatings owned high chemical resistance. In comparison, the soaking tests in physiological solution indicated that the cross-linked hydrogel coatings owned excellent long-term stability. The live/dead cell staining and morphology observations of the adhered cells revealed that the heparin-mimetic hydrogel thin film coated substrates had low cell toxicity and high promotion ability for cell proliferation. Furthermore, systematic in vitro investigations of protein adsorption, platelet adhesion, blood clotting, and blood-related complement activation confirmed that the hydrogel film coated substrates showed excellent hemocompatibility. Both the results of inhibition zone and bactericidal activity indicated that the gentamycin sulfate loaded hydrogel thin films had significant inhibition capability toward both Escherichia coli and

  19. Substrate-Independent Robust and Heparin-Mimetic Hydrogel Thin Film Coating via Combined LbL Self-Assembly and Mussel-Inspired Post-Cross-linking.

    PubMed

    Ma, Lang; Cheng, Chong; He, Chao; Nie, Chuanxiong; Deng, Jie; Sun, Shudong; Zhao, Changsheng

    2015-12-01

    In this work, we designed a robust and heparin-mimetic hydrogel thin film coating via combined layer-by-layer (LbL) self-assembly and mussel-inspired post-cross-linking. Dopamine-grafted heparin-like/-mimetic polymers (DA-g-HepLP) with abundant carboxylic and sulfonic groups were synthesized by the conjugation of adhesive molecule, DA, which exhibited substrate-independent adhesive affinity to various solid surfaces because of the formation of irreversible covalent bonds. The hydrogel thin film coated substrates were prepared by a three-step reaction: First, the substrates were coated with DA-g-HepLP to generate negatively charged surfaces. Then, multilayers were obtained via LbL coating of chitosan and the DA-g-HepLP. Finally, the noncovalent multilayers were oxidatively cross-linked by NaIO4. Surface ATR-FTIR and XPS spectra confirmed the successful fabrication of the hydrogel thin film coatings onto membrane substrates; SEM images revealed that the substrate-independent coatings owned 3D porous morphology. The soaking tests in highly alkaline, acid, and concentrated salt solutions indicated that the cross-linked hydrogel thin film coatings owned high chemical resistance. In comparison, the soaking tests in physiological solution indicated that the cross-linked hydrogel coatings owned excellent long-term stability. The live/dead cell staining and morphology observations of the adhered cells revealed that the heparin-mimetic hydrogel thin film coated substrates had low cell toxicity and high promotion ability for cell proliferation. Furthermore, systematic in vitro investigations of protein adsorption, platelet adhesion, blood clotting, and blood-related complement activation confirmed that the hydrogel film coated substrates showed excellent hemocompatibility. Both the results of inhibition zone and bactericidal activity indicated that the gentamycin sulfate loaded hydrogel thin films had significant inhibition capability toward both Escherichia coli and

  20. Synthesis and characterization of an in situ forming hydrogel using tyramine conjugated high methoxyl gum tragacanth.

    PubMed

    Tavakol, Moslem; Vasheghani-Farahani, Ebrahim; Mohammadifar, Mohammad Amin; Soleimani, Masoud; Hashemi-Najafabadi, Sameereh

    2016-02-01

    In this study, an enzyme catalyzed in situ forming hydrogel based on tyramine conjugated high methoxyl content gum tragacanth (TA-HMGT) was prepared and characterized. TA-HMGT was synthesized via heterogeneous ammonolysis of methyl ester groups of HMGT. Then, the hydrogel was prepared via horseradish peroxidase catalyzed coupling reaction in the presence of hydrogen peroxide. Hydrogel properties, such as gelation time, swelling/degradation behavior and rheological properties could be adjusted by tuning the gelation parameters and extent of tyramine conjugation. This system was a soft elastic hydrogel with appropriate biocompatibility. The fast gelation of the hydrogel is desirable for clinical applications. Also, in vitro bovine serum albumin release from the synthesized hydrogel showed good release profile with limited burst release.

  1. Radiation synthesis of superabsorbent poly(acrylic acid)-carrageenan hydrogels

    NASA Astrophysics Data System (ADS)

    Francis, Sanju; Kumar, Manmohan; Varshney, Lalit

    2004-04-01

    A series of superabsorbent hydrogels were prepared from carrageenan and partially neutralized acrylic acid by gamma irradiation at room temperature. The gel fraction, swelling kinetics and the equilibrium degree of swelling (EDS) of the hydrogels were studied. It was found that the incorporation of even 1% carrageenan (sodium salt) increases the EDS of the hydrogels from ˜320 to ˜800 g/g. Thermal analysis were carried out to determine the amount of free water and bound water in the hydrogels. Under optimum conditions, poly(acrylic acid)-carrageenan hydrogels with high gel fraction (˜80%) and very high EDS (˜800 g/g) were prepared gamma radiolytically from aqueous solution containing 15% partially neutralized acrylic acid and 1-5% carrageenan. The hydrogels were also found to be sensitive to the pH and the ionic strength of the medium.

  2. Development of CMC hydrogels loaded with silver nano-particles for medical applications.

    PubMed

    Hebeish, Ali; Hashem, M; El-Hady, M M Abd; Sharaf, S

    2013-01-30

    Innovative CMC-based hydrogels with great potentials for usage in medical area were principally synthesized as per two strategies .The first involved reaction of epichlorohydrin in alkaline medium containing silver nitrate to yield silver nano-particles (AgNPs)-loaded CMC hydrogel. While CMC acted as stabilizing for AgNPs, trisodium citrate was added to the reaction medium to assist CMC in establishing reduction of Ag(+) to AgNPs. The second strategy entailed preparation of CMC hydrogel which assists the in situ preparation of AgNPs under the same conditions. In both strategies, factors affecting the characterization of AgNPs-loaded CMC hydrogels were studied. Analysis and characterization of the so obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, EDX, UV-vis spectrophotometer and TEM. Antimicrobial activity of the hydrogels was examined and mechanisms involved in their synthesis were reported.

  3. Structural analysis of dextran-based hydrogels obtained chemoenzymatically.

    PubMed

    Ferreira, L; Figueiredo, M M; Gil, M H; Ramos, M A

    2006-04-01

    This work reports the results of structural analysis in novel dextran-acrylate (dexT70-VA) hydrogels generated chemoenzymatically. Porous structure as well as hydrogel surface and interior morphologies were evaluated by mercury intrusion porosimetry (MIP), nitrogen adsorption (NA), and scanning electron microscopy (SEM) analyses, as a function of the degree of substitution (DS), and initial water content used in the preparation of the hydrogel. MIP analysis showed that the overall networks were clearly macroporous with pore sizes ranging from 0.065 to 10 microm. As expected, the average pore size decreased as DS increased and as initial water content decreased. Moreover, the porosity values ranged from 75 up 90%, which shows that these hydrogels present an interconnected pore structure. Nitrogen adsorption analyses showed that the specific surface area of dexT70-VA hydrogels increased either by increasing the DS or by decreasing the initial water content of the hydrogel. SEM results revealed that the surface of hydrogels with lower DS presented either a porous structure or a polymeric "skin" covering the pores, whereas hydrogels with higher DS were totally porous. Furthermore, the interior morphology varied according to the DS and the initial water content of the hydrogels. Finally, the average pore size was also determined from the swelling of hydrogel using a theoretical model developed by Flory-Rehner. The comparison of the SEM and MIP results with the ones obtained by the equilibrium swelling theory of Flory-Rehner shows that this approach highly underestimates the average pore size. PMID:16211568

  4. Process for preparing negative plates for use in a dry charge battery

    SciTech Connect

    Wegner, P.C.

    1986-02-11

    This patent describes a process for the production of lead-containing negative plates for use in a dry charge battery. The process cnsists of drying wet negative plates while protecting them from oxidation. This improvement is accomplished by treating the wet negative plates prior to the drying operation with an aqueous soluton of an oxidation inhibiting agent selected from salicylic acid, and 2-naphtol. The plates are then protected against oxidation during drying; and dry negative plates are obtained which are resistant to the absorption of water from the atmosphere on storage but are wet immediately by battery acid in use.

  5. Bioactive Nanocomposite Poly (Ethylene Glycol) Hydrogels Crosslinked by Multifunctional Layered Double Hydroxides Nanocrosslinkers.

    PubMed

    Huang, Heqin; Xu, Jianbin; Wei, Kongchang; Xu, Yang J; Choi, Chun Kit K; Zhu, Meiling; Bian, Liming

    2016-07-01

    Poly (ethylene glycol) (PEG) based hydrogels have been widely used in many biomedical applications such as regenerative medicine due to their good biocompatibility and negligible immunogenicity. However, bioactivation of PEG hydrogels, such as conjugation of bioactive biomolecules, is usually necessary for cell-related applications. Such biofunctionalization of PEG hydrogels generally involves complicated and time-consuming bioconjugation procedures. Herein, we describe the facile preparation of bioactive nanocomposite PEG hydrogel crosslinked by the novel multifunctional nanocrosslinkers, namely polydopamine-coated layered double hydroxides (PD-LDHs). The catechol-rich PD-LDH nanosheets not only act as effective nanocrosslinkers reinforcing the mechanical strength of the hydrogel, but also afford the hydrogels with robust bioactivity and bioadhesion via the cortical-mediated couplings. The obtained nanocomposite PEG hydrogels with the multifunctional PD-LDH crosslinking domains show tunable mechanical properties, self-healing ability, and bioadhesion to biological tissues. Furthermore, these hydrogels also promote the sequestration of proteins and support the osteogenic differentiation of human mesenchymal stem cells without any further bio-functionalization. Such facile preparation of bioactive and bioadhesive PEG hydrogels have rarely been achieved and may open up a new avenue for the design of nanocomposite PEG hydrogels for biomedical applications. PMID:27061462

  6. Morphology, absorptivity and viscoelastic properties of mineralized PVP-CMC hydrogel

    NASA Astrophysics Data System (ADS)

    Saha, Nabanita; Shah, Rushita; Vyroubal, Radek; Kitano, Takeshi; Saha, Petr

    2013-04-01

    A simple liquid diffusion mineralization technique was applied for the incorporation of calcium carbonate (CaCO3) in PVP-CMC hydrogel. The hydrogel was prepared 6.5 mm thick to achieve around 1 mm thick sample after mineralization of hydrogel matrix with calcite. The calcite crystals were round shaped and organized as building blocks inside the porous three dimensional cross linked structure of the PVP-CMC hydrogel. The present study was designed to evaluate the properties of mineralized (calcite) hydrogel with respect to freshly prepared hydrogel and those swelled in water (H2O) after drying. The viscoelastic properties of swelled and mineralized samples were reported though the dry PVP-CMC hydrogel were swelled and mineralized with calcite until 150 min. It is observed that there is not much difference in elastic property of fresh and 60 min mineralized hydrogels but the values of elastic property are decreased in the case of swelled hydrogels. It is interesting that in case of swelled samples the values of complex viscosity (η*) are increased with the increase of swelling time after 90 min but in case of calcite hydrogel the values (η*) are gradually decreased with the increase of time.

  7. Antibacterial carboxymethyl cellulose/Ag nanocomposite hydrogels cross-linked with layered double hydroxides.

    PubMed

    Yadollahi, Mehdi; Namazi, Hassan; Aghazadeh, Mohammad

    2015-08-01

    This paper deals with the preparation of antibacterial nanocomposite hydrogels through the combination of carboxy methyl cellulose (CMC), layered double hydroxides (LDH), and silver nanoparticles (AgNPs). CMC-LDH hydrogels were prepared by intercalating CMC into different LDHs. Then, Ag/CMC-LDH nanocomposite hydrogels were prepared through in situ formation of AgNPs within the CMC-LDHs. XRD analysis confirmed the intercalating CMC into the LDH sheets and formation of intercalated structures, as well as formation of AgNPs within the CMC-LDHs. SEM and TEM micrographs indicated well distribution of AgNPs within the Ag/CMC-LDHs. The prepared hydrogels showed a pH sensitive swelling behavior. The Ag/CMC-LDH nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with CMC-LDHs. The antibacterial activity of CMC-LDHs increased considerably after formation of AgNPs and was stable for more than one month.

  8. Gram-positive antimicrobial activity of amino acid-based hydrogels.

    PubMed

    Irwansyah, I; Li, Yong-Qiang; Shi, Wenxiong; Qi, Dianpeng; Leow, Wan Ru; Tang, Mark B Y; Li, Shuzhou; Chen, Xiaodong

    2015-01-27

    Antimicrobial hydrogels are prepared based on the co-assembly of commercial Fmoc-phenylalanine and Fmoc-leucine, which act as the hydrogelator and antimicrobial building block, respectively. This co-assembled antimicrobial hydrogel is demonstrated to exhibit selective bactericidal activity for gram-positive bacteria while being biocompatible with normal mammalian cells, showing great potential as an antimicrobial coating for clinical anti-infective applications.

  9. Moisturizing effect of oleogel/hydrogel mixtures.

    PubMed

    Almeida, I F; Fernandes, A R; Fernandes, L; Pena Ferreira, M R; Costa, P C; Bahia, M F

    2008-01-01

    The aim of this study was to obtain new vehicles for topical formulations based on the mixture of hydrogels (aqueous systems) with oleogels (lipophilic systems). Several formulations were prepared using different oleogels mixed with polyacrylic acid hydrogel without addition of other ingredients. The moisturizing effect of the bigels was assessed along with the hydrogel and oleogels used in their preparation by carrying out an in vivo study with 14 healthy volunteers. Corneometer measurements were taken each hour during a five-hour period after product's application. Stability tests (storage at 20 and 40 degrees C for six months) and mechanical characterization were also carried out. Stability tests showed no modifications of the textural properties and appearance over a six-month period at 20 degrees C. At accelerated conditions, modifications of colour and textural properties were detected after six months' storage. While retaining the mechanical and sensory properties of the hydrogel, the bigels showed simultaneously an enhanced moisturizing effect, making them promising candidates for topical formulations.

  10. Nanostructured conducting polymer hydrogels for energy storage applications.

    PubMed

    Shi, Ye; Peng, Lele; Yu, Guihua

    2015-08-14

    Conducting polymer hydrogels are emerging as a promising class of polymeric materials for various technological applications, especially for energy storage devices due to their unique combination of advantageous features of conventional polymers and organic conductors. To overcome the drawbacks of conventional synthesis, new synthetic routes in which acid molecules are adopted as both crosslinkers and dopants have been developed for conducting polymer hydrogels with unique 3D hierarchical porous nanostructures, resulting in high electrical conductivity, large surface area, structural tunability and hierarchical porosity for rapid mass/charge transport. The newly developed conducting polymer hydrogels exhibit high performance when applied as active electrode materials for electrochemical capacitors or as functional binder materials for high-energy lithium-ion batteries. This feature article summarizes the synthesis of conducting polymer hydrogels, presents their applications in energy storage, and discusses further opportunities and challenges.

  11. Characterizing pore sizes and water structure in stimuli-responsive hydrogels

    SciTech Connect

    Hoffman, A.S.; Antonsen, K.P.; Ashida, T.; Bohnert, J.L.; Dong, L.C.; Nabeshima, Y.; Nagamatsu, S.; Park, T.G.; Sheu, M.S.; Wu, X.S.; Yan, Q.

    1993-12-31

    Hydrogels have been extensively investigated as potential matrices for drug delivery. In particular, hydrogels responsive to pH and temperature changes have been of greatest interest most recently. Proteins and peptide drugs are especially relevant for delivery from such hydrogel matrices due to the relatively {open_quotes}passive{close_quotes} and biocompatible microenvironment which should exist within the hydrogel aqueous pores. The large molecular size of many proteins requires an interconnected large pore structure. Furthermore, the gel pore {open_quotes}walls{close_quotes} should not provide hydrophobic sites for strong interactions with proteins. In the special case of ion exchange release the protein would be attracted by opposite charges on the polymer backbones. Therefore, it is important both to control and to characterize the pore structure and the water character within a hydrogel to be used or protein or peptide drug delivery. This talk will critically review techniques for estimating these two key parameters in hydrogels.

  12. Influence of polyelectrolyte on the thermosensitive property of PNIPAAm-based copolymer hydrogels.

    PubMed

    Zhang, Xian-Zheng; Chu, Chih-Chang

    2007-09-01

    A new family of poly(NIPAAm-co-2-acrylamido-2-methyl-1-propanesulfonic acid) [P(NIPAAm-co-AMPSA)] hydrogels was synthesized by incorporating negative charged AMPSA to the backbone of the PNIPAAm-based hydrogel. The effect of polyelectrolyte (i.e., PAMPSA) on the thermosensitive property of PNIPAAm hydrogels was investigated. It was found that P(NIPAAm-co-AMPSA) hydrogels exhibited unique honey-comb-like 3D porous structure having rigid cell wall as well as enhanced mechanical property. The incorporation of AMPSA into PNIPAAm backbones also led to a significant increase in swelling capability at room temperature when comparing to pure PNIPAAm hydrogels. In addition, the shrinking rate upon heating was significantly improved if the AMPSA content in P(NIPAAm-co-AMPSA) hydrogels was less than 10 wt%. PMID:17483894

  13. Oxidized pectin cross-linked carboxymethyl chitosan: a new class of hydrogels.

    PubMed

    Fan, Lihong; Sun, Yi; Xie, Weiguo; Zheng, Hua; Liu, Shuhua

    2012-01-01

    Oxidation of pectin was performed with sodium periodate to prepare pectin dialdehyde (PD). In this study we used the cross-linking reaction of the active aldehyde of PD and the amino of carboxymethyl chitosan (CMC) to prepare the hydrogels. By controlling the proportion of pectin dialdehyde and CMC we made different kinds of hydrogels. We systematically studied the characters of the hydrogels using Fourier transform infrared spectroscopy analysis of the pectin dialdehyde, CMC and the hydrogels, and also X-ray diffractometry and scanning electron microscopy analysis of the instrument of the hydrogels. Equilibrium swelling showed that the gels retained about 88-93% water. The water vapor transmission rate (WVTR) and the evaporation of water from gels showed that such hydrogels were optimal for maintaining a moist environment conducive for wound healing. Examination of the hemolytic potential showed that the hydrogels were nonhemolytic in nature. The hydrogels were non-toxic and blood-compatible. This hydrogel prepared from oxidized pectin and CMC without employing any extraneous cross-linking agents is expected to have potential as wound-dressing material.

  14. Spermidine cross-linked hydrogels as a controlled release biomimetic approach for cloxacillin.

    PubMed

    López-Cebral, Rita; Romero-Caamaño, Vanessa; Seijo, Begoña; Alvarez-Lorenzo, Carmen; Martín-Pastor, Manuel; Concheiro, Ángel; Landin, Mariana; Sanchez, Alejandro

    2014-07-01

    The intrinsic ability of albumin to bind active substances in the physiological fluids has been explored to endow hydrogels with improved capability to regulate drug release. To develop such biomimetic-functional hydrogels, it is critical that albumin conformation is not altered and that the protein remains retained inside the hydrogel keeping its conformational freedom, i.e., it should be not chemically cross-linked. Thus, the hydrogels were prepared with various proportions of albumin by physical cross-linking of anionic polysaccharides (gellan gum and chondroitin sulfate) with the cationic endogen polyamine spermidine under mild conditions in order to prevent albumin denaturation. Texture and swelling properties of hydrogels with various compositions were recorded, and the effect of the preparation variables was evaluated applying neurofuzzy logic tools for hydrogels prepared with and without albumin and associating the antibiotic cloxacillin. Developed hydrogel systems were extensively analyzed by means of nuclear magnetic resonance (NMR) to determine weak-to-medium and strong binding modes and the equilibrium constants of the albumin-cloxacillin association. NMR techniques were also employed to demonstrate the successful modulation of the cloxacillin release from the albumin-containing hydrogels. In vitro microbiological tests carried out with Staphylococcus aureus and Staphylococcus epidermidis confirmed the interest of the albumin-containing hydrogels as efficient platforms for cloxacillin release in its bioactive form.

  15. Spermidine cross-linked hydrogels as a controlled release biomimetic approach for cloxacillin.

    PubMed

    López-Cebral, Rita; Romero-Caamaño, Vanessa; Seijo, Begoña; Alvarez-Lorenzo, Carmen; Martín-Pastor, Manuel; Concheiro, Ángel; Landin, Mariana; Sanchez, Alejandro

    2014-07-01

    The intrinsic ability of albumin to bind active substances in the physiological fluids has been explored to endow hydrogels with improved capability to regulate drug release. To develop such biomimetic-functional hydrogels, it is critical that albumin conformation is not altered and that the protein remains retained inside the hydrogel keeping its conformational freedom, i.e., it should be not chemically cross-linked. Thus, the hydrogels were prepared with various proportions of albumin by physical cross-linking of anionic polysaccharides (gellan gum and chondroitin sulfate) with the cationic endogen polyamine spermidine under mild conditions in order to prevent albumin denaturation. Texture and swelling properties of hydrogels with various compositions were recorded, and the effect of the preparation variables was evaluated applying neurofuzzy logic tools for hydrogels prepared with and without albumin and associating the antibiotic cloxacillin. Developed hydrogel systems were extensively analyzed by means of nuclear magnetic resonance (NMR) to determine weak-to-medium and strong binding modes and the equilibrium constants of the albumin-cloxacillin association. NMR techniques were also employed to demonstrate the successful modulation of the cloxacillin release from the albumin-containing hydrogels. In vitro microbiological tests carried out with Staphylococcus aureus and Staphylococcus epidermidis confirmed the interest of the albumin-containing hydrogels as efficient platforms for cloxacillin release in its bioactive form. PMID:24921673

  16. Crosslinking metal nanoparticles into the polymer backbone of hydrogels enables preparation of soft, magnetic field-driven actuators with muscle-like flexibility.

    PubMed

    Fuhrer, Roland; Athanassiou, Evagelos Kimon; Luechinger, Norman Albert; Stark, Wendelin Jan

    2009-03-01

    The combination of force and flexibility is at the core of biomechanics and enables virtually all body movements in living organisms. In sharp contrast, presently used machines are based on rigid, linear (cylinders) or circular (rotator in an electrical engine) geometries. As a potential bioinspired alternative, magnetic elastomers can be realized through dispersion of micro- or nanoparticles in polymer matrices and have attracted significant interest as soft actuators in artificial organs, implants, and devices for controlled drug delivery. At present, magnetic particle loss and limited actuator strength have restricted the use of such materials to niche applications. We describe the direct incorporation of metal nanoparticles into the backbone of a hydrogel and application as an ultra-flexible, yet strong magnetic actuator. Covalent bonding of the particles prevents metal loss or leaching. Since metals have a far higher saturation magnetization and higher density than oxides, the resulting increased force/volume ratio afforded significantly stronger magnetic actuators with high mechanical stability, elasticity, and shape memory effect.

  17. Hydrogel Biomaterials: A Smart Future?

    PubMed Central

    Kopeček, Jindřich

    2007-01-01

    Hydrogels were the first biomaterials developed for human use. The state-of-the-art and potential for the future are discussed. Recently, new designs have produced mechanically strong synthetic hydrogels. Protein based hydrogels and hybrid hydrogels containing protein domains present a novel advance; such biomaterials may self-assemble from block or graft copolymers containing biorecognition domains. One of the domains, the coiled-coil, ubiquitously found in nature, has been used as an example to demonstrate the developments in the design of smart hydrogels. The application potential of synthetic, protein-based, DNA-based, and hybrid hydrogels bodes well for the future of this class of biomaterials. PMID:17697712

  18. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    NASA Astrophysics Data System (ADS)

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-01

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels' network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  19. Antimicrobial properties of nanostructured hydrogel webs containing silver.

    PubMed

    Wu, Jian; Hou, Shuyu; Ren, Dacheng; Mather, Patrick T

    2009-09-14

    The need exists for biomaterials that prevent biofilm formation and associated infections. In this report, we have studied the synthesis, processing, and antimicrobial behavior of new silver-containing thermoplastic hydrogel nanofibrous webs. Thermoplastic hydrogels were synthesized from multiblock PEG-POSS polyurethanes (PEG: poly(ethylene gylcol); POSS: polyhedral oligosilsesquioxane) and electrospun into nanofibrous webs (diameter approximately 150 nm), with or without AgNO(3). The nanofibrous hydrogels exhibited unusual shrinkage during water uptake, yielding a uniquely dense structure compared to hydrogels prepared from cast films. Antimicrobial activity was examined using exposure to Escherichia coli with daily refreshment of medium and inoculation to a controlled cell density. Nanofibrous hydrogels without silver featured the most rapid and most extensive biofilm formation, while the silver-containing nanofibrous hydrogel featured outstanding biofilm resistance, with biofilm formation taking hold only after 14 days of incubation in daily refreshed bacterial cultures. We envision application of the unique antimicrobial hydrogels as wound dressings that combine sustained bactericidal properties and lack of volumetric swelling during water uptake.

  20. Polymer hydrogels: Chaperoning vaccines

    NASA Astrophysics Data System (ADS)

    Staats, Herman F.; Leong, Kam W.

    2010-07-01

    A cationic nanosized hydrogel (nanogel) shows controlled antigen delivery in vivo following intranasal administration and hence holds promise for a clinically effective adjuvant-free and needle-free vaccine system.

  1. Preparation and Charge Density in (Co, Fe)-Doped La-Ca-Based Chromite

    NASA Astrophysics Data System (ADS)

    Saravanan, R.; Thenmozhi, N.; Fu, Yen-Pei

    2016-08-01

    Transition metal-doped lanthanum chromites (La0.8Ca0.2)(Cr0.9- x Co0.1Fe x )O3 ( x = 0.03, 0.06, 0.09, 0.12) have been synthesized by solid state reaction method. The synthesized samples were characterized for their structural properties using powder x-ray diffraction analysis, which shows that the grown samples are orthorhombic in structure with single phase. The nature of bonding and the charge distribution of the grown samples have been analyzed by maximum entropy method. Further, the samples were characterized for their optical and magnetic properties using ultraviolet-visible spectra and vibrating sample magnetometry. The microstructural studies were carried by scanning electron microscopy/electron dispersive x-ray spectroscopy techniques. From the optical absorption spectra, it was found that the energy band gap of the samples ranges from 2.135 eV to 2.405 eV. From vibrating sample magnetometer measurements, ferromagnetic like behaviour with large coercive field was observed for Fe doping concentration of x = 0.12. Since the doped lanthanum chromites have good mechanical properties and electrical conductivity at high temperature, these materials are used in solid oxide fuel cells.

  2. Preparation of pH sensitive insulin-loaded nano hydrogels and evaluation of insulin releasing in different pH conditions.

    PubMed

    Karnoosh-Yamchi, Jalil; Mobasseri, Majid; Akbarzadeh, Abolfazl; Davaran, Soodabeh; Ostad-Rahimi, Ali Reza; Hamishehkar, Hamed; Salehi, Roya; Bahmani, Zahra; Nejati-Koshki, Kazem; Darbin, Akbar; Rahmati-Yamchi, Mohammad

    2014-10-01

    In the recent years, temperature and pH-sensitive hydrogels were developed as suitable carriers for drug delivery. In this study, four different pH-sensitive nanohydrogels were designed for an oral insulin delivery modeling. NIPAAm-MAA-HEM copolymers were synthesized by radical chain reaction with 80:8:12 ratios respectively. Reactions were carried out in four conditions including 1,4-dioxan and water as two distinct solution under nitrogen gas-flow. The copolymers were characterized with FT-IR, SEM and TEM. Copolymers were loaded with regular insulin by modified double emulsion method with ratio of 1:10. Release study carried out in pH 1.2 and pH 6.8 at 37 °C. For pH 6.8 and pH 1.2, 2 mg of the insulin loaded nanohydrogels was float in a beaker containing 100 mL of PBS with pH 6.8 and 100 mL of HCl solution with pH 1.2, respectively. Sample collection was done in different times and HPLC was used for analysis of samples using water/acetonitrile (65/35) as the mobile phase. Nanohydrogels synthesis reaction yield was 95 %, HPLC results showed that loading in 1,4-dioxan without cross-linker nanohydrogels was more than others, also indicated that the insulin release of 1,4-dioxan without cross-linker nanohydrogels at acidic pH is less, but in pH 6.8 is the most. Results showed that by opting suitable polymerization method and selecting the best nanohydrogels, we could obtain a suitable insulin loaded nanohydrogels for oral administration. PMID:24996289

  3. Facile fabrication processes for hydrogel-based microfluidic devices made of natural biopolymers

    PubMed Central

    Yajima, Yuya; Yamada, Masumi; Yamada, Emi; Iwase, Masaki; Seki, Minoru

    2014-01-01

    We present facile strategies for the fabrication of two types of microfluidic devices made of hydrogels using the natural biopolymers, alginate, and gelatin as substrates. The processes presented include the molding-based preparation of hydrogel plates and their chemical bonding. To prepare calcium-alginate hydrogel microdevices, we suppressed the volume shrinkage of the alginate solution during gelation using propylene glycol alginate in the precursor solution along with sodium alginate. In addition, a chemical bonding method was developed using a polyelectrolyte membrane of poly-L-lysine as the electrostatic glue. To prepare gelatin-based microdevices, we used microbial transglutaminase to bond hydrogel plates chemically and to cross-link and stabilize the hydrogel matrix. As an application, mammalian cells (fibroblasts and vascular endothelial cells) were cultivated on the microchannel surface to form three-dimensional capillary-embedding tissue models for biological research and tissue engineering. PMID:24803964

  4. An Improved Cryosection Method for Polyethylene Glycol Hydrogels Used in Tissue Engineering

    PubMed Central

    Ruan, Jia-Ling; Tulloch, Nathaniel L.; Muskheli, Veronica; Genova, E. Erin; Mariner, Peter D.; Anseth, Kristi S.

    2013-01-01

    The high water content of hydrogels allows these materials to closely mimic the native biological extracellular conditions, but it also makes difficult the histological preparation of hydrogel-based bioengineered tissue. Paraffin-embedding techniques require dehydration of hydrogels, resulting in substantial collapse and deformation, whereas cryosectioning is hampered by the formation of ice crystals within the hydrogel material. Here, we sought to develop a method to obtain good-quality cryosections for the microscopic evaluation of hydrogel-based tissue-engineered constructs, using polyethylene glycol (PEG) as a test hydrogel. Conventional sucrose solutions, which dehydrate cells while leaving extracellular water in place, produce a hydrogel block that is brittle and difficult to section. We therefore replaced sucrose with multiple protein-based and nonprotein-based solutions as cryoprotectants. Our analysis demonstrated that overnight incubation in bovine serum albumin (BSA), fetal bovine serum (FBS), polyvinyl alcohol (PVA), optimum cutting temperature (OCT®) compound, and Fisher HistoPrep frozen tissue-embedding media work well to improve the cryosectioning of hydrogels. The protein-based solutions give background staining with routine hematoxylin and eosin, but the use of nonprotein-based solutions PVA and OCT reduces this background by 50%. These methods preserve the tissue architecture and cellular details with both in vitro PEG constructs and in constructs that have been implanted in vivo. This simple hydrogel cryosectioning technique improves the methodology for creation of good-quality histological sections from hydrogels in multiple applications. PMID:23448137

  5. Diffusion and transfer of antibody proteins from a sugar-based hydrogel.

    PubMed

    Markowitz, M A; Turner, D C; Martin, B D; Gaber, B P

    1997-01-01

    Diffusion of antibody protein from hydrogel films and hydrogel encapsulated in a microcapillary was studied. Thin hydrogel films were formed by crosslinking 6-acryloyl-B-O-methylgalactoside with N,N'-methylene-bis-acrylamide and the diffusive transport of monoclonal antimouse IgG-FITC into and out of the hydrate films was measured. Diffusion coefficients in 2 and 4% crosslinked hydrogel films were measured. The measured diffusion constants determined for IgG in both the 2 and 4% hydrogel films were comparable to the free diffusion of IgG in bulk water (Dmean approximately 10(-7) cm2/s). In addition, 2% crosslinked hydrogels were prepared in a capillary tube and the transport of antimouse IgG-FITC into and out of the hydrated hydrogel was measured. Kinetic analysis indicated that the protein transport through the capillary hydrogel was faster than would be expected for a simple diffusion process. Finally, by utilizing the diffusion of antibody from the capillary hydrogel, transfer of antibody to a silica surface was demonstrated. A capillary hydrogel loaded with antimouse IgG-FITC was used to transfer the protein to a silica surface forming a 30-micron spot of antibody, which was imaged using fluorescence microscopy. These results may lead to the development of a nonlithographic method of patterning antibodies on surfaces for use in integrated microimmunosensors.

  6. Thermo-responsive devices using poly(vinyl methyl ether) hydrogels

    SciTech Connect

    Kishi, R.; Ichijo, H.; Hirasa, O.

