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Sample records for acid copolymeric hydrogels

  1. Swelling and thermodynamic studies of temperature responsive 2-hydroxyethyl methacrylate/itaconic acid copolymeric hydrogels prepared via gamma radiation

    International Nuclear Information System (INIS)

    Tomic, Simonida L.J.; Micic, Maja M.; Filipovic, Jovanka M.; Suljovrujic, Edin H.

    2007-01-01

    The copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) were synthesized by gamma radiation induced radical polymerization. Swelling and thermodynamic properties of PHEMA and copolymeric P(HEMA/IA) hydrogels with different IA contents (2, 3.5 and 5 mol%) were studied in a wide pH and temperature range. Initial studies of so-prepared hydrogels show interesting pH and temperature sensitivity in swelling and drug release behavior. Special attention was devoted to temperature investigations around physiological temperature (37 deg. C), where small changes in temperature significantly influence swelling and drug release of these hydrogels. Due to maximum swelling of hydrogels around 40 deg. C, the P(HEMA/IA) hydrogel containing 5 mol% of IA without and with drug-antibiotic (gentamicin) were investigated at pH 7.40 and in the temperature range 25-42 deg. C, in order to evaluate their potential for medical applications

  2. Swelling and drug release behavior of poly(2-hydroxyethyl methacrylate/itaconic acid) copolymeric hydrogels obtained by gamma irradiation

    International Nuclear Information System (INIS)

    Tomic, S.Lj.; Micic, M.M.; Filipovic, J.M.; Suljovrujic, E.H.

    2007-01-01

    The new copolymeric hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) were prepared by gamma irradiation, in order to examine the potential use of these hydrogels in controlled drug release systems. The influence of IA content in the gel on the swelling characteristics and the releasing behavior of hydrogels, and the effect of different drugs, theophylline (TPH) and fenethylline hydrochloride (FE), on the releasing behavior of P(HEMA/IA) matrix were investigated in vitro. The diffusion exponents for swelling and drug release indicate that the mechanisms of buffer uptake and drug release are governed by Fickian diffusion. The swelling kinetics and, therefore, the release rate depends on the matrix swelling degree. The drug release was faster for copolymeric hydrogels with a higher content of itaconic acid. Furthermore, the drug release for TPH as model drug was faster due to a smaller molecular size and a weaker interaction of the TPH molecules with(in) the P(HEMA/IA) copolymeric networks

  3. Thermosensitive copolymeric hydrogels with the regulated temperature of a phase transition

    International Nuclear Information System (INIS)

    Samchenko, Yu.M.; Konovalova, V.V.; Korotich, E.I.; Poltoratskaya, T.P.; Pobegaj, A.A.; Burban, A.F.; Ul'berg, Z.R.; Samchenko, Yu.M.; Konovalova, V.V.; Korotich, E.I.; Poltoratskaya, T.P.; Pobegaj, A.A.; Burban, A.F.; Ul'berg, Z.R.

    2011-01-01

    The work is devoted to the methods of obtaining the thermosensitive copolymeric hydrogels based on the NIPAAm with acrylic acid and its derivatives such as acrylamide, acrylonitrile, and methylacrylate. The mechanisms of thermoinitiated phase transitions in hydrogel matrices and the regularities of the thermoinitiated release of model compounds and drugs (aniline, novocaine, and sodium diclofenac) from copolymeric hydrogel are investigated.

  4. Radiation-induced synthesis and swelling properties of p(2-hydroxyethyl methacrylate-co-itaconic acid-co-oligo(ethylene glycol) acrylate) copolymeric hydrogels

    International Nuclear Information System (INIS)

    Micic, M.; Suljovrujic, E.

    2011-01-01

    Complete text of publication follows. Since it is presumed that by incorporation of pH-responsive (IA) and temperature-responsive (OEGA) co-monomers it is possible to prepare P(HEMA-co-IA-co-OEGA) hydrogels with duel (pH and thermo) responsiveness, the main purpose of this paper is to investigate the influence of different mole fractions of IA and especially OEGA on the diversity of the swelling properties of obtained hydrogels. For that reason, a series of copolymeric hydrogels with different mole ratios of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and oligo(ethylene glycol) acrylates (OEGA) was synthesized by gamma radiation. The obtained hydrogels were characterized by swelling studies in the wide pH (2.2-9.0) and temperature range (25-70 deg C), confirming dual (pH and thermo) responsiveness and a large variation in swelling capability. It was observed that the equilibrium swelling of P(HEMA-co-IA-co-OEGA) hydrogels, for a constant amount of IA, increases progressively with increasing in OEGA share. On the other hand, the dissociation of carboxyl (-COOH) groups from IA occurs at pH > 4; therefore, small mole fractions of IA render good pH sensitivity and a large increase in the swelling capacity of these hydrogels at higher pH values. Additional characterization of structure and properties was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and mechanical measurements, confirming that the inherent properties of the P(HEMA-co-IA-co-OEGA) hydrogels can be significantly tuned by variation in their composition. According to all presented, it seems that the obtained copolymeric hydrogels can be a beneficial synergetic combination for controlled delivery of bioactive molecules such as drugs, nucleic acids, peptides, and proteins.

  5. Structural and behavioral characteristics of radiolytically synthesized polyacrylic acid–polyacrylonitrile copolymeric hydrogels

    International Nuclear Information System (INIS)

    Bera, Anuradha; Misra, R.K.; Singh, Shailendra K.

    2013-01-01

    Copolymeric hydrogels of polyacrylic acid (PAA) – polyacrylonitrile (PAN) was radiolytically synthesized from their respective monomers with trimethyloltrimethacrylate (TMPTMA) as the crosslinker wherein both polymerization and crosslinking could be achieved in a single step reaction using 60 Co γ-radiation under varying doses and dose rates. The formation of the hydrogels was confirmed by their FT-IR analysis, while their thermal degradation patterns were investigated through thermogravimetric analysis in both the dry and swelled state. The water sorption studies showed rapid swelling behavior of these hydrogels, where swelling (%EWC) was found to be strongly dependent on the ratio of the two monomers in the hydrogels and the swelling kinetics dependent on the dose rates of hydrogel synthesis. These radiolytically synthesized hydrogels responded to electrical stimulus both in terms of the bending speed as well as bending angle under an applied voltage. The nature of the deformation was reversible and can be controlled through switching the voltage on and off. - Highlights: • Polyacrylic acid – polyacrilonitrile copolymeric hydrogel has been radiolytically synthesized. • Trimethyloltrimethacrylate (TMPTMA) used as crosslinker. • Hydrogel has been characterized and tested for electroresponsive character. • Bending angles and bending speed were found dependent upon applied voltage

  6. Inverse opal pH sensors with various protic monomers copolymerized with polyhydroxyethylmethacrylate hydrogel

    International Nuclear Information System (INIS)

    Shin, Jinsub; Han, Sung Gu; Lee, Wonmok

    2012-01-01

    Highlights: ► We polymerized four different inverse opal pH sensors by using vinyl monomers containing acidic or basic substituents. ► Stepwise swelling response from polyprotic acid sensor was investigated. ► Opposite color changing responses were obtained for acidic and basic sensors. ► Composite pH sensor with wide pH sensing range was fabricated by mixing different monomers. ► Both acid and base sensors show the response time as fast as ∼10 s. - Abstract: pH sensitive inverse opal sensors were synthesized using various vinyl monomers containing acidic or basic substituents. Acrylic acid (AA), vinylphosphonic acid (VPA), vinylimidazole (VI), and dimethylaminoethylmethacrylic acid (DMAEMA) were respectively copolymerized with hydroxyethylmethacrylate (HEMA), the building block monomer of the hydrogel via UV-initiated photopolymerization. Opal templating and subsequent template removal enabled the fabrication of four inverse opal (IO) hydrogel colorimetric sensors, which responded to pH in different fashions. pH-dependent swelling of the IO hydrogel induced the red-shift of the diffracted color. The sensors containing AA or VPA, the proton donating monomers showed the color shifts from green to red with pH increase due to the increased concentration of carboxylate anions bound to the hydrogel. Diprotic VPA sensor exhibited two-step increases of diffracted wavelengths at its pK a1 and pK a2 respectively. The sensors containing proton acceptors, VI and DMAEMA showed the pH-dependent color changes in an opposite way to the AA sensor and the VPA sensor since their ionizations take place by lowering pH due to the protonation at the amino groups. The shapes of pH response curves of VI and DMAEMA sensors were similar but pK b s were different from each other. Optical diffraction responses of four sensors were compared with the calculated concentration ratios of the ionized species to the total monomer with pH variation, and a deswelling effect in the

  7. Cyto- and genotoxicological assessment and functional characterization of N-vinyl-2-pyrrolidone-acrylic acid-based copolymeric hydrogels with potential for future use in wound healing applications

    International Nuclear Information System (INIS)

    Kirf, Dominik; Devery, Sinead M; Higginbotham, Clement L; Rowan, Neil J

    2010-01-01

    This study investigated the toxicity of N-vinyl-2-pyrrolidone-acrylic acid copolymer hydrogels crosslinked with ethylene glycol dimethacrylate or poly(ethylene glycol) dimethacrylate. There is a pressing need to establish the toxicity status of these new copolymers because they may find applications in future wound healing processes. Investigations revealed that the capacity of these hydrogels for swelling permitted the retention of high amounts of water yet still maintaining structural integrity. Reverse phase HPLC analysis suggested that unreacted monomeric base material was efficiently removed post-polymerization by applying an additional purification process. Subsequently, in vitro toxicity testing was performed utilizing direct and indirect contact exposure of the polymers to human keratinocytes (HaCaT) and human hepatoma (HepG2) cells. No indication of significant cell death was observed using the established MTT, neutral red (NR) and fluorescence-based toxicity endpoint indicators. In addition, the alkaline Comet assay showed no genotoxic effects following cell exposure to hydrogel extracts. Investigations at the nucleotide level using the Ames mutagenicity assay demonstrated no evidence of mutagenic activity associated with the polymers. Findings from this study demonstrated that these hydrogels are non-cytotoxic and further work can be carried out to investigate their potential as a wound-healing device that will impact positively on patient health and well-being.

  8. Cyto- and genotoxicological assessment and functional characterization of N-vinyl-2-pyrrolidone-acrylic acid-based copolymeric hydrogels with potential for future use in wound healing applications

    Energy Technology Data Exchange (ETDEWEB)

    Kirf, Dominik; Devery, Sinead M [Department of Life and Physical Science, Athlone Institute of Technology (Ireland); Higginbotham, Clement L [Materials Research Institute, Athlone Institute of Technology (Ireland); Rowan, Neil J, E-mail: sdevery@ait.i, E-mail: dkirf@ait.i, E-mail: chigginbotham@ait.i, E-mail: nrowan@ait.i [Department of Nursing and Health Science, Athlone Institute of Technology (Ireland)

    2010-06-01

    This study investigated the toxicity of N-vinyl-2-pyrrolidone-acrylic acid copolymer hydrogels crosslinked with ethylene glycol dimethacrylate or poly(ethylene glycol) dimethacrylate. There is a pressing need to establish the toxicity status of these new copolymers because they may find applications in future wound healing processes. Investigations revealed that the capacity of these hydrogels for swelling permitted the retention of high amounts of water yet still maintaining structural integrity. Reverse phase HPLC analysis suggested that unreacted monomeric base material was efficiently removed post-polymerization by applying an additional purification process. Subsequently, in vitro toxicity testing was performed utilizing direct and indirect contact exposure of the polymers to human keratinocytes (HaCaT) and human hepatoma (HepG2) cells. No indication of significant cell death was observed using the established MTT, neutral red (NR) and fluorescence-based toxicity endpoint indicators. In addition, the alkaline Comet assay showed no genotoxic effects following cell exposure to hydrogel extracts. Investigations at the nucleotide level using the Ames mutagenicity assay demonstrated no evidence of mutagenic activity associated with the polymers. Findings from this study demonstrated that these hydrogels are non-cytotoxic and further work can be carried out to investigate their potential as a wound-healing device that will impact positively on patient health and well-being.

  9. Rheological Behavior of Reaction Mixtures during the Graft Copolymerization of Cassava Starch with Acrylic Acid

    NARCIS (Netherlands)

    Witono, J.R.; Noordergraaf, Inge; Heeres, Hero; Janssen, L.P.B.M.

    2017-01-01

    Literature data on the rheological behavior of a reaction mixture during the graft copolymerization of acrylic acid onto gelatinized starch are scarce. Yet, such information is important for process design. In this work, continuous torque recording was found to be a suitable method to monitor the

  10. Enzymatically crosslinked silk-hyaluronic acid hydrogels.

    Science.gov (United States)

    Raia, Nicole R; Partlow, Benjamin P; McGill, Meghan; Kimmerling, Erica Palma; Ghezzi, Chiara E; Kaplan, David L

    2017-07-01

    In this study, silk fibroin and hyaluronic acid (HA) were enzymatically crosslinked to form biocompatible composite hydrogels with tunable mechanical properties similar to that of native tissues. The formation of di-tyrosine crosslinks between silk fibroin proteins via horseradish peroxidase has resulted in a highly elastic hydrogel but exhibits time-dependent stiffening related to silk self-assembly and crystallization. Utilizing the same method of crosslinking, tyramine-substituted HA forms hydrophilic and bioactive hydrogels that tend to have limited mechanics and degrade rapidly. To address the limitations of these singular component scaffolds, HA was covalently crosslinked with silk, forming a composite hydrogel that exhibited both mechanical integrity and hydrophilicity. The composite hydrogels were assessed using unconfined compression and infrared spectroscopy to reveal of the physical properties over time in relation to polymer concentration. In addition, the hydrogels were characterized by enzymatic degradation and for cytotoxicity. Results showed that increasing HA concentration, decreased gelation time, increased degradation rate, and reduced changes that were observed over time in mechanics, water retention, and crystallization. These hydrogel composites provide a biologically relevant system with controllable temporal stiffening and elasticity, thus offering enhanced tunable scaffolds for short or long term applications in tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Radiation-initiated emulsion copolymerization of styrene and carboxylic acid monomers

    International Nuclear Information System (INIS)

    Egusa, S.; Makuuchi, K.

    1982-01-01

    The emulsion copolymerization of styrene and carboxylic acid monomers such as acrylic, methacrylic, and itaconic acids (AAc, MAAc, IAc) was studied by using 60 Co γ-rays as initiator and sodium dodecylsulfate as emulsifier. The polymerization behavior of these acid monomers was followed by simultaneous conductometric and potentiometric titrations for a latex sample taken in polymerization. The polymerization rate of these acid monomers increases in the following order of hydrophobicity: IAc < AAc < MAAc; this suggests that their polymerization sites are mainly the surface and/or subsurface regions of latex particles. The copolymerization rate of styrene and acid monomer increases with an increase in the acid monomer content for AAc and MAAc, whereas for IAc the rate decreases. The particle sizes determined by the stopped-flow method reveal that this variation of copolymerization rate cannot be explained by the number of growing particles and should be attributed to another factor; for instance, the transfer rate of styrene molecules from oil droplets to growing particles

  12. Electronically Stabilized Copoly(Styrene-Acrylic Acid Submicrocapsules Prepared by Miniemulsion Copolymerization

    Directory of Open Access Journals (Sweden)

    Minkwan Kim

    2017-07-01

    Full Text Available This work reports the preparation and characterization of poly(styrene-acrylic acid (St/AA submicrocapsules by using the miniemulsion copolymerization method. AA was introduced to miniemulsion polymerization of St to increase the zeta potential and the resulting electrostatic stability of St/AA submicrocapsules. Phytoncide oil was adopted as the core model material. Miniemulsion copolymerization of St and AA was conducted at a fixed monomer concentration (0.172 mol with a varying monomer feed ratio [AA]/[St] (0.2, 0.25, 0.33, 0.5, and 1.0. Concentrations of initiator (azobisisobutyronitrile; 1.0 × 10−3, 2.0 × 10−3, 3.0 × 10−3, and 4.0 × 10−3 mol/mol of monomer and surfactant (sodium dodecyl sulfate; 0.6 × 10−3, 1.0 × 10−3, and 1.4 × 10−3 mol were also controlled to optimize the miniemulsion copolymerization of St and AA. Dynamic light scattering and microscopic analyses confirmed the optimum condition of miniemulsion copolymerization of St and AA. Long-term colloidal stability of aqueous St/AA submicrocapsule suspension was evaluated by using TurbiscanTM Lab. In this work, the optimum condition for miniemulsion copolymerization of St and AA was determined ([AA]/[St] = 0.33; [SDS] = 1.0 × 10−3 mol; [AIBN] = 2.0 × 10−3 mol/mol of monomer. St/AA submicrocapsules prepared at the optimum condition (392.6 nm and −55.2 mV of mean particle size and zeta potential, respectively showed almost no variations in backscattering intensity (stable colloids without aggregation.

  13. Gamma ray-induced synthesis of hyaluronic acid/chondroitin sulfate-based hydrogels for biomedical applications

    Science.gov (United States)

    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.

  14. Design of a single-step immunoassay principle based on the combination of an enzyme-labeled antibody release coating and a hydrogel copolymerized with a fluorescent enzyme substrate in a microfluidic capillary device.

    Science.gov (United States)

    Wakayama, Hideki; Henares, Terence G; Jigawa, Kaede; Funano, Shun-ichi; Sueyoshi, Kenji; Endo, Tatsuro; Hisamoto, Hideaki

    2013-11-21

    A combination of an enzyme-labeled antibody release coating and a novel fluorescent enzyme substrate-copolymerized hydrogel in a microchannel for a single-step, no-wash microfluidic immunoassay is demonstrated. This hydrogel discriminates the free enzyme-conjugated antibody from an antigen-enzyme-conjugated antibody immunocomplex based on the difference in molecular size. A selective and sensitive immunoassay, with 10-1000 ng mL(-1) linear range, is reported.

  15. Biocompatible and bioadhesive hydrogels based on 2-hydroxyethyl methacrylate, monofunctional poly(alkylene glycols and itaconic acid

    Directory of Open Access Journals (Sweden)

    Mićić Maja M.

    2007-01-01

    Full Text Available New types of hydrogels were prepared by the radical copolymerization of 2-hydroxyethyl methacrylate, itaconic acid and four different poly(alkylene glycol (methacrylate components (Bisomers in a water/ethanol mixture as solvent. The polymers swell in water at 25°C to yield homogeneous transparent hydrogels. All the hydrogels displayed pH sensitive behavior in buffers of the pH range from 2.20 to 7.40, under conditions similar to those of biological fluids. The presence of these two comonomers, which were added to HEMA, increased the swelling degree of the hydrogels and gave gels with better elasticity. The hydrogels were thermally stable in the vicinity of the physiological temperature (37°C. The copolymer containing pure poly(ethylene glycol acrylate units generally had the best properties. The tests performed on the hydrogels confirmed that they were neither hemolytic nor cytotoxic. The copolymer samples showed better cell viability and less hemolytic activity than the PHEMA sample, confirming the assumption that poly(alkylene glycols improve the biocompatibility of hydrogels. Due to their swelling and mechanical characteristics, as well as the very good biocompatibility and bioadhesive properties, poly(Bisomer/HEMA/IA hydrogels are promising for utilization in the field of biomedicals, especially for the controlled release of drugs.

  16. Y-shaped Folic Acid-Conjugated PEG-PCL Copolymeric Micelles for Delivery of Curcumin.

    Science.gov (United States)

    Feng, Runliang; Zhu, Wenxia; Chu, Wei; Teng, Fangfang; Meng, Ning; Deng, Peizong; Song, Zhimei

    2017-01-01

    Curcumin is a natural hydrophobic product showing anticancer activity. Many studies show its potential use in the field of cancer treatment due to its safety and efficiency. However, its application is limited due to its low water-solubility and poor selective delivery to cancer. A Y-shaped folic acid-modified poly (ethylene glycol)-b-poly (ε-caprolactone)2 copolymer was prepared to improve curcumin solubility and realize its selective delivery to cancer. The copolymer was synthesized through selective acylation reaction of folic acid with α- monoamino poly(ethylene glycol)-b-poly(ε-caprolactone)2. Curcumin was encapsulated into the copolymeric micelles with 93.71% of encapsulation efficiency and 11.94 % of loading capacity. The results from confocal microscopy and cellular uptake tests showed that folic acid-modified copolymeric micelles could improve cellular uptake of curcumin in Hela and HepG2 cells compared with folic acid-unmodified micelles. In vitro cytotoxicity assay showed that folic acid-modified micelles improved anticancer activity against Hela and HepG2 cells in comparison to folic acidunmodified micelles. Meanwhile, both drug-loaded micelles demonstrated higher activity against Hela cell lines than HepG2. The research results suggested that the folic acid-modified Y-shaped copolymeric micelles should be used to enhance hydrophobic anticancer drugs' solubility and their specific delivery to folic acid receptors-overexpressed cancer. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  17. Gamma ray-induced synthesis of hyaluronic acid/chondroitin sulfate-based hydrogels for biomedical applications

    International Nuclear Information System (INIS)

    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. - Highlights: • HA/CS/PAAc hydrogels were synthesized by gamma-ray irradiation. • HA/CS/PAAc hydrogels exhibited 91–93% gel fractions under 15 kGy radiation. • All of the HA/CS/PAAc hydrogels exhibited high water contents of over 90%. • The hydrogel samples showed relatively high cell viabilities of more than

  18. In vitro release studies of vitamin B12 from poly N-vinyl pyrrolidone /starch hydrogels grafted with acrylic acid synthesized by gamma radiation

    International Nuclear Information System (INIS)

    Eid, M.

    2008-01-01

    Co-polymeric hydrogels containing N-vinyl pyrrolidone and starch grafted with acrylic acid were synthesized by gamma radiation. Their gel contents, grafting process and swelling were evaluated. The gels were also characterized by thermal gravimetric analysis. The gel content found to be increase with increasing the irradiation dose up to 50 kGy then decrease. The grafting percent increase by increasing the percentage of acrylic acid in the grafted hydrogels. The thermal stability and the rate of the thermal decomposition showed to be changed according to the different composition of the hydrogels. It also showed a decrease in the maximum rate of the thermal decomposition by the increasing of the irradiation dose from 20 to 30 kGy and increases by increasing the irradiation dose from 30 to 70 kGy. The hydrogels loaded with vitamin B 12 as drug model, demonstrated a decrease release in acidic medium than the neutral one

  19. Antioxidant activity and controlled drug delivery potential of tragacanth gum-cl- poly (lactic acid-co-itaconic acid) hydrogel.

    Science.gov (United States)

    Gupta, Vinod Kumar; Sood, Swadeep; Agarwal, Shilpi; Saini, Adesh K; Pathania, Deepak

    2018-02-01

    Tragacanth gum-cl-poly (lactic acid-co-itaconic acid) (TG-cl-p(LA-co-IA)) hydrogel is synthesized through graft copolymerization reaction using microwave assisted technique. The synthesized hydrogel was characterised using various analytical and characterization techniques such as FTIR, FESEM, XRD, TGA, TEM and SEM. It was observed that, the maximum percentage swelling (P s ) of the hydrogel was 311.61% after 6h at room temperature and 298.06% after 3h at 60°C and TG-cl-p(LA-co-IA) exhibited highest Amoxicillin loading (73%) in double distilled waterafter 24h. From the controlled release studies, it was evident that maximum drug release of about 96% took place at pH 2.2=after 6h. The synthesized hydrogel also showed mild antioxidant properties and 43.85% of free radical scavenging was occurred at a concentration of 640μg/mL and hence it can be effectively used to reduce the oxidative stresses. In addition to this, the antibacterial studies also showed that it is more effective against S. aureus. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Radiation synthesis and characterization of polyacrylic acid hydrogels

    International Nuclear Information System (INIS)

    Yang Mingcheng; Song Hongyan; Zhu Chengshen; He Suqin

    2007-01-01

    The pH-sensitive polyacrylic acid (PAA) hydrogels were synthesized by gamma-ray irradiation at an ambient temperature. The influences of dose, monomer concentration, cross-linking agent content, pH, and ionic strength on the swelling ratio (SR) of the PAA hydrogels were investigated in detail. The results show that the SR of the hydrogel decreases with an increase in the dose, monomer concentration, and cross-linking agent content. In alkaline solution, the SR of the hydrogels is much higher than that in acid solution. Also, the ionic strength can influence the SR of the hydrogels. The more the concentration, the lower the SR. (authors)

  1. Radiation Synthesis and Characterization of Polyvinyl alcohol/Acrylic acid Hydrogel and its Amoxicillin drug Delivery application

    International Nuclear Information System (INIS)

    El kelesh, N.A.; Ismail, S.A.; Abd El Wahab, S.Y.

    2012-01-01

    Polyvinyl alcohol /Acrylic acid based hydrogels can be synthesized by Gamma radiation technique using 60 Co irradiation cell at irradiation dose rate 1.8 Gray/second. The optimum conditions of hydrogel preparation takes place at different factors such as composition ratios of PVA/AAc, different comonomer concentration and different irradiation doses resulting in hydrogel with maximum gel percent as it obtained 98%. The structures of hydrogels were characterized by FTIR analysis. The results can be confirmed the expected structures as well as free radical copolymerization. According to the swelling studies, hydrogels with high content of AAc gave relatively high swelling percent. The hydrogel showed a super adsorbent with swelling capacity 10320 %. Water diffusion into such prepared hydrogel showed a non-Fickian type where a Fickian number was 0.77. This hydrogel was used for the adsorption of amoxicillin drug from their aqueous solutions. The factors affected on the uptake conditions such as ph, time and initial feed concentration on the amoxicillin adsorption capacity of hydrogel was studied depending on Freundlish model of adsorption isotherm.. It was observed that the interaction between drug and ionic comonomers was enhanced in alkaline medium and high initial feed concentration of the drug. The ability of the hydrogel and the affinity of the drug to be adsorbed can be cleared by determining the empirical constants n and k respectively from the logarithmic form of Freundlish equation. The recovery of drug was also investigated in different ph values to study the suitable condition of drug release as drug delivery system.

  2. Molecular design of light-responsive hydrogels, for in situ generation of fast and reversible valves for microfluidic applications

    NARCIS (Netherlands)

    Schiphorst, ter J.; Coleman, S.; Stumpel, J.E.; Ben Azouz, A.; Diamond, D.; Schenning, A.P.H.J.

    2015-01-01

    Reversible light-responsive hydrogel valves with response characteristics compatible for microfluidics have been obtained by optimization of molecular design of spiropyran photoswitches and gel composition. Self-protonating gel formulations were exploited, wherein acrylic acid was copolymerized in

  3. Radiation-induced graft copolymerization of methyl acrylate and acrylic acid onto rubber wood fiber

    International Nuclear Information System (INIS)

    Saliza Jam; Mansor Ahmad; Wan Md Zin Wan Yunus; Khairul Zaman Mohd Dahlan

    2001-01-01

    Graft copolymerization of methyl acrylate and acrylic acid monomers onto rubber wood fiber (RWF) was carried out by simultaneous radiation-induced technique. The parameters affecting the grafting reaction were investigated and the optimum conditions for both monomers obtained are as follows: impregnation time = 16 hours, total dose = 30 kGy, methanol : water ratio, 3:1, monomers concentration = 40 v/v % and sulphuric acid concentration = 0.1 mol/L. Fourier Transform Infrared (FTIR), thermogravimetry analysis (TGA), and scanning electron microscope (SEM) analyses used to characterize graft copolymers. The structural investigation by x-ray diffraction (XRD) shows the degree of crystallinity of rubber wood fiber decreased with the incorporation of poly(methyl acrylate) and poly(acrylic acid) grafts. (Author)

  4. Radiation-induced copolymerizations of perfluorovinyl acetic acid and its methyl ester with α-olefin

    International Nuclear Information System (INIS)

    Kawaguchi, M.; Watanabe, T.; Matsuda, O.; Tabata, Y.; Machi, S.

    1981-01-01

    Homopolymerizations and copolymerizations of perfluorovinyl acetic acid (FVA) and its methyl ester (MFVA) were carried out by γ radiation at a temperature of 25 0 C, a dose rate of 1 x 10 6 rad/hr, and FVA/α-olefin and MFVA/α-olefin ratios of 10/90-90/10 in the monomer mixture. FVA and MFVA gave small quantities of brown and greasy low-molecular-weight homopolymers. The polymerization rates of both FVA and MFVA were extremely small, as shown by the maximum G value of monomer consumption of 12. FVA and MFVA reacted with α-olefin to form waxlike copolymers. The copolymerization rates of both FVA and MFVA with α-olefin were remarkably larger than those of the homopolymerizations, particularly with ethylene. The polymer compositions of FVA/ethylene or MFVA/ethylene were nearly 1/2 over a wide range of the monomer compositions. The Mayo-Lewis method gave negative r 1 (FVA) and r 1 (MFVA). The polymer composition curves could be well interpreted by introducing the penultimate model

  5. Optimal Design for Reactivity Ratio Estimation: A Comparison of Techniques for AMPS/Acrylamide and AMPS/Acrylic Acid Copolymerizations

    Directory of Open Access Journals (Sweden)

    Alison J. Scott

    2015-11-01

    Full Text Available Water-soluble polymers of acrylamide (AAm and acrylic acid (AAc have significant potential in enhanced oil recovery, as well as in other specialty applications. To improve the shear strength of the polymer, a third comonomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS, can be added to the pre-polymerization mixture. Copolymerization kinetics of AAm/AAc are well studied, but little is known about the other comonomer pairs (AMPS/AAm and AMPS/AAc. Hence, reactivity ratios for AMPS/AAm and AMPS/AAc copolymerization must be established first. A key aspect in the estimation of reliable reactivity ratios is design of experiments, which minimizes the number of experiments and provides increased information content (resulting in more precise parameter estimates. However, design of experiments is hardly ever used during copolymerization parameter estimation schemes. In the current work, copolymerization experiments for both AMPS/AAm and AMPS/AAc are designed using two optimal techniques (Tidwell-Mortimer and the error-in-variables-model (EVM. From these optimally designed experiments, accurate reactivity ratio estimates are determined for AMPS/AAm (rAMPS = 0.18, rAAm = 0.85 and AMPS/AAc (rAMPS = 0.19, rAAc = 0.86.

  6. Glucose-Sensitive Hydrogel Optical Fibers Functionalized with Phenylboronic Acid.

    Science.gov (United States)

    Yetisen, Ali K; Jiang, Nan; Fallahi, Afsoon; Montelongo, Yunuen; Ruiz-Esparza, Guillermo U; Tamayol, Ali; Zhang, Yu Shrike; Mahmood, Iram; Yang, Su-A; Kim, Ki Su; Butt, Haider; Khademhosseini, Ali; Yun, Seok-Hyun

    2017-04-01

    Hydrogel optical fibers are utilized for continuous glucose sensing in real time. The hydrogel fibers consist of poly(acrylamide-co-poly(ethylene glycol) diacrylate) cores functionalized with phenylboronic acid. The complexation of the phenylboronic acid and cis-diol groups of glucose enables reversible changes of the hydrogel fiber diameter. The analyses of light propagation loss allow for quantitative glucose measurements within the physiological range. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Graft copolymerization of N-maleoyl-N-phthaloyl-chitosan (MAPHCS) and acrylic acid via γ-ray irradiation

    International Nuclear Information System (INIS)

    Mu Qing; Fang Yue'e

    2006-01-01

    Chitosan is a well-known abundant natural polymer with good biodegradability, biocompatibility and bioactivity. But its insolubility in common organic solvents of chitosan have hindered its utilization and basic research. N-maleoyl-N-phthaloyl-chitosan (MAPHCS), soluble in DMF or DMSO, was synthesized and characterized by Fourier transform infrared spectra analysis (FT-IR) and 1 H-NMR. The graft copolymerization of acrylic acid onto chitosan was carried out with N-maleoyl-N-phthaloyl-chitosan as intermediate in homogeneous system and initiated by γ-irradiation. The double bond of MAPHCS may be the grafting site because the grafting field was much higher than that of the graft copolymerization of acrylic acid and phthaloylchitosan via γ-ray irradiation. The chemical structure of the graft copolymer was characterized by FT-IR and 1 H-NMR. As indicated in FTIR spectra, the evidence of the stronger absorbance at 2800-3000 cm -1 for C-H and at 1720 cm -1 for carboxyl group implied significantly the successful introduction of the poly (acrylic acid) on the chitosan chain. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were also used to characterize the copolymer. Effects of synthesis variables on the graft copolymerization were studied in light of the grafting percentage. The grafting percentage increased with the dose at lower doses, and then decreased. The maximum grafting percentage was up to 132%. (authors)

  8. Flexible Polymeric Materials Prepared by Radiation Copolymerization of MMA/ Pyridene in the Presence of Acrylic Acid

    International Nuclear Information System (INIS)

    Hegazy, D.E.

    2014-01-01

    Gamma-irradiation initiated copolymerization of methyl methacrylate (MMA) and pyridine (Py) was carried out at room temperature.To improve the obtained copolymer functionality and molecular weight, acrylic acid (AA) was incorporated into the mixture during irradiation. The samples were characterized by thermal analysis techniques (DSC and TGA), Fourier transform infrared spectroscopy (FTIR) and UV-VIS spectrometry. Molecular weight of the obtained copolymers was determined using gel permeation chromatography (GPC). The variation of refractive index and surface hardness with the molecular weight were also investigated. The results obtained show a decrease in glass transition temperature and the hardness (shore D) of the supporting matrix for P(MMA/Py) copolymers with a pronounced increase of the molecular weight. The addition of PAA into the matrix enhanced the hardness and shifts the glass transition temperature to a little higher temperature with a pronounced decrease in the melting temperature. The obtained materials maintain good structural order and flexibility resulting from the softening effect of pyridine onto MMA matrix. The studies performed made possible the selection of experimental conditions to be adequate for the production of new co polymeric materials with high molecular weight that having good flexibility and transparent properties.

  9. A novel dextran hydrogel linking trans-ferulic acid for the stabilization and transdermal delivery of vitamin E.

    Science.gov (United States)

    Cassano, Roberta; Trombino, Sonia; Muzzalupo, Rita; Tavano, Lorena; Picci, Nevio

    2009-05-01

    Long-term exposure of the skin to UV light causes degenerative effects, which can be minimized by using antioxidant formulations. The major challenge in this regard is that a significant amount of antioxidant should reach at the site for effective photoprotection. However, barrier properties of the skin limit their use. In the present study, vitamin E (alpha-tocopherol) was loaded into a dextran hydrogel containing ferulic moieties, covalently linked, to improve its topical delivery, and also to increase its relative poor stability, which is due to direct exposure to UV light. Methacrylic groups were first introduced onto the dextran polymer backbones, then the obtained methacrylated dextran was copolymerized with aminoethyl methacrylate, and subsequently esterificated with trans-ferulic acid. The new biopolymer was characterized by Fourier transform infrared spectroscopy. The values of content of phenolic groups were determined. Its ability in inhibiting lipid peroxidation in rat liver microsomal membranes induced in vitro by a source of free radicals, that is tert-butyl hydroperoxide, was studied. Hydrogel was also characterized for swelling behaviour, vitamin E loading efficiency, release, and deposition on the rabbit skin. Additionally, vitamin E deposition was compared through hydrogels, respectively, containing and not containing trans-ferulic acid. The results showed that ferulate hydrogel was a more effective carrier in protecting vitamin E from photodegradation than hydrogel without antioxidant moieties. Then antioxidant hydrogel could be of potential use for cosmetic and pharmaceutical purposes as carrier of vitamin E that is an antioxidant that reduces erythema, photoaging, photocarcinogenesis, edema, and skin hypersensitivity associated with exposure to ultraviolet B (UVB) radiation, because of its protective effects.

  10. Radiation graft copolymerization of styrene with m/e and styrene with acrylic acid at highthyl methacryl dose rate

    International Nuclear Information System (INIS)

    Aliev, R.Eh.; Kabanov, B.Ya.

    1984-01-01

    Comparative investigation of radiation graft copolymerization of styrene with methyl methacrylate (MMA) and styrene with acrylic acid (AA) is carried out at considerably differing radiation dose rates. The monomer mixture was grafted to PE low density films at dose rates of 0.16, 0.25 Gy/s (1 MeV electron acceleration). The value of graft was 3-6 and 5-10%, respectively, for the styrene-MMA and styrene-AA systems. An essential difference in the dependences of the formed copolymer composition on initial monomer mixture composition is noticed. Difference in composition of graft polymers prepared at different dose rates is less for the systems with AA, than for systems with MMA. It is shown that at high dose rates in difference with low ones not only radical graft copolymerization of the styrene mixture with AA takes place, but a contribution of the graft styrene polymerization according to cation mechanism as well

  11. Ultrasound stimulated release of gallic acid from chitin hydrogel matrix

    International Nuclear Information System (INIS)

    Jiang, Huixin; Kobayashi, Takaomi

    2017-01-01

    Ultrasound (US) stimulated drug release was examined in this study using a chitin hydrogel matrix loaded with gallic acid (GA), a drug used for wound healing and anticancer. Using phase inversion, GA-chitin hydrogels were prepared from chitin-dimethylacetamide (DMAc)/lithium chloride (LiCl) solution in the presence of GA, with 24 h exposure of the solution to water vapor. The GA release from the GA-chitin hydrogel was examined under different US powers of 0–30 W at 43 kHz. The effects of GA loading amounts in the hydrogels (0.54, 0.43, and 0.25 mg/cm 3 ) and chitin concentrations (0.1, 0.5, and 1 wt%) on the release behaviors were recorded under 43 kHz US exposure at 30 W. Results show that US accelerated the release efficiencies for all samples. Furthermore, the release efficiency increased concomitantly with increasing US power, GA loading amount, and decrease of the chitin concentration. The highest release rate of 0.74 μg/mL·min was obtained from 0.54 mg/cm 3 of GA-loaded hydrogel fabricated from a 0.1 wt% chitin mixture solution under 43 kHz US exposure at 30 W: nine times higher than that of the sample without US exposure. The hydrogel viscoelasticity demonstrated that the US irradiation rigidified the material. FT-IR showed that US can break the hydrogen bonds in the GA-chitin hydrogels. - Highlights: • Ultrasound (US) stimulated Gallic acid (GA) release from chitin hydrogel was studied. • The release efficiency of GA from chitin hydrogel increased nine times when irradiated by 43 kHz US compared with the sample without US. • Generalized 2D correlation and deconvolution study of FT-IR showed that US could promote the GA release by breaking hydrogen bonds.

  12. Ultrasound stimulated release of gallic acid from chitin hydrogel matrix

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Huixin; Kobayashi, Takaomi, E-mail: takaomi@nagaokaut.ac.jp

    2017-06-01

    Ultrasound (US) stimulated drug release was examined in this study using a chitin hydrogel matrix loaded with gallic acid (GA), a drug used for wound healing and anticancer. Using phase inversion, GA-chitin hydrogels were prepared from chitin-dimethylacetamide (DMAc)/lithium chloride (LiCl) solution in the presence of GA, with 24 h exposure of the solution to water vapor. The GA release from the GA-chitin hydrogel was examined under different US powers of 0–30 W at 43 kHz. The effects of GA loading amounts in the hydrogels (0.54, 0.43, and 0.25 mg/cm{sup 3}) and chitin concentrations (0.1, 0.5, and 1 wt%) on the release behaviors were recorded under 43 kHz US exposure at 30 W. Results show that US accelerated the release efficiencies for all samples. Furthermore, the release efficiency increased concomitantly with increasing US power, GA loading amount, and decrease of the chitin concentration. The highest release rate of 0.74 μg/mL·min was obtained from 0.54 mg/cm{sup 3} of GA-loaded hydrogel fabricated from a 0.1 wt% chitin mixture solution under 43 kHz US exposure at 30 W: nine times higher than that of the sample without US exposure. The hydrogel viscoelasticity demonstrated that the US irradiation rigidified the material. FT-IR showed that US can break the hydrogen bonds in the GA-chitin hydrogels. - Highlights: • Ultrasound (US) stimulated Gallic acid (GA) release from chitin hydrogel was studied. • The release efficiency of GA from chitin hydrogel increased nine times when irradiated by 43 kHz US compared with the sample without US. • Generalized 2D correlation and deconvolution study of FT-IR showed that US could promote the GA release by breaking hydrogen bonds.

  13. Synthesis and Characterization of pH and Thermo Dual-Responsive Hydrogels with a Semi-IPN Structure Based on N-Isopropylacrylamide and Itaconamic Acid.

    Science.gov (United States)

    Rwei, Syang-Peng; Tuan, Huynh Nguyen Anh; Chiang, Whe-Yi; Way, Tun-Fun

    2018-04-28

    A series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated in this study. Linear copolymer poly( N -isopropylacrylamide-co-itaconamic acid) p(NIPAM-co-IAM), which is formed by copolymerization of N -isopropylacrylamide (NIPAM) and itaconamic acid (IAM, 4-amino-2-ethylene-4-oxobutanoic acid), was introduced into a solution of NIPAM to form a series of pH and thermo dual-responsive p(NIPAM-co-IAM)/pNIPAM semi-IPN hydrogels by free radical polymerization. The structural, morphological, chemical, and physical properties of the linear copolymer and semi-IPN hydrogels were investigated. The semi-IPN hydrogel showed high thermal stability according to thermal gravimetric analyzer (TGA). Scanning electronic microscopy (SEM) images showed that the pore size was in the range of 119~297 µm and could be controlled by the addition ratio of the linear copolymer in the semi-IPN structure. The addition of linear copolymer increased the fracture strain from 57.5 ± 2.9% to 91.1 ± 4.9% depending on the added amount, while the compressive modulus decreased as the addition increased. Moreover, the pH and thermo dual-responsive properties were investigated using differential scanning calorimetry (DSC) and monitoring the swelling behavior of the hydrogels. In deionized (DI) water, the equilibrium swelling ratio of the hydrogels decreased as the temperature increased from 20 °C to 50 °C, while it varied in various pH buffer solutions. In addition, the swelling and deswelling rates of the hydrogels also significantly increased. The results indicate that the novel pH-thermo dual-responsive semi-IPN hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery, or absorption application.

  14. Water absorbency of chitosan grafted acrylic acid hydrogels

    Science.gov (United States)

    Astrini, N.; Anah, L.; Haryono, A.

    2017-07-01

    Acrylic acid (AA) monomer was directly grafted onto chitosan (CTS) using potassium persulfate (KPS) as an initiator and methylenebisacrylamide (MBA) as a crosslinking agent under an inert atmosphere. One factor affecting the swelling capacity of the obtained hydrogel, KPS concentration, were studied. The hydrogel products were characterized using Fourier Transform Infrared spectroscopy (FTIR) for chemical structure and scanning electron microscopy (SEM) for morphology. Swelling of the hydrogel samples in distilled water and saline solution ( 9% NaCl ) was examined. Swelling capacity of the CTS-g-PAA hydrogels in distilled water (88.53 g/g) was higher than in NaCl solution (29.94 g/g) The highest swelling capacity value was obtained when the grafted reaction was carried out using 2.5wt% initiator

  15. Biomimetic hydrogel materials

    Science.gov (United States)

    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.

  16. Determination of Monomers Reactivity Ratios in Ethyl Acrylate-Methacrylic Acid Copolymerization by Off-Line 1H NMR

    Directory of Open Access Journals (Sweden)

    Samaneh Ashenagar

    2017-03-01

    Full Text Available The physical, chemical and mechanical properties of polymer systems depend on the micro-structural characteristics of their macromolecular chains. Along with the most characteristic kinetic parameters in copolymerization reactions are the reactivity ratios, which give a clear idea of the average composition and the monomer sequence distribution in copolymer systems. This research studies the solution radical copolymerization of methacrylic acid (MAA-ethyl acrylate (EA system at low conversion with 2,2'-azobisisobutyronitrile (AIBN as thermal initiator at 60°C in deuterated dimethyl sulfoxide (DMSO-d6 as a reaction solvent. In this case, the monomer reactivity ratios were determined using linear off-line 1H nuclear magnetic resonance spectroscopy (1H NMR methods such as Mayo-Louis, Finemann-Ross, Inverted Finemann-Ross , Ezrielev-Brokhina-Roskin, Joshi-Joshi, Kelen-Tudos, extended Kelen- Tudos, Mao-Huglin at low and high conversions. The next estimation process in off-line 1H NMR methods were performed by applying techniques based on ordinary least square (OLS and generalized least square (GLS. The results showed that the GLS approach compared to the OLS increased regression coefficients (R2 and the order of magnitude of parameter variances obtained from GLS was many times lower than that obtained from OLS. In addition, the monomer reactivity ratios obtained by the Mao-Huglin method and the GLS approach showed the best linear estimation.

  17. Injectable hydrogels derived from phosphorylated alginic acid calcium complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han-Sem; Song, Minsoo, E-mail: minsoosong00@gmail.com; Lee, Eun-Jung; Shin, Ueon Sang, E-mail: usshin12@dankook.ac.kr

    2015-06-01

    Phosphorylation of sodium alginate salt (NaAlg) was carried out using H{sub 3}PO{sub 4}/P{sub 2}O{sub 5}/Et{sub 3}PO{sub 4} followed by acid–base reaction with Ca(OAc){sub 2} to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for {sup 1}H, and {sup 31}P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2 w/v%) with NaAlg solution (2 w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO{sub 4} or CaCl{sub 2} were added externally. The gelation was completed within about 3–40 min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤ 6.7 kPa for compressive strength at break and about 8.4 kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100–800 μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering. - Highlights: • Preparation of water-soluble alginic acid complexes with calcium phosphate • Self-assembly of the phosphorylated alginic acid calcium complexes with sodium alginate • Preparation of injectable hydrogels with diverse gelation times within about 3–40 min.

  18. Graft copolymerization of acrylic acid to cassava starch-Evaluation of the influences of process parameters by an experimental design method

    NARCIS (Netherlands)

    Witono, J. R.; Noordergraaf, I. W.; Heeres, H. J.; Janssen, L. P. B. M.