    1993-10-01

    Aqueous solution of poly(vinyl methyl ether) (PVME) shows phase transition around 38 C. PVME hydrogel cross-linked by gamma-ray irradiation is also a thermally responsive hydrogel and undergoes volume change at the same temperature; it swells below and shrinks above 38 C. PVME hydrogel prepared near phase transition temperature has heterogeneous and macroporous structure. The volume change of the macroporous hydrogel takes place rapidly with changing temperature. An attempt has been made to develop thermally activated chemomechanical devices such as an artificial muscle model, an automatic separation system, an artificial finger model, and a photo-responsive device.

  7. Friction properties of novel PVP/PVA blend hydrogels as artificial cartilage.

    PubMed

    Ma, Ruyin; Xiong, Dangsheng; Miao, Feng; Zhang, Jinfeng; Peng, Yan

    2010-06-01

    In this work, novel polyvinylpyrrolidone (PVP)/polyvinylalcohol (PVA) blend hydrogels were prepared by repeated freezing-thawing cycles. The factors that influenced friction properties of blend hydrogels, such as PVP content, contact load, sliding speed, and lubrication condition, were mainly studied by sliding with stainless steel ball. The results showed that friction coefficients of the PVP/PVA blend hydrogels were definitely dependent on such influence factors. The friction system consisting of blend hydrogel and stainless steel ball nearly exhibited a mixed lubrication regime especially under bovine serum lubrication, and it can be proposed as a promising method to reduce wear of the prosthesis.

  8. Magnetic hydrogel nanocomposites and composite nanoparticles--a review of recent patented works.

    PubMed

    Daniel-da-Silva, Ana L; Carvalho, Rui S; Trindade, Tito

    2013-06-01

    Magnetic hydrogel nanocomposites and composite nanoparticles form a class of soft materials with remote controllable properties that have attracted great attention due to their potential use in diverse applications. These include medical applications such as controlled drug delivery, clinical imaging and cancer hyperthermia and ecological applications as well, such as wastewater treatment. The present review provides an overview of the patents disclosed and research work developed in the last decade on magnetic hydrogel nanocomposites and magnetic hydrogel composite nanoparticles envisaging the above mentioned applications. In this context, recent patented advances on chemical methods for the preparation of bulk hydrogel nanocomposites and composite nanoparticles will be reviewed. PMID:23763267

  9. Nanocomposite hydrogels for biomedical applications

    PubMed Central

    Gaharwar, Akhilesh K.

    2014-01-01

    Hydrogels mimic native tissue microenvironment due to their porous and hydrated molecular structure. An emerging approach to reinforce polymeric hydrogels and to include multiple functionalities focuses on incorporating nanoparticles within the hydrogel network. A wide range of nanoparticles, such as carbon-based, polymeric, ceramic, and metallic nanomaterials can be integrated within the hydrogel networks to obtain nanocomposites with superior properties and tailored functionality. Nanocomposite hydrogels can be engineered to possess superior physical, chemical, electrical, and biological properties. This review focuses on the most recent developments in the field of nanocomposite hydrogels with emphasis on biomedical and pharmaceutical applications. In particular, we discuss synthesis and fabrication of nanocomposite hydrogels, examine their current limitations and conclude with future directions in designing more advanced nanocomposite hydrogels for biomedical and biotechnological applications. PMID:24264728

  10. Processing and characterisation of a novel electropolymerized silk fibroin hydrogel membrane.

    PubMed

    Wang, Hai-Yan; Zhang, Yu-Qing

    2014-01-01

    Silk fibroin can be made into various forms of biocompatible medical materials, including hydrogel due to its excellent properties. Here, we report a novel method for the preparation of electropolymerized silk fibroin hydrogel membrane (ESFHM), which is formed on a nanoporous film as a barrier using a homemade device at a higher DC voltage. Regenerated silk fibroin solution in Tris buffer (pH 6.55-7.55) was added into a reservoir with a negative charge, and the silk molecules migrated toward the positive charge at 80VDC, resulting in the formation of the ESFHM on the barrier film. Barrier film with a MWCO of 10 kDa is favourable to the formation of the ESFHM. Semi-transparent ESFHM with a swelling ratio of 1056.4% predominantly consisted of a mixture of β-sheets and α-helix crystalline structures. SEM studies revealed that the ESFHM consisted of a 3D mesh structure woven by a chain of silk fibroin nanoparticles with a size of approximately 30 nanometres, similar to a pearl necklace. In vitro studies indicated that the ESFHM was degradable and was sufficient for cell adhesion and growth. Thus, ESFHM is a promising candidate for loading bioactive protein and appropriate cells, as artificial skin or for use in transplantation.

  11. Critical review of radiation processing of hydrogel and polysaccharide

    NASA Astrophysics Data System (ADS)

    Makuuchi, K.

    2010-03-01

    Radiation processing of an aqueous solution of polymer initiated by rad OH radicals formed by radiolysis of water is applied for preparation of hydrogel wound dressing and plant growth promoter. Recently, Fenton reagent that generates rad OH radicals was successfully applied to synthesize PVP hydrogel. The Fenton reaction also can be applied to the depolymerization of chitosan. These progresses in the syntheses of hydrogel and oligo-chitosan by radiation and non-radiation methods such as hydrolysis, oxidative degradation, photolysis, sonolysis and degradation by microwave are reviewed to survey a possibility to reduce the costs of production. Radiation synthesized hydrogel should target value-added medical products because only radiation can crosslink and sterilize simultaneously. Oligo-chitosan can be produced economically by irradiation of solid chitin by Fenton reagent, if necessary.

  12. Viscoelastic Properties and Morphology of Mumio-based Medicated Hydrogels

    NASA Astrophysics Data System (ADS)

    Zandraa, Oyunchimeg; Jelínková, Lenka; Roy, Niladri; Sáha, Tomáš; Kitano, Takeshi; Saha, Nabanita

    2011-07-01

    Novel medicated hydrogels were prepared (by moist heat treatment) with PVA, agar, mumio, mare's milk (MM), seabuckthorn oil (SB oil) and salicylic acid (SA) for wound dressing/healing application. Scanning electron micrographs (SEM) show highly porous structure of these hydrogels. The swelling behaviour of the hydrogels in physiological solution displays remarkable liquid absorption property. The knowledge obtained from rheological investigations of these-systems may be highly useful for the characterization of the newly developed topical formulations. In the present study, an oscillation frequency sweep test was used for the evaluation of storage modulus (G'), loss modulus (G″), and complex viscosity (η*) of five different formulations, over an angular frequency range from 0.1 to 100 rad.s-1. The influence of healing agents and swelling effect on the rheological properties of mumio-based medicated hydrogels was investigated to judge its application on uneven surface of body.

  13. Saccharides and temperature dual-responsive hydrogel layers for harvesting cell sheets.

    PubMed

    Guo, Bingbing; Pan, Guoqing; Guo, Qianping; Zhu, Caihong; Cui, Wenguo; Li, Bin; Yang, Huilin

    2015-01-14

    Saccharides and temperature dual-responsive hydrogels have been prepared based on PNIPAAm copolymers containing phenylboronic acid (PBA) groups and used for harvesting cell sheets. The cell sheet could be released from the hydrogel layer at 37 °C simply by increasing sugar concentration, and could be more efficiently released at a lower temperature and elevated sugar concentration.

  14. Structure of Block Copolymer Hydrogel Formed by Complex Coacervate Process

    NASA Astrophysics Data System (ADS)

    Choi, Soohyung; Ortony, Julia; Krogstad, Daniel; Spruell, Jason; Lynd, Nathaniel; Han, Songi; Kramer, Edward

    2012-02-01

    Complex coacervation occurs when oppositely charged polyelectrolytes associate in solution, forming dense micron-sized droplets. Hydrogels with coacervate block domains were formed by mixing two ABA and A'BA' triblock copolymer solutions in water where the A and A' blocks are oppositely charged. Small-angle neutron scattering (SANS) was used to investigate the structure of hydrogels formed by ABA triblock copolymers (A block: poly(allyl glycidyl ether) functionalized with guanidinium (A) or sulfonate (A'), B block: poly(ethylene oxide)). By using an appropriate fitting model, structural information such as coacervate core block radius and water volume fraction w can be extracted from SANS data. The results reveal that w in the coacervate core block was significantly higher than in conventional triblock copolymer hydrogels where microphase separation is driven by the hydrophobicity of the core-forming blocks.

  15. Development of novel biodegradable Au nanocomposite hydrogels based on wheat: for inactivation of bacteria.

    PubMed

    Jayaramudu, Tippabattini; Raghavendra, Gownolla Malegowd; Varaprasad, Kokkarachedu; Sadiku, Rotimi; Raju, Konduru Mohana

    2013-02-15

    The design and fabrication of novel biodegradable gold nanocomposites hydrogels were developed as antibacterial agent. Biodegradable gold nanocomposite hydrogels were developed by using acrylamide (AM) and wheat protein isolate (WPI). The gold nanoparticles were prepared as a gold colloid by reducing HAuCl(4)·XH(2)O with leaf extracts of Azadirachta indica (neem leaf) that formed hydrogel network. The characterization of developed biodegradable hydrogels were studied using fourier transforms infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The biodegradable gold nanoparticle composite hydrogels developed were tested for antibacterial properties. The results indicate that these biodegradable gold nanocomposite hydrogels can be used as potential candidates for antibacterial applications.

  16. Efficient inhibition of colorectal peritoneal carcinomatosis by drug loaded micelles in thermosensitive hydrogel composites

    NASA Astrophysics Data System (ADS)

    Gong, Changyang; Wang, Cheng; Wang, Yujun; Wu, Qinjie; Zhang, Doudou; Luo, Feng; Qian, Zhiyong

    2012-05-01

    In this work, we aim to develop a dual drug delivery system (DDDS) of self-assembled micelles in thermosensitive hydrogel composite to deliver hydrophilic and hydrophobic drugs simultaneously for colorectal peritoneal carcinomatosis (CRPC) therapy. In our previous studies, we found that poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCEC) copolymers with different molecular weight and PEG/PCL ratio could be administered to form micelles or thermosensitive hydrogels, respectively. Therefore, the DDDS was constructed from paclitaxel (PTX) encapsulated PCEC micelles (PTX-micelles) and a fluorouracil (Fu) loaded thermosensitive PCEC hydrogel (Fu-hydrogel). PTX-micelles were prepared by self-assembly of biodegradable PCEC copolymer (Mn = 3700) and PTX without using any surfactants or excipients. Meanwhile, biodegradable and injectable thermosensitive Fu-hydrogel (Mn = 3000) with a lower sol-gel transition temperature at around physiological temperature was also prepared. The obtained PTX-micelles in thermosensitive Fu-hydrogel (PTX-micelles-Fu-hydrogel) composite is a free-flowing sol at ambient temperature and rapidly turned into a non-flowing gel at physiological temperature. In addition, the results of cytotoxicity, hemolytic study, and acute toxicity evaluation suggested that the PTX-micelles-Fu-hydrogel was non-toxic and biocompatible. In vitro release behaviors of PTX-micelles-Fu-hydrogel indicated that both PTX and Fu have a sustained release behavior. Furthermore, intraperitoneal application of PTX-micelles-Fu-hydrogel effectively inhibited growth and metastasis of CT26 peritoneal carcinomatosis in vivo (p < 0.001), and induced a stronger antitumor effect than that of Taxol® plus Fu (p < 0.001). The pharmacokinetic study indicated that PTX-micelles-Fu-hydrogel significantly increased PTX and Fu concentration and residence time in peritoneal fluids compared with Taxol® plus Fu group. Thus, the results suggested the micelles-hydrogel DDDS may

  17. Injectable Hydrogel Composite Based Gelatin-PEG and Biphasic Calcium Phosphate Nanoparticles for Bone Regeneration

    NASA Astrophysics Data System (ADS)

    Van, Thuy Duong; Tran, Ngoc Quyen; Nguyen, Dai Hai; Nguyen, Cuu Khoa; Tran, Dai Lam; Nguyen, Phuong Thi

    2016-05-01

    Gelatin hydrogels have recently attracted much attention for tissue regeneration because of their biocompatibility. In this study, we introduce poly-ethylene glycol (PEG)—grafted gelatin containing tyramine moieties which have been utilized for in situ enzyme-mediated hydrogel preparation. The hydrogel can be used to load nanoparticles of biphasic calcium phosphate, a mixture of hydroxyapatite and β-tricalcium phosphate, and forming injectable bio-composites. Proton nuclear magnetic resonance (1H NMR) spectra indicated that tyramine-functionalized polyethylene glycol-nitrophenyl carbonate ester was conjugated to the gelatin. The hydrogel composite was rapidly formed in situ (within a few seconds) in the presence of horseradish peroxidase and hydrogen peroxide. In vitro experiments with bio-mineralization on the hydrogel composite surfaces was well-observed after 2 weeks soaking in simulated body fluid solution. The obtained results indicated that the hydrogel composite could be a potential injectable material for bone regeneration.

  18. Performance improvement of injectable poly(ethylene glycol) dimethacrylate-based hydrogels with finely dispersed hydroxyapatite.

    PubMed

    Zhou, Ziyou; Ren, Yongjuan; Yang, Dongzhi; Nie, Jun

    2009-06-01

    Injectable hydrogels are attractive materials for biomedical application. In this work, a chemical mixing technique was developed to promote the dispersion of hydroxyapatite (HA) in injectable poly(ethylene glycol) dimethacrylate (PEGDMA)-based hydrogels. Nano-sized HA particles were distributed homogenously within the organic network, whereby HA crystals were formed in the presence of PEGDMA macromers. In addition, hydrogels were also prepared by physical mixing of dry HA particles with PEGDMA, as a comparison. Transmission electron microscopy was used to evaluate the morphology and crystal structure of HA formed in the PEGDMA aqueous solution before polymerization. According to Fourier transform infrared spectra and x-ray diffraction results, hydrogels prepared by different methods have similar components and crystal structures. Scanning electron microscopy was used to observe the hydrogels' morphology, which showed that HA in hydrogels made by chemical mixing was well dispersed and nano sized. Mechanical evaluation indicated that the mean value of the compressive strength and modulus of hydrogels prepared by physical mixing were 0.137 MPa and 0.518 MPa, respectively, while those of hydrogels prepared by chemical mixing were 0.290 MPa and 0.696 MPa, respectively. Furthermore, temperature measurement showed that the mean value of the maximum temperature in the crosslinking process of hydrogels made by chemical mixing was 38.0 degrees C, which was significantly lower than that of for hydrogels made by physical mixing (38.6 degrees C). The results indicated that the performance of composite hydrogels could be promoted by chemical mixing of the inorganic network into a polymer network.

  19. Multi-arm PEG/silica hydrogel for sustained ocular drug delivery.

    PubMed

    Lu, Changhai; Zahedi, Payam; Forman, Adam; Allen, Christine

    2014-01-01

    In the present study, a series of sustained drug delivery multiarm poly(ethylene glycol) (PEG)/silica hydrogels were prepared and characterized. The hydrogels were formed by hydrolysis and condensation of poly(4-arm PEG silicate) using the sol-gel method. The relationships between water content in the PEG/silica hydrogel and stability as well as rheological properties were evaluated. Scanning electron microscopy analysis of the PEG/silica hydrogels revealed water content-dependent changes in microstructure. An increase in water content resulted in larger pores within the hydrogel, longer gelation time and higher viscosity. The PEG/silica hydrogels were loaded with dexamethasone (DMS) or dexamethasone sodium phosphate (DMSP), drugs that are hydrophobic and hydrophilic in nature, respectively. Evaluation of in vitro release revealed a zero-order release profile for DMS over the first 6 days, suggesting that degradation of the silica hydrogel matrix was the primary mechanism of drug release. It was also found that the drug-release profile could be tailored by varying the water content used during hydrogel preparation. In contrast, more than 90% of DMSP was released within 1 h, suggesting that DMSP release was only controlled by diffusion. Overall, results from this study indicate that PEG/silica hydrogels may be promising drug-eluting depot materials for the sustained delivery of hydrophobic, ophthalmic drugs. PMID:24285503

  20. Iota-Carrageenan-based biodegradable Ag0 nanocomposite hydrogels for the inactivation of bacteria.

    PubMed

    Jayaramudu, Tippabattini; Raghavendra, Gownolla Malegowd; Varaprasad, Kokkarachedu; Sadiku, Rotimi; Ramam, Koduri; Raju, Konduru Mohana

    2013-06-01

    In this paper, we report the synthesis and characterization of Iota-Carrageenan based on a novel biodegradable silver nanocomposite hydrogels. The aim of study was to investigate whether these hydrogels have the potential to be used in bacterial inactivation applications. Biodegradable silver nanocomposite hydrogels were prepared by a green process using acrylamide (AM) with I-Carrageenan (IC). The silver nanoparticles were prepared as silver colloid by reducing AgNO3 with leaf extracts of Azadirachta indica (neem leaf) that (Ag(0)) formed the hydrogel network. The formation of biodegradable silver nanoparticles in the hydrogels was characterized using UV-vis spectroscopy, thermo gravimetrical analysis, X-ray diffractometry studies, scanning electron microscopy and transmission electron microscopy studies. In addition, swelling behavior and degradation properties were systematically investigated. Furthermore, the biodegradable silver nanoparticle composite hydrogels developed were tested for antibacterial activities. The antibacterial activity of the biodegradable silver nanocomposite hydrogels was studied by inhibition zone method against Bacillus and Escherichia coli, which suggested that the silver nanocomposite hydrogels developed were effective as potential candidates for antimicrobial applications. Therefore, the inorganic biodegradable hydrogels developed can be used effectively for biomedical application.

  1. Characterization of blend hydrogels based on plasticized starch/cellulose acetate/carboxymethyl cellulose synthesized by electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Senna, Magdy M.; Mostafa, Abo El-Khair B.; Mahdy, Sanna R.; El-Naggar, Abdel Wahab M.

    2016-11-01

    Blend hydrogels based on aqueous solutions of plasticized starch and different ratios of cellulose acetate (CA) and carboxymethyl cellulose (CMC) were prepared by electron beam irradiation (EB). The blends before and after EB irradiation were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The physico-chemical properties of blend hydrogels prepared by electron beam irradiation were improved compared to unirradiated blends.

  2. Non-coalescence of oppositely charged droplets in pH-sensitive emulsions

    PubMed Central

    Liu, Tingting; Seiffert, Sebastian; Thiele, Julian; Abate, Adam R.; Weitz, David A.; Richtering, Walter

    2012-01-01

    Like charges stabilize emulsions, whereas opposite charges break emulsions. This is the fundamental principle for many industrial and practical processes. Using micrometer-sized pH-sensitive polymeric hydrogel particles as emulsion stabilizers, we prepare emulsions that consist of oppositely charged droplets, which do not coalesce. We observe noncoalescence of oppositely charged droplets in bulk emulsification as well as in microfluidic devices, where oppositely charged droplets are forced to collide within channel junctions. The results demonstrate that electrostatic interactions between droplets do not determine their stability and reveal the unique pH-dependent properties of emulsions stabilized by soft microgel particles. The noncoalescence can be switched to coalescence by neutralizing the microgels, and the emulsion can be broken on demand. This unusual feature of the microgel-stabilized emulsions offers fascinating opportunities for future applications of these systems. PMID:22203968

  3. Biomineralized biomimetic organic/inorganic hybrid hydrogels based on hyaluronic acid and poloxamer.

    PubMed

    Huh, Hyun Wook; Zhao, Linlin; Kim, So Yeon

    2015-08-01

    A biomineralized hydrogel system containing hyaluronic acid (HA) and poloxamer composed of a poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO-PPO-PEO) block copolymer was developed as a biomimetic thermo-responsive injectable hydrogel system for bone regeneration. Using HA and poloxamer macromers with polymerizable residues, organic/inorganic HA/poloxamer hydrogels with various compositions were prepared and subjected to a biomineralization process to mimic the bone extracellular matrix. An increase in HA content within the hydrogels enhanced intermolecular chelation with calcium ions, leading to an increase in nucleation and growth of calcium phosphate in the hydrogels. After the biomineralization procedure, a crystalline formation was observed within and on the surface of the hydrogel. All of the HA/poloxamer hydrogel samples exhibited relatively high water content of greater than 90% at 25 °C, and the water content was influenced by the HA/poloxamer composition, biomineralization, and temperature. In particular, the HA/poloxamer hydrogel was injectable through a syringe without demonstrating appreciable macroscopic fracture at room temperature, whereas it was more opaque and adopted a more rigid structure as the temperature increased because of the increasing hydrophobicity of poloxamer. The enzymatic degradation behavior of the hydrogels depended on the concentration of hyaluronidase, HA/poloxamer composition, and biomineralization. The release kinetics of model drugs from HA/poloxamer hydrogels was primarily dependent on the drug loading content, water content, biomineralization of the hydrogels, and ionic properties of the drug. These results indicate that biomineralized HA/poloxamer hydrogel is a promising candidate material for a biomimetic hydrogel system that promotes bone tissue repair and regeneration via local delivery of drugs.

  4. Biomineralized biomimetic organic/inorganic hybrid hydrogels based on hyaluronic acid and poloxamer.

    PubMed

    Huh, Hyun Wook; Zhao, Linlin; Kim, So Yeon

    2015-08-01

    A biomineralized hydrogel system containing hyaluronic acid (HA) and poloxamer composed of a poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO-PPO-PEO) block copolymer was developed as a biomimetic thermo-responsive injectable hydrogel system for bone regeneration. Using HA and poloxamer macromers with polymerizable residues, organic/inorganic HA/poloxamer hydrogels with various compositions were prepared and subjected to a biomineralization process to mimic the bone extracellular matrix. An increase in HA content within the hydrogels enhanced intermolecular chelation with calcium ions, leading to an increase in nucleation and growth of calcium phosphate in the hydrogels. After the biomineralization procedure, a crystalline formation was observed within and on the surface of the hydrogel. All of the HA/poloxamer hydrogel samples exhibited relatively high water content of greater than 90% at 25 °C, and the water content was influenced by the HA/poloxamer composition, biomineralization, and temperature. In particular, the HA/poloxamer hydrogel was injectable through a syringe without demonstrating appreciable macroscopic fracture at room temperature, whereas it was more opaque and adopted a more rigid structure as the temperature increased because of the increasing hydrophobicity of poloxamer. The enzymatic degradation behavior of the hydrogels depended on the concentration of hyaluronidase, HA/poloxamer composition, and biomineralization. The release kinetics of model drugs from HA/poloxamer hydrogels was primarily dependent on the drug loading content, water content, biomineralization of the hydrogels, and ionic properties of the drug. These results indicate that biomineralized HA/poloxamer hydrogel is a promising candidate material for a biomimetic hydrogel system that promotes bone tissue repair and regeneration via local delivery of drugs. PMID:25933531

  5. Photoinduced Charge Transfer at Metal Oxide/Oxide Interfaces Prepared with Plasma Enhanced Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Kaur, Manpuneet

    LiNbO3 and ZnO have shown great potential for photochemical surface reactions and specific photocatalytic processes. However, the efficiency of LiNbO3 is limited due to recombination or back reactions and ZnO exhibits a chemical instability in a liquid cell. In this dissertation, both materials were coated with precise thickness of metal oxide layers to passivate the surfaces and to enhance their photocatalytic efficiency. LiNbO 3 was coated with plasma enhanced atomic layer deposited (PEALD) ZnO and Al2O3, and molecular beam deposited TiO2 and VO2. On the other hand, PEALD ZnO and single crystal ZnO were passivated with PEALD SiO2 and Al2O3. Metal oxide/LiNbO3 heterostructures were immersed in aqueous AgNO3 solutions and illuminated with ultraviolet (UV) light to form Ag nanoparticle patterns. Alternatively, Al2O3 and SiO2/ZnO heterostructures were immersed in K3PO 4 buffer solutions and studied for photoelectrochemical reactions. A fundamental aspect of the heterostructures is the band alignment and band bending, which was deduced from in situ photoemission measurements. This research has provided insight to three aspects of the heterostructures. First, the band alignment at the interface of metal oxides/LiNbO 3, and Al2O3 or SiO2/ZnO were used to explain the possible charge transfer processes and the direction of carrier flow in the heterostructures. Second, the effect of metal oxide coatings on the LiNbO3 with different internal carrier concentrations was related to the surface photochemical reactions. Third is the surface passivation and degradation mechanism of Al2O 3 and SiO2 on ZnO was established. The heterostructures were characterized after stability tests using atomic force microscopy (AFM), scanning electron microscopy (SEM), and cross-section transmission electron microscopy (TEM). The results indicate that limited thicknesses of ZnO or TiO2 on polarity patterned LiNbO3 (PPLN) enhances the Ag+ photoinduced reduction process. ZnO seems more efficient

  6. Covalently-crosslinked mucin biopolymer hydrogels for sustained drug delivery.

    PubMed

    Duffy, Connor V; David, Laurent; Crouzier, Thomas

    2015-07-01

    The sustained delivery of both hydrophobic and hydrophilic drugs from hydrogels has remained a challenge requiring the design and scalable production of complex multifunctional synthetic polymers. Here, we demonstrate that mucin glycoproteins, the gel-forming constituents of native mucus, are suitable for assembly into robust hydrogels capable of facilitating the sustained release of hydrophobic and hydrophilic drugs. Covalently-crosslinked mucin hydrogels were generated via exposure of methacrylated mucin to ultraviolet light in the presence of a free radical photoinitiator. The hydrogels exhibited an elastic modulus similar to that of soft mammalian tissue and were sensitive to proteolytic degradation by pronase. Paclitaxel, a hydrophobic anti-cancer drug, and polymyxin B, a positively-charged hydrophilic antibacterial drug, were retained in the hydrogels and released linearly with time over seven days. After four weeks of drug release, the hydrogels continued to release sufficient amounts of active paclitaxel to reduce HeLa cell viability and sufficient amounts of active polymyxin B to prevent bacterial proliferation. Along with previously-established anti-inflammatory, anti-viral, and hydrocarbon-solubilizing properties of mucin, the results of this study establish mucin as a readily-available, chemically-versatile, naturally-biocompatible alternative to complex multifunctional synthetic polymers as building blocks in the design of biomaterials for sustained drug delivery.

  7. Repairable, nanostructured biomimetic hydrogels

    NASA Astrophysics Data System (ADS)

    Firestone, M.; Brombosz, S.; Grubjesic, S.

    2013-03-01

    Proteins facilitate many key cellular processes, including signal recognition and energy transduction. The ability to harness this evolutionarily-optimized functionality could lead to the development of protein-based systems useful for advancing alternative energy storage and conversion. The future of protein-based, however, requires the development of materials that will stabilize, order and control the activity of the proteins. Recently we have developed a synthetic approach for the preparation of a durable biomimetic chemical hydrogel that can be reversibly swollen in water. The matrix has proven ideal for the stable encapsulation of both water- and membrane-soluble proteins. The material is composed of an aqueous dispersion of a diacrylate end-derivatized PEO-PPO-PEO macromer, a saturated phospholipid and a zwitterionic co-surfactant that self-assembles into a nanostructured physical gel at room temperature as determined by X-ray scattering. The addition of a water soluble PEGDA co-monomer and photoinitator does not alter the self-assembled structure and UV irradiation serves to crosslink the acrylate end groups on the macromer with the PEGDA forming a network within the aqueous domains as determined by FT-IR. More recently we have begun to incorporate reversible crosslinks employing Diels-Alder chemistry, allowing for the extraction and replacement of inactive proteins. The ability to replenish the materials with active, non-denatured forms of protein is an important step in advancing these materials for use in nanostructured devices This work was supported by the Office of Basic Energy Sciences, Division of Materials Sciences, USDoE under Contract No. DE-AC02-06CH11357.

  8. Camptothecine encapsulated composite drug delivery system for colorectal peritoneal carcinomatosis therapy: biodegradable microsphere in thermosensitive hydrogel.

    PubMed

    Liu, Lei; Wu, Qinjie; Ma, Xuelei; Xiong, Dake; Gong, Changyang; Qian, Zhiyong; Zhao, Xia; Wei, Yuquan

    2013-06-01

    In this work, we developed a biodegradable and injectable composite drug delivery system (DDS), camptothecine (CPT) loaded polymeric microsphere in thermosensitive hydrogel, for colorectal peritoneal carcinomatosis (CRPC) therapy. In our previous studies, we found that poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) copolymers with different molecular weight and PEG/PCL ratio could be administrated to form microsphere or thermosensitive hydrogel, respectively. Therefore, the composite DDS was composed of CPT loaded microsphere (CPT-MS) and thermosensitive hydrogel. CPT-MS was prepared by CPT and PCEC copolymer (Mn=31,600) using an oil-in-water emulsion solvent evaporation method. Besides, biodegradable and injectable thermosensitive PCEC hydrogel (Mn=3150) with lower sol-gel transition temperature at around body temperature was also prepared. The CPT-MS in thermosensitive hydrogel (CPT-MS/hydrogel) composite is a free-flowing sol at ambient temperature and instantly converts into a non-flowing gel at body temperature. Furthermore, cytotoxicity assay indicated that both microsphere and hydrogel were biocompatible with very low cytotoxicity. In vitro release profile demonstrated a significant difference between rapid release of free CPT and much slower and sustained release of CPT-MS/hydrogel. In addition, intraperitoneal administration of CPT-MS/hydrogel could effectively suppress growth and metastasis of CT26 peritoneal carcinomatosis in vivo, and prolonged the survival of tumor bearing mice. Compared with CPT-MS or free CPT, CPT-MS/hydrogel induced a stronger anti-tumor effect by increasing apoptosis of tumor cells and inhibiting microvessel density of tumor tissue. Besides, side effects of CPT were also alleviated in CPT-MS/hydrogel-treated mice. Thus, our results suggested that CPT-MS/hydrogel may have great potential applications in clinic.

  9. Multilayer microfluidic PEGDA hydrogels.

    PubMed

    Cuchiara, Michael P; Allen, Alicia C B; Chen, Theodore M; Miller, Jordan S; West, Jennifer L

    2010-07-01

    Development of robust 3D tissue analogs in vitro is limited by passive, diffusional mass transport. Perfused microfluidic tissue engineering scaffolds hold the promise to improve mass transport limitations and promote the development of complex, metabolically dense, and clinically relevant tissues. We report a simple and robust multilayer replica molding technique in which poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) diacrylate (PEGDA) are serially replica molded to develop microfluidic PEGDA hydrogel networks embedded within independently fabricated PDMS housings. We demonstrate the ability to control solute-scaffold effective diffusivity as a function of solute molecular weight and hydrogel concentration. Within cell laden microfluidic hydrogels, we demonstrate increased cellular viability in perfused hydrogel systems compared to static controls. We observed a significant increase in cell viability at all time points greater than zero at distances up to 1 mm from the perfused channel. Knowledge of spatiotemporal mass transport and cell viability gradients provides useful engineering design parameters necessary to maximize overall scaffold viability and metabolic density. This work has applications in the development of hydrogels as in vitro diagnostics and ultimately as regenerative medicine based therapeutics.

  10. Enhanced mechanical performance of biocompatible hemicelluloses-based hydrogel via chain extension.

    PubMed

    Qi, Xian-Ming; Chen, Ge-Gu; Gong, Xiao-Dong; Fu, Gen-Que; Niu, Ya-Shuai; Bian, Jing; Peng, Feng; Sun, Run-Cang

    2016-09-16

    Hemicelluloses are widely used to prepare gel materials because of their renewability, biodegradability, and biocompatibility. Here, molecular chain extension of hemicelluloses was obtained in a two-step process. Composite hydrogels were prepared via free radical graft copolymerization of crosslinked quaternized hemicelluloses (CQH) and acrylic acid (AA) in the presence of crosslinking agent N,N'-methylenebisacrylamide (MBA). This chain extension strategy significantly improved the mechanical performance of the resulting hydrogels. The crosslinking density, compression modulus, and swelling capacities of hydrogels were tuned by changing the AA/CQH and MBA/CQH contents. Moreover, the biocompatibility test suggests that the hemicelluloses-based hydrogels exhibited no toxicity to cells and allowed cell growth. Taken together, these properties demonstrated that the composite hydrogels have potential applications in the fields of water absorbents, cell culture, and other functional biomaterials.

  11. Enhanced mechanical performance of biocompatible hemicelluloses-based hydrogel via chain extension

    PubMed Central

    Qi, Xian-Ming; Chen, Ge-Gu; Gong, Xiao-Dong; Fu, Gen-Que; Niu, Ya-Shuai; Bian, Jing; Peng, Feng; Sun, Run-Cang

    2016-01-01

    Hemicelluloses are widely used to prepare gel materials because of their renewability, biodegradability, and biocompatibility. Here, molecular chain extension of hemicelluloses was obtained in a two-step process. Composite hydrogels were prepared via free radical graft copolymerization of crosslinked quaternized hemicelluloses (CQH) and acrylic acid (AA) in the presence of crosslinking agent N,N’-methylenebisacrylamide (MBA). This chain extension strategy significantly improved the mechanical performance of the resulting hydrogels. The crosslinking density, compression modulus, and swelling capacities of hydrogels were tuned by changing the AA/CQH and MBA/CQH contents. Moreover, the biocompatibility test suggests that the hemicelluloses-based hydrogels exhibited no toxicity to cells and allowed cell growth. Taken together, these properties demonstrated that the composite hydrogels have potential applications in the fields of water absorbents, cell culture, and other functional biomaterials. PMID:27634095

  12. Enhanced mechanical performance of biocompatible hemicelluloses-based hydrogel via chain extension.

    PubMed

    Qi, Xian-Ming; Chen, Ge-Gu; Gong, Xiao-Dong; Fu, Gen-Que; Niu, Ya-Shuai; Bian, Jing; Peng, Feng; Sun, Run-Cang

    2016-01-01

    Hemicelluloses are widely used to prepare gel materials because of their renewability, biodegradability, and biocompatibility. Here, molecular chain extension of hemicelluloses was obtained in a two-step process. Composite hydrogels were prepared via free radical graft copolymerization of crosslinked quaternized hemicelluloses (CQH) and acrylic acid (AA) in the presence of crosslinking agent N,N'-methylenebisacrylamide (MBA). This chain extension strategy significantly improved the mechanical performance of the resulting hydrogels. The crosslinking density, compression modulus, and swelling capacities of hydrogels were tuned by changing the AA/CQH and MBA/CQH contents. Moreover, the biocompatibility test suggests that the hemicelluloses-based hydrogels exhibited no toxicity to cells and allowed cell growth. Taken together, these properties demonstrated that the composite hydrogels have potential applications in the fields of water absorbents, cell culture, and other functional biomaterials. PMID:27634095

  13. Synthesis of Gold Nanoflowers Encapsulated with Poly(N-isopropylacrylamide-co-acrylic acid) Hydrogels.

    PubMed

    Bae, Saet-Byeol; Lee, Sang-Wha

    2015-10-01

    In this work, hydrogel-coated gold nanoflowers (AuNFs@hydrogel) were facilely prepared. First, gold nanoflowers (AuNFs) were synthesized by reducing gold acid with ascorbic acid in the presence of chitosan biopolymers, and the chitosan-mediated AuNFs were subsequently conjugated with oleic acid with carboxylate groups. Finally, the olefin-conjugated AuNFs were encapsulated with P(NIPAM-co-AAC) hydrogels via a radical polymerization reaction with co-monomer ratio of [NIPAM:AAc = 91:9 wt%]. The encapsulated hydrogels had a lower critical solution temperature (LCST) slightly above the physiological temperature and demonstrated a thermo-sensitive variation of particle size. The hydrogel-coated AuNFs can be utilized as a promising thermo-responsive drug delivery system with a unique optical property. As-prepared samples were characterized by DLS, SEM, TEM, UV-vis and Zeta potential meter. PMID:26726447

  14. Hydrogels in Regenerative Medicine

    PubMed Central

    Slaughter, Brandon V.; Khurshid, Shahana S.; Fisher, Omar Z.; Khademhosseini, Ali

    2015-01-01

    Hydrogels, due to their unique biocompatibility, flexible methods of synthesis, range of constituents, and desirable physical characteristics, have been the material of choice for many applications in regenerative medicine. They can serve as scaffolds that provide structural integrity to tissue constructs, control drug and protein delivery to tissues and cultures, and serve as adhesives or barriers between tissue and material surfaces. In this work, the properties of hydrogels that are important for tissue engineering applications and the inherent material design constraints and challenges are discussed. Recent research involving several different hydrogels polymerized from a variety of synthetic and natural monomers using typical and novel synthetic methods are highlighted. Finally, special attention is given to the microfabrication techniques that are currently resulting in important advances in the field. PMID:20882499

  15. Starch nanocrystals based hydrogel: Construction, characterizations and transdermal application.

    PubMed

    Bakrudeen, Haja Bava; Sudarvizhi, C; Reddy, B S R

    2016-11-01

    Bio-based nanocomposites were prepared using starch nanocrystals obtained by acid hydrolysis of native starches using different acid sources. In recent times, focuses on starch nanocrystals (SNCs) have been increasing in number of research works dedicated to the development of bio-nanocomposites by blending with different biopolymeric matrices. The work mainly deals with the preparation of starch nanocrystals using different native starches by acid hydrolysis using hydrochloric acid and trifluroacetic acid. The as-prepared starch nanocrystals are having high crystallinity and more platelet morphologies, and used as a drug carrying filler material in the hydrogel formulations with the care of different polymer matrices. The condensed work also concentrates on the dispersion of antiviral drug in the hydrogels, which are applied onto biocompatible bio-membrane to be formulating a complete transdermal patch. The acid hydrolysed starch nanocrystals were thoroughly characterized using TEM, SEM, particle size analysis and zeta potential. Their thermal stability and the crystalline properties were also characterized using TG-DSC and XRD respectively. The physiochemical interaction and compatibility between the drug and the SNCs filler in the polymeric hydrogels were evaluated using FT-IR analysis. The formulated hydrogels were subjected to evaluation of in vitro permeation studies using Franz diffusion studies. The in vitro study was indicated substantial guarantee for the fabrication of drug dispersed in polymeric hydrogels using SNCs as filler matrices for a successful transdermal drug delivery. PMID:27524091

  16. Sulfiding of hydrogel derived catalysts

    SciTech Connect

    Kemp, R.A.

    1991-11-05

    This patent describes a process for hydrotreating hydrocarbon feeds. It comprises contacting the feeds at a temperature in the range of from about 400{degrees} F. to about 850{degrees} F. and a pressure in the range of from about 400 psig to about 2500 psig with a catalyst having improved desulfurization activity prepared by incorporating an element selected from the group consisting of nickel, cobalt and mixtures thereof, and a heavy metal selected from the group consisting of molybdenum, tungsten and mixtures thereof, into an alumina hydrogel containing a phosphorous-containing compound, and sulfiding the catalyst with a gaseous sulfur compound at a temperature of at least about 900{degrees} F. for at least one hour.

  17. Improving the stability of chitosan-gelatin-based hydrogels for cell delivery using transglutaminase and controlled release of doxycycline.

    PubMed

    Tormos, Christian J; Abraham, Carol; Madihally, Sundararajan V

    2015-12-01

    Although local cell delivery is an option to repair tissues, particularly using chitosan-based hydrogels, significant attrition of injected cells prior to engraftment has been a problem. To address this problem, we explored the possibility of stabilizing the chitosan-gelatin (CG) injectable hydrogels using (1) controlled release of doxycycline (DOX) to prevent premature degradation due to increased gelatinase activity (MMP-2 and MMP-9), and (2) transglutaminase (TG) to in situ cross-link gelatin to improve the mechanical stability. We prepared DOX-loaded PLGA nanoparticles, loaded into the CG hydrogels, measured DOX release for 5 days, and modeled using a single-compartmental assumption. Next, we assessed the influence of TG and DOX on hydrogel compression properties by incubating hydrogels for 7 days in PBS. We evaluated the effect of these changes on retention of fibroblasts and alterations in MMP-2/MMP-9 activity by seeding 500,000 fibroblasts for 5 days. These results showed that 90 % of DOX released from cross-linked CG hydrogels after 4 days, unlike CG hydrogels where 90 % of DOX was released within the first day. Addition of TG enhanced the CG hydrogel stability significantly. More than 60 % of seeded fibroblasts were recovered from the CG-TG hydrogels at day 5, unlike 40 % recovered from CG-hydrogels. Inhibition of MMP-2/MMP-9 were observed. In summary, controlled release of DOX from CG hydrogels cross-linked with TG shows a significant potential as a carrier for cell delivery.

  18. Enhanced loading efficiency and sustained release of doxorubicin from hyaluronic acid/graphene oxide composite hydrogels by a mussel-inspired catecholamine.

    PubMed

    Byun, Eunkyoung; Lee, Haeshin

    2014-10-01

    Hydrogels have been widely investigated as depots and carriers for drug delivery. For example, hydrogels have been successfully used to encapsulate a variety of pharmaceuticals, such as peptides and proteins. Recently, carbon material/hydrogel hybrid systems have been of interest as new hydrogel systems because of the attractiveness of structural reinforcement for biomedical applications. In particular, graphene and graphene oxide (GO) have been recognized as novel biomaterials with unique physical, electrical, and thermal properties. Among the various applications of these materials, many research groups are intensively exploring the biomedical applications of graphene and GO. In this study, we propose a new role for GO in hybrid hydrogels, with the inclusion of GO in the gel network resulting in a nearly 90% enhancement in the loading of small, hydrophobic drugs (e.g., doxorubicin, Dox) compared to the hydrogel without encapsulated GO. The hydrogels were prepared from hyaluronic acid (HA), with a mussel-inspired crosslinking chemistry used to prepare the HA hydrogels. Dox was then loaded into the hydrogels. The HA/GO composite hydrogel not only enhanced the loading amount but also exhibited long-lasting anticancer activity over 10 days. We believe that these graphene oxide-containing composite hydrogels can solve one of the challenges in the application of hydrogels by improving the loading efficiency of small-molecule drugs. PMID:25942800

  19. A novel injectable temperature-sensitive zinc doped chitosan/β-glycerophosphate hydrogel for bone tissue engineering.

    PubMed

    Niranjan, Ramesh; Koushik, Chandru; Saravanan, Sekaran; Moorthi, Ambigapathi; Vairamani, Mariappanadar; Selvamurugan, Nagarajan

    2013-03-01

    Hydrogels are hydrophilic polymers that have a wide range of biomedical applications including bone tissue engineering. In this study we report preparation and characterization of a thermosensitive hydrogel (Zn-CS/β-GP) containing zinc (Zn), chitosan (CS) and beta-glycerophosphate (β-GP) for bone tissue engineering. The prepared hydrogel exhibited a liquid state at room temperature and turned into a gel at body temperature. The hydrogel was characterized by SEM, EDX, XRD, FT-IR and swelling studies. The hydrogel enhanced antibacterial activity and promoted osteoblast differentiation. Thus, we suggest that the Zn-CS/β-GP hydrogel could have potential impact as an injectable in situ forming scaffold for bone tissue engineering applications.

  20. Preparation and physical properties of nanoaggregates composed of charge-transfer complexes containing butadiyne derivatives with tetrathiafulvalene moieties

    NASA Astrophysics Data System (ADS)

    Imai, Masato; Tatewaki, Yoko; Okada, Shuji

    2014-01-01

    Nanoaggregates of three butadiyne derivatives, i.e., butadiyne derivatives with one tetrathiafulvalene (TTF) moiety at one end (BUT1), two TTF moieties at both ends (BUT2), and one TTF moiety directly bound to the butadiyne group (TBU), and their charge-transfer (CT) complexes with 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane (F2TCNQ) were prepared by the reprecipitation method. The nanoaggregate sizes of BUT1, BUT2, and TBU were about 80-200 nm and those of the CT complexes were reduced to about 100 nm. Upon UV irradiation, nanoaggregates of BUT1 showed regular 1,4-addition polymerization in the solid state while those of BUT2 and TBU polymerized in an irregular manner. However, solid-state polymerization of their CT complexes was not confirmed and decomposition of the complexes was observed. From the X-ray study, the crystallinity of the nanoaggregates was found to degrade in general, compared with that of the corresponding bulk crystals. Interestingly, nanoaggregates of BUT1-F2TCNQ and BUT2-F2TCNQ complexes were found to have conductivities of more than 10-6 S/cm, although their bulk crystals did not show measurable conductivities.

  1. Oxidatively Responsive Chain Extension to Entangle Engineered Protein Hydrogels.

    PubMed

    Tang, Shengchang; Glassman, Matthew J; Li, Shuaili; Socrate, Simona; Olsen, Bradley D

    2014-01-28

    Engineering artificial protein hydrogels for medical applications requires precise control over their mechanical properties, including stiffness, toughness, extensibility and stability in the physiological environment. Here we demonstrate topological entanglement as an effective strategy to robustly increase the mechanical tunability of a transient hydrogel network based on coiled-coil interactions. Chain extension and entanglement are achieved by coupling the cysteine residues near the N- and C- termini, and the resulting chain distribution is found to agree with the Jacobson-Stockmayer theory. By exploiting the reversible nature of the disulfide bonds, the entanglement effect can be switched on and off by redox stimuli. With the presence of entanglements, hydrogels exhibit a 7.2-fold enhanced creep resistance and a suppressed erosion rate by a factor of 5.8, making the gels more mechanically stable in a physiologically relevant open system. While hardly affecting material stiffness (only resulting in a 1.5-fold increase in the plateau modulus), the entanglements remarkably lead to hydrogels with a toughness of 65,000 J m(-3) and extensibility to approximately 3,000% engineering strain, which enables the preparation of tough yet soft tissue simulants. This improvement in mechanical properties resembles that from double-network hydrogels, but is achieved with the use of a single associating network and topological entanglement. Therefore, redox-triggered chain entanglement offers an effective approach for constructing mechanically enhanced and responsive injectable hydrogels.

  2. Hydrogels for the Repair of Articular Cartilage Defects

    PubMed Central

    Maher, Suzanne A.; Lowman, Anthony M.

    2011-01-01

    The repair of articular cartilage defects remains a significant challenge in orthopedic medicine. Hydrogels, three-dimensional polymer networks swollen in water, offer a unique opportunity to generate a functional cartilage substitute. Hydrogels can exhibit similar mechanical, swelling, and lubricating behavior to articular cartilage, and promote the chondrogenic phenotype by encapsulated cells. Hydrogels have been prepared from naturally derived and synthetic polymers, as cell-free implants and as tissue engineering scaffolds, and with controlled degradation profiles and release of stimulatory growth factors. Using hydrogels, cartilage tissue has been engineered in vitro that has similar mechanical properties to native cartilage. This review summarizes the advancements that have been made in determining the potential of hydrogels to replace damaged cartilage or support new tissue formation as a function of specific design parameters, such as the type of polymer, degradation profile, mechanical properties and loading regimen, source of cells, cell-seeding density, controlled release of growth factors, and strategies to cause integration with surrounding tissue. Some key challenges for clinical translation remain, including limited information on the mechanical properties of hydrogel implants or engineered tissue that are necessary to restore joint function, and the lack of emphasis on the ability of an implant to integrate in a stable way with the surrounding tissue. Future studies should address the factors that affect these issues, while using clinically relevant cell sources and rigorous models of repair. PMID:21510824

  3. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    SciTech Connect

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-25

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  4. Recent advances in clay mineral-containing nanocomposite hydrogels.

    PubMed

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications. PMID:26435008

  5. Recent advances in clay mineral-containing nanocomposite hydrogels.

    PubMed

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

  6. Dynamic mechanical and swelling properties of maleated hyaluronic acid hydrogels.

    PubMed

    Lin, Hai; Liu, Jun; Zhang, Kai; Fan, Yujiang; Zhang, Xingdong

    2015-06-01

    A series of maleated hyaluronan (MaHA) are developed by modification with maleic anhydride. The degrees of substitution (DS) of MaHA vary between 7% and 75%. The DS of MaHA is both higher and wider than methacrylated HA derivatives (MeHA) reported in the literature. MaHA hydrogels are then prepared by photopolymerization and their dynamic mechanical and swelling properties of the hydrogels are investigated. The results showed that MaHA hydrogels with moderate DS (25%, 50% and 65%) have higher storage modulus and lower equilibrium swelling ratios than those with either low or high DS (7%, 15% and 75%). Theoretical analyses also suggest a similar pattern among hydrogels with different DS. The results confirm that the increased cross-linking density enhances the strength of hydrogels. Meanwhile, the hydrophilicity of introduced groups during modification and the degree of incomplete crosslinking reaction might have negative impact on the mechanical and swelling properties of MaHA hydrogels.

  7. Radiation synthesis of superabsorbent CMC based hydrogels for agriculture applications

    NASA Astrophysics Data System (ADS)

    Raafat, Amany I.; Eid, Mona; El-Arnaouty, Magda B.

    2012-07-01

    A series of superabsorbent hydrogel based on carboxymethylcellulose (CMC) and polyvinylpyrrolidone (PVP) crosslinked with gamma irradiation have been proposed for agriculture application. The effect of preparation conditions such as feed solution composition and absorbed irradiation dose on the gelation and swelling degree was evaluated. The structure and the morphology of the superabsorbent CMC/PVP hydrogel were characterized using Fourier transform infrared spectroscopy technique (FTIR), and scanning electron microscope (SEM). Effect of ionic strength and cationic and anionic kinds on the swelling behavior of the obtained hydrogel was investigated. Urea as an agrochemical model was loaded onto the obtained hydrogel to provide nitrogen (N) nutrients. The water retention capability and the urea release behavior of the CMC/PVP hydrogels were investigated. It was found that, the obtained CMC/PVP hydrogels have good swelling degree that greatly affected by its composition and absorbed dose. The swelling was also extremely sensitive to the ionic strength and cationic kind. Owing to its considerable slow urea release, good water retention capacity, being economical, and environment-friendly, it might be useful for its application in agriculture field.

  8. Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications.

    PubMed

    Borzacchiello, Assunta; Russo, Luisa; Malle, Birgitte M; Schwach-Abdellaoui, Khadija; Ambrosio, Luigi

    2015-01-01

    Hyaluronic acid (HA) hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS) based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injectability, and network structural parameters. They exhibit a rheological behaviour typical of strong gels and show improved viscoelastic properties by increasing HA concentration and decreasing HA/DVS weight ratio. Furthermore, it was demonstrated that processes such as sterilization and extrusion through clinical needles do not imply significant alteration of viscoelastic properties. Both SANS and rheological tests indicated that the cross-links appear to compact the network, resulting in a reduction of the mesh size by increasing the cross-linker amount. In vitro degradation tests of the HA hydrogels demonstrated that these new hydrogels show a good stability against enzymatic degradation, which increases by increasing HA concentration and decreasing HA/DVS weight ratio. Finally, the hydrogels show a good biocompatibility confirmed by in vitro tests. PMID:26090451

  9. Automation of 3D cell culture using chemically defined hydrogels.

    PubMed

    Rimann, Markus; Angres, Brigitte; Patocchi-Tenzer, Isabel; Braum, Susanne; Graf-Hausner, Ursula

    2014-04-01

    Drug development relies on high-throughput screening involving cell-based assays. Most of the assays are still based on cells grown in monolayer rather than in three-dimensional (3D) formats, although cells behave more in vivo-like in 3D. To exemplify the adoption of 3D techniques in drug development, this project investigated the automation of a hydrogel-based 3D cell culture system using a liquid-handling robot. The hydrogel technology used offers high flexibility of gel design due to a modular composition of a polymer network and bioactive components. The cell inert degradation of the gel at the end of the culture period guaranteed the harmless isolation of live cells for further downstream processing. Human colon carcinoma cells HCT-116 were encapsulated and grown in these dextran-based hydrogels, thereby forming 3D multicellular spheroids. Viability and DNA content of the cells were shown to be similar in automated and manually produced hydrogels. Furthermore, cell treatment with toxic Taxol concentrations (100 nM) had the same effect on HCT-116 cell viability in manually and automated hydrogel preparations. Finally, a fully automated dose-response curve with the reference compound Taxol showed the potential of this hydrogel-based 3D cell culture system in advanced drug development.

  10. Interfacial thiol-ene photoclick reactions for forming multilayer hydrogels.

    PubMed

    Shih, Han; Fraser, Andrew K; Lin, Chien-Chi

    2013-03-13

    Interfacial visible light-mediated thiol-ene photoclick reactions were developed for preparing step-growth hydrogels with multilayer structures. The effect of a noncleavage type photoinitiator eosin-Y on visible-light-mediated thiol-ene photopolymerization was first characterized using in situ photorheometry, gel fraction, and equilibrium swelling ratio. Next, spectrophotometric properties of eosin-Y in the presence of various relevant macromer species were evaluated using ultraviolet-visible light (UV-vis) spectrometry. It was determined that eosin-Y was able to reinitiate the thiol-ene photoclick reaction, even after light exposure. Because of its small molecular weight, most eosin-Y molecules readily leached out from the hydrogels. The diffusion of residual eosin-Y from preformed hydrogels was exploited for fabricating multilayer step-growth hydrogels. Interfacial hydrogel coating was formed via the same visible-light-mediated gelation mechanism without adding fresh initiator. The thickness of the thiol-ene gel coating could be easily controlled by adjusting visible light exposure time, eosin-Y concentration initially loaded in the core gel, or macromer concentration in the coating solution. The major benefits of this interfacial thiol-ene coating system include its simplicity and cytocompatibility. The formation of thiol-ene hydrogels and coatings neither requires nor generates any cytotoxic components. This new gelation chemistry may have great utilities in controlled release of multiple sensitive growth factors and encapsulation of multiple cell types for tissue regeneration. PMID:23384151

  11. Oxidatively Responsive Chain Extension to Entangle Engineered Protein Hydrogels

    PubMed Central

    Tang, Shengchang; Glassman, Matthew J.; Li, Shuaili; Socrate, Simona; Olsen, Bradley D.

    2014-01-01

    Engineering artificial protein hydrogels for medical applications requires precise control over their mechanical properties, including stiffness, toughness, extensibility and stability in the physiological environment. Here we demonstrate topological entanglement as an effective strategy to robustly increase the mechanical tunability of a transient hydrogel network based on coiled-coil interactions. Chain extension and entanglement are achieved by coupling the cysteine residues near the N- and C- termini, and the resulting chain distribution is found to agree with the Jacobson-Stockmayer theory. By exploiting the reversible nature of the disulfide bonds, the entanglement effect can be switched on and off by redox stimuli. With the presence of entanglements, hydrogels exhibit a 7.2-fold enhanced creep resistance and a suppressed erosion rate by a factor of 5.8, making the gels more mechanically stable in a physiologically relevant open system. While hardly affecting material stiffness (only resulting in a 1.5-fold increase in the plateau modulus), the entanglements remarkably lead to hydrogels with a toughness of 65,000 J m-3 and extensibility to approximately 3,000% engineering strain, which enables the preparation of tough yet soft tissue simulants. This improvement in mechanical properties resembles that from double-network hydrogels, but is achieved with the use of a single associating network and topological entanglement. Therefore, redox-triggered chain entanglement offers an effective approach for constructing mechanically enhanced and responsive injectable hydrogels. PMID:24910474

  12. Ocular injectable formulation assessment for oxidized dextran-based hydrogels.

    PubMed

    Maia, João; Ribeiro, Maximiano P; Ventura, Carla; Carvalho, Rui A; Correia, Ilídio J; Gil, Maria H

    2009-07-01

    Initiator-free injectable hydrogels are very interesting for drug and/or cell delivery applications, since they can be administered in a minimally invasive way, and avoid the use of potentially harmful chemical initiators. In the current work, oxidized dextran crosslinked with adipic acid dihydrazide hydrogels were further characterized and tuned to produce formulations, with the aim of producing an injectable formulation for the possible treatment of posterior eye diseases. The gelation rate and the hydrogel dissolution profile were shown to be dependent on the balance between the degree of dextran oxidation, and the concentration of both components. For the in vitro studies, rabbit corneal endothelial cells were seeded on the hydrogels to assess cytotoxicity. Hydrogels prepared with low oxidized dextrans were able to promote cell adhesion and proliferation to confluence in just 24h, while more highly oxidized samples promoted cell adhesion and proliferation, but without achieving confluence. Cell viability studies were performed using MTS assays to verify the non-cytotoxicity of hydrogels and their degradation byproducts, rendering these formulations attractive for further in vivo studies. PMID:19286432

  13. Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications

    PubMed Central

    Borzacchiello, Assunta; Russo, Luisa; Malle, Birgitte M.; Schwach-Abdellaoui, Khadija; Ambrosio, Luigi

    2015-01-01

    Hyaluronic acid (HA) hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS) based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injectability, and network structural parameters. They exhibit a rheological behaviour typical of strong gels and show improved viscoelastic properties by increasing HA concentration and decreasing HA/DVS weight ratio. Furthermore, it was demonstrated that processes such as sterilization and extrusion through clinical needles do not imply significant alteration of viscoelastic properties. Both SANS and rheological tests indicated that the cross-links appear to compact the network, resulting in a reduction of the mesh size by increasing the cross-linker amount. In vitro degradation tests of the HA hydrogels demonstrated that these new hydrogels show a good stability against enzymatic degradation, which increases by increasing HA concentration and decreasing HA/DVS weight ratio. Finally, the hydrogels show a good biocompatibility confirmed by in vitro tests. PMID:26090451

  14. Interfacial thiol-ene photoclick reactions for forming multilayer hydrogels.

    PubMed

    Shih, Han; Fraser, Andrew K; Lin, Chien-Chi

    2013-03-13

    Interfacial visible light-mediated thiol-ene photoclick reactions were developed for preparing step-growth hydrogels with multilayer structures. The effect of a noncleavage type photoinitiator eosin-Y on visible-light-mediated thiol-ene photopolymerization was first characterized using in situ photorheometry, gel fraction, and equilibrium swelling ratio. Next, spectrophotometric properties of eosin-Y in the presence of various relevant macromer species were evaluated using ultraviolet-visible light (UV-vis) spectrometry. It was determined that eosin-Y was able to reinitiate the thiol-ene photoclick reaction, even after light exposure. Because of its small molecular weight, most eosin-Y molecules readily leached out from the hydrogels. The diffusion of residual eosin-Y from preformed hydrogels was exploited for fabricating multilayer step-growth hydrogels. Interfacial hydrogel coating was formed via the same visible-light-mediated gelation mechanism without adding fresh initiator. The thickness of the thiol-ene gel coating could be easily controlled by adjusting visible light exposure time, eosin-Y concentration initially loaded in the core gel, or macromer concentration in the coating solution. The major benefits of this interfacial thiol-ene coating system include its simplicity and cytocompatibility. The formation of thiol-ene hydrogels and coatings neither requires nor generates any cytotoxic components. This new gelation chemistry may have great utilities in controlled release of multiple sensitive growth factors and encapsulation of multiple cell types for tissue regeneration.

  15. Adhesion in hydrogel contacts

    NASA Astrophysics Data System (ADS)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  16. Hydrogel-elastomer composite biomaterials: 2. Effects of aging methacrylated gelatin solutions on the preparation and physical properties of interpenetrating polymer networks.

    PubMed

    Peng, Henry T; Mok, Michelle; Martineau, Lucie; Shek, Pang N

    2007-06-01

    This study was conducted to understand the effects of aging methacrylated gelatin solutions on the properties of gelatin-HydroThane Interpenetrating Polymer Network (IPN) films. The latter were prepared from methacrylated gelatin solutions that were either freshly made or stored at different concentrations and temperatures for various periods. The morphology, swelling stability and mechanical properties of the IPNs were then accordingly characterized. The IPNs prepared with aged solutions showed a reduced phase separation; changed from a network-like structure to a continuous phase structure; and demonstrated higher swelling stabilities and higher elasticity under optimal aging conditions, compared to the IPN prepared with a fresh methacrylated gelatin solution. An increase in viscosity and a change in phase transition of aged methacrylated gelatin solutions were also observed, presumably due to the physical structuring of methacrylated gelatin chains (e.g., by the formation of a helix structure), thus altering the resulting IPN characteristics. A better understanding of the effects of aging methacrylated gelatin solution on the formation and properties of gelatin-HydroThane IPNs should enable us to further develop our composite biomaterials for different dressing applications.

  17. Sustained-release hydrogels of topotecan for retinoblastoma.

    PubMed

    Taich, Paula; Moretton, Marcela A; Del Sole, María Jose; Winter, Ursula; Bernabeu, Ezequiel; Croxatto, Juan O; Oppezzo, Javier; Williams, Gustavo; Chantada, Guillermo L; Chiappetta, Diego A; Schaiquevich, Paula

    2016-10-01

    Treatment of retinoblastoma, the most common primary ocular malignancy in children, has greatly improved over the last decade. Still, new devices for chemotherapy are needed to achieve better tumor control. The aim of this project was to develop an ocular drug delivery system for topotecan (TPT) loaded in biocompatible hydrogels of poly(ε-caprolactone)-poly(ethyleneglycol)-poly(ε-caprolactone) block copolymers (PCL-PEG-PCL) for sustained TPT release in the vitreous humor. Hydrogels were prepared from TPT and synthesized PCL-PEG-PCL copolymers. Rheological properties and in vitro and in vivo TPT release were studied. Hydrogel cytotoxicity was evaluated in retinoblastoma cells as a surrogate for efficacy and TPT vitreous pharmacokinetics and systemic as well as ocular toxicity were evaluated in rabbits. The pseudoplastic behavior of the hydrogels makes them suitable for intraocular administration. In vitro release profiles showed a sustained release of TPT from PCL-PEG-PCL up to 7days and drug loading did not affect the release pattern. Blank hydrogels did not affect retinoblastoma cell viability but 0.4% (w/w) TPT-loaded hydrogel was highly cytotoxic for at least 7days. After intravitreal injection, TPT vitreous concentrations were sustained above the pharmacologically active concentration. One month after injection, animals with blank or TPT-loaded hydrogels showed no systemic toxicity or retinal impairment on fundus examination, electroretinographic, and histopathological assessments. These novel TPT-hydrogels can deliver sustained concentrations of active drug into the vitreous with excellent biocompatibility in vivo and pronounced cytotoxic activity in retinoblastoma cells and may become an additional strategy for intraocular retinoblastoma treatment. PMID:27429296

  18. Sustained-release hydrogels of topotecan for retinoblastoma.

    PubMed

    Taich, Paula; Moretton, Marcela A; Del Sole, María Jose; Winter, Ursula; Bernabeu, Ezequiel; Croxatto, Juan O; Oppezzo, Javier; Williams, Gustavo; Chantada, Guillermo L; Chiappetta, Diego A; Schaiquevich, Paula

    2016-10-01

    Treatment of retinoblastoma, the most common primary ocular malignancy in children, has greatly improved over the last decade. Still, new devices for chemotherapy are needed to achieve better tumor control. The aim of this project was to develop an ocular drug delivery system for topotecan (TPT) loaded in biocompatible hydrogels of poly(ε-caprolactone)-poly(ethyleneglycol)-poly(ε-caprolactone) block copolymers (PCL-PEG-PCL) for sustained TPT release in the vitreous humor. Hydrogels were prepared from TPT and synthesized PCL-PEG-PCL copolymers. Rheological properties and in vitro and in vivo TPT release were studied. Hydrogel cytotoxicity was evaluated in retinoblastoma cells as a surrogate for efficacy and TPT vitreous pharmacokinetics and systemic as well as ocular toxicity were evaluated in rabbits. The pseudoplastic behavior of the hydrogels makes them suitable for intraocular administration. In vitro release profiles showed a sustained release of TPT from PCL-PEG-PCL up to 7days and drug loading did not affect the release pattern. Blank hydrogels did not affect retinoblastoma cell viability but 0.4% (w/w) TPT-loaded hydrogel was highly cytotoxic for at least 7days. After intravitreal injection, TPT vitreous concentrations were sustained above the pharmacologically active concentration. One month after injection, animals with blank or TPT-loaded hydrogels showed no systemic toxicity or retinal impairment on fundus examination, electroretinographic, and histopathological assessments. These novel TPT-hydrogels can deliver sustained concentrations of active drug into the vitreous with excellent biocompatibility in vivo and pronounced cytotoxic activity in retinoblastoma cells and may become an additional strategy for intraocular retinoblastoma treatment.