    2012-01-01

    The graft copolymerization of cassava starch with acrylic acid was investigated using a free radical initiator system (Fe2+/H2O2 redox system) in water. A comprehensive understanding of the important variables and their interaction has been obtained by applying an experimental design method. In this

  19. Effect of acid additives on graft copolymerization and water absorption of graft copolymers of cassava starch and acrylamide/acrylic acid

    International Nuclear Information System (INIS)

    Kiatkamjornwong, Suda; Mongkolsawat, Kanlaya; Sonsuk, Manit

    2003-01-01

    Gelatinized cassava starch was radiation graft copolymerized with acrylamide or acrylic acid in the presence of sulfuric acid, nitric acid or maleic acid at a specific dose rate to a fixed total dose. Homopolymer or free copolymer was extracted by water to obtain the pure graft copolymer, which was subsequently saponified with 5% potassium hydroxide solution at room temperature for 90 min. The saponified graft copolymer was investigated for the effect of acid additives and water absorption. The addition of 2% maleic acid into the grafting reaction containing acrylamide-to-starch ratio of 2.5:1 can produce the superabsorbent copolymer having water absorption as high as 2,256 ± 25 g g -1 . The effect of acid additive was explained. (author)

  20. Manual of radiation processing of cassava starch hydrogel

    International Nuclear Information System (INIS)

    Sonsuk, Manit

    2007-01-01

    The radiation processing of natural cassava starch (CS) is described for the improvement of its properties. A series of hydrogels were prepared from gelatinized CS and vinylpyrrolidone by radiation-induced graft copolymerization. Hydrogels were also synthesized from radiation-induced crosslinking of carboxymethyl CS. The optimum condition for the swelling ratio and gel fraction of the obtained hydrogels is irradiation at low dose. The polymeric chelating resins containing the hydroxamic acid groups were synthesized from the polymethyl acrylate (PMA)-grafted CS via gamma radiation. (M.H.)

  1. ph Sensitive hydrogel as colon specific drug delivery

    International Nuclear Information System (INIS)

    Alarifi, A.S.

    2011-01-01

    γ-radiation induced graft copolymerization and crosslinking was for the synthesis of ph-sensitive hydrogels composed of poly (vinyl pyrrolidone) acrylic acid. The prepared hydrogels were subjected to swelling test to evaluate the effects of ph and ionic strength of the surrounding solution. Drastic changes in the swelling parameters where observed by changing the surrounding solution ph values. The release of ibuprofen from hydrogels was monitored as a function of time at ph 1 and ph 7 in order to evaluate the prepared copolymer ability for colon- specific drug carrier uses.

  2. Synthesis and Properties of IPN Hydrogels Based on Konjac Glucomannan and Poly(acrylic acid)

    Institute of Scientific and Technical Information of China (English)

    Bing LIU; Zhi Lan LIU; Ren Xi ZHUO

    2006-01-01

    Novel interpenetrating polymer network (IPN) hydrogels based on konjac glucomannan (KGM) and poly(acrylic acid) (PAA) were prepared by polymerization and cross-linking of acrylic acid (AA) in the pre-fabricated KGM gel. The IPN gel was analyzed by FT-IR. The studies on the equilibrium swelling ratio of IPN hydrogels revealed their sensitive response to environmental pH value. The results of in vitro degradation showed that the IPN hydrogels retain the enzymatic degradation character of KGM.

  3. Extraction of americium (III) by thermosensitive polymer gel copolymerized with acidic phosphorus compound

    International Nuclear Information System (INIS)

    Takeshita, Kenji; Nakano, Yoshio; Matsumura, Tatsuro

    2001-01-01

    A new gel-liquid extraction using a thermosensitive gel was proposed. The thermosensitive gel shows the conformational change of polymer network with temperature, which is known as the phase transition phenomena of gel. The extraction rate and equilibrium of Am(III) in an aqueous solution containing nitrate ion were measured batchwise by using a thermosensitive gel, N-isopropylacrylamide (NIPA) copolymerized with 2-methacryloyloxy- ethylacidphosphate (MR). The effects of the conformational change of polymer network on the extraction rate and equilibrium were discussed. The distribution ratio of Am(III) showed a large value at higher than LCST (low critical solution temperature; 34degC) and was decreased by the phase transition of gel from shrinking to swelling with decreasing temperature. The extraction of Am(III) in the aqueous solution and the release of Am(III) extracted in the gel were repeated stably by the temperature swing operation between 40 and 3degC. The extraction mechanism of Am(III) was described simply as Am 3+ + 3R - OH=(R-O) 3 Am + 3H + (R-OH: MR). The equilibrium constant at the shrinking state (40degC) was more than 3 times of that at swelling state (3degC). The gel-phase diffusivity of Eu(III) used as a substitute of Am(III) was evaluated as the order of 10 -12 m 2 /s at either of 3 or 40degC, which was similar to those for practical extraction chromatographic resins. The temperature-response of gel for the extraction of Eu(III) was very excellent without delay even for the rapid temperature change at 10degC/min. These results suggest that the extraction and release of Am(III) in an aqueous solution can be controlled by the conformational change of polymer network of thermosensitive gel. (author)

  4. Preparation and Study on Properties of Superabsorbent Hydrogel Composites of Acrylamide-Acrylic Acid and Zeolite in Agricultural Uses

    Directory of Open Access Journals (Sweden)

    Shohreh Vosuoghi

    2017-11-01

    Full Text Available Water shortage is one of the most important environmental problems in arid and semi-arid areas which cause complications in land vegetations. The use of superabsorbent hydrogel is one of the most vital methods, which helps to optimize agricultural irrigations. The purpose of this research is preparation and study on properties the superabsorbent hydrogels by copolymerization of acrylamide and acrylic acid monomers using zeolite as nanoclay particles (0, 0.05, 0.1, 0.15. The optimum amount of nanoparticles in relation to its effect on superabsorbent structure and properties, such as water absorbency, was investigated through designing experiments using FFD software. We used methylene bisacrylamide and ammonium ‌persulfate as crosslinker and initiator, respectively. Thermogravimetric analysis (TGA, Fourier transform spectroscopy (FTIR, scanning electron microscopy (SEM and X-ray diffractometry (XRD test results showed that the addition of nanoclay up to 0.1g caused improvement in the physical and chemical properties of superabsorbent such as thermal resistance, porous structure and uniform network structure. The superabsorbent hydrogel could absorb 1100 (g/g distilled water. The water absorption and water retention of superabsorbent were studied by loading it in 5 different soil texture classes which were 0:100, 25:75, 50:50, 75:25 and 100:0 mixture fractions of sand/loam soil. As a result, it was observed that in the first week after irrigation, the best retention of initial moisture belonged to the soil with 50% sand texture, and also the soil with sand texture returned to its initial weight after 53 days (i.e., 30 days later than the control sample.

  5. Supermacroporous chemically cross-linked poly(aspartic acid) hydrogels.

    Science.gov (United States)

    Gyarmati, Benjámin; Mészár, E Zsuzsanna; Kiss, Lóránd; Deli, Mária A; László, Krisztina; Szilágyi, András

    2015-08-01

    Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by a solid-liquid phase separation technique, cryogelation, to achieve a supermacroporous interconnected pore structure. The precursor polymer of PASP, polysuccinimide (PSI) was cross-linked below the freezing point of the solvent and the forming crystals acted as templates for the pores. Dimethyl sulfoxide was chosen as solvent instead of the more commonly used water. Thus larger temperatures could be utilized for the preparation and the drawback of increase in specific volume of water upon freezing could be eliminated. The morphology of the hydrogels was characterized by scanning electron microscopy and interconnectivity of the pores was proven by the small flow resistance of the gels. Compression tests also confirmed the interconnected porous structure and the complete re-swelling and shape recovery of the supermacroporous PASP hydrogels. The prepared hydrogels are of interest for several biomedical applications as scaffolding materials because of their cytocompatibility, controllable morphology and pH-responsive character. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Surface-modified silk hydrogel containing hydroxyapatite nanoparticle with hyaluronic acid-dopamine conjugate.

    Science.gov (United States)

    Kim, Hyung Hwan; Park, Jong Bo; Kang, Min Ji; Park, Young Hwan

    2014-09-01

    Silk fibroin/hydroxyapatite (SF/HAp) composite hydrogels were fabricated in this study, having different HAp contents (0-33 wt%) in SF matrix hydrogel. Surface modification of HAp nanoparticle with hyaluronic acid (HA)-dopamine (DA) conjugate improved a dispersibility of HAp in aqueous SF solution due to its negatively charged surface and therefore, fabrication of the SF composite hydrogel having HAp nanoparticles inside could be possible. Zeta potential of surface-modified HAP was examined by ELS. It demonstrates that surface of HAp was well modified to a negative charge with HA-DA. Morphological structure of SF hydrogel containing surface-modified HAp was examined by FE-SEM for analyzing pore structure of hydrogel and deposition of HAp nanoparticle in SF hydrogel. It was found that HAp nanoparticles were uniformly deposited on the pore wall of SF hydrogel. Structural characteristics of SF/HAp composite hydrogel was performed using X-ray diffraction and FT-IR analysis. It was found that β-sheet crystal conformation of SF was significantly influenced by the HAp content during gelation of a mixture of SF and HAp. As a result of MTT assay, the SF/HAp composite hydrogel showed excellent cell proliferation ability. Therefore, it is expected that SF hydrogel containing HAp nanoparticles has a high potential as bone regeneration scaffold. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

  8. Biodegradation and Osteosarcoma Cell Cultivation on Poly(aspartic acid) Based Hydrogels.

    Science.gov (United States)

    Juriga, Dávid; Nagy, Krisztina; Jedlovszky-Hajdú, Angéla; Perczel-Kovách, Katalin; Chen, Yong Mei; Varga, Gábor; Zrínyi, Miklós

    2016-09-14

    Development of novel biodegradable and biocompatible scaffold materials with optimal characteristics is important for both preclinical and clinical applications. The aim of the present study was to analyze the biodegradability of poly(aspartic acid)-based hydrogels, and to test their usability as scaffolds for MG-63 osteoblast-like cells. Poly(aspartic acid) was fabricated from poly(succinimide) and hydrogels were prepared using natural amines as cross-linkers (diaminobutane and cystamine). Disulfide bridges were cleaved to thiol groups and the polymer backbone was further modified with RGD sequence. Biodegradability of the hydrogels was evaluated by experiments on the base of enzymes and cell culture medium. Poly(aspartic acid) hydrogels possessing only disulfide bridges as cross-links proved to be degradable by collagenase I. The MG-63 cells showed healthy, fibroblast-like morphology on the double cross-linked and RGD modified hydrogels. Thiolated poly(aspartic acid) based hydrogels provide ideal conditions for adhesion, survival, proliferation, and migration of osteoblast-like cells. The highest viability was found on the thiolated PASP gels while the RGD motif had influence on compacted cluster formation of the cells. These biodegradable and biocompatible poly(aspartic acid)-based hydrogels are promising scaffolds for cell cultivation.

  9. Fabrication of Hyaluronan-Poly(vinylphosphonic acid-Chitosan Hydrogel for Wound Healing Application

    Directory of Open Access Journals (Sweden)

    Dang Hoang Phuc

    2016-01-01

    Full Text Available A new hydrogel made of hyaluronan, poly(vinylphosphonic acid, and chitosan (HA/PVPA/CS hydrogel was fabricated and characterized to be used for skin wound healing application. Firstly, the component ratio of hydrogel was studied to optimize the reaction effectiveness. Next, its microstructure was observed by light microscope. The chemical interaction in hydrogel was evaluated by nuclear magnetic resonance spectroscopy and Fourier transform-infrared spectroscopy. Then, a study on its degradation rate was performed. After that, antibacterial activity of the hydrogel was examined by agar diffusion method. Finally, in vivo study was performed to evaluate hydrogel’s biocompatibility. The results showed that the optimized hydrogel had a three-dimensional highly porous structure with the pore size ranging from about 25 µm to less than 125 µm. Besides, with a degradation time of two weeks, it could give enough time for the formation of extracellular matrix framework during remodeling stages. Furthermore, the antibacterial test showed that hydrogel has antimicrobial activity against E. coli. Finally, in vivo study indicated that the hydrogel was not rejected by the immune system and could enhance wound healing process. Overall, HA/PVPA/CS hydrogel was successfully fabricated and results implied its potential for wound healing applications.

  10. Osteochondral defect repair using a polyvinyl alcohol-polyacrylic acid (PVA-PAAc) hydrogel.

    Science.gov (United States)

    Bichara, David A; Bodugoz-Sentruk, Hatice; Ling, Doris; Malchau, Erik; Bragdon, Charles R; Muratoglu, Orhun K

    2014-08-01

    Poly(vinyl alcohol) (PVA) hydrogels can be candidates for articular cartilage repair due to their high water content. We synthesized a PVA-poly(acrylic acid) (PAAc) hydrogel formulation and determined its ability to function as a treatment option for condylar osteochondral (OC) defects in a New Zealand white rabbit (NZWR) model for 12 weeks and 24 weeks. In addition to hydrogel OC implants, tensile bar-shaped hydrogels were also implanted subcutaneously to evaluate changes in mechanical properties as a function of in vivo duration. There were no statistically significant differences (p > 0.05) in the water content measured in the OC hydrogel implant that was harvested after 12 weeks and 24 weeks, and non-implanted controls. There were no statistically significant differences (p > 0.05) in the break stress, strain at break or modulus of the tensile bars either between groups. Histological analysis of the OC defect, synovial capsule and fibrous tissue around the tensile bars determined hydrogel biocompatibility. Twelve-week hydrogels were found to be in situ flush with the articular cartilage; meniscal tissue demonstrated an intact surface. Twenty-four week hydrogels protruded from the defect site due to lack of integration with subchondral tissue, causing fibrillation to the meniscal surface. Condylar micro-CT scans ruled out osteolysis and bone cysts of the subchondral bone, and no PVA-PAAc hydrogel contents were found in the synovial fluid. The PVA-PAAc hydrogel was determined to be fully biocompatible, maintained its properties over time, and performed well at the 12 week time point. Physical fixation of the PVA-PAAc hydrogel to the subchondral bone is required to ensure long-term performance of hydrogel plugs for OC defect repair.

  11. Poly (γ-glutamic acid)/beta-TCP nanocomposites via in situ copolymerization: Preparation and characterization.

    Science.gov (United States)

    Shu, Xiu-Lin; Shi, Qing-Shan; Feng, Jin; Yang, Yun-Hua; Zhou, Gang; Li, Wen-Ru

    2016-07-01

    A series biodegradable poly (γ-glutamic acid)/beta-tricalcium phosphate (γ-PGA/TCP) nanocomposites were prepared which were composed of poly-γ-glutamic acid polymerized in situ with β-tricalcium phosphate and physiochemically characterized as bone graft substitutes. The particle size via dynamic light scattering, the direct morphological characterization via transmission electron microscopy and field emission scanning electron microscope, which showed that γ-PGA and β-TCP were combined compactly at 80℃, and the γ-PGA/TCP nanocomposites had homogenous and nano-sized grains with narrow particle size distributions. The water uptake and retention abilities, in vitro degradation properties, cytotoxicity in the simulated medium, and protein release of these novel γ-PGA/TCP composites were investigated. Cell proliferation in composites was nearly twice than β-TCP when checked in vitro using MC3T3 cell line. We also envision the potential use of γ-PGA/TCP systems in bone growth factor or orthopedic drug delivery applications in future bone tissue engineering applications. These observations suggest that the γ-PGA/TCP are novel nanocomposites with great potential for application in the field of bone tissue engineering. © The Author(s) 2016.

  12. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    Science.gov (United States)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-11-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm2 at 0.019 V, respectively.

  13. A flexible micro biofuel cell utilizing hydrogel containing ascorbic acid

    International Nuclear Information System (INIS)

    Goto, Hideaki; Fukushi, Yudai; Nishioka, Yasushiro

    2014-01-01

    This paper reports on a biofuel cell with a dimension of 13×24 mm 2 fabricated on a flexible polyimide substrate. I its porous carbon-coated platinum (Pt) electrodes of 3 mm in width and 10 mm in length were fabricated using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Pt electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. It utilizes a solidified ascorbic acid (AA) aqueous solution in an agarose hydrogel to increase the portability. The maximum power and power density for the biofuel cell with the fuel unit containing 100 mM AA were 0.063 μW and 0.21 μW/cm 2 at 0.019 V, respectively

  14. Superabsorbent Prepared by Radiation Induced Graft Copolymerization of Acrylic Acid onto Cassava Starch. Chapter 18

    Energy Technology Data Exchange (ETDEWEB)

    Suwanmala, P.; Tangthong, T.; Hemvichian, K. [Thailand Institute of Nuclear Technology (Thailand)

    2014-07-15

    Superabsorbent was synthesized by radiation induced graft polymerization of acrylic acid onto cassava starch. Parameters such as the absorbed dose and the amount of monomer were investigated in order to determine the optimum conditions for the grafting polymerization. Water retention, germination percentage, and germination energy were also determined in order to evaluate the possibility of superabsorbent in agricultural applications, especially in arid regions. The graft copolymer was characterized by the Fourier transform infrared spectroscopy (FTIR). Results indicated that the sand mixed with 0.1% wt superabsorbent could absorb more water than the sand without superabsorbent. The germination energy of corn seeds mixed with 0.5% superabsorbent was obviously higher than those without superabsorbent. These experimental results showed that the superabsorbent has considerable effects on seed germination and the growth of young plants. (author)

  15. Hydrogels from Amorphous Calcium Carbonate and Polyacrylic Acid: Bio-Inspired Materials for "Mineral Plastics".

    Science.gov (United States)

    Sun, Shengtong; Mao, Li-Bo; Lei, Zhouyue; Yu, Shu-Hong; Cölfen, Helmut

    2016-09-19

    Given increasing environmental issues due to the large usage of non-biodegradable plastics based on petroleum, new plastic materials, which are economic, environmentally friendly, and recyclable are in high demand. One feasible strategy is the bio-inspired synthesis of mineral-based hybrid materials. Herein we report a facile route for an amorphous CaCO3 (ACC)-based hydrogel consisting of very small ACC nanoparticles physically cross-linked by poly(acrylic acid). The hydrogel is shapeable, stretchable, and self-healable. Upon drying, the hydrogel forms free-standing, rigid, and transparent objects with remarkable mechanical performance. By swelling in water, the material can completely recover the initial hydrogel state. As a matrix, thermochromism can also be easily introduced. The present hybrid hydrogel may represent a new class of plastic materials, the "mineral plastics". © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Conversion of Lignocellulosic Bagasse Biomass into Hydrogel

    Directory of Open Access Journals (Sweden)

    Farzaneh Amiri

    2016-11-01

    Full Text Available In recent years, the main objective of developing new hydrogel systems has been to convert biomass into environmentally-friendly hydrogels. Hybrid hydrogels are usually prepared by graft copolymerization of acrylic monomers onto natural polymers or biomass. In this study, sugarcane bagasse was used to prepare semi-synthetic hybrid hydrogels without delignification, which is a costly and timeconsuming process. Sugarcane bagasse as a source of polysaccharide was modified using polymer microgels based on acrylic monomers such as acrylic acid, acrylamide and 2-acrylamido-2-methyl propane sulfonic acid which were prepared through inverse emulsion polymerization. By this process, biomass as a low-value by-product was converted into a valuable semi-synthetic hydrogel. In the following, the effect of latex type¸ the aqueous-to-organic phase ratio in the polymer latex, time and temperature of modification reaction on the swelling capacity of the hybrid hydrogel were evaluated. The chemical reaction between sugarcane bagasse and acrylic latex was carried out during heating of the modified bagasse which led to obtain a semisynthetic hydrogel with 60% natural components and 40% synthetic components. Among the latexes with different structures, poly(AA-NaAA-AM-AMPS was the most suitable polymer latex for the conversion of biomass into hydrogel. The bagasse modified with this latex had a water absorption capacity up to 112 g/g, while the water absorption capacity of primary sugarcane bagasse was only equal to 3.6 g/g. The prepared polymer hydrogels were characterized using Fourier transform infrared spectroscopy (FTIR, dynamic-mechanical thermal analysis (DMTA, thermal gravimetric analysis (TGA, scanning electron microscopy (SEM and determination of the amount of swelling capacity.

  17. 3D bioprinting of methacrylated hyaluronic acid (MeHA) hydrogel with intrinsic osteogenicity.

    Science.gov (United States)

    Poldervaart, Michelle T; Goversen, Birgit; de Ruijter, Mylene; Abbadessa, Anna; Melchels, Ferry P W; Öner, F Cumhur; Dhert, Wouter J A; Vermonden, Tina; Alblas, Jacqueline

    2017-01-01

    In bone regenerative medicine there is a need for suitable bone substitutes. Hydrogels have excellent biocompatible and biodegradable characteristics, but their visco-elastic properties limit their applicability, especially with respect to 3D bioprinting. In this study, we modified the naturally occurring extracellular matrix glycosaminoglycan hyaluronic acid (HA), in order to yield photo-crosslinkable hydrogels with increased mechanical stiffness and long-term stability, and with minimal decrease in cytocompatibility. Application of these tailor-made methacrylated hyaluronic acid (MeHA) gels for bone tissue engineering and 3D bioprinting was the subject of investigation. Visco-elastic properties of MeHA gels, measured by rheology and dynamic mechanical analysis, showed that irradiation of the hydrogels with UV light led to increased storage moduli and elastic moduli, indicating increasing gel rigidity. Subsequently, human bone marrow derived mesenchymal stromal cells (MSCs) were incorporated into MeHA hydrogels, and cell viability remained 64.4% after 21 days of culture. Osteogenic differentiation of MSCs occurred spontaneously in hydrogels with high concentrations of MeHA polymer, in absence of additional osteogenic stimuli. Addition of bone morphogenetic protein-2 (BMP-2) to the culture medium further increased osteogenic differentiation, as evidenced by increased matrix mineralisation. MeHA hydrogels demonstrated to be suitable for 3D bioprinting, and were printed into porous and anatomically shaped scaffolds. Taken together, photosensitive MeHA-based hydrogels fulfilled our criteria for cellular bioprinted bone constructs within a narrow window of concentration.

  18. 3D bioprinting of methacrylated hyaluronic acid (MeHA hydrogel with intrinsic osteogenicity.

    Directory of Open Access Journals (Sweden)

    Michelle T Poldervaart

    Full Text Available In bone regenerative medicine there is a need for suitable bone substitutes. Hydrogels have excellent biocompatible and biodegradable characteristics, but their visco-elastic properties limit their applicability, especially with respect to 3D bioprinting. In this study, we modified the naturally occurring extracellular matrix glycosaminoglycan hyaluronic acid (HA, in order to yield photo-crosslinkable hydrogels with increased mechanical stiffness and long-term stability, and with minimal decrease in cytocompatibility. Application of these tailor-made methacrylated hyaluronic acid (MeHA gels for bone tissue engineering and 3D bioprinting was the subject of investigation. Visco-elastic properties of MeHA gels, measured by rheology and dynamic mechanical analysis, showed that irradiation of the hydrogels with UV light led to increased storage moduli and elastic moduli, indicating increasing gel rigidity. Subsequently, human bone marrow derived mesenchymal stromal cells (MSCs were incorporated into MeHA hydrogels, and cell viability remained 64.4% after 21 days of culture. Osteogenic differentiation of MSCs occurred spontaneously in hydrogels with high concentrations of MeHA polymer, in absence of additional osteogenic stimuli. Addition of bone morphogenetic protein-2 (BMP-2 to the culture medium further increased osteogenic differentiation, as evidenced by increased matrix mineralisation. MeHA hydrogels demonstrated to be suitable for 3D bioprinting, and were printed into porous and anatomically shaped scaffolds. Taken together, photosensitive MeHA-based hydrogels fulfilled our criteria for cellular bioprinted bone constructs within a narrow window of concentration.

  19. Influence of retinoic acid on mesenchymal stem cell differentiation in amyloid hydrogels

    Directory of Open Access Journals (Sweden)

    Reeba Susan Jacob

    2015-12-01

    Full Text Available This paper presents data related to the research article “Self healing hydrogels composed of amyloid nano fibrils for cell culture and stem cell differentiation” [1]. Here we probed the collective influence of all-trans retinoic acid (RA and substrate properties (amyloid hydrogel on human mesenchymal stem cell (hMSC differentiation. Stem cells were cultured on soft amyloid hydrogels [1,2] in the presence and absence of matrix encapsulated RA. The cell morphology was imaged and assessed via quantification of circularity. Further immunostaining and quantitative real time PCR was used to quantify various markers of differentiation in the neuronal lineage.

  20. Synthesis and characterization of chitosan-graft-poly(acrylic acid)/rice husk ash hydrogels composites

    International Nuclear Information System (INIS)

    Rodrigues, Francisco H.A.; Lopes, Gabriel V.; Pereira, Antonio G.B.; Fajardo, Andre R.; Muniz, Edvani C.

    2011-01-01

    According to environmental concerns, super absorbent hydrogel composites were synthesized based on rice husk ash (RHA), an industrial waste, and Chitosan-graft-poly(acrylic acid). The WAXS and FTIR data confirmed the syntheses of hydrogel composites. The effect of crystalline or amorphous RHA on water uptake was investigated. It was found that the RHA in crystalline form induces higher water capacity (W eq ) of composites hydrogels due to the fact that the intra-interactions among silanol groups on RHA make available new sites in the polymer matrix, which could interact to water. (author)

  1. Synthesis and characterization of hyaluronic acid/human-like collagen hydrogels

    International Nuclear Information System (INIS)

    Zhang, Jingjing; Ma, Xiaoxuan; Fan, Daidi; Zhu, Chenhui; Deng, Jianjun; Hui, Junfeng; Ma, Pei

    2014-01-01

    Injectable hydrogel plays an important role in soft tissue filling and repair. We report an injectable hydrogel based on hyaluronic acid (HA) and human-like collagen (HLC), both with favorable biocompatibility and biodegradability. These two types of biomacromolecules were crosslinked with 1,4-butanediol diglycidyl ether to form a three-dimensional network. The redundant crosslinker was removed by dialysis and distillation. An HA-based hydrogel prepared by the same method was used as a control. The cytocompatibility was studied with a Cell Counting Kit-8 (CCK-8) test. Carbazole colorimetry was used to analyze the in vitro degradation rate. The histocompatibility was evaluated by hematoxylin and eosin (H and E) staining analysis and immunohistochemical analysis. The CCK-8 assay demonstrated that the HA/HLC hydrogel was less cytotoxic than the HA-based hydrogel and could promote baby hamster kidney cell (BHK) proliferation. The cell adhesion indicated that BHK could grow well on the surface of the materials and maintain good cell viability. The in vitro degradation test showed that the HA/HLC hydrogel had a longer degradation time and an excellent antienzyme ability. In vivo injection showed that there was little inflammatory response to HA/HLC after 1, 2, and 4 weeks. Therefore, the HA/HLC hydrogel is a promising biomaterial for soft tissue filling and repair. - Highlights: • Human-like collagen was used with hyaluronic acid to prepare soft tissue filling meterials. • 1,4-Butanediol diglycidyl ether (BDDE) was introduced to treat the hydrogels. • The addition of human-like collagen could improve the biological properties of hydrogels

  2. Synthesis and characterization of hyaluronic acid/human-like collagen hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingjing; Ma, Xiaoxuan, E-mail: xiaoxuanma@163.com; Fan, Daidi, E-mail: fandaidi@nwu.edu.cn; Zhu, Chenhui; Deng, Jianjun; Hui, Junfeng; Ma, Pei

    2014-10-01

    Injectable hydrogel plays an important role in soft tissue filling and repair. We report an injectable hydrogel based on hyaluronic acid (HA) and human-like collagen (HLC), both with favorable biocompatibility and biodegradability. These two types of biomacromolecules were crosslinked with 1,4-butanediol diglycidyl ether to form a three-dimensional network. The redundant crosslinker was removed by dialysis and distillation. An HA-based hydrogel prepared by the same method was used as a control. The cytocompatibility was studied with a Cell Counting Kit-8 (CCK-8) test. Carbazole colorimetry was used to analyze the in vitro degradation rate. The histocompatibility was evaluated by hematoxylin and eosin (H and E) staining analysis and immunohistochemical analysis. The CCK-8 assay demonstrated that the HA/HLC hydrogel was less cytotoxic than the HA-based hydrogel and could promote baby hamster kidney cell (BHK) proliferation. The cell adhesion indicated that BHK could grow well on the surface of the materials and maintain good cell viability. The in vitro degradation test showed that the HA/HLC hydrogel had a longer degradation time and an excellent antienzyme ability. In vivo injection showed that there was little inflammatory response to HA/HLC after 1, 2, and 4 weeks. Therefore, the HA/HLC hydrogel is a promising biomaterial for soft tissue filling and repair. - Highlights: • Human-like collagen was used with hyaluronic acid to prepare soft tissue filling meterials. • 1,4-Butanediol diglycidyl ether (BDDE) was introduced to treat the hydrogels. • The addition of human-like collagen could improve the biological properties of hydrogels.

  3. Nicotine-selective radiation-induced poly(acrylamide/maleic acid) hydrogels

    International Nuclear Information System (INIS)

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

    2001-01-01

    Nicotine-selective poly(acrylamide/maleic acid) (AAm/MA) hydrogels prepared by γ-irradiation were used in experiments on swelling, diffusion, and interactions of the pharmaceuticals nicotine, nicotinic acid, nicotinamide, and nikethamide. For AAm/MA hydrogel containing 60 mg maleic acid and irradiated at 5.2 kGy, the studies indicated that swelling increased in the following order; nicotine>nicotinamide>nikethamide>nicotinic acid>water. Diffusions of water and the pharmaceuticals within the hydrogels were found to be non-Fickian in character. AAm/MA hydrogel sorbed only nicotine and did not sorb nicotinamide, nikethamide and nicotinic acid in the binding experiments. S-type adsorption in Giles's classification system was observed. Some binding and thermodynamic parameters for AAm/MA hydrogel-nicotine system were calculated using the Scatchard method. The values of adsorption heat and free energy of this system were found to be negative whereas adsorption entropy was found to be positive. (author)

  4. Fabrication and mechanical characterization of graphene oxide-reinforced poly (acrylic acid)/gelatin composite hydrogels

    Science.gov (United States)

    Faghihi, Shahab; Gheysour, Mahsa; Karimi, Alireza; Salarian, Reza

    2014-02-01

    Hydrogels have found many practical uses in drug release, wound dressing, and tissue engineering. However, their applications are restricted due to their weak mechanical properties. The role of graphene oxide nanosheets (GONS) as reinforcement agent in poly (acrylic acid) (PAA)/Gelatin (Gel) composite hydrogels is investigated. Composite hydrogels are synthesized by thermal initiated redox polymerization method. Samples are then prepared with 20 and 40 wt. % of PAA, an increasing amount of GONS (0.1, 0.2, and 0.3 wt. %), and a constant amount of Gel. Subsequently, cylindrical hydrogel samples are subjected to a series of compression tests in order to measure their elastic modulus, maximum stress and strain. The results exhibit that the addition of GONS increases the Young's modulus and maximum stress of hydrogels significantly as compared with control (0.0 wt. % GONS). The highest Young's modulus is observed for hydrogel with GO (0.2 wt. %)/PAA (20 wt. %), whereas the highest maximum stress is detected for GO (0.2 wt. %)/PAA (40 wt. %) specimen. The addition of higher amounts of GONS leads to a decrease in the maximum stress of the hydrogel GO (0.3 wt. %)/PAA (40 wt. %). No significant differences are detected for the maximum strain among the hydrogel samples, as the amount of GONS increased. These results suggest that the application of GONS could be used to improve mechanical properties of hydrogel materials. This study may provide an alternative for the fabrication of low-cost graphene/polymer composites with enhanced mechanical properties beneficial for tissue engineering applications.

  5. Synthesis of superabsorbent hydrogel by radiation crosslinking of acrylic acid, semi-refined kappa-carrageenan and sugarcane bagasse blend

    International Nuclear Information System (INIS)

    Jizmundo, Leonie-Lou Dominguez

    2015-04-01

    Superabsorbent hydrogels have three-dimensional networks that enable it to exhibit great water absorption capacity leading to its promising applications. However, existing commercial hydrogels are mainly acrylic acid which causes environmental problems. In this study, the incorporation of agricultural waste as filler and polysaccharide from natural sources as binder for the production of superabsorbent hydrogel was done to reduce the use of acrylic acid as well as its environmental impact while adding value to the incorporated materials. A series of superabsorbent hydrogel with the blend of acrylic acid, semi-refined kappa carrageenan and sugarcane bagasse were synthesized by radiation crosslinking. The gel fraction and swelling capacity of the hydrogels were determined and studied. The characterizations were facilitated by Fourier transform infrared spectroscopy technique (FTIR) and Thermogravimetric Analysis (TGA). In the results obtained from analyses, the characteristic peaks of acrylic acid and sugarcane bagasse were observed in the FTIR spectra and the three step peaks if synthesized hydrogel in its TGA implies an improvement in thermal stability of the product. The synthesized superabsorbent hydrogel blends had exhibited comparable gel fraction to that of the polyacrylic acid hydrogel, had great swelling capacity, and achieved equilibrium degree of swelling within 72-96 hours. The optimum synthesized superabsorbent hydrogel is 3% semi-refined kappa-carrageenan, 3% sugarcane bagasse, 15% acrylic acid neutralize up to 50% and irradiated at 15kGy dose which exhibited a swelling of 599.53 and gel fraction of 39.73. (author)

  6. Ibuprofen-conjugated hyaluronate/polygalacturonic acid hydrogel for the prevention of epidural fibrosis.

    Science.gov (United States)

    Lin, Cheng-Yi; Peng, Hsiu-Hui; Chen, Mei-Hsiu; Sun, Jui-Sheng; Chang, Chih-Ju; Liu, Tse-Ying; Chen, Ming-Hong

    2016-05-01

    The formation of fibrous tissue is part of the natural healing response following a laminectomy. Severe scar tissue adhesion, known as epidural fibrosis, is a common cause of failed back surgery syndrome. In this study, by combining the advantages of drug treatment with a physical barrier, an ibuprofen-conjugated crosslinkable polygalacturonic acid and hyaluronic acid hydrogel was developed for epidural fibrosis prevention. Conjugation was confirmed and measured by 1D(1)H NMR spectroscopy.In vitroanalysis showed that the ibuprofen-conjugated polygalacturonic acid-hyaluronic acid hydrogel showed low cytotoxicity. In addition, the conjugated ibuprofen decreased prostaglandin E2production of the lipopolysaccharide-induced RAW264.7 cells. Histological data inin vivostudies indicated that the scar tissue adhesion of laminectomized male adult rats was reduced by the application of our ibuprofen-conjugated polygalacturonic acid-hyaluronic acid hydrogel. Its use also reduced the population of giant cells and collagen deposition of scar tissue without inducing extensive cell recruitment. The results of this study therefore suggest that the local delivery of ibuprofenviaa polygalacturonic acid-hyaluronic acid-based hydrogel reduces the possibility of epidural fibrosis. © The Author(s) 2016.

  7. Improving the Performances of Poly(vinylphosphonic acid) by Compositing or Copolymerization with Poly(4-(α-methyl)vinyl-1H-1,2,3-triazole)

    International Nuclear Information System (INIS)

    Han, Shuaiyuan; Yue, Baohua; Yan, Liuming

    2014-01-01

    Graphical abstract: - Highlights: • Poly(4-(α-methyl)vinyl-1H-1,2,3-triazole) is synthesized • PVPA/PMVTri polymeric composite proton conducting membranes are prepared • The proton conductivity of PVPA is improved by compositing with PMVTri • The water resistance of PVPA is improved by compositing with PMVTri • The oxidative stability is greatly improved - Abstract: The poly(vinylphosphonic acid) (PVPA), poly(4-(α-methyl)vinyl-1H-1,2,3-triazole) (PMVTri), and poly(VPA-co-MVTri) were synthesized, and proton exchange membranes were prepared based on the acid-base polymeric composite of PVPA and PMVTri, and acid-base amphoteric copolymer of poly(VPA-co-MVTri). The overall performances of PVPA, proton conductivity, thermal and oxidative stability, and water resistance, are greatly improved by compositing of PMVTri or copolymerization with 4-(α-methyl)vinyl-1H-1,2,3-triazole (MVTri). About four or eight folds improvement in maximum proton conductivity was observed in the polymeric composite of PVPA/PMVTri or acid-base amphoteric copolymer poly(VPA-co-MVTri) because of the redistribution of ions in the heterostructures of PVPA and PMVTri, respectively, compared with the pristine PVPA. At the same time, the oxidative stability and the water resistance of PVPA were also greatly improved attributing to the absent of α-H in the main chain of PMVTri and the acid-base interaction between the phosphonic acid groups and the triazolyl groups, respectively

  8. Removal of some basic dyes by poly (Vinyl Alcohol/ acrylic acid)Hydrogel

    International Nuclear Information System (INIS)

    Hegazy, S.A.; Abdel-AAl, S.E.; Abdel-Rehim, H.A.; Khalifa, N.A.; El-Hosseiny, E.M.

    2000-01-01

    A study has made on the preparation and properties of poly (vinyl alcohol/ acrylic acid) hydrogel for the purpose of removal of cationic dyes from aqueous solutions. The effect of dose and monomer concentration on the uptake property of the hydrogel toward dye was studied. The uptake of basic methylene blue-9 dye with PVA/AAc was studied by the batch adsorption technique. The effect of pH on the dye uptake was demonstrated to find out that the suitable pH for maximum uptake occurred at pH 5. It was observed that as the concentration of dye is increased the dye uptake decreased. Furthermore, the uptake of dye by hydrogels increased as the temperature was elevated. The recovery of dye adsorbed is possible by treating the hydrogel with 5% HCl. The results obtained suggested this hydrogel possessed good removal properties towards basic methylene blue-9 dye, and this suggests that such hydrogels could be acceptable for practical uses

  9. Synthesis and characterization of zinc chloride containing poly(acrylic acid) hydrogel by gamma irradiation

    International Nuclear Information System (INIS)

    Park, Jong-Seok; Kuang, Jia; Gwon, Hui-Jeong; Lim, Youn-Mook; Jeong, Sung-In; Shin, Young-Min; Seob Khil, Myung; Nho, Young-Chang

    2013-01-01

    In this study, the characterization of zinc chloride incorporated into a poly(acrylic acid) (PAAc) hydrogel prepared by gamma-ray irradiation was investigated. Zinc chloride powder with different concentrations was dissolved in the PAAc solution, and it was crosslinked with gamma-ray irradiation. The effects of various parameters such as zinc ion concentration and irradiation doses on characteristics of the hydrogel formed were investigated in detail for obtaining an antibacterial wound dressing. In addition, the gel content, pH-sensitive (pH 4 or 7) swelling ratio, and UV–vis absorption spectra of the zinc particles in the hydrogels were characterized. Moreover, antibacterial properties of these new materials against Staphylococcus aureus and Escherichia coli strains were observed on solid growth media. The antibacterial tests indicated that the zinc chloride containing PAAc hydrogels have good antibacterial activity. - Highlights: • The characterization of zinc chloride containing PAA hydrogel was investigated. • The gel content increased with an increase in absorbed dose up to 75 kGy. • Finally, the zinc chloride based hydrogels have an antibacterial activity

  10. Controlled Pesticide Release from Porous Composite Hydrogels Based on Lignin and Polyacrylic Acid

    Directory of Open Access Journals (Sweden)

    Yajie Sun

    2016-01-01

    Full Text Available For the controlled release of pesticides, a novel composite porous hydrogel (LBPAA was prepared based on lignin and polyacrylic acid for use as the support frame of a pore structure for water delivery. The LBPAA was analyzed to determine its water-swelling and slow release properties. The controlled release properties of LBPAA were evaluated through experiments in relation to the cumulative release of pesticides, with particular emphasis on environmental effects and release models. The porous LBPAA hydrogel showed improved properties compared to polyacrylic acid, and could therefore be considered an efficient material for application in controlled release systems in agriculture.

  11. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Tan, Huaping, E-mail: hptan@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Hu, Xiaohong [School of Material Engineering, Jinling Institute of Technology, Nanjing (China)

    2015-11-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion.

  12. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

    International Nuclear Information System (INIS)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

    2015-01-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion

  13. The adsorption of Pb(sup2+) and Cu(sup2+) onto gum ghatti-grafted poly(acrylamide-co-acrylonitrile) biodegradable hydrogel: isotherms and kinetic models

    CSIR Research Space (South Africa)

    Mittal, H

    2015-01-01

    Full Text Available A biodegradable hydrogel polymer of gum ghatti (Gg) with a copolymer mixture of acrylamide (AAm) and acrylonitrile (AN) was synthesized using the free-radical graft copolymerization technique. The effect of graft copolymerization on the surface area...

  14. Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

    International Nuclear Information System (INIS)

    Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd

    2014-01-01

    The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier

  15. Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat [Faculty of Science and Technology, University Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Amin, Mohd. Cairul Iqbal Mohd [Faculty of Pharmacy, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur (Malaysia)

    2014-09-03

    The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.

  16. Flocculation and adsorption properties of biodegradable gum-ghatti-grafted poly(acrylamide-co-methacrylic acid) hydrogels

    CSIR Research Space (South Africa)

    Mittal, H

    2015-01-01

    Full Text Available This study reports the microwave-assisted synthesis of gum-ghatti (Gg)-grafted poly(acrylamide-co-methacrylic acid) (AAm-co-MAA) hydrogels for the development of biodegradable flocculants and adsorbents. The synthesized hydrogels were characterized...

  17. Investigation on Au-nano incorporated pH-sensitive (itaconic acid/acrylic acid/triethylene glycol) based polymeric biocompatible hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Sakthivel, M., E-mail: msakthi81986@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 046, Tamilnadu (India); Department of Chemistry, Ganadipathy Tulsi' s Jain Engineering College, Kaniyambadi, Vellore 632 102, Tamilnadu (India); Franklin, D.S., E-mail: loyolafrank@yahoo.co.in [Department of Chemistry, C. Abdul Hakeem College of Engineering and Technology, Melvisharam 632509, Tamilnadu (India); Sudarsan, S., E-mail: srsudarsan29@gmail.com [Department of Chemistry, Periyar University, Salem 636011, Tamilnadu (India); Chitra, G., E-mail: chitramuralikrishnan@gmail.com [Department of Chemistry, Periyar University, Salem 636011, Tamilnadu (India); Guhanathan, S., E-mail: sai_gugan@yahoo.com [PG & Research Department of Chemistry, Muthurangam Government Arts College, Vellore 632 002, Tamilnadu (India)

    2017-06-01

    The pH-sensitive gold nano hydrogel based on itaconic acid, acrylic acid and triethylene glycol (GIAT) has been prepared by free radical polymerization viz. organic solventless approach with different monomer ratios. The nature of bonding and structural identification of GIAT hydrogels were characterized by FT-IR spectroscopy. The surface morphology of gold gel was examined using scanning electron microscopy (SEM). In addition, transmission electron microscopy (TEM) was used to identify the size of gold nano particles. The in vitro biocompatibility of GIAT hydrogel has been evaluated in 3T3 fibroblast cell lines. The obtained results show that gold nano particle incorporated hydrogel possess ~ 99% of cell proliferation. Followed by, the impact of gold nano particles on swelling, surface morphology was studied. The consecutive preparation of hydrogel, effect of different pH conditions, and stoichiometry of monomeric units have also been discussed. The degree of swelling was measured in carbonate buffer solutions for 24 h period with varying pH such as 1.2, 6.0, 7.4 and 10.0. The obtained results showed that the stoichiometry of itaconic acid and gold nano particles plays an essential role in modifying the nature of GIAT polymeric hydrogels. In conclusion, promising Au-nano incorporated pH-sensitive bio polymeric hydrogels were prepared and characterized. The unique properties of these Au-nano hydrogel make them attractive use in biomedical applications. - Highlights: • Itaconic acid based hydrogels were developed viz. greener organic solvent less approach. • The enhanced equilibrium swelling at acidic and basic medium was observed for nano-Au-incorporated nano composite hydrogels. • The prepared GIAT hydrogel showed ~ 99% of cell proliferation. • This kind of pH-sensitive polymeric hydrogels may be useful for controlled drug delivery system.

  18. Investigation on Au-nano incorporated pH-sensitive (itaconic acid/acrylic acid/triethylene glycol) based polymeric biocompatible hydrogels

    International Nuclear Information System (INIS)

    Sakthivel, M.; Franklin, D.S.; Sudarsan, S.; Chitra, G.; Guhanathan, S.

    2017-01-01

    The pH-sensitive gold nano hydrogel based on itaconic acid, acrylic acid and triethylene glycol (GIAT) has been prepared by free radical polymerization viz. organic solventless approach with different monomer ratios. The nature of bonding and structural identification of GIAT hydrogels were characterized by FT-IR spectroscopy. The surface morphology of gold gel was examined using scanning electron microscopy (SEM). In addition, transmission electron microscopy (TEM) was used to identify the size of gold nano particles. The in vitro biocompatibility of GIAT hydrogel has been evaluated in 3T3 fibroblast cell lines. The obtained results show that gold nano particle incorporated hydrogel possess ~ 99% of cell proliferation. Followed by, the impact of gold nano particles on swelling, surface morphology was studied. The consecutive preparation of hydrogel, effect of different pH conditions, and stoichiometry of monomeric units have also been discussed. The degree of swelling was measured in carbonate buffer solutions for 24 h period with varying pH such as 1.2, 6.0, 7.4 and 10.0. The obtained results showed that the stoichiometry of itaconic acid and gold nano particles plays an essential role in modifying the nature of GIAT polymeric hydrogels. In conclusion, promising Au-nano incorporated pH-sensitive bio polymeric hydrogels were prepared and characterized. The unique properties of these Au-nano hydrogel make them attractive use in biomedical applications. - Highlights: • Itaconic acid based hydrogels were developed viz. greener organic solvent less approach. • The enhanced equilibrium swelling at acidic and basic medium was observed for nano-Au-incorporated nano composite hydrogels. • The prepared GIAT hydrogel showed ~ 99% of cell proliferation. • This kind of pH-sensitive polymeric hydrogels may be useful for controlled drug delivery system.

  19. Depletion of abundant plasma proteins by poly(N-isopropylacrylamide-acrylic acid) hydrogel particles

    DEFF Research Database (Denmark)

    Such-Sanmartín, Gerard; Ventura-Espejo, Estela; Jensen, Ole N

    2014-01-01

    the application of pH-sensitive poly(N-isopropylacrylamide-acrylic acid) hydrogel particles for removal of abundant plasma proteins, prior to proteome analysis by MS. Protein depletion occurs by two separate mechanisms: (1) hydrogel particles incubated with low concentrations of plasma capture abundant proteins...... proteins are released and recovered in the eluate. We developed a series of distinct depletion protocols that proved useful for sample depletion and fractionation and facilitated targeted analysis of putative biomarkers such as IGF1-2, IBP2-7, ALS, KLK6-7, ISK5, and PLF4 by selected reaction monitoring...

  20. Poly(ethylene glycol) (PEG)-lactic acid nanocarrier-based degradable hydrogels for restoring the vaginal microenvironment

    Science.gov (United States)

    Rajan, Sujata Sundara; Turovskiy, Yevgeniy; Singh, Yashveer; Chikindas, Michael L.; Sinko, Patrick J.

    2014-01-01

    Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH 7.4) and acetate buffer (AB, pH 4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%–14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV. PMID:25223229

  1. Poly(vinyl alcohol)-Tannic Acid Hydrogels with Excellent Mechanical Properties and Shape Memory Behaviors.

    Science.gov (United States)

    Chen, Ya-Nan; Peng, Lufang; Liu, Tianqi; Wang, Yaxin; Shi, Shengjie; Wang, Huiliang

    2016-10-12

    Shape memory hydrogels have promising applications in a wide variety of fields. Here we report the facile fabrication of a novel type of shape memory hydrogels physically cross-linked with both stronger and weaker hydrogen bonding (H-bonding). Strong multiple H-bonding formed between poly(vinyl alcohol) (PVA) and tannic acid (TA) leads to their coagulation when they are physically mixed at an elevated temperature and easy gelation at room temperature. The amorphous structure and strong H-bonding endow the PVA-TA hydrogels with excellent mechanical properties, as indicated by their high tensile strengths (up to 2.88 MPa) and high elongations (up to 1100%). The stronger H-bonding between PVA and TA functions as the "permanent" cross-link and the weaker H-bonding between PVA chains as the "temporary" cross-link. The reversible breakage and formation of the weaker H-bonding imparts the PVA-TA hydrogels with excellent temperature-responsive shape memory. Wet and dried hydrogel samples with a deformed or elongated shape can recover to their original shapes when immersed in 60 °C water in a few seconds or at 125 °C in about 2.5 min, respectively.

  2. Preparation and characterization of polyacrylamide-modified kaolinite containing poly [acrylic acid-co-methylene bisacrylamide] nanocomposite hydrogels

    DEFF Research Database (Denmark)

    Zaharia, Anamaria; Sarbu, Andrei; Radu, Anita-Laura

    2015-01-01

    Novel nanocomposite hydrogel structures based on cross-linked poly(acrylic acid) (PAA) and kaolinite (Kaol), modified with different loadings of polyacrylamide (PAAm), were prepared by inverse dispersion polymerization. Ceric ammonium nitrate as an initiator in the presence of nitric acid was used...... of Kaol particles in the polyacrylic acid matrix, thereby leading to enhanced interactions and furthermore to improved mechanical properties of the final hydrogels....

  3. Efficient removal of rhodamine 6G dye from aqueous solution using nickel sulphide incorporated polyacrylamide grafted gum karaya bionanocomposite hydrogel

    CSIR Research Space (South Africa)

    Kumar, N

    2016-02-01

    Full Text Available polymer of the Gk with the PAAm was synthesized using the graft co-polymerization technique. In the second step, the nickel sulphide nanoparticles were incorporated in situ within the hydrogel polymer matrix. The synthesized hydrogel nanocomposite...

  4. A novel multi-responsive polyampholyte composite hydrogel with excellent mechanical strength and rapid shrinking rate.

    Science.gov (United States)

    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). Copyright © 2010 Elsevier Inc. All rights reserved.

  5. Two-dimensional inverse opal hydrogel for pH sensing.

    Science.gov (United States)

    Xue, Fei; Meng, Zihui; Qi, Fenglian; Xue, Min; Wang, Fengyan; Chen, Wei; Yan, Zequn

    2014-12-07

    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.

  6. The synthesis and characterization of hydrogel chitosan-alginate with the addition of plasticizer lauric acid for wound dressing application

    Science.gov (United States)

    Izak Rudyardjo, Djony; Wijayanto, Setiawan

    2017-05-01

    The writers conducted a study about the synthesis and characterization of hydrogel chitosan-alginate by addition plasticizer lauric acid for wound dressing application. The purpose was to find out the impact of lauric acid concentration variation on hydrogel chitosan-alginate to get the best mechanical and physical properties to be applied as wound dressing in accordance with existing standards. This study used commercially chitosan from extract of shells crab, commercially-available alginate from the extract of sargassum sp, and commercial lauric acid from palm starch. The addition of lauric acid was aimed to repair mechanical properties of hydrogel. The composition of chitosan-alginate is 4:1 (v/v), while the lauric acid concentration variations are 0%, 1%, 2%, 3%, 4%, and 5% w/v. The characterization of mechanical properties test (Tensile strength and Elongation at break) at hydrogel showed the hydrogel chitosan-alginate-lauric acid have the characteristic which meets the standard of mechanical properties for human skin. The best performance of hydrogel chitosan-alginate-lauric acid was obtained by increasing luric acid concentration by 4%, which has a thickness value of 125.46±0.63 µm, elongation 28.89±1.01 %, tensile strength (9.01±0.65) MPa, and ability to absorb liquids (601.45 ±1.24) %.

  7. The self-crosslinking smart hyaluronic acid hydrogels as injectable three-dimensional scaffolds for cells culture.

    Science.gov (United States)

    Bian, Shaoquan; He, Mengmeng; Sui, Junhui; Cai, Hanxu; Sun, Yong; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

    2016-04-01

    Although the disulfide bond crosslinked hyaluronic acid hydrogels have been reported by many research groups, the major researches were focused on effectively forming hydrogels. However, few researchers paid attention to the potential significance of controlling the hydrogel formation and degradation, improving biocompatibility, reducing the toxicity of exogenous and providing convenience to the clinical operations later on. In this research, the novel controllable self-crosslinking smart hydrogels with in-situ gelation property was prepared by a single component, the thiolated hyaluronic acid derivative (HA-SH), and applied as a three-dimensional scaffold to mimic native extracellular matrix (ECM) for the culture of fibroblasts cells (L929) and chondrocytes. A series of HA-SH hydrogels were prepared depending on different degrees of thiol substitution (ranging from 10 to 60%) and molecule weights of HA (0.1, 0.3 and 1.0 MDa). The gelation time, swelling property and smart degradation behavior of HA-SH hydrogel were evaluated. The results showed that the gelation and degradation time of hydrogels could be controlled by adjusting the component of HA-SH polymers. The storage modulus of HA-SH hydrogels obtained by dynamic modulus analysis (DMA) could be up to 44.6 kPa. In addition, HA-SH hydrogels were investigated as a three-dimensional scaffold for the culture of fibroblasts cells (L929) and chondrocytes cells in vitro and as an injectable hydrogel for delivering chondrocytes cells in vivo. These results illustrated that HA-SH hydrogels with controllable gelation process, intelligent degradation behavior, excellent biocompatibility and convenient operational characteristics supplied potential clinical application capacity for tissue engineering and regenerative medicine. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. pH-responsive poly(aspartic acid) hydrogel-coated magnetite nanoparticles for biomedical applications.

    Science.gov (United States)

    Vega-Chacón, Jaime; Arbeláez, María Isabel Amaya; Jorge, Janaina Habib; Marques, Rodrigo Fernando C; Jafelicci, Miguel

    2017-08-01

    A novel multifunctional nanosystem formed by magnetite nanoparticles coated with pH-responsive poly(aspartic acid) hydrogel was developed. Magnetite nanoparticles (Fe 3 O 4 ) have been intensively investigated for biomedical applications due to their magnetic properties and dimensions similar to the biostructures. Poly(aspartic acid) is a water-soluble, biodegradable and biocompatible polymer, which features makes it a potential candidate for biomedical applications. The nanoparticles surface modification was carried out by crosslinking polysuccinimide on the magnetite nanoparticles surface and hydrolyzing the succinimide units in mild alkaline medium to obtain the magnetic poly(aspartic acid) hydrogel. The surface modification in each step was confirmed by DRIFTS, TEM and zeta potential measurements. The hydrodynamic diameter of the nanosystems decreases as the pH value decreases. The nanosystems showed high colloidal stability in water and no cytotoxicity was detected, which make these nanosystems suitable for biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Cytotoxicity and metal ions removal using antibacterial biodegradable hydrogels based on N-quaternized chitosan/poly(acrylic acid).

    Science.gov (United States)

    Mohamed, Riham R; Elella, Mahmoud H Abu; Sabaa, Magdy W

    2017-05-01

    Physically crosslinked hydrogels resulted from interaction between N,N,N-trimethyl chitosan chloride (N-Quaternized Chitosan) (NQC) and poly(acrylic acid) (PAA) were synthesized in different weight ratios (3:1), (1:1) and (1:3) taking the following codes Q3P1, Q1P1 and Q1P3, respectively. Characterization of the mentioned hydrogels was done using several analysis tools including; FTIR, XRD, SEM, TGA, biodegradation in simulated body fluid (SBF) and cytotoxicity against HepG-2 liver cancer cells. FTIR results proved that the prepared hydrogels were formed via electrostatic and H-bonding interactions, while XRD patterns proved that the prepared hydrogels -irrespective to their ratios- were more crystalline than both matrices NQC and PAA. TGA results, on the other hand, revealed that Q1P3 hydrogel was the most thermally stable compared to the other two hydrogels (Q3P1 and Q1P1). Biodegradation tests in SBF proved that these hydrogels were more biodegradable than the native chitosan. Examination of the prepared hydrogels for their potency in heavy metal ions removal revealed that they adsorbed Fe (III) and Cd (II) ions more than chitosan, while they adsorbed Cr (III), Ni (II) and Cu (II) ions less than chitosan. Moreover, testing the prepared hydrogels as antibacterial agents towards several Gram positive and Gram negative bacteria revealed their higher antibacterial activity as compared with NQC when used alone. Evaluating the cytotoxic effect of these hydrogels on an in vitro human liver cancer cell model (HepG-2) showed their good cytotoxic activity towards HepG-2. Moreover, the inhibition rate increased with increasing the hydrogels concentration in the culture medium. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Thiol functionalized polymethacrylic acid-based hydrogel microparticles for oral insulin delivery.

    Science.gov (United States)

    Sajeesh, S; Vauthier, C; Gueutin, C; Ponchel, G; Sharma, Chandra P

    2010-08-01

    In the present study thiol functionalized polymethacrylic acid-polyethylene glycol-chitosan (PCP)-based hydrogel microparticles were utilized to develop an oral insulin delivery system. Thiol modification was achieved by grafting cysteine to the activated surface carboxyl groups of PCP hydrogels (Cys-PCP). Swelling and insulin loading/release experiments were conducted on these particles. The ability of these particles to inhibit protease enzymes was evaluated under in vitro experimental conditions. Insulin transport experiments were performed on Caco-2 cell monolayers and excised intestinal tissue with an Ussing chamber set-up. Finally, the efficacy of insulin-loaded particles in reducing the blood glucose level in streptozotocin-induced diabetic rats was investigated. Thiolated hydrogel microparticles showed less swelling and had a lower insulin encapsulation efficiency as compared with unmodified PCP particles. PCP and Cys-PCP microparticles were able to inhibit protease enzymes under in vitro conditions. Thiolation was an effective strategy to improve insulin absorption across Caco-2 cell monolayers, however, the effect was reduced in the experiments using excised rat intestinal tissue. Nevertheless, functionalized microparticles were more effective in eliciting a pharmacological response in diabetic animal, as compared with unmodified PCP microparticles. From these studies thiolation of hydrogel microparticles seems to be a promising approach to improve oral delivery of proteins/peptides. Copyright 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. Stem Cell-Containing Hyaluronic Acid-Based Spongy Hydrogels for Integrated Diabetic Wound Healing.

    Science.gov (United States)

    da Silva, Lucília Pereira; Santos, Tírcia Carlos; Rodrigues, Daniel Barreira; Pirraco, Rogério Pedro; Cerqueira, Mariana Teixeira; Reis, Rui Luís; Correlo, Vitor Manuel; Marques, Alexandra Pinto

    2017-07-01

    The detailed pathophysiology of diabetic foot ulcers is yet to be established and improved treatments are still required. We propose a strategy that directs inflammation, neovascularization, and neoinnervation of diabetic wounds. Aiming to potentiate a relevant secretome for nerve regeneration, stem cells were precultured in hyaluronic acid-based spongy hydrogels under neurogenic/standard media before transplantation into diabetic mice full-thickness wounds. Acellular spongy hydrogels and empty wounds were used as controls. Re-epithelialization was attained 4 weeks after transplantation independently of the test groups, whereas a thicker and more differentiated epidermis was observed for the cellular spongy hydrogels. A switch from the inflammatory to the proliferative phase of wound healing was revealed for all the experimental groups 2 weeks after injury, but a significantly higher M2(CD163 + )/M1(CD86 + ) subtype ratio was observed in the neurogenic preconditioned group that also failed to promote neoinnervation. A higher number of intraepidermal nerve fibers were observed for the unconditioned group probably due to a more controlled transition from the inflammatory to the proliferative phase. Overall, stem cell-containing spongy hydrogels represent a promising approach to enhance diabetic wound healing by positively impacting re-epithelialization and by modulating the inflammatory response to promote a successful neoinnervation. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Radiation synthesis and characterization of pH-sensitive poly(acrylic acid-co-N-vinyl-2-pyrrolidone) hydrogels

    International Nuclear Information System (INIS)

    Yang Mingcheng; Zhu Jun; Song Weidong; Song Hongyan; Zhu Chengshen

    2006-01-01

    Hydrogels are crosslinked, three-dimensional hydrophilic polymer networks that swell but do not dissolve when brought into contact with water. These materials have been investigated extensively for potential applications in the biomedical field because of their similarities to soft tissues and their good tissue and blood compatibility. More specifically, pH-sensitive hydrogels are used for sustained gastro-intestinal drug delivery systems due to the intimacy and extended duration of contact. In this work, pH-sensitive copolymer hydrogels were prepared using acrylic acid and N-vinyl-2-pyrrolidone by γ-ray irradiation at ambient temperature. Effects of dose, monomer concentration, monomer composition, temperature and pH on the swelling ratio (SR) of the copolymer hydrogels were investigated in detail. The results show that SR of the copolymer hydrogels decreases with the monomer concentration and with the increase of absorbed dose. These copolymer hydrogels show good pH-sensitive behavior. These material shows no noticeable change in swelling at lower pH (pH<4) but an abrupt increase in swelling at higher pH (from pH7 to pH9.8). At pH 1.4, the SR of the copolymer hydrogels increases with the temperature. To the contrary, at pH 9.8, the SR of the copolymer hydrogels decreases with the temperature. (authors)

  13. Oral delivery of insulin using pH-sensitive hydrogels based on polyvinyl alcohol grafted with acrylic acid/methacrylic acid by radiation

    International Nuclear Information System (INIS)

    Nho, Young-Chang; Park, Sung-Eun; Kim, Hyung-Il; Hwang, Taek-Sung

    2005-01-01

    The pH-responsive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared via a two-step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto this poly(vinyl alcohol) hydrogels with subsequent irradiation (5-20 kGy). These graft hydrogels showed pH-sensitive swelling behavior. These hydrogels were used as carrier for the controlled release of insulin. The in vitro release of insulin was observed for the insulin-loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose

  14. Oral delivery of insulin using pH-sensitive hydrogels based on polyvinyl alcohol grafted with acrylic acid/methacrylic acid by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Young-Chang [Radiation Application Research Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of)]. E-mail: ycnho@kaeri.re.kr; Park, Sung-Eun [Radiation Application Research Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of); Kim, Hyung-Il [College of Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Hwang, Taek-Sung [College of Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2005-07-01

    The pH-responsive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared via a two-step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto this poly(vinyl alcohol) hydrogels with subsequent irradiation (5-20 kGy). These graft hydrogels showed pH-sensitive swelling behavior. These hydrogels were used as carrier for the controlled release of insulin. The in vitro release of insulin was observed for the insulin-loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose.

  15. An injectable and biodegradable hydrogel based on poly(α,β-aspartic acid) derivatives for localized drug delivery.

    Science.gov (United States)

    Lu, Caicai; Wang, Xiaojuan; Wu, Guolin; Wang, Jingjing; Wang, Yinong; Gao, Hui; Ma, Jianbiao

    2014-03-01

    An injectable hydrogel via hydrazone cross-linking was prepared under mild conditions without addition of cross-linker or catalyst. Hydrazine and aldehyde modified poly(aspartic acid)s were used as two gel precursors. Both of them are water-soluble and biodegradable polymers with a protein-like structure, and obtained by aminolysis reaction of polysuccinimide. The latter can be prepared by thermal polycondensation of aspartic acid. Hydrogels were prepared in PBS solution and characterized by different methods including gel content and swelling, Fourier transformed-infrared spectroscopy, and in vitro degradation experiment. A scanning electron microscope viewed the interior morphology of the obtained hydrogels, which showed porous three-dimensional structures. Different porous sizes were present, which could be well controlled by the degree of aldehyde substitution in precursor poly(aspartic acid) derivatives. The doxorubicin-loaded hydrogels were prepared and showed a pH-sensitive release profile. The release rate can be accelerated by decreasing the environmental pH from a physiological to a weak acidic condition. Moreover, the cell adhesion and growth behaviors on the hydrogel were studied and the polymeric hydrogel showed good biocompatibility. Copyright © 2013 Wiley Periodicals, Inc.

  16. Synthetic poly(amino acid) hydrogels with incorporated cell-adhesion peptides for tissue engineering

    Czech Academy of Sciences Publication Activity Database

    Studenovská, Hana; Vodička, Petr; Proks, Vladimír; Hlučilová, Jana; Motlík, Jan; Rypáček, František

    2010-01-01

    Roč. 4, č. 6 (2010), s. 454-463 ISSN 1932-6254 R&D Projects: GA AV ČR KJB400500801; GA MŠk 1M0538 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50450515 Keywords : polyamino acid * hydrogel * porosity Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.534, year: 2010

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

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Jiachuan [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Zheng, E-mail: lizheng_nx@163.com [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Xia, Wen; Yang, Ning; Gong, Jixian [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Jianfei, E-mail: zhangjianfei1960@126.com [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Qiao, Changsheng [Key Laboratory of Industrial Microbiology, Tianjin University of Science and Technology, Ministry of Education, Tianjin 300457 (China)

    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/–NH{sub 2} 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. - Highlights: • We prepared a biocompatible and degradable poly amino acids hydrogel via EDC

  18. Synthesis and characterization of kappaphycus seaweed-poly (acrylic) acid superabsorbent hydrogel for agricultural use

    International Nuclear Information System (INIS)

    Encinas, Angelica Marie E.

    2015-04-01

    The main objective of this research is to synthesize and characterize kappaphycus seaweed-poly (acrylic) acid superabsorbent hydrogel for agricultural use. The superabsorbent polymers (SAPs), KCSW: PAA hydrogels were synthesized by using gamma radiation technique from Cobalt-60 source at absorbed dose 0f 5, 10 and 15 kGy. The effect of absorbed dose, seaweed concentration, and concentration of acrylic acid on the degree of swelling was studied and optimum swelling conditions were established. Irradiated samples of 3% KCSW, 50% neutralized AAC at an absorbed dose of 10kGy gave the highest degree of swelling and gel fraction and were found to be suitable for application in the agriculture. Samples with different concentrations of acrylic acid were characterized using FTIR and TGA. The water retention experiment in sandy soil showed high water retention capacity of KCSW: PAA hydrogel at a value of 92% for a period of 7 days. Effect of the germination of mung bean showed very promising result of 78% germination.(author)

  19. Sorption of zinc by novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid

    International Nuclear Information System (INIS)

    Milosavljevic, Nedeljko B.; Ristic, Mirjana D.; Peric-Grujic, Aleksandra A.; Filipovic, Jovanka M.; Strbac, Svetlana B.; Rakocevic, Zlatko Lj.; Kalagasidis Krusic, Melina T.

    2011-01-01

    Highlights: → A removal of Zn 2+ ions by pH-sensitive Ch/IA/MAA hydrogel from aqueous solutions was studied. → SEM/EDX analysis and AFM surface topography indicate that sorption takes place on the surface of the hydrogel and in the bulk. → FTIR spectra of the Ch/IA/MAA hydrogel, free and Zn-loaded, indicate that -NH 2 , -OH and -COOH groups are involved in the sorption process. → The negative values of free energy and enthalpy indicated that the adsorption is spontaneous and exothermic one. → The adsorption capacities did not show any significant decrease after the third reuse cycle. - Abstract: Novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid were applied as adsorbents for the removal of Zn 2+ ions from aqueous solution. In batch tests, the influence of solution pH, contact time, initial metal ion concentration and temperature was examined. The sorption was found pH dependent, pH 5.5 being the optimum value. The adsorption process was well described by the pseudo-second order kinetic. The hydrogels were characterized by spectral (Fourier transform infrared-FTIR) and structural (SEM/EDX and atomic force microscopy-AFM) analyses. The surface topography changes were observed by atomic force microscopy, while the changes in surface composition were detected using phase imaging AFM. The negative values of free energy and enthalpy indicated that the adsorption is spontaneous and exothermic one. The best fitting isotherms were Langmuir and Redlich-Peterson and it was found that both linear and nonlinear methods were appropriate for obtaining the isotherm parameters. However, the increase of temperature leads to higher adsorption capacity, since swelling degree increased with temperature.

  20. Extended release of hyaluronic acid from hydrogel contact lenses for dry eye syndrome.

    Science.gov (United States)

    Maulvi, Furqan A; Soni, Tejal G; Shah, Dinesh O

    2015-01-01

    Current dry eye treatment includes delivering comfort enhancing agents to the eye via eye drops, but low residence time of eye drops leads to low bioavailability. Frequent administration leads to incompliance in patients, so there is a great need for medical device such as contact lenses to treat dry eye. Studies in the past have demonstrated the efficacy of hyaluronic acid (HA) in the treatment of dry eyes using eye drops. In this paper, we present two methods to load HA in hydrogel contact lenses, soaking method and direct entrapment. The contact lenses were characterized by studying their optical and physical properties to determine their suitability as extended wear contact lenses. HA-laden hydrogel contact lenses prepared by soaking method showed release up to 48 h with acceptable physical and optical properties. Hydrogel contact lenses prepared by direct entrapment method showed significant sustained release in comparison to soaking method. HA entrapped in hydrogels resulted in reduction in % transmittance, sodium ion permeability and surface contact angle, while increase in % swelling. The impact on each of these properties was proportional to HA loading. The batch with 200-μg HA loading showed all acceptable values (parameters) for contact lens use. Results of cytotoxicity study indicated the safety of hydrogel contact lenses. In vivo pharmacokinetics studies in rabbit tear fluid showed dramatic increase in HA mean residence time and area under the curve with lenses in comparison to eye drop treatment. The study demonstrates the promising potential of delivering HA through contact lenses for the treatment of dry eye syndrome.

  1. In situ assembly of fibrinogen/hyaluronic acid hydrogel via knob-hole interaction for 3D cellular engineering

    Directory of Open Access Journals (Sweden)

    Shengjie Huang

    2017-12-01

    Full Text Available Hyaluronic acid (HA-based hydrogels have applied widely for biomedical applications due to its biocompatibility and biodegradability. However, the use of initiators or crosslinkers during the hydrogel formation may cause cytotoxicity and thereby impair the biocompatibility. Inspired by the crosslinking mechanism of fibrin gel, a novel HA-based hydrogel was developed via the in situ supramolecular assembly based on knob-hole interactions between fibrinogen and knob-grafted HA (knob-g-HA in this study. The knob-grafted HA was synthesized by coupling knob peptides (GPRPAAC, a mimic peptide of fibrin knob A to HA via Michael addition. Then the translucent fibrinogen/knob-g-HA hydrogels were prepared by simply mixing the solutions of knob-g-HA and fibrinogen at the knob/hole ratio of 1.2. The rheological behaviors of the fibrinogen/knob-g-HA hydrogels with the fibrinogen concentrations of 50, 100 and 200 mg/mL were evaluated, and it was found that the dynamic storage moduli (G′ were higher than the loss moduli (G″ over the whole frequency range for all the groups. The SEM results showed that fibrinogen/knob-g-HA hydrogels presented the heterogeneous mesh-like structures which were different from the honeycomb-like structures of fibrinogen/MA-HA hydrogels. Correspondingly, a higher swelling ratio was obtained in the groups of fibrinogen/knob-g-HA hydrogel. Finally, the cytocompatibility of fibrinogen/knob-g-HA hydrogels was proved by live/dead stainings and MTT assays in the 293T cells encapsulation test. All these results highlight the biological potential of the fibrinogen/knob-g-HA hydrogels for 3D cellular engineering.

  2. Biocompatibility of hyaluronic acid hydrogels prepared by porous hyaluronic acid microbeads

    Science.gov (United States)

    Kim, Jin-Tae; Lee, Deuk Yong; Kim, Tae-Hyung; Song, Yo-Seung; Cho, Nam-Ihn

    2014-05-01

    Hyaluronic acid hydrogels (HAHs) were synthesized by immersing HA microbeads crosslinked with divinyl sulfone in a phosphate buffered saline solution to evaluate the biocompatibility of the gels by means of cytotoxicity, genotoxicity ( in vitro chromosome aberration test, reverse mutation assay, and in vivo micronucleus test), skin sensitization, and intradermal reactivity. The HAHs induced no cytotoxicity or genotoxicity. In guinea pigs treated with grafts and prostheses, no animals died and there were no abnormal clinical signs. The sensitization scores were zero in all guinea pigs after 24 h and 48 h challenge, suggesting that the HAHs had no contact allergic sensitization in the guinea pig maximization test. No abnormal signs were found in New Zealand White rabbits during the 72 h observation period after the injection. There was no difference between the HAHs and negative control mean scores because skin reaction such as erythema or oedema was not observed after injection. Experimental results suggest that the HAHs would be suitable for soft tissue augmentation due to the absence of cytotoxicity, genotoxicity, skin sensitization, and intradermal reactivity.

  3. Physicochemical and Antibacterial Properties of Carrageenan and Gelatine Hydrosols and Hydrogels Incorporated with Acidic Electrolyzed Water

    Directory of Open Access Journals (Sweden)

    Ewa Brychcy

    2015-12-01

    Full Text Available The article focuses on investigation of the effects of usage of acidic electrolyzed water (AEW with different sodium chloride concentration (0.001%, 0.01%, and 0.1% for the preparation of carrageenan and gelatine hydrosols and hydrogels. To determine physiochemical properties of hydrosols, the pH, oxidation-reduction potential (ORP, available chloride concentration (ACC and rheological parameters such us gelation and flow temperatures were measured. The samples were also characterized using Fourier transform infrared spectroscopy (FT IR and texture profile analysis (TPA. Additionally, the article contains an analysis of antibacterial activity of carrageenan and gelatine hydrosols incorporated with acidic electrolyzed water, against Staphylococcus aureus and Escherichia coli. The FT IR spectra demonstrated that the structure of gelatine and carrageenan are not significantly affected by electrolyzed NaCl solution components. Furthermore, TPA analysis showed that the use of AEW did not cause undesirable changes in hydrogels layer. The microbiological analysis confirmed inhibition of bacterial growth by hydrosols to about 2.10 log reduction. The results showed that the range of reduction of microorganisms depends on the type AEW used. This might be explained by the fact that the lowest pH and the highest ACC values of hydrosols were obtained for samples with the longest period of exposure to electrolysis (10 min and the highest amount of NaCl (0.1% w/v. These results suggest that hydrogels and hydrosols incorporated with AEW may be used for food preservation.

  4. Degradation Behaviour of Gamma Irradiated Poly(Acrylic Acid)-graft-Chitosan Superabsorbent Hydrogel

    Science.gov (United States)

    Ria Barleany, Dhena; Ilhami, Alpin; Yusuf Yudanto, Dea; Erizal

    2018-03-01

    A series of superabsorbent hydrogels were prepared from chitosan and partially neutralized acrylic acid at room temperature by gamma irradiation technique. The effect of irradiation and chitosan addition to the degradation behaviour of polymer were investigated. The gel content, swelling capacity, Equillibrium Degree of Swelling (EDS), Fourier Transform Infra Red (FTIR), and Scanning Electron Microscopy (SEM) study were also performed. Natural degradation in soil and thermal degradation by using of TGA analysis were observed. The variation of chitosan compositions were 0.5, 1, 1.5, and 2 g and the total irradiation doses were 5, 10, 15, and 20 kGy. The highest water capacity of 583.3 g water/g dry hydrogel was resulted from 5 kGy total irradiation dose and 0,5 g addition of chitosan. From the thermal degradation evaluation by using of TGA analysis showed that irradiation dose did not give a significant influence to the degradation rate. The rate of thermal degradation was ranged between 2.42 to 2.55 mg/min. In the natural test of degradation behaviour by using of soil medium, the hydrogel product with chitosan addition was found to have better degradability compared with the poly(acrylic acid) polymer without chitosan.

  5. Effect of citric acid crosslinking cellulose-based hydrogels on osteogenic differentiation.

    Science.gov (United States)

    Raucci, M G; Alvarez-Perez, M A; Demitri, C; Giugliano, D; De Benedictis, V; Sannino, A; Ambrosio, L

    2015-06-01

    Understanding the relationships between material surface properties and cellular responses is essential to designing optimal material surfaces for implantation and tissue engineering. In this study, cellulose hydrogels were crosslinked using a non-toxic and natural component namely citric acid. The chemical treatment induces COOH functional groups that improve the hydrophilicity, roughness, and materials rheological properties. The physiochemical, morphological, and mechanical analyses were performed to analyze the material surface before and after crosslinking. This approach would help determine if the effect of chemical treatment on cellulose hydrogel improves the hydrophilicity, roughness, and rheological properties of the scaffold. In this study, it was demonstrated that the biological responses of human mesenchymal stem cell with regard to cell adhesion, proliferation, and differentiation were influenced in vitro by changing the surface chemistry and roughness. © 2014 Wiley Periodicals, Inc.

  6. Structure and properties of semi-interpenetrating network hydrogel based on starch.

    Science.gov (United States)

    Zhu, Baodong; Ma, Dongzhuo; Wang, Jian; Zhang, Shuang

    2015-11-20

    Starch-g-P(acrylic acid-co-acrylamide)/PVA semi-interpenetrating network (semi-IPN) hydrogels were prepared by aqueous solution polymerization method. Starch grafting copolymerization reaction, semi-IPN structure and crystal morphology were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The PVA in the form of partial crystallization distributing in the gel matrix uniformly were observed by Field emission scanning electron microscope (FESEM). The space network structure, finer microstructure and pore size in the interior of hydrogel were presented by biomicroscope. The results demonstrated that absorption ratio of water and salt generated different degree changes with the effect of PVA. In addition, the mechanical strength of hydrogel was improved. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Properties and in vitro drug release of hyaluronic acid-hydroxyethyl cellulose hydrogels for transdermal delivery of isoliquiritigenin.

    Science.gov (United States)

    Kong, Bong Ju; Kim, Ayoung; Park, Soo Nam

    2016-08-20

    In the present study, the properties of hydrogel systems based on hyaluronic acid (HA)-hydroxyethyl cellulose (HEC) were investigated for effective transdermal delivery of isoliquiritigenin (ILTG). Hydrogels were synthesized by chemical cross-linking, and network structures were characterised using scanning electron microscopy (SEM) and surface area analyser. Texture properties and swelling of HA-HEC hydrogels were found to be closely linked to cross-linker concentration and swelling medium. Water in HA-HEC hydrogels was found to exist mostly in the form of free water. The viscoelasticity and the network stabilization of the hydrogels were analysed via rheological studies. The release kinetics of the hydrogel followed Fickian diffusion mechanism. In an in vitro skin penetration study, the system substantially improved the delivery of ILTG into the skin. These results indicate that the hydrogel system composed of HA and HEC has potential as a transdermal delivery system, with cross-linking density and the swelling medium influencing the properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Dually cross-linked single network poly(acrylic acid) hydrogels with superior mechanical properties and water absorbency.

    Science.gov (United States)

    Zhong, Ming; Liu, Yi-Tao; Liu, Xiao-Ying; Shi, Fu-Kuan; Zhang, Li-Qin; Zhu, Mei-Fang; Xie, Xu-Ming

    2016-06-28

    Poly(acrylic acid) (PAA) hydrogels with superior mechanical properties, based on a single network structure with dual cross-linking, are prepared by one-pot free radical polymerization. The network structure of the PAA hydrogels is composed of dual cross-linking: a dynamic and reversible ionic cross-linking among the PAA chains enabled by Fe(3+) ions, and a sparse covalent cross-linking enabled by a covalent cross-linker (Bis). Under deformation, the covalently cross-linked PAA chains remain intact to maintain their original configuration, while the Fe(3+)-enabled ionic cross-linking among the PAA chains is broken to dissipate energy and then recombined. It is found that the mechanical properties of the PAA hydrogels are significantly influenced by the contents of covalent cross-linkers, Fe(3+) ions and water, which can be adjusted within a substantial range and thus broaden the applications of the hydrogels. Meanwhile, the PAA hydrogels have excellent recoverability based on the dynamic and reversible ionic cross-linking enabled by Fe(3+) ions. Moreover, the swelling capacity of the PAA hydrogels is as high as 1800 times in deionized water due to the synergistic effects of ionic and covalent cross-linkings. The combination of balanced mechanical properties, efficient recoverability, high swelling capacity and facile preparation provides a new method to obtain high-performance hydrogels.

  9. Polyol and Amino Acid-Based Biosurfactants, Builders, and Hydrogels

    Science.gov (United States)

    This chapter reviews different detergent materials which have been synthesized from natural agricultural commodities. Background information, which gives reasons why the use of biobased materials may be advantageous, is presented. Detergent builders from L-aspartic acid, citric acid and D-sorbitol...

  10. Synthesis and Characterization of Superabsorbent Sodium Alginate-G-Poly (Potassium Acrylate Hydrogels Prepared By Using Gamma Irradiation

    Directory of Open Access Journals (Sweden)

    Erizal Erizal

    2017-07-01

    Full Text Available The aim of this research was to use gamma rays as sources for the preparation of superabsorbent hydrogels through radiation induced copolymerization. A series of superabsorbent hydrogels were prepared from aqueous solution containing partially neutralized acrylic acid (15% with different sodium alginate (NaAlg concentrations (0.5% to 1.5% by ionizing gamma irradiation (10 kGy to 40 kGy at room temperature. The effect of NaAlg concentration and irradiation doses on the water absorption behavior of the obtained hydrogels was investigated. The structural changes of hydrogels were characterized using Fourier Transform Infrared (FTIR whereas the morphologies of hydrogels were examined using Scanning Electron Microscope (SEM. The results showed the swelling of hydrogel in water and NaCl solution increases with increasing NaAlg concentration and decreases with increasing irradiation dose up to 40 kGy. The extend of gel fraction increases as a function of NaAlg concentration. The results of FTIR analysis revealed that acrylic acid and sodium alginate had been successfully grafted, while SEM examination showed that the hydrogels demonstrated large numbers of pores.     

  11. Peritoneal adhesion prevention with a biodegradable and injectable N,O-carboxymethyl chitosan-aldehyde hyaluronic acid hydrogel in a rat repeated-injury model

    Science.gov (United States)

    Song, Linjiang; Li, Ling; He, Tao; Wang, Ning; Yang, Suleixin; Yang, Xi; Zeng, Yan; Zhang, Wenli; Yang, Li; Wu, Qinjie; Gong, Changyang

    2016-11-01

    Postoperative peritoneal adhesion is one of the serious issues because it induces severe clinical disorders. In this study, we prepared biodegradable and injectable hydrogel composed of N,O-carboxymethyl chitosan (NOCC) and aldehyde hyaluronic acid (AHA), and assessed its anti-adhesion effect in a rigorous and severe recurrent adhesion model which is closer to clinical conditions. The flexible hydrogel, which gelated in 66 seconds at 37 °C, was cross-linked by the schiff base derived from the amino groups of NOCC and aldehyde groups in AHA. In vitro cytotoxicity test showed the hydrogel was non-toxic. In vitro and in vivo degradation examinations demonstrated the biodegradable and biocompatibility properties of the hydrogel. The hydrogel discs could prevent the invasion of fibroblasts, whereas fibroblasts encapsulated in the porous 3-dimensional hydrogels could grow and proliferate well. Furthermore, the hydrogel was applied to evaluate the anti-adhesion efficacy in a more rigorous recurrent adhesion model. Compared with normal saline group and commercial hyaluronic acid (HA) hydrogel, the NOCC-AHA hydrogel exhibited significant reduction of peritoneal adhesion. Compared to control group, the blood and abdominal lavage level of tPA was increased in NOCC-AHA hydrogel group. These findings suggested that NOCC-AHA hydrogel had a great potential to serve as an anti-adhesion candidate.

  12. A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

    Science.gov (United States)

    Sheikh, N.; Jalili, L.; Anvari, F.

    2010-06-01

    Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).

  13. A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

    International Nuclear Information System (INIS)

    Sheikh, N.; Jalili, L.; Anvari, F.

    2010-01-01

    Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).

  14. Preparation of poly(polyethylene glycol methacrylate-co-acrylic acid) hydrogels by radiation and their physical properties

    International Nuclear Information System (INIS)

    Park, S.-E.; Nho, Y.-C.; Kim, H.-I.

    2004-01-01

    The pH-responsive copolymer hydrogels were prepared with the monomers of polyethylene glycol methacrylate and acrylic acid based on γ-ray irradiation technique. The gel content of these copolymer hydrogels varied depending on both the composition of monomers and the radiation dose. Maximum gel percent and degree of crosslinking were obtained at the composition of equal amount of comonomers. These copolymer hydrogels did not show any noticeable change in swelling at lower pH range. However they showed an abrupt increase in swelling at higher pH range due to the ionization of carboxyl groups. This pH-responsive swelling behavior was applied for the insulin carrier via oral delivery. Insulin-loaded copolymer hydrogels released most of their insulin in the simulated intestinal fluid which had a pH of 6.8 but not in the simulated gastric fluid which had a pH of 1.2

  15. Hyaluronic acid hydrogels with IKVAV peptides for tissue repair and axonal regeneration in an injured rat brain

    International Nuclear Information System (INIS)

    Wei, Y T; Tian, W M; Yu, X; Cui, F Z; Hou, S P; Xu, Q Y; Lee, In-Seop

    2007-01-01

    A biocompatible hydrogel of hyaluronic acid with the neurite-promoting peptide sequence of IKVAV was synthesized. The characterization of the hydrogel shows an open porous structure and a large surface area available for cell interaction. Its ability to promote tissue repair and axonal regeneration in the lesioned rat cerebrum is also evaluated. After implantation, the polymer hydrogel repaired the tissue defect and formed a permissive interface with the host tissue. Axonal growth occurred within the microstructure of the network. Within 6 weeks the polymer implant was invaded by host-derived tissue, glial cells, blood vessels and axons. Such a hydrogel matrix showed the properties of neuron conduction. It has the potential to repair tissue defects in the central nervous system by promoting the formation of a tissue matrix and axonal growth by replacing the lost tissue

  16. Mechanical properties of poly(N-isopropylacrylamide-Co-itaconic acid) hydrogels

    International Nuclear Information System (INIS)

    Valderruten, N. E.; Quintana, J. R.; Katime, I.

    2001-01-01

    It is well known that polymers of N-isopropylacrylamide (NIPA) show lower critical solution temperature (LCST) behavior in water and its gels have a volume phase transition at about 34 degree centigree in water. In this study, we reported the polymerization of NIPA in the presence of N,N methylenebisacrylamide (BIS). Poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-itaconic acid) hydrogels were obtained by swelling the resultant solid xerogels to equilibrium in water. The effects of monomer composition and concentration of added cross-linking agent on the swelling behavior and mechanical properties of these hydrogels at 22 and 37 degree centigree were investigated, the latter involving measurements of shear in a DMTA system. The storage moduli at 22 degree centigree lay within the range 9.08-5.08 KPa. At a fixed BIS concentration, an increase from 22 to 37 degree centigree resulted in an increase in the shear moduli and the effective crosslinking density (v e ) and a decrease in the interaction parameter hydrogel/water, χ. (Author) 6 refs

  17. Hyaluronic Acid (HA)-Polyethylene glycol (PEG) as injectable hydrogel for intervertebral disc degeneration patients therapy

    Science.gov (United States)

    Putri Kwarta, Cityta; Widiyanti, Prihartini; Siswanto

    2017-05-01

    Chronic Low Back Pain (CLBP) is one health problem that is often encountered in a community. Inject-able hydrogels are the newest way to restore the disc thickness and hydration caused by disc degeneration by means of minimally invasive surgery. Thus, polymers can be combined to improve the characteristic properties of inject-able hydrogels, leading to use of Hyaluronic Acid (a natural polymer) and Polyethylene glycol (PEG) with Horse Radish Peroxide (HRP) cross linker enzymes. The swelling test results, which approaches were the ideal disc values, were sampled with variation of enzyme concentrations of 0.25 µmol/min/mL. The enzyme concentrations were 33.95%. The degradation test proved that the sample degradation increased along with the decrease of the HRP enzyme concentration. The results of the cytotoxicity assay with MTT assay method showed that all samples resulted in the 90% of living cells are not toxic. In vitro injection, models demonstrated that higher concentration of the enzymes was less state of gel which would rupture when released from the agarose gel. The functional group characterization shows the cross linking bonding in sample with enzyme adding. The conclusion of this study is PEG-HA-HRP enzyme are safe polymer composites which have a potential to be applied as an injectable hydrogel for intervertebral disc degeneration.

  18. Adsorption of {alpha}-amylase onto poly(N-vinyl 2-pyrrolidone/itaconic acid) hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Tuemtuerk, Hayrettin; Caykara, Tuncer; Kantoglu, Oemer; Gueven, Olgun

    1999-05-02

    {alpha}-Amylase enzyme was adsorbed on poly(N-vinyl 2-pyrrolidone/itaconic acid) (P(VP/IA)) hydrogels prepared by irradiating the ternary mixtures of VP/IA/water by {gamma}-rays at ambient temperature. The adsorption capacity of the hydrogels was determined to increase from 2.30 to 3.40 mg {alpha}-amylase/g dry gel with increasing amount of IA in gel system. Kinetic parameters were calculated as 2.51 g/dm{sup 3} for K{sub m} and 1.67x10{sup -3} g/dm{sup 3} min for V{sub max} for free enzyme and in the range of 3.88-5.02 g/dm{sup 3} for K{sub m} and 1.62x10{sup -3}-2.27 x 10{sup -3} g/dm{sup 3} min for V{sub max} depending on the amount of IA in the hydrogel. Enzyme activities were found to increase from 49.9% to 77.4% with increasing amount of IA in the gel system and retained their activities for one month storage. On the other hand, the free enzyme loses its activity completely after 20 days.

  19. Cupula-Inspired Hyaluronic Acid-Based Hydrogel Encapsulation to Form Biomimetic MEMS Flow Sensors.

    Science.gov (United States)

    Kottapalli, Ajay Giri Prakash; Bora, Meghali; Kanhere, Elgar; Asadnia, Mohsen; Miao, Jianmin; Triantafyllou, Michael S

    2017-07-28

    Blind cavefishes are known to detect objects through hydrodynamic vision enabled by arrays of biological flow sensors called neuromasts. This work demonstrates the development of a MEMS artificial neuromast sensor that features a 3D polymer hair cell that extends into the ambient flow. The hair cell is monolithically fabricated at the center of a 2 μm thick silicon membrane that is photo-patterned with a full-bridge bias circuit. Ambient flow variations exert a drag force on the hair cell, which causes a displacement of the sensing membrane. This in turn leads to the resistance imbalance in the bridge circuit generating a voltage output. Inspired by the biological neuromast, a biomimetic synthetic hydrogel cupula is incorporated on the hair cell. The morphology, swelling behavior, porosity and mechanical properties of the hyaluronic acid hydrogel are characterized through rheology and nanoindentation techniques. The sensitivity enhancement in the sensor output due to the material and mechanical contributions of the micro-porous hydrogel cupula is investigated through experiments.

  20. Comparison of Polymer Networks Synthesized by Conventional Free Radical and RAFT Copolymerization Processes in Supercritical Carbon Dioxide

    OpenAIRE

    Patricia Pérez-Salinas; Gabriel Jaramillo-Soto; Alberto Rosas-Aburto; Humberto Vázquez-Torres; María Josefa Bernad-Bernad; Ángel Licea-Claverie; Eduardo Vivaldo-Lima

    2017-01-01

    There is a debate in the literature on whether or not polymer networks synthesized by reversible deactivation radical polymerization (RDRP) processes, such as reversible addition-fragmentation radical transfer (RAFT) copolymerization of vinyl/divinyl monomers, are less heterogeneous than those synthesized by conventional free radical copolymerization (FRP). In this contribution, the syntheses by FRP and RAFT of hydrogels based on 2-hydroxyethylene methacrylate (HEMA) and ethylene glycol dimet...

  1. Macroporous modified poly (vinyl alcohol) hydrogels with charged groups for tissue engineering: Preparation and in vitro evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Drozdova, Maria G., E-mail: drozdovamg@gmail.com [Polymers for Biology Laboratory, Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry of Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997 (Russian Federation); Zaytseva-Zotova, Daria S. [Polymers for Biology Laboratory, Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry of Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997 (Russian Federation); Akasov, Roman A. [Polymers for Biology Laboratory, Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry of Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997 (Russian Federation); Sechenov First Moscow State Medical University, Institute for Regenerative Medicine, Trubetskaya str., 8/2, Moscow 119048 (Russian Federation); Golunova, Anna S.; Artyukhov, Alexander A. [D. Mendeleyev University of Chemical Technology of Russia, Miusskaya Square 9, Moscow 125047 (Russian Federation); Udartseva, Olga O.; Andreeva, Elena R. [Institute of Biomedical Problems of Russian Academy of Sciences, Khoroshevskoe Shosse 76a, Moscow 123007 (Russian Federation); Lisovyy, Denis E.; Shtilman, Michael I. [D. Mendeleyev University of Chemical Technology of Russia, Miusskaya Square 9, Moscow 125047 (Russian Federation); Markvicheva, Elena A. [Polymers for Biology Laboratory, Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry of Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, Moscow 117997 (Russian Federation)

    2017-06-01

    Poly(vinyl alcohol) (PVA) hydrogels are widely employed for various biomedical applications, including tissue engineering, due to their biocompatibility, high water solubility, low protein adsorption, and chemical stability. However, non-charged surface of PVA-based hydrogels is not optimal for cell adhesion and spreading. Here, cross-linked macroporous hydrogels based on low molecular weight acrylated PVA (Acr-PVA) was synthesized by modification of the pendant alcohol groups on the PVA with glycidyl methacrylate (GMA). To enhance cell affinity, charged groups were introduced to the hydrogel composition. For this purpose, Acr-PVA was copolymerized with either negatively charged acrylic acid (AA) or positively charged 2-(diethylamino) ethyl methacrylate (DEAEMA) monomers. A surface charge of the obtained hydrogels was found to be in function of the co-monomer type and content. Confocal microscopy observations confirmed that adhesion and spreading of both mouse fibroblasts (L929) and human mesenchymal stem cells (hMSC) on the modified Acr-PVA-AA and Acr-PVA-DEAEMA hydrogels were better than those on the non-modified Acr-PVA hydrogel. The increase of DEAEMA monomer content from 5 to 15 mol% resulted in the enhancement of cell viability which was 1.5-fold higher for Acr-PVA-DEAEMA-15 hydrogel than that of the non-modified Acr-PVA hydrogel sample. - Highlights: • To enhance cell affinity, acrylated PVA hydrogel was modified with AA or DEAEMA monomers. • Cell adhesion and spreading were found to depend on the co-monomer type and content. • Proliferation of L929 fibroblasts and stem cells increased on the modified hydrogels.