  19. Horseradish peroxidase-catalysed in situ-forming hydrogels for tissue-engineering applications.

    PubMed

    Bae, Jin Woo; Choi, Jong Hoon; Lee, Yunki; Park, Ki Dong

    2015-11-01

    In situ-forming hydrogels are an attractive class of implantable biomaterials that are used for biomedical applications. These injectable hydrogels are versatile and provide a convenient platform for delivering cells and drugs via minimally invasive surgery. Although several crosslinking methods for preparing in situ forming hydrogels have been developed over the past two decades, most hydrogels are not sufficiently versatile for use in a wide variety of tissue-engineering applications. In recent years, enzyme-catalysed crosslinking approaches have been emerged as a new approach for developing in situ-forming hydrogels. In particular, the horseradish peroxidase (HRP)-catalysed crosslinking approach has received increasing interest, due to its highly improved and tunable capacity to obtain hydrogels with desirable properties. The HRP-catalysed crosslinking reaction immediately occurs upon mixing phenol-rich polymers with HRP and hydrogen peroxide (H2O2) in aqueous media. Based on this unique gel-forming feature, recent studies have shown that various properties of formed hydrogels, such as gelation time, stiffness and degradation rate, can be easily manipulated by varying the concentrations of HRP and H2O2. In this review, we outline the versatile properties of HRP-catalysed in situ-forming hydrogels, with a brief introduction to the crosslinking mechanisms involved. In addition, the recent biomedical applications of HRP-catalysed in situ-forming hydrogels for tissue regeneration are described. PMID:24916126

  20. Functional elastic hydrogel as recyclable membrane for the adsorption and degradation of methylene blue.

    PubMed

    Bao, Song; Wu, Dongbei; Wang, Qigang; Su, Teng

    2014-01-01

    Developing the application of high-strength hydrogels has gained much attention in the fields of medical, pharmacy, and pollutant removal due to their versatility and stimulus-responsive properties. In this presentation, a high-strength freestanding elastic hydrogel membrane was constructed by clay nanosheets, N, N-dimethylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid for adsorption of methylene blue and heavy metal ions. The maximum values of elongation and Young's modulus for 0.5% AMPSNa hydrogel were 1901% and 949.4 kPa, respectively, much higher than those of traditional hydrogels. The adsorptions were confirmed to follow pseudo-second kinetic equation and Langmuir isotherm model fits the data well. The maximum adsorption capacity of hydrogel towards methylene blue was 434.8 mg g(-1). The hydrogel also exhibited higher separation selectivity to Pb(2+) than Cu(2+). The methylene blue adsorbed onto the hydrogel membrane can be photocatalytically degraded by Fenton agent and the hydrogel membrane could be recycled at least five times without obvious loss in mechanical properties. In conclusion, this presentation demonstrates a convenient strategy to prepare tough and elastic clay nanocomposite hydrogel, which can not only be applied as recyclable membrane for the photocatalytic degradation of organic dye, but also for the recovery of valuables. PMID:24586396

  1. Functional elastic hydrogel as recyclable membrane for the adsorption and degradation of methylene blue.

    PubMed

    Bao, Song; Wu, Dongbei; Wang, Qigang; Su, Teng

    2014-01-01

    Developing the application of high-strength hydrogels has gained much attention in the fields of medical, pharmacy, and pollutant removal due to their versatility and stimulus-responsive properties. In this presentation, a high-strength freestanding elastic hydrogel membrane was constructed by clay nanosheets, N, N-dimethylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid for adsorption of methylene blue and heavy metal ions. The maximum values of elongation and Young's modulus for 0.5% AMPSNa hydrogel were 1901% and 949.4 kPa, respectively, much higher than those of traditional hydrogels. The adsorptions were confirmed to follow pseudo-second kinetic equation and Langmuir isotherm model fits the data well. The maximum adsorption capacity of hydrogel towards methylene blue was 434.8 mg g(-1). The hydrogel also exhibited higher separation selectivity to Pb(2+) than Cu(2+). The methylene blue adsorbed onto the hydrogel membrane can be photocatalytically degraded by Fenton agent and the hydrogel membrane could be recycled at least five times without obvious loss in mechanical properties. In conclusion, this presentation demonstrates a convenient strategy to prepare tough and elastic clay nanocomposite hydrogel, which can not only be applied as recyclable membrane for the photocatalytic degradation of organic dye, but also for the recovery of valuables.

  2. Superabsorbent polysaccharide hydrogels based on pullulan derivate as antibacterial release wound dressing.

    PubMed

    Li, Huanan; Yang, Jing; Hu, Xiaona; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

    2011-07-01

    To accomplish ideal wound dressing, hydrogels based on a natural polysaccharide, pullulan were synthesized by chemical cross-linking. The tensile strengths of the hydrogel films (1 mm thick) were determined to range from 0.663 to 1.097 MPa in proportion to cross-linking degrees and water contents. The swelling study of the hydrogels in water showed remarkable water absorption property with swelling ratio up to 4000%, which provided the hydrogel with quick hemostatic ability and prevent the wound bed from accumulation of exudates. The water vapor transmission rate and water retention of the hydrogels were found to be in the range of 2213-3498 g/m²/day and 34.74-45.81% (after 6 days), indicating that the hydrogel can maintain a moist environment over wound bed, which could prevent the dehydration of the wound bed and prevent the scab formation. Biocompatibility test revealed that the hydrogels were not cytotoxic. The hydrogel could load antimicrobial agents and effectively suppress bacterial proliferation to protect the wound from bacterial invasion. These results suggest that the pullulan hydrogels prepared in this study may have high potential as new ideal wound-dressing materials.

  3. Effect of discarded keratin-based biocomposite hydrogels on the wound healing process in vivo.

    PubMed

    Park, Mira; Shin, Hye Kyoung; Kim, Byoung-Suhk; Kim, Myung Jin; Kim, In-Shik; Park, Byung-Yong; Kim, Hak-Yong

    2015-10-01

    Biocompatible keratin-based hydrogels prepared by electron beam irradiation (EBI) were examined in wound healing. As the EBI dose increased to 60 kGy, the tensile strength of the hydrogels increased, while the percentage of elongation of the hydrogels decreased. After 7 days, the dehydrated wool-based hydrogels show the highest mechanical properties (the % elongation of 1341 and the tensile strength of 6030 g/cm(2) at an EBI dose of 30 kGy). Excision wound models were used to evaluate the effects of human hair-based hydrogels and wool-based hydrogels on various phases of healing. On post-wounding days 7 and 14, wounds treated with either human hair-based or wool-based hydrogels were greatly reduced in size compared to wounds that received other treatments, although the hydrocolloid wound dressing-treated wound also showed a pronounced reduction in size compared to an open wound as measured by a histological assay. On the 14th postoperative day, the cellular appearances were similar in the hydrocolloid wound dressing and wool-based hydrogel-treated wounds, and collagen fibers were substituted with fibroblasts and mixed with fibroblasts in the dermis. Furthermore, the wound treated with a human hair-based hydrogel showed almost complete epithelial regeneration, with the maturation of immature connective tissue and hair follicles and formation of a sebaceous gland.

  4. The physical and chemical properties of the polyvinylalcohol/polyvinylpyrrolidone/hydroxyapatite composite hydrogel.

    PubMed

    Ma, Yahui; Bai, Tongchun; Wang, Fei

    2016-02-01

    A hydrogel of polyvinylalcohol (PVA)/polyvinylpyrrolidone (PVP)/hydroxyapatite (HA) was prepared by a repeated freezing and thawing technique. The effect of HA on the hydrogel was evaluated by comparing the physical and chemical properties of PVA/PVP/HA and PVA/PVP hydrogels. By using theoretical models, the information about the swelling kinetics and the dehydration kinetics have been obtained. From the analysis of structure, mechanical properties, and molecular interaction, the application of PVA/PVP/HA hydrogel as a biomaterial has been evaluated. Relative to PVA/PVP, the PVA/PVP/HA hydrogel is of denser network structure, lower water content, larger storage modulus, and higher dehydration activation energy. These results reveal that, as HA fills in the hydrogel, the molecular interaction is enhanced, the free space of network is compressed, and the diffusion activation energy of water is increased. In spite of its water content being decreased, it is still in the range of meeting the requirement of bio-application. When the hydrogel is subjected to external forces, the matrix will transfer the load to the HA powder, thus enhance the strength of the hydrogel. For application in bio-materials, HA will still have osteoinductivity because its crystalline structure is not interrupted in PVA/PVP/HA hydrogel environment. PMID:26652452

  5. Injectable in situ forming xylitol-PEG-based hydrogels for cell encapsulation and delivery.

    PubMed

    Selvam, Shivaram; Pithapuram, Madhav V; Victor, Sunita P; Muthu, Jayabalan

    2015-02-01

    Injectable in situ crosslinking hydrogels offer unique advantages over conventional prefabricated hydrogel methodologies. Herein, we synthesize poly(xylitol-co-maleate-co-PEG) (pXMP) macromers and evaluate their performance as injectable cell carriers for tissue engineering applications. The designed pXMP elastomers were non-toxic and water-soluble with viscosity values permissible for subcutaneous injectable systems. pXMP-based hydrogels prepared via free radical polymerization with acrylic acid as crosslinker possessed high crosslink density and exhibited a broad range of compressive moduli that could match the natural mechanical environment of various native tissues. The hydrogels displayed controlled degradability and exhibited gradual increase in matrix porosity upon degradation. The hydrophobic hydrogel surfaces preferentially adsorbed albumin and promoted cell adhesion and growth in vitro. Actin staining on cells cultured on thin hydrogel films revealed subconfluent cell monolayers composed of strong, adherent cells. Furthermore, fabricated 3D pXMP cell-hydrogel constructs promoted cell survival and proliferation in vitro. Cumulatively, our results demonstrate that injectable xylitol-PEG-based hydrogels possess excellent physical characteristics and exhibit exceptional cytocompatibility in vitro. Consequently, they show great promise as injectable hydrogel systems for in situ tissue repair and regeneration.

  6. Horseradish peroxidase-catalysed in situ-forming hydrogels for tissue-engineering applications.

    PubMed

    Bae, Jin Woo; Choi, Jong Hoon; Lee, Yunki; Park, Ki Dong

    2015-11-01

    In situ-forming hydrogels are an attractive class of implantable biomaterials that are used for biomedical applications. These injectable hydrogels are versatile and provide a convenient platform for delivering cells and drugs via minimally invasive surgery. Although several crosslinking methods for preparing in situ forming hydrogels have been developed over the past two decades, most hydrogels are not sufficiently versatile for use in a wide variety of tissue-engineering applications. In recent years, enzyme-catalysed crosslinking approaches have been emerged as a new approach for developing in situ-forming hydrogels. In particular, the horseradish peroxidase (HRP)-catalysed crosslinking approach has received increasing interest, due to its highly improved and tunable capacity to obtain hydrogels with desirable properties. The HRP-catalysed crosslinking reaction immediately occurs upon mixing phenol-rich polymers with HRP and hydrogen peroxide (H2O2) in aqueous media. Based on this unique gel-forming feature, recent studies have shown that various properties of formed hydrogels, such as gelation time, stiffness and degradation rate, can be easily manipulated by varying the concentrations of HRP and H2O2. In this review, we outline the versatile properties of HRP-catalysed in situ-forming hydrogels, with a brief introduction to the crosslinking mechanisms involved. In addition, the recent biomedical applications of HRP-catalysed in situ-forming hydrogels for tissue regeneration are described.

  7. Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties.

    PubMed

    Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Silan, Coskun; Aktas, Nahit; Turk, Mustafa

    2016-01-01

    A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90°C for 2h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5°C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS(+) radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro.

  8. Superabsorbent polysaccharide hydrogels based on pullulan derivate as antibacterial release wound dressing.

    PubMed

    Li, Huanan; Yang, Jing; Hu, Xiaona; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

    2011-07-01

    To accomplish ideal wound dressing, hydrogels based on a natural polysaccharide, pullulan were synthesized by chemical cross-linking. The tensile strengths of the hydrogel films (1 mm thick) were determined to range from 0.663 to 1.097 MPa in proportion to cross-linking degrees and water contents. The swelling study of the hydrogels in water showed remarkable water absorption property with swelling ratio up to 4000%, which provided the hydrogel with quick hemostatic ability and prevent the wound bed from accumulation of exudates. The water vapor transmission rate and water retention of the hydrogels were found to be in the range of 2213-3498 g/m²/day and 34.74-45.81% (after 6 days), indicating that the hydrogel can maintain a moist environment over wound bed, which could prevent the dehydration of the wound bed and prevent the scab formation. Biocompatibility test revealed that the hydrogels were not cytotoxic. The hydrogel could load antimicrobial agents and effectively suppress bacterial proliferation to protect the wound from bacterial invasion. These results suggest that the pullulan hydrogels prepared in this study may have high potential as new ideal wound-dressing materials. PMID:21523902

  9. The physical and chemical properties of the polyvinylalcohol/polyvinylpyrrolidone/hydroxyapatite composite hydrogel.

    PubMed

    Ma, Yahui; Bai, Tongchun; Wang, Fei

    2016-02-01

    A hydrogel of polyvinylalcohol (PVA)/polyvinylpyrrolidone (PVP)/hydroxyapatite (HA) was prepared by a repeated freezing and thawing technique. The effect of HA on the hydrogel was evaluated by comparing the physical and chemical properties of PVA/PVP/HA and PVA/PVP hydrogels. By using theoretical models, the information about the swelling kinetics and the dehydration kinetics have been obtained. From the analysis of structure, mechanical properties, and molecular interaction, the application of PVA/PVP/HA hydrogel as a biomaterial has been evaluated. Relative to PVA/PVP, the PVA/PVP/HA hydrogel is of denser network structure, lower water content, larger storage modulus, and higher dehydration activation energy. These results reveal that, as HA fills in the hydrogel, the molecular interaction is enhanced, the free space of network is compressed, and the diffusion activation energy of water is increased. In spite of its water content being decreased, it is still in the range of meeting the requirement of bio-application. When the hydrogel is subjected to external forces, the matrix will transfer the load to the HA powder, thus enhance the strength of the hydrogel. For application in bio-materials, HA will still have osteoinductivity because its crystalline structure is not interrupted in PVA/PVP/HA hydrogel environment.

  10. Periodontal Tissue Regeneration Using Enzymatically Solidified Chitosan Hydrogels With or Without Cell Loading

    PubMed Central

    Yan, Xiang-Zhen; van den Beucken, Jeroen J.J.P.; Cai, Xinjie; Yu, Na; Jansen, John A.

    2015-01-01

    This study is aimed to evaluate the in vivo biocompatibility and periodontal regenerative potential of enzymatically solidified chitosan hydrogels with or without incorporated periodontal ligament cells (PDLCs). To this end, chitosan hydrogels, with (n=8; CHIT+CELL) or without (n=8; CHIT) fluorescently labeled PDLCs, were prepared and transplanted into rat intrabony periodontal defects; untreated defects were used as empty controls (n=8; EMPTY). After 4 weeks, maxillae were harvested, decalcified, and used for histological, histomorphometrical, and immunohistochemical assessments. The results showed that PDLCs remained viable upon encapsulation within chitosan hydrogels before transplantation. Histological analysis demonstrated that the chitosan hydrogels were largely degraded after 4 weeks of implantation, without any adverse reaction in the surrounding tissue. In terms of periodontal regeneration, alveolar bone height, alveolar bone area, and epithelial downgrowth were comparable for CHIT, CHIT+CELL, as well as EMPTY groups. In contrast, both CHIT and CHIT+CELL showed a significant increase in functional ligament length compared with EMPTY. From a cellular perspective, the contribution of chitosan hydrogel-incorporated cells to the periodontal regeneration could not be ascertained, as no signal from transplanted PDLCs could be detected at 4 weeks posttransplantation. The results demonstrated that enzymatically solidified chitosan hydrogels are highly biocompatible and biodegradable. Moreover, chitosan hydrogels without cell loading can improve periodontal regeneration in terms of functional ligament length, indicating the great potential of this hydrogel in clinical applications. Further work on the use of chitosan hydrogels as cell carriers is required. PMID:25345525

  11. Functional Elastic Hydrogel as Recyclable Membrane for the Adsorption and Degradation of Methylene Blue

    PubMed Central

    Bao, Song; Wu, Dongbei; Wang, Qigang; Su, Teng

    2014-01-01

    Developing the application of high-strength hydrogels has gained much attention in the fields of medical, pharmacy, and pollutant removal due to their versatility and stimulus-responsive properties. In this presentation, a high-strength freestanding elastic hydrogel membrane was constructed by clay nanosheets, N, N-dimethylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid for adsorption of methylene blue and heavy metal ions. The maximum values of elongation and Young’s modulus for 0.5% AMPSNa hydrogel were 1901% and 949.4 kPa, respectively, much higher than those of traditional hydrogels. The adsorptions were confirmed to follow pseudo-second kinetic equation and Langmuir isotherm model fits the data well. The maximum adsorption capacity of hydrogel towards methylene blue was 434.8 mg g−1. The hydrogel also exhibited higher separation selectivity to Pb2+ than Cu2+. The methylene blue adsorbed onto the hydrogel membrane can be photocatalytically degraded by Fenton agent and the hydrogel membrane could be recycled at least five times without obvious loss in mechanical properties. In conclusion, this presentation demonstrates a convenient strategy to prepare tough and elastic clay nanocomposite hydrogel, which can not only be applied as recyclable membrane for the photocatalytic degradation of organic dye, but also for the recovery of valuables. PMID:24586396

  12. Efficient charge-carrier extraction from Ag2S quantum dots prepared by the SILAR method for utilization of multiple exciton generation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoliang; Liu, Jianhua; Johansson, Erik M. J.

    2015-01-01

    The utilization of electron-hole pairs (EHPs) generated from multiple excitons in quantum dots (QDs) is of great interest toward efficient photovoltaic devices and other optoelectronic devices; however, extraction of charge carriers remains difficult. Herein, we extract photocharges from Ag2S QDs and investigate the dependence of the electric field on the extraction of charges from multiple exciton generation (MEG). Low toxic Ag2S QDs are directly grown on TiO2 mesoporous substrates by employing the successive ionic layer adsorption and reaction (SILAR) method. The contact between QDs is important for the initial charge separation after MEG and for the carrier transport, and the space between neighbor QDs decreases with more SILAR cycles, resulting in better charge extraction. At the optimal electric field for extraction of photocharges, the results suggest that the threshold energy (hνth) for MEG is 2.41Eg. The results reveal that Ag2S QD is a promising material for efficient extraction of charges from MEG and that QDs prepared by SILAR have an advantageous electrical contact facilitating charge separation and extraction.The utilization of electron-hole pairs (EHPs) generated from multiple excitons in quantum dots (QDs) is of great interest toward efficient photovoltaic devices and other optoelectronic devices; however, extraction of charge carriers remains difficult. Herein, we extract photocharges from Ag2S QDs and investigate the dependence of the electric field on the extraction of charges from multiple exciton generation (MEG). Low toxic Ag2S QDs are directly grown on TiO2 mesoporous substrates by employing the successive ionic layer adsorption and reaction (SILAR) method. The contact between QDs is important for the initial charge separation after MEG and for the carrier transport, and the space between neighbor QDs decreases with more SILAR cycles, resulting in better charge extraction. At the optimal electric field for extraction of photocharges, the

  13. Design of biomimetic super-lubricants by hydrogel-biopolymer aggregates

    NASA Astrophysics Data System (ADS)

    Seekell, Raymond; Dever, Rachel; Zhu, Yingxi

    2013-03-01

    Inspired by the superb lubricity of natural synovial fluids for moving articular cartilage joints, we investigate a biomimetic artificial lubricant based on a hydrogel-biopolymer mixture with optimized rheological properties at a microscopic level. Specifically, we examine the structure and rheological relationship of stimuli-responsive poly (N-isopropylacrylamide) (PNIPAM) hydrogel added with hyaluronic acid (HA) to simulate the complexes of HA with a globule protein, lubricin, which are credited as the two key lubricious constituents in natural synovial fluids. By combined microscopic structural characterization and rheology measurement, we tune the rheological and frictional behaviors of HA solutions by optimizing the content of added micron-sized PNIPAM hydrogel particles to form stable PNIPAM-HA network. In a recent work on using zwitterionic hydrogel particles instead of negatively charged PNIPAM, comparable structure and rheological properties of hydrogel-HA aggregates are observed, which may give insight to design new biocompatible lubricants and lubricious coatings for medical ramification.

  14. A strategy for antimicrobial regulation based on fluorescent conjugated oligomer-DNA hybrid hydrogels.

    PubMed

    Cao, Ali; Tang, Yanli; Liu, Yue; Yuan, Huanxiang; Liu, Libing

    2013-06-21

    New fluorescent oligo(phenylene ethynylene)-DNA hydrogels have been prepared and used for the controllable biocidal activity driven by DNase. This study opens a new way of controllable drug release and antimicrobial regulation.

  15. Designing injectable beta-hairpin peptide hydrogels for cartilage tissue engineering application

    NASA Astrophysics Data System (ADS)

    Sinthuvanich, Chomdao

    In this work, it was demonstrated that peptide-based gels having different electrostatic network character but similar mechanical properties can be designed by modulating the primary sequence of the peptides used for self-assembly. As a result, HLT2 and HET1 peptides, having formal charge states of +5 per monomer, were designed using MAX8, a peptide with a charge state of +7 per monomer, as a template. Using gels prepared from all three peptides (MAX8, HLT2, and HET1), it was shown that the electropositive character of the network influences chondrocyte behavior. Specifically, the less electropositive gel (HLT2) is able to maintain chondrocyte viability and phenotype. In contrast, chondrocytes encapsulated in the more positively charged gel (MAX8) are more prone to dedifferentiation, resulting in tissue constructs with inferior mechanical properties. Gels prepared from peptides having the same net charge but differing only in their primary sequences (HLT2 and HET1) were also shown to influence cell behavior, but only during the early period of culturing. If constructs derived from these two different peptide gels are allowed to culture for extended times, their mechanical properties become similar. This suggests that the amino acid composition and sequence of the peptides used to make the gels also influences cell behavior, but perhaps not to the extent that network electrostatics plays. Supplementation of bioactive factors in the culturing media, as opposed to being encapsulated directly in the network, was shown to adversely affect the cellular response resulting in tissue constructs where extracellular matrix (ECM) components are non-uniformly distributed. When bioactive factors were encapsulated and co-delivered with cells, positive results were observed, particularly when cells were co-encapsulated with the growth factor, TGF-β1. The effect of TGF-β1 on cellular response and the mechanical properties of the tissue-engineered constructs is largely governed by

  16. Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels

    NASA Astrophysics Data System (ADS)

    Gogurla, Narendar; Sinha, Arun K.; Naskar, Deboki; Kundu, Subhas C.; Ray, Samit K.

    2016-03-01

    Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms.

  17. Metal nanoparticles triggered persistent negative photoconductivity in silk protein hydrogels.

    PubMed

    Gogurla, Narendar; Sinha, Arun K; Naskar, Deboki; Kundu, Subhas C; Ray, Samit K

    2016-04-14

    Silk protein is a natural biopolymer with intriguing properties, which are attractive for next generation bio-integrated electronic and photonic devices. Here, we demonstrate the negative photoconductive response of Bombyx mori silk protein fibroin hydrogels, triggered by Au nanoparticles. The room temperature electrical conductivity of Au-silk hydrogels is found to be enhanced with the incorporation of Au nanoparticles over the control sample, due to the increased charge transporting networks within the hydrogel. Au-silk lateral photoconductor devices show a unique negative photoconductive response under an illumination of 325 nm, with excitation energy higher than the characteristic metal plasmon resonance band. The enhanced photoconductance yield in the hydrogels over the silk protein is attributed to the photo-oxidation of amino groups in the β-pleated sheets of the silk around the Au nanoparticles followed by the breaking of charge transport networks. The Au-silk nanocomposite does not show any photoresponse under visible illumination because of the localization of excited charges in Au nanoparticles. The negative photoconductive response of hybrid Au-silk under UV illumination may pave the way towards the utilization of silk for future bio-photonic devices using metal nanoparticle platforms. PMID:26996157

  18. Insitu grafting silica nanoparticles reinforced nanocomposite hydrogels

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Han, Chun-Rui; Duan, Jiu-Fang; Xu, Feng; Sun, Run-Cang

    2013-10-01

    Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties.Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties. Electronic supplementary information (ESI) available: FTIR spectra of SNP after silane treatment, dynamic oscillatory shear measurements as a function of frequency, constrained polymer chain analysis by a change in the peak height in loss factor spectra, molecular weight of grafted chains at different stages of gelation, prediction of the SNP reinforcing mechanism in the

  19. Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

    NASA Astrophysics Data System (ADS)

    Reddy, N. Narayana; Ravindra, S.; Reddy, N. Madhava; Rajinikanth, V.; Raju, K. Mohana; Vallabhapurapu, Vijaya Srinivasu

    2015-11-01

    The present work deals with the development of temperature and magnetic responsive hydrogel networks based on poly (N-isopropylacrylamide)/acrylamido propane sulfonic acid. The hydrogel matrices are synthesized by polymerizing N-isopropylacrylamide (NIPAM) monomer in the presence of acrylamido propane sulphonicacid (AMPS) using a cross-linker (N,N-methylenebisacrylamide, MBA) and redox initiating system [ammonium persulphate (APS)/tetramethylethylenediamine (TMEDA)]. The magnetic nanoparticles are generated throughout the hydrogel networks using in situ method by incorporating iron ions and subsequent treatment with ammonia. A series of hydrogel-magnetic nanocomposites (HGMNC) are developed by varying AMPS composition. The synthesized hydrogel magnetic nanocomposites (HGMNC) are characterized by using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Thermal Analyses and Electron Microscopy analysis (Scanning and Transmission Electron Microscope). The metal extraction capacities of the prepared hydrogel (HG) and hydrogel magnetic nanocomposites (HGMNC) were studied at different temperatures. The results suggest that HGMNCs have higher extraction capacity compared to HG and HG loaded iron ions. This data also reveals that the extraction of metals by hydrogel magnetic nanocomposites (HGMNCs) is higher at higher temperatures than room temperature. The prepared HGMNCs are also subjected to hyperthermia (cancer therapy) studies.

  20. SYNTHESIS AND CHARACTERIZATION OF POLYSIALIC ACID/CARBOXYMETHYL CHITOSAN HYDROGEL WITH POTENTIAL FOR DRUG DELIVERY.

    PubMed

    Wu, J R; Zhan, X B; Zheng, Z Y; Zhang, H T

    2015-01-01

    A novel hydrogel was prepared from polysialic acid (PSA) and carboxymethyl chitosan (CMCS) using glutaraldehyde as the cross-linking agent. The resulting PSA-CMCS hydrogel exhibited pH sensitivity, in which the swelling ratio under acidic conditions was higher than those under neutral or alkaline conditions. The swelling ratio of PSA-CMCS hydrogel at equilibrium depended on the medium pH, the cross-linking agent concentration, and the ratio of PSA to CMCS (w/w). Bovine serum albumin (BSA) and 5-fluorouracil (5-FU) were used as model drugs to prepare hydrogel delivery systems. The loading efficiencies of the hydrogel for BSA and 5-FU were 26.25 and 36.74%, respectively. Release behaviors of BSA and 5-FU were influenced by the pH. MTT assays confirmed that PSA-CMCS hydrogel has no cytotoxicity toward the NIH-3T3 cell line; in fact, the 100% aqueous extract of the PSA-CMCS hydrogel enhanced cell growth. These results suggest that PSA-CMCS hydrogel may be a promising pH-sensitive delivery system, especially for hydrophobic chemicals. PMID:26762102

  1. Improved synthesis of hyaluronic acid hydrogel and its effect on tissue augmentation.

    PubMed

    Yan, Xiang Mei; Seo, Moo Seok; Hwang, Eui Jin; Cho, Il Hwan; Hahn, Sei Kwang; Sohn, Uy Dong

    2012-08-01

    HA-HMDA hydrogels were developed by direct amide bond formation between the carboxyl groups of hyaluronic acid (HA) and hexamethylenediamine (HMDA) with an optimized carboxyl group modification in the preliminary experiment. However, these HA-HMDA hydrogels transformed into an unstable liquid form after steam sterilization, and were problematic for application to actual dermal filler. A new method to overcome the problem of the previously developed HA-HMDA hydrogels is to prepare them by adjusting the pH in this study. Not only are these improved HA-HMDA hydrogels prepared with lower amounts of cross-linking and activation agents compared to the previously developed hydrogels, but they also maintain a stable form after steam sterilization. These improved HA-HMDA hydrogels showed higher viscoelasticity and longer lasting effects than the previous ones, despite the fact that the amount of the HMDA used as a cross-linking agent as well as 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) and 1-hydroxybenzotriazole monohydrated (HOBt) used as activation agents were substantially reduced. According to an in vivo test using a wrinkled mouse model, the improved HA-HMDA hydrogels exhibited significantly improved tissue augmentation effects compared to a positive control of Restylane, which is widely used for the tissue augmentation throughout the world. Furthermore, histological analysis revealed excellent biocompatibility and safety of the improved synthesized HA-HMDA hydrogels.

  2. Mechanical and viscoelastic properties of cellulose nanocrystals reinforced poly(ethylene glycol) nanocomposite hydrogels.

    PubMed

    Yang, Jun; Han, Chun-Rui; Duan, Jiu-Fang; Xu, Feng; Sun, Run-Cang

    2013-04-24

    The preparation and mechanical properties of elastomeric nanocomposite hydrogels consisting of cellulose nanocrystals (CNCs) and poly(ethylene glycol) (PEG) are reported. The aqueous nanocomposite CNC/PEG precursor solutions covalently cross-linked through a one-stage photocross-linking process. The mechanical properties of nanocomposite hydrogels, including Young's modulus (E), fracture stress (σ), and fracture strain (ε), were measured as a function of CNC volume fraction (φCNC, 0.2-1.8%, v/v) within polymeric matrix. It was found that the homogeneously dispersed nanocomposite hydrogels can be prepared with φCNC being less than 1.5%, whereas the heterogeneous nanocomposite hydrogels were obtained with φCNC being higher than 1.5%. The nanocomposite hydrogels exhibited higher strengths and flexibilities when compared with neat PEG hydrogels, where the modulus, fracture stress, and fracture strain enhanced by a factor of 3.48, 5, and 3.28, respectively, over the matrix material alone at 1.2% v/v CNC loading. Oscillatory shear data indicated the CNC-PEG nanocomposite hydrogels were more viscous than the neat PEG hydrogels and were efficient at energy dissipation due to the reversible interactions between CNC and PEG polymer chains. It was proposed that the strong gel viscoelastic behavior and the mechanical reinforcement were related to "filler network", where the temporary interactions between CNC and PEG interfered with the covalent cross-links of PEG. PMID:23534336

  3. Towards temperature driven forward osmosis desalination using Semi-IPN hydrogels as reversible draw agents.

    PubMed

    Cai, Yufeng; Shen, Wenming; Loo, Siew Leng; Krantz, William B; Wang, Rong; Fane, Anthony G; Hu, Xiao

    2013-07-01

    We report a study to explore new materials and a new concept for temperature driven quasi-continuous desalination using hydrogels as draw agents in forward osmosis (FO). This concept is enabled by the design and preparation of thermally responsive hydrogels having a semi-interpenetrating network (semi-IPN) structure. Thermally responsive semi-IPN hydrogels were synthesized by polymerization of N-isopropylacrylamide (NIPAm) in the presence of polysodium acrylate (PSA) or polyvinyl alcohol (PVA). Their functions as draw agents in FO were systematically studied and compared with hydrogels prepared from the PNIPAm homopolymer or the NIPAM-SA copolymer. While the semi-IPN hydrogels displayed the desirable balanced thermally responsive swelling and dewatering behavior, the NIPAm-SA copolymer hydrogels were found to have poor dewatering behavior, making them unsuitable for a continuous temperature driven desalination process. At 40 °C, the semi-IPN hydrogels rapidly release nearly 100% of the water absorbed during the FO drawing process carried out at room temperature. Results clearly indicate the potential of semi-IPN hydrogels as semi-solid draw agents in the FO process, in which quasi-continuous desalination could be achieved by cyclic heating and cooling within a moderate temperature change. PMID:23726714

  4. Towards temperature driven forward osmosis desalination using Semi-IPN hydrogels as reversible draw agents.

    PubMed

    Cai, Yufeng; Shen, Wenming; Loo, Siew Leng; Krantz, William B; Wang, Rong; Fane, Anthony G; Hu, Xiao

    2013-07-01

    We report a study to explore new materials and a new concept for temperature driven quasi-continuous desalination using hydrogels as draw agents in forward osmosis (FO). This concept is enabled by the design and preparation of thermally responsive hydrogels having a semi-interpenetrating network (semi-IPN) structure. Thermally responsive semi-IPN hydrogels were synthesized by polymerization of N-isopropylacrylamide (NIPAm) in the presence of polysodium acrylate (PSA) or polyvinyl alcohol (PVA). Their functions as draw agents in FO were systematically studied and compared with hydrogels prepared from the PNIPAm homopolymer or the NIPAM-SA copolymer. While the semi-IPN hydrogels displayed the desirable balanced thermally responsive swelling and dewatering behavior, the NIPAm-SA copolymer hydrogels were found to have poor dewatering behavior, making them unsuitable for a continuous temperature driven desalination process. At 40 °C, the semi-IPN hydrogels rapidly release nearly 100% of the water absorbed during the FO drawing process carried out at room temperature. Results clearly indicate the potential of semi-IPN hydrogels as semi-solid draw agents in the FO process, in which quasi-continuous desalination could be achieved by cyclic heating and cooling within a moderate temperature change.

  5. Physicochemical foundations and structural design of hydrogels in medicine and biology.

    PubMed

    Peppas, N A; Huang, Y; Torres-Lugo, M; Ward, J H; Zhang, J

    2000-01-01

    Hydrogels are cross-linked hydrophilic polymers that can imbibe water or biological fluids. Their biomedical and pharmaceutical applications include a very wide range of systems and processes that utilize several molecular design characteristics. This review discusses the molecular structure, dynamic behavior, and structural modifications of hydrogels as well as the various applications of these biohydrogels. Recent advances in the preparation of three-dimensional structures with exact chain conformations, as well as tethering of functional groups, allow for the preparation of promising new hydrogels. Meanwhile, intelligent biohydrogels with pH- or temperature-sensitivity continue to be important materials in medical applications.