  2. Macroporous modified poly (vinyl alcohol) hydrogels with charged groups for tissue engineering: Preparation and in vitro evaluation

    International Nuclear Information System (INIS)

    Drozdova, Maria G.; Zaytseva-Zotova, Daria S.; Akasov, Roman A.; Golunova, Anna S.; Artyukhov, Alexander A.; Udartseva, Olga O.; Andreeva, Elena R.; Lisovyy, Denis E.; Shtilman, Michael I.; Markvicheva, Elena A.

    2017-01-01

    Poly(vinyl alcohol) (PVA) hydrogels are widely employed for various biomedical applications, including tissue engineering, due to their biocompatibility, high water solubility, low protein adsorption, and chemical stability. However, non-charged surface of PVA-based hydrogels is not optimal for cell adhesion and spreading. Here, cross-linked macroporous hydrogels based on low molecular weight acrylated PVA (Acr-PVA) was synthesized by modification of the pendant alcohol groups on the PVA with glycidyl methacrylate (GMA). To enhance cell affinity, charged groups were introduced to the hydrogel composition. For this purpose, Acr-PVA was copolymerized with either negatively charged acrylic acid (AA) or positively charged 2-(diethylamino) ethyl methacrylate (DEAEMA) monomers. A surface charge of the obtained hydrogels was found to be in function of the co-monomer type and content. Confocal microscopy observations confirmed that adhesion and spreading of both mouse fibroblasts (L929) and human mesenchymal stem cells (hMSC) on the modified Acr-PVA-AA and Acr-PVA-DEAEMA hydrogels were better than those on the non-modified Acr-PVA hydrogel. The increase of DEAEMA monomer content from 5 to 15 mol% resulted in the enhancement of cell viability which was 1.5-fold higher for Acr-PVA-DEAEMA-15 hydrogel than that of the non-modified Acr-PVA hydrogel sample. - Highlights: • To enhance cell affinity, acrylated PVA hydrogel was modified with AA or DEAEMA monomers. • Cell adhesion and spreading were found to depend on the co-monomer type and content. • Proliferation of L929 fibroblasts and stem cells increased on the modified hydrogels.

  3. [Thromboresistance of glucose-containing hydrogels].

    Science.gov (United States)

    Valuev, I L; Valuev, L I; Vanchugova, L V; Obydennova, I V; Valueva, T A

    2013-01-01

    The thromboresistance of glucose-sensitive polymer hydrogels, modeling one of the functions of the pancreas, namely, the ability to secrete insulin in response to the introduction of glucose into the environment, has been studied. Hydrogels were synthesized by the copolymerization of hydroxyethyl methacrylate with N-acryloyl glucosamine in the presence of a cross-linking agent and subsequently treated with concanavalin A. Introduction of glucose residues into the hydrogel did not result in significant changes in either the number of trombocytes adhered to the hydrogel or the degree of denaturation of blood plasma proteins interacting with the hydrogel. Consequently, the biological activity of insulin did not change after release from the hydrogel. The use of glucose-sensitive hydrogels is supposed to contribute to the development of a novel strategy for the treatment of diabetes.

  4. Carboxymethylcellulose hydrogel crosslinked with citric acid for biomedical application

    International Nuclear Information System (INIS)

    Capanema, Nadia S.V.; Mansur, Alexandra A.P.; Mansur, Herman S.; Universidade Federal de Minas Gerais

    2016-01-01

    The carboxymethylcellulose (CMCel) has been extensively used in order application as flexible polymer membrane. Biopolymers crosslinked have been studied to optimize their performance in biomedical applications. In this work, CMCel films with a degree of substitution (DS = 0.77) were prepared by evaporation of solvent and crosslinked with different concentrations of citric acid (CA). The synthesized CMCel was characterized by Infrared Spectroscopy by Fourier Transform X-ray spectroscopy (FTIR), and morphology assessed by scanning electron microscopy (SEM). Morphological analysis performed using the SEM indicated the crosslinked CMCel and not crosslinked with a very smooth and uniform appearance. The FTIR results indicated the modification of existing bands and appearance of a new band 1715 cm"-"1 suggesting that there has been change in the structure of the crosslinked CMCel. (author)

  5. Photocrosslinked alginate with hyaluronic acid hydrogels as vehicles for mesenchymal stem cell encapsulation and chondrogenesis.

    Science.gov (United States)

    Coates, Emily E; Riggin, Corinne N; Fisher, John P

    2013-07-01

    Ionic crosslinking of alginate via divalent cations allows for high viability of an encapsulated cell population, and is an effective biomaterial for supporting a spherical chondrocyte morphology. However, such crosslinking chemistry does not allow for injectable and stable hydrogels which are more appropriate for clinical applications. In this study, the addition of methacrylate groups to the alginate polymer chains was utilized so as to allow the free radical polymerization initiated by a photoinitiator during UV light exposure. This approach establishes covalent crosslinks between methacrylate groups instead of the ionic crosslinks formed by the calcium in unmodified alginate. Although this approach has been well described in the literature, there are currently no reports of stem cell differentiation and subsequent chondrocyte gene expression profiles in photocrosslinked alginate. In this study, we demonstrate the utility of photocrosslinked alginate hydrogels containing interpenetrating hyaluronic acid chains to support stem cell chondrogenesis. We report high cell viability and no statistical difference in metabolic activity between mesenchymal stem cells cultured in calcium crosslinked alginate and photocrosslinked alginate for up to 10 days of culture. Furthermore, chondrogenic gene markers are expressed throughout the study, and indicate robust differentiation up to the day 14 time point. At early time points, days 1 and 7, the addition of hyaluronic acid to the photocrosslinked scaffolds upregulates gene markers for both the chondrocyte and the superficial zone chondrocyte phenotype. Taken together, we show that photocrosslinked, injectable alginate shows significant potential as a delivery mechanism for cell-based cartilage repair therapies. Copyright © 2012 Wiley Periodicals, Inc.

  6. Rheology and adhesion of poly(acrylic acid)/laponite nanocomposite hydrogels as biocompatible adhesives.

    Science.gov (United States)

    Shen, Muxian; Li, Li; Sun, Yimin; Xu, Jun; Guo, Xuhong; Prud'homme, Robert K

    2014-02-18

    Biocompatible nanocomposite hydrogels (NC gels) consisting of poly(acrylic acid) (PAA) and nanosized clay (Laponite) were successfully synthesized by in situ free-radical polymerization of acrylic acid (AA) in aqueous solutions of Laponite. The obtained NC gels were uniform and transparent. Their viscosity, storage modulus G', and loss modulus G″ increased significantly upon increasing the content of Laponite and the dose of AA, while exhibiting a maximum with increasing the neutralization degree of AA. They showed tunable adhesion by changing the dose of Laponite and monomer as well as the neutralization degree of AA, as determined by 180° peel strength measurement. The maximal adhesion was shown when reaching a balance between cohesion and fluidity. A homemade Johnson-Kendall-Roberts (JKR) instrument was employed to study the surface adhesion behavior of the NC gels. The combination of peel strength, rheology, and JKR measurements offers the opportunity of insight into the mechanism of adhesion of hydrogels. The NC gels with tunable adhesion should be ideal candidates for dental adhesive, wound dressing, and tissue engineering.

  7. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels-Alder chemistry for adipose tissue engineering.

    Science.gov (United States)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

    2015-11-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels-Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37°C were studied. The results demonstrated that the aqueous Diels-Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. Copyright © 2015. Published by Elsevier B.V.

  8. Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

    International Nuclear Information System (INIS)

    Moon, Young-E; Jung, Gowun; Yun, Jumi; Kim, Hyung-Il

    2013-01-01

    Graphical abstract: The photocatalytic removal of pollutants was improved by the two-step mechanism based on the adsorption of pollutants by hydrogel and the effective decomposition by combination of TiO 2 and graphene oxide. -- Highlights: • pH sensitive PVA/PAAc hydrogels were prepared by radical polymerization and condensation reaction. • PVA/PAAc/TiO 2 /graphene oxide nanocomposite hydrogels were used for treatment of basic waste water. • Photocatalytic acitivity of TiO 2 was improved by incorporation of graphene oxide. • Photocatalytic decomposition by nanocomposite hydrogel was improved by increasing pH. -- Abstract: Poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 nanocomposite hydrogels. Both TiO 2 and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO 2 and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water

  9. Surface and anti-fouling properties of a polyampholyte hydrogel grafted onto a polyethersulfone membrane.

    Science.gov (United States)

    Zhang, Wei; Yang, Zhe; Kaufman, Yair; Bernstein, Roy

    2018-05-01

    Zwitterion polymers have anti-fouling properties; therefore, grafting new zwitterions to surfaces, particularly as hydrogels, is one of the leading research directions for preventing fouling. Specifically, polyampholytes, polymers of random mixed charged subunits with a net-electric charge, offer a synthetically easy alternative for studying new zwitterions with a broad spectrum of charged moieties. Here, a novel polyampholyte hydrogel was grafted onto the surface of polyethersulfone membrane by copolymerizing a mixture of vinylsulfonic acid (VSA) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METMAC) as the negatively and positively charged monomers, respectively, using various monomer ratios in the polymerization solution, and with N,N'-methylenebisacrylamide as the crosslinker. The physicochemical, morphological and anti-fouling properties of the modified membranes were systematically investigated. Hydrophilic hydrogels were successfully grafted using monomers at different molar ratios. A thin-film zwitterion hydrogel (∼90 nm) was achieved at a 3:1 [VSA:METMAC] molar ratio in the polymerization solution. Among all examined membranes, the zwitterion polyampholyte-modified membrane demonstrated the lowest adsorption of proteins, humic acid, and sodium alginate. It also had low fouling and high flux recovery following filtration with a protein or with an extracellular polymeric substance solution. These findings suggest that this polyampholyte hydrogel is applicable as a low fouling surface coating. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Preparation and Characteristics of Corn Straw-Co-AMPS-Co-AA Superabsorbent Hydrogel

    Directory of Open Access Journals (Sweden)

    Wei-Min Cheng

    2015-11-01

    Full Text Available In this study, the corn straw after removing the lignin was grafted with 2-acrylamido-2-methylpropanesulfonic acid (AMPS to prepare sulfonated cellulose. The grafting copolymerization between the sulfonated cellulose and acrylic acid (AA was performed using potassium persulfate and N,N′-methylenebisacrylamide as the initiator and crosslinking agent, respectively, to prepare corn straw-co-AMPS-co-AA hydrogels. The structure and properties of the resulting hydrogels were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and dynamic rheometry. The effects of initiator, crosslinker, monomer neutralization degree, and temperature on the swelling ratio of the hydrogels were studied. The water retention, salt resistance, and recyclability of the corn straw-co-AMPS-co-AA hydrogels were also investigated. The optimum water absorptivity of the corn straw hydrogels was obtained at a polymerization temperature of 50 °C with 1.2% crosslinker, 1:7 ratio of the pretreated corn straw and AA, 2% initiator, and 50% neutralized AA.

  11. Poly(AAc-co-MBA) hydrogel films: adhesive and mechanical properties in aqueous medium.

    Science.gov (United States)

    Arunbabu, Dhamodaran; Shahsavan, Hamed; Zhang, Wei; Zhao, Boxin

    2013-01-10

    Poly(acrylic acid-co-N,N'-methylenebisacrylamide) hydrogel films were synthesized by copolymerizing acrylic acid (AAc) with N,N'-methylenebisacrylamide (MBA) as a cross-linker via photo polymerization in the spacing confined between two glass plates. NMR spectroscopy was utilized to determine the cross-linking density. We found that the cross-linking density determined by NMR is higher than that expected from the feed concentrations of cross-linkers, suggesting that MBA is more reactive than AAc and the heterogeneous nature of the cross-linking. In addition to the swelling tests, indentation tests were performed on the hydrogel films under water to investigate effects of the cross-linking density on the adhesion and mechanical properties of the hydrogel films in terms of adhesive pull-off force and Hertz-type elastic modulus. As the cross-linker concentration increased, the effective elastic modulus of the hydrogel films increased dramatically at low cross-linking densities and reached a high steady-state value at higher cross-linking densities. The pull-off force decreased with increasing cross-linker concentration and reached a lower force plateau at high cross-linking densities. An optimal "trade-off" cross-linking density was determined to be 0.02 mol fraction of MBA in the hydrogel, where balanced elastic modulus and adhesive pull-off force can be obtained.

  12. Double printing of hyaluronic acid/poly(glycidol) hybrid hydrogels with poly(ϵ-caprolactone) for MSC chondrogenesis

    NARCIS (Netherlands)

    Stichler, Simone; Böck, Thomas; Paxton, Naomi; Bertlein, Sarah; Levato, Riccardo; Schill, Verena; Smolan, Willi; Malda, Jos; Teßmar, Jörg; Blunk, Torsten; Groll, Jürgen

    2017-01-01

    This study investigates the use of allyl-functionalized poly(glycidol)s (P(AGE-co-G)) as a cytocompatible cross-linker for thiol-functionalized hyaluronic acid (HA-SH) and the optimization of this hybrid hydrogel as bioink for 3D bioprinting. The chemical cross-linking of gels with 10 wt.% overall

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

    International Nuclear Information System (INIS)

    Nho, Y.C.; Mook Lim, Youn; Moo Lee, Young

    2004-01-01

    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 mmx3 mmx2.5 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

  14. Effect of ono and di-protic Acid on the Characterization of 2-hydroxyethyl-methacrylate based hydrogels Prepared by gamma-radiation and its Application for Delivery

    International Nuclear Information System (INIS)

    El-Arnaouty, M.B.

    2010-01-01

    New co polymeric hydrogels based on 2-hydroxyethyl methacrylate P(HEMA), 2-hydroxyethyl methacrylate/acrylic acid P(HEMA/AAc) and 2-hydroxyethyl methacrylate /maleic acid P(HEMA/MA) copolymers were prepared by using 60 Co gamma-rays, in order to examine the potential use of these hydrogels in controlled drug release systems. The characterization of network structure of these hydrogels was studied by FTIR, SEM and the gel fraction yield. The thermal stability by DSC and TGA, kinetic swelling, and drug release behavior were also studied. It was shown that as increasing irradiation dose, the gel fraction yield was increase and the swelling percent was decrease. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, swelling exponent (n), diffusion constant (K), diffusion coefficient (D) and penetration velocity (V) of the hydrogels were determined by studying the swelling behavior of the prepared hydrogels. Also, the swelling behavior of copolymer hydrogels in response to ph value of the external media was studied, it is noted that the highest swelling values were obtained at ph 6.8. The in vitro drug release behavior of these hydrogels was examined by quantification analysis using UV/VIS spectrophotometers. Colchicine is the drug which used in treatment of gout; it was loaded into dried hydrogels to investigate the stimuli-sensitive property at the specific ph. The release studies showed that the highest value of release was found to be at ph 6.8, such hydrogels could be used as drug delivery system

  15. Synthesis and characterization of poly(acrylic acid)-g-sodium alginate hydrogel initiated by gamma irradiation for controlled release of chlortetracycline HCl

    International Nuclear Information System (INIS)

    Mohamed, S.F.; Mahmoud, G.A.; Taleb, M.F.A.

    2013-01-01

    pH-Sensitive hydrogel was synthesized by gamma radiation crosslinking for sodium alginate extracted from the marine brown alga Turbinaria decurrens and acrylic acid. Preparation of the hydrogels involved free radical polymerization of a combination of acrylic acid (w = 0.2) and different contents of sodium alginate (w = 0.05, 0.10, and 0.15) in aqueous solution using gamma rays of a 60 Co source at an irradiation dose rate of 1.2 kGy/h. The swelling behavior of the prepared hydrogel was determined by investigating the swelling time, pH of medium, and alginate content in the hydrogel. The results showed that the hydrogel reached the equilibrium swelling state in water after 6 h. The hydrogel was found to be pH responsive. The drug loading and in vitro release properties of the hydrogel were also evaluated using chlortetracycline hydrochloride as the model drug. The adsorption isotherm studies by batching techniques under the effect of different initial feed concentrations of drug, different pH values, and different sodium alginate content of the adsorbent hydrogel were investigated. The diffusion of chlortetracycline hydrochloride within the hydrogel was found to be of non-Fickian character. The kinetic parameters such as the diffusion exponent, diffusion constant, and diffusion coefficient were also evaluated. (author)

  16. Enzyme-mediated hyaluronic acid-tyramine hydrogels for the propagation of human embryonic stem cells in 3D.

    Science.gov (United States)

    Xu, Keming; Narayanan, Karthikeyan; Lee, Fan; Bae, Ki Hyun; Gao, Shujun; Kurisawa, Motoichi

    2015-09-01

    The propagation of human embryonic stem cells (hESCs) in three-dimensional (3D) scaffolds facilitates the cell expansion process and supplies pluripotent cells of high quality for broad-spectrum applications in regenerative medicine. Herein, we report an enzyme-mediated hyaluronic acid-tyramine (HA-Tyr) hydrogel that encapsulated and propagated hESCs in 3D. HA-Tyr hydrogels were formed by crosslinking the tyramine moieties with horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). By changing the HRP and H2O2 concentration, we prepared HA-Tyr hydrogels of different mechanical strength and studied the self-renewal properties of hESCs in these scaffolds. We observed that both the chemical composition and mechanical strength of substrates were important factors affecting cell proliferation and pluripotency. The HA-Tyr hydrogel with a compressive modulus of ∼350Pa supported the proliferation of hESCs at the pluripotent state in both mTeSR1 medium and mouse embryonic fibroblast (MEF)-conditioned medium. Immunohistochemical analyses revealed that hESCs proliferated well and formed spheroid structures in 3D, without undergoing apoptosis. The hESCs cultured in HA-Tyr hydrogels showed high expression of CD44 and pluripotency markers. These cells exhibited the capability to form cell derivatives of all three embryonic germ layers in vitro and in vivo. In addition, the genetic integrity of the hESCs was unaffected in the 3D cultivation system. The scope of this study is to provide a stable 3D cultivation system for the expansion of human embryonic stem cells (hESCs) towards clinical applications. We report an enzyme mediated hyaluronic acid-tyramine (HA-Tyr) hydrogel that encapsulated and propagated hESCs in 3D. Unlike other HA-based photo-crosslinked hydrogel systems reported, we investigated the effects of mechanical strength of hydrogels on the self-renewal properties of hESCs in 3D. Then, we characterized hESCs cultured in hydrogels with lower mechanical strength

  17. Hyaluronic acid based hydrogel system for soft tissue regeneration and drug delivery

    Science.gov (United States)

    Jha, Amit Kumar

    We have developed hyaluronic acid (HA)-based, biomimetic hydrogel matrices that are hierarchically structured, mechanically robust and biologically active. Specifically, HA-based hydrogel particles (HGPs) with controlled sizes, defined porosity, and improved stability were synthesized using different inverse emulsion systems and crosslinking chemistries. The resultant particles either contained residual functional groups or were rendered reactive by subsequent chemical modifications. HA-based doubly crosslinked networks (DXNs) were synthesized via covalent crosslinking of HA HGPs with soluble HA macromers carrying mutually reactive functional groups. These hybrid matrices are hierarchical in nature, consisting of densely crosslinked HGPs integrated in a loosely connected secondary matrix. Their mechanical properties and degradation kinetics can be readily tuned by varying the particle size, functional group density, intra- and interparticle crosslinking. To improve the biological functions of HA HGPs, perlecan domain I (PlnDI), a basement membrane proteoglycan that has strong affinity for various heparin binding growth factors (HBGFs), was successfully conjugated to the particles through the core protein via a flexible poly(ethylene glycol) (PEG) linker. The immobilized PlnDI maintains its ability to bind bone morphogenetic proteins (BMP-2) and modulates its in vitro release. A similar, sustained release of BMP-2 was achieved by encapsulating BMP-2-loaded HGPs within a photocrosslinked HA matrix. When encapsulated in HA DXNs, primary bovine chondrocytes were able to maintain their phenotype, proliferate readily and produce abundant glycosaminoglycan. Finally, cell-adhesive HA DXNs were fabricated by encapsulating gelatin-decorated HA HGPs in a secondary HA matrix. Human MSCs were shown to adhere to the composite matrix through the focal adhesion sites clustered on particle surface. The cell-adhesive composite matrices supported hMSC proliferation and migration into

  18. Fibrous hyaluronic acid hydrogels that direct MSC chondrogenesis through mechanical and adhesive cues.

    Science.gov (United States)

    Kim, Iris L; Khetan, Sudhir; Baker, Brendon M; Chen, Christopher S; Burdick, Jason A

    2013-07-01

    Electrospinning has recently gained much interest due to its ability to form scaffolds that mimic the nanofibrous nature of the extracellular matrix, such as the size and depth-dependent alignment of collagen fibers within hyaline cartilage. While much progress has been made in developing bulk, isotropic hydrogels for tissue engineering and understanding how the microenvironment of such scaffolds affects cell response, these effects have not been extensively studied in a nanofibrous system. Here, we show that the mechanics (through intrafiber crosslink density) and adhesivity (through RGD density) of electrospun hyaluronic acid (HA) fibers significantly affect human mesenchymal stem cell (hMSC) interactions and gene expression. Specifically, hMSC spreading, proliferation, and focal adhesion formation were dependent on RGD density, but not on the range of fiber mechanics investigated. Moreover, traction-mediated fiber displacements generally increased with more adhesive fibers. The expression of chondrogenic markers, unlike trends in cell spreading and cytoskeletal organization, was influenced by both fiber mechanics and adhesivity, in which softer fibers and lower RGD densities generally enhanced chondrogenesis. This work not only reveals concurrent effects of mechanics and adhesivity in a fibrous context, but also highlights fibrous HA hydrogels as a promising scaffold for future cartilage repair strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Swelling, Mechanics, and Thermal/Chemical Stability of Hydrogels Containing Phenylboronic Acid Side Chains

    Directory of Open Access Journals (Sweden)

    Arum Kim

    2017-12-01

    Full Text Available We report here studies of swelling, mechanics, and thermal stability of hydrogels consisting of 20 mol % methacrylamidophenylboronic acid (MPBA and 80 mol % acrylamide (AAm, lightly crosslinked with methylenebisacrylamide (Bis. Swelling was measured in solutions of fixed ionic strength, but with varying pH values and fructose concentrations. Mechanics was studied by compression and hold. In the absence of sugar or in the presence of fructose, the modulus was mostly maintained during the hold period, while a significant stress relaxation was seen in the presence of glucose, consistent with reversible, dynamic crosslinks provided by glucose, but not fructose. Thermal stability was determined by incubating hydrogels at pH 7.4 at room temperature, and 37, 50, and 65 °C, and monitoring swelling. In PBS (phosphate buffered saline solutions containing 9 mM fructose, swelling remained essentially complete for 50 days at room temperature, but decreased substantially with time at the higher temperatures, with accelerated reduction of swelling with increasing temperature. Controls indicated that over long time periods, both the MPBA and AAm units were experiencing conversion to different species.

  20. Effect of cartilaginous matrix components on the chondrogenesis and hypertrophy of mesenchymal stem cells in hyaluronic acid hydrogels.

    Science.gov (United States)

    Zhu, Meiling; Feng, Qian; Sun, Yuxin; Li, Gang; Bian, Liming

    2017-11-01

    The microenvironment of the extracellular matrix (ECM) plays a key role in directing the viability and subsequent differentiation of the encapsulated stem cells by the specific integration between the hydrated biomolecules and cell surface receptors. Herein, we developed a hydrogel platform based on hyaluronic acid (HA) that presents cartilage ECM molecules as a form of developmental cues. The hybrid hydrogels were generated by coupling photo-cross-linkable methacrylated HA (MeHA) with selected cartilaginous ECM molecules including chondroitin sulfate (CS) and type I collagen (Col I), and we studied the decoupled function of these cues in regulating the initial chondrogenesis, subsequent hypertrophy, and tissue mineralization by hMSCs. The results indicate upregulated mRNA expression of the chondrogenesis markers in the HA hydrogels that contain Col I or CS, and decreased expression of the hypertrophic markers compared with the control MeHA group. The quantification results also show that glycosaminoglycans accumulation increases in the hybrid hydrogels containing cartilaginous ECM molecules, both in vitro and in vivo. We hypothesize that these additional ECM components in the HA hydrogels further regulate the hMSCs chondrogenesis and hypertrophy by coordination. The understanding obtained in this study may guide biomaterial scaffold design, thereby facilitating manipulation of the differentiation and mineralization of induced hMSCs for application in the repair of different musculoskeletal defects. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2292-2300, 2017. © 2016 Wiley Periodicals, Inc.

  1. The Effect of Chondroitin Sulphate and Hyaluronic Acid on Chondrocytes Cultured within a Fibrin-Alginate Hydrogel

    Directory of Open Access Journals (Sweden)

    Christopher J. Little

    2014-09-01

    Full Text Available Osteoarthritis is a painful degenerative joint disease that could be better managed if tissue engineers can develop methods to create long-term engineered articular cartilage tissue substitutes. Many of the tissue engineered cartilage constructs currently available lack the chemical stimuli and cell-friendly environment that promote the matrix accumulation and cell proliferation needed for use in joint cartilage repair. The goal of this research was to test the efficacy of using a fibrin-alginate hydrogel containing hyaluronic acid (HA and/or chondroitin sulphate (CS supplements for chondrocyte culture. Neonatal porcine chondrocytes cultured in fibrin-alginate hydrogels retained their phenotype better than chondrocytes cultured in monolayer, as evidenced by analysis of their relative expression of type II versus type I collagen mRNA transcripts. HA or CS supplementation of the hydrogels increased matrix glycosaminoglycan (GAG production during the first week of culture. However, the effects of these supplements on matrix accumulation were not additive and were no longer observed after two weeks of culture. Supplementation of the hydrogels with CS or a combination of both CS and HA increased the chondrocyte cell population after two weeks of culture. Statistical analysis indicated that the HA and CS treatment effects on chondrocyte numbers may be additive. This research suggests that supplementation with CS and/or HA has positive effects on cartilage matrix production and chondrocyte proliferation in three-dimensional (3D fibrin-alginate hydrogels.

  2. Alginate hydrogel as a potential alternative to hyaluronic acid as submucosal injection material.

    Science.gov (United States)

    Kang, Ki Joo; Min, Byung-Hoon; Lee, Jun Haeng; Kim, Eun Ran; Sung, Chang Ohk; Cho, Joo Young; Seo, Soo Won; Kim, Jae J

    2013-06-01

    Sodium alginate is currently used in medical products, including drugs and cosmetic materials. It can also be used as a submucosal injection material due to its excellent water retention ability. Alginate with a high water retention ability is called alginate hydrogel (AH). The aim of this study was to investigate the usefulness of AH as a submucosal injection material. To investigate the optimal viscosity of AH as a submucosal injection material, we observed the changes in submucosal height from the initial submucosal height in the stomachs of six miniature pigs for each injection material tested (0.3 % AH, 0.5 % hyaluronic acid, glycerol). All submucosal heights were compared serially over time (3, 5, 10, 20, and 30 min). Both immediate and 1-week delayed tissue reactions were investigated endoscopically in the same living pigs. Histological analyses were performed after the animals had been sacrificed. In a preliminary study, we determined that 0.3 % sodium alginate mixed with BaCl2 (400 μl) was the optimal viscosity of AH as an injection material. Our comparison of submucosal height changes over time showed that there was a significant decrease in submucosal height just 3 min following the injection of hyaluronic acid and glycerol, but that following the injection of AH a significant decrease in submucosal height was observed only after 10 min (p injection site. Alginate hydrogel demonstrated long-lasting maintenance of submucosal elevation, safety, and cost-effectiveness in a pig model, which makes it a potential alternative to hyaluronic acid.

  3. Elastin-like protein-hyaluronic acid (ELP-HA) hydrogels with decoupled mechanical and biochemical cues for cartilage regeneration.

    Science.gov (United States)

    Zhu, Danqing; Wang, Huiyuan; Trinh, Pavin; Heilshorn, Sarah C; Yang, Fan

    2017-05-01

    Hyaluronic acid (HA) is a major component of cartilage extracellular matrix and is an attractive material for use as 3D injectable matrices for cartilage regeneration. While previous studies have shown the promise of HA-based hydrogels to support cell-based cartilage formation, varying HA concentration generally led to simultaneous changes in both biochemical cues and stiffness. How cells respond to the change of biochemical content of HA remains largely unknown. Here we report an adaptable elastin-like protein-hyaluronic acid (ELP-HA) hydrogel platform using dynamic covalent chemistry, which allows variation of HA concentration without affecting matrix stiffness. ELP-HA hydrogels were created through dynamic hydrazone bonds via the reaction between hydrazine-modified ELP (ELP-HYD) and aldehyde-modified HA (HA-ALD). By tuning the stoichiometric ratio of aldehyde groups to hydrazine groups while maintaining ELP-HYD concentration constant, hydrogels with variable HA concentration (1.5%, 3%, or 5%) (w/v) were fabricated with comparable stiffness. To evaluate the effects of HA concentration on cell-based cartilage regeneration, chondrocytes were encapsulated within ELP-HA hydrogels with varying HA concentration. Increasing HA concentration led to a dose-dependent increase in cartilage-marker gene expression and enhanced sGAG deposition while minimizing undesirable fibrocartilage phenotype. The use of adaptable protein hydrogels formed via dynamic covalent chemistry may be broadly applicable as 3D scaffolds with decoupled niche properties to guide other desirable cell fates and tissue repair. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Synthesis and Swelling Behavior of pH-Sensitive Semi-IPN Superabsorbent Hydrogels Based on Poly(acrylic acid Reinforced with Cellulose Nanocrystals

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    Lim Sze Lim

    2017-11-01

    Full Text Available pH-sensitive poly(acrylic acid (PAA hydrogel reinforced with cellulose nanocrystals (CNC was prepared. Acrylic acid (AA was subjected to chemical cross-linking using the cross-linking agent MBA (N,N-methylenebisacrylamide with CNC entrapped in the PAA matrix. The quantity of CNC was varied between 0, 5, 10, 15, 20, and 25 wt %. X-ray diffraction (XRD data showed an increase in crystallinity with the addition of CNC, while rheology tests demonstrated a significant increase in the storage modulus of the hydrogel with an increase in CNC content. It was found that the hydrogel reached maximum swelling at pH 7. The potential of the resulting hydrogels to act as drug carriers was then evaluated by means of the drug encapsulation efficiency test using theophylline as a model drug. It was observed that 15% CNC/PAA hydrogel showed the potential to be used as drug carrier system.

  5. Diffusion coefficient, porosity measurement, dynamic and equilibrium swelling studies of Acrylic acid/Polyvinyl alcohol (AA/PVA hydrogels

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    Nazar Mohammad Ranjha

    2015-06-01

    Full Text Available Objective of the present work was to synthesize hydrogels of acrylic acid/polyvinyl alcohol (AA/PVA by free radical polymerization by using glutaradehyde (GA as crosslinkers. The hydrogels were evaluated for swelling, diffusion coefficient and network parameters like the average molecular weight between crosslink’s, polymer volume fraction in swollen state, number of repeating units between crosslinks and crosslinking density by using Flory-Huggins theory. It was found that the degree of swelling of AA/PVA hydrogels increases greatly within the pH range 5-7. The gel fraction and porosity increased by increasing the concentration of AA or PVA. Increase in degree of crosslinking, decreased the porosity and inverse was observed in gel fraction. Selected samples were loaded with metoprolol tartrate. Drug release was studied in USP hydrochloric acid solution of pH 1.2 and phosphate buffer solutions of pH 5.5 and 7.5. Various kinetics models like zero order, first order, Higuchi and Peppas model were used for in vitro kinetic studies. The results showed that the drug release followed concentration dependent effect (First order kinetics with non-Fickian diffusion. FTIR and SEM used to study the structure, crystallinity, compatibility, thermal stability and morphology of prepared and drug loaded hydrogels respectively.

  6. A RARE CASE OF AZEOTROPIC COPOLYMERIZATION

    NARCIS (Netherlands)

    JONGSMA, T; KIMKES, P; CHALLA, G

    1991-01-01

    Copolymerizations with both reactivity ratios equal to one are rare. Therefore, we report here on the radical copolymerization of styrene and p-tert-butoxy-carbonyl-oxy-styrene in toluene with AIBN as initiator. We found it to be an azeotropic copolymerization for all compositions, i.e. f1 = F1 and

  7. Synthesis of Potato Starch-Acrylic-Acid Hydrogels by Gamma Radiation and Their Application in Dye Adsorption

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    Md. Murshed Bhuyan

    2016-01-01

    Full Text Available Several kinds of acrylic-acid-grafted-starch (starch/AAc hydrogels were prepared at room temperature (27°C by applying 5, 10, 15, 20, and 25 kGy of gamma radiation to 15% AAc aqueous solutions containing 5, 7.5, and 15% of starch. With increment of the radiation dose, gel fraction became higher and attained the maximum (96.5% at 15 kGy, above which the fraction got lowered. On the other hand, the gel fraction monotonically increased with the starch content. Swelling ratios were lower for the starch/AAc hydrogels prepared with higher gamma-ray doses and so with larger starch contents. Significant promotions of the swelling ratios were demonstrated by hydrolysis with NaOH: 13632±10% for 15 kGy radiation-dosed [5% starch/15% AAc] hydrogel, while the maximum swelling ratio was ~200% for those without the treatment. The authors further investigated the availability of the starch/AAc hydrogel as an adsorbent recovering dye waste from the industrial effluents by adopting methylene blue as a model material; the hydrogels showed high dye-capturing coefficients which increase with the starch ratio. The optimum dye adsorption was found to be 576 mg per g of the hydrogel having 7.5 starch and 15% AAc composition. Two kinetic models, (i pseudo-first-order and (ii pseudo-second-order kinetic models, were applied to test the experimental data. The latter provided the best correlation of the experimental data compared to the pseudo-first-order model.

  8. Controlled Release of Indomethacin from Smart Starch-Based Hydrogels Prepared Acrylic Acid and b-Cyclodextrin as a Nanocarrier

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    Hossein Ghasemzadeh Mohammadi

    2017-01-01

    Full Text Available Controlled release of drugs can reduce the undesired effects of drug level fluctuations, and diminish the side effects as well as improve the therapeutic outcome of the drugs. In recent year, the scope of the drug delivery systems has been greatly expanded by the development of various hydrogels. The present work has focused on the design of a pH sensitive drug delivery system (DDS based on starch, acrylic acid (AA and β-cyclodextrins for controlled delivery of indomethacin. The hydrogels were prepared via graft polymerization of acrylic acid (AA onto starch and β-cyclodextrins backbones by a free radical polymerization technique. Cyclodextrins are able to form water-soluble complexes with many lipophilic water-insoluble drugs. In aqueous solutions, the drug molecules located in the central cavity of the cyclodextrin are in a dynamic equilibrium with free drug molecules. The interaction of drug with the polymer was evidenced by FTIR spectroscopy and thermal gravimetric analysis (TGA. The morphology of the samples was examined by scanning electron microscopy (SEM. The results showed that the hydrogels have good porosity and provided high surface area for the loading and release of drugs. Drug release behavior was carried out at physiological conditions of phosphate buffer, pH 8. In basic pH (like the intestine medium the hydrogels released the indomethacin, but in acidic pH (like the stomach medium there was no tendency to drug release. By increasing the amount of cyclodextrin, the rate of drug loading and release increased due to the dynamic equilibrium and interaction between the loaded drug and the cyclodextrin. This study has demonstrated that the hydrogel matrices are potentially suitable for controlled-release systems.

  9. Degradation of chitosan hydrogel dispersed in dilute carboxylic acids by solution plasma and evaluation of anticancer activity of degraded products

    Science.gov (United States)

    Chokradjaroen, Chayanaphat; Rujiravanit, Ratana; Theeramunkong, Sewan; Saito, Nagahiro

    2018-01-01

    Chitosan is a polysaccharide that has been extensively studied in the field of biomedicine, especially its water-soluble degraded products called chitooligosaccharides (COS). In this study, COS were produced by the degradation of chitosan hydrogel dispersed in a dilute solution (i.e., 1.55 mM) of various kinds of carboxylic acids using a non-thermal plasma technology called solution plasma (SP). The degradation rates of chitosan were influenced by the type of carboxylic acids, depending on the interaction between chitosan and each carboxylic acid. After SP treatment, the water-soluble degraded products containing COS could be easily separated from the water-insoluble residue of chitosan hydrogel by centrifugation. The production yields of the COS were mostly higher than 55%. Furthermore, the obtained COS products were evaluated for their inhibitory effect as well as their selectivity against human lung cancer cells (H460) and human lung normal cells (MRC-5).

  10. Photothermal-modulated drug delivery and magnetic relaxation based on collagen/poly(γ-glutamic acid hydrogel

    Directory of Open Access Journals (Sweden)

    Cho SH

    2017-03-01

    Full Text Available Sun-Hee Cho,1,* Ahreum Kim,1,* Woojung Shin,2 Min Beom Heo,1 Hyun Jong Noh,1 Kwan Soo Hong,3,4 Jee-Hyun Cho,3,4 Yong Taik Lim1,2 1SKKU Advanced Institute of Nanotechnology (SAINT, 2School of Chemical Engineering, Sungkyunkwan University, Suwon, 3Bioimaging Research Team, Korea Basic Science Institute, Cheongju, 4Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea *These authors contributed equally to this work Abstract: Injectable and stimuli-responsive hydrogels have attracted attention in molecular imaging and drug delivery because encapsulated diagnostic or therapeutic components in the hydrogel can be used to image or change the microenvironment of the injection site by controlling various stimuli such as enzymes, temperature, pH, and photonic energy. In this study, we developed a novel injectable and photoresponsive composite hydrogel composed of anticancer drugs, imaging contrast agents, bio-derived collagen, and multifaceted anionic polypeptide, poly (γ-glutamic acid (γ-PGA. By the introduction of γ-PGA, the intrinsic temperature-dependent phase transition behavior of collagen was modified to a low viscous sol state at room temperature and nonflowing gel state around body temperature. The modified temperature-dependent phase transition behavior of collagen/γ-PGA hydrogels was also evaluated after loading of near-infrared (NIR fluorophore, indocyanine green (ICG, which could transform absorbed NIR photonic energy into thermal energy. By taking advantage of the abundant carboxylate groups in γ-PGA, cationic-charged doxorubicin (Dox and hydrophobic MnFe2O4 magnetic nanoparticles were also incorporated successfully into the collagen/γ-PGA hydrogels. By illumination of NIR light on the collagen/γ-PGA/Dox/ICG/MnFe2O4 hydrogels, the release kinetics of Dox and magnetic relaxation of MnFe2O4 nanoparticles could be modulated. The experimental results suggest that

  11. Phospholipid Fatty Acids as Physiological Indicators of Paracoccus denitrificans Encapsulated in Silica Sol-Gel Hydrogels

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    Josef Trögl

    2015-02-01

    Full Text Available The phospholipid fatty acid (PLFA content was determined in samples of Paracoccus denitrificans encapsulated in silica hydrogel films prepared from prepolymerized tetramethoxysilane (TMOS. Immediately after encapsulation the total PLFA concentration was linearly proportional to the optical density (600 nm of the input microbial suspension (R2 = 0.99. After 7 days this relationship remained linear, but with significantly decreased slope, indicating a higher extinction of bacteria in suspensions of input concentration 108 cells/mL and higher. trans-Fatty acids, indicators of cytoplasmatic membrane disturbances, were below the detection limit. The cy/pre ratio (i.e., ratio of cyclopropylated fatty acids (cy17:0 + cy19:0 to their metabolic precursors (16:1ω7 + 18:1ω7, an indicator of the transition of the culture to a stationary growth-phase, decreased depending on co-immobilization of nutrients in the order phosphate buffer > mineral medium > Luria Broth rich medium. The ratio, too, was logarithmically proportional to cell concentration. These results confirm the applicability of total PLFA as an indicator for the determination of living biomass and cy/pre ratio for determination of nutrient limitation of microorganisms encapsulated in sol-gel matrices. This may be of interest for monitoring of sol-gel encapsulated bacteria proposed as optical recognition elements in biosensor construction, as well as other biotechnological applications.

  12. Acetic and Acrylic Acid Molecular Imprinted Model Silicone Hydrogel Materials for Ciprofloxacin-HCl Delivery

    Directory of Open Access Journals (Sweden)

    Lyndon Jones

    2012-01-01

    Full Text Available Contact lenses, as an alternative drug delivery vehicle for the eye compared to eye drops, are desirable due to potential advantages in dosing regimen, bioavailability and patient tolerance/compliance. The challenge has been to engineer and develop these materials to sustain drug delivery to the eye for a long period of time. In this study, model silicone hydrogel materials were created using a molecular imprinting strategy to deliver the antibiotic ciprofloxacin. Acetic and acrylic acid were used as the functional monomers, to interact with the ciprofloxacin template to efficiently create recognition cavities within the final polymerized material. Synthesized materials were loaded with 9.06 mM, 0.10 mM and 0.025 mM solutions of ciprofloxacin, and the release of ciprofloxacin into an artificial tear solution was monitored over time. The materials were shown to release for periods varying from 3 to 14 days, dependent on the loading solution, functional monomer concentration and functional monomer:template ratio, with materials with greater monomer:template ratio (8:1 and 16:1 imprinted tending to release for longer periods of time. Materials with a lower monomer:template ratio (4:1 imprinted tended to release comparatively greater amounts of ciprofloxacin into solution, but the release was somewhat shorter. The total amount of drug released from the imprinted materials was sufficient to reach levels relevant to inhibit the growth of common ocular isolates of bacteria. This work is one of the first to demonstrate the feasibility of molecular imprinting in model silicone hydrogel-type materials.

  13. Evaluation of Hydrogel Suppositories for Delivery of 5-Aminolevulinic Acid and Hematoporphyrin Monomethyl Ether to Rectal Tumors.

    Science.gov (United States)

    Ye, Xuying; Yin, Huijuan; Lu, Yu; Zhang, Haixia; Wang, Han

    2016-10-12

    We evaluated the potential utility of hydrogels for delivery of the photosensitizing agents 5-aminolevulinic acid (ALA) and hematoporphyrin monomethyl ether (HMME) to rectal tumors. Hydrogel suppositories containing ALA or HMME were administered to the rectal cavity of BALB/c mice bearing subcutaneous tumors of SW837 rectal carcinoma cells. For comparison, ALA and HMME were also administered by three common photosensitizer delivery routes; local administration to the skin and intratumoral or intravenous injection. The concentration of ALA-induced protoporphyrin IX or HMME in the rectal wall, skin, and subcutaneous tumor was measured by fluorescence spectrophotometry, and their distribution in vertical sections of the tumor was measured using a fluorescence spectroscopy system. The concentration of ALA-induced protoporphyrin IX in the rectal wall after local administration of suppositories to the rectal cavity was 9.76-fold (1 h) and 5.8-fold (3 h) higher than in the skin after cutaneous administration. The maximal depth of ALA penetration in the tumor was ~3-6 mm at 2 h after cutaneous administration. Much lower levels of HMME were observed in the rectal wall after administration as a hydrogel suppository, and the maximal depth of tumor penetration was <2 mm after cutaneous administration. These data show that ALA more readily penetrates the mucosal barrier than the skin. Administration of ALA as an intrarectal hydrogel suppository is thus a potential delivery route for photodynamic therapy of rectal cancer.

  14. Effect of Acid Hydrolysis and Thermal Hydrolysis on Solubility and Properties of Oil Palm Empty Fruit Bunch Fiber Cellulose Hydrogel

    Directory of Open Access Journals (Sweden)

    Sinyee Gan

    2015-11-01

    Full Text Available Cellulose hydrogel was produced from pretreated oil palm empty fruit bunch fiber (EFB that went through acid hydrolysis and thermal hydrolysis. The pretreated EFB was dissolved in LiOH/urea aqueous solution using the rapid dissolution method and was subjected to a crosslinking process with the aid of epichlorohydrin to form hydrogel. The effects of both hydrolyses’ time on average molecular weight (Mŋ, solubility, and properties of EFB hydrogels were evaluated. Both hydrolyses led to lower Mŋ, lower crystallinity index (CrI and hence, resulted in higher cellulose solubility. X-ray diffraction (XRD characterization revealed the CrI and transition of crystalline structure of EFB from cellulose I to II. The effects of hydrolysis time on the transparency, degree of swelling (DS, and morphology of the regenerated cellulose hydrogel were also investigated using an ultraviolet-visible (UV-Vis spectrophotometer and a Field emission scanning electron microscope (FESEM, respectively. These findings provide an efficient method to improve the solubility and properties of regenerated cellulose products.

  15. Controlled 5-fluorouracil release from hydrogels of Poly (acrylamide-co-metacrylic acid) crosslinked by means Of gamma irradiation techniques

    International Nuclear Information System (INIS)

    Rapado, M.; Sainz, D.; Altanes, S.; Prado, S.; Padron, S.; Salivar, D.; Chong, B.

    1999-01-01

    This report present the results on entrapped a cytostatic 5-Fluorouracil (5-F) in polymeric matrixes named hydrogels of polyacrylamide co -metacrylic acid crosslinked by means of gamma radiation with doses of 10,30, and 30 kGy at 25 o C. The drug delivery was followed by HPLC. The behavior of 5 -Fu migration from polymeric network was analyze by Iguchi equation for plain structure systems. The diffusion coefficients were obtained and drug release was in accordance with Fickian behavior

  16. Collagen and hyaluronic acid hydrogel in water-in-oil microemulsion delivery systems.

    Science.gov (United States)

    Kupper, Sylwia; Kłosowska-Chomiczewska, Ilona; Szumała, Patrycja

    2017-11-01

    The increase in skin related health issues has promoted interest in research on the efficacy of microemulsion in dermal and transdermal delivery of active ingredients. Here, we assessed the water-in-oil microemulsion capacity to incorporate two natural polymers, i.e. collagen and hyaluronic acid with low and high molecular weight. Systems were extensively characterized in terms of conductivity, phase inversion studies, droplet diameter, polydispersity index and rheological properties. The results of this research indicate that the structure and extent of water phase in microemulsions is governed by ratio and amount of surfactant mixture (sorbitan ester derivatives). However, results have also shown that collagen, depending upon the weight of the molecule and its surface activity, influence the droplet size of the microemulsions. While the hyaluronic acid, especially with high molecular weight, due to the water-binding ability and hydrogel formation alters the rheological properties of the microemulsion, thus providing viscous consistency of the formulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Local application of danazol-loaded hyaluronic acid hydrogel to endometriosis in a rat model.

    Science.gov (United States)

    Nomura, Kazuhito; Murakami, Koichi; Shozu, Makio; Nakama, Tsuyoshi; Yui, Nobuhiko; Inoue, Masaki

    2006-04-01

    To evaluate the efficacy of a drug delivery system composed of danazol-loaded hyaluronic acid for local application to endometriosis. Prospective, randomized study. Academic research unit of the department of obstetrics and gynecology in a university hospital. Adult female Sprague-Dawley rats. Danazol-loaded hyaluronic acid hydrogel (DZ-HA gel) was injected into the rat endometriosis model. Size and histological changes in experimental endometriosis, the concentration of danazol in the cyst wall and plasma, and estrous cycles were examined. Histologically, DZ-HA gel-treated cysts displayed marked atrophy of the endometrial epithelium. Increased numbers of apoptotic cells and decreased numbers of proliferative cells were noted with 10 mg/mL DZ-HA gel. Size of treated cysts decreased to approximately 60% at 9 weeks after injection. The estrous cycles were not disturbed during DZ-HA gel treatment. Local injection of DZ-HA gel achieved endometrial atrophy of an experimental model of endometriosis without disturbing the sexual cycle. These results suggest that local application of DZ using this drug delivery system may prove useful for treating endometriosis.

  18. Surface-functionalized polymethacrylic acid based hydrogel microparticles for oral drug delivery.

    Science.gov (United States)

    Sajeesh, S; Bouchemal, K; Sharma, C P; Vauthier, C

    2010-02-01

    Aim of the present work was to develop novel thiol-functionalized hydrogel microparticles based on poly(methacrylic acid)-chitosan-poly(ethylene glycol) (PCP) for oral drug delivery applications. PCP microparticles were prepared by a modified ionic gelation process in aqueous medium. Thiol modification of surface carboxylic acid groups of PCP micro particles was carried out by coupling l-cysteine with a water-soluble carbodiimide. Ellman's method was adopted to quantify the sulfhydryl groups, and dynamic light-scattering technique was used to measure the average particle size. Cytotoxicity of the modified particles was evaluated on Caco 2 cells by MTT assay. Effect of thiol modification on permeability of paracellular marker fluorescence dextran (FD4) was evaluated on Caco 2 cell monolayers and freshly excised rat intestinal tissue with an Ussing chamber set-up. Mucoadhesion experiments were carried out by an ex vivo bioadhesion method with excised rat intestinal tissue. The average size of the PCP microparticles was increased after thiol modification. Thiolated microparticles significantly improved the paracellular permeability of FD4 across Caco 2 cell monolayers, with no sign of toxicity. However, the efficacy of thiolated system remained low when permeation experiments were carried out across excised intestinal membrane. This was attributed to the high adhesion of the thiolated particles on the gut mucosa. Nevertheless, it can be concluded that surface thiolation is an interesting strategy to improve paracellular permeability of hydrophilic macromolecules. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  19. Structure- Property Behavior of Poly (acrylic acid) Hydrogels Synthesized by Radiation Induced Polymerization

    International Nuclear Information System (INIS)

    Nizam El-Din, H.M.M.; Ibrahim, M.S.

    2000-01-01

    Hydrogel containing hydroxyl group based on glycerol, ethylene glycol and acrylic monomer, have been prepared by using gamma radiation. The application of the prepared hydrogel for recovery of CU 2+ , Co 2+ , Ni 2+ , and Pb 2+ was also studied. The hydrogel for complexes with metals have been isolated and characterized by using different spectroscopic techniques IR and thermal analysis. TGA thermo grams were used to determine the kinetic parameters such as activation energy and order of reaction. The complexometric titration showed that the hydrogels have a great affinity to recover the metal ions in the following order Pb 2+ > Ni 2+ > Cu 2+ > Co 2+ . However the hydrogel containing glycerol has a great tendency towards metals recovery than than the one containing ethylene glycol

  20. Effect of Maleic Acid Content on the Thermal Stability, Swelling Behaviour and Network Structure of Gelatin -Based Hydrogels Prepared by Gamma Irradiation

    International Nuclear Information System (INIS)

    Eid, M.; Dessouki, A.M.; Abdel-Ghaffar, M.A.

    2005-01-01

    The preparation of highly swelling hydrogels containing diprotic acid and gelatin carried out by gamma-irradiation of acrylamide/maleic acid/gelatine/water mixture at ambient temperature. Poly (acrylamide/maleic acid/gelatin) p(AAm/MA/G) hydrogels were prepared in different MA and G contents at low dose rate (0.94 kGy/h), and moderate dose rate (3.84 kGy/h). The prepared hydrogels were confirmed by FT1R . The effect of copolymer composition, dose and dose rate on the swelling behaviour and the type of water diffusion in the network structure of the hydrogels was discussed. Increasing of MA content and G in the initial mixture leads to an increase in the amount of MA and G in the gel system and decrease in the gelation percent. The swelling behaviours of the hydrogel prepared at moderate dose rate increased with increasing MA mole content in the gel system. On the other hand, no systematic dependence of swelling on MA content was observed for the hydrogels obtained at low dose rate. Pore structure of the hydrogels was monitored by using scanning electron microscopy. Systematic swelling of P(AAm/MA/G) hydrogels prepared at moderate dose rates can be explained by the homogeneous pore size distribution of network. Thermogravimetric analysis (TGA) was employed to study the effect of network structure formation on the thermal behavior of the copolymer. To give a better understanding of the thermal stability of polymers, the rate of the thermal decomposition of P(AAm/MA/G) hydrogels has been evaluated

  1. Synthesis, characterization and properties of radiation-induced Starch/(EG-co-MAA hydrogels

    Directory of Open Access Journals (Sweden)

    H.L. Abd El-Mohdy

    2016-11-01

    Full Text Available Association of poly(carboxylic acids and non-ionic polymers in solutions via hydrogen bonding results in formation of novel polymeric materials–interpolymer complexes. Starch/(EG-co-MAA polymeric hydrogels were obtained by γ-initiated radiation copolymerization of ethylene glycol (EG with methacrylic acid (MAA which grafted on starch. The gel content of prepared hydrogels was varied with changes in starch content, EG:MAA composition and irradiation dose as well as crosslinking density. The swelling was studied as a function of starch content, EG:MAA composition, irradiation dose, type of soaked liquid, pH and temperature of matrix-surrounding medium. The degree of swelling greatly increased with enhanced MAA content, pH and temperature whereas, it decreased with reduced starch content and irradiation dose. The swelling was varied with the polarity of soaked liquid. The results showed that Starch/(EG-co-MAA hydrogels reached the equilibrium swelling state in water after 72 h. The structure and surface morphology of prepared polymer were confirmed with FTIR and SEM, respectively. The thermal properties of hydrogels were studied by using DSC and TGA, they cleared that there is miscibility between EG and MAA in copolymer and adding them improve the thermal stability of starch. The results indicate that Starch/(EG-co-MAA materials may be used in various applications.

  2. A polycarboxylic/amino functionalized hyaluronic acid derivative for the production of pH sensible hydrogels in the prevention of bacterial adhesion on biomedical surfaces.

    Science.gov (United States)

    Palumbo, Fabio Salvatore; Bavuso Volpe, Antonella; Cusimano, Maria Grazia; Pitarresi, Giovanna; Giammona, Gaetano; Schillaci, Domenico

    2015-01-15

    A graft copolymer derivative of hyaluronic acid bearing pendant amino and short polymethacrylate portions (HA-EDA-BMP-MANa) has been employed for the production of a pH sensible vancomycin releasing hydrogel and studied in vitro to test its potential anti adhesive property against Staphylococcus aureus colonization. The copolymer obtained through atom transfer radical polymerization bears chargeable (carboxyl and amino groups) portions and it could be formulated as a hydrogel at a concentration of 10%w/v. The HA-EDA-BMP-MANa hydrogels, produced at three different pH values (5, 6 and 7, respectively), were formulated with or without the addition of vancomycin (2%w/v). The vancomycin release profiles were detected and related to the starting hydrogel pH values, demonstrating that the systems were able to sustain the release of drug for more than 48 h. S. aureus adhesion tests were performed on glass culture plates and hydroxyapatite doped titanium surfaces, comparing the performances of HA-EDA-BMP-MANa hydrogel formulations (obtained with and without vancomycin) with similar formulations obtained using unmodified hyaluronic acid. The non fouling property of a selected HA-EDA-BMP-MANa hydrogel (without vancomycin) was also assayed with a BSA adsorption test. We found that the HA-EDA-BMP-MANa hydrogel even without vancomycin prevented bacterial adhesion on investigated surfaces. Copyright © 2014. Published by Elsevier B.V.

  3. Characterisation of Microbial Cellulose Modified by Graft Copolymerization Technique

    International Nuclear Information System (INIS)

    Tita Puspitasari; Cynthia Linaya Radiman

    2008-01-01

    Chemical and phisycal modifications of polymer can be carried out by radiation induced graft copolymerization. This research was carried out to study the morphology and crystallinity of microbial cellulose copolymer grafted by acrylic acid (MC-g-AAC). The SEM microstructural analysis proved that the acrylic acid could diffuse into the microbial celullose and resulted a dense structure. Crystallinity measurement showded that the crystalinity of microbial cellulose increase from 50 % to 53 % after modification. (author)

  4. Antibacterial Properties of Silver Nanoparticles Embedded on Polyelectrolyte Hydrogels Based on α-Amino Acid Residues

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    Mario Casolaro

    2018-05-01

    Full Text Available Polyelectrolyte hydrogels bearing l-phenylalanine (PHE, l-valine (AVA, and l-histidine (Hist residues were used as scaffolds for the formation of silver nanoparticles by reduction of Ag+ ions with NaBH4. The interaction with the metal ion allowed a prompt collapse of the swollen hydrogel, due to the neutralization reaction of basic groups present on the polymer. The imidazole nitrogen of the hydrogel with Hist demonstrated greater complexing capacity with the Ag+ ion compared to the hydrogels with carboxyl groups. The subsequent reduction to metallic silver allowed for the restoration of the hydrogel’s degree of swelling to the starting value. Transmission electron microscopy (TEM and spectroscopic analyses showed, respectively, a uniform distribution of the 15 nm spherical silver nanoparticles embedded on the hydrogel and peak optical properties around a wavelength of 400 nm due to the surface plasmonic effect. Unlike native hydrogels, the composite hydrogels containing silver nanoparticles showed good antibacterial activity as gram+/gram− bactericides, and higher antifungal activity against S. cerevisiae.

  5. Adsorption of ammonium and phosphate by feather protein based semi-interpenetrating polymer networks hydrogel as a controlled-release fertilizer.

    Science.gov (United States)

    Su, Yuan; Liu, Jia; Yue, Qinyan; Li, Qian; Gao, Baoyu

    2014-01-01

    A new feather protein-grafted poly(potassium acrylate)/polyvinyl alcohol (FP-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was produced through graft copolymerization with FP as a basic macromolecular skeletal material, acrylic acid as a monomer and PVA as a semi-IPNs polymer. The adsorption of ammonium and phosphate ions from aqueous solution using the new hydrogel as N and P controlled-release fertilizer with water-retention capacity was studied. The effects of pH value, concentration, contact time and ion strength on NH4+ and PO3-4 removal by FP-g-PKA/PVA semi-IPNs hydrogel were investigated using batch adsorption experiments. The results indicated that the hydrogel had high adsorption capacities and fast adsorption rates for NH4+ and PO3-4 in wide pH levels ranging from 4.0 to 9.0. Kinetic analysis presented that both NH4+ and PO3-4 removal were closely fitted with the pseudo-second-order model. Furthermore, the adsorption isotherms of hydrogel were best represented by the Freundlich model. The adsorption-desorption experimental results showed the sustainable stability of FP-g-PKA/PVA semi-IPNs hydrogel for NH4+ and PO3-4 removal. Overall, FP-g-PKA/PVA could be considered as an efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer.

  6. Poly-γ-Glutamic Acid Nanoparticles Based Visible Light-Curable Hydrogel for Biomedical Application

    Directory of Open Access Journals (Sweden)

    József Bakó

    2016-01-01

    Full Text Available Nanoparticles and hydrogels have gained notable attention as promising potential for fabrication of scaffolds and delivering materials. Visible light-curable systems can allow for the possibility of in situ fabrication and have the advantage of optimal applicability. In this study nanogel was created from methacrylated poly-gamma-glutamic acid nanoparticles by visible (dental blue light photopolymerization. The average size of the particles was 80 nm by DLS, and the NMR spectra showed that the methacrylation rate was 10%. Polymerization time was 3 minutes, and a stable nanogel with a swelling rate of 110% was formed. The mechanical parameters of the prepared structure (compression stress 0.73 MPa, and Young’s modulus 0.93 MPa can be as strong as necessary in a real situation, for example, in the mouth. A retaining effect of the nanogel was found for ampicillin, and the biocompatibility of this system was tested by Alamar Blue proliferation assay, while the cell morphology was examined by fluorescence and laser scanning confocal microscopy. In conclusion, the nanogel can be used for drug delivery, or it can be suitable for a control factor in different systems.

  7. Co-delivery of evodiamine and rutaecarpine in a microemulsion-based hyaluronic acid hydrogel for enhanced analgesic effects on mouse pain models.

    Science.gov (United States)

    Zhang, Yong-Tai; Li, Zhe; Zhang, Kai; Zhang, Hong-Yu; He, Ze-Hui; Xia, Qing; Zhao, Ji-Hui; Feng, Nian-Ping

    2017-08-07

    The aim of this study was to improve the analgesic effect of evodiamine and rutaecarpine, using a microemulsion-based hydrogel (ME-Gel) as the transdermal co-delivery vehicle, and to assess hyaluronic acid as a hydrogel matrix for microemulsion entrapment. A microemulsion was formulated with ethyl oleate as the oil core to improve the solubility of the alkaloids and was loaded into a hyaluronic acid-structured hydrogel. Permeation-enhancing effects of the microemulsion enabled evodiamine and rutaecarpine in ME-Gel to achieve 2.60- and 2.59-fold higher transdermal fluxes compared with hydrogel control (pmicroemulsion exhibited good skin biocompatibility, whereas effective ME-Gel co-delivery of evodiamine and rutaecarpine through the skin enhanced the analgesic effect in mouse pain models compared with hydrogel. Notably, evodiamine and rutaecarpine administered using ME-Gel effectively down-regulated serum levels of prostaglandin E 2 , interleukin 6, and tumor necrosis factor α in formaldehyde-induced mouse pain models, possibly reflecting the improved transdermal permeability of ME-Gel co-delivered evodiamine and rutaecarpine, particularly with hyaluronic acid as the hydrogel matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Optimization and translation of MSC-based hyaluronic acid hydrogels for cartilage repair

    Science.gov (United States)

    Erickson, Isaac E.

    2011-12-01

    Traumatic injury and disease disrupt the ability of cartilage to carry joint stresses and, without an innate regenerative response, often lead to degenerative changes towards the premature development of osteoarthritis. Surgical interventions have yet to restore long-term mechanical function. Towards this end, tissue engineering has been explored for the de novo formation of engineered cartilage as a biologic approach to cartilage repair. Research utilizing autologous chondrocytes has been promising, but clinical limitations in their yield have motivated research into the potential of mesenchymal stem cells (MSCs) as an alternative cell source. MSCs are multipotent cells that can differentiate towards a chondrocyte phenotype in a number of biomaterials, but no combination has successfully recapitulated the native mechanical function of healthy articular cartilage. The broad objective of this thesis was to establish an MSC-based tissue engineering approach worthy of clinical translation. Hydrogels are a common class of biomaterial used for cartilage tissue engineering and our initial work demonstrated the potential of a photo-polymerizable hyaluronic acid (HA) hydrogel to promote MSC chondrogenesis and improved construct maturation by optimizing macromer and MSC seeding density. The beneficial effects of dynamic compressive loading, high MSC density, and continuous mixing (orbital shaker) resulted in equilibrium modulus values over 1 MPa, well in range of native tissue. While compressive properties are crucial, clinical translation also demands that constructs stably integrate within a defect. We utilized a push-out testing modality to assess the in vitro integration of HA constructs within artificial cartilage defects. We established the necessity for in vitro pre-maturation of constructs before repair to achieve greater integration strength and compressive properties in situ. Combining high MSC density and gentle mixing resulted in integration strength over 500 k

  9. Synthesis, Characterization, and Acute Oral Toxicity Evaluation of pH-Sensitive Hydrogel Based on MPEG, Poly(ε-caprolactone, and Itaconic Acid

    Directory of Open Access Journals (Sweden)

    Liwei Tan

    2013-01-01

    Full Text Available A kind of chemically cross-linked pH-sensitive hydrogels based on methoxyl poly(ethylene glycol-poly(caprolactone-acryloyl chloride (MPEG-PCL-AC, PECA, poly(ethylene glycol methyl ether methacrylate (MPEGMA, MEG, N,N-methylenebisacrylamide (BIS, and itaconic acid (IA were prepared without using any organic solvent by heat-initiated free radical method. The obtained macromonomers and hydrogels were characterized by 1H NMR and FT-IR, respectively. Morphology study of hydrogels was also investigated in this paper, and it showed that the hydrogels had good pH-sensitivity. The acute toxicity test and histopathological study were conducted in BALB/c mice. The results indicated that the maximum tolerance dose of the hydrogel was higher than 10000 mg/kg body weight. No morality or signs of toxicity were observed during the whole 7-day observation period. Compared to the control groups, there were no important adverse effects in the variables of hematology routine test and serum chemistry analysis both in male or female treatment group. Histopathological study also did not show any significant lesions, including heart, liver, lung, spleen, kidney, stomach, intestine, and testis. All the results demonstrated that this hydrogel was nontoxic after gavage. Thus, the hydrogel might be the biocompatible potential candidate for oral drug delivery system.

  10. Effect of maleic acid content on the thermal stability, swelling behaviour and network structure of gelatin-based hydrogels prepared by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Eid, M. [National Center For Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo 11731 (Egypt)], E-mail: mona_eid2000@yahoo.com; Abdel-Ghaffar, M.A. [National Research Center, Dokki, Cairo (Egypt); Dessouki, A.M. [National Center For Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo 11731 (Egypt)

    2009-01-15

    The highly swelling Poly (acrylamide/maleic acid/gelatin) P(AAm/MA/G) hydrogels were prepared by gamma-irradiation at low dose rate (0.94 kGy/h) and moderate dose rate (3.84 kGy/h). The hydrogels were confirmed by FTIR. The effect of copolymer composition, dose and dose rate on the swelling behaviour was discussed. Increasing of MA content and G in the initial mixture leads to an increase in the amount of MA and G in the gel system and decrease in the gelation %. The swelling behaviours of the hydrogel prepared at moderate dose rate increased with increasing MA mole content in the gel system but, there is no systematic dependence of swelling on MA content was observed for the hydrogels obtained at low dose rate. Pore structure of the hydrogels was monitored by using scanning electron microscopy. Thermogravimetric analysis (TGA) and the rate of the thermal decomposition of P(AAm/MA/G) hydrogels has been evaluated to give a better understanding of the thermal stability of polymers, The X-ray data of P(AAm/MA/G) hydrogels was discussed to investigate some features namely the degree of ordering and crystallite size.

  11. Biodegradable and thermosensitive monomethoxy poly(ethylene glycol)-poly(lactic acid) hydrogel as a barrier for prevention of post-operative abdominal adhesion.

    Science.gov (United States)

    Fu, Shao Zhi; Li, Zhi; Fan, Jun Ming; Meng, Xiao Hang; Shi, Kun; Qu, Ying; Yang, Ling Lin; Wu, Jing Bo; Fan, Juan; Luot, Feng; Qian, Zhi Yong

    2014-03-01

    Post-operative peritoneal adhesions are serious consequences of abdominal or pelvic surgery and cause severe bowel obstruction, chronic pelvic pain and infertility. In this study, a novel nano-hydrogel system based on a monomethoxy poly(ethylene glycol)-poly(lactic acid) (MPEG-PLA) di-block copolymer was studied for its ability to prevent abdominal adhesion in rats. The MPEG-PLA hydrogel at a concentration of 40% (w/v) was injected and was able to adhere to defect sites at body temperature. The ability of the hydrogel to inhibit adhesion of post-operative tissues was evaluated by utilizing a rat model of abdominal sidewall-cecum abrasion. It was possible to heal wounded tissue through regeneration of neo-peritoneal tissues ten days after surgery. Our data showed that this hydrogel system is equally as effective as current commercialized anti-adhesive products.

  12. Dynamic behavior of acrylic acid clusters as quasi-mobile nodes in a model of hydrogel network

    Science.gov (United States)

    Zidek, Jan; Milchev, Andrey; Vilgis, Thomas A.

    2012-12-01

    Using a molecular dynamics simulation, we study the thermo-mechanical behavior of a model hydrogel subject to deformation and change in temperature. The model is found to describe qualitatively poly-lactide-glycolide hydrogels in which acrylic acid (AA)-groups are believed to play the role of quasi-mobile nodes in the formation of a network. From our extensive analysis of the structure, formation, and disintegration of the AA-groups, we are able to elucidate the relationship between structure and viscous-elastic behavior of the model hydrogel. Thus, in qualitative agreement with observations, we find a softening of the mechanical response at large deformations, which is enhanced by growing temperature. Several observables as the non-affinity parameter A and the network rearrangement parameter V indicate the existence of a (temperature-dependent) threshold degree of deformation beyond which the quasi-elastic response of the model system turns over into plastic (ductile) one. The critical stretching when the affinity of the deformation is lost can be clearly located in terms of A and V as well as by analysis of the energy density of the system. The observed stress-strain relationship matches that of known experimental systems.

  13. Autonomic composite hydrogels by reactive printing: materials and oscillatory response.

    Science.gov (United States)

    Kramb, R C; Buskohl, P R; Slone, C; Smith, M L; Vaia, R A

    2014-03-07

    Autonomic materials are those that automatically respond to a change in environmental conditions, such as temperature or chemical composition. While such materials hold incredible potential for a wide range of uses, their implementation is limited by the small number of fully-developed material systems. To broaden the number of available systems, we have developed a post-functionalization technique where a reactive Ru catalyst ink is printed onto a non-responsive polymer substrate. Using a succinimide-amine coupling reaction, patterns are printed onto co-polymer or biomacromolecular films containing primary amine functionality, such as polyacrylamide (PAAm) or poly-N-isopropyl acrylamide (PNIPAAm) copolymerized with poly-N-(3-Aminopropyl)methacrylamide (PAPMAAm). When the films are placed in the Belousov-Zhabotinsky (BZ) solution medium, the reaction takes place only inside the printed nodes. In comparison to alternative BZ systems, where Ru-containing monomers are copolymerized with base monomers, reactive printing provides facile tuning of a range of hydrogel compositions, as well as enabling the formation of mechanically robust composite monoliths. The autonomic response of the printed nodes is similar for all matrices in the BZ solution concentrations examined, where the period of oscillation decreases in response to increasing sodium bromate or nitric acid concentration. A temperature increase reduces the period of oscillations and temperature gradients are shown to function as pace-makers, dictating the direction of the autonomic response (chemical waves).

  14. Synthesis of nano-sized stereoselective imprinted polymer by copolymerization of (S)-2-(acrylamido) propanoic acid and ethylene glycol dimethacrylate in the presence of racemic propranolol and copper ion

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Taher, E-mail: talizadeh@ut.ac.ir [Department of Analytical Chemistry, Faculty of Chemistry, University College of Science, University of Tehran, P.O. Box 14155-6455, Tehran (Iran, Islamic Republic of); Bagherzadeh, Azam; Shamkhali, Amir Nasser [Department of Applied Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2016-06-01

    A new chiral functional monomer of (S)-2-(acrylamido) propanoic acid was obtained by reaction of (L)-alanine with acryloyl chloride. The resulting monomer was characterized by FT-IR and HNMR and then utilized for the preparation of chiral imprinted polymer (CIP). This was carried out by copolymerization of (L)-alanine-derived chiral monomer and ethylene glycol dimethacrylate, in the presence of racemic propranolol and copper nitrate, via precipitation polymerization technique, resulting in nano-sized networked polymer particles. The polymer obtained was characterized by scanning electron microscopy and FT-IR. The non-imprinted polymer was also synthesized and used as blank polymer. Density functional theory (DFT) was also employed to optimize the structures of two diasterometric ternary complexes, suspected to be created in the pre-polymerization step, by reaction of optically active isomers of propranolol, copper ion and (S)-2-(acrylamido) propanoic acid. Relative energies and other characteristics of the described complexes, calculated by the DFT, predicted the higher stability of (S)-propranolol involved complex, compared to (R)-propranolol participated complex. Practical batch extraction test which employed CIP as solid phase adsorbent, indicated that the CIP recognized selectively (S)-propranolol in the racemic mixture of propranolol; whereas, the non-imprinted polymer (NIP) showed no differentiation capability between two optically active isomers of propranolol. - Highlights: • A new chiral functional monomer of (S)-2-(acrylamido) propanoic acid was synthesized. • (S)-propranolol-selective imprinted polymer was synthesized using the chiral monomer. • Racemic propranolol mixed with Cu(II) was used as template in the imprinting. • Density functional theory was employed to clarify the imprinting mechanism. • (S)-propranolol-Cu(II) complex was shown to conduct the imprinting process.

  15. A Review of Hyaluronic Acid and Hyaluronic Acid-based Hydrogels for Vocal Fold Tissue Engineering.

    Science.gov (United States)

    Walimbe, Tanaya; Panitch, Alyssa; Sivasankar, Preeti M

    2017-07-01

    Vocal fold scarring is a common cause of dysphonia. Current treatments involving vocal fold augmentation do not yield satisfactory outcomes in the long term. Tissue engineering and regenerative medicine offer an attractive treatment option for vocal fold scarring, with the aim to restore the native extracellular matrix microenvironment and biomechanical properties of the vocal folds by inhibiting progression of scarring and thus leading to restoration of normal vocal function. Hyaluronic acid is a bioactive glycosaminoglycan responsible for maintaining optimum viscoelastic properties of the vocal folds and hence is widely targeted in tissue engineering applications. This review covers advances in hyaluronic acid-based vocal fold tissue engineering and regeneration strategies. Copyright © 2017. Published by Elsevier Inc.

  16. Preparation and characterization of acrylic acid-grafted poly (vinyl alcohol) hydrogel actuators using γ-ray irradiation

    International Nuclear Information System (INIS)

    An, Sung Jun; Lim, Youn Mook; Gwon, Hui Jeong; Kim, Yun Hye; Youn, Min Ho; Nho, Young Chang; Han, Dong Hyun; Kim, Chong Yeal

    2008-01-01

    Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as biomimetic actuators and artificial muscles. In this study, poly (vinyl alcohol)(PVA) grafted acrylic acid monomer (PVA-g-AAc) hydrogels were prepared by 60 Co γ-ray irradiation and their properties such as degree of grafting and weight swelling in electrostimulation as an artificial muscle and actuator were investigated

  17. Study of the contribution of the state of water to the gel properties of a photocrosslinked polyacrylic acid hydrogel using magnetic resonance imaging.

    Science.gov (United States)

    Onuki, Yoshinori; Hasegawa, Naoki; Kida, Chihiro; Obata, Yasuko; Takayama, Kozo

    2014-11-01

    Photocrosslinked polyacrylic acid (PAA-HEMA) hydrogels are a promising candidate for use in dermatological patch adhesives. To gain further knowledge about the properties of this gel, we investigated the T1 relaxation time and the diffusion coefficient (D) of water in the hydrogels using magnetic resonance (MR) imaging. Hydrogels with different formulations and process factors were prepared and tested. The observed data were analyzed by ANOVA, which clarified the mode of action of the formulation and process factors based on these MR parameters. Various gel properties (i.e., gel fraction, swelling capacity, gel strength, and water-retention ability) were also measured, followed by a Bayesian network (BN) analysis. The BN allowed us to summarize well the relationships between the formulation and process factors, MR parameters, and gel properties. T1 was associated with the swelling and water-retention properties of the hydrogel, whereas D was associated with gel formation and gel strength. Furthermore, this study clarified that T1 and D mostly represented the hydration and water-compartmentalization effects of the hydrogel, respectively. In conclusion, the state of water seems to play an important role in the properties of the PAA-HEMA hydrogel. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  18. Programmable release of multiple protein drugs from aptamer-functionalized hydrogels via nucleic acid hybridization.

    Science.gov (United States)

    Battig, Mark R; Soontornworajit, Boonchoy; Wang, Yong

    2012-08-01

    Polymeric delivery systems have been extensively studied to achieve localized and controlled release of protein drugs. However, it is still challenging to control the release of multiple protein drugs in distinct stages according to the progress of disease or treatment. This study successfully demonstrates that multiple protein drugs can be released from aptamer-functionalized hydrogels with adjustable release rates at predetermined time points using complementary sequences (CSs) as biomolecular triggers. Because both aptamer-protein interactions and aptamer-CS hybridization are sequence-specific, aptamer-functionalized hydrogels constitute a promising polymeric delivery system for the programmable release of multiple protein drugs to treat complex human diseases.

  19. Burkholderia sacchari DSM 17165: A source of compositionally-tunable block-copolymeric short-chain poly(hydroxyalkanoates) from xylose and levulinic acid

    Science.gov (United States)

    Burkholderia sacchari DSM 17165 was used as a biocatalyst for the production of poly-3-hydroxybutyrate-co-3-hydroxyvalerate block copolymers (Poly-3HB-block-3HV) from xylose and levulinic acid. Among the carbon source mixtures, levulinic acid was preferred and was consumed early in the fermentations...

  20. The evaluation of temperature and pH influences on equilibrium swelling of poly(n-isopropylacrylamide-co-acrylic acid hydrogels

    Directory of Open Access Journals (Sweden)

    Zdravković Aleksandar S.

    2017-01-01

    Full Text Available Hydrogels are synthesized by the method of radical polymerization of monomers: N-isopropylacrylamide (NIPAM and acrylic acid (AA. Characterization of poly(N-isopropylacrylamide- co-acrylic acid hydrogels, p(NIPAM/AA, has been performed by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD and by determination of the swelling behaviour in aqueous solutions at different temperatures (25, 31 and 37°C and pH values (2.2, 4.5, 6 and 6.8. After lyophilisation in the solution at pH 6 and temperature of 25°C, p(NIPAM/AA hydrogels have rapidly reached equilibrium degree of swelling, αe, in comparison to non-lyophilized samples. The mechanism of solvent transport within matrix in lyophilized samples corresponds to less Fickian diffusion, whereas Super case II diffusion is characteristic for non-lyophilized samples. p(NIPAM/AA hydrogel with 1.5 mol% of ethylene glycol dimethacrylate (EGDM at the temperature of 25°C and pH 6.8, has reached the highest swelling equilibrium degree, αe = 259.8. The results of swelling studies have shown that p(NIPAM/AA hydrogels can be classified as superabsorbent polymers (SAPs. For the evaluation of pH and temperature influences on synthesized hydrogels swelling, a full three-level experimental design has been used. Two-factor interaction model (2FI is the most optimal model of a full three-level experimental design for representing the swelling equilibrium degree of p(NIPAM/AA hydrogels as a function of investigated parameters, i.e., temperature and pH. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-34012

  1. 3D bioprinting of methacrylated hyaluronic acid (MeHA) hydrogel with intrinsic osteogenicity

    NARCIS (Netherlands)

    Poldervaart, Michelle T.; Goversen, Birgit; De Ruijter, Mylene; Abbadessa, Anna; Melchels, Ferry P.W.; Öner, F. Cumhur; Dhert, Wouter J A; Vermonden, Tina; Alblas, Jacqueline

    2017-01-01

    In bone regenerative medicine there is a need for suitable bone substitutes. Hydrogels have excellent biocompatible and biodegradable characteristics, but their visco-elastic properties limit their applicability, especially with respect to 3D bioprinting. In this study, we modified the naturally

  2. Burkholderia sacchari DSM 17165: A source of compositionally-tunable block-copolymeric short-chain poly(hydroxyalkanoates) from xylose and levulinic acid.

    Science.gov (United States)

    Ashby, Richard D; Solaiman, Daniel K Y; Nuñez, Alberto; Strahan, Gary D; Johnston, David B

    2018-04-01

    Burkholderia sacchari was used to produce poly-3-hydroxybutyrate-co-3-hydroxyvalerate block copolymers from xylose and levulinic acid. Levulinic acid was the preferred substrate resulting in 3-hydroxyvalerate (3HV) contents as high as 95 mol% at 24 h. The 3HB:3HV ratios were controlled by the initial levulinic acid media concentration and fermentation length. Higher levulinic acid concentrations and longer durations, resulted in polymers with two glass transition temperatures, each approximating those associated with poly-3HB and poly-3HV. 13 C NMR confirmed the presence of high concentrations of 3HB-3HB and 3HV-3HV homopolymeric dyads, while mass spectrometry of the partial hydrolysis products did not conform to Bernoullian statistics for randomness, confirming block sequences. MS/MS analysis of specific oligomers showed the mass-loss of 86 amu (a 3HB unit) and 100 amu (a 3HV unit) attesting to some randomness within the polymers. This study verifies the potential for producing Poly-3HB-block-3HV copolymers from inexpensive biorenewable feedstocks without sequential addition of carbon sources. Published by Elsevier Ltd.

  3. Radiation-induced synthesis and swelling properties of p(2-hydroxyethyl methacrylate/itaconic acid/oligo (ethylene glycol) acrylate) terpolymeric hydrogels

    International Nuclear Information System (INIS)

    Micic, M.; Stamenic, D.; Suljovrujic, E.

    2012-01-01

    Since it is presumed that by incorporation of pH-responsive (IA) and temperature-responsive (OEGA) co-monomers, it is possible to prepare P(HEMA/IA/OEGA) hydrogels with dual (pH and thermo) responsiveness, the main purpose of our study is to investigate the influence of different mole fractions of IA and especially OEGA on the diversity of the swelling properties of the obtained hydrogels. For that reason, a series of terpolymeric hydrogels with different mole ratios of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and oligo(ethylene glycol) acrylates (OEGA) was synthesised by gamma radiation. The obtained hydrogels were characterised by swelling studies in the wide pH (2.2–9.0) and temperature range (20–70 °C), confirming dual (pH and thermo) responsiveness and a large variation in the swelling capability. It was observed that the equilibrium swelling of P(HEMA/IA/OEGA) hydrogels, for a constant amount of IA, increased progressively with an increase in OEGA share. On the other hand, the dissociation of carboxyl groups from IA occurs at pH>4; therefore, small mole fractions of IA render good pH sensitivity and a large increase in the swelling capacity of these hydrogels at higher pH values. Additional characterisation of structure and properties was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and mechanical measurements, confirming that the inherent properties of P(HEMA/IA/OEGA) hydrogels can be significantly tuned by variation in their composition. According to all presented, it seems that the obtained hydrogels can be a beneficial synergetic combination for controlled delivery of bioactive molecules such as drugs, peptides, proteins, etc. - Highlights: ► pH- and thermo-sensitive P(HEMA/IA/OEGA) hydrogels were synthesised by γ radiation. ► OEGA units have a large hydrophilic potential. ► Swelling capacity increases with the OEGA content. ► Variation in composition of hydrogels can give

  4. Direct laser writing of synthetic poly(amino acid) hydrogels and poly(ethylene glycol) diacrylates by two-photon polymerization

    International Nuclear Information System (INIS)

    Käpylä, Elli; Sedlačík, Tomáš; Aydogan, Dogu Baran; Viitanen, Jouko; Rypáček, František; Kellomäki, Minna

    2014-01-01

    The additive manufacturing technique of direct laser writing by two-photon polymerization (2PP-DLW) enables the fabrication of three-dimensional microstructures with superior accuracy and flexibility. When combined with biomimetic hydrogel materials, 2PP-DLW can be used to recreate the microarchitectures of the extracellular matrix. However, there are currently only a limited number of hydrogels applicable for 2PP-DLW. In order to widen the selection of synthetic biodegradable hydrogels, in this work we studied the 2PP-DLW of methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s). The performance of these materials was compared to widely used poly(ethylene glycol) diacrylates (PEGdas) in terms of polymerization and damage thresholds, voxel size, line width, post-polymerization swelling and deformation. We found that both methacryloylated and acryloylated poly(AA) hydrogels are suitable to 2PP-DLW with a wider processing window than PEGdas. The poly(AA) with the highest degree of acryloylation showed the greatest potential for 3D microfabrication. - Highlights: • Methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s) were synthesized. • Direct laser writing by two-photon polymerization (2PP-DLW) of poly(AA)s is shown. • Poly(AA)s have wider processing windows than poly(ethylene glycol) diacrylates. • 3D poly(AA) structures with 80% water content were fabricated

  5. Direct laser writing of synthetic poly(amino acid) hydrogels and poly(ethylene glycol) diacrylates by two-photon polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Käpylä, Elli, E-mail: elli.kapyla@tut.fi [Department of Electronics and Communications Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); BioMediTech, Biokatu 10, 33520 Tampere (Finland); Sedlačík, Tomáš [Institute of Macromolecular Chemistry of the Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Praha 6, Břevnov, Prague (Czech Republic); Aydogan, Dogu Baran [Department of Electronics and Communications Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); BioMediTech, Biokatu 10, 33520 Tampere (Finland); Viitanen, Jouko [VTT Technical Research Centre of Finland, P.O. Box 1300, 33101 Tampere (Finland); Rypáček, František [Institute of Macromolecular Chemistry of the Academy of Sciences of the Czech Republic, Heyrovského nám. 2, 162 06 Praha 6, Břevnov, Prague (Czech Republic); Kellomäki, Minna [Department of Electronics and Communications Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere (Finland); BioMediTech, Biokatu 10, 33520 Tampere (Finland)

    2014-10-01

    The additive manufacturing technique of direct laser writing by two-photon polymerization (2PP-DLW) enables the fabrication of three-dimensional microstructures with superior accuracy and flexibility. When combined with biomimetic hydrogel materials, 2PP-DLW can be used to recreate the microarchitectures of the extracellular matrix. However, there are currently only a limited number of hydrogels applicable for 2PP-DLW. In order to widen the selection of synthetic biodegradable hydrogels, in this work we studied the 2PP-DLW of methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s). The performance of these materials was compared to widely used poly(ethylene glycol) diacrylates (PEGdas) in terms of polymerization and damage thresholds, voxel size, line width, post-polymerization swelling and deformation. We found that both methacryloylated and acryloylated poly(AA) hydrogels are suitable to 2PP-DLW with a wider processing window than PEGdas. The poly(AA) with the highest degree of acryloylation showed the greatest potential for 3D microfabrication. - Highlights: • Methacryloylated and acryloylated poly(α-amino acid)s (poly(AA)s) were synthesized. • Direct laser writing by two-photon polymerization (2PP-DLW) of poly(AA)s is shown. • Poly(AA)s have wider processing windows than poly(ethylene glycol) diacrylates. • 3D poly(AA) structures with 80% water content were fabricated.

  6. Comparison of Polymer Networks Synthesized by Conventional Free Radical and RAFT Copolymerization Processes in Supercritical Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Patricia Pérez-Salinas

    2017-05-01

    Full Text Available There is a debate in the literature on whether or not polymer networks synthesized by reversible deactivation radical polymerization (RDRP processes, such as reversible addition-fragmentation radical transfer (RAFT copolymerization of vinyl/divinyl monomers, are less heterogeneous than those synthesized by conventional free radical copolymerization (FRP. In this contribution, the syntheses by FRP and RAFT of hydrogels based on 2-hydroxyethylene methacrylate (HEMA and ethylene glycol dimethacrylate (EGDMA in supercritical carbon dioxide (scCO2, using Krytox 157 FSL as the dispersing agent, and the properties of the materials produced, are compared. The materials were characterized by differential scanning calorimetry (DSC, swelling index (SI, infrared spectroscopy (FTIR and scanning electron microscopy (SEM. Studies on ciprofloxacin loading and release rate from hydrogels were also carried out. The combined results show that the hydrogels synthesized by FRP and RAFT are significantly different, with apparently less heterogeneity present in the materials synthesized by RAFT copolymerization. A ratio of experimental (Mcexp to theoretical (Mctheo molecular weight between crosslinks was established as a quantitative tool to assess the degree of heterogeneity of a polymer network.

  7. Poly (L-lactic acid) porous scaffold-supported alginate hydrogel with improved mechanical properties and biocompatibility.

    Science.gov (United States)

    Chu, Jiaqi; Zeng, Shaodong; Gao, Liyang; Groth, Thomas; Li, Zhiwen; Kong, Junchao; Zhao, Mingyan; Li, Lihua

    2016-10-10

    Polymer porous scaffolds and hydrogels have been separately employed and explored for a wide range of applications including cell encapsulation, drug delivery, and tissue engineering. In this study, a three-dimensional poly (L-lactic acid) (PLLA) scaffold with interconnected and homogeneously distributed pores was fabricated to support the alginate hydrogel (Alg). The gels were filled into the porous scaffold, which acted as an analogue of native extracellular matrix (ECM) for entrapment of cells within a support of predefined shape. The mechanical strength of the composite scaffold was characterized by compression testing. The chondrocyte behavior in the scaffold was determined by inverted microscopy, scanning electron microscopy (SEM) and MTT viability assay. The repair efficiency of such a composite scaffold was further investigated in dog spinal defects by histological evaluation after implantation for 4 weeks. Results showed that the composite scaffold possessed superior mechanical properties and hierarchical porous structure in comparison to pure Alg. Cell culture revealed that the cells presented a specific cartilage status in the composite scaffold in line with higher adherence and proliferation ratio. The histological analyses suggested that the composite scaffold substantially promotes its integration in the host tissue accompanied with a low inflammatory reaction and new tissue formation. The method thus provides a useful pathway for scaffold preparation that can simultaneously achieve suitable mechanical properties and good biocompatibility.

  8. Recovery of oxidative stress-induced damage in Cisd2-deficient cardiomyocytes by sustained release of ferulic acid from injectable hydrogel.

    Science.gov (United States)

    Cheng, Yung-Hsin; Lin, Feng-Huei; Wang, Chien-Ying; Hsiao, Chen-Yuan; Chen, Hung-Ching; Kuo, Hsin-Yu; Tsai, Ting-Fen; Chiou, Shih-Hwa

    2016-10-01

    Aging-related oxidative stress is considered a major risk factor of cardiovascular diseases (CVD) and could be associated with mitochondrial dysfunction and reactive oxygen species (ROS) overproduction. Cisd2 is an outer mitochondrial membrane protein and plays an important role in controlling the lifespan of mammals. Ferulic acid (FA), a natural antioxidant, is able to improve cardiovascular functions and inhibit the pathogenetic CVD process. However, directly administering therapeutics with antioxidant molecules is challenging because of stability and bioavailability issues. In the present study, thermosensitive chitosan-gelatin-based hydrogel containing FA was used to treat Cisd2-deficient (Cisd2(-/-)) cardiomyocytes (CM) derived from induced pluripotent stem cells of Cisd2(-/-) murine under oxidative stress. The results revealed that the developed hydrogel could provide a sustained release of FA and increase the cell viability. Post-treatment of FA-loaded hydrogel effectively decreased the oxidative stress-induced damage in Cisd2(-/-) CM via increasing catalase activity and decreasing endogenous reactive oxygen species (ROS) production. The in vivo biocompatibility of FA-loaded hydrogel was confirmed in subcutaneously injected rabbits and intramyocardially injected Cisd2(-/-) mice. These results suggest that the thermosensitive FA-loaded hydrogel could rescue Cisd2(-/-) CM from oxidative stress-induced damage and may have potential applications in the future treatment of CVD. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Phase separation of in situ forming poly (lactide-co-glycolide acid) implants investigated using a hydrogel-based subcutaneous tissue surrogate and UV-vis imaging.

    Science.gov (United States)

    Sun, Yu; Jensen, Henrik; Petersen, Nickolaj J; Larsen, Susan W; Østergaard, Jesper

    2017-10-25

    Phase separation of in situ forming poly (lactide-co-glycolide acid) (PLGA) implants with agarose hydrogels as the provider of nonsolvent (water) mimicking subcutaneous tissue was investigated using a novel UV-vis imaging-based analytical platform. In situ forming implants of PLGA-1-methyl-2-pyrrolidinone and PLGA-triacetin representing fast and slow phase separating systems, respectively, were evaluated using this platform. Upon contact with the agarose hydrogel, the phase separation of the systems was followed by the study of changes in light transmission and absorbance as a function of time and position. For the PLGA-1-methyl-2-pyrrolidinone system, the rate of spatial phase separation was determined and found to decrease with increasing the PLGA concentration from 20% to 40% (w/w). Hydrogels with different agarose concentrations (1% and 10% (w/v)) were prepared for providing the nonsolvent, water, to the in situ forming PLGA implants simulating the injection site environment. The resulting implant morphology depended on the stiffness of hydrogel matrix, indicating that the matrix in which implants are formed is of importance. Overall, the work showed that the UV-vis imaging-based platform with an agarose hydrogel mimicking the subcutaneous tissue holds potential in providing bio-relevant and mechanistic information on the phase separation processes of in situ forming implants. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. The release behavior and kinetic evaluation of tramadol HCl from chemically cross linked Ter polymeric hydrogels.