  6. Development of an arginine-based cationic hydrogel platform: Synthesis, characterization and biomedical applications.

    PubMed

    Pang, Xuan; Wu, Jun; Chu, Chih-Chang; Chen, Xuesi

    2014-07-01

    A series of biodegradable and biocompatible cationic hybrid hydrogels was developed from water-soluble arginine-based unsaturated polymer (Arg-AG) and poly(ethylene glycol) diacrylate (PEG-DA) by a photocrosslinking method. The physicochemical, mechanical and biological properties of these hydrogels were intensively examined. The hydrogels were characterized in terms of equilibrium swelling ratio (Qeq), compression modulus and interior morphology. The effects of the chemical structure of the two Arg-AG precursors and the feed ratio of these precursors on the properties of resulting hybrid hydrogels were investigated. The crosslinking density and mechanical strength of the hybrid hydrogels increased with an increase in allylglycine (AG) content in the Arg-AG precursor, as the gelation efficiency (Gf) increased from 80% to 90%, but the swelling and pore size of the hybrid hydrogels decreased as the equilibrium swelling weight (Qeq) decreased from 1890% to 1330% and the pore size from 28 to 22 μm. The short-term in vitro biodegradation properties of hydrogels were investigated as a function of Arg-AG chemical structures and enzymes. Hybrid hydrogels showed faster biodegradation in an enzyme solution than in a phosphate-buffered saline solution. Bovine serum albumin and insulin release profiles indicated that this cationic hydrogel system could significantly improve the sustained release of the negatively charged proteins. The cellular response of the hybrid hydrogels was preliminarily evaluated by cell attachment, encapsulation and proliferation tests using live-dead and MTT assay. The results showed that the hybrid hydrogels supported cell attachment well and were nontoxic to the cells.

  7. Degradation of polysaccharide hydrogels seeded with bone marrow stromal cells.

    PubMed

    Jahromi, Shiva H; Grover, Liam M; Paxton, Jennifer Z; Smith, Alan M

    2011-10-01

    In order to produce hydrogel cell culture substrates that are fit for the purpose, it is important that the mechanical properties are well understood not only at the point of cell seeding but throughout the culture period. In this study the change in the mechanical properties of three biopolymer hydrogels alginate, low methoxy pectin and gellan gum have been assessed in cell culture conditions. Samples of the gels were prepared encapsulating rat bone marrow stromal cells which were then cultured in osteogenic media. Acellular samples were also prepared and incubated in standard cell culture media. The rheological properties of the gels were measured over a culture period of 28 days and it was found that the gels degraded at very different rates. The degradation occurred most rapidly in the order alginate > Low methoxy pectin > gellan gum. The ability of each hydrogel to support differentiation of bone marrow stromal cells to osteoblasts was also verified by evidence of mineral deposits in all three of the materials. These results highlight that the mechanical properties of biopolymer hydrogels can vary greatly during in vitro culture, and provide the potential of selecting hydrogel cell culture substrates with mechanical properties that are tissue specific.

  8. Chirality-Mediated Mechanical and Structural Properties of Oligopeptide Hydrogels

    SciTech Connect

    Taraban, Marc B.; Feng, Yue; Hammouda, Boualem; Hyland, Laura L.; Yu, Y. Bruce

    2012-10-29

    The origin and the effects of homochirality in the biological world continuously stimulate numerous hypotheses and much debate. This work attempts to look at the biohomochirality issue from a different angle - the mechanical properties of the bulk biomaterial and their relation to nanoscale structures. Using a pair of oppositely charged peptides that co-assemble into hydrogels, we systematically investigated the effect of chirality on the mechanical properties of these hydrogels through different combinations of syndiotactic and isotactic peptides. It was found that homochirality confers mechanical advantage, resulting in a higher elastic modulus and strain yield value. Yet, heterochirality confers kinetic advantage, resulting in faster gelation. Structurally, both homochiral and heterochiral hydrogels are made of fibers interconnected by lappet-like webs, but the homochiral peptide fibers are thicker and denser. These results highlight the possible role of biohomochirality in the evolution and/or natural selection of biomaterials.

  9. Hybrid collagen-based hydrogels with embedded montmorillonite nanoparticles.

    PubMed

    Nistor, Manuela Tatiana; Vasile, Cornelia; Chiriac, Aurica P

    2015-08-01

    Montmorillonite nanoparticles have been physically incorporated within a crosslinked collagen/poly(N-isopropyl acrylamide) network in order to adjust the properties of the stimuli-responsive hybrid systems. The research underlines both the influence of hydrogel composition and nanoparticle type on hybrid hydrogel properties. The dispersion of the montmorillonite nanoparticles in polymeric matrix have been visualized by SEM, TEM and AFM techniques and quantitatively and qualitatively estimated using near infrared chemical imaging. The electrical charge of the nanoparticles influenced the polymeric chain arrangement and the pore size. The morphologies of the nanoparticulated layers are partially exfoliated or intercalated and uniformly dispersed through the polymeric semi-interpenetrated network based on collagen and poly(N-isopropyl acrylamide). The hybrid hydrogels exhibit pseudoplastic behavior and the addition of nanoparticles has resulted in the increase of the complex viscosity. The adhesion capacity was affected mainly by the presence of organically modified montmorillonites. PMID:26042709

  10. Solvothermal preparation of an electrocatalytic metalloporphyrin MOF thin film and its redox hopping charge-transfer mechanism.

    PubMed

    Ahrenholtz, Spencer R; Epley, Charity C; Morris, Amanda J

    2014-02-12

    A thin film of a metalloporphyrin metal-organic framework consisting of [5,10,15,20-(4-carboxyphenyl)porphyrin]Co(III) (CoTCPP) struts bound by linear trinuclear Co(II)-carboxylate clusters has been prepared solvothermally on conductive fluorine-doped tin oxide substrates. Characterization of this mesoporous thin film material, designated as CoPIZA/FTO, which is equipped with large cavities and access to metal active sites, reveals an electrochemically active material. Cyclic voltammetry displays a reversible peak with E(1/2) at -1.04 V vs ferrocyanide attributed to the (Co(III/II)TCPP)CoPIZA redox couple and a quasi-reversible peak at -1.45 V vs ferrocyanide, which corresponds to the reduction of (Co(II/I)TCPP)CoPIZA. Analysis of the spectroelectrochemical response for the (Co(II/I)TCPP)CoPIZA redox couple revealed non-Nernstian reduction with a nonideality factor of 2 and an E(1/2) of -1.39 V vs ferrocyanide. The film was shown to retain its structural integrity with applied potential, as was demonstrated spectroelectrochemically with maintenance of isosbestic points at 430, 458, and 544 nm corresponding to the (Co(III/II)TCPP)CoPIZA transition and at 390 and 449 nm corresponding to the (Co(II/I)TCPP)CoPIZA transition. The mechanism of charge transport through the film is proposed to be a redox hopping mechanism, which is supported by both cyclic voltammetry and spectroelectrochemistry. A fit of the time-dependent spectroelectrochemical data to a modified Cottrell equation gave an apparent diffusion coefficient of 7.55 (±0.05) × 10(-14) cm(2)/s for ambipolar electron and cation transport throughout the film. Upon reduction of the metalloporphyrin struts to (Co(I)TCPP)CoPIZA, the CoPIZA thin film demonstrated catalytic activity for the reduction of carbon tetrachloride. PMID:24437480

  11. Tunable bioadhesive copolymer hydrogels of thermoresponsive poly(N-isopropyl acrylamide) containing zwitterionic polysulfobetaine.

    PubMed

    Chang, Yung; Yandi, Wetra; Chen, Wen-Yih; Shih, Yu-Ju; Yang, Chang-Chung; Chang, Yu; Ling, Qing-Dong; Higuchi, Akon

    2010-04-12

    This work describes a novel tunable bioadhesive hydrogel of thermoresponsive N-isopropylacrylamide (NIPAAm) containing zwitterionic sulfobetaine methacrylate (SBMA). This novel hydrogel highly regulates general bioadhesive foulants through the adsorption of plasma proteins, the adhesion of human platelets and cells, and the attachment of bacteria. In this investigation, nonionic hydrogels of polyNIPAAm, zwitterionic hydrogels of polySBMA, and three copolymeric hydrogels of NIPAAm and SBMA (poly(NIPAAm-co-SBMA)) were prepared. The copolymeric hydrogels exhibited controllable temperature-dependent swelling behaviors and showed stimuli-responsive phase characteristics in the presence of salts. The interactions of these hydrogels with biomolecules and microorganisms were demonstrated by protein adsorption, cell adhesion, and bacterial attachment, which allowed us to evaluate their bioadhesive properties. An enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies was used to measure different plasma protein adsorptions on the prepared hydrogel surfaces. At a physiological temperature, the high content of the nonionic polyNIPAAm in poly(NIPAAm-co-SBMA) hydrogel exhibits a high protein adsorption due to the interfacial exposure of polyNIPAAm-rich hydrophobic domains. A relatively high content of polySBMA in poly(NIPAAm-co-SBMA) hydrogel exhibits reduced amounts of protein adsorption due to the interfacial hydration of polySBMA-rich hydrophilic segments. The attachment of platelets and the spreading of cells were only observed on polyNIPAAm-rich hydrogel surfaces. Interestingly, the incorporation of zwitterionic SBMA units into the polyNIPAAm gels was found to accelerate the hydration of the cell-cultured surfaces and resulted in more rapid cell detachment. Such copolymer gel surface was shown to be potentially useful for triggered cell detachment. In addition, the interactions of hydrogels with bacteria were also evaluated. The polySBMA-rich hydrogels

  12. Heparin-based hydrogels with tunable sulfation & degradation for anti-inflammatory small molecule delivery.

    PubMed

    Peng, Yifeng; Tellier, Liane E; Temenoff, Johnna S

    2016-08-16

    Sustained release of anti-inflammatory agents remains challenging for small molecule drugs due to their low molecular weight and hydrophobicity. Therefore, the goal of this study was to control the release of a small molecule anti-inflammatory agent, crystal violet (CV), from hydrogels fabricated with heparin, a highly sulfated glycosaminoglycan capable of binding positively-charged molecules such as CV. In this system, both electrostatic interactions between heparin and CV and hydrogel degradation were tuned simultaneously by varying the level of heparin sulfation and varying the amount of dithiothreitol within hydrogels, respectively. It was found that heparin sulfation significantly affected CV release, whereby more sulfated heparin hydrogels (Hep and Hep(-N)) released CV with near zero-order release kinetics (R-squared values between 0.96-0.99). Furthermore, CV was released more quickly from fast-degrading hydrogels than slow-degrading hydrogels, providing a method to tune total CV release between 5-15 days while maintaining linear release kinetics. In particular, N-desulfated heparin hydrogels exhibited efficient CV loading (∼90% of originally included CV), near zero-order CV release kinetics, and maintenance of CV bioactivity after release, making this hydrogel formulation a promising CV delivery vehicle for a wide range of inflammatory diseases. PMID:27447003

  13. Effects of Chitin Whiskers on Physical Properties and Osteoblast Culture of Alginate Based Nanocomposite Hydrogels.

    PubMed

    Huang, Yao; Yao, Mengyu; Zheng, Xing; Liang, Xichao; Su, Xiaojuan; Zhang, Yu; Lu, Ang; Zhang, Lina

    2015-11-01

    Novel nanocomposite hydrogels composed of polyelectrolytes alginate and chitin whiskers with biocompatibility were successfully fabricated based on the pH-induced charge shifting behavior of chitin whiskers. The chitin whiskers with mean length and width of 300 and 20 nm were uniformly dispersed in negatively charged sodium alginate aqueous solution, leading to the formation of the homogeneous nanocomposite hydrogels. The experimental results indicated that their mechanical properties were significantly improved compared to alginate hydrogel and the swelling trends were inhibited as a result of the strong electrostatic interactions between the chitin whiskers and alginate. The nanocomposite hydrogels exhibited certain crystallinity and hierarchical structure with nanoscale chitin whiskers, similar to the structure of the native extracellular matrix. Moreover, the nanocomposite hydrogels were successfully applied as bone scaffolds for MC3T3-E1 osteoblast cells, showing their excellent biocompatibility and low cytotoxicity. The results of fluorescent micrographs and scanning electronic microscope (SEM) images revealed that the addition of chitin whiskers into the nanocomposite hydrogels markedly promoted the cell adhesion and proliferation of the osteoblast cells. The biocompatible nanocomposite hydrogels have potential application in bone tissue engineering. PMID:26393272

  14. Thermally Responsive Hydrogel Blends: A General Drug Carrier Model for Controlled Drug Release.

    PubMed

    Ma, Chongbo; Shi, Ye; Pena, Danilo A; Peng, Lele; Yu, Guihua

    2015-06-15

    Thermally responsive hydrogels have drawn significant research attention recently because of their simple use as drug carrier at human body temperature. Here we design a hybrid hydrogel that incorporates a hydrophilic polymer, polyethyleneimine (PEI), into the thermally responsive hydrogel poly(N-isopropylacrylamide) (PNIPAm), as a general drug carrier model for controlled drug release. In this work, on one hand, PEI modifies the structure and the size of the pores in the PNIPAm hydrogel. On the other hand, PEI plays an important role in tuning the water content in the hydrogel and controls the water release rate of the hydrogel below the lower critical solution temperature (LCST), resulting in a tunable release rate of the drugs at human body temperature (37 °C). Different release rates are shown as different amounts of PEI are incorporated. PEI controls the release rate, dependent on the charge characteristics of the drugs. The hydrogel blends described in this work extend the concept of a general drug carrier for loading both positively and negatively charged drugs, as well as the controlled release effect.

  15. Effects of Chitin Whiskers on Physical Properties and Osteoblast Culture of Alginate Based Nanocomposite Hydrogels.

    PubMed

    Huang, Yao; Yao, Mengyu; Zheng, Xing; Liang, Xichao; Su, Xiaojuan; Zhang, Yu; Lu, Ang; Zhang, Lina

    2015-11-01

    Novel nanocomposite hydrogels composed of polyelectrolytes alginate and chitin whiskers with biocompatibility were successfully fabricated based on the pH-induced charge shifting behavior of chitin whiskers. The chitin whiskers with mean length and width of 300 and 20 nm were uniformly dispersed in negatively charged sodium alginate aqueous solution, leading to the formation of the homogeneous nanocomposite hydrogels. The experimental results indicated that their mechanical properties were significantly improved compared to alginate hydrogel and the swelling trends were inhibited as a result of the strong electrostatic interactions between the chitin whiskers and alginate. The nanocomposite hydrogels exhibited certain crystallinity and hierarchical structure with nanoscale chitin whiskers, similar to the structure of the native extracellular matrix. Moreover, the nanocomposite hydrogels were successfully applied as bone scaffolds for MC3T3-E1 osteoblast cells, showing their excellent biocompatibility and low cytotoxicity. The results of fluorescent micrographs and scanning electronic microscope (SEM) images revealed that the addition of chitin whiskers into the nanocomposite hydrogels markedly promoted the cell adhesion and proliferation of the osteoblast cells. The biocompatible nanocomposite hydrogels have potential application in bone tissue engineering.

  16. Hydrogel Containing Nanoparticle-Stabilized Liposomes for Topical Antimicrobial Delivery

    PubMed Central

    2015-01-01

    Adsorbing small charged nanoparticles onto the outer surfaces of liposomes has become an effective strategy to stabilize liposomes against fusion prior to “seeing” target bacteria, yet allow them to fuse with the bacteria upon arrival at the infection sites. As a result, nanoparticle-stabilized liposomes have become an emerging drug delivery platform for treatment of various bacterial infections. To facilitate the translation of this platform for clinical tests and uses, herein we integrate nanoparticle-stabilized liposomes with hydrogel technology for more effective and sustained topical drug delivery. The hydrogel formulation not only preserves the structural integrity of the nanoparticle-stabilized liposomes, but also allows for controllable viscoeleasticity and tunable liposome release rate. Using Staphylococcus aureus bacteria as a model pathogen, we demonstrate that the hydrogel formulation can effectively release nanoparticle-stabilized liposomes to the bacterial culture, which subsequently fuse with bacterial membrane in a pH-dependent manner. When topically applied onto mouse skin, the hydrogel formulation does not generate any observable skin toxicity within a 7-day treatment. Collectively, the hydrogel containing nanoparticle-stabilized liposomes hold great promise for topical applications against various microbial infections. PMID:24483239

  17. Strong and Robust Polyaniline-Based Supramolecular Hydrogels for Flexible Supercapacitors.

    PubMed

    Li, Wanwan; Gao, Fengxian; Wang, Xiaoqian; Zhang, Ning; Ma, Mingming

    2016-08-01

    We report a supramolecular strategy to prepare conductive hydrogels with outstanding mechanical and electrochemical properties, which are utilized for flexible solid-state supercapacitors (SCs) with high performance. The supramolecular assembly of polyaniline and polyvinyl alcohol through dynamic boronate bond yields the polyaniline-polyvinyl alcohol hydrogel (PPH), which shows remarkable tensile strength (5.3 MPa) and electrochemical capacitance (928 F g(-1) ). The flexible solid-state supercapacitor based on PPH provides a large capacitance (306 mF cm(-2) and 153 F g(-1) ) and a high energy density of 13.6 Wh kg(-1) , superior to other flexible supercapacitors. The robustness of the PPH-based supercapacitor is demonstrated by the 100 % capacitance retention after 1000 mechanical folding cycles, and the 90 % capacitance retention after 1000 galvanostatic charge-discharge cycles. The high activity and robustness enable the PPH-based supercapacitor as a promising power device for flexible electronics. PMID:27328742

  18. Optimization of charge carrier transport balance for performance improvement of PDPP3T-based polymer solar cells prepared using a hot solution.

    PubMed

    Wang, Jian; Zhang, Fujun; Zhang, Miao; Wang, Wenbin; An, Qiaoshi; Li, Lingliang; Sun, Qianqian; Tang, Weihua; Zhang, Jian

    2015-04-21

    Polymer solar cells (PSCs), with poly(diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the active layers, were fabricated using solutions of different temperatures. The best power conversion efficiency (PCE) of the PSCs prepared using a hot solution was about 6.22%, which is better than 5.54% for PSCs prepared using cool (room temperature) solutions and 5.85% for PSCs prepared using cool solutions with a 1,8-diiodooctane (DIO) solvent additive. The underlying reasons for the improved PCE of the PSCs prepared using a hot solution could be attributed to the more dispersive donor and acceptor distribution in the active layer, resulting in a better bi-continuous interpenetrating network for exciton dissociation and charge carrier transport. An enhanced and more balanced charge carrier transport in the active layer is obtained for the PSCs prepared using a hot solution, which can be determined from the J-V curves of the related hole-only and electron-only devices.

  19. Template polymerization synthesis of hydrogel and silica composite for sorption of some rare earth elements.

    PubMed

    Borai, E H; Hamed, M G; El-kamash, A M; Siyam, T; El-Sayed, G O

    2015-10-15

    New sorbents containing 2-acrylamido 2-methyl propane sulphonic acid monomer onto poly(vinyl pyrilidone) P(VP-AMPS) hydrogel and P(VP-AMPS-SiO2) composite have been synthesized by radiation template polymerization. The effect of absorbed dose rate (kGy), crosslinker concentration and polymer/monomer ratio on the degree of template polymerization of P(VP-AMPS) hydrogel was studied. The degree of polymerization was evaluated by the calculated percent conversion and swelling degree. The maximum capacity of P(VP-AMPS) hydrogel toward Cu(+2) metal ion found to be 91 mg/gm. The polymeric composite P(VP-AMPS-SiO2) has been successfully synthesized. The structure of the prepared hydrogel and composite were confirmed by FTIR, thermal analysis (TGA and DTA) and SEM micrograph. Batch adsorption studies for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(+2) metal ions on the prepared hydrogel and composite were investigated as a function of shaking time, pH and metal ion concentration. The sorption efficiency of the prepared hydrogel and composite toward light rare earth elements (LREEs) are arranged in the order La(3+)>Ce(3+)>Nd(3+)>Eu(3+). The obtained results demonstrated the superior adsorption capacity of the composite over the polymeric hydrogel. The maximum capacity of the polymeric composite was found to be 116, 103, 92, 76, 74 mg/gm for La(3+), Ce(3+), Nd(3+), Eu(3+) and Pb(2+) metal ions respectively.

  20. Biosynthetic hydrogels--studies on chemical and physical characteristics on long-term cellular response for tissue engineering.

    PubMed

    Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

    2014-07-01

    Biosynthetic hydrogels can meet the drawbacks caused by natural and synthetic ones for biomedical applications. In the current article we present a novel biosynthetic alginate-poly(propylene fumarate) copolymer based chemically crosslinked hydrogel scaffolds for cardiac tissue engineering applications. Partially crosslinked PA hydrogel and fully cross linked PA-A hydrogel scaffolds were prepared. The influence of chemical and physical (morphology and architecture of hydrogel) characteristics on the long term cellular response was studied. Both these hydrogels were cytocompatible and showed no genotoxicity upon contact with fibroblast cells. Both PA and PA-A were able to resist deleterious effects of reactive oxygen species and sustain the viability of L929 cells. The hydrogel incubated oxidative stress induced cells were capable of maintaining the intra cellular reduced glutathione (GSH) expression to the normal level confirmed their protective effect. Relatively the PA hydrogel was found to be unstable in the cell culture medium. The PA-A hydrogel was able to withstand appreciable cyclic stretching. The cyclic stretching introduced complex macro and microarchitectural features with interconnected pores and more structured bound water which would provide long-term viability of around 250% after the 24th day of culture. All these qualities make PA-A hydrogel form a potent candidate for cardiac tissue engineering.

  1. Hydrogels synthesised through photoinitiator-free photopolymerisation technique for delivering drugs including a tumour-tracing porphyrin

    NASA Astrophysics Data System (ADS)

    Ng, Loo-Teck; Swami, Salesh; Gordon-Thomson, Clare

    2006-05-01

    Hydrogels were synthesised using the photoinitiator-free photopolymerisation technique involving interactions between donor/acceptor pairs for delivering drugs of different molecular weights including a porphyrin used as a tumour-tracing agent. N-(5-hydroxy) pentylmaleimide, an acceptor, formed hydrogels with N-vinyl-2-pyrrolidinone, 2-hydroxyethyl methacrylate and N-vinylcaprolactum. Glucosamine, an effective H-donor in enhancing polymerisation as shown by Differential Photocalorimetric results, was found unsuitable for hydrogel preparation. Drugs of different molecular weights releasing at the same rate was discussed. The hydrogels were found to have no toxic effects and were biocompatible with a human keratinocyte cell line.

  2. Synthesis and characterization of thermally and chemically gelling injectable hydrogels for tissue engineering.

    PubMed

    Ekenseair, Adam K; Boere, Kristel W M; Tzouanas, Stephanie N; Vo, Tiffany N; Kasper, F Kurtis; Mikos, Antonios G

    2012-06-11

    Novel, injectable hydrogels were developed that solidify through a physical and chemical dual-gelation mechanism upon preparation and elevation of temperature to 37 °C. A thermogelling, poly(N-isopropylacrylamide)-based macromer with pendant epoxy rings and a hydrolytically degradable polyamidoamine-based diamine cross-linker were synthesized, characterized, and combined to produce in situ forming hydrogel constructs. Network formation through the epoxy-amine reaction was shown to be rapid and facile, and the progressive incorporation of the hydrophilic polyamidoamine cross-linker into the hydrogel was shown to mitigate the often problematic tendency of thermogelling materials to undergo significant postformation gel syneresis. The results suggest that this novel class of injectable hydrogels may be attractive substrates for tissue engineering applications due to the synthetic versatility of the component materials and beneficial hydrogel gelation kinetics and stability.

  3. Synthesis and Characterization of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering

    PubMed Central

    Ekenseair, Adam K.; Boere, Kristel W. M.; Tzouanas, Stephanie N.; Vo, Tiffany N.; Kasper, F. Kurtis; Mikos, Antonios G.

    2012-01-01

    Novel, injectable hydrogels were developed that solidify through a dual-gelation, physical and chemical, mechanism upon preparation and elevation of temperature to 37°C. A thermogelling, poly(N-isopropylacrylamide)-based macromer with pendant epoxy rings and a hydrolytically-degradable polyamidoamine-based diamine crosslinker were synthesized, characterized, and combined to produce in situ forming hydrogel constructs. Network formation through the epoxy-amine reaction was shown to be rapid and facile, and the progressive incorporation of the hydrophilic polyamidoamine crosslinker into the hydrogel was shown to mitigate the often problematic tendency of thermogelling materials to undergo significant post-formation gel syneresis. The results suggest that this novel class of injectable hydrogels may be attractive substrates for tissue engineering applications due to the synthetic versatility of the component materials and beneficial hydrogel gelation kinetics and stability. PMID:22554407

  4. Synthesis and Characterization of Cellulose-Based Hydrogels to Be Used as Gel Electrolytes

    PubMed Central

    Navarra, Maria Assunta; Dal Bosco, Chiara; Serra Moreno, Judith; Vitucci, Francesco Maria; Paolone, Annalisa; Panero, Stefania

    2015-01-01

    Cellulose-based hydrogels, obtained by tuned, low-cost synthetic routes, are proposed as convenient gel electrolyte membranes. Hydrogels have been prepared from different types of cellulose by optimized solubilization and crosslinking steps. The obtained gel membranes have been characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical tests in order to investigate the crosslinking occurrence and modifications of cellulose resulting from the synthetic process, morphology of the hydrogels, their thermal stability, and viscoelastic-extensional properties, respectively. Hydrogels liquid uptake capability and ionic conductivity, derived from absorption of aqueous electrolytic solutions, have been evaluated, to assess the successful applicability of the proposed membranes as gel electrolytes for electrochemical devices. To this purpose, the redox behavior of electroactive species entrapped into the hydrogels has been investigated by cyclic voltammetry tests, revealing very high reversibility and ion diffusivity. PMID:26633528

  5. A modified emulsion gelation technique to improve buoyancy of hydrogel tablets for floating drug delivery systems.

    PubMed

    Yom-Tov, Ortal; Seliktar, Dror; Bianco-Peled, Havazelet

    2015-10-01

    The use of buoyant or floating hydrogel tablets is of particular interest in the sustained release of drugs to the stomach. They have an ability to slow the release rates of drugs by prolonging their absorption window in the upper part of the gastrointestinal (GI) tract. In this study we synthesized bioactive hydrogels that have sustainable release rates for drugs in the stomach based on a hydrogel preparation technique that employs emulsifying surfactants. The emulsion gelation technique, which encapsulates oil droplets within the hydrogels during crosslinking, was used to decrease their specific gravity in aqueous environments, resulting in floating drug release depots. Properties such as swelling, buoyancy, density and drug release were manipulated by changing the polymer concentrations, surfactant percentages and the oil:polymer ratios. The relationship between these properties and the hydrogel's floating lag time was documented. The potential for this material to be used as a floating drug delivery system was demonstrated.

  6. Fabrication of triple-layered magnetite-hydrogel-gold nanocomposites for biomedical applications.

    PubMed

    Lim, Sera; Lee, Sang-Wha

    2012-02-01

    Magnetite-hydrogel-gold nanocomposites with optical-active, thermo-responsive, and magnetism have been prepared by the following consecutive steps. Hydrogel-encapsulated magnetites were first synthesized by the combination of sol-gel reaction and radical polymerization process, and the resulting magnetic hydrogels were subsequently bound with nano-sized Au (1-3 nm) via a molecular linkage of diamine ligand which was covalently bonded to the carboxylic groups on the hydrogel surface. Au seeds anchored on the magnetic hydrogels were further reduced into nano-scale Au layer which induced the distinct red-shift of absorption band into NIR region. The optical properties and surface morphology of the nanocomposites were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). PMID:22629930

  7. Biomineralization of calcium phosphate crystals on chitin nanofiber hydrogel for bone regeneration material.

    PubMed

    Kawata, Mari; Azuma, Kazuo; Izawa, Hironori; Morimoto, Minoru; Saimoto, Hiroyuki; Ifuku, Shinsuke

    2016-01-20

    We previously reported a chitin nanofiber hydrogel from squid pen β-chitin by a simple NaOH treatment. In the present study, a calcium phosphate/chitin nanofiber hydrogel was prepared for bone tissue engineering. Calcium phosphate was mineralized on the hydrogel by incubation in a solution of diammonium hydrogen phosphate solution followed by calcium nitrate tetrahydrate. X-ray diffractometry and Fourier transform infrared spectroscopy showed the formation of calcium phosphate crystals. The morphology of the calcium phosphate crystals changed depending on the calcification time. After mineralization, the mechanical properties of the hydrogel improved due to the reinforcement effect of calcium phosphate crystal. In an animal experiment, calcium phosphate/chitin nanofiber hydrogel accelerated mineralization in subcutaneous tissues. Morphological osteoblasts were observed. PMID:26572435

  8. Hydrogels with Rapid Thermal-Responsibility by Using Liquid Crystallite as Template

    NASA Astrophysics Data System (ADS)

    Zhang, Qingsong; Chen, Kun; Zhao, Yiping; Li, Chen

    2011-06-01

    To improve temperature-sensitivity of conventional poly(N-isopropylacrylamide) (PNIPAM) hydrogel, a kind of lyotropic liquid crystal based on polyoxyethylene 20 cetyl ether (Brij 58, C16E20) was used as template to prepare nanostructured hydrogel. The structure, morphology swelling behavior and temperature-sensitivity of confined PNIPAM hydrogel were characterized. SEM images showed that polymerization of N-isopropylacrylamide (NIPAM) in Brij 58 solution formed hydrogel with honeycomb structure. Compared to pure PNIPAM hydrogel, the swelling rate increases. The time for losing water was greatly shortened. The thermal-responsibility measured by differential scanning calorimeters (DSC) was improved remarkably. Finally, as for oscillatory swelling/deswelling behaviors, rapid recovering could be found by alternating temperature from 20 to 37°C.

  9. Biocompatibility Evaluation of a New Hydrogel Dressing Based on Polyvinylpyrrolidone/Polyethylene Glycol

    PubMed Central

    Biazar, Esmaeil; Roveimiab, Ziba; Shahhosseini, Gholamreza; Khataminezhad, Mohammadreza; Zafari, Mandana; Majdi, Ali

    2012-01-01

    The composition of the dressings is based on polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and agar. The electron beam irradiation technique has been used to prepare hydrogel wound dressings. The in vitro biocompatibility of the hydrogel was investigated by check samples (hydrocolloid Comfeel), antibacterial test (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia Coli k12), anti fungal test (Candida Albicans) and cytotoxicity test (Fibroblast L929). Results have shown cell attachment characteristics and nontoxicity of all samples. Antibacterial testing also showed that the antibacterial effect of the hydrogel sample to the check sample increased to 30%. Also, investigation of antifungal analysis did not show any trace of fungi growth on the surface of the hydrogel, whereas antifungal effect did not observe on the surface of the check sample. Finally, this hydrogel sample showed a good in vitro biocompatibility. PMID:21860588

  10. Biocompatibility evaluation of a new hydrogel dressing based on polyvinylpyrrolidone/polyethylene glycol.

    PubMed

    Biazar, Esmaeil; Roveimiab, Ziba; Shahhosseini, Gholamreza; Khataminezhad, Mohammadreza; Zafari, Mandana; Majdi, Ali

    2012-01-01

    The composition of the dressings is based on polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and agar. The electron beam irradiation technique has been used to prepare hydrogel wound dressings. The in vitro biocompatibility of the hydrogel was investigated by check samples (hydrocolloid Comfeel), antibacterial test (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia Coli k12), anti fungal test (Candida Albicans) and cytotoxicity test (Fibroblast L929). Results have shown cell attachment characteristics and nontoxicity of all samples. Antibacterial testing also showed that the antibacterial effect of the hydrogel sample to the check sample increased to 30%. Also, investigation of antifungal analysis did not show any trace of fungi growth on the surface of the hydrogel, whereas antifungal effect did not observe on the surface of the check sample. Finally, this hydrogel sample showed a good in vitro biocompatibility. PMID:21860588

  11. Modified pineapple peel cellulose hydrogels embedded with sepia ink for effective removal of methylene blue.

    PubMed

    Dai, Hongjie; Huang, Huihua

    2016-09-01

    Novel composite hydrogels based on pineapple peel cellulose and sepia ink were synthesized by homogeneous acetylation of cellulose in ionic liquid 1-butyl-3-methylimidazolium chloride. The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, thermogravimetry and differential scanning calorimetry. The effects of acetylation time, acetylation temperature, molar ratio of acetic anhydride/anhydroglucose unit and the additive amount of sepia ink on methylene blue adsorption capacity of the hydrogels embedded with sepia ink were also investigated. Methylene blue adsorption of the hydrogels followed pseudo-second-order kinetic model and sepia ink improved adsorption capacity significantly. The adsorption capacity at equilibrium was increased from 53.72 to 138.25mg/g when the additive amount of sepia ink of the hydrogels was 10%. PMID:27185109

  12. Silicone-based tough hydrogels with high resilience, fast self-recovery, and self-healing properties.

    PubMed

    Si, Liqi; Zheng, Xiaowen; Nie, Jun; Yin, Ruixue; Hua, Yujie; Zhu, Xiaoqun

    2016-06-28

    Tough hydrogels are prepared from two monomers via photopolymerization of hydroxyethyl acrylate and sol-gel of methyltrimethoxysilane. Constitution and water content could be tuned easily because of the good water solubility of both monomers and two non-interfering polymerization processes. The hydrogels exhibit excellent integrated performance with toughness, high resilience, fast self-recovery, and self-healing. PMID:27257636

  13. Performance of an in situ formed bioactive hydrogel dressing from a PEG-based hyperbranched multifunctional copolymer.