    Science.gov (United States)

    Malana, Muhammad A; Zohra, Rubab

    2013-01-18

    Hydrogels, being stimuli responsive are considered to be effective for targeted and sustained drug delivery. The main purpose for this work was to study the release behavior and kinetic evaluation of Tramadol HCl from chemically cross linked ter polymeric hydrogels. Ter-polymers of methacrylate, vinyl acetate and acrylic acid cross linked with ethylene glycol dimethacrylate (EGDMA) were prepared by free radical polymerization. The drug release rates, dynamic swelling behavior and pH sensitivity of hydrogels ranging in composition from 1-10 mol% EGDMA were studied. Tramadol HCl was used as model drug substance. The release behavior was investigated at pH 8 where all formulations exhibited non-Fickian diffusion mechanism. Absorbency was found to be more than 99% indicating good drug loading capability of these hydrogels towards the selected drug substance. Formulations designed with increasing amounts of EGDMA had a decreased equilibrium media content as well as media penetrating velocity and thus exhibited a slower drug release rate. Fitting of release data to different kinetic models indicate that the kinetic order shifts from the first to zero order as the concentration of drug was increased in the medium, showing gradual independency of drug release towards its concentration. Formulations with low drug content showed best fitness with Higuchi model whereas those with higher concentration of drug followed Hixson-Crowell model with better correlation values indicating that the drug release from these formulations depends more on change in surface area and diameter of tablets than that on concentration of the drug. Release exponent (n) derived from Korse-Meyer Peppas equation implied that the release of Tramadol HCl from these formulations was generally non-Fickian (n > 0.5 > 1) showing swelling controlled mechanism. The mechanical strength and controlled release capability of the systems indicate that these co-polymeric hydrogels have a great potential to

  11. A comparative study on the graft copolymerization of acrylic acid onto rayon fibre by a ceric ion redox system and a γ-radiation method.

    Science.gov (United States)

    Kaur, Inderjeet; Kumar, Raj; Sharma, Neelam

    2010-10-13

    Functionalization of rayon fibre has been carried out by grafting acrylic acid (AAC) both by a chemical method using a Ce(4+)-HNO(3) redox initiator and by a mutual irradiation (γ-rays) method. The reaction conditions affecting the grafting percentage have been optimized for both methods, and the results are compared. The maximum percentage of grafting (50%) by the chemical method was obtained utilizing 18.24 × 10(-3) moles/L of ceric ammonium nitrate (CAN), 39.68 × 10(-2) moles/L of HNO(3), and 104.08 × 10(-2) moles/L of AAc in 20 mL of water at 45°C for 120 min. For the radiation method, the maximum grafting percentage (60%) was higher, and the product was obtained under milder reaction conditions using a lower concentration of AAc (69.38 × 10(-2) moles/L) in 10 mL of water at an optimum total dose of 0.932 kGy. Swelling studies showed higher swelling for the grafted rayon fibre in water (854.54%) as compared to the pristine fibre (407%), while dye uptake studies revealed poor uptake of the dye (crystal violet) by the grafted fibre in comparison with the pristine fibre. The graft copolymers were characterized by IR, TGA, and scanning electron micrographic methods. Grafted fibre, prepared by the radiation-induced method, showed better thermal behaviour. Comparison of the two methods revealed that the radiation method of grafting of acrylic acid onto rayon fibre is a better method of grafting in comparison with the chemical method. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Zhaoxin, L; Fujimura, T

    2000-12-01

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

  13. Olefin copolymerization via controlled radical polymerization : copolymerization of methyl methacrylate and 1-octene

    NARCIS (Netherlands)

    Venkatesh, R.; Klumperman, B.

    2004-01-01

    The atom transfer radical (co)polymerization (ATRP) of methyl methacrylate (MMA) with 1-octene was investigated. Well controlled homopolymer of MMA was obtained with 2,2,2-trichoroethanol (TCE) and p-toluenesulfonyl chloride (pTsCl), although, uncontrolled copolymerization occurred when pTsCl was

  14. Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.

    Science.gov (United States)

    Hu, Pengbing; Dong, Xinyong; Wong, Wei Chang; Chen, Li Han; Ni, Kai; Chan, Chi Chiu

    2015-04-01

    We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response.

  15. Ion-recognizable hydrogels for efficient removal of cesium ions from aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hai-Rong [School of Chemical Engineering, Sichuan University, No. 24, Southern 1 Section, Yihuan Road, Chengdu, Sichuan, 610065 (China); College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, No. 16, Southern 4 Section, Yihuan Road, Chengdu, Sichuan, 610041 (China); Hu, Jia-Qi [School of Chemical Engineering, Sichuan University, No. 24, Southern 1 Section, Yihuan Road, Chengdu, Sichuan, 610065 (China); Liu, Zhuang, E-mail: liuz@scu.edu.cn [School of Chemical Engineering, Sichuan University, No. 24, Southern 1 Section, Yihuan Road, Chengdu, Sichuan, 610065 (China); Ju, Xiao-Jie; Xie, Rui; Wang, Wei [School of Chemical Engineering, Sichuan University, No. 24, Southern 1 Section, Yihuan Road, Chengdu, Sichuan, 610065 (China); State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065 (China); Chu, Liang-Yin, E-mail: chuly@scu.edu.cn [School of Chemical Engineering, Sichuan University, No. 24, Southern 1 Section, Yihuan Road, Chengdu, Sichuan, 610065 (China); State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065 (China); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing, Jiangsu 211816 (China)

    2017-02-05

    Highlights: • An easy-to-get and low-cost Cs{sup +}-recognizable polymeric hydrogel has been developed. • The hydrogel displays rapid and selective adsorption towards Cs{sup +}. • Synergistic effect of AAc units and Cs{sup +}(B18C6){sub 2} host-guest complexes is good for adsorption. • The hydrogel shows great potential for decontamination of Cs{sup +} from radioactive contaminants. - Abstract: At present, selective and efficient removal of cesium ions (Cs{sup +}) from nuclear waste is of significant importance but still challenging. In this study, an easy-to-get and low-cost hydrogel adsorbent has been developed for effective adsorption and removal of Cs{sup +} from aqueous environment. The novel Cs{sup +}-recognizable poly(acrylic acid-co-benzo-18-crown-6-acrylamide) (poly(AAc-co-B18C6Am)) hydrogel is specifically designed with a synergistic effect, in which the AAc units are designed to attract Cs{sup +} via electrostatic attraction and the B18C6Am units are designed to capture the attracted Cs{sup +} by forming stable 2:1 “sandwich” complexes. The poly(AAc-co-B18C6Am) hydrogels are simply synthesized by thermally initiated free-radical copolymerization and display excellent Cs{sup +} adsorption from commonly coexisting metal ions. Important parameters affecting the adsorption are investigated comprehensively, and the adsorption kinetics and adsorption isotherms are also discussed systematically. The poly(AAc-co-B18C6Am) hydrogels exhibit rapid Cs{sup +} adsorption within 30 min and the adsorption process is governed by the pseudo-second order model. Adsorption isotherm results demonstrate that the equilibrium data are well fitted by the Langmuir isotherm model, indicating that the Cs{sup +} adsorption is probably a monolayer adsorption process. Such Cs{sup +}-recognizable hydrogel materials based on the host-guest complexation are promising as efficient and feasible candidates for adsorption and removal of radioactive Cs{sup +} from nuclear

  16. The Influence of Stabilized Deconjugated Ursodeoxycholic Acid on Polymer-Hydrogel System of Transplantable NIT-1 Cells.

    Science.gov (United States)

    Mooranian, Armin; Negrulj, Rebecca; Al-Salami, Hani

    2016-05-01

    The encapsulation of pancreatic β-cells in biocompatible matrix has generated great interest in diabetes treatment. Our work has shown improved microcapsules when incorporating the bile acid ursodeoxycholic acid (UDCA), in terms of morphology and cell viability although cell survival remained low. Thus, the study aimed at incorporating the polyelectrolytes polyallylamine (PAA) and poly-l-ornithine (PLO), with the polymer sodium alginate (SA) and the hydrogel ultrasonic gel (USG) with UDCA and examined cell viability and functionality post microencapsulation. Microcapsules without (control) and with UDCA (test) were produced using 1% PLO, 2.5% PAA, 1.8% SA and 4.5% USG. Pancreatic β-cells were microencapsulated and the microcapsules' morphology, surface components, cellular and bile acid distribution, osmotic and mechanical stability as well as biocompatibilities, insulin production, bioenergetics and the inflammatory response were tested. Incorporation of UDCA at 4% into a PLO-PAA-SA formulation system increased cell survival (p acid UDCA (4%) has good potential in cell transplantation and diabetes treatment.

  17. Mucoadhesive hydrogel microparticles based on poly (methacrylic acid-vinyl pyrrolidone)-chitosan for oral drug delivery.

    Science.gov (United States)

    Sajeesh, S; Sharma, Chandra P

    2011-05-01

    The study was aimed at the evaluation of N-vinyl pyrrolidone (NVP) incorporated polymethacrylic acid-chitosan microparticles for oral drug delivery applications. Poly (methacrylic acid)-chitosan (PMC) and poly(methacrylic acid-vinyl pyrrolidone)-chitosan (PMVC) microparticles were prepared by an ionic-gelation method. Mucoadhesion behaviour of these particles was evaluated by ex-vivo adhesion method using freshly excised rat intestinal tissue. Cytotoxicity and absorption enhancing property of PMC and PMVC particles were evaluated on Caco 2 cell monolayers. Protease enzyme inhibition capability and insulin loading/release properties of these hydrogel particles was evaluated under in vitro experimental conditions. Addition of NVP units enhanced the mucoadhesion behavior of PMC particles on isolated rat intestinal tissue. Both PMC and PMVC particles were found non-toxic on Caco 2 cell monolayers and PMC particles was more effective in improving paracellular transport of fluorescent dextran across Caco 2 cell monolayers as compared to PMVC particles. However, protease inhibition efficacy of PMC particles was not significantly affected with NVP addition. NVP incorporation improved the insulin release properties of PMC microparticles at acidic pH. Hydrophilic modification seems to be an interesting approach in improving mucoadhesion capability of PMC microparticles.

  18. Synthesis and characterization of high performance superabsorbent hydrogels using bis[2-(methacryloyloxyethyl] phosphate as crosslinker

    Directory of Open Access Journals (Sweden)

    A. A. L. Goncalves

    2016-03-01

    Full Text Available Various superabsorbent polymers (SAPs were synthesized by free radical copolymerization at 70°C using acrylic acid (AA, potassium acrylate (KA, N-isopropyl acrylamide (NIPAM and sulfopropyl methacrylate potassium salt (SPM as monomers, bis[2-(methacryloyloxyethyl] phosphate (BMEP as crosslinker and potassium persulfate (KPS as initiator. The optimization of the synthesis led to the preparation of a SAP with very high water absorption ability, with a maximum swelling of 2618 g water/g dry hydrogel. The most promising SAP was fully characterized and the absorption capacities were studied at different pH and ionic strengths. When this SAP was mixed with soil, the mixture was able to lose water more slowly. Also, this material revealed high loading capacity and showed good releasing profiles using urea as model fertilizer. Due to these advantageous properties, the synthesized SAP can be used in agricultural applications.

  19. A study on the effect of the concentration of N,N-methylenebisacrylamide and acrylic acid toward the properties of Dioscorea hispida-starch-based hydrogel

    Science.gov (United States)

    Ashri, Airul; Lazim, Azwan

    2014-09-01

    The research investigated the effects of acrylic acid (monomer) and N,N,-methylenebisacrylamide, MBA (crosslinker) toward the percentage of gel content, swelling ratio and ionic strength of a starch-based hydrogel. Starch grafted on poly (sodium acrylate), St-g-PAANa hydrogel was prepared by incorporating starch extracted from Dioscorea hispida in NaOH/aqueous solution using different composition of acrylic acid (AA) and N,N-methylenebisacrylamide (MBA) in the presence of potassium persulfate (KPS) as chemical initiator. The highest gel content was observed at 1:30 ratio of starch to AA and 0.10 M of MBA. Results showed the highest swelling ratio was observed at 1:15 ratio of starch to acrylic acid and 0.02 M of MBA solution. The same results also gave the highest swelling ratio for the ionic strength study. The FTIR analysis was also conducted in order to confirm the grafting of AA onto starch backbone.

  20. A hydrogel actuator with flexible folding deformation and shape programming via using sodium carboxymethyl cellulose and acrylic acid.

    Science.gov (United States)

    Wu, Shuiping; Yu, Feng; Dong, Hua; Cao, Xiaodong

    2017-10-01

    Hydrogel actuator is an intelligent material, which can work as artificial muscle. However, most present hydrogel actuators, due to the inferior mechanical property and uncontrolled folding property, have always resulted in slipping off or the failure of grasping an object with specific shape and required weight. In order to solve this problem, here a tough hydrogel actuator with programmable folding deformation has been prepared by combining the "selective implanting method" and "ionic coordination". The shape and folding angle (from 0 to 180 o ) of hydrogel actuator can be precisely controlled by altering the location and size of the implanting parts that seems like the joints of finger. The ionic coordination is not only the force to trigger the folding of hydrogel, but also utilized to reinforce the mechanical property. We believed the superior mechanical and shape-programmable property can endow the hydrogel actuator with great application prospect in soft machine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols.

    Science.gov (United States)

    Couturier, Jean-Philippe; Wischerhoff, Erik; Bernin, Robert; Hettrich, Cornelia; Koetz, Joachim; Sütterlin, Martin; Tiersch, Brigitte; Laschewsky, André

    2016-05-03

    Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers' cloud point, or the induced changes of the hydrogels' swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye.

  2. Synthesis, characterization and rheological behavior of pH sensitive poly(acrylamide-co-acrylic acid hydrogels

    Directory of Open Access Journals (Sweden)

    Seddiki Nesrinne

    2017-05-01

    Results indicated that the strong interaction in the hydrogels resulted in the formation of a more stable copolymer. The single glass transition temperature (Tg in sample suggested that the two polymers into the hydrogel have a good miscibility. The elastic modulus (G′ and linear viscoelastic region increased with increase in PAAc concentration. The oscillation time sweep study of the hydrogels exhibited a flat G′ indicating a stable structure and good mechanical strength. In the swelling measurements, the gels exhibited appreciable water uptake and were highly sensitive to pH environment. So the poly(AAm-co-AAc hydrogel will have promising application in pharmaceutical use and in biomaterials.

  3. Automated batch emulsion copolymerization of styrene and butyl acrylate

    NARCIS (Netherlands)

    Mballa Mballa, M.A.; Schubert, U.S.; Heuts, J.P.A.; Herk, van A.M.

    2011-01-01

    This article describes a method for carrying out emulsion copolymerization using an automated synthesizer. For this purpose, batch emulsion copolymerizations of styrene and butyl acrylate were investigated. The optimization of the polymerization system required tuning the liquid transfer method,

  4. Radiation-induced copolymerization of α,β,β-trifluoroacrylonitrile with α-olefin

    International Nuclear Information System (INIS)

    Matsuda, O.; Kostov, G.K.; Tabata, Y.; Machi, S.

    1979-01-01

    Homopolymerization and copolymerization of α,β,β-trifluoroacrylonitrile (FAN) with α-olefins were carried out in bulk by γ-ray irradiation at 25 0 C. FAN gives very small quantities of brown and greasy low molecular weight polymer. Cyano groups in FAN polymer were found to be readily hydrolyzed to acid amide groups in the atmosphere. FAN was found to copolymerize with ethylene, propylene, and isobutylene via a radical mechanism to form equimolar copolymers in a wide range of monomer compositions. The polymerization rate increases linearly with FAN fraction in the monomer mixture. These copolymers are also hydrolyzed in the atmosphere, and the hydrolysis proceeds with more difficulty for the copolymer with higher α-olefin. The reactivity ratios r 1 (FAN) and r 2 (α-olefin) were determined to be 0.01 and 0.12 for the FAN/ethylene copolymerization and 0.01 and 0.07 for the FAN/propylene copolymerization. These results confirm that an alternating copolymerization takes place in the FAN/α-olefin system

  5. Study of poly (acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid) hydrogel using gamma radiation initiation

    International Nuclear Information System (INIS)

    Zhang, C.; Easteal, A.J.

    1998-01-01

    Full text: Poly (acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid ) (PAAM-co-AMPS) polyelectrolyte hydrogels were formed by using γ-radiation to initiate polymerization and cross-linking. The dependence of chain growth and cross-linking of liquid-like gel on absorbed dose was observed by viscosity measurement. It was found that the viscosity of liquid-like gel increased non-linearly with increasing radiation dose. Crosslinking took place at about 2,300 Gy. It was noted that an ageing effect occurred, such that the viscosity of liquid-like gels decreased significantly on standing. X-ray diffraction revealed that after dehydration the dried gels were amorphous, suggesting that radiation polymerization occurs by random initiation and propagation. Differential scanning calorimetry (DSC) indicated a clear distinction between the thermal behaviour of the homopolymer gels formed by irradiation, and the behaviour of the copolymer gels. PAAM-co-AMPS gels have enhanced thermal stability in comparison to PAAM and PAMPS. The melting points of water in the gels initially increase with increasing dose, and decrease slightly at very high radiation dose. Those trends can be explained by the variation in the numbers of solute molecules or ions in the gels with absorbed dose. Melting points of water in gels can be used for observation of the polymerization process associated with irradiation. Copolymer composition (expressed by either f 1 (AAM molal fraction ) or f 2 (AMPS molal fraction) ) associated with radiation dose was determined by both elemental analysis and FTIR. Both methods show that f 1 increases to a maximum with increasing dose, and subsequently decreases. It is concluded that PAAM-co-AMPS hydrogels were synthesised successfully by gamma radiation initiation, and that copolymer compositions are dependent on radiation dose

  6. Ruthenium phosphine complexes as catalysts for alternating co-polymerization of ethylene and CO

    International Nuclear Information System (INIS)

    Gusev, O.V.; Kal'sin, A.M.; Peganov, T.A.; Petrovskij, P.V.; Belov, G.P.; Novikova, E.V.

    2000-01-01

    Ruthenium (2) complexes, [Ru(dppe) 2 (OTs) 2 ] and [Ru(PhP(CH 2 CH 2 CH 2 PPh 2 ) 2 )(OTs) 2 ], where dppe (diphenylphosphino)ethane; OTs = tosylate, were synthesized with the yield of 67 and 76%, respectively, and characterized by 31 P NMR. The properties of the above complexes as catalysts of alternating co-polymerization of ethylene and carbon monoxide were studied. A considerable increase in catalytic activity of the complexes was established in the presence of trifluoroacetic acid and 1,4-benzoquinone. These compounds are the first example of ruthenium complexes that catalyse co-polymerization of ethylene and CO [ru

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

    Science.gov (United States)

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

    2015-06-20

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

  8. Enhancing both the mechanical and chemical properties of paper sheet by graft co-polymerization with acrylonitrile/methyl methacrylate

    Directory of Open Access Journals (Sweden)

    H.M. Abd El Salam

    2014-09-01

    Full Text Available The chemical graft copolymerization reaction of acrylonitrile (AN and methyl methacrylate (MMA binary mixture onto paper sheet was performed. The effect of initiator concentration, monomer concentration and temperature on the reaction rate was studied. The reaction rate equation of the graft copolymerization reaction is found to be RP = K2 [Initiator]0.795[Monomer]2.007. The apparent activation energy (Ea of the copolymerization reaction is found to be 75.01 kJ/mol. The infrared characteristic absorption bands for cellulosic paper structure and the paper gr-AN-MMA are investigated. Tensile break load, porosity and burst strength were measured for the grafted and pure paper sheet. It was found that the mechanical properties are improved by grafting copolymerization. The chemical resistance of the graft product against a strong acid a strong alkali, polar and nonpolar solvents was investigated. It was found that the resistance to these chemicals is enhanced by grafting.

  9. An experimental test of stroke recovery by implanting a hyaluronic acid hydrogel carrying a Nogo receptor antibody in a rat model

    International Nuclear Information System (INIS)

    Ma Jun; Tian Weiming; Hou Shaoping; Xu Qunyuan; Spector, Myron; Cui Fuzhai

    2007-01-01

    The objective of the study was to determine the effects of a hyaluronic-acid-based (HA-based) hydrogel implant, carrying a polyclonal antibody to the Nogo-66 receptor (NgR), on adult rats that underwent middle cerebral artery occlusion (MCAO). Behavioral tests of a forelimb-reaching task suggested that the disabled function of the impaired forelimb in this stroke model was ameliorated by the implant to a certain extent. These behavioral findings were correlated with immunohistochemical results of investigating the distribution of NgR antibody, neurofilaments (NF) and neuron-specific class III β-tubulin (TuJ1) in the brain sections. The porous hydrogel functioned as a scaffold to deliver the NgR antibody, support cell migration and development. In addition, it was found NF-positive and TuJ1-positive expressions were distributed in the implanted hydrogel. Collectively, the results demonstrate the promise of the HA hydrogel as a scaffold material and the delivery vehicle of the NgR antibody for the repair of defects and the support of neural regeneration in the brain

  10. An experimental test of stroke recovery by implanting a hyaluronic acid hydrogel carrying a Nogo receptor antibody in a rat model

    Energy Technology Data Exchange (ETDEWEB)

    Ma Jun [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Tian Weiming [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Hou Shaoping [Beijing Institute of Neuroscience, Capital University of Medical Sciences, Beijing 100054 (China); Xu Qunyuan [Beijing Institute of Neuroscience, Capital University of Medical Sciences, Beijing 100054 (China); Spector, Myron [Tissue Engineering, VA Boston Healthcare System, Harvard Medical School, Boston, MA (United States); Cui Fuzhai [Biomaterials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2007-12-15

    The objective of the study was to determine the effects of a hyaluronic-acid-based (HA-based) hydrogel implant, carrying a polyclonal antibody to the Nogo-66 receptor (NgR), on adult rats that underwent middle cerebral artery occlusion (MCAO). Behavioral tests of a forelimb-reaching task suggested that the disabled function of the impaired forelimb in this stroke model was ameliorated by the implant to a certain extent. These behavioral findings were correlated with immunohistochemical results of investigating the distribution of NgR antibody, neurofilaments (NF) and neuron-specific class III {beta}-tubulin (TuJ1) in the brain sections. The porous hydrogel functioned as a scaffold to deliver the NgR antibody, support cell migration and development. In addition, it was found NF-positive and TuJ1-positive expressions were distributed in the implanted hydrogel. Collectively, the results demonstrate the promise of the HA hydrogel as a scaffold material and the delivery vehicle of the NgR antibody for the repair of defects and the support of neural regeneration in the brain.

  11. A hydrogel-mediated scalable strategy toward core-shell polyaniline/poly(acrylic acid)-modified carbon nanotube hybrids as efficient electrodes for supercapacitor applications

    Science.gov (United States)

    Liu, Qingqing; Bai, Zhengyu; Fan, Jingbiao; Sun, Zhipeng; Mi, Hongyu; Zhang, Qing; Qiu, Jieshan

    2018-04-01

    Structural failure of polyaniline (PANI) stemmed from repeated swelling-shrinkage during Faradic process represents an imminent issue hindering the real application of this material for advanced energy storage. Herein, we explore a clean and facile hydrogel-mediated layer-by-layer strategy to conformally coat a layer of oriented PANI nanofibers on multi-walled carbon nanotubes (MWCNTs) where a layer of UV-polymerized poly(acrylic acid) (PAA) hydrogel is first formed in between as electrodes for supercapacitors. Such an intriguing core-shell tri-component structure perfectly alleviates the drawbacks of PANI as well as combines the advantages of MWCNTs. Especially, the hydrogel used increases the adhesion between PANI and MWCNTs, buffers the structural variation of PANI during cycling, and provide extra driving force accelerating electrolyte penetration throughout active materials. Therefore, the well-intergrown hybrids (PANI/P-MWCNT) display high electrochemical performance as compared to PANI and PANI/MWCNT, i.e., an improved capacitance of 612.5 F g-1 at 0.5 A g-1, and excellent cycling behavior of 81.5% capacitance retention at 5 A g-1 over 1500 cycles. Also, the maximum energy density of the PANI/P-MWCNT based symmetric configuration reaches 8.2 Wh kg-1. Significantly, such a hydrogel-bridged design concept may find the important application for the synthesis of competitive candidates for energy storage.

  12. SYNTHESIS AND IN VITRO CHARACTERIZATION OF HYDROXYPROPYL METHYLCELLULOSE-GRAFT-POLY (ACRYLIC ACID/2-ACRYLAMIDO-2-METHYL-1-PROPANESULFONIC ACID) POLYMERIC NETWORK FOR CONTROLLED RELEASE OF CAPTOPRIL.

    Science.gov (United States)

    Furqan Muhammad, Iqbal; Mahmood, Ahmad; Aysha, Rashid

    2016-01-01

    A super-absorbent hydrogel was developed by crosslinking of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and acrylic acid with hydroxypropyl methylcellulose (HPMC) for controlled release drug delivery of captopril, a well known antihypertensive drug. Acrylic acid and AMPS were polymerized and crosslinked with HPMC by free radical polymerization, a widely used chemical crosslinking method. N,N'-methylenebisacrylamide (MBA) and potassium persulfate (KPS) were added as cross-linker and initiator, respectively. The hydrogel formulation was loaded with captopril (as model drug). The concentration of captopril was monitored at 205 nm using UV spectrophotometer. Equilibrium swelling ratio was determined at pH 2, 4.5 and 7.4 to evaluate the pH responsiveness of the formed hydrogel. The super-absorbent hydrogels were evaluated by FTIR, SEM, XRD, and thermal analysis (DSC and TGA). The formation of new copolymeric network was determined by FTIR, XRD, TGA and DSC analysis. The hydrogel formulations with acrylic acid and AMPS ratio of 4: 1 and lower amounts of crosslinker had shown maximum swelling. Moreover, higher release rate of captopril was observed at pH 7.4 than at pH 2, because of more swelling capacity of copolymer with increasing pH of the aqueous medium. The present research work confirms the development of a stable hydrogel comprising of HPMC with acrylic acid and AMPS. The prepared hydrogels exhibited pH sensitive behav-ior. This superabsorbent composite prepared could be a successful drug carrier for treating hypertension.

  13. Radiation copolymerization of tributyltin methacrylate and methylmathacrylate

    International Nuclear Information System (INIS)

    Zhao Binxi; Zhu Xiaohong; Murat; Han Zhewen

    1987-01-01

    The copolymer of tributytin methacrylate and methylmethacrylate is a useful self-polishing antifouling paints materials. It was synthesized by radiation polymerization using 60 Co γ ray at room temperature. The copolymerization kinetics of the pair of monomers was studied. The relationship between the reaction rate and the dose rate was found to be R p = K p ·I -053 and the reactivity ratios were measured to be less than 1. The overall activition energy was 1.29 x 10 4 J/mol. It was supposed that the copolymerization was of radical machanism

  14. A hyaluronic acid-based hydrogel enabling CD44-mediated chondrocyte binding and gapmer oligonucleotide release for modulation of gene expression in osteoarthritis

    DEFF Research Database (Denmark)

    Cai, Yunpeng; López-Ruiz, Elena; Wengel, Jesper

    2017-01-01

    Hyaluronic acid (HA) is an attractive biomaterial for osteoarthritis (OA) treatment due to inherent functional and compatibility properties as an endogenous knee joint component. In this work, we describe a HA-based hydrogel with the dual functionality of increased CD44-dependent chondrocyte......:3) for identifying designs displaying optimal engagement of OA patient-derived CD44-expressing chondrocytes. Correlation was found between cell binding and CD44 expression, with maximal binding exhibited at a HA/chitosan ratio of 7:3, that was 181% higher than CD44-negative MCF-7 cell control cells. Transfection...... agent-free uptake into OA chondrocytes of fluorescent 13-mer DNA oligonucleotides with a flanked locked nucleic acid (LNA) gapmer design, in contrast to naked siRNA, was demonstrated by confocal and flow cytometric analysis. A sustained and complete release over 5days was found with the 7:3 hydrogel...

  15. Effect of stiffness of chitosan-hyaluronic acid dialdehyde hydrogels on the viability and growth of encapsulated chondrocytes.

    Science.gov (United States)

    V Thomas, Lynda; Vg, Rahul; D Nair, Prabha

    2017-11-01

    Substrate elasticity or stiffness can influence the phenotypic and functional characteristics of chondrocytes. This work aimed to study the effect of varying stiffness compositions of a two-component injectable hydrogel based on chitosan (CH) and oxidized hyaluronic acid (HDA) on the growth and functionality of encapsulated chondrocytes. Three different ratios of the gel were prepared (10:1,10:3 and 10:5 CH-HDA) and characterized. The stiffness of the gels was evaluated from the force displacement curves using force spectroscopy AFM analysis. Rabbit articular chondrocytes were harvested and the cells from Passage 2 to 4 were used for the encapsulation study. The viability and ECM production of encapsulated chondrocytes were assessed at 7day, 14day and 28day post culture. The results of the study show that as the ratio of hyaluronic acid dialdehyde component was increased, the stiffness of the gels increased from 130.78±19.83kPa to 181.47±19.77kPa which was also evidenced from the decrease in gelling time. Although there was an increase in the percentage of viable encapsulated cells which also maintained the spherical phenotype in the less stiff gels, decreased expression of ECM markers- Collagen type II and Glycosaminoglycans was observed compared to the stiffer gels. These findings indicate that gel stiffness strongly impacts the chondrocyte microenvironment both in maintenance of phenotypic integrity and ECM production. Copyright © 2017. Published by Elsevier B.V.

  16. Cadmium sulfide quantum dots/poly(acrylic acid-co-acrylic amide) composite hydrogel synthesized by gamma irradiation

    Science.gov (United States)

    Yang, Tao; Li, Qing; Wen, Wanxin; Hu, Liang; He, Weiwei; Liu, Hanzhou

    2018-04-01

    To improve the durability and stability of quantum dots (QDs) in the composite hydrogel, an irradiation induced reduction and polymerization-crosslinking method was reported herein where CdS QDs could be synthesized in situ and fastened to polymer chains due to the coordination forces between amino groups and CdS nanoparticles. The morphology and photoluminescence (PL) property of the composite hydrogel were studied. The result indicated that the CdS QDs with uniform size were dispersed evenly in the composite hydrogel, and the introduced CdS QDs had no obvious effect on the hydrogel structure. With the increases of reagent concentrations, PL intensity of the composite hydrogel was enhanced; however, the emission wavelength had no change.

  17. Physicochemical properties of pH-sensitive hydrogels based on hydroxyethyl cellulose-hyaluronic acid and for applications as transdermal delivery systems for skin lesions.

    Science.gov (United States)

    Kwon, Soon Sik; Kong, Bong Ju; Park, Soo Nam

    2015-05-01

    We investigated the physicochemical properties of pH-sensitive hydroxyethyl cellulose (HEC)/hyaluronic acid (HA) complex hydrogels containing isoliquiritigenin (ILTG), and discussed potential applications as transdermal delivery systems for the treatment of skin lesions caused by pH imbalance. HA has skin compatibility and pH functional groups and HEC serves as scaffold to build hydrogels with varied HCE:HA mass ratio. Hydrogels were synthesized via chemical cross-linking, and three-dimensional network structures were characterized via scanning electron microscopy (SEM). The swelling properties and polymer ratios of the hydrogels were investigated at pH values in the range 1-13. HECHA13 (i.e., an HEC:HA mass ratio of 1:3) was found to have optimal rheological and adhesive properties, and was used to investigate the drug release efficiency as a function of pH; the efficiency was greater than 70% at pH 7. Antimicrobial activity assays against Propionibacterium acnes were conducted to take advantage of the pH-sensitive properties of HECHA13. At pH 7, we found that HECHA13, which contained ILTG, inhibited the growth of P. acnes. Furthermore, HECHA13 was found to exhibit excellent permeability into the skin, which penetrated mostly via the hair follicle. These results indicate that this pH-sensitive hydrogel is effective as a transdermal delivery system for antimicrobial therapeutics, with potential applications in the treatment of acne. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. pH responsive N-succinyl chitosan/Poly (acrylamide-co-acrylic acid hydrogels and in vitro release of 5-fluorouracil.

    Directory of Open Access Journals (Sweden)

    Shahid Bashir

    Full Text Available There has been significant progress in the last few decades in addressing the biomedical applications of polymer hydrogels. Particularly, stimuli responsive hydrogels have been inspected as elegant drug delivery systems capable to deliver at the appropriate site of action within the specific time. The present work describes the synthesis of pH responsive semi-interpenetrating network (semi-IPN hydrogels of N-succinyl-chitosan (NSC via Schiff base mechanism using glutaraldehyde as a crosslinking agent and Poly (acrylamide-co-acrylic acid(Poly (AAm-co-AA was embedded within the N-succinyl chitosan network. The physico-chemical interactions were characterized by Fourier transform infrared (FTIR, X-ray diffraction (XRD, thermogravimetric analysis (TGA, and field emission scanning electron microscope (FESEM. The synthesized hydrogels constitute porous structure. The swelling ability was analyzed in physiological mediums of pH 7.4 and pH 1.2 at 37°C. Swelling properties of formulations with various amounts of NSC/ Poly (AAm-co-AA and crosslinking agent at pH 7.4 and pH 1.2 were investigated. Hydrogels showed higher swelling ratios at pH 7.4 while lower at pH 1.2. Swelling kinetics and diffusion parameters were also determined. Drug loading, encapsulation efficiency, and in vitro release of 5-fluorouracil (5-FU from the synthesized hydrogels were observed. In vitro release profile revealed the significant influence of pH, amount of NSC, Poly (AAm-co-AA, and crosslinking agent on the release of 5-FU. Accordingly, rapid and large release of drug was observed at pH 7.4 than at pH 1.2. The maximum encapsulation efficiency and release of 5-FU from SP2 were found to be 72.45% and 85.99%, respectively. Kinetics of drug release suggested controlled release mechanism of 5-FU is according to trend of non-Fickian. From the above results, it can be concluded that the synthesized hydrogels have capability to adapt their potential exploitation as targeted oral drug

  19. Synthesis and characterization of chitosan-graft-poly(acrylic acid)/rice husk ash hydrogels composites; Sintese e caracterizacao de hidrogeis compositos de cinza da casca de arroz e quitosana enxertada com poli(acido acrilico)

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Francisco H.A. [Universidade Estadual Vale do Acarau - UVA, Sobral, CE (Brazil); Lopes, Gabriel V.; Pereira, Antonio G.B.; Fajardo, Andre R.; Muniz, Edvani C. [Universidade Estadual de Maringa - UEM, PR (Brazil)

    2011-07-01

    According to environmental concerns, super absorbent hydrogel composites were synthesized based on rice husk ash (RHA), an industrial waste, and Chitosan-graft-poly(acrylic acid). The WAXS and FTIR data confirmed the syntheses of hydrogel composites. The effect of crystalline or amorphous RHA on water uptake was investigated. It was found that the RHA in crystalline form induces higher water capacity (W{sub eq}) of composites hydrogels due to the fact that the intra-interactions among silanol groups on RHA make available new sites in the polymer matrix, which could interact to water. (author)

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

    Directory of Open Access Journals (Sweden)

    Carmen Alvarez-Lorenzo

    2011-12-01

    Full Text Available 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.

  1. Poly(N-isopropylacrylamide)–poly(ferrocenylsilane) dual-responsive hydrogels: synthesis, characterization and antimicrobial applications

    NARCIS (Netherlands)

    Sui, Xiaofeng; Feng, Xueling; Di Luca, Andrea; van Blitterswijk, Clemens; Moroni, Lorenzo; Hempenius, Mark A.; Vancso, Gyula J.

    2013-01-01

    Novel hydrogels composed of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) macromolecules were formed by photopolymerization. PFS chains bearing acrylate side groups were copolymerized with NIPAM and N,N′-methylenebisacrylamide in

  2. Superabsorbent hydrogel composite based on copolymer cellulose/poly (vinyl alcohol)/CNT

    Energy Technology Data Exchange (ETDEWEB)

    Khoerunnisa, Fitri, E-mail: fitri.khoerunnisa@gmail.com; Hendrawan,; Sonjaya, Yaya; Putri, Oceu Dwi [Department of Chemistry, Indonesia University of Education, Setiabudi 229 Bandung, West Java, Indonesia 40154 (Indonesia)

    2016-04-19

    Superabsorbent hydrogels are cross-linked hydrophilic polymers that can absorb and retain a large volume of water, saline solution, or physiological fluids. A distinctive superabsorbent hydrogel composite based on cellulose/ poly (vinyl alcohol)/ carbon nanotubes was successfully synthesized via the graft bio-copolymerization in an aqueous medium with glutaraldehide as a crosslinking agent. The effect of carbon nanotubes (CNT) on water absorption capacity and mechanical properties of superabsorbent composite were particularly investigated. The Fourier transform infrared spectra showed the evidence of copolymerization of hydrogel precursors as well as the interaction of CNT filler with the hydrogel matrices, as indicated by the shifting of peak intensity and position of several functional groups (O-H, C-H sp{sup 3}, C=O, C-N, C-O). The modification of hydrogel surface morphology and porosity owing to CNT insertion was also confirmed by scanning electron microscopy images. The CNT insertion improved the mechanical strength of superabsorbent hydrogel composites. Moreover, insertion of CNT into hydrogel matrix remarkably increased the swelling capacity of superabsorbent composites up to 840%. This huge water absorption capacity of hydrogel composites offers promising applications in development of superabsorbent polymers.

  3. Superabsorbent hydrogel composite based on copolymer cellulose/poly (vinyl alcohol)/CNT

    International Nuclear Information System (INIS)

    Khoerunnisa, Fitri; Hendrawan,; Sonjaya, Yaya; Putri, Oceu Dwi

    2016-01-01

    Superabsorbent hydrogels are cross-linked hydrophilic polymers that can absorb and retain a large volume of water, saline solution, or physiological fluids. A distinctive superabsorbent hydrogel composite based on cellulose/ poly (vinyl alcohol)/ carbon nanotubes was successfully synthesized via the graft bio-copolymerization in an aqueous medium with glutaraldehide as a crosslinking agent. The effect of carbon nanotubes (CNT) on water absorption capacity and mechanical properties of superabsorbent composite were particularly investigated. The Fourier transform infrared spectra showed the evidence of copolymerization of hydrogel precursors as well as the interaction of CNT filler with the hydrogel matrices, as indicated by the shifting of peak intensity and position of several functional groups (O-H, C-H sp"3, C=O, C-N, C-O). The modification of hydrogel surface morphology and porosity owing to CNT insertion was also confirmed by scanning electron microscopy images. The CNT insertion improved the mechanical strength of superabsorbent hydrogel composites. Moreover, insertion of CNT into hydrogel matrix remarkably increased the swelling capacity of superabsorbent composites up to 840%. This huge water absorption capacity of hydrogel composites offers promising applications in development of superabsorbent polymers.

  4. Synthesis and Characterization of PVP-Grafted-Starch Hydrogels Using Gamma Radiation

    International Nuclear Information System (INIS)

    Suwanmala, Phiriyatorn; Hemvichian, Kasinee; Sonsuk, Manit

    2004-10-01

    A Series of hydrogels were prepared from gelatinized cassava starch and vinylpyrrolidone by radiation-induced graft copolymerization. Gel fraction, swelling ratio and gel strength of the obtained hydrogels were characterized. The experimental results show that the swelling ratio is inversely dependent on the radiation dose. The results from PVP-grafted-starch were subsequently compared with those of PVP hydrogels and PVP-blended-starch hydrogels. It was found that the PVP-grafted-starch hydrogels, with gel fraction higher than 80% can be prepared at the dose of 10 kGy, while PVP and PVP-blended-starch hydrogels require at least 30 kGy to obtain gels with more than 80% gel fraction

  5. Co-Deposition of a Hydrogel/Calcium Phosphate Hybrid Layer on 3D Printed Poly(Lactic Acid Scaffolds via Dip Coating: Towards Automated Biomaterials Fabrication

    Directory of Open Access Journals (Sweden)

    Matthias Schneider

    2018-03-01

    Full Text Available The article describes the surface modification of 3D printed poly(lactic acid (PLA scaffolds with calcium phosphate (CP/gelatin and CP/chitosan hybrid coating layers. The presence of gelatin or chitosan significantly enhances CP co-deposition and adhesion of the mineral layer on the PLA scaffolds. The hydrogel/CP coating layers are fairly thick and the mineral is a mixture of brushite, octacalcium phosphate, and hydroxyapatite. Mineral formation is uniform throughout the printed architectures and all steps (printing, hydrogel deposition, and mineralization are in principle amenable to automatization. Overall, the process reported here therefore has a high application potential for the controlled synthesis of biomimetic coatings on polymeric biomaterials.

  6. Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering.

    Science.gov (United States)

    Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Rigogliuso, Salvatrice; Ghersi, Giulio; Giammona, Gaetano

    2013-07-01

    In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Effect of liposomes on rheological and syringeability properties of hyaluronic acid hydrogels intended for local injection of drugs.

    Science.gov (United States)

    El Kechai, Naila; Bochot, Amélie; Huang, Nicolas; Nguyen, Yann; Ferrary, Evelyne; Agnely, Florence

    2015-06-20

    The aim of this work was to thoroughly study the effect of liposomes on the rheological and the syringeability properties of hyaluronic acid (HA) hydrogels intended for the local administration of drugs by injection. Whatever the characteristics of the liposomes added (neutral, positively or negatively charged, with a corona of polyethylene glycol chains, size), the viscosity and the elasticity of HA gels increased in a lipid concentration-dependent manner. Indeed, liposomes strengthened the network formed by HA chains due to their interactions with this polymer. The nature and the resulting effects of these interactions depended on liposome composition and concentration. The highest viscosity and elasticity were observed with liposomes covered by polyethylene glycol chains while neutral liposomes displayed the lowest effect. Despite their high viscosity at rest, all the formulations remained easily injectable through needles commonly used for local injections thanks to the shear-thinning behavior of HA gels. The present study demonstrates that rheological and syringeability tests are both necessary to elucidate the behavior of such systems during and post injection. In conclusion, HA liposomal gels appear to be a promising and versatile formulation platform for a wide range of applications in local drug delivery when an injection is required. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Hyaluronic acid-laminin hydrogels increase neural stem cell transplant retention and migratory response to SDF-1α.

    Science.gov (United States)

    Addington, C P; Dharmawaj, S; Heffernan, J M; Sirianni, R W; Stabenfeldt, S E

    2017-07-01

    The chemokine SDF-1α plays a critical role in mediating stem cell response to injury and disease and has specifically been shown to mobilize neural progenitor/stem cells (NPSCs) towards sites of neural injury. Current neural transplant paradigms within the brain suffer from low rates of retention and engraftment after injury. Therefore, increasing transplant sensitivity to injury-induced SDF-1α represents a method for increasing neural transplant efficacy. Previously, we have reported on a hyaluronic acid-laminin based hydrogel (HA-Lm gel) that increases NPSC expression of SDF-1α receptor, CXCR4, and subsequently, NPSC chemotactic migration towards a source of SDF-1α in vitro. The study presented here investigates the capacity of the HA-Lm gel to promote NPSC response to exogenous SDF-1α in vivo. We observed the HA-Lm gel to significantly increase NPSC transplant retention and migration in response to SDF-1α in a manner critically dependent on signaling via the SDF-1α-CXCR4 axis. This work lays the foundation for development of a more effective cell therapy for neural injury, but also has broader implications in the fields of tissue engineering and regenerative medicine given the essential roles of SDF-1α across injury and disease states. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Influence Of Initiator Types And Emulsion Polymerization Techniques To Particle Size Of Copolymerization Styrene-Butyl Acrylate-Methyl Methacrylate

    Directory of Open Access Journals (Sweden)

    Ariyanti Sarwono

    2008-11-01

    Full Text Available Influence of initiator types and emulsion polymerization techniques to particle size of copolymerization styrene-butyl acrylate-methyl methacrylate. Copoly(styrene/butyl acrylic/methyl methacrylic was prepared by emulsion polymerization method. This paper describes effect of insiator types i.e. ammonium persulfate (APS, hydrogen peroxide, ters-butyl peroxide (TBHP, initiator redox (H2O2/ascorbic acid and polymerization techniques i.e. batch and semicontinue to particle size distribution of copoly(styrene/butyl acrylic/methyl methacrylic. Initiator TBHP and H2O2 could not initiate copolymerization properly, but initiator APS and redox initiate copolymerization with batch and semi continue techniques could well perform. The higher concentration of APS, the greater particle size of the copolymer, but the copolymer is polymodal. Initiator redox (H2O2/ascorbic acid produced greater particle size than initiator redox (ascorbic acid/ H2O2.

  10. Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering

    International Nuclear Information System (INIS)

    Palumbo, Fabio Salvatore; Pitarresi, Giovanna; Fiorica, Calogero; Rigogliuso, Salvatrice; Ghersi, Giulio; Giammona, Gaetano

    2013-01-01

    In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. - Highlights: ► Hyaluronic acid (HA) has been functionalized with ethylenediamine (EDA). ► Amino groups of HA-EDA allow the reaction with α-elastin and ethylene glycol diglycidyl ether (EGDGE). ► Chemical scaffolds of HA-EDA-graft-α-elastin/EGDGE have been characterized. ► The presence of α-elastin affects porosity, swelling and enzymatic degradation of scaffolds. ► The presence of α-elastin improves attachment, viability and proliferation of fibroblasts and smooth muscle cells

  11. Chemical hydrogels based on a hyaluronic acid-graft-α-elastin derivative as potential scaffolds for tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Palumbo, Fabio Salvatore [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); Pitarresi, Giovanna, E-mail: giovanna.pitarresi@unipa.it [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); Institute of Biophysics at Palermo, Italian National Research Council, Via Ugo La Malfa 153, 90146 Palermo (Italy); Fiorica, Calogero [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); Rigogliuso, Salvatrice; Ghersi, Giulio [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Biologia Cellulare, Università degli Studi di Palermo, Viale delle Scienze ed. 16, 90128, Palermo (Italy); Giammona, Gaetano [Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari, Sezione di Chimica e Tecnologie Farmaceutiche, Università degli Studi di Palermo, Via Archirafi 32, 90123, Palermo (Italy); IBIM-CNR, Via Ugo La Malfa 153, 90146 Palermo (Italy)

    2013-07-01

    In this work hyaluronic acid (HA) functionalized with ethylenediamine (EDA) has been employed to graft α-elastin. In particular a HA-EDA derivative bearing 50 mol% of pendant amino groups has been successfully employed to produce the copolymer HA-EDA-g-α-elastin containing 32% w/w of protein. After grafting with α-elastin, remaining free amino groups reacted with ethylene glycol diglycidyl ether (EGDGE) for producing chemical hydrogels, proposed as scaffolds for tissue engineering. Swelling degree, resistance to chemical and enzymatic hydrolysis, as well as preliminary biological properties of HA-EDA-g-α-elastin/EGDGE scaffold have been evaluated and compared with a HA-EDA/EGDGE scaffold. The presence of α-elastin grafted to HA-EDA improves attachment, viability and proliferation of primary rat dermal fibroblasts and human umbilical artery smooth muscle cells. Biological performance of HA-EDA-g-α-elastin/EGDGE scaffold resulted comparable to that of a commercial collagen type I sponge (Antema®), chosen as a positive control. - Highlights: ► Hyaluronic acid (HA) has been functionalized with ethylenediamine (EDA). ► Amino groups of HA-EDA allow the reaction with α-elastin and ethylene glycol diglycidyl ether (EGDGE). ► Chemical scaffolds of HA-EDA-graft-α-elastin/EGDGE have been characterized. ► The presence of α-elastin affects porosity, swelling and enzymatic degradation of scaffolds. ► The presence of α-elastin improves attachment, viability and proliferation of fibroblasts and smooth muscle cells.