    PubMed

    Dong, Yixiao; Hassan, Waqar U; Kennedy, Robert; Greiser, Udo; Pandit, Abhay; Garcia, Yolanda; Wang, Wenxin

    2014-05-01

    Hydrogel dressings have been widely used for wound management due to their ability to maintain a hydrated wound environment, restore the skin's physical barrier and facilitate regular dressing replacement. However, the therapeutic functions of standard hydrogel dressings are restricted. In this study, an injectable hybrid hydrogel dressing system was prepared from a polyethylene glycol (PEG)-based thermoresponsive hyperbranched multiacrylate functional copolymer and thiol-modified hyaluronic acid in combination with adipose-derived stem cells (ADSCs). The cell viability, proliferation and metabolic activity of the encapsulated ADSCs were studied in vitro, and a rat dorsal full-thickness wound model was used to evaluate this bioactive hydrogel dressing in vivo. It was found that long-term cell viability could be achieved for both in vitro (21days) and in vivo (14days) studies. With ADSCs, this hydrogel system prevented wound contraction and enhanced angiogenesis, showing the potential of this system as a bioactive hydrogel dressing for wound healing.

  14. Performance of an in situ formed bioactive hydrogel dressing from a PEG-based hyperbranched multifunctional copolymer.

    PubMed

    Dong, Yixiao; Hassan, Waqar U; Kennedy, Robert; Greiser, Udo; Pandit, Abhay; Garcia, Yolanda; Wang, Wenxin

    2014-05-01

    Hydrogel dressings have been widely used for wound management due to their ability to maintain a hydrated wound environment, restore the skin's physical barrier and facilitate regular dressing replacement. However, the therapeutic functions of standard hydrogel dressings are restricted. In this study, an injectable hybrid hydrogel dressing system was prepared from a polyethylene glycol (PEG)-based thermoresponsive hyperbranched multiacrylate functional copolymer and thiol-modified hyaluronic acid in combination with adipose-derived stem cells (ADSCs). The cell viability, proliferation and metabolic activity of the encapsulated ADSCs were studied in vitro, and a rat dorsal full-thickness wound model was used to evaluate this bioactive hydrogel dressing in vivo. It was found that long-term cell viability could be achieved for both in vitro (21days) and in vivo (14days) studies. With ADSCs, this hydrogel system prevented wound contraction and enhanced angiogenesis, showing the potential of this system as a bioactive hydrogel dressing for wound healing. PMID:24389319

  15. Photo-actuating waveguiding fibers based on light responsive hydrogels

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Hauser, Adam; Rasmussen, Nathan; Kuzyk, Mark; Hayward, Ryan

    2015-03-01

    The combination of light-absorbing nanoparticles with thermally sensitive hydrogels has been widely explored as a strategy for photo-thermal actuation. Here, we employ a system of photo-crosslinkable copolymers containing pendent benzophenone units to prepare planar waveguiding polymethylmethacrylate(PMMA) fibers patterned with poly(N-isopropyl acrylamide) (PNIPAM) copolymer hydrogels containing Au nanoparticles. These structures show both thermally- and photo-actuated bending behavior due to swelling stresses developed in the PNIPAM gel layer. Further, we establish that light can be successfully guided into micro-patterned fibers, yielding a route to remotely controlled micro-actuators.

  16. Thermosensitive injectable hyaluronic acid hydrogel for adipose tissue engineering.

    PubMed

    Tan, Huaping; Ramirez, Christina M; Miljkovic, Natasa; Li, Han; Rubin, J Peter; Marra, Kacey G

    2009-12-01

    A series of thermosensitive copolymer hydrogels, aminated hyaluronic acid-g-poly(N-isopropylacrylamide) (AHA-g-PNIPAAm), were synthesized by coupling carboxylic end-capped PNIPAAm (PNIPAAm-COOH) to AHA through amide bond linkages. AHA was prepared by grafting adipic dihydrazide to the HA backbone and PNIPAAm-COOH copolymer was synthesized via a facile thermo-radical polymerization technique by polymerization of NIPAAm using 4,4'-azobis(4-cyanovaleric acid) as an initiator, respectively. The structure of AHA and AHA-g-PNIPAAm copolymer was determined by (1)H NMR. Two AHA-g-PNIPAAm copolymers with different weight ratios of PNIPAAm on the applicability of injectable hydrogels were characterized. The lower critical solution temperature (LCST) of AHA-g-PNIPAAm copolymers in PBS were measured as approximately 30 degrees C by rheological analysis, regardless of the grafting degrees. Enzymatic resistance of AHA-g-PNIPAAm hydrogels with 28% and 53% of PNIPAAm in 100U/mL hyaluronidase/PBS at 37 degrees C was 12.3% and 37.6% over 28 days, respectively. Equilibrium swelling ratios of AHA-g-PNIPAAm hydrogels with 28% of PNIPAAm were 21.5, and significantly decreased to 13.3 with 53% of PNIPAAm in PBS at 37 degrees C. Results from SEM observations confirm a porous 3D AHA-g-PNIPAAm hydrogel structure with interconnected pores after freeze-drying and the pore diameter depends on the weight ratios of PNIPAAm. Encapsulation of human adipose-derived stem cells (ASCs) within hydrogels showed the AHA-g-PNIPAAm copolymers were noncytotoxic and preserved the viability of the entrapped cells. A preliminary in vivo study demonstrated the usefulness of the AHA-g-PNIPAAm copolymer as an injectable hydrogel for adipose tissue engineering. This newly described thermoresponsive AHA-g-PNIPAAm copolymer demonstrated attractive properties to serve as cell or pharmaceutical delivery vehicles for a variety of tissue engineering applications. PMID:19783043

  17. Thermosensitive injectable hyaluronic acid hydrogel for adipose tissue engineering

    PubMed Central

    Tan, Huaping; Ramirez, Christina M.; Miljkovic, Natasa; Li, Han; Rubin, J. Peter; Marra, Kacey G.

    2009-01-01

    A series of thermosensitive copolymer hydrogels, aminated hyaluronic acid-g-poly(N-isopropylacrylamide) (AHA-g-PNIPAAm), were synthesized by coupling carboxylic end-capped PNIPAAm (PNIPAAm-COOH) to AHA through amide bond linkages. AHA was prepared by grafting adipic dihydrazide to the HA backbone and PNIPAAm-COOH copolymer was synthesized via a facile thermo-radical polymerization technique by polymerization of NIPAAm using 4,4′-azobis(4-cyanovaleric acid) as an initiator, respectively. The structure of AHA and AHA-g-PNIPAAm copolymer was determined by 1H NMR. Two AHA-g-PNIPAAm copolymers with different weight ratios of PNIPAAm on the applicability of injectable hydrogels were characterized. The lower critical solution temperature (LCST) of AHA-g-PNIPAAm copolymers in PBS were measured as ~30°C by rheological analysis, regardless of the grafting degrees. Enzymatic resistance of AHA-g-PNIPAAm hydrogels with 28% and 53% of PNIPAAm in 100U/mL hyaluronidase/PBS at 37°C was 12.3% and 37.6% over 28 days, respectively. Equilibrium swelling ratios of AHA-g-PNIPAAm hydrogels with 28% of PNIPAAm were 21.5, and significantly decreased to 13.3 with 53% of PNIPAAm in PBS at 37°C. Results from SEM observations confirm a porous 3D AHA-g-PNIPAAm hydrogel structure with interconnected pores after freeze-drying and the pore diameter depends on the weight ratios of PNIPAAm. Encapsulation of human adipose-derived stem cells (ASCs) within hydrogels showed the AHA-g-PNIPAAm copolymers were noncytotoxic and preserved the viability of the entrapped cells. A preliminary in vivo study demonstrated the usefulness of the AHA-g-PNIPAAm copolymer as an injectable hydrogel for adipose tissue engineering. This newly described thermoresponsive AHA-g-PNIPAAm copolymer demonstrated attractive properties to serve as cell or pharmaceutical delivery vehicles for a variety of tissue engineering applications. PMID:19783043

  18. Rheological behavior and Ibuprofen delivery applications of pH responsive composite alginate hydrogels.

    PubMed

    Jabeen, Suraya; Maswal, Masrat; Chat, Oyais Ahmad; Rather, Ghulam Mohammad; Dar, Aijaz Ahmad

    2016-03-01

    Synthesis and structural characterization of hydrogels composed of sodium alginate, polyethylene oxide and acrylic acid with cyclodextrin as the hydrocolloid prepared at different pH values is presented. The hydrogels synthesized show significant variations in rheological properties, drug encapsulation capability and release kinetics. The hydrogels prepared at lower pH (pH 1) are more elastic, have high tensile strength and remain almost unaffected by varying temperature or frequency. Further, their Ibuprofen encapsulation capacity is low and releases it slowly. The hydrogel prepared at neutral pH (pH 7) is viscoelastic, thermo-reversible and also exhibits sol-gel transition on applying frequency and changing temperature. It shows highest Ibuprofen encapsulation capacity and also optimum drug release kinetics. The hydrogel prepared at higher pH (pH 12) is more viscous, has low tensile strength, is unstable to change in temperature and has fast drug release rate. The study highlights the pH responsiveness of three composite alginate hydrogels prepared under different conditions to be employed in drug delivery applications. PMID:26717508

  19. Enzyme actuated bioresponsive hydrogels

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew Nolan

    Bioresponsive hydrogels are emerging with technological significance in targeted drug delivery, biosensors and regenerative medicine. Conferred with the ability to respond to specific biologically derived stimuli, the design challenge is in effectively linking the conferred biospecificity with an engineered response tailored to the needs of a particular application. Moreover, the fundamental phenomena governing the response must support an appropriate dynamic range and limit of detection. The design of these systems is inherently complicated due to the high interdependency of the governing phenomena that guide the sensing, transduction, and the actuation response of hydrogels. To investigate the dynamics of these materials, model systems may be used which seek to interrogate the system dynamics by uni-variable experimentation and limit confounding phenomena such as: polymer-solute interactions, polymer swelling dynamics and biomolecular reaction-diffusion concerns. To this end, a model system, alpha-chymotrypsin (Cht) (a protease) and a cleavable peptide-chromogen (pro-drug) covalently incorporated into a hydrogel, was investigated to understand the mechanisms of covalent loading and release by enzymatic cleavage in bio-responsive delivery systems. Using EDC and Sulfo-NHS, terminal carboxyl groups of N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide, a cleavable chromogen, were conjugated to primary amines of a hydrated poly(HEMA)-based hydrogel. Hydrogel discs were incubated in buffered Cht causing enzyme-mediated cleavage of the peptide and concomitant release of the chromophore for monitoring. To investigate substrate loading and the effects of hydrogel morphology on the system, the concentration of the amino groups (5, 10, 20, and 30 mol%) and the cross-linked density (1, 5, 7, 9 and 12 mol%) were independently varied. Loading-Release Efficiency of the chromogen was shown to exhibit a positive relation to increasing amino groups (AEMA). The release rates demonstrated a

  20. Magnetically aligned supramolecular hydrogels.

    PubMed

    Wallace, Matthew; Cardoso, Andre Zamith; Frith, William J; Iggo, Jonathan A; Adams, Dave J

    2014-12-01

    The magnetic-field-induced alignment of the fibrillar structures present in an aqueous solution of a dipeptide gelator, and the subsequent retention of this alignment upon transformation to a hydrogel upon the addition of CaCl2 or upon a reduction in solution pH is reported. Utilising the switchable nature of the magnetic field coupled with the slow diffusion of CaCl2 , it is possible to precisely control the extent of anisotropy across a hydrogel, something that is generally very difficult to do using alternative methods. The approach is readily extended to other compounds that form viscous solutions at high pH. It is expected that this work will greatly expand the utility of such low-molecular-weight gelators (LMWG) in areas where alignment is key. PMID:25345918

  1. Neovascularization within porous PEG hydrogels

    NASA Astrophysics Data System (ADS)

    Chiu, Yu-Chieh

    The goal of this work described was to develop techniques that can be used to enhance vascularized tissue formation in PEG-based hydrogels. In the first part of the study a technique was developed to generate porous PEG hydrogels using a salt leaching technique. This technique was then used to examine the role of pore size on vascularization and tissue remodeling in porous PEG hydrogel in vitro and in vitro. Both in vitro and in vivo studies showed that vessel invasion was pore size dependent. In addition, a thin layer of inflammatory tissue was observed between PEG hydrogel and blood vessels that formed within the gels. The porous PEG hydrogels were very stable in vitro and in vivo and did not exhibit any signs of degradation. Hydrogels used in tissue engineering need to exhibit controlled degradation. In order to address the stability of PEG hydrogels, porous hydrogels were rendered using degradable PEG-co-(L-Lactic acid) diacrylate PEG-PLLA-DA. This polymer is degraded via hydrolysis of the PLLA chains. The hydrogels were found to exhibit autofluorescence that allowed for the unique ability to nondestructively image hydrogel structure under fully swelled conditions using confocal microscopy. Interestingly, pore size remained stable though out the study, and was not a function of degradation. In addition, degradation time of porous PEG-LLA-DA hydrogels was influenced by polymer concentration. Compressive modulus was a function of polymer concentration and pore size and decreased during hydrogel degradation. The incorporation of cell adhesion sequences into the hydrogel showed that they can support cell adhesion with morphology varying with pore size. This technique could be used to tailor porous biodegradable scaffolds for tissue engineering applications. In the final portion of this thesis a poly-lysine (PLL) molecule was synthesized in order to allow clustering of adhesion sequences in PEG hydrogels. Clusters of peptide sequences have been shown to enhance cell

  2. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets.

    PubMed

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

  3. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets

    NASA Astrophysics Data System (ADS)

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions.

  4. An anisotropic hydrogel with electrostatic repulsion between cofacially aligned nanosheets.

    PubMed

    Liu, Mingjie; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Takata, Masaki; Aida, Takuzo

    2015-01-01

    Machine technology frequently puts magnetic or electrostatic repulsive forces to practical use, as in maglev trains, vehicle suspensions or non-contact bearings. In contrast, materials design overwhelmingly focuses on attractive interactions, such as in the many advanced polymer-based composites, where inorganic fillers interact with a polymer matrix to improve mechanical properties. However, articular cartilage strikingly illustrates how electrostatic repulsion can be harnessed to achieve unparalleled functional efficiency: it permits virtually frictionless mechanical motion within joints, even under high compression. Here we describe a composite hydrogel with anisotropic mechanical properties dominated by electrostatic repulsion between negatively charged unilamellar titanate nanosheets embedded within it. Crucial to the behaviour of this hydrogel is the serendipitous discovery of cofacial nanosheet alignment in aqueous colloidal dispersions subjected to a strong magnetic field, which maximizes electrostatic repulsion and thereby induces a quasi-crystalline structural ordering over macroscopic length scales and with uniformly large face-to-face nanosheet separation. We fix this transiently induced structural order by transforming the dispersion into a hydrogel using light-triggered in situ vinyl polymerization. The resultant hydrogel, containing charged inorganic structures that align cofacially in a magnetic flux, deforms easily under shear forces applied parallel to the embedded nanosheets yet resists compressive forces applied orthogonally. We anticipate that the concept of embedding anisotropic repulsive electrostatics within a composite material, inspired by articular cartilage, will open up new possibilities for developing soft materials with unusual functions. PMID:25557713

  5. Synchronizing nonfouling and antimicrobial properties in a zwitterionic hydrogel.

    PubMed

    Mi, Luo; Jiang, Shaoyi

    2012-12-01

    In this work, we report a new approach to integrate antimicrobial and nonfouling properties into a single platform without compromising each other. To achieve this, a zwitterionic hydrogel is conjugated with an antimicrobial agent as a leaving group in a way that maintains the zwitterionic form of the hydrogel before, during and after drug release, preventing bacteria surface adhesion and bulk proliferation simultaneously. The antibacterial salicylate anion contributes the negative charge to the initial zwitterionic state and is released through the ester linkage hydrolysis. The hydrogel then switches to its final zwitterionic state with the carboxylate as its new negatively charged group. We prove that this hydrogel can reach one-salicylate-per-monomer drug loading while still retaining the nonfouling property at protein and bacteria levels. It was also shown that its drug release profile was dictated by the hydrolysis rate of the monomer, making it possible to control and tailor the release rate of small hydrophilic drugs from the highly hydrated nonfouling polymer matrix.

  6. Gelatin Effects on the Physicochemical and Hemocompatible Properties of Gelatin/PAAm/Laponite Nanocomposite Hydrogels.

    PubMed

    Li, Changpeng; Mu, Changdao; Lin, Wei; Ngai, To

    2015-08-26

    In recent years, inorganic nanoparticles such as Laponite have frequently been incorporated into polymer matrixes to obtain nanocomposite hydrogels with hierarchical structures, ultrastrong tensibilities, and high transparencies. Despite their unique physical and chemical properties, only a few reports have evaluated Laponite-based nanocomposite hydrogels for biomedical applications. This article presents the synthesis and characterization of a novel, hemocompatible nanocomposite hydrogels by in situ polymerization of acrylamide (AAm) in a mixed suspension containing Laponite and gelatin. The compatibility, structure, thermal stability, and mechanical properties of the resulting NC gels with varied gel compositions were investigated. Our results show that the prepared nanocomposite hydrogels exhibit good thermal stability and mechanical properties. The introduction of a biocompatible polymer, gelatin, into the polymer matrix did not change the transparency and homogeneity of the resulting nanocomposite hydrogels, but it significantly decreased the hydrogel's pH-responsive properties. More importantly, gelatins that were incorporated into the PAAm network resisted nonspecific protein adsorption, improved the degree of hemolysis, and eventually prolonged the clotting time, indicating that the in vitro hemocompatibility of the resulting nanocomposite hydrogels had been substantially enhanced. Therefore, these nanocomposite hydrogels provide opportunities for potential use in various biomedical applications.

  7. Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

    PubMed

    Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

    2014-07-17

    A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel. PMID:24702940

  8. A novel multi-responsive polyampholyte composite hydrogel with excellent mechanical strength and rapid shrinking rate.

    PubMed

    Xu, Kun; Tan, Ying; Chen, Qiang; An, Huiyong; Li, Wenbo; Dong, Lisong; Wang, Pixin

    2010-05-15

    Series of hydrophilic core-shell microgels with cross-linked poly(N-isopropylacrylamide) (PNIPAAm) as core and poly(vinyl amine) (PVAm) as shell are synthesized via surfactant-free emulsion polymerization. Then, the microgels are treated with a small amount of potassium persulfate (KPS) to generate free radicals on the amine nitrogens of PVAm, which subsequently initiate the graft copolymerization of acrylic acid (AA), acryloyloxyethyl trimethyl ammonium chloride (DAC), and acrylamide (AAm) onto microgels to prepare multi-responsive composite hydrogels. The composite hydrogels consist of cross-linked ungrafted polyampholyte chains as the first network and microgels with grafted polyampholyte chains as graft point and second network and show surprising mechanical strength and rapid response rate. The investigation shows the compress strength of composite hydrogels is up to 17-30 MPa, which is 60-100 times higher than that of the hydrogel matrix. The composite hydrogel shows reversible switch of transmittance when traveling the lowest critical temperature (LCST) of microgels. When the composite hydrogel swollen in pH 2.86 solution at ambient condition is immersed into the pH 7.00 solution at 45 °C, a rapid dynamic shrinking can be observed. And the character time (τ) of shrinking dynamic of composite hydrogel is 251.9 min, which is less than that of hydrogel matrix (τ=2273.7 min). PMID:20152987

  9. Gelatin Effects on the Physicochemical and Hemocompatible Properties of Gelatin/PAAm/Laponite Nanocomposite Hydrogels.

    PubMed

    Li, Changpeng; Mu, Changdao; Lin, Wei; Ngai, To

    2015-08-26

    In recent years, inorganic nanoparticles such as Laponite have frequently been incorporated into polymer matrixes to obtain nanocomposite hydrogels with hierarchical structures, ultrastrong tensibilities, and high transparencies. Despite their unique physical and chemical properties, only a few reports have evaluated Laponite-based nanocomposite hydrogels for biomedical applications. This article presents the synthesis and characterization of a novel, hemocompatible nanocomposite hydrogels by in situ polymerization of acrylamide (AAm) in a mixed suspension containing Laponite and gelatin. The compatibility, structure, thermal stability, and mechanical properties of the resulting NC gels with varied gel compositions were investigated. Our results show that the prepared nanocomposite hydrogels exhibit good thermal stability and mechanical properties. The introduction of a biocompatible polymer, gelatin, into the polymer matrix did not change the transparency and homogeneity of the resulting nanocomposite hydrogels, but it significantly decreased the hydrogel's pH-responsive properties. More importantly, gelatins that were incorporated into the PAAm network resisted nonspecific protein adsorption, improved the degree of hemolysis, and eventually prolonged the clotting time, indicating that the in vitro hemocompatibility of the resulting nanocomposite hydrogels had been substantially enhanced. Therefore, these nanocomposite hydrogels provide opportunities for potential use in various biomedical applications. PMID:26202134

  10. Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

    PubMed Central

    Lian, Sheng; Xiao, Yan; Bian, Qingqing; Xia, Yu; Guo, Changfa; Wang, Shenguo; Lang, Meidong

    2012-01-01

    A series of biodegradable thermosensitive copolymers was synthesized by free radical polymerization with N-isopropylacrylamide (NIPAAm), acrylic acid (AAc) and macromer 2-hydroxylethyl methacrylate-poly(ɛ-caprolactone) (HEMAPCL). The structure and composition of the obtained terpolymers were confirmed by proton nuclear magnetic resonance spectroscopy, while their molecular weight was measured using gel permeation chromatography. The copolymers were dissolved in phosphate-buffered saline (PBS) solution (pH = 7.4) with different concentrations to prepare hydrogels. The lower critical solution temperature (LCST), cloud point, and rheological property of the hydrogels were determined by differential scanning calorimetry, ultraviolet-visible spectrometry, and rotational rheometry, respectively. It was found that LCST of the hydrogel increased significantly with the increasing NIPAAm content, and hydrogel with higher AAc/HEMAPCL ratio exhibited better storage modulus, water content, and injectability. The hydrogels were formed by maintaining the copolymer solution at 37°C. The degradation experiment on the formed hydrogels was conducted in PBS solution for 2 weeks and demonstrated a less than 20% weight loss. Scanning electron microscopy was also used to study the morphology of the hydrogel. The copolymer with NIPAAm/AAc/HEMAPCL ratio of 88:9.6:2.4 was bioconjugated with type I collagen for the purpose of biocompatibility enhancement. In-vitro cytotoxicity of the hydrogels both with and without collagen was also addressed. PMID:23028218

  11. Two-dimensional inverse opal hydrogel for pH sensing.

    PubMed

    Xue, Fei; Meng, Zihui; Qi, Fenglian; Xue, Min; Wang, Fengyan; Chen, Wei; Yan, Zequn

    2014-12-01

    A novel hydrogel film with a highly ordered macropore monolayer on its surface was prepared by templated photo-polymerization of hydrogel monomers on a two-dimensional (2D) polystyrene colloidal array. The 2D inverse opal hydrogel has prominent advantages over traditional three-dimensional (3D) inverse opal hydrogels. First, the formation of the 2D array template through a self-assembly method is considerably faster and simpler. Second, the stable ordering structure of the 2D array template makes it easier to introduce the polymerization solution into the template. Third, a simple measurement, a Debye diffraction ring, is utilized to characterize the neighboring pore spacing of the 2D inverse opal hydrogel. Acrylic acid was copolymerized into the hydrogel; thus, the hydrogel responded to pH through volume change, which resulted from the formation of the Donnan potential. The 2D inverse opal hydrogel showed that the neighboring pore spacing increased by about 150 nm and diffracted color red-shifted from blue to red as the pH increased from pH 2 to 7. In addition, the pH response kinetics and ionic strength effect of this 2D mesoporous polymer film were also investigated. PMID:25292208

  12. Comparison of two hydrogel formulations for drug release in ophthalmic lenses.

    PubMed

    Paradiso, P; Galante, R; Santos, L; Alves de Matos, A P; Colaço, R; Serro, A P; Saramago, B

    2014-08-01

    In the present work two types of polymers were investigated as drug releasing contact lens materials: a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel and a silicone hydrogel. The silicone hydrogel resulted from the addition of TRIS, a hydrophobic monomer containing silicon (3-tris(trimethylsilyloxy)silylpropyl 2-methylprop-2-enoate), to pHEMA. Both hydrogels were loaded with an antibiotic (levofloxacin) and an antiseptic (chlorhexidine) by soaking in the drug solutions. The hydrogel properties were determined to be within the range demanded for lens materials. The release profiles of both drugs from the hydrogels were obtained and eventual drug/polymer interactions were assessed with the help of Raman spectra. A mathematical model, developed to mimic the eye conditions, was applied to the experimental results in order to predict the in vivo efficacy of the studied systems. The release profiles were compared with those resulting from the application of commercial eyedrops. The pHEMA based hydrogel demonstrated to be the best material to achieve a controlled release of levofloxacin. In the case of chlorhexidine, the silicone hydrogel seems to lead to better results. In both cases, our results suggest that these materials are adequate for the preparation of daily disposable therapeutic contact lenses. PMID:24408887

  13. Injectable thermosensitive chitosan hydrogels with controlled gelation kinetics and enhanced mechanical resistance.

    PubMed

    Assaad, Elias; Maire, Marion; Lerouge, Sophie

    2015-10-01

    The use of injectable hydrogels is presently limited by the difficulty to achieve rapid gelation, high mechanical resistance and excellent cytocompatibility. In our study, high-strength injectable thermosensitive hydrogels of unmodified chitosan (CH) were obtained by combining sodium hydrogen carbonate (SHC) with phosphate buffer (PB) or beta-glycerophosphate (BGP) as gelling agents. A synergic effect led to the acceleration of gelation and a remarkable improvement of the storage modulus (G') of the hydrogels. Furthermore, the new hydrogels exhibited drastically enhanced Young moduli and resistance in compression as compared to conventional hydrogels prepared with BGP, PB or their combination. This was achieved while reducing the total salt concentration in the hydrogels. The gelation was rapid and the hydrogels presented porous structures and physiological pH, and did not show any cytotoxicity to L929 fibroblast cells in vitro. Overall, these new hydrogels provide interesting alternatives for use as blood vessel embolizing agents or as injectable scaffolds for drug delivery and/or cell seeding in tissue engineering strategies.

  14. Sulfoacetic acid modifying poly(vinyl alcohol) hydrogel and its electroresponsive behavior under DC electric field

    NASA Astrophysics Data System (ADS)

    Xiang, Yu; Liu, Genqi; Zhang, Cheng; Liao, Jiae

    2013-01-01

    A strong electrolyte hydrogel was prepared by modifying poly (vinyl alcohol) hydrogel with sulfoacetic acid (SA-PVA). Its swelling properties, mechanical properties, and electroresponsive behavior in Na2SO4 solutions were studied. The results indicated that the water take-up ability of the hydrogel decreased with the increasing ionic strength of Na2SO4 solution. The Young’s modulus, elongation at break and tensile strength of the hydrogel swollen in deionized water are 1.247 MPa, 187% and 2.2 MPa, respectively. The hydrogel swollen in a Na2SO4 solution bent towards the cathode under non-contact dc electric fields, and its bending speed and equilibrium strain increased with increasing applied voltage. There is a critical ionic strength of 0.03 at which the maximum equilibrium strain of the hydrogel occurs. Also the bending behavior of hydrogel was not affected by the pH changes. By altering the direction of the applied potential cyclically, the hydrogel exhibited good reversible bending behavior. On this basis, a gel-worm was designed. Under a cyclically varying electric field (the period was 8 s, and the voltage ranged from -10 to 10 V), the walking speed was up to 15 cm min-1 in Na2SO4 solution with an ionic strength of 0.03.

  15. Dual-responsive shape memory hydrogels with novel thermoplasticity based on a hydrophobically modified polyampholyte.

    PubMed

    Fan, Yujiao; Zhou, Wanfu; Yasin, Akram; Li, Huazhen; Yang, Haiyang

    2015-06-01

    Shape memory hydrogels offer the ability to recover their permanent shape from temporarily trapped shapes without application of external forces. Here, we report a novel dual-responsive shape memory hydrogel with characteristic thermoplasticity. The water-insoluble hydrogel is prepared by simple ternary copolymerization of acrylamide (AM) and acrylic acid (AA) with low amounts of a cationic surfmer, in the absence of organic crosslinkers. Through either ionic/complex binding of carboxyl groups via trivalent cations or salt-dependent hydrophobic association, the hydrogel can memorize a temporary shape successfully, which recovers its permanent form in the presence of a reducing agent or deionized water. Besides, the unique thermoplasticity of the hydrophobic polyampholyte hydrogel allows the change of its permanent shape upon heating and the fixation after cooling, which is in strong contrast to the conventional chemically cross-linked shape memory hydrogels. This fascinating feature undoubtedly enriches the shape memory hydrogel systems. Thus, we believe that the facile strategy could provide new opportunities with regard to the design and practical application of stimulus-responsive hydrogel systems.

  16. Two-dimensional inverse opal hydrogel for pH sensing.

    PubMed

    Xue, Fei; Meng, Zihui; Qi, Fenglian; Xue, Min; Wang, Fengyan; Chen, Wei; Yan, Zequn

    2014-12-01

    A novel hydrogel film with a highly ordered macropore monolayer on its surface was prepared by templated photo-polymerization of hydrogel monomers on a two-dimensional (2D) polystyrene colloidal array. The 2D inverse opal hydrogel has prominent advantages over traditional three-dimensional (3D) inverse opal hydrogels. First, the formation of the 2D array template through a self-assembly method is considerably faster and simpler. Second, the stable ordering structure of the 2D array template makes it easier to introduce the polymerization solution into the template. Third, a simple measurement, a Debye diffraction ring, is utilized to characterize the neighboring pore spacing of the 2D inverse opal hydrogel. Acrylic acid was copolymerized into the hydrogel; thus, the hydrogel responded to pH through volume change, which resulted from the formation of the Donnan potential. The 2D inverse opal hydrogel showed that the neighboring pore spacing increased by about 150 nm and diffracted color red-shifted from blue to red as the pH increased from pH 2 to 7. In addition, the pH response kinetics and ionic strength effect of this 2D mesoporous polymer film were also investigated.

  17. Hydrogels of collagen/chondroitin sulfate/hyaluronan interpenetrating polymer network for cartilage tissue engineering.

    PubMed

    Guo, Yan; Yuan, Tun; Xiao, Zhanwen; Tang, Pingping; Xiao, Yumei; Fan, Yujiang; Zhang, Xingdong

    2012-09-01

    The network structure of a three-dimensional hydrogel scaffold dominates its performance such as mechanical strength, mass transport capacity, degradation rate and subsequent cellular behavior. The hydrogels scaffolds with interpenetrating polymeric network (IPN) structure have an advantage over the individual component gels and could simulate partly the structure of native extracellular matrix of cartilage tissue. In this study, to develop perfect cartilage tissue engineering scaffolds, IPN hydrogels of collagen/chondroitin sulfate/hyaluronan were prepared via two simultaneous processes of collagen self-assembly and cross linking polymerization of chondroitin sulfate-methacrylate (CSMA) and hyaluronic acid-methacrylate. The degradation rate, swelling performance and compressive modulus of IPN hydrogels could be adjusted by varying the degree of methacrylation of CSMA. The results of proliferation and fluorescence staining of rabbit articular chondrocytes in vitro culture demonstrated that the IPN hydrogels possessed good cytocompatibility. Furthermore, the IPN hydrogels could upregulate cartilage-specific gene expression and promote the chondrocytes secreting glycosaminoglycan and collagen II. These results suggested that IPN hydrogels might serve as promising hydrogel scaffolds for cartilage tissue engineering. PMID:22639153

  18. Comparison of two hydrogel formulations for drug release in ophthalmic lenses.

    PubMed

    Paradiso, P; Galante, R; Santos, L; Alves de Matos, A P; Colaço, R; Serro, A P; Saramago, B

    2014-08-01

    In the present work two types of polymers were investigated as drug releasing contact lens materials: a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel and a silicone hydrogel. The silicone hydrogel resulted from the addition of TRIS, a hydrophobic monomer containing silicon (3-tris(trimethylsilyloxy)silylpropyl 2-methylprop-2-enoate), to pHEMA. Both hydrogels were loaded with an antibiotic (levofloxacin) and an antiseptic (chlorhexidine) by soaking in the drug solutions. The hydrogel properties were determined to be within the range demanded for lens materials. The release profiles of both drugs from the hydrogels were obtained and eventual drug/polymer interactions were assessed with the help of Raman spectra. A mathematical model, developed to mimic the eye conditions, was applied to the experimental results in order to predict the in vivo efficacy of the studied systems. The release profiles were compared with those resulting from the application of commercial eyedrops. The pHEMA based hydrogel demonstrated to be the best material to achieve a controlled release of levofloxacin. In the case of chlorhexidine, the silicone hydrogel seems to lead to better results. In both cases, our results suggest that these materials are adequate for the preparation of daily disposable therapeutic contact lenses.