  12. A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Hasan, E-mail: samarhass@yahoo.com [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Minami, Hideto [Graduate School of Engineering, Kobe University, Kobe 657-8501 (Japan); Tauer, Klaus [Max Planck Institute of Colloid and Interfaces, Am Mühlenberg, 14476 Golm (Germany); Gafur, Mohammad Abdul [Pilot Plant and Process Development Centre, BCSIR, Dhaka 1205 (Bangladesh); Rahman, Mohammad Mahbubor [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh)

    2016-08-15

    A combination of maghemite polypyrrole (PPy/γ-Fe{sub 2}O{sub 3}) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl{sub 3} as a oxidant and p-toluene sulfonic acid ( p-TSA) as a dopant. In the reaction system FeCl{sub 3} functioned as a source of Fe(III) for the formation of γ-Fe{sub 2}O{sub 3}. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl{sub 2}. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV–visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water. - Highlights: • P(S-NIPAM-MAA-PEGMA) hydrogel particles were prepared. • P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles were prepared. • Oxidative polymerization of pyrrole and precipitation of γ-Fe{sub 2}O{sub 3

  13. Synthesis and Characterization of Super absorbent Hydrogels Based on Natural Polymers Using Ionizing Radiations

    International Nuclear Information System (INIS)

    Deghiedy, N.M.A.

    2010-01-01

    Radiation processing technology is a useful tool for modification of polymer material including grafting of monomer onto polymer. In this study, novel super absorbent hydrogels was prepared with biodegradable and eco-friendly properties by graft copolymerization of chitosan and different synthetic monomers (AAc, DEAEMA, HEMA, HPMA and HEA) using gamma irradiation to examine the potential use of these hydrogels in the controlled drug release systems. The different chitosan hydrogels were characterized using FTIR spectroscopy, scanning electron microscopy and thermal analysis techniques. The effects of the preparation conditions on the gelation process of the synthesized copolymer were investigated. The influence of variables such as feed concentration, irradiation dose, composition ratio, ph and temperature on the swelling of the prepared hydrogels was also examined. The water absorbency of these hydrogels in various ph and salt solutions was studied. The swelling kinetics of the prepared hydrogels and in vitro release dynamics of model drug (Chlortetracycline hydrochloride) from these hydrogels has been studied for the evaluation of swelling mechanism and drug release mechanism from the hydrogels. The adsorption and in vitro release profiles of Chlortetracycline HCl from the prepared gels were also estimated in different ph buffers. The amount of drug released from CS/ (AAc-DEAEMA) hydrogels was higher than that released from other modified CS/AAc hydrogels. This preliminary investigation of chitosan based hydrogels showed that they may be exploited to expand the utilization of these systems in drug delivery applications

  14. Synthesis and Characterization of Chemically Cross-Linked Acrylic Acid/Gelatin Hydrogels: Effect of pH and Composition on Swelling and Drug Release

    Directory of Open Access Journals (Sweden)

    Syed Majid Hanif Bukhari

    2015-01-01

    Full Text Available This present work was aimed at synthesizing pH-sensitive cross-linked AA/Gelatin hydrogels by free radical polymerization. Ammonium persulfate and ethylene glycol dimethacrylate (EGDMA were used as initiator and as cross-linking agent, respectively. Different feed ratios of acrylic acid, gelatin, and EGDMA were used to investigate the effect of monomer, polymer, and degree of cross-linking on swelling and release pattern of the model drug. The swelling behavior of the hydrogel samples was studied in 0.05 M USP phosphate buffer solutions of various pH values pH 1.2, pH 5.5, pH 6.5, and pH 7.5. The prepared samples were evaluated for porosity and sol-gel fraction analysis. Pheniramine maleate used for allergy treatment was loaded as model drug in selected samples. The release study of the drug was investigated in 0.05 M USP phosphate buffer of varying pH values (1.2, 5.5, and 7.5 for 12 hrs. The release data was fitted to various kinetic models to study the release mechanism. Hydrogels were characterized by Fourier transformed infrared (FTIR spectroscopy which confirmed formation of structure. Surface morphology of unloaded and loaded samples was studied by surface electron microscopy (SEM, which confirmed the distribution of model drug in the gel network.

  15. Synthesis of a biocopolymer carrageenan-g-poly(AAm-co-IA/ montmorilonite superabsorbent hydrogel composite

    Directory of Open Access Journals (Sweden)

    M. Sadeghi

    2012-06-01

    Full Text Available A novel superabsorbent hydrogel composite based on kappa-carrageenan (κC has been prepared via graft copolymerization of acrylamide (AAm and itaconic acid (IA monomers in the presence of montmorolonite clay powder, methylenebisacrylamide (MBA as the crosslinking agent and ammonium persulfate (APS as initiator. Evidence of grafting and montmorolonite interaction was obtained by comparison of FTIR and TGA spectra of the initial substrates and the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed montmorolonite-organic polymer linkages. Moreover, the morphology of the samples was examined by scanning electron microscopy (SEM. The swelling of the superabsorbing hydrogels was also examined in solutions with pH values ranging between 1.0 and 13.0. Finally, the swelling behavior of these composite polymers was investigated in various salt solutions. Results indicated that the swelling capacity decreased with an increase in the ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect of monovalent cations, as well as ionic crosslinking for multivalent cations.

  16. Cartilage Repair Using Composites of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Hyaluronic Acid Hydrogel in a Minipig Model.

    Science.gov (United States)

    Ha, Chul-Won; Park, Yong-Beom; Chung, Jun-Young; Park, Yong-Geun

    2015-09-01

    The cartilage regeneration potential of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) with a hyaluronic acid (HA) hydrogel composite has shown remarkable results in rat and rabbit models. The purpose of the present study was to confirm the consistent regenerative potential in a pig model using three different cell lines. A full-thickness chondral injury was intentionally created in the trochlear groove of each knee in 6 minipigs. Three weeks later, an osteochondral defect, 5 mm wide by 10 mm deep, was created, followed by an 8-mm-wide and 5-mm-deep reaming. A mixture (1.5 ml) of hUCB-MSCs (0.5×10(7) cells per milliliter) and 4% HA hydrogel composite was then transplanted into the defect on the right knee. Each cell line was used in two minipigs. The osteochondral defect created in the same manner on the left knee was untreated to act as the control. At 12 weeks postoperatively, the pigs were sacrificed, and the degree of subsequent cartilage regeneration was evaluated by gross and histological analysis. The transplanted knee resulted in superior and more complete hyaline cartilage regeneration compared with the control knee. The cellular characteristics (e.g., cellular proliferation and chondrogenic differentiation capacity) of the hUCB-MSCs influenced the degree of cartilage regeneration potential. This evidence of consistent cartilage regeneration using composites of hUCB-MSCs and HA hydrogel in a large animal model could be a stepping stone to a human clinical trial in the future. To date, several studies have investigated the chondrogenic potential of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs); however, the preclinical studies are still limited in numbers with various results. In parallel, in the past several years, the cartilage regeneration potential of hUCB-MSCs with a hyaluronic acid (HA) hydrogel composite have been investigated and remarkable results in rat and rabbit models have been attained. (These

  17. Fabrication of Novel Hydrogel with Berberine-Enriched Carboxymethylcellulose and Hyaluronic Acid as an Anti-Inflammatory Barrier Membrane

    Directory of Open Access Journals (Sweden)

    Yu-Chih Huang

    2016-01-01

    Full Text Available An antiadhesion barrier membrane is an important biomaterial for protecting tissue from postsurgical complications. However, there is room to improve these membranes. Recently, carboxymethylcellulose (CMC incorporated with hyaluronic acid (HA as an antiadhesion barrier membrane and drug delivery system has been reported to provide excellent tissue regeneration and biocompatibility. The aim of this study was to fabricate a novel hydrogel membrane composed of berberine-enriched CMC prepared from bark of the P. amurense tree and HA (PE-CMC/HA. In vitro anti-inflammatory properties were evaluated to determine possible clinical applications. The PE-CMC/HA membranes were fabricated by mixing PE-CMC and HA as a base with the addition of polyvinyl alcohol to form a film. Tensile strength and ultramorphology of the membrane were evaluated using a universal testing machine and scanning electron microscope, respectively. Berberine content of the membrane was confirmed using a UV-Vis spectrophotometer at a wavelength of 260 nm. Anti-inflammatory property of the membrane was measured using a Griess reaction assay. Our results showed that fabricated PE-CMC/HA releases berberine at a concentration of 660 μg/ml while optimal plasticity was obtained at a 30 : 70 PE-CMC/HA ratio. The berberine-enriched PE-CMC/HA had an inhibited 60% of inflammation stimulated by LPS. These results suggest that the PE-CMC/HA membrane fabricated in this study is a useful anti-inflammatory berberine release system.

  18. Preparation and characterization of pH-sensitive methyl methacrylate-g-starch/hydroxypropylated starch hydrogels: in vitro and in vivo study on release of esomeprazole magnesium.

    Science.gov (United States)

    Kumar, Pankaj; Ganure, Ashok Laxmanrao; Subudhi, Bharat Bhushan; Shukla, Shubhanjali

    2015-06-01

    In the present study, novel hydrogels were prepared through graft copolymerization of methyl methacrylate onto starch and hydroxypropylated starch for intestinal drug delivery. The successful grafting has been confirmed by FTIR, NMR spectroscopy, and elemental analysis. Morphological examination of copolymeric hydrogels by scanning electron microscopy (SEM) confirms the macroporous nature of the copolymers. The high decomposition temperature was observed in thermograms indicating the thermal stability of the hydrogels. To attain a hydrogel with maximum percent graft yield, the impact of reaction variables like concentration of ceric ammonium nitrate as initiator and methyl methacrylate as monomer were consistently optimized. X-ray powder diffraction and differential scanning calorimetric analysis supported the successful entrapment of the drug moiety (esomeprazole magnesium; proton pump inhibitor) within the hydrogel network. Drug encapsulation efficiency of optimized hydrogels was found to be >78%. Furthermore, swelling capacity of copolymeric hydrogels exhibited a pH-responsive behavior which makes the synthesized hydrogels potential candidates for controlled delivery of medicinal agents. In vitro drug release was found to be sustained up to 14 h with 80-90% drug release in pH 6.8 solution; however, the cumulative release was 40-45% in pH 1.2. The gastrointestinal transit behavior of optimized hydrogel was determined by gamma scintigraphy, using (99m)Tc as marker. The amount of radioactive tracer released from the labeled hydrogel was minimal when the hydrogel was in the stomach, whereas it increased as hydrogel reached in intestine. Well-correlated results of in vitro and in vivo analysis proved their controlled release behavior with preferential delivery into alkaline pH environment.

  19. Co-assembly of chitosan and phospholipids into hybrid hydrogels

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Shekarforoush, Elhamalsadat; Engwer, Christoph

    2016-01-01

    Novel hybrid hydrogels were formed by adding chitosan (Ch) to phospholipids (P) self-assembled particles in lactic acid. The effect of the phospholipid concentration on the hydrogel properties was investigated and was observed to affect the rate of hydrogel formation and viscoelastic properties...

  20. A Glycyrrhetinic Acid-Modified Curcumin Supramolecular Hydrogel for liver tumor targeting therapy

    Science.gov (United States)

    Chen, Guoqin; Li, Jinliang; Cai, Yanbin; Zhan, Jie; Gao, Jie; Song, Mingcai; Shi, Yang; Yang, Zhimou

    2017-03-01

    Curcumin (Cur), a phenolic anti-oxidant compound obtained from Curcuma longa plant, possesses a variety of therapeutic properties. However, it is suffered from its low water solubility and low bioavailability property, which seriously restricts its clinical application. In this study, we developed a glycyrrhetinic acid (GA) modified curcumin supramolecular pro-gelator (GA-Cur) and a control compound Nap-Cur by replacing GA with the naphthylacetic acid (Nap). Both compounds showed good water solubility and could form supramolecular gels by disulfide bond reduction triggered by glutathione (GSH) in vitro. Both formed gels could sustainedly release Cur in buffer solutions. We also investigated the cytotoxicity of pro-gelators to HepG2 cells by a MTT assay and determined the cellular uptake behaviours of them by fluorescence microscopy and LC-MS. Due to the over expression of GA receptor in liver cancer cells, our pro-gelator of GA-Cur showed an enhanced cellular uptake and better inhibition capacity to liver tumor cells than Nap-Cur. Therefore, the GA-Cur could significantly inhibit HepG2 cell growth. Our study provides a novel nanomaterial for liver tumor chemotherapy.

  1. Radical Copolymerization Kinetics of Bio-Renewable Butyrolactone Monomer in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Sharmaine B. Luk

    2017-10-01

    Full Text Available The radical copolymerization kinetics of acrylamide (AM and the water-soluble monomer sodium 4-hydroxy-4-methyl-2-methylene butanoate (SHMeMB, formed by saponification of the bio-sourced monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL, are investigated to explain the previously reported slow rates of reaction during synthesis of superabsorbent hydrogels. Limiting conversions were observed to decrease with increased temperature during SHMeMB homopolymerization, suggesting that polymerization rate is limited by depropagation. Comonomer composition drift also increased with temperature, with more AM incorporated into the copolymer due to SHMeMB depropagation. Using previous estimates for the SHMeMB propagation rate coefficient, the conversion profiles were used to estimate rate coefficients for depropagation and termination (kt. The estimate for kt,SHMeMB was found to be of the same order of magnitude as that recently reported for sodium methacrylate, with the averaged copolymerization termination rate coefficient dominated by the presence of SHMeMB in the system. In addition, it was found that depropagation still controlled the SHMeMB polymerization rate at elevated temperatures in the presence of added salt.

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

    Science.gov (United States)

    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.

  3. Release of Water Soluble Drugs from Dynamically Swelling POLY(2-HYDROXYETHYL Methacrylate - CO - Methacrylic Acid) Hydrogels.

    Science.gov (United States)

    Kou, Jim Hwai-Cher

    In this study, ionizable copolymers of HEMA and methacrylic acid (MA) are investigated for their potential use in developing pH dependent oral delivery systems. Because of the MA units, these gels swell extensively at high pH. Since solute diffusion in the hydrophilic polymers depends highly on the water content of the matrix, it is anticipated that the release rate will be modulated by this pH induced swelling. From a practical point of view, the advantage of the present system is that one can minimize drug loss in the stomach and achieve a programmed release in intestine. This approach is expected to improve delivery of acid labile drugs or drugs that cause severe gastrointestinal side effects. This work mainly focuses on the basic understanding of the mechanism involved in drug release from the poly(HEMA -co- MA) gels, especially under dynamic swelling conditions. Equilibrium swelling is first characterized since water content is the major determinant of transport properties in these gels. Phenylpropanolamine (PPA) is chosen as the model drug for the release study and its diffusion characteristics in the gel matrix determined. The data obtained show that the PPA diffusivity follows the free volume theory of Yasuda, which explains the accelerating effect of swelling on drug release. A mathematical model based on a diffusion mechanism has been developed to describe PPA release from the swelling gels. Based on this model, several significant conclusions can be drawn. First, the release rate can be modulated by the aspect ratio of the cylindrical geometry, and this has a practical implication in dosage form design. Second, the release rate can be lowered quite considerably if the dimensional increase due to swelling is significant. Consequently, it is the balance between the drug diffusivity increase and the gel dimensional growth that determines the release rate from the swelling matrix. Third, quasi-steady release kinetics, which are characteristic of swelling

  4. Preparation of poly(acrylic acid)-chitosan hydrogels by gamma irradiation for metal ions sorption

    International Nuclear Information System (INIS)

    Tran Thu Hong; Le Hai; Nguyen Tan Man; Tran Thi Tam; Pham Thi Le Ha; Pham Thi Sam; Nguyen Duy Hang; Le Huu Tu; Le Van Toan

    2013-01-01

    Acid acrylic (AAc) was grafted onto crosslinked chitosan to make Chitosan-g-AAc copolymer with concentration of AAc from 0.5 to 15% by gamma irradiation. The optimal dose for grafting of 15% AAc onto chitosan was 5 kGy. Physical and chemical properties of irradiated samples such as SEM images, FTIR spectroscopy, TGA and swelling behavior at different pHs were evaluated. The grafting yield increased with the increase in dose, it reached 52% at 7 kGy irradiation dose. The application were grafted materials to adsorb metals ion from aqueous solutions was also investigated with both ungrafted and grafted chitosan beads under changing pH from 3 to 6. Grafted chitosan presented higher sorption capacity for most of metal ions than unmodified chitosan. (author)

  5. Swelling characteristics of acrylic acid polyelectrolyte hydrogel in a dc electric field

    Science.gov (United States)

    Jabbari, Esmaiel; Tavakoli, Javad; Sarvestani, Alireza S.

    2007-10-01

    A novel application of environmentally sensitive polyelectrolytes is in the fabrication of BioMEMS devices as sensors and actuators. Poly(acrylic acid) (PAA) gels are anionic polyelectrolyte networks that exhibit volume expansion in aqueous physiological environments. When an electric field is applied to PAA polyelectrolyte gels, the fixed anionic polyelectrolyte charges and the requirement of electro-neutrality in the network generate an osmotic pressure, above that in the absence of the electric field, to expand the network. The objective of this research was to investigate the effect of an externally applied dc electric field on the volume expansion of the PAA polyelectrolyte gel in a simulated physiological solution of phosphate buffer saline (PBS). For swelling studies in the electric field, two platinum-coated plates, as electrodes, were wrapped in a polyethylene sheet to protect the plates from corrosion and placed vertically in a vessel filled with PBS. The plates were placed on a rail such that the distance between the two plates could be adjusted. The PAA gel was synthesized by free radical crosslinking of acrylic acid monomer with ethylene glycol dimethacrylate (EGDMA) crosslinker. Our results demonstrate that volume expansion depends on the intensity of the electric field, the PAA network density, network homogeneity, and the position of the gel in the field relative to positive/negative electrodes. Our model predictions for PAA volume expansion, based on the dilute electrolyte concentration in the gel network, is in excellent agreement with the experimental findings in the high-electric-field regime (250-300 Newton/Coulomb).

  6. Radiation induced graft copolymerization of jute fibre

    International Nuclear Information System (INIS)

    Al-Siddique, F.R.; Khan, A.U.; Sheikh, R.A.

    1983-01-01

    Graft copolymerized jute fibres (GCJF) were prepared by γ-ray induced graft copolymerization of various monomers onto bleached and de-waxed jute samples. The effect of γ-ray dose on the tendency of various monomers to form graft co-polymer was studied. It was found that the tendency decreases as follows: methylmethacrylate (MMA)>acrylonitrile (AN)>styrene (STY)>vinylacetate (VA). When the effect of monomer concentration on the formation of graft co-polymer was studied, it was found that a mixture of AN and STY gave a higher amount of grafting than what was observed for STY or AN alone, when used at a comparable concentration. A study on the effect of concentration of methyl alcohol (a swelling agent for jute) on the tendency of the monomers to form graft co-polymer showed that although there is no effect when only AN is used, an appreciable effect is observed if AN is mixed with STY. In the later case the tendency of graft co-polymerization increases with the increase of CH 3 OH concentration. It was further observed that the increase of CH 3 OH also has a positive influence on MMA to form graft co-polymer in the range of 40-90% CH 3 OH. The affinity of GCJF towards moisture has been found to decrease with the increase of polymer loading onto jute. The presence of swelling agents during graft copolymer formation was also found to decrease the affinity of GCJF towards moisture. (author)

  7. Hydrogel based occlusion systems

    NARCIS (Netherlands)

    Stam, F.A.; Jackson, N.; Dubruel, P.; Adesanya, K.; Embrechts, A.; Mendes, E.; Neves, H.P.; Herijgers, P.; Verbrugghe, Y.; Shacham, Y.; Engel, L.; Krylov, V.

    2013-01-01

    A hydrogel based occlusion system, a method for occluding vessels, appendages or aneurysms, and a method for hydrogel synthesis are disclosed. The hydrogel based occlusion system includes a hydrogel having a shrunken and a swollen state and a delivery tool configured to deliver the hydrogel to a

  8. Gum ghatti and poly(acrylamide-co-acrylic acid) based biodegradable hydrogel-evaluation of the flocculation and adsorption properties

    CSIR Research Space (South Africa)

    Mittal, H

    2015-10-01

    Full Text Available removal of cationic dyes from the aqueous solutions and it was found to adsorb 96% of malachite green and 99% of methyl violet. Finally, the hydrogel polymer was subjected to biodegradation using the composting method and 91.77% degradation was achieved...

  9. Complex-radical copolymerization of vinyl monomers on organoelemental initiators

    International Nuclear Information System (INIS)

    Grishin, D.F.

    1993-01-01

    Data on regularities of the initiation and growth of the (co)polymerization of polar vinyl series monomers on organo-elemental initiator, organo-boron in particular, are generalized. The effect of organo-metallic compounds and some phenol type inhibitors on the rate of acrylate (co)polymerization is analyzed from view of the change of electroacceptor properties (electrophilicity) of macroradicals

  10. Mathematical Simulation of High-Conversion Binary Copolymerization

    Institute of Scientific and Technical Information of China (English)

    JiangWei; QinJiguang

    2005-01-01

    A new model for mathematical simulation of high-conversion binary copolymerization was established by combination of the concept of the three stage polymerization model (TSPM) proposed by Qin et al. for bulk free radical homopolymerization with the North equation to describe high-conversion copolymerization reaction exhibiting a strong gel effect, and the mathematical expressions of this new model were derived. Like TSPM, the new model also assmnes that the whole course of binary copolymerization can be divided into three different stages: low conversion, gel effect and glass effect stages. In addition, the reaction rate constants and the initiator efficiency at each copolymerization stage do not vary with conversion. Based on the expressions derived, a plot method for determining the overall rate constants and critical conversions was proposed. The literature data on conversion history for styrene (St)-methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA)-MMA copolymerizations were treated to examine the model, which shows that the model is satisfactory.

  11. Alternating copolymerization of fluoroalkenes with carbon monoxide.

    Science.gov (United States)

    Fujita, Tomoyuki; Nakano, Koji; Yamashita, Makoto; Nozaki, Kyoko

    2006-02-15

    The palladium-catalyzed alternating copolymerization of fluoroalkenes, represented as CH(2)=CH-CH(2)-C(n)F(2n+1), with CO was performed using (R,S)-BINAPHOS (2e) as a ligand. The CH(2)-C(n)F(2n+1) group is the most electronegative substituent ever reported for the copolymerization (Taft's sigma value of 0.90 for CH(2)CF(3)). The copolymer obtained from CH(2)=CH-CH(2)-C(8)F(17) (1a) existed as a mixture of polyspiroketal and polyketone, while that from CH(2)=CH-CH(2)-C(4)F(9) (1b) was a pure polyspiroketal, as was revealed by infrared and (13)C-CP/MAS NMR spectroscopies. The terminal structure of the polymer from 1b was confirmed by MALDI-TOF MS spectrometry. Detailed NMR studies suggested that the much higher reactivity with (R,S)-BINAPHOS (2e) than that with the conventional ligand DPPP (2a) can be attributed to the unique 1,2-insertion of the fluoroalkene into acylpalladium species. The existence of an electronegative substituent on the alpha-carbon of the palladium center is successfully avoided in the 1,2-insertion mechanism.

  12. Graft-copolymerization onto carbon black

    International Nuclear Information System (INIS)

    Nakase, Yoshiaki; Nishii, Masanobu; Kijima, Toshiyuki; Kato, Hiroshi.

    1988-07-01

    Radiation-induced graft copolymerization of vinyl monomer onto carbon black was performed. During the γ-ray- and electron beam-induced polymerization (In-source), or the electron beam post-polymerization, the graft-copolymerization behavior was affected by the kinds of both carbon blacks and monomers, i.e. the smaller the size of carbon black particles, the higher the apparent grafted fraction. Homopolymer in the grafted carbon black samples was washed out by the solvent of the polymer, and the extracted polymer seemed to be dimer or trimer of the used monomer. In the case of the post-polymerization with the pre-irradiation doses of 50 Mrad, homopolymer was hardly observed. The polymer sheets of plastics or rubbers with grafted carbon black had an electrical conductivity unalterable considerably by the heating cycles. The particles of grafted carbon black in the sheet might be kept much more at the surface layer within 100 nm depth than at the inner layer. (author)

  13. Smart hydrogel functional materials

    CERN Document Server

    Chu, Liang-Yin; Ju, Xiao-Jie

    2014-01-01

    This book systematically introduces smart hydrogel functional materials with the configurations ranging from hydrogels to microgels. It serves as an excellent reference for designing and fabricating artificial smart hydrogel functional materials.

  14. Crosslinking of poly(vinylpyrrolidone)/acrylic acid with tragacanth gum for hydrogels formation for use in drug delivery applications.

    Science.gov (United States)

    Singh, Baljit; Sharma, Vikrant

    2017-02-10

    Tragacanth gum (TG) is generally recognized as safe by the Food and Drug Administration. The present article discusses the design of ciprofloxacin loaded TG based hydrogels for use in drug delivery especially to improve the pharmacotherapy of diverticulitis. The polymers were characterized by SEMs, FTIR, 13 C NMR, XRD, TGA, DSC, gel strength and swelling studies. The polymer network parameters, mucoadhesion, gel strength, drug release mechanism and kinetic model were also determined. The release of drug occurred through non-Fickian diffusion mechanism and best fitted in the Korsmeyer-Peppas model. The pH of the swelling medium has also exerted a strong effect on polymer network structure and mechanical strength. These hydrogels have been observed pH responsive and mucoadhesive in nature and could be utilized for site specific drug delivery. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Preparation of RGO/Fe{sub 3}O{sub 4}/poly (acrylic acid) hydrogel nanocomposites with improved magnetic, thermal and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Didehban, K.H., E-mail: Didehban95@gmail.com; Mohammadi, L.; Azimvand, J.

    2017-07-01

    A hydrogel nanocomposite composed of reduced graphene oxide (RGO), iron oxide (Fe{sub 3}O{sub 4}) nanoparticles, and polyacrylic acid (PAA) was prepared using radical polymerization. Different percentages of RGO, Fe{sub 3}O{sub 4}, and PAA were used to prepare the nanocomposite. Fourier transform infrared spectroscopy (FTIR) results confirmed the formation of the nanocomposite’s chemical structure. X-ray power diffraction (XRD) patterns revealed the principal peak’s 2θ value to be 77.39° with the size of the nanocomposite particles estimated at 96 nm. Results indicated that the electrochemical capacity of the nanocomposites was controlled by the weight percentage of RGO. Increases to the potential scan rate reduced porosity and surface area, thereby decreasing the electrochemical capacity of the nanocomposites. Moreover, increasing the percentage of Fe{sub 3}O{sub 4} nanoparticles in the nanocomposites improved their magnetic characteristics and thermal properties. The latter also improved when the RGO percentage increased. - Highlights: • A hydrogel nanocomposite composed of RGO/Fe{sub 3}O{sub 4}/PAA was synthesized successfully. • Increasing the percentage of iron nanoparticles improved magnetic properties. • Increasing the percentage of RGO improved thermal and electrochemical capacity. • The Fe{sub 3}O{sub 4} nanoparticles directly affected magnetic properties.

  16. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Sari Fouad

    2012-12-01

    Full Text Available We reported in this work that the cationic copolymerization in one step takes place between carbon–carbon double-bond monomer styrene with cyclic monomer tetrahydrofuran. The comonomers studied belong to different families: vinylic and cyclic ether. The reaction is initiated with maghnite-H+ an acid exchanged montmorillonite as acid solid ecocatalyst. Maghnite-H+ is already used as catalyst for polymerization of many vinylic and heterocyclic monomers. The oxonium ion of tetrahydrofuran and carbonium ion of styrene propagated the reaction of copolymerization. The acetic anhydride is essential for the maintenance of the ring opening of tetrahydrofuran and the entry in copolymerization. The temperature was kept constant at 40°C in oil bath heating for 6 hours. A typical reaction product was analyzed by 1H-NMR, 13C-NMR and IR and the formation of the copolymer was confirmed. The reaction was proved by matched with analysis. The maghnite-H+ allowed us to obtain extremely pure copolymer in good yield by following a simples operational conditions. Copyright © 2012 by BCREC UNDIP. All rights reservedReceived: 29th October 2012; Revised: 29th November 2012; Accepted: 29th November 2012[How to Cite: S. Fouad, M.I. Ferrahi, M. Belbachir. (2012. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran. Bulletin of Chemical Reaction Engineering & Catalysis, 7(2: 165-171. (doi:10.9767/bcrec.7.2.4074.165-171][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.4074.165-171 ] | View in 

  17. Preparation and swelling properties of pH-sensitive composite hydrogel beads based on chitosan-g-poly (acrylic acid)/vermiculite and sodium alginate for diclofenac controlled release.

    Science.gov (United States)

    Wang, Qin; Xie, Xiaoling; Zhang, Xiaowei; Zhang, Junping; Wang, Aiqin

    2010-04-01

    A series of pH-sensitive composite hydrogel beads, chitosan-g-poly (acrylic acid)/vermiculite/sodium alginate (CTS-g-PAA/VMT/SA), was prepared using CTS-g-PAA/VMT composite and SA by Ca(2+) as the crosslinking agent. The structure and morphologies of the developed composite hydrogel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling properties and pH-sensitivity of the beads were investigated. In addition, the drug loading and controlled release behaviors of the beads were also evaluated using diclofenac sodium (DS) as the model drug in stimulated gastric fluids (pH 2.1) and intestinal fluids (pH 6.8). The results indicate that the composite hydrogel beads showed good pH-sensitivity. The release rate of the drug from the composite hydrogel beads is remarkably slowed down, which indicated that incorporating VMT into the composite hydrogel beads can improve the burst release effect of the drug. Copyright 2010 Elsevier B.V. All rights reserved.

  18. Logarithmic Exchange Kinetics in Monodisperse Copolymeric Micelles

    Science.gov (United States)

    García Daza, Fabián A.; Bonet Avalos, Josep; Mackie, Allan D.

    2017-06-01

    Experimental measurements of the relaxation kinetics of copolymeric surfactant exchange for micellar systems unexpectedly show a peculiar logarithmic decay. Several authors use polydispersity as an explanation for this behavior. However, in coarse-grained simulations that preserve microscopic details of the surfactants, we find evidence of the same logarithmic behavior. Since we use a strictly monodisperse distribution of chain lengths such a relaxation process cannot be attributed to polydispersity, but has to be caused by an inherent physical process characteristic of this type of system. This is supported by the fact that the decay is specifically logarithmic and not a power law with an exponent inherited from the particular polydispersity distribution of the sample. We suggest that the degeneracy of the energy states of the hydrophobic block in the core, which is broken on leaving the micelle, can qualitatively explain the broad distribution of energy barriers, which gives rise to the observed nonexponential relaxation.

  19. Kinetics and thermodynamics of living copolymerization processes.

    Science.gov (United States)

    Gaspard, Pierre

    2016-11-13

    Theoretical advances are reported on the kinetics and thermodynamics of free and template-directed living copolymerizations. Until recently, the kinetic theory of these processes had only been established in the fully irreversible regime, in which the attachment rates are only considered. However, the entropy production is infinite in this regime and the approach to thermodynamic equilibrium cannot be investigated. For this purpose, the detachment rates should also be included. Inspite of this complication, the kinetics can be exactly solved in the regimes of steady growth and depolymerization. In this way, analytical expressions are obtained for the mean growth velocity, the statistical properties of the copolymer sequences, as well as the thermodynamic entropy production. The results apply to DNA replication, transcription and translation, allowing us to understand important aspects of molecular evolution.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'. © 2016 The Author(s).

  20. Functional and in vitro gastric digestibility of the whey protein hydrogel loaded with nanostructured lipid carriers and gelled via citric acid-mediated crosslinking.

    Science.gov (United States)

    Hashemi, Behnaz; Madadlou, Ashkan; Salami, Maryam

    2017-12-15

    Nanostructured lipid carriers (NLCs) with mean size of 347nm were fabricated and added into a heat-denatured whey protein solution. The subsequent crosslinking of proteins by citric acid or CaCl 2 resulted in the formation of cold-set hydrogels. Fourier transform infrared spectroscopy (FTIR) proposed formation of more hydrogen bonds in gel due to NLC loading or citric acid-mediated gelation. It was also found based on FITR spectroscopy that citric acid crosslinking disordered whey proteins. Scanning electron microscopy (SEM) imaging showed a non-porous and finely meshed microstructure for the crosslinked gels compared to non-crosslinked counterparts. Crosslinking also increased the firmness and water-holding capacity of gels. In pepsin-free fluid, a strong correlation existed between reduction in gel swellability and digestibility over periods up to 60min due to NLC loading and citric acid gelation. However, in peptic fluid, NLC loading and citric acid crosslinking brought about much higher decrease in digestibility than swellability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Free-Radical Copolymerization of Difurylmethane with Maleic

    African Journals Online (AJOL)

    Prof. Jo Michael

    Reaction feeds containing 85 mol % and higher of difurylmethane ... Keywords: difurylmethane; maleic anhydride; copolymerization; thermodecomposition ... delivery apparatus set at 500 psi for a flow rate of 1 cm3 min-1; a Waters model U6K.

  2. Alternating copolymerization of epoxides with anhydrides initiated by organic bases

    Czech Academy of Sciences Publication Activity Database

    Hošťálek, Z.; Trhlíková, Olga; Walterová, Zuzana; Martinez, T.; Peruch, F.; Cramail, H.; Merna, J.

    2017-01-01

    Roč. 88, March (2017), s. 433-447 ISSN 0014-3057 Institutional support: RVO:61389013 Keywords : copolymerization * epoxides * anhydrides Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 3.531, year: 2016

  3. Hydrogels of polyvinylpyrrolidone (PVP) and poly(acrylic acid) (PAA) synthesized by radiation-induced crosslinking of homopolymers

    Science.gov (United States)

    Kadłubowski, Sławomir; Henke, Artur; Ulański, Piotr; Rosiak, Janusz M.

    2010-03-01

    pH-sensitive PVP-PAA hydrogels have been prepared by electron-beam-induced irradiation at pH close to pKa of carboxylic groups. Protonation of these groups promoted the formation of hydrogen bonds between the PAA and PVP segments within the crosslinked structure and caused interpolymer complex formation. To demonstrate possible future application of such gels, we tested them as simple chemical detectors. When loaded with glucose oxidase, the PAA-PVP gel's turbidity and shrinkage was triggered by the presence of glucose due to a drop in pH caused by the enzymatic reaction.

  4. Influence of Irradiated Chitosan on Growth and Flower Quality of Gladiolus at Different Sowing Dates and Synthesis of Radiation Cross-Linked Poly(Acrylic Acid) Hydrogel for Agriculture Applications. Chapter 14

    Energy Technology Data Exchange (ETDEWEB)

    Habib, U.; Ahmed, N. [Department of Horticulture, PMAS Arid Agriculture University, Rawalpindi (Pakistan); Zahid, S.; Yashin, T., E-mail: yasintariq@yahoo.com [Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan)

    2014-07-15

    The plant growth promoter activity of irradiated chitosan on Gladiolus hortulanus cv. Amsterdam was studied. Chitosan was applied in the form of foliar spray at third leaf stage. Corms were sown at three different dates with 15-day intervals. Data on several parameters such as survival percentage, leaf area, plant height, number of florets per spike, and vase life were collected. Chitosan-treated plants showed superior results as compared to the control samples. Acrylic acid-based superabsorbent hydrogel was prepared using phenyltriethoxysilane (PTES) as cross-linker. Different amounts of PTES were incorporated and irradiated at different doses of up to a maximum of 30 kGy. The cross-linked acrylic acid showed hydrogel properties, and its swelling kinetics, gel fraction, and equilibrium degree of swelling (EDS) were studied. The swelling of hydrogel was also affected by pH, ionic strength, and temperature. These hydrogels can be further explored as a super water absorbent material in semi-arid and drought prone areas. (author)

  5. Biomolecule-Responsive Hydrogels in Medicine.

    Science.gov (United States)

    Sharifzadeh, Ghorbanali; Hosseinkhani, Hossein

    2017-12-01

    Recent advances and applications of biomolecule-responsive hydrogels, namely, glucose-responsive hydrogels, protein-responsive hydrogels, and nucleic-acid-responsive hydrogels are highlighted. However, achieving the ultimate purpose of using biomolecule-responsive hydrogels in preclinical and clinical areas is still at the very early stage and calls for more novel designing concepts and advance ideas. On the way toward the real/clinical application of biomolecule-responsive hydrogels, plenty of factors should be extensively studied and examined under both in vitro and in vivo conditions. For example, biocompatibility, biointegration, and toxicity of biomolecule-responsive hydrogels should be carefully evaluated. From the living body's point of view, biocompatibility is seriously depended on the interactions at the tissue/polymer interface. These interactions are influenced by physical nature, chemical structure, surface properties, and degradation of the materials. In addition, the developments of advanced hydrogels with tunable biological and mechanical properties which cause no/low side effects are of great importance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Immobilization of yeast cells on hydrogel carriers obtained by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Luzhao Xin; Carenza, M.; Kaetsu, Isao; Kumakura, Minoru; Yoshida, Masaru; Fujimura, Takashi

    1992-01-01

    Polymer hydrogels were obtained by radiation-induced copolymerization at -78 o C of aqueous solutions of acrylic and methacrylic esters. The matrices were characterized by equilibrium water content measurements, by optical microscopy observations and by scanning electron microscopy analysis. Yeast cells were immobilized on these hydrogels and the ethanol productivity by batch fermentation was determined. Matrix hydrophilicity and porosity were found to deeply influence the adhesion of yeast cells and, hence, the ethanol productivity. The latter as well as other physico-chemical properties were also affected by the presence of a crosslinking agent added in small amounts to the polymerizating mixture. (author)

  7. UV-initiated template copolymerization of AM and MAPTAC: Microblock structure, copolymerization mechanism, and flocculation performance.

    Science.gov (United States)

    Li, Xiang; Zheng, Huaili; Gao, Baoyu; Sun, Yongjun; Liu, Bingzhi; Zhao, Chuanliang

    2017-01-01

    Flocculation as the core technology of sludge pretreatment can improve the dewatering performance of sludge that enables to reduce the cost of sludge transportation and the subsequent disposal costs. Therefore, synthesis of high-efficiency and economic flocculant is remarkably desired in this field. This study presents a cationic polyacrylamide (CPAM) flocculant with microblock structure synthesized through ultraviolet (UV)-initiated template copolymerization by using acrylamide (AM) and methacrylamido propyl trimethyl ammonium chloride (MAPTAC) as monomers, sodium polyacrylate (PAAS) as template, and 2,2'-azobis [2-(2-imidazolin-2-yl) propane] dihydrochloride (VA-044) as photoinitiator. The microblock structure of the CPAM was observed through nuclear magnetic resonance ( 1 H NMR and 13 C NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) analyses. Furthermore, thermogravimetric/differential scanning calorimetry (TG/DSC) analysis was used to evaluate its thermal decomposition property. The copolymerization mechanism was investigated through the determination of the binding constant M K and study on polymerization kinetics. Results showed that the copolymerization was conducted in accordance with the I (ZIP) template polymerization mechanism, and revealed the coexistence of bimolecular termination free-radical reaction and mono-radical termination in the polymerization process. Results of sludge dewatering tests indicated the superior flocculation performance of microblock flocculant than random distributed CPAM. The residual turbidity, filter cake moisture content, and specific resistance to filtration reached 9.37 NTU, 68.01%, and 6.24 (10 12  m kg -1 ), respectively, at 40 mg L -1 of template poly(AM-MAPTAC) and pH 6.0. Furthermore, all flocculant except commercial CPAM showed a wide scope of pH application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Improved homopolymer separation to enable the application of H-1 NMR and HPLC for the determination of the reaction parameters of the graft copolymerization of acrylic acid onto starch

    NARCIS (Netherlands)

    Witono, Judy R.; Marsman, Jan Henk; Noordergraaf, Inge-Willem; Heeres, Hero J.; Janssen, Leon P. B. M.

    2013-01-01

    Graft copolymers of starch with acrylic acid are a promising green, bio based material with many potential applications. The grafting of acrylic acid onto cassava starch in an aqueous medium initiated by Fenton's reagent has been studied. Common grafting result parameters are add-on (yield) and

  9. Tubular scaffolds of gelatin and poly(ε-caprolactone)-block-poly(γ-glutamic acid) blending hydrogel for the proliferation of the primary intestinal smooth muscle cells of rats

    International Nuclear Information System (INIS)

    Jwo, Shyh-Chuan; Chiu, Chu-Hua; Hsieh, Ming-Fa; Tang, Shye-Jye

    2013-01-01

    The proper regeneration of intestinal muscle for functional peristalsis is the most challenging aspect of current small intestine tissue engineering. This study aimed to fabricate a hydrogel scaffold for the proliferation of intestinal smooth muscle cells (ISMCs). Tubular porous scaffolds of 10–20 wt% gelatin and 0.05–0.1 wt% poly(ε-caprolactone)-block-poly(γ-glutamic acid) blending hydrogel were cross-linked by carbodiimide and succinimide in an annular space of a glass mold. The scaffolds with higher gelatin contents degraded slower in the phosphate buffer solution. In rheological measurements, the hydrated scaffolds were elastic (all tangent delta <0.45); they responded differentially to frequency, indicating a complete viscoelastic property that is beneficial for soft tissue regeneration. Isolated rat ISMCs, with the characteristic biomarkers α-SMA, calponin and myh11, were loaded into the scaffolds by using either static or centrifugal methods. The average cell density inside the scaffolds increased in a time-dependent manner in most scaffolds of both seeding groups, although at early time points (seven days) the centrifugal seeding method trapped cells more efficiently and yielded a higher cell density than the static seeding method. The static seeding method increased the cell density from 7.5-fold to 16.3-fold after 28 days, whereas the centrifugal procedure produced a maximum increase of only 2.4-fold in the same period. In vitro degradation data showed that 50–80% of the scaffold was degraded by the 14th day. However, the self-secreted extracellular matrix maintained the integrity of the scaffolds for cell proliferation and spreading for up to 28 days. Confocal microscopic images revealed cell–cell contacts with the formation of a 3D network, demonstrating that the fabricated scaffolds were highly biocompatible. Therefore, these polymeric biomaterials hold great promise for in vivo applications of intestinal tissue engineering. (paper)

  10. Peptide based hydrogels for bone tissue engineering

    International Nuclear Information System (INIS)

    Ranny, H.R.; Schneider, J.P.

    2007-01-01

    Peptide hydrogels are potentially ideal scaffolds for tissue repair and regeneration due to their ability to mimic natural extra cellular matrix. The 20 amino acid peptide HPL8 (H2N- VKVKVKVKVDPP TKVKVKVKV-CONH2), has been shown to fold and self-assemble into a rigid hydrogel based on Environmental cues such as pH, salt, and temperature. Due to its environmental responsiveness, hydrogel assembly can be induced by cell culture media, allowing for 3D encapsulation of osteogenic cells. Initially, 20 cultures of MC3T3 cells proved that the hydrogel is nontoxic and sustains cellular attachment in the absence of serum proteins without altering the physical properties of the hydrogel. The cell-material structure relationship in normal and pathological conditions was further investigated by 3D encapsulation. Cell were viable for 3 weeks and grew in clonogenic spheroids. Characterization of the proliferation, differentiation and constitutive expression of various osteoblastic markers was performed using spectrophotometric methods. The well-defined, fibrillar nanostructure of the hydrogel directs the attachment and attachment and growth of osteoblast cells and dictates the mineralization of hydroxyapatite in a manner similar to bone. This study will enable control over the interaction of cellular systems with the peptide hydrogel with designs for biomedical applications of bone repair. (author)

  11. Manufacturing of hydrogel biomaterials with controlled mechanical properties for tissue engineering applications.

    Science.gov (United States)

    Vedadghavami, Armin; Minooei, Farnaz; Mohammadi, Mohammad Hossein; Khetani, Sultan; Rezaei Kolahchi, Ahmad; Mashayekhan, Shohreh; Sanati-Nezhad, Amir

    2017-10-15

    Hydrogels have been recognized as crucial biomaterials in the field of tissue engineering, regenerative medicine, and drug delivery applications due to their specific characteristics. These biomaterials benefit from retaining a large amount of water, effective mass transfer, similarity to natural tissues and the ability to form different shapes. However, having relatively poor mechanical properties is a limiting factor associated with hydrogel biomaterials. Controlling the biomechanical properties of hydrogels is of paramount importance. In this work, firstly, mechanical characteristics of hydrogels and methods employed for characterizing these properties are explored. Subsequently, the most common approaches used for tuning mechanical properties of hydrogels including but are not limited to, interpenetrating polymer networks, nanocomposites, self-assembly techniques, and co-polymerization are discussed. The performance of different techniques used for tuning biomechanical properties of hydrogels is further compared. Such techniques involve lithography techniques for replication of tissues with complex mechanical profiles; microfluidic techniques applicable for generating gradients of mechanical properties in hydrogel biomaterials for engineering complex human tissues like intervertebral discs, osteochondral tissues, blood vessels and skin layers; and electrospinning techniques for synthesis of hybrid hydrogels and highly ordered fibers with tunable mechanical and biological properties. We finally discuss future perspectives and challenges for controlling biomimetic hydrogel materials possessing proper biomechanical properties. Hydrogels biomaterials are essential constituting components of engineered tissues with the applications in regenerative medicine and drug delivery. The mechanical properties of hydrogels play crucial roles in regulating the interactions between cells and extracellular matrix and directing the cells phenotype and genotype. Despite

  12. Analytical advantages of copolymeric microspheres for fluorimetric sensing - tuneable sensitivity sensors and titration agents.