  19. Injectable oxidized hyaluronic acid/adipic acid dihydrazide hydrogel for nucleus pulposus regeneration.

    PubMed

    Su, Wen-Yu; Chen, Yu-Chun; Lin, Feng-Huei

    2010-08-01

    Injectable hydrogel allows irregular surgical defects to be completely filled, lessens the risk of implant migration, and minimizes surgical defects due to the solution-gel state transformation. Here, we first propose a method for preparing oxidized hyaluronic acid/adipic acid dihydrazide (oxi-HA/ADH) injectable hydrogel by chemical cross-linking under physiological conditions. Fourier transform infrared spectrometry and trinitrobenzene sulfonate assay were used to confirm the oxidation of hyaluronic acid. Rheological properties were measured to evaluate the working ability of the hydrogel for further clinical application. The oxi-HA/ADH in situ forming hydrogel can transform from liquid form into a gel-like matrix within 3-8 min, depending on the operational temperature. Furthermore, hydrogel degradation and cell assessment is also a concern for clinical application. Injectable oxi-HA/ADH8 hydrogel can maintain its gel-like state for at least 5 weeks with a degradation percentage of 40%. Importantly, oxi-HA/ADH8 hydrogel can assist in nucleus pulposus cell synthesis of type II collagen and aggrecan mRNA gene expression according to the results of real-time PCR analysis, and shows good biocompatibility based on cell viability and cytotoxicity assays. Based on the results of the current study, oxi-HA/ADH hydrogel may possess several advantages for future application in nucleus pulposus regeneration. PMID:20193782

  20. Synthesis and properties of waterborne polyurethane hydrogels for wound healing dressings.

    PubMed

    Yoo, Hye-Jin; Kim, Han-Do

    2008-05-01

    To accomplish ideal wound healing dressing, a series of waterborne polyurethane (WBPU) hydrogels based on polyethylene glycol (PEG) were synthesized by polyaddition reaction in an emulsion system. The stable WBPU hydrogels which have remaining weight of above 85% were obtained. The effect of the soft segment (PEG) content on water absorbability of WBPU hydrogels was investigated. Water absorption % and equilibrium water content (%) of the WBPU hydrogel significantly increased in proportion to PEG content and the time of water-immersion. The maximum water absorption % and equilibrium water content (%) of WBPU hydrogels containing various PEG contents were in the range of 409-810% and 85-96%, respectively. The water vapor transmission rate of the WBPU hydrogels was found to be in the range of 1490-3118 g/m(2)/day. These results suggest that the WBPU hydrogels prepared in this study may have high potential as new wound dressing materials, which provide and maintain the adequate moist environment required to prevent scab formation and dehydration of the wound bed. By the wound healing evaluation using full-thickness rat model experiment, it was found that the wound covered with a typical WBPU hydrogel (HG-78 sample) was completely filled with new epithelium without any significant adverse reactions. PMID:17973247

  1. Self-healable hydrogel on tumor cell as drug delivery system for localized and effective therapy.

    PubMed

    Chang, Guanru; Chen, Yan; Li, Yanjie; Li, Shikuo; Huang, Fangzhi; Shen, Yuhua; Xie, Anjian

    2015-05-20

    A self-healable chitosan(CS)/polyvinyl alcohol (PVA) hydrogel as an injectable drug carrier was first prepared in situ on tumor cells for effective and localized therapy. PVA molecules have a synergistic effect on the formation and maintenance of 3D network conformation of hydrogel. The hydrogel shows good biocompatibility and could be easily and rapidly formed. When loaded with fluorouracil (5-FU), the hydrogel possessed good drug retention ability at pH 7.4, which can prevent the loss of drug to normal cells and reduce the side effect. As well, the hydrogel shows continuous and controllable drug release, with the final cumulative releasing amount of 84.8% at pH 5.0. Therefore, the hydrogel not only could maintain a higher 5-FU concentration around tumor cells to enhance the antitumor effect, but also can achieve pH sensitive controllable drug release at the lesion site. Meantime, the attractive self-healing ability of the CS/PVA hydrogel is first revealed in this study, which contributes to the regeneration of its integral network from the broken fragments. The CS/PVA hydrogel may hold promise for better applications in anti-tumor therapy.

  2. Non-cytotoxic, In Situ Gelable Hydrogels Composed of N-carboxyethyl Chitosan and Oxidized Dextran

    PubMed Central

    Weng, Lihui; Romanov, Alexander; Rooney, Jean; Chen, Weiliam

    2008-01-01

    A series of in situ gelable hydrogels were prepared from oxidized dextran (Odex) and N-carboxyethyl chitosan (CEC) without any extraneous crosslinking agent. The gelation readily took place at physiological pH and body temperature. The gelation process was monitored rheologically, and the effect of the oxidation degree of dextran on the gelation process was investigated. The higher the oxidation degree of Odex, the faster the gelation. A highly porous hydrogel structure was revealed under scanning electron microscopy (SEM). Swelling and degradation of the Odex/CEC hydrogels in PBS showed that both swelling and degradation were related to the crosslinking density of the hydrogels. In particular, the hydrogels underwent fast mass loss in the first 2 weeks, followed by a more moderate degradation. The results of long-term cell viability tests revealed that the hydrogels were non-cytotoxic. Mouse fibroblasts were encapsulated in the hydrogels and cell viability was at least 95% within 3 days following encapsulation. Furthermore, cells entrapped inside the hydrogel assumed round shape initially but they gradually adapted to the new environment and spread out to assume more spiny shapes. Additionally, the results from applying the Odex/CEC system to mice full-thickness transcutaneous wound models suggested that it was capable of enhancing wound healing. PMID:18639926

  3. Injectable oxidized hyaluronic acid/adipic acid dihydrazide hydrogel for nucleus pulposus regeneration.

    PubMed

    Su, Wen-Yu; Chen, Yu-Chun; Lin, Feng-Huei

    2010-08-01

    Injectable hydrogel allows irregular surgical defects to be completely filled, lessens the risk of implant migration, and minimizes surgical defects due to the solution-gel state transformation. Here, we first propose a method for preparing oxidized hyaluronic acid/adipic acid dihydrazide (oxi-HA/ADH) injectable hydrogel by chemical cross-linking under physiological conditions. Fourier transform infrared spectrometry and trinitrobenzene sulfonate assay were used to confirm the oxidation of hyaluronic acid. Rheological properties were measured to evaluate the working ability of the hydrogel for further clinical application. The oxi-HA/ADH in situ forming hydrogel can transform from liquid form into a gel-like matrix within 3-8 min, depending on the operational temperature. Furthermore, hydrogel degradation and cell assessment is also a concern for clinical application. Injectable oxi-HA/ADH8 hydrogel can maintain its gel-like state for at least 5 weeks with a degradation percentage of 40%. Importantly, oxi-HA/ADH8 hydrogel can assist in nucleus pulposus cell synthesis of type II collagen and aggrecan mRNA gene expression according to the results of real-time PCR analysis, and shows good biocompatibility based on cell viability and cytotoxicity assays. Based on the results of the current study, oxi-HA/ADH hydrogel may possess several advantages for future application in nucleus pulposus regeneration.

  4. Mechanically resilient, injectable, and bioadhesive supramolecular gelatin hydrogels crosslinked by weak host-guest interactions assist cell infiltration and in situ tissue regeneration.

    PubMed

    Feng, Qian; Wei, Kongchang; Lin, Sien; Xu, Zhen; Sun, Yuxin; Shi, Peng; Li, Gang; Bian, Liming

    2016-09-01

    Although considered promising materials for assisting organ regeneration, few hydrogels meet the stringent requirements of clinical translation on the preparation, application, mechanical property, bioadhesion, and biocompatibility of the hydrogels. Herein, we describe a facile supramolecular approach for preparing gelatin hydrogels with a wide array of desirable properties. Briefly, we first prepare a supramolecular gelatin macromer via the efficient host-guest complexation between the aromatic residues of gelatin and free diffusing photo-crosslinkable acrylated β-cyclodextrin (β-CD) monomers. The subsequent crosslinking of the macromers produces highly resilient supramolecular gelatin hydrogels that are solely crosslinked by the weak host-guest interactions between the gelatinous aromatic residues and β-cyclodextrin (β-CD). The obtained hydrogels are capable of sustaining excessive compressive and tensile strain, and they are capable of quick self healing after mechanical disruption. These hydrogels can be injected in the gelation state through surgical needles and re-molded to the targeted geometries while protecting the encapsulated cells. Moreover, the weak host-guest crosslinking likely facilitate the infiltration and migration of cells into the hydrogels. The excess β-CDs in the hydrogels enable the hydrogel-tissue adhesion and enhance the loading and sustained delivery of hydrophobic drugs. The cell and animal studies show that such hydrogels support cell recruitment, differentiation, and bone regeneration, making them promising carrier biomaterials of therapeutic cells and drugs via minimally invasive procedures. PMID:27294539

  5. Tough and multi-responsive hydrogel based on the hemicellulose from the spent liquor of viscose process.

    PubMed

    Du, Jian; Li, Bin; Li, Chao; Zhang, Yuedong; Yu, Guang; Wang, Haisong; Mu, Xindong

    2016-07-01

    The hemicellulose isolated from the spent liquor of a viscose process was successfully utilized to prepare hydrogels by the graft copolymerization of acrylic acid (AA) with hemicellulose. The hemicellulose and prepared hydrogel were characterized by Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), and solid-state nuclear magnetic resonance ((13)C NMR). Under the optimum preparation conditions, the highest compressive strength and strain at break of the resultant hydrogel were 105.1±12.9kPa and 34.8%, respectively. Furthermore, the maximum equilibrium swelling degree of prepared hydrogel was 192. Also, the hydrogel could rapidly respond to pH, salt and ethanol. Taken together, the prepared hydrogels had great mechanical and multi-responsive properties. Thus, the prepared hydrogels had a great potential application in drug release, water treatment and cell immobilization. In addition, the utilization of alkaline extracted hemicellulose from the viscose fiber factory has huge market potential and economic benefits. PMID:27064089

  6. A novel nanocomposite hydrogel with precisely tunable UCST and LCST.

    PubMed

    Xia, Mengge; Cheng, Yanhua; Meng, Zhouqi; Jiang, Xiaoze; Chen, Zhigang; Theato, Patrick; Zhu, Meifang

    2015-03-01

    Novel thermosensitive nanocomposite (NC) hydrogels consisting of organic/inorganic networks are prepared via in situ free radical polymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO2 MA) and oligo(ethylene glycol) methacrylate (OEGMA) in the presence of inorganic cross-linker clay in aqueous solution. The obtained clay/P(MEO2 MA-co-OEGMA) hydrogels exhibit double volume phase transition temperatures, an upper critical solution temperature (UCST), and a lower critical solution temperature (LCST), which can be controlled between 5 and 85 °C by varying the fraction of OEGMA units and the weight percentage of cross-linker clay. These new types of NC hydrogels with excellent reversible thermosensitivity are promising for temperature-sensitive applications such as smart optical switches. PMID:25611464

  7. Macroporous hydrogels with tailored morphology and mechanical properties

    NASA Astrophysics Data System (ADS)

    Bignotti, Fabio; Agnelli, Silvia; Baldi, Francesco; Sartore, Luciana; Peroni, Isabella

    2016-05-01

    In this work it is shown that hydroxyethylcellulose (HEC) can be employed for preparing macroporous polyacrylamide (PAAm) hydrogels with tailored morphology and mechanical properties. By changing the HEC content in the reaction mixture hydrogels with different pore sizes and degrees of interconnectivity can be synthesized. The equilibrium swelling ratio in 0.1 M NaCl increases with the amount of HEC employed. Tensile tests run on equilibrated hydrogels show that these materials behave as rubber-like materials. Their mechanical stiffness decreases regularly as the amount of HEC, and therefore their porosity, is increased. A more complex trend is observed for elongation and stress at break, which display a maximum at intermediate contents of HEC.

  8. Poly(2-oxazoline) hydrogels for controlled fibroblast attachment.

    PubMed

    Farrugia, Brooke L; Kempe, Kristian; Schubert, Ulrich S; Hoogenboom, Richard; Dargaville, Tim R

    2013-08-12

    Currently there is a lack of choice when selecting synthetic materials with the cell-instructive properties demanded by modern biomaterials. The purpose of this study was to investigate the attachment of cells onto hydrogels prepared from poly(2-oxazoline)s selectively functionalized with cell adhesion motifs. A water-soluble macromer based on the microwave-assisted cationic ring-opening polymerization of 2-methyl-2-oxazoline and 2-(dec-9-enyl)-2-oxazoline was functionalized with the peptide CRGDSG or controls using thiol-ene photochemistry followed by facile cross-linking in the presence of a dithiol cross-linker. The growth of human fibroblasts on the hydrogel surfaces was dictated by the structure and amount of incorporated peptide. Controls without any peptide showed resistance to cellular attachment. The benignity of the cross-linking conditions was demonstrated by the incorporation of fibroblasts within the hydrogels to produce three-dimensional cell-polymer constructs.

  9. Biocompatible hydrogel nanocomposite with covalently embedded silver nanoparticles.

    PubMed

    García-Astrain, Clara; Chen, Cheng; Burón, María; Palomares, Teodoro; Eceiza, Arantxa; Fruk, Ljiljana; Corcuera, M Ángeles; Gabilondo, Nagore

    2015-04-13

    Bionanocomposite materials, combining the properties of biopolymers and nanostructured materials, are attracting interest of the wider scientific community due to their potential application in design of implants, drug delivery systems, and tissue design platforms. Herein, we report on the use of maleimide-coated silver nanoparticles (Ag NPs) as cocross-linkers for the preparation of a bionanocomposite gelatin based hydrogel. Diels-Alder cycloaddition of benzotriazole maleimide (BTM) functionalized Ag NPs and furan containing gelatin in combination with additional amide coupling resulted in stable and biocompatible hybrid nanocomposite. The storage moduli values for the hydrogel are nearly three times higher than that of control hydrogel without NPs indicating a stabilizing role of the covalently bound NPs. Finally, the swelling and drug release properties of the materials as well as the biocompatibility and toxicity tests indicate the biomedical potential of this type of material.

  10. Block copolymer mixtures as antimicrobial hydrogels for biofilm eradication.

    PubMed

    Lee, Ashlynn L Z; Ng, Victor W L; Wang, Weixin; Hedrick, James L; Yang, Yi Yan

    2013-12-01

    Current antimicrobial strategies have mostly been developed to manage infections due to planktonic cells. However, microbes in their nature state will tend to exist by attaching to and growing on living and inanimate surfaces that result in the formation of biofilms. Conventional therapies for treating biofilm-related infections are likely to be insufficient due to the lower susceptibility of microbes that are embedded in the biofilm matrix. In this study, we report the development of biodegradable hydrogels from vitamin E-functionalized polycarbonates for antimicrobial applications. These hydrogels were formed by incorporating positively-charged polycarbonates containing propyl and benzyl side chains with vitamin E moiety into physically cross-linked networks of "ABA"-type polycarbonate and poly(ethylene glycol) triblock copolymers. Investigations of the mechanical properties of the hydrogels showed that the G' values ranged from 1400 to 1600 Pa and the presence of cationic polycarbonate did not affect the stiffness of the hydrogels. Shear-thinning behavior was observed as the hydrogels displayed high viscosity at low shear rates that dramatically decreased as the shear rate increased. In vitro antimicrobial studies revealed that the more hydrophobic VE/BnCl(1:30)-loaded hydrogels generally exhibited better antimicrobial/antifungal effects compared to the VE/PrBr(1:30) counterpart as lower minimum biocidal concentrations (MBC) were observed in Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative) and Candida albicans (fungus) (156.2, 312.5, 312.5 mg/L for VE/BnCl(1:30) and 312.5, 2500 and 625 mg/L for VE/PrBr(1:30) respectively). Similar trends were observed for the treatment of biofilms where VE/BnCl(1:30)-loaded hydrogels displayed better efficiency with regards to eradication of biomass and reduction of microbe viability of the biofilms. Furthermore, a high degree of synergistic antimicrobial effects was also observed through the co

  11. A hydrogel-based enzyme-loaded polymersome reactor

    NASA Astrophysics Data System (ADS)

    de Hoog, Hans-Peter M.; Arends, Isabel W. C. E.; Rowan, Alan E.; Cornelissen, Jeroen J. L. M.; Nolte, Roeland J. M.

    2010-05-01

    In this study we report the immobilization of enzyme-containing polymersomes into a macromolecular hydrogel. Whereas free enzyme shows progressive leakage from the hydrogel in a period of days, leakage of the polymersome-protected enzyme is virtually absent. The preparation of the hydrogel occurs under mild conditions and does not inhibit the activity of the encapsulated enzymes nor does it affect the structure of the polymersomes. The stability of the polymersome hydrogel architecture is demonstrated by the facile recycling of the polymersomes and their use in repeated reaction cycles. A `continuous-flow polymersome reactor' is constructed in which substrate is added to the top of the reactor and product is collected at the bottom. This set-up allows the use of different enzymes and the processing of multiple substrates, as is demonstrated by the conversion of 2-methoxyphenyl acetate to tetraguaiacol in a reactor loaded with polymersome hydrogels containing the enzymes Candida antarctica lipase B (CALB) and glucose oxidase (GOx).

  12. Rapid self-healing hydrogels

    PubMed Central

    Phadke, Ameya; Zhang, Chao; Arman, Bedri; Hsu, Cheng-Chih; Mashelkar, Raghunath A.; Lele, Ashish K.; Tauber, Michael J.; Arya, Gaurav; Varghese, Shyni

    2012-01-01

    Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hydrogel network with flexible-pendant side chains carrying an optimal balance of hydrophilic and hydrophobic moieties that allows the side chains to mediate hydrogen bonds across the hydrogel interfaces with minimal steric hindrance and hydrophobic collapse. The self-healing reported here is rapid, occurring within seconds of the insertion of a crack into the hydrogel or juxtaposition of two separate hydrogel pieces. The healing is reversible and can be switched on and off via changes in pH, allowing external control over the healing process. Moreover, the hydrogels can sustain multiple cycles of healing and separation without compromising their mechanical properties and healing kinetics. Beyond revealing how secondary interactions could be harnessed to introduce new functions to chemically cross-linked polymeric systems, we also demonstrate various potential applications of such easy-to-synthesize, smart, self-healing hydrogels. PMID:22392977

  13. Stretchable Hydrogel Electronics and Devices.

    PubMed

    Lin, Shaoting; Yuk, Hyunwoo; Zhang, Teng; Parada, German Alberto; Koo, Hyunwoo; Yu, Cunjiang; Zhao, Xuanhe

    2016-06-01

    Stretchable hydrogel electronics and devices are designed by integrating stretchable conductors, functional chips, drug-delivery channels, and reservoirs into stretchable, robust, and biocompatible hydrogel matrices. Novel applications include a smart wound dressing capable of sensing the temperatures of various locations on the skin, delivering different drugs to these locations, and subsequently maintaining sustained release of drugs.

  14. Stretchable Hydrogel Electronics and Devices.

    PubMed

    Lin, Shaoting; Yuk, Hyunwoo; Zhang, Teng; Parada, German Alberto; Koo, Hyunwoo; Yu, Cunjiang; Zhao, Xuanhe

    2016-06-01

    Stretchable hydrogel electronics and devices are designed by integrating stretchable conductors, functional chips, drug-delivery channels, and reservoirs into stretchable, robust, and biocompatible hydrogel matrices. Novel applications include a smart wound dressing capable of sensing the temperatures of various locations on the skin, delivering different drugs to these locations, and subsequently maintaining sustained release of drugs. PMID:26639322

  15. Injectable bioadhesive hydrogels with innate antibacterial properties

    NASA Astrophysics Data System (ADS)

    Giano, Michael C.; Ibrahim, Zuhaib; Medina, Scott H.; Sarhane, Karim A.; Christensen, Joani M.; Yamada, Yuji; Brandacher, Gerald; Schneider, Joel P.

    2014-06-01

    Surgical site infections cause significant postoperative morbidity and increased healthcare costs. Bioadhesives used to fill surgical voids and support wound healing are typically devoid of antibacterial activity. Here we report novel syringe-injectable bioadhesive hydrogels with inherent antibacterial properties prepared from mixing polydextran aldehyde and branched polyethylenimine. These adhesives kill both Gram-negative and Gram-positive bacteria, while sparing human erythrocytes. An optimal composition of 2.5 wt% oxidized dextran and 6.9 wt% polyethylenimine sets within seconds forming a mechanically rigid (~\

  16. Facile synthesis of magnetic-/pH-responsive hydrogel beads based on Fe3O4 nanoparticles and chitosan hydrogel as MTX carriers for controlled drug release.

    PubMed

    Wu, Juan; Jiang, Wei; Tian, Renbing; Shen, Yewen; Jiang, Wei

    2016-10-01

    In the present study, methotrexate (MTX)-encapsulated magnetic-/pH-responsive hydrogel beads based on Fe3O4 nanoparticles and chitosan were successfully prepared through a one-step gelation process, which is a very facile, economic and environmentally friendly route. The developed hydrogel beads exhibited homogeneous porous structure and super-paramagnetic responsibility. MTX can be successfully encapsulated into magnetic chitosan hydrogel beads, and the drug encapsulation efficiency (%) and encapsulation content (%) were 93.8 and 6.28%, respectively. In addition, the drug release studies in vitro indicated that the MTX-encapsulated magnetic chitosan hydrogel beads had excellent pH-sensitivity, 90.6% MTX was released from the magnetic chitosan hydrogel beads within 48 h at pH 4.0. WST-1 assays in human liver hepatocellular carcinoma cells (HepG2) demonstrated that the MTX-encapsulated magnetic chitosan hydrogel beads had good cytocompatibility and high anti-tumor activity. Therefore, our results revealed that the MTX-encapsulated magnetic chitosan hydrogel beads would be a competitive candidate for controlled drug release in the area of targeted cancer therapy in the near future.

  17. Facile synthesis of magnetic-/pH-responsive hydrogel beads based on Fe3O4 nanoparticles and chitosan hydrogel as MTX carriers for controlled drug release.

    PubMed

    Wu, Juan; Jiang, Wei; Tian, Renbing; Shen, Yewen; Jiang, Wei

    2016-10-01

    In the present study, methotrexate (MTX)-encapsulated magnetic-/pH-responsive hydrogel beads based on Fe3O4 nanoparticles and chitosan were successfully prepared through a one-step gelation process, which is a very facile, economic and environmentally friendly route. The developed hydrogel beads exhibited homogeneous porous structure and super-paramagnetic responsibility. MTX can be successfully encapsulated into magnetic chitosan hydrogel beads, and the drug encapsulation efficiency (%) and encapsulation content (%) were 93.8 and 6.28%, respectively. In addition, the drug release studies in vitro indicated that the MTX-encapsulated magnetic chitosan hydrogel beads had excellent pH-sensitivity, 90.6% MTX was released from the magnetic chitosan hydrogel beads within 48 h at pH 4.0. WST-1 assays in human liver hepatocellular carcinoma cells (HepG2) demonstrated that the MTX-encapsulated magnetic chitosan hydrogel beads had good cytocompatibility and high anti-tumor activity. Therefore, our results revealed that the MTX-encapsulated magnetic chitosan hydrogel beads would be a competitive candidate for controlled drug release in the area of targeted cancer therapy in the near future. PMID:27464586

  18. Synthesis and characterization of pectin/PVP hydrogel membranes for drug delivery system.

    PubMed

    Mishra, Rakesh K; Datt, Mahesh; Banthia, Ajit K

    2008-01-01

    The purpose of the present study was to develop and design pectin and polyvinyl pyrrolidone (PVP) blended hydrogel membranes (PEVP), with different pectin: PVP ratios (1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1 w/w), which were prepared by using a conventional solution casting technique. An attempt has been made to characterize the hydrogel membranes by various instrumental techniques like, FTIR (Fourier transform infrared) spectroscopy, X-ray diffraction (XRD), Differential scanning calorimetry (DSC), tensile strength test and scanning electron microscopy (SEM). The release patterns of the drug (salicylic acid) from the hydrogel membrane were done in three different release mediums (pH 1.4, pH 7.4 and distilled water) and samples were analyzed spectrophotometrically at 294 nm wavelength on a UV Vis spectrophotometer. MTT assay was done to ensure cytocompatibility of the pectin/PVP hydrogel membranes using B16 melanoma cells. FTIR spectroscopy indicated the presence of secondary amide (I) absorption bands. The XRD study shows decrease in crystallinity of the hydrogel membranes with increase in PVP ratio. DSC study shows an increase in T(g) of pectin after blending with PVP. It was found that tensile strength increases with increasing PVP ratios in the hydrogel membranes. The prepared hydrogel membranes were found to be biocompatible with B16 melanoma cells.

  19. pH and redox sensitive albumin hydrogel: A self-derived biomaterial.

    PubMed

    Raja, S Thirupathi Kumara; Thiruselvi, T; Mandal, Asit Baran; Gnanamani, A

    2015-11-03

    Serum albumin can be transformed to a stimuli (pH and redox) responsive hydrogel using the reduction process followed by oxidative refolding. The preparation of albumin hydrogel involves a range of concentrations (75, 150, 300, 450, 600 and 750 μM) and pH (2.0-10.0) values and the gelation begins at a concentration of 150 μM and 4.5-8.0 pH value. The hydrogel shows maximum swelling at alkali pH (pH > 9.0). The increase in albumin concentration increases hydrogel stability, rheological property, compressive strength, proteolytic resistance and rate of in vivo biodegradation. Based on the observed physical and biological properties of albumin hydrogel, 450 μM was determined to be an optimum concentration for further experiments. In addition, the hemo- and cytocompatibility analyses revealed the biocompatibility nature of albumin hydrogel. The experiments on in vitro drug (Tetracycline) delivery were carried out under non reducing and reducing conditions that resulted in the sustained and fast release of the drug, respectively. The methodology used in the preparation of albumin hydrogel may lead to the development of autogenic tissue constructs. In addition, the methodology can have various applications in tissue engineering and drug delivery.

  20. Radically new cellulose nanocomposite hydrogels: Temperature and pH responsive characters.

    PubMed

    Hebeish, A; Farag, S; Sharaf, S; Shaheen, Th I

    2015-11-01

    Innovation produced for synthesis of radically new stimuli-responsive hydrogels were described. The innovation is based on inclusion of cellulose nanowhiskers (CNW)-polyacrylamide (PAAm) copolymer in poly N-isopropyl acrylamide (PNIPAm) semi interpenetrating network (IPN) hydrogel. After being prepared as per free radical polymerization of AAm onto CNW, the as prepared copolymer was incorporated in a polymerization system, which comprises NIPAm monomer, bismethylene acrylamide (BMA) crosslinker, K2S2O8 initiator and TEMED accelerator, to yield CNW-PAAm-PNIPAm nanocomposite hydrogels. The latter address pH-responsive hydrogel as well as temperature-responsive. Hydrogels exhibit the highest equilibrium swelling ratio (ESR) in acidic medium (pH 4). Meanwhile they perform good swelling behavior and hydrophilicity at a temperature of 32°C. These hydrogels carry the characteristic features of CNW-PAAm copolymer as conducted from FTIR and TGA. The hydrogels are homogenous and well-proportioned network structure with highly connected irregular pores with a large size ranging from 30 to 100nm as concluded from SEM.

  1. Tough and elastic hydrogel of hyaluronic acid and chondroitin sulfate as potential cell scaffold materials.

    PubMed

    Ni, Yilu; Tang, Zhurong; Cao, Wanxu; Lin, Hai; Fan, Yujiang; Guo, Likun; Zhang, Xingdong

    2015-03-01

    Natural polysaccharides are extensively investigated as cell scaffold materials for cellular adhesion, proliferation, and differentiation due to their excellent biocompatibility, biodegradability, and biofunctions. However, their application is often severely limited by their mechanical behavior. In this study, a tough and elastic hydrogel scaffold was prepared with hyaluronic acid (HA) and chondroitin sulfate (CS). HA and CS were conjugated with tyramine (TA) and the degree of substitution (DS) was 10.7% and 11.3%, respectively, as calculated by (1)H NMR spectra. The hydrogel was prepared by mixing HA-TA and CS-TA in presence of H2O2 and HRP. The sectional morphology of hydrogels was observed by SEM, static and dynamic mechanical properties were analyzed by Shimadzu electromechanical testing machine and dynamic mechanical thermal analyzer Q800. All samples showed good ability to recover their appearances after deformation, the storage modulus (E') of hydrogels became higher as the testing frequency went up. Hydrogels also showed fatigue resistance to cyclic compression. Mesenchymal stem cells encapsulated in hydrogels showed good cell viability as detected by CLSM. This study suggests that the hydrogels have both good mechanical properties and biocompatibility, and may serve as model systems to explore mechanisms of deformation and energy dissipation or find some applications in tissue engineering. PMID:25445680

  2. Recent advances in crosslinking chemistry of biomimetic poly(ethylene glycol) hydrogels

    PubMed Central

    Lin, Chien-Chi

    2015-01-01

    The design and application of biomimetic hydrogels have become an important and integral part of modern tissue engineering and regenerative medicine. Many of these hydrogels are prepared from synthetic macromers (e.g., poly(ethylene glycol) or PEG) as they provide high degrees of tunability for matrix crosslinking, degradation, and modification. For a hydrogel to be considered biomimetic, it has to recapitulate key features that are found in the native extracellular matrix, such as the appropriate matrix mechanics and permeability, the ability to sequester and deliver drugs, proteins, and or nucleic acids, as well as the ability to provide receptor-mediated cell-matrix interactions and protease-mediated matrix cleavage. A variety of chemistries have been employed to impart these biomimetic features into hydrogel crosslinking. These chemistries, such as radical-mediated polymerizations, enzyme-mediated crosslinking, bio-orthogonal click reactions, and supramolecular assembly, may be different in their crosslinking mechanisms but are required to be efficient for gel crosslinking and ligand bioconjugation under aqueous reaction conditions. The prepared biomimetic hydrogels should display a diverse array of functionalities and should also be cytocompatible for in vitro cell culture and/or in situ cell encapsulation. The focus of this article is to review recent progress in the crosslinking chemistries of biomimetic hydrogels with a special emphasis on hydrogels crosslinked from poly(ethylene glycol)-based macromers. PMID:26029357

  3. Xylan-based temperature/pH sensitive hydrogels for drug controlled release.

    PubMed

    Gao, Cundian; Ren, Junli; Zhao, Cui; Kong, Weiqing; Dai, Qingqing; Chen, Qifeng; Liu, Chuanfu; Sun, Runcang

    2016-10-20

    Xylan-based temperature/pH sensitive hydrogels were prepared by the crosslinking copolymerization of xylan with N-isopropylacrylamide (NIPAm) and acrylic acid (AA) using N,Ń-methylenebis-acrylamide (MBA) as a cross-linker and 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator via ultraviolet irradiation. The influence of the NIPAm, AA and MBA amount on properties of xylan-based hydrogels was discussed. The morphology and interactions of hydrogels were characterized by SEM and FTIR. The lower critical solution temperature (LCST) of hydrogels was investigated by DSC. The results indicated that the LCST of hydrogels emerged at around 34°C and increased with increasing the AA content. The drug encapsulation efficiency of as-prepared hydrogels reached to 97.60% and the cumulative release rate of acetylsalicylic acid was 90.12% and 26.35% in the intestinal and gastric fluid, respectively. Xylan-based hydrogels were proved to be biocompatible with NIH3T3 cell by MTT assay and showed the promising application as drug carriers for the intestinal-targeted oral drug delivery. PMID:27474557

  4. Synthesis, characterization and applications of N-quaternized chitosan/poly(vinyl alcohol) hydrogels.

    PubMed

    Mohamed, Riham R; Abu Elella, Mahmoud H; Sabaa, Magdy W

    2015-09-01

    Hydrogels composed of N-quaternized chitosan (NQC) and poly(vinyl alcohol) (PVA) in different weight ratios (1:3), (1:1) and (3:1) chemically crosslinked by glutaraldehyde in different weight ratios – 1.0 and 5.0% – have been prepared. The prepared hydrogels were characterized via several analysis tools such as: Fourier transform IR (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). Different applications have been done on NQC/PVA hydrogels including; metal ions uptake, swellability in different buffer solutions (pH: 4, 7 and 9), swellability and degradation studies in simulated body fluid (SBF) solutions and antimicrobial activity towards bacteria and fungi. The results indicated that crosslinked NQC/PVA hydrogels with glutaraldehyde (GA) are more thermallystable than non crosslinked hydrogels, NQC/PVA hydrogels swell highly in different buffer solutions as PVA content increases and the antimicrobial activity of NQC/PVA hydrogels is higher than NQC itself.

  5. pH and redox sensitive albumin hydrogel: A self-derived biomaterial.

    PubMed

    Raja, S Thirupathi Kumara; Thiruselvi, T; Mandal, Asit Baran; Gnanamani, A

    2015-01-01

    Serum albumin can be transformed to a stimuli (pH and redox) responsive hydrogel using the reduction process followed by oxidative refolding. The preparation of albumin hydrogel involves a range of concentrations (75, 150, 300, 450, 600 and 750 μM) and pH (2.0-10.0) values and the gelation begins at a concentration of 150 μM and 4.5-8.0 pH value. The hydrogel shows maximum swelling at alkali pH (pH > 9.0). The increase in albumin concentration increases hydrogel stability, rheological property, compressive strength, proteolytic resistance and rate of in vivo biodegradation. Based on the observed physical and biological properties of albumin hydrogel, 450 μM was determined to be an optimum concentration for further experiments. In addition, the hemo- and cytocompatibility analyses revealed the biocompatibility nature of albumin hydrogel. The experiments on in vitro drug (Tetracycline) delivery were carried out under non reducing and reducing conditions that resulted in the sustained and fast release of the drug, respectively. The methodology used in the preparation of albumin hydrogel may lead to the development of autogenic tissue constructs. In addition, the methodology can have various applications in tissue engineering and drug delivery. PMID:26527296

  6. pH and redox sensitive albumin hydrogel: A self-derived biomaterial

    PubMed Central

    Raja, S Thirupathi Kumara; Thiruselvi, T; Mandal, Asit Baran; Gnanamani, A

    2015-01-01

    Serum albumin can be transformed to a stimuli (pH and redox) responsive hydrogel using the reduction process followed by oxidative refolding. The preparation of albumin hydrogel involves a range of concentrations (75, 150, 300, 450, 600 and 750 μM) and pH (2.0–10.0) values and the gelation begins at a concentration of 150 μM and 4.5–8.0 pH value. The hydrogel shows maximum swelling at alkali pH (pH > 9.0). The increase in albumin concentration increases hydrogel stability, rheological property, compressive strength, proteolytic resistance and rate of in vivo biodegradation. Based on the observed physical and biological properties of albumin hydrogel, 450 μM was determined to be an optimum concentration for further experiments. In addition, the hemo- and cytocompatibility analyses revealed the biocompatibility nature of albumin hydrogel. The experiments on in vitro drug (Tetracycline) delivery were carried out under non reducing and reducing conditions that resulted in the sustained and fast release of the drug, respectively. The methodology used in the preparation of albumin hydrogel may lead to the development of autogenic tissue constructs. In addition, the methodology can have various applications in tissue engineering and drug delivery. PMID:26527296

  7. Smart hydrogel-functionalized textile system with moisture management property for skin application

    NASA Astrophysics Data System (ADS)

    Wang, Xiaowen; Hu, Huawen; Yang, Zongyue; He, Liang; Kong, Yeeyee; Fei, Bin; Xin, John H.

    2014-12-01

    In this study, a functional textile-based material for topical skin application was fabricated by coating a thermoresponsive hydrogel onto one side of absorbent nonwoven fabric. The thermoresponsive hydrogel was synthesized easily through coupling of poly (ethylene glycol) (PEG) and poly (ɛ-caprolactone) (PCL) with hexamethylene diisocyanate (HMDI) as a chemical linker. The chemical structure of the as-prepared triblock copolymer hydrogel was unraveled by FTIR and 1H NMR analysis. The hydrogel showed a temperature-triggered sol-gel transition behavior and high potential for use as drug controlled release. When the surrounding temperature was close to the skin temperature of around 34 °C, it became a moisture management system where the liquids including sweat, blood, and other body fluids can be transported unidirectionally from one fabric side with the hydrophobic hydrogel coating to the untreated opposite side. This thereby showed that the thermoresponsive hydrogel-coated textile materials had a function to keep topical skin area clean, breathable, and comfortable, thus suggesting a great potential and significance for long-term skin treatment application. The structure and surface morphology of the thermoresponsive hydrogel, in vitro drug release behavior, and the mechanism of unidirectional water transport were investigated in detail. Our success in preparation of the functional textile composites will pave the way for development of various polymer- or textile-based functional materials that are applicable in the real world.

  8. Coverage Dependent Charge Reduction of Cationic Gold Clusters on Surfaces Prepared Using Soft Landing of Mass-selected Ions

    SciTech Connect

    Johnson, Grant E.; Priest, Thomas A.; Laskin, Julia

    2012-11-29

    The ionic charge state of monodisperse cationic gold clusters on surfaces may be controlled by selecting the coverage of mass-selected ions soft landed onto a substrate. Polydisperse diphosphine-capped gold clusters were synthesized in solution by reduction of chloro(triphenylphosphine)gold(I) with borane tert-butylamine in the presence of 1,3-bis(diphenylphosphino)propane. The polydisperse gold clusters were introduced into the gas phase by electrospray ionization and mass selection was employed to select a multiply charged cationic cluster species (Au11L53+, m/z = 1409, L = 1,3-bis(diphenylphosphino)propane) which was delivered to the surfaces of four different self-assembled monolayers on gold (SAMs) at coverages of 1011 and 1012 clusters/mm2. Employing the spatial profiling capabilities of in-situ time-of-flight secondary ion mass spectrometry (TOF-SIMS) it is shown that, in addition to the chemical functionality of the monolayer (as demonstrated previously: ACS Nano, 2012, 6, 573) the coverage of cationic gold clusters on the surface may be used to control the distribution of ionic charge states of the soft-landed multiply charged clusters. In the case of a 1H,1H,2H,2H-perfluorodecanethiol SAM (FSAM) almost complete retention of charge by the deposited Au11L53+ clusters was observed at a lower coverage of 1011 clusters/mm2. In contrast, at a higher coverage of 1012 clusters/mm2, pronounced reduction of charge to Au11L52+ and Au11L5+ was observed on the FSAM. When soft landed onto 16- and 11-mercaptohexadecanoic acid surfaces on gold (16,11-COOH-SAMs), the mass-selected Au11L53+ clusters exhibited partial reduction of charge to Au11L52+ at lower coverage and additional reduction of charge to both Au11L52+ and Au11L5+ at higher coverage. The reduction of charge was found to be more pronounced on the surface of the shorter (thinner) C11 than the longer (thicker) C16-COOH-SAM. On the surface of the 1-dodecanethiol (HSAM) monolayer, the most abundant charge state

  9. Design of a shear-thinning recoverable peptide hydrogel from native sequences and application for influenza H1N1 vaccine adjuvant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peptide hydrogels are considered injectable materials for drug delivery and tissue engineering applications. Most published hydrogel-forming sequences contain either alternating-charged and noncharged residues or amphiphilic blocks. Here, we report a self-assembling peptide, h9e (FLIVIGSIIGPGGDGPGGD...

  10. Patterned dual pH-responsive core-shell hydrogels with controllable swelling kinetics and volumes.

    PubMed

    Plunkett, Kyle N; Moore, Jeffrey S

    2004-08-01

    Dual pH-responsive core-shell hydrogels containing both a vinyl pyridine component and a 2-dimethylaminoethyl methacrylate component were prepared using an in situ photopolymerization process. Complementary photomasks were utilized to prepare hydrogels with core/shell volume ratios of 2:1, 1:1, and 1:2. Depending on the location of each polymer component, dramatically different swelling profiles were achieved. Selective swelling of the shell followed by the core components allowed the hydrogel to expand with the usual kinetics; however, by switching the location of each polymer component and swelling the core first, swelling rates decreased by over 1 order of magnitude and were dependent on the shell component's volume. The ability to pattern core/shell volumes also provided the ability to fabricate hydrogels that possess a constant maximum diameter but different cutoff points between its first and its second transition volumes. These materials may be of interest for controlled release applications. PMID:15274549

  11. Photo-crosslinked PDMSstar-PEG Hydrogels: Synthesis, Characterization, and Potential Application for Tissue Engineering Scaffolds

    PubMed Central

    Hou, Yaping; Schoener, Cody A.; Regan, Katherine R.; Munoz-Pinto, Dany; Hahn, Mariah S.; Grunlan, Melissa A.

    2010-01-01

    Inorganic-organic hydrogels with tunable chemical and physical properties were prepared from methacrylated star polydimethylsiloxane (PDMSstar-MA) and diacrylated poly(ethylene glycol) (PEG-DA) for use as tissue engineering scaffolds. Eighteen compositionally unique hydrogels were prepared by photo-crosslinking varying weight ratios of PEG-DA and PDMSstar-MA of different molecular weights (Mn): PEG-DA (Mn = 3.4k and 6k g/mol) and PDMSstar-MA (Mn = 1.8k, 5k and 7k g/mol). Introduction of PDMSstar-MA caused formation of discrete PDMS-enriched microparticles dispersed within the PEG matrix. The swelling ratio, mechanical properties in tension and compression, non-specific protein adhesion, controlled introduction of bioactivity and cytotoxicity of hydrogels were studied. This library of inorganic-organic hydrogels with tunable properties provides a useful platform to study the effect of scaffold properties on cell behavior. PMID:20146518

  12. A zinc/hydrogel system for cathodic protection of reinforced concrete structures

    SciTech Connect

    Bennett, J.; Firlotte, C.

    1996-11-01

    A zinc/hydrogel system has been developed for the cathodic protection of steel in reinforced concrete. This system consists of a thin foil of zinc which is attached to the concrete surface by an ionically conductive hydrogel adhesive. A direct electrical connection between the zinc and the reinforcing steel allows the zinc to function galvanically, polarizing the steel and protecting it from corrosion. Zinc, aluminum, and several aluminum alloys were tested as anodes in contact with hydrogel adhesives, and zinc was found to offer the best combination of working potential, resistance to passivation, cost and availability. Several hydrogels used for medical applications were found to be inadequate for this use, but a hydrogel adhesive was developed specifically to bond sacrificial anodes to concrete. This hydrogel achieved a total charge in accelerated testing equal to 12 years of life at current densities normally used for cathodic protection. Zinc/hydrogel was installed on about 1000 ft{sup 2} (100 m{sup 2}) of a fishing pier in Ft. Pierce, Florida on members including prestressed pilings, conventionally reinforced pile caps, and prestressed beams. Installation of this system was relatively easy, and initial performance is encouraging. After 5 months of service, adhesion is good and current densities remain high.

  13. Hydrogel core flexible matrix composite (H-FMC) actuators: theory and preliminary modelling

    NASA Astrophysics Data System (ADS)

    Dicker, M. P. M.; Weaver, P. M.; Rossiter, J. M.; Bond, I. P.

    2014-09-01

    The underlying theory of a new actuator concept based on hydrogel core flexible matrix composites (H-FMC) is presented. The key principle that underlines the H-FMC actuator operation is that the three-dimensional swelling of a hydrogel is partially constrained in order to improve the amount of useful work done. The partial constraint is applied to the hydrogel by a flexible matrix composite (FMC) that minimizes the hydrogel's volume expansion while swelling. This constraint serves to maximize the fixed charge density and resulting osmotic pressure, the driving force behind actuation. In addition, for certain FMC fibre orientations the Poisson's ratio of the anisotropic FMC laminate converts previously unused hydrogel swelling in the radial and circumferential directions into useful axial strains. The potential benefit of the H-FMC concept to hydrogel actuator performance is shown through comparison of force-stroke curves and evaluation of improvements in useful actuation work. The model used to achieve this couples chemical and electrical components, represented with the Nernst-Plank and Poisson equations, as well as a linear elastic mechanical material model, encompassing limited geometric nonlinearities. It is found that improvements in useful actuation work in the order of 1500% over bare hydrogel performance are achieved by the H-FMC concept. A parametric study is also undertaken to determine the effect of various FMC design parameters on actuator free strain and blocking stress. A comparison to other actuator concepts is also included.

  14. Thiol-norbornene photo-click hydrogels for tissue engineering applications

    PubMed Central

    Lin, Chien-Chi; Ki, Chang Seok; Shih, Han

    2014-01-01

    Thiol-norbornene (thiol-ene) photo-click hydrogels have emerged as a diverse material system for tissue engineering applications. These hydrogels are cross-linked through light mediated orthogonal reactions between multi-functional norbornene-modified macromers (e.g., poly(ethylene glycol), hyaluronic acid, gelatin) and sulfhydryl-containing linkers (e.g., dithiothreitol, PEG-dithiol, bis-cysteine peptides) using low concentration of photoinitiator. The gelation of thiol-norbornene hydrogels can be initiated by long-wave UV light or visible light without additional co-initiator or co-monomer. The cross-linking and degradation behaviors of thiol-norbornene hydrogels are controlled through material selections, whereas the biophysical and biochemical properties of the gels are easily and independently tuned owing to the orthogonal reactivity between norbornene and thiol moieties. Uniquely, the cross-linking of step-growth thiol-norbornene hydrogels is not oxygen-inhibited, therefore the gelation is much faster and highly cytocompatible compared with chain-growth polymerized hydrogels using similar gelation conditions. These hydrogels have been prepared as tunable substrates for 2D cell culture, as microgels or bulk gels for affinity-based or protease-sensitive drug delivery, and as scaffolds for 3D cell culture. Reports from different laboratories have demonstrated the broad utility of thiol-norbornene hydrogels in tissue engineering and regenerative medicine applications, including valvular and vascular tissue engineering, liver and pancreas-related tissue engineering, neural regeneration, musculoskeletal (bone and cartilage) tissue regeneration, stem cell culture and differentiation, as well as cancer cell biology. This article provides an up-to-date overview on thiol-norbornene hydrogel cross-linking and degradation mechanisms, tunable material properties, as well as the use of thiol-norbornene hydrogels in drug delivery and tissue engineering applications. PMID

  15. Elastic hydrogel substrate supports robust expansion of murine myoblasts and enhances their engraftment

    SciTech Connect

    Ding, Ke; Yang, Zhong; Xu, Jian-zhong; Liu, Wen-ying; Zeng, Qiang; Hou, Fang; Lin, Sen

    2015-09-10

    The application of satellite cell-derived myoblasts in regenerative medicine has been restricted by the rapid loss of stemness during in vitro cell expansion using traditional culture systems. However, studies published in the past decade have highlighted the influence of substrate elasticity on stem cell fate and revealed that culture on a soft hydrogel substrate can promote self-renewal and prolong the regenerative potential of muscle stem cells. Whether hydrogel substrates have similar effects after long-term robust expansion remains to be determined. Herein we prepared an elastic chitosan/beta-glycerophosphate/collagen hydrogel mimicking the soft microenvironment of muscle tissues for use as the substrate for satellite cell culture and investigated its influence on long-term cell expansion. After 20 passages in culture, satellite cell-derived myoblasts cultured on our hydrogel substrate exhibited significant improvements in proliferation capability, cell viability, colony forming frequency, and potential for myogenic differentiation compared to those cultured on a routine rigid culture surface. Immunochemical staining and western blot analysis both confirmed that myoblasts cultured on the hydrogel substrate expressed higher levels of several differentiation-related markers, including Pax7, Pax3, and SSEA-1, and a lower level of MyoD compared to myoblasts cultured on rigid culture plates (all p<0.05). After transplantation into the tibialis anterior of nude mice, myoblasts that had been cultured on the hydrogel substrate demonstrated a significantly greater engraftment efficacy than those cultured on the traditional surface. Collectively, these results indicate that the elastic hydrogel substrate supported robust expansion of murine myoblasts and enhanced their engraftment in vivo. - Highlights: • An elastic hydrogel was designed to mimic the pliable muscle tissue microenvironment. • Myoblasts retained their stemness in long-term culture on the elastic

  16. Hyperbranched poly(glycidol)/poly(ethylene oxide) crosslinked hydrogel for tissue engineering scaffold using e-beams.

    PubMed

    Haryanto; Singh, Deepti; Huh, Pil Ho; Kim, Seong Cheol

    2016-01-01

    A microporous hydrogel scaffold was developed from hyperbranched poly(glycidol) (HPG) and poly(ethylene oxide) (PEO) using electron beam (e-beam) induced cross-linking for tissue engineering applications. In this study, HPG was synthesized from glycidol using trimethylol propane as a core initiator and cross-linked hydrogels were made using 0, 10, 20, and 30% HPG with respect to PEO. The effects of %-HPG on the swelling ratio, cross-linking density, mechanical properties, morphology, degradation, and cytotoxicity of the hydrogel scaffolds were then investigated. Increasing the HPG content increased the pore size of the hydrogel scaffold, as well as the porosity, elongation at break, degree of degradation and swelling ratio. In contrast, the presence of HPG decreased the cross-linking density of the hydrogel. There was no significant difference in compressive modulus and tensile strength of all compositions. The pore size of hydrogel scaffolds could be easily tailored by controlling the content of HPG in the polymer blend. Evaluation of the cytotoxicity demonstrated that HPG/PEO hydrogel scaffold has potential for use as a matrix for cellular attachment and proliferation. These results indicate that cross-linked HPG/PEO hydrogel can function as a potential material for tissue engineering scaffolds. Moreover, a facile method to prepare hydrogel microporous scaffolds for tissue engineering by e-beam irradiation was developed.

  17. Extended release of ketotifen from silica shell nanoparticle-laden hydrogel contact lenses: in vitro and in vivo evaluation.

    PubMed

    Maulvi, Furqan A; Mangukiya, Mayurkumar A; Patel, Prachi A; Vaidya, Rutvi J; Koli, Akshay R; Ranch, Ketan M; Shah, Dinesh O

    2016-06-01

    Ketotifen an anti-allergic drug delivered via eye drops has major limitations, including poor ocular bioavailability and poor patient compliance. The objective of the research work was to fabricate ketotifen loaded microemulsion laden hydrogels and silica shell nanoparticle-laden (prepared from microemulsion using octyltrimethoxysilane) hydrogels to achieve extended ocular drug delivery. The porous silica shell membrane was synthesized at the liquid interface of microemulsion, which facilitates the prolongation of drug release duration from hydrogels. Drug encapsulated microemulsion and silica shell nanoparticles were dispersed separately in pre-monomer mixture, and fabricated to hydrogel. For comparison, hydrogel with direct drug entrapment was also fabricated. Significant loss in transmittance and physical properties was observed in hydrogels with direct drug entrapment. While, microemulsion and silica shell nanoparticle-laden hydrogels did not show significant effect on transmittance and physical properties. The in vitro drug release data showed extended release of ketotifen from hydrogels in following order: direct loadinghydrogels. The in vivo pharmacokinetic study showed extended ketotifen release for more than 10 days. The results demonstrated the translational potential of silica shell nanoparticles for extended drug delivery without compromising the critical lens properties. PMID:27178036

  18. Modulated release from liposomes entrapped in chitosan/gelatin hydrogels.

    PubMed

    Ciobanu, Bogdan C; Cadinoiu, Anca N; Popa, Marcel; Desbrières, Jacques; Peptu, Cătălina A

    2014-10-01

    The paper describes the preparation of chitosan/gelatin hydrogels, obtained by double crosslinking with glutaraldehyde and sodium sulphate/sodium tripolyphosphate that may be used as matrices for the inclusion of drug loaded liposomes composed of phosphatidylcholine. The main objective was to create a protective layer to stabilize the liposomal surface and to prolong/control the release of drugs from such systems. Therefore, complex systems capable of prolonged drug release and controlled release kinetics were obtained. Samples consisting of different chitosan/gelatin ratios and type/amount of ionic crosslinker have been prepared and characterized. The present study shows that calcein (used as a model hydrophilic drug) release from polymeric hydrogels has been retarded from several days to weeks after calcein inclusion in small unilamellar vesicles (SUVs) and multilamellar vesicles (MLVs) entrapped subsequently in hydrogels with variable composition. The calcein release kinetics of complex systems were compared to simple systems (control hydrogels) and important changes were observed thus proving that the mechanism of the process increases in complexity. Also, it is demonstrated that liposomes' stability can be greatly improved by inclusion in polymeric matrices. Multilamellar liposomes showed a better release behaviour, which indicates that these calcein loaded vesicles remained intact to some extent after release from the matrix, due to their improved stability provided by the multiple layers. When small unilamellar liposomes were tested, calcein have been released from hydrogels predominantly in a free form (due to their unilamellarity related instability even inside the hydrogel) but in a sustained and controllable manner. The main applications of the systems obtained are in the area of drug release for tissue engineering/tissue repair (topical administration of drugs for wound therapy - burns, for example). Hydrogels capable of delivering drugs over prolonged

  19. Gamma ray-induced synthesis of hyaluronic acid/chondroitin sulfate-based hydrogels for biomedical applications

    NASA Astrophysics Data System (ADS)

    Zhao, Linlin; Gwon, Hui-Jeong; Lim, Youn-Mook; Nho, Young-Chang; Kim, So Yeon

    2015-01-01

    Hyaluronic acid (HA)/chondroitin sulfate (CS)/poly(acrylic acid) (PAAc) hydrogel systems were synthesized by gamma-ray irradiation without the use of additional initiators or crosslinking agents to achieve a biocompatible hydrogel system for skin tissue engineering. HA and CS derivatives with polymerizable residues were synthesized. Then, the hydrogels composed of glycosaminoglycans, HA, CS, and a synthetic ionic polymer, PAAc, were prepared using gamma-ray irradiation through simultaneous free radical copolymerization and crosslinking. The physicochemical properties of the HA/CS/PAAc hydrogels having various compositions were investigated to evaluate their feasibility as artificial skin substitutes. The gel fractions of the HA/CS/PAAc hydrogels increased in absorbed doses up to 15 kGy, and they exhibited 91-93% gel fractions under 15 kGy radiation. All of the HA/CS/PAAc hydrogels exhibited relatively high water contents of over 90% and reached an equilibrium swelling state within 24 h. The enzymatic degradation kinetics of the HA/CS/PAAc hydrogels depended on both the concentration of the hyaluronidase solution and the ratio of HA/CS/PAAc. The in vitro drug release profiles of the HA/CS/PAAc hydrogels were significantly influenced by the interaction between the ionic groups in the hydrogels and the ionic drug molecules as well as the swelling of the hydrogels. From the cytotoxicity results of human keratinocyte (HaCaT) cells cultured with extracts of the HA/CS/PAAc hydrogels, all of the HA/CS/PAAc hydrogel samples tested showed relatively high cell viabilities of more than 82%, and did not induce any significant adverse effects on cell viability.

  20. Syneresis in agar hydrogels.

    PubMed

    Boral, Shilpi; Saxena, Anita; Bohidar, H B

    2010-03-01

    Agar hydrogels exhibit syneresis which creates internal osmotic stress on the physical network. It was observed that such a stress gives rise to characteristic pulsating modes (breathing modes). Experiments carried over a period of 60-day revealed that the network deformations grew monotonously when the solvent released by syneresis was removed periodically from gel surface. However, when the solvent was not withdrawn, the gel exhibited very slowly relaxing breathing modes. The swelling-deswelling dynamics has been discussed in the generalized framework of a dissipative damped oscillator.

  1. Selectively crosslinked hyaluronic acid hydrogels for sustained release formulation of erythropoietin.

    PubMed

    Motokawa, Keiko; Hahn, Sei Kwang; Nakamura, Teruo; Miyamoto, Hajime; Shimoboji, Tsuyoshi

    2006-09-01

    A novel sustained release formulation of erythropoietin (EPO) was developed using hyaluronic acid (HA) hydrogels. For the preparation of HA hydrogels, adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and analyzed with (1)H NMR. The degree of HA-ADH modification was about 69%. EPO was in situ encapsulated into HA-ADH hydrogels through a selective cross-linking reaction of bis(sulfosuccinimidyl) suberate (BS(3)) to hydrazide group (pK(a) = 3.0) of HA-ADH rather than to amine group (pK(a) > 9) of EPO. The denaturation of EPO during HA-ADH hydrogel synthesis was drastically reduced with decreasing pH from 7.4 to 4.8. The specific reactivity of BS(3) to hydrazide at pH = 4.8 might be due to its low pK(a) compared with that of amine. In vitro release of EPO in phosphate buffered saline at 37 degrees C showed that EPO was released rapidly for 2 days and then slowly up to 4 days from HA-ADH hydrogels. When the hydrogels were dried at 37 degrees C for a day, however, longer release of EPO up to 3 weeks could be demonstrated. According to in vivo release test of EPO from HA-ADH hydrogels in SD rats, elevated EPO concentration higher than 0.1 ng/mL could be maintained from 7 days up to 18 days depending on the preparation methods of HA-ADH hydrogels. There was no adverse effect during and after HA-ADH hydrogel implantation. PMID:16721757

  2. Spermidine-cross-linked hydrogels as novel potential platforms for pharmaceutical applications.

    PubMed

    López-Cebral, Rita; Paolicelli, Patrizia; Romero-Caamaño, Vanessa; Seijo, Begoña; Casadei, Maria Antonietta; Sanchez, Alejandro

    2013-08-01

    Endogen polyamines are known to be molecules of high biological value. Herein, a new generation of physical hydrogels was developed through the mild ionotropic gelantion technique, using the endogen polyamine spermidine as a physical cross-linker. The main negatively charged polymer of the hydrogel is the natural polysaccharide gellan gum. Optionally, interesting endogen molecules, such as chondroitin sulfate and albumin, can be included as part of the formulation. These new hydrogels were characterized and the influence of the different components on their final properties was carefully analyzed, ultimately demonstrating the possibility to modulate these properties as well as the system's versatility in terms of composition. On the contrary, in vitro cell studies showed the absence of cytotoxicity of these hydrogels. Finally, the in vitro-release profiles obtained for different model molecules evidenced the potential of these systems as novel drug delivery platforms. PMID:23757346

  3. Supramolecular Packing Controls H₂ Photocatalysis in Chromophore Amphiphile Hydrogels.

    PubMed

    Weingarten, Adam S; Kazantsev, Roman V; Palmer, Liam C; Fairfield, Daniel J; Koltonow, Andrew R; Stupp, Samuel I

    2015-12-01

    Light harvesting supramolecular assemblies are potentially useful structures as components of solar-to-fuel conversion materials. The development of these functional constructs requires an understanding of optimal packing modes for chromophores. We investigated here assembly in water and the photocatalytic function of perylene monoimide chromophore amphiphiles with different alkyl linker lengths separating their hydrophobic core and the hydrophilic carboxylate headgroup. We found that these chromophore amphiphiles (CAs) self-assemble into charged nanostructures of increasing aspect ratio as the linker length is increased. The addition of salt to screen the charged nanostructures induced the formation of hydrogels and led to internal crystallization within some of the nanostructures. For linker lengths up to seven methylenes, the CAs were found to pack into 2D crystalline unit cells within ribbon-shaped nanostructures, whereas the nine methylene CAs assembled into long nanofibers without crystalline molecular packing. At the same time, the different molecular packing arrangements after charge screening led to different absorbance spectra, despite the identical electronic properties of all PMI amphiphiles. While the crystalline CAs formed electronically coupled H-aggregates, only CAs with intermediate linker lengths showed evidence of high intermolecular orbital overlap. Photocatalytic hydrogen production using a nickel-based catalyst was observed in all hydrogels, with the highest turnovers observed for CA gels having intermediate linker lengths. We conclude that the improved photocatalytic performance of the hydrogels formed by supramolecular assemblies of the intermediate linker CA molecules likely arises from improved exciton splitting efficiencies due to their higher orbital overlap. PMID:26593389

  4. Soft nanotube hydrogels functioning as artificial chaperones.

    PubMed

    Kameta, Naohiro; Masuda, Mitsutoshi; Shimizu, Toshimi

    2012-06-26

    Self-assembly of rationally designed asymmetric amphiphilic monomers in water produced nanotube hydrogels in the presence of chemically denatured proteins (green fluorescent protein, carbonic anhydrase, and citrate synthase) at room temperature, which were able to encapsulate the proteins in the one-dimensional channel of the nanotube consisting of a monolayer membrane. Decreasing the concentrations of the denaturants induced refolding of part of the encapsulated proteins in the nanotube channel. Changing the pH dramatically reduced electrostatic attraction between the inner surface mainly covered with amino groups of the nanotube channel and the encapsulated proteins. As a result, the refolded proteins were smoothly released into the bulk solution without specific additive agents. This recovery procedure also transformed the encapsulated proteins from an intermediately refolding state to a completely refolded state. Thus, the nanotube hydrogels assisted the refolding of the denatured proteins and acted as artificial chaperones. Introduction of hydrophobic sites such as a benzyloxycarbony group and a tert-butoxycarbonyl group onto the inner surface of the nanotube channels remarkably enhanced the encapsulation and refolding efficiencies based on the hydrophobic interactions between the groups and the surface-exposed hydrophobic amino acid residues of the intermediates in the refolding process. Refolding was strongly dependent on the inner diameters of the nanotube channels. Supramolecular nanotechnology allowed us to not only precisely control the diameters of the nanotube channels but also functionalize their surfaces, enabling us to fine-tune the biocompatibility. Hence, these nanotube hydrogel systems should be widely applicable to various target proteins of different molecular weights, charges, and conformations.

  5. Sundew adhesive: a naturally occurring hydrogel

    PubMed Central

    Huang, Yujian; Wang, Yongzhong; Sun, Leming; Agrawal, Richa; Zhang, Mingjun

    2015-01-01

    Bioadhesives have drawn increasing interest in recent years, owing to their eco-friendly, biocompatible and biodegradable nature. As a typical bioadhesive, sticky exudate observed on the stalked glands of sundew plants aids in the capture of insects and this viscoelastic adhesive has triggered extensive interests in revealing the implied adhesion mechanisms. Despite the significant progress that has been made, the structural traits of the sundew adhesive, especially the morphological characteristics in nanoscale, which may give rise to the viscous and elastic properties of this mucilage, remain unclear. Here, we show that the sundew adhesive is a naturally occurring hydrogel, consisting of nano-network architectures assembled with polysaccharides. The assembly process of the polysaccharides in this hydrogel is proposed to be driven by electrostatic interactions mediated with divalent cations. Negatively charged nanoparticles, with an average diameter of 231.9 ± 14.8 nm, are also obtained from this hydrogel and these nanoparticles are presumed to exert vital roles in the assembly of the nano-networks. Further characterization via atomic force microscopy indicates that the stretching deformation of the sundew adhesive is associated with the flexibility of its fibrous architectures. It is also observed that the adhesion strength of the sundew adhesive is susceptible to low temperatures. Both elasticity and adhesion strength of the sundew adhesive reduce in response to lowering the ambient temperature. The feasibility of applying sundew adhesive for tissue engineering is subsequently explored in this study. Results show that the fibrous scaffolds obtained from sundew adhesive are capable of increasing the adhesion of multiple types of cells, including fibroblast cells and smooth muscle cells, a property that results from the enhanced adsorption of serum proteins. In addition, in light of the weak cytotoxic activity exhibited by these scaffolds towards a variety of

  6. Effect of cross-linking reagents for hyaluronic acid hydrogel dermal fillers on tissue augmentation and regeneration.

    PubMed

    Yeom, Junseok; Bhang, Suk Ho; Kim, Byung-Soo; Seo, Moo Seok; Hwang, Eui Jin; Cho, Il Hwan; Park, Jung Kyu; Hahn, Sei Kwang

    2010-02-17

    A novel, biocompatible, and nontoxic dermal filler using hyaluronic acid (HA) hydrogels was successfully developed for tissue augmentation applications. Instead of using highly reactive cross-linkers such as divinyl sulfone (DVS) for Hylaform, 1,4-butanediol diglycidyl ether (BDDE) for Restylane, and 1,2,7,8-diepoxyoctane (DEO) for Puragen, HA hydrogels were prepared by direct amide bond formation between the carboxyl groups of HA and hexamethylenediamine (HMDA) with an optimized carboxyl group modification for effective tissue augmentation. The HA-HMDA hydrogels could be prepared within 5 min by the addition of HMDA to HA solution activated with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) and 1-hydroxybenzotriazole monohydrate (HOBt). Five kinds of samples, a normal control, a negative control, a positive control of Restylane, adipic acid dihydrazide grafted HA (HA-ADH) hydrogels, and HA-HMDA hydrogels, were subcutaneously injected to wrinkled model mice. According to the image analysis on dorsal skin augmentation, the HA-HMDA hydrogels exhibited the best t