    Science.gov (United States)

    Stelmach, Emilia; Maksymiuk, Krzysztof; Michalska, Agata

    2017-01-15

    Analytical benefits related to application of copolymeric microspheres containing different number of carboxylic acid mers have been studied on example of acrylate copolymers. These structures can be used as a reagent in heterogeneous pH titration, benefiting from different number of reactive groups - i.e. different concentration of a titrant - within the series of copolymers. Thus introducing the same amount of different microspheres from a series to the sample, different amount of the titrant is introduced. Copolymeric microspheres also can be used as optical sensors - in this respect the increasing number of reactive groups in the series is useful to improve the analytical performance of microprobes - sensitivity of determination or/and response range. The increase in ion-permeability of the spheres with increasing number of reactive mers is advantageous. It is shown that for pH sensitive microspheres containing higher number of carboxyl groups the higher sensitivity for alkaline pH samples is observed for an indicator present in the beads. The significant increase of optical responses is related to enhanced ion transport within the microspheres. For zinc or potassium ions model sensors tested it was shown that by choice of pH conditions and type of microspheres from the series, the optical responses can be tuned - to enhance sensitivity for analyte concentration change as well as to change the response pattern from sigmoidal (higher sensitivity, narrow range) to linear (broader response range). For classical optode systems (e.g. microspheres containing an optical transducer - pH sensitive dye and optically silent ionophore - receptor) copolymeric microspheres containing carboxylic acid mers in their structure allow application of the sensor in alkaline pH range, which is usually inaccessible for applied optical transducer. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Cation-exchanger fabric prepared by electron beam - induced graft copolymerization of binary monomer mixture

    International Nuclear Information System (INIS)

    Bondar, Yu.V.; Kim, H.J.; Lim, Y.J.; Perelygin, V.P.

    2004-01-01

    Applying the electron-beam preirradiation method in air the sorption-active polypropylene fiber, containing sulfonic acid (R-SO 3 H) groups, was prepared by simultaneous graft copolymerization of sodium styrenesulfonate with acrylic acid in water solution. The effect of reaction conditions on the grafting yield and reaction mechanism was examined. It was found that the received CEF contains groups of strong acid (R-SO 3 H) and weak acid (R-COOH) in almost equal proportion. The ion-exchange properties of the CEF towards Cu(II) and Co(II) ions were investigated depending on the form of the CEF and a pH of the solution. It was shown that the utilization of the CEF in Na- form allows to make the best use of its ion-exchange capacity. (author)

  14. Polyvinyl alcohol hydrogels for iontohporesis

    Science.gov (United States)

    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.

  15. Radiation preparation of drug carriers based on poly(N-isopropylacrylamide) hydrogels, their loading capacities and controlled release rates for dexamethasone and tegafur

    International Nuclear Information System (INIS)

    Hoang Dang Sang; Nguyen Van Binh; Tran Bang Diep; Nguyen Thi Thom; Hoang Phuong Thao; Pham Duy Duong; Tran Minh Quynh

    2015-01-01

    Thermo-sensitive hydrogels have great potential in some applications. In order to use as the drug delivery systems, the hydrogels should be biocompatibility. New polymers with more biocompatibility and better biodegradability, and environmental friendly crosslinking agents would be necessary for the successful drug carriers. Poly (N-isopropylacrylamide-co-dimethylacrylamide) based hydrogels have been prepared from the admixture solutions of N-isopropylacrylamide (NIPA) and N,N’-dimethyl acrylamide (DMA) by radiation copolymerization and crosslinking at radiation dose of 20 kGy as reported in our previous study. Water swelling behaviour of the resulting hydrogels were much depended on their nature such as initial ratio of NIPA and DMA. The drug-loaded hydrogels were prepared by merging hydrogel in the solutions containing corresponding drugs. Loading capacity of the hydrogels were about 48.6 and 95.7 mg per g dried hydrogel for dexamethasone and tegafur. The release studies showed that the presence of ions in simulated body fluid and temperature of the solution much affecting to in vitro release behaviors of hydrogels for dexamethasone and tegafur. The release rates were fast for both drug models. The result also revealed that these drug carriers were biocompatibility without skin irritation, suggested the drug-loaded hydrogels may be used as controlled release drug delivery systems. (author)

  16. Recent progress on the design and applications of polysaccharide-based graft copolymer hydrogels as adsorbents for wastewater purification

    CSIR Research Space (South Africa)

    Mittal, Hemant

    2016-05-01

    Full Text Available as emulsifiers and thickeners. In their natural form, gum polysaccharides have poor mechanical and physical properties; therefore, they are frequently modified with various synthetic monomers such as acrylamide and acrylic acid using graft copolymerization. Graft...

  17. Stress relaxing hyaluronic acid-collagen hydrogels promote cell spreading, fiber remodeling, and focal adhesion formation in 3D cell culture.

    Science.gov (United States)

    Lou, Junzhe; Stowers, Ryan; Nam, Sungmin; Xia, Yan; Chaudhuri, Ovijit

    2018-02-01

    The physical and architectural cues of the extracellular matrix (ECM) play a critical role in regulating important cellular functions such as spreading, migration, proliferation, and differentiation. Natural ECM is a complex viscoelastic scaffold composed of various distinct components that are often organized into a fibrillar microstructure. Hydrogels are frequently used as synthetic ECMs for 3D cell culture, but are typically elastic, due to covalent crosslinking, and non-fibrillar. Recent work has revealed the importance of stress relaxation in viscoelastic hydrogels in regulating biological processes such as spreading and differentiation, but these studies all utilize synthetic ECM hydrogels that are non-fibrillar. Key mechanotransduction events, such as focal adhesion formation, have only been observed in fibrillar networks in 3D culture to date. Here we present an interpenetrating network (IPN) hydrogel system based on HA crosslinked with dynamic covalent bonds and collagen I that captures the viscoelasticity and fibrillarity of ECM in tissues. The IPN hydrogels exhibit two distinct processes in stress relaxation, one from collagen and the other from HA crosslinking dynamics. Stress relaxation in the IPN hydrogels can be tuned by modulating HA crosslinker affinity, molecular weight of the HA, or HA concentration. Faster relaxation in the IPN hydrogels promotes cell spreading, fiber remodeling, and focal adhesion (FA) formation - behaviors often inhibited in other hydrogel-based materials in 3D culture. This study presents a new, broadly adaptable materials platform for mimicking key ECM features of viscoelasticity and fibrillarity in hydrogels for 3D cell culture and sheds light on how these mechanical and structural cues regulate cell behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. PVA/atapulgite hydrogels; Hidrogeis de PVA/atapulgita

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, R.N.; Soares, G.A., E-mail: nunes@metalmat.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Paranhos, C.M. [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil); Barreto, L.S. [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil)

    2010-07-01

    PVA hydrogels can be used as wound-healing as a consequence of their biocompatibility, flexibility, etc. In order to improve mechanical resistance of wound-healing, polymeric hydrogels reinforced with clay have been studied. Among national clays, attapulgite stands out. Once it is a natural material, acid treatment can be required in order to remove impurities. In the present work, PVA hydrogels reinforced with attapulgite were produced and they were characterized by swelling behavior, XRD, DSC and traction test. Among all properties studied, hydrogels reinforced with activated attapulgite showed better mechanical resistance and Young module than the other samples. (author)

  19. Hydrogel Walkers with Electro-Driven Motility for Cargo Transport.

    Science.gov (United States)

    Yang, Chao; Wang, Wei; Yao, Chen; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2015-08-28

    In this study, soft hydrogel walkers with electro-driven motility for cargo transport have been developed via a facile mould-assisted strategy. The hydrogel walkers consisting of polyanionic poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylamide) exhibit an arc looper-like shape with two "legs" for walking. The hydrogel walkers can reversibly bend and stretch via repeated "on/off" electro-triggers in electrolyte solution. Based on such bending/stretching behaviors, the hydrogel walkers can move their two "legs" to achieve one-directional walking motion on a rough surface via repeated "on/off" electro-triggering cycles. Moreover, the hydrogel walkers loaded with very heavy cargo also exhibit excellent walking motion for cargo transport. Such hydrogel systems create new opportunities for developing electro-controlled soft systems with simple design/fabrication strategies in the soft robotic field for remote manipulation and transportation.

  20. Lima Bean Starch-Based Hydrogels | Oladebeye | Nigerian Journal ...

    African Journals Online (AJOL)

    Hydrogels were prepared by crosslinking native lima bean starch and polyvinyl alcohol (PVA) with glutaraldehyde (GA) at varying proportions in an acidic medium. The native starch (N-LBS) and hydrogels (L-GA (low glutaraldehyde) and H-GA (high glutaraldehyde)) were examined for their water absorption capacity (WAC) ...

  1. Hydrogels Prepared from Cross-Linked Nanofibrillated Cellulose

    Science.gov (United States)

    Sandeep S. Nair; J.Y. Zhu; Yulin Deng; Arthur J. Ragauskas

    2014-01-01

    Nanocomposite hydrogels were developed by cross-linking nanofibrillated cellulose with poly(methyl vinyl ether-co-maleic acid) and polyethylene glycol. The cross-linked hydrogels showed enhanced water absorption and gel content with the addition of nanocellulose. In addition, the thermal stability, mechanical strength, and modulus increased with an increase in the...

  2. Extraction of palm tree cellulose and its functionalization via graft copolymerization.

    Science.gov (United States)

    Al-Hoqbani, Abdulmajeed A; Abdel-Halim, E S; Al-Deyab, Salem S

    2014-09-01

    The work in this paper was planned with the aim of extracting the cellulosic component of palm tree waste and functionalizing this cellulose through graft copolymerization with acrylic acid. The cellulose extraction included hot alkali treatment with aqueous sodium hydroxide to remove the non-cellulosic binding materials. The alkali treatment was followed by an oxidative bleaching using peracid/hydrogen peroxide mixture with the aim of removing the rest of non-cellulosic materials to improve the fiber hydrophilicity and accessibility towards further grafting reaction. Optimum conditions for cellulose extraction are boiling in 5% (W/V) NaOH in a material to liquor ratio of 1:20 for 1 h then bleaching with 60 ml/l bleaching mixture at initial pH value of 6.5 for 30 min. The pH of the bleaching medium is turned to the alkaline range 11 and bleaching continues for extra 30 min. Graft copolymerization reaction was initiated by potassium bromate/thiourea dioxide redox system. Optimum conditions for grafting are 30 mmol of potassium bromate, 30 mmol of thiourea dioxide and 150 g of acrylic acid (each per 100 g of cellulose). The polymerization reaction was carried out for 120 min at 50°C using a material to liquor ratio of 1:20. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Development of Novel N-isopropylacrylamide (NIPAAm Based Hydrogels with Varying Content of Chrysin Multiacrylate

    Directory of Open Access Journals (Sweden)

    Shuo Tang

    2017-10-01

    Full Text Available A series of novel temperature responsive hydrogels were synthesized by free radical polymerization with varying content of chrysin multiacrylate (ChryMA. The goal was to study the impact of this novel polyphenolic-based multiacrylate on the properties of N-isopropylacrylamide (NIPAAm hydrogels. The temperature responsive behavior of the copolymerized gels was characterized by swelling studies, and their lower critical solution temperature (LCST was characterized through differential scanning calorimetry (DSC. It was shown that the incorporation of ChryMA decreased the swelling ratios of the hydrogels and shifted their LCSTs to a lower temperature. Gels with different ChryMA content showed different levels of response to temperature change. Higher content gels had a broader phase transition and smaller temperature response, which could be attributed to the increased hydrophobicity being introduced by the ChryMA.

  4. Metal-Free Alternating Copolymerization of CO2with Epoxides: Fulfilling “Green” Synthesis and Activity

    KAUST Repository

    Zhang, Dongyue

    2016-08-16

    Polycarbonates were successfully synthesized for the first time through the anionic copolymerization of epoxides with CO2, under metal-free conditions. Using an approach based on the activation of epoxides by Lewis acids and of CO, by appropriate cations, well-defined alternating copolymers made of CO, and propylene oxide (PO) or cyclohexene oxide (CHO) were indeed obtained. Triethyl borane was the Lewis acid chosen to activate the epoxides, and onium halides or onium alkoxides involving either ammonium, phosphonium, or phosphazenium cations were selected to initiate the copolymerization. In the case of PO, the carbonate content of the poly(propylene carbonate) formed was in the range of 92-99% and turnover numbers (TON) were close to 500; in the case of CHO perfectly alternating poly(cyclohexene carbonate) were obtained and TON values were close to 4000. The advantages of such a copolymerization system are manifold: (i) no need for multistep catalyst/ligand synthesis as in previous works; (ii) no transition metal involved in the copolymer synthesis and therefore no coloration of the samples isolated; and (iii) no necessity for postsynthesis purification.

  5. Electroactive behavior assessment of poly(acrylic acid)-graphene oxide composite hydrogel in the detection of cadmium

    NARCIS (Netherlands)

    Bejarano-Jimenez, A.; Escobar-Barrios, V.A.; Kleijn, J.M.; Oritz-Ledon, C.A.; Chazaro-Ruiz, L.F.

    2014-01-01

    Super absorbent polymers of acrylic acid-graphene oxide (PAA-GO) were synthesized with different percentage of chemical neutralization (0, 10, and 20%) of the acrylic acid monomer before its polymerization. The influence of their swelling and adsorption/desorption capacity of cadmium ions in aqueous

  6. LPV model development and control of a solution copolymerization reactor

    NARCIS (Netherlands)

    Rahme, S.; Abbas, H.M.S.; Meskin, N.; Tóth, R.; Mohammadpour, J.

    2016-01-01

    In this paper, linear parameter-varying (LPV) control is considered for a solution copolymerization reactor, which takes into account the time-varying nature of the parameters of the process. The nonlinear model of the process is first converted to an exact LPV model representation in the

  7. Radiation-chemical copolymerization of oligoalkylene- maleinants of alicyclic structure

    International Nuclear Information System (INIS)

    Bondarenko, P.A.; Videnina, N.G.; Omel'chenko, S.I.

    1982-01-01

    Effect of glycol used in synthesis on the properties of oligoalkylenemaleinates and their copolymers is considered. It is shown that oligoesters during copolymerization with sterol have enough high sensitivity to the effect of gamma radiation and electrons of high energy. The copolymers have a good mechanical-and-physical properties at low absorbed doses

  8. Radiation-induced copolymerization of hexafluoroacetone with α-olefins

    International Nuclear Information System (INIS)

    Matsuda, O.; Watanabe, S.; Okamoto, J.; Machi, S.; Tabata, Y.

    1977-01-01

    The copolymerization of hexafluoroacetone with higher α-olefins above butene, such as 1-pentene (I), 1-hexene (II), 1-octene (III), 2-methyl-1-butene (IV), 2-methyl-1-pentene (V), 3-methyl-1-butene (VI), and 4-methyl-1-pentene (VII) was studied at relatively low temperatures by γ-ray irradiation. Copolymerization of II, IV, V, and VII with hexafluoroacetone was found to scarcely take place at -78 0 C in bulk, but the addition of trichlorotrifluoroethane in amounts to yield equimolar mixtures resulted in conversion of 15.7 percent for IV and of 2.1 to 4.0 percent for the other α-olefins. Higher conversion of V at -78 0 C than at 0 0 C suggest that copolymerization may take place via an ionic mechanism. The effects of various additives on the copolymerization are reported. Infrared spectral studies indicated that the double bond of the α-olefins is opened to form a polymer. The C--O double bond of the hexafluoroacetone and the α-olefin double bond are opened to form the copolymer

  9. Design of protein-responsive micro-sized hydrogels for self-regulating microfluidic systems

    Science.gov (United States)

    Hirayama, Mayu; Tsuruta, Kazuhiro; Kawamura, Akifumi; Ohara, Masayuki; Shoji, Kan; Kawano, Ryuji; Miyata, Takashi

    2018-03-01

    Diagnosis sensors using micro-total analysis systems (µ-TAS) have been developed for detecting target biomolecules such as proteins and saccharides because they are signal biomolecules for monitoring body conditions and diseases. In this study, biomolecularly stimuli-responsive micro-sized hydrogels that exhibited quick shrinkage in response to lectin concanavalinA (ConA) were prepared in a microchannel by photopolymerization using a fluorescence microscope. In preparing the micro-size hydrogels, glycosyloxyethyl methacrylate (GEMA) as a ligand monomer was copolymerized with a crosslinker in the presence of template ConA in molecular imprinting. The ConA-imprinted micro-hydrogel showed greater shrinkage in response to target ConA than nonimprinted micro-hydrogel. When a buffer solution was switched to an aqueous ConA solution in the Y-shaped microchannel, the flow rates changed quickly because of the responsive shrinkage of the micro-hydrogel prepared in the microchannel. These results suggest that the ConA-imprinted micro-hydrogel acted as a self-regulated microvalve in microfluidic systems.

  10. Synthesis and characterization of arginine-NIPAAm hybrid hydrogel as wound dressing: In vitro and in vivo study.

    Science.gov (United States)

    Wu, De-Qun; Zhu, Jie; Han, Hua; Zhang, Jun-Zhi; Wu, Fei-Fei; Qin, Xiao-Hong; Yu, Jian-Yong

    2018-01-01

    A multi-functional hybrid hydrogel P(M-Arg/NIPAAm) with temperature response, anti-protein adsorption and antibacterial properties was prepared and applied as wound dressing. The hydrogel was carried out by free radical copolymerization of methacrylate arginine (M-Arg) and N-isopropyl acrylamide (NIPAAm) monomers using N,N'-methylene bisacrylamide as a crosslinker, and ammonium persulfate/N,N,N', N'-tetramethylethylenediamine as the redox initiator. To endow the antimicrobial property, chlorhexidine diacetate (CHX) was preloaded into the hydrogel and polyhexamethylene guanidine phosphate (PHMG) was grafted on the hydrogel surface, respectively. The antimicrobial property of two series of hydrogels was evaluated and compared. The successful synthesis of M-Arg, PHMG and hydrogels was proved by 13 C NMR, 1 H NMR and FTIR spectroscopy. The hydrogel morphology characterized by scanning electron microscopy confirmed that the homogeneous porous and interconnected structures of the hydrogels. The swelling, protein adsorption property, in vitro release of CHX, antimicrobial assessment, cell viability as well as in vivo wound healing in a mouse model were studied. The results showed the nontoxicity and antimicrobial P(M-Arg/NIPAAm) hydrogel accelerated the full-thickness wound healing process and had the potential application in wound dressing. Despite the zwitterionic characteristic and biocompatible property of arginine based hydrogels, the brittle behavior and non-transparency still remain as a significant problem for wound dressing. Furthermore promoting the antibacterial property of the zwitterionic hydrogel is also necessary to prevent the bacterial colonization and subsequent wound infection. Therefore, we created a hybrid hydrogel combined methacrylate arginine (M-Arg) and N-isopropyl acrylamide (NIPAAm). NIPAAm improves transparency and mechanical property as well as acts as a temperature-response drug release system. Additionally, chlorhexidine (CHX) was preloaded

  11. Concomitant monitoring of implant formation and drug release of in situ forming poly (lactide-co-glycolide acid) implants in a hydrogel matrix mimicking the subcutis using UV-vis imaging.

    Science.gov (United States)

    Sun, Yu; Jensen, Henrik; Petersen, Nickolaj J; Larsen, Susan W; Østergaard, Jesper

    2018-02-20

    For poly (lactide-co-glycolide acid) (PLGA)-based in situ forming implants, the rate of implant formation plays an important role in determining the overall drug release kinetics. Currently, in vitro techniques capable of characterizing the processes of drug release and implant formation at the same time are not available. A hydrogel-based in vitro experimental setup was recently developed requiring only microliter of formulation and forming a closed system potentially suitable for interfacing with various spectroscopic techniques. The aim of the present proof-of-concept study was to investigate the feasibility of concomitant UV imaging, Vis imaging and light microscopy for detailed characterization of the behavior of in situ forming PLGA implants in the hydrogel matrix mimicking the subcutis. The model compounds, piroxicam and α-lactalbumin were added to PLGA-1-methyl-2-pyrrolidinone and PLGA-triacetin solutions. Upon bringing the PLGA-solvent-compound pre-formulation in contact with the hydrogel, Vis imaging and light microscopy were applied to visualize the depot formation and UV imaging was used to quantify drug transport in the hydrogel. As compared to piroxicam, the α-lactalbumin invoked an acceleration of phase separation and an increase of implant size. α-Lactalbumin was released faster from the PLGA-1-methyl-2-pyrrolidinone system than the PLGA-triacetin system opposite to the piroxicam release pattern. A linear relationship between the rate of implant formation and initial compound release within the first 4h was established for the PLGA-NMP systems. This implies that phase separation may be one of the controlling factors in drug release. The rate of implant formation may be an important parameter for predicting and tailoring drug release. The approach combining UV imaging, Vis imaging and light microscopy may facilitate understanding of release processes and holds potential for becoming a useful tool in formulation development of in situ forming

  12. Supramolecular polyaniline hydrogel as a support for urease

    International Nuclear Information System (INIS)

    Słoniewska, Anna; Pałys, Barbara

    2014-01-01

    Supramolecular hydrogels of conducting polymers are successfully used in bioelectrochemistry because of their mechanical and swelling properties of gels added to the specific electron transport properties of conducting polymers. We have studied polyaniline-poly(styrene sulfonate) (PANI–PSS) hydrogel as a substrate for the urease. The hydrogels were synthesized at pH = 0 and pH = 5. PANI–PSS hydrogel is a supramolecular self-assembly material consisting of positively-charged PANI chains and negatively-charged PSS chains. The hydrogel was studied by cyclic voltammetry, infrared and Raman spectroscopy and Scanning Electron Microscopy (SEM). Raman spectra revealed presence of phenazine rings in the hydrogel structure. Phenazine rings form covalent cross-linkers contributing to the hydrogel mechanical stability. The covalent cross-linkers influence the cyclic voltammetry responses of the hydrogel in acidic media. We tested the activity of urease immobilized in the PANI–PSS hydrogel by the physical adsorption or by the covalent bonding with the carbodiimide reaction. The enzyme immobilized in hydrogels prepared at higher pH value reveals significantly higher sensitivity. The method of the enzyme immobilization has smaller impact on the sensitivity. All hydrogel sensors reveal largely higher sensitivity to urea comparing to urease immobilized in the typical electrochemically deposited PANI films. The sensitivity of urease covalently bond to the hydrogel obtained at pH = 5 was as high as 1693 μA/(mol dm 3 ). The sensor response was linear in the urea concentration range from 10 −4 to 7 × 10 −2 mol/dm 3

  13. Copolymerization parameters of N-Methacryloyloxy tetrabromophthalimide with different vinyl monomers

    International Nuclear Information System (INIS)

    Mahmoud, A.A.

    2005-01-01

    N-Methacryloyloxytetrabromophthalimide (NMTP) was synthesized by the reaction of N-hydroxytetrabromophthalimide with either methacryloyl chloride or methacrylic acid in the presence of triethylamine or N, Ndicyclohexylcarbodiimide respectively. Binary copolymerization reactions of the prepared monomer with ethyl acrylate (EA), n-butyl methacrylate (n.BMA), tertiary butylacrylate (t.BA) and vinyl acetate (VA) were performed in methylene chloride at 65 degree C using 1 mol % azobisisobutylronitrile (AIBN) as initiator. The structure of the prepared monomer was investigated by IR and 1H NMR spectroscopy. The copolymer compositions were determined from bromine analysis. Copolymerization parameters for each system were calculated by the Fineman-Ross and Kelen-Tudos methods. The monomer reactivity ratios for the systems NMTP-EA, NMTP-n.BMA, NMTP-t.BA and NMTP-VA were found to be r1 0.180, r2 = 0.893, r1 = 0.025, r2 = 0.680, r1 0.014, r2 0.956 and r1 1.002, r2 1.004 respectively

  14. Síntese e caracterização de hidrogéis compósitos a partir de copolímeros acrilamida-acrilato e caulim: efeito da constituição de diferentes caulins do nordeste brasileiro Synthesis and characterization of poly (acrylamide-co-acrylate and kaolin hydrogel composites: effect of the constitution of different kaolins from northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Carlos W. de Q. Brito

    2013-01-01

    Full Text Available Superabsorbent hydrogels based on poly (acrylamide-co-acrylate and different kaolins, were prepared by free-radical aqueous copolymerization. FTIR and WAXS techniques were employed for characterization of a series of hydrogels, obtained by varying the percentage of clay, crosslinking and constitution of kaolin. The water absorbency at equilibrium (Weq decreased with increasing clay content and the amount of crosslinking agent. Superabsorbent hydrogel (Weq > 1084 g H2O/g gel was obtained as 10 wt% of white kaolin and 0.05 mol% of crosslinking agent were used. The hydrogel proved sensitive to pH variation and the presence of salts.

  15. Co-delivery of a laminin-111 supplemented hyaluronic acid based hydrogel with minced muscle graft in the treatment of volumetric muscle loss injury.

    Directory of Open Access Journals (Sweden)

    Stephen M Goldman

    Full Text Available Minced muscle autografting mediates de novo myofiber regeneration and promotes partial recovery of neuromuscular strength after volumetric muscle loss injury (VML. A major limitation of this approach is the availability of sufficient donor tissue for the treatment of relatively large VMLs without inducing donor site morbidity. This study evaluated a laminin-111 supplemented hyaluronic acid based hydrogel (HA+LMN as a putative myoconductive scaffolding to be co-delivered with minced muscle grafts. In a rat tibialis anterior muscle VML model, delivery of a reduced dose of minced muscle graft (50% of VML defect within HA+LMN resulted in a 42% improvement of peak tetanic torque production over unrepaired VML affected limbs. However, the improvement in strength was not improved compared to a 50% minced graft-only control group. Moreover, histological analysis revealed that the improvement in in vivo functional capacity mediated by minced grafts in HA+LMN was not accompanied by a particularly robust graft mediated regenerative response as determined through donor cell tracking of the GFP+ grafting material. Characterization of the spatial distribution and density of macrophage and satellite cell populations indicated that the combination therapy damps the heightened macrophage response while re-establishing satellite content 14 days after VML to a level consistent with an endogenously healing ischemia-reperfusion induced muscle injury. Moreover, regional analysis revealed that the combination therapy increased satellite cell density mostly in the remaining musculature, as opposed to the defect area. Based on the results, the following salient conclusions were drawn: 1 functional recovery mediated by the combination therapy is likely due to a superposition of de novo muscle fiber regeneration and augmented repair of muscle fibers within the remaining musculature, and 2 The capacity for VML therapies to augment regeneration and repair within the

  16. Antifouling properties of hydrogels

    International Nuclear Information System (INIS)

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

    2011-01-01

    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. (topical review)

  17. Antifouling properties of hydrogels

    Directory of Open Access Journals (Sweden)

    Takayuki Murosaki, Nafees Ahmed and Jian Ping Gong

    2011-01-01

    Full Text Available 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.

  18. Evaluation of Hydrogels Based on Poloxamer 407 and Polyacrylic ...

    African Journals Online (AJOL)

    HP

    Keywords: Hydrogels, Gentamicin, Polyacrylic acid, Viscosity, Bioactivity, Poloxamer 407. Tropical Journal of Pharmaceutical Research is indexed by Science Citation Index (SciSearch), ... among others, have been made to determine its.

  19. Preparation and in vitro evaluation of carboxymethylated κ-carrageenan aluminum hydrogel microbeads for prolonged release of mefenamic acid

    International Nuclear Information System (INIS)

    Beron, Pia Maria G.; Cruzado, Shervin T.; Dela Cruz, Sharmaine F.; Estanislao, Fides Mae L.; Evangelista, Charina Joy; Mandocdoc, Larra Minnellie W.; Salas, Sharlaine B.; Tiu, Mark Brian C.; Carigma, Andrea Q.; Bayquen, Aristea V.

    2012-01-01

    Polymers that swell in an aqueous medium have been widely used to formulate controlled-release dosage forms. This study aims to prepare carboxymethyl κ-carrageenan (CMKC) microbeads and evaluate its potential for controlled release of mefenamic acid in comparison to the positive control, carboxymethylcellulose (CMC) microbeads. The powdered κ-carrageenan was carboxymethylated and Fourier-Transform Infrared Spectroscopy confirmed the carboxy methylation. Aqueous solutions of CMC (3% w/v) and CMKC (3%, 4%, 5% w/v) were prepared as microbeads using ionotropic gelation technique. Microbeads were loaded with mefenamic acid by suspending it in the aqueous solution (0.5% w/v) of the drug for 72 hours. Particle size and surface morphology were characterized using scanning electron microscopy. One-way ANOVA was used to determine a significant difference between the release activity of the drug-loaded CMKC and CMC microbeads. Differential Scanning Calorimetry was performed on the drug, drug- free, and drug-loaded microbeads of CMC and CMKC. Two-way ANOVARM showed significant interaction in % drug release of the three groups being analyzed in respect to time effect (p≤0.001) and group effect (p≤0.001). Post Hoc Duncan Multiple Range Test showed that 3% CMC and 4% CMKC has equal average % drug release values and is significantly higher compared to the commercial mefenamic acid. Also, one way ANOVA showed that 3% CMC was able to release the drug with no significant difference in time (p = 0.159), while 4% CMKC (p < 0.001) and the commercial mefenamic acid (p≤0.001) were able to release the drug with significant difference in time (author)

  20. Radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate)

    International Nuclear Information System (INIS)

    Gonzalez Torres, Maykel; Rapado Paneque, Manuel; Paredes Zaldivar, Mayte; Altanes Valentin, Sonia; Barrera Gonzalez, Gisela

    2008-01-01

    The graft copolymer poly (3-hydroxybutyrate)-g- polyacrylamide [P (HB-g-AAm)] was synthesized by radiation induced graft copolymerization of acrylamide onto poly (3-hydroxybutyrate). The study was conducted by the simultaneous irradiation method. The structure of [P (HB-g-AAm)] was identified by Fourier Transform Infrared (FTIR) spectroscopy. Thermal behavior of the graft copolymer was also studied by Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). From the results it was found that FTIR studies showed new signals (stretching -N-H) as strong evidence of grafting. The grafting degree was found to be 10 % and the thermodynamic parameter obtained from the DSC thermogram of plain PHB and the graft copolymer varied showing decrease in the material crystallinity and increase in the glass transition temperature. These results demonstrate that the radiation induced graft copolymerization reaction of acrylamide onto PHB was successively achieved. (Author)

  1. Catalytic Copolymerization of Ethene and Carbon Monoxide on Nickel Complexes.

    Science.gov (United States)

    Domhöver, Bernd; Kläui, Wolfgang; Kremer-Aach, Andreas; Bell, Ralf; Mootz, Dietrich

    1998-11-16

    Can palladium be replaced by nickel? For the industrial copolymerization of carbon monoxide and ethene a palladium catalyst is used which cannot be recovered-a cheaper procedure would be desirable. The presented complex 1 is the first structurally characterized nickel compound which does not polymerize ethene but a mixture from carbon monoxide and ethene unter mild conditions to give a perfectly alternating polyketone. © 1998 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

  2. Recent advances in photoinduced donor/acceptor copolymerization

    International Nuclear Information System (INIS)

    Joensson, S.; Viswanathan, K.; Hoyle, C.E.; Clark, S.C.; Miller, C.; Morel, F.; Decker, C.

    1999-01-01

    Photoinitiated free radical polymerization of donor (D)/acceptor (A) type monomers has gained considerable interest due to the possibility to efficiently photopolymerize non-acrylate based systems. Furthermore, this photoinduced alternating copolymerization can be accomplished without the presence of a conventional free radical generating photoinitiator. In the past, we have shown that the structural influences in the direct photolysis of N-Alkyl and N-Arylmaleimides as well as their corresponding ground state charge transfer complexes (CTC) with suitable donors have carefully been investigated. For certain combinations of A and D type monomers, a direct photolysis of the ground state complex or the excitation of the acceptor, followed by the formation of an exciplex, has been shown to initiate the copolymerization. Herein, we show that the main route of initiation is based on inter or intra molecular H-abstraction from an excited state maleimide, whereby no exciplex formation takes place. H-abstraction will predominantly take place in systems where easily abstractable hydrogens are present. Our laser flash photolysis investigation, ESR (A. Hiroshi, I. Takasi, T. Nosi, Macromol. Chem. 190 (1989) 2821) and phosphorescence emissions (K.S. Chen, T. Foster, J.K.S. Wan, J. Phys. Chem. 84 (1980) 2473; C.J. Seliskar, S.P. McGlynn, J. Chem. Phys. 55 (1971) 4337) studies show that triplet excited states of N-alkyl substituted maleimides (RMI), which are well known strong precursors for direct H-abstractions from aliphatic ethers and secondary alcohols, are formed upon excitation. Rates of copolymerization and degrees of conversion for copolymerization of maleimide/vinyl ether pairs in air and nitrogen have been measured as a function of hydrogen abstractability of the excited triplet state MI as well as the influence of concentration and hydrogen donating effect of the hydrogen donor

  3. An Injectable Composite Gelatin Hydrogel with pH Response Properties

    Directory of Open Access Journals (Sweden)

    Baoguo Chen

    2017-01-01

    Full Text Available On account of minimally invasive procedure and of filling irregular defects of tissues, injectable hydrogels are increasingly attractive in biomedical fields. However, traditional hydrogel formed by simple physical interaction or in situ crosslinking had inevitably some drawbacks such as low mechanical strength and lack of multifunctional properties. Though many investigations had successfully modified traditional injectable hydrogel to obtain both mechanical and functional properties, an acetalated β-cyclodextrin (Ac-β-CD nanoparticle composite injectable hydrogel designed in the research was another effective and efficient choice to solve the drawbacks. First of all, gelatin derivative (G-AA and Ac-β-CD were synthesized to prepare hydrogel and nanoparticle, respectively. In order to ensure good compatibility between nanoparticle and macromonomer and provide crosslink points between nanoparticle and macromonomer, G-AA was simultaneously functionalized onto the surface of Ac-β-CD nanoparticle during the fabrication of Ac-β-CD nanoparticle using one-step method. Finally, injectable composite hydrogel was obtained by photoinitiated polymerization in situ. Hydrogel properties like gelation time and swelling ratio were investigated. The viscoelastic behavior of hydrogels confirmed that typical characteristics of crosslinked elastomer for all hydrogel and nanoparticle in hydrogel could improve the mechanical property of hydrogel. Moreover, the transparency with time had verified obvious acid-response properties of hydrogels.

  4. Electrochemical copolymerization of thiophene derivatives; a precursor to photovoltaic devices

    International Nuclear Information System (INIS)

    Kumar, Prajwal; Ranjith, K.; Gupta, Satyajit; Ramamurthy, Praveen C.

    2011-01-01

    Highlights: → This work presents an electrochemical technique for the polymerization and copolymerization of thiophene derivatives. → Copolymerization of thiophene based monomers like 7,9-dithiophene-2yl-8H-cyclopenta[a]acenaphthalene-8-one and 3-hexylthiophene are synthesized. → Study of the structural, optical, thermal, conductivity, morphological, band gap and impedance measurements of the copolymer indicates a suitable material for photovoltaic applications. - Abstract: This work presents an electrochemical technique for the polymerization and copolymerization of thiophene derivatives like 7,9-dithiophene-2yl-8H-cyclopenta[a]acenaphthalene-8-one and 3-hexylthiophene. The structural characterization of chemically synthesized monomers and electrochemically synthesized polymers was carried out by nuclear magnetic resonance and Fourier transform infrared spectroscopy. Thermal characterizations indicate that copolymer has increased thermal stability than that of homopolymer. Morphological studies of the polymerized films carried out by scanning electron microscopy shows network structure of copolymer. Optical properties of the homopolymers and copolymer were studied by UV-visible spectrometer and it was observed that band gap of copolymer is less than the homopolymers. HOMO and LUMO levels, band gap values of the respective polymers were also calculated from the cyclic voltammetry technique with various scan rates. By the peak current obtained from various scan rates shows that all polymerization reactions are diffusion controlled process. Charge transfer resistances of polymers were determined using Nyquist plots. Conductivity of synthesized polymers shows higher conductivity for copolymer than homopolymers.

  5. Carboxymethylcellulose hydrogel crosslinked with citric acid for biomedical application; Reticulacao de hidrogeis de carboximetilcelulose com acido citrico para aplicacoes biomedicas

    Energy Technology Data Exchange (ETDEWEB)

    Capanema, Nadia S.V.; Mansur, Alexandra A.P.; Mansur, Herman S., E-mail: nsvnadia@gmail.com [Centro de Nanociencias, Nanotecnologia e Inovacao (CeNano), MG (Brazil); Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Metalurgica e Materiais

    2016-07-01

    The carboxymethylcellulose (CMCel) has been extensively used in order application as flexible polymer membrane. Biopolymers crosslinked have been studied to optimize their performance in biomedical applications. In this work, CMCel films with a degree of substitution (DS = 0.77) were prepared by evaporation of solvent and crosslinked with different concentrations of citric acid (CA). The synthesized CMCel was characterized by Infrared Spectroscopy by Fourier Transform X-ray spectroscopy (FTIR), and morphology assessed by scanning electron microscopy (SEM). Morphological analysis performed using the SEM indicated the crosslinked CMCel and not crosslinked with a very smooth and uniform appearance. The FTIR results indicated the modification of existing bands and appearance of a new band 1715 cm{sup -1} suggesting that there has been change in the structure of the crosslinked CMCel. (author)

  6. Development of a radiochromic ferric oligomer hydrogel

    International Nuclear Information System (INIS)

    Jordan, Kevin; Sekimoto, Masaya

    2010-01-01

    Ferrous gelatin hydrogels were prepared by using sulphuric acid concentrations lower than required to maintain radiation induced ferric ions fully hydrated. The ferric hydroxyl species that are produced following irradiation exhibit a radiochromic response that can be probed with blue light. The dose distribution shapes were stable in time, indicating no long term diffusion. An over response to dose gradients was observed both in one centimeter cuvette samples and litre volumes probed with optical cone beam CT. This ferrous hydrogel may represent a model system for studying iron radiochemistry in biological systems.

  7. Theoretical analysis of factors controlling the nonalternating CO/C(2)H(4) copolymerization.

    Science.gov (United States)

    Haras, Alicja; Michalak, Artur; Rieger, Bernhard; Ziegler, Tom

    2005-06-22

    A [P-O]Pd catalyst based on o-alkoxy derivatives of diphenylphosphinobenzene sulfonic acid (I) has recently been shown by Drent et al. to perform nonalternating CO/C(2)H(4) copolymerization with subsequent incorporation of ethylene units into the polyketone chain. The origin of the nonalternation is investigated in a theoretical study of I, where calculated activation barriers and reaction heats of all involved elementary steps are used to generate a complete kinetic model. The kinetic model is able to account for the observed productivity and degree of nonalternation as a function of temperature. Consistent with the energy changes obtained for the real catalyst model, the selectivity toward a nonalternating distribution of both comonomers appears to be mainly a result of a strong destabilization of the Pd-acyl complex.

  8. Synthesis of Acylated Xylan-Based Magnetic Fe3O4 Hydrogels and Their Application for H2O2 Detection

    Directory of Open Access Journals (Sweden)

    Qing-Qing Dai

    2016-08-01

    Full Text Available Acylated xylan-based magnetic Fe3O4 nanocomposite hydrogels (ACX-MNP-gels were prepared by fabricating Fe3O4 nanoctahedra in situ within a hydrogel matrix which was synthesized by the copolymerization of acylated xylan (ACX with acrylamide and N-isopropylacrylamide under ultraviolet irradiation. The size of the Fe3O4 fabricated within the hydrogel matrix could be adjusted through controlling the crosslinking concentrations (C. The magnetic hydrogels showed desirable magnetic and mechanical properties, which were confirmed by XRD, Raman spectroscopy, physical property measurement system, SEM, TGA, and compression test. Moreover, the catalytic performance of the magnetic hydrogels was explored. The magnetic hydrogels (C = 7.5 wt % presented excellent catalytic activity and provided a sensitive response to H2O2 detection even at a concentration level of 5 × 10−6 mol·L−1. This approach to preparing magnetic hydrogels loaded with Fe3O4 nanoparticles endows xylan-based hydrogels with new promising applications in biotechnology and environmental chemistry.

  9. A Triblock Copolymer Design Leads to Robust Hybrid Hydrogels for High-Performance Flexible Supercapacitors.

    Science.gov (United States)

    Zhang, Guangzhao; Chen, Yunhua; Deng, Yonghong; Wang, Chaoyang

    2017-10-18

    We report here an intriguing hybrid conductive hydrogel as electrode for high-performance flexible supercapacitor. The key is using a rationally designed water-soluble ABA triblock copolymer (termed as IAOAI) containing a central poly(ethylene oxide) block (A) and terminal poly(acrylamide) (PAAm) block with aniline moieties randomly incorporated (B), which was synthesized by reversible additional fragment transfer polymerization. The subsequent copolymerization of aniline monomers with the terminated aniline moieties on the IAOAI polymer generates a three-dimensional cross-linking hybrid network. The hybrid hydrogel electrode demonstrates robust mechanical flexibility, remarkable electrochemical capacitance (919 F/g), and cyclic stability (90% capacitance retention after 1000 cycles). Moreover, the flexible supercapacitor based on this hybrid hydrogel electrode presents a large specific capacitance (187 F/g), superior to most reported conductive hydrogel-based supercapacitors. With the demonstrated additional favorable cyclic stability and excellent capacitive and rate performance, this hybrid hydrogel-based supercapacitor holds great promise for flexible energy-storage device.

  10. Injectable, Biomolecule-Responsive Polypeptide Hydrogels for Cell Encapsulation and Facile Cell Recovery through Triggered Degradation.

    Science.gov (United States)

    Xu, Qinghua; He, Chaoliang; Zhang, Zhen; Ren, Kaixuan; Chen, Xuesi

    2016-11-16

    Injectable hydrogels have been widely investigated in biomedical applications, and increasing demand has been proposed to achieve dynamic regulation of physiological properties of hydrogels. Herein, a new type of injectable and biomolecule-responsive hydrogel based on poly(l-glutamic acid) (PLG) grafted with disulfide bond-modified phloretic acid (denoted as PLG-g-CPA) was developed. The hydrogels formed in situ via enzymatic cross-linking under physiological conditions in the presence of horseradish peroxidase and hydrogen peroxide. The physiochemical properties of the hydrogels, including gelation time and the rheological property, were measured. Particularly, the triggered degradation of the hydrogel in response to a reductive biomolecule, glutathione (GSH), was investigated in detail. The mechanical strength and inner porous structure of the hydrogel were influenced by the addition of GSH. The polypeptide hydrogel was used as a three-dimensional (3D) platform for cell encapsulation, which could release the cells through triggered disruption of the hydrogel in response to the addition of GSH. The cells released from the hydrogel were found to maintain high viability. Moreover, after subcutaneous injection into rats, the PLG-g-CPA hydrogels with disulfide-containing cross-links exhibited a markedly faster degradation behavior in vivo compared to that of the PLG hydrogels without disulfide cross-links, implying an interesting accelerated degradation process of the disulfide-containing polypeptide hydrogels in the physiological environment in vivo. Overall, the injectable and biomolecule-responsive polypeptide hydrogels may serve as a potential platform for 3D cell culture and easy cell collection.

  11. Synthesis of poly (acrylamide-co-metacrylic acid) hydrogels By means of gamma irradiation techniques: influence of Absorbed dose on the swelling process

    International Nuclear Information System (INIS)

    Rapado, Manuel; Altanes, Sonia; Sainz, Dianelys; Prado, Stalina

    1999-01-01

    In this report gamma radiation techniques were performed a double function of proceeding the processes of polymerization and crosslinking with the advantage of avoid the uses of chemicals crosslinks. The influence of absorbed dose on the swelling ratio as a function of pH have been presented. For these hydrogels, swelling studies indicated that swelling decrease with the increase of the absorbed dose from 10 to 50 kGy. It was confirmed that at the firsts stages (100-150 min) the diffusion studies were in accordance with Fickian behavior and the diffusion coefficients were obtained, whereas the latest stages were in good agreement with second-order diffusion kinetics proposed by Schott 1 .These news hydrogels exhibit a higher degree of swelling, a factor that, a priori, assures high biocompatibility because it increases the similarity with living tissues

  12. Photoreversible Covalent Hydrogels for Soft-Matter Additive Manufacturing.

    Science.gov (United States)

    Kabb, Christopher P; O'Bryan, Christopher S; Deng, Christopher C; Angelini, Thomas E; Sumerlin, Brent S

    2018-05-16

    Reversible covalent chemistry provides access to robust materials with the ability to be degraded and reformed upon exposure to an appropriate stimulus. Photoresponsive units are attractive for this purpose, as the spatial and temporal application of light is easily controlled. Coumarin derivatives undergo a [2 + 2] cycloaddition upon exposure to long-wave UV irradiation (365 nm), and this process can be reversed using short-wave UV light (254 nm). Therefore, polymers cross-linked by coumarin groups are excellent candidates as reversible covalent gels. In this work, copolymerization of coumarin-containing monomers with the hydrophilic comonomer N, N-dimethylacrylamide yielded water-soluble, linear polymers that could be cured with long-wave UV light into free-standing hydrogels, even in the absence of a photoinitiator. Importantly, the gels were reverted back to soluble copolymers upon short-wave UV irradiation. This process could be cycled, allowing for recycling and remolding of the hydrogel into additional shapes. Further, this hydrogel can be imprinted with patterns through a mask-based, post-gelation photoetching method. Traditional limitations of this technique, such as the requirement for uniform etching in one direction, have been overcome by combining these materials with a soft-matter additive manufacturing methodology. In a representative application of this approach, we printed solid structures in which the interior coumarin-cross-linked gel is surrounded by a nondegradable gel. Upon exposure to short-wave UV irradiation, the coumarin-cross-linked gel was reverted to soluble prepolymers that were washed away to yield hollow hydrogel objects.

  13. Modification of natural leather by grafting emulsion copolymerization technique

    International Nuclear Information System (INIS)

    Badran, A.S.; Nasr, H.E.; El-Halawany, N.R.; Mohamed, W.S.

    2005-01-01

    Grafting emulsion copolymerization of methyl methacrylate (MMA) with butyl acrylate of different molar ratios onto natural leather with different molar ratios was carried out using developed redox initiation system of potassium persulphate (PPS) as an oxidizing agent and some sodium bisulphite adducts as reducing agent, as well as sodium dodecyl sulphate (SDS) was used as an anionic emulsifier. The grafted leather was characterized via FTIR, SEM and thermal gravimetric analysis. Moreover, the grafted leather was evaluated through water absorption, tensile strength, dyeing performance and hardness measurements. The obtained results revealed that the physical and mechanical properties of the modified leather were enhanced

  14. Study On The Application Of Hydrogel Prepared By Radiation Technique For Fermentation Of Sawdust

    International Nuclear Information System (INIS)

    Le Thuy Trang; Nguyen Huynh Phuong Uyen; Vo Thu Ha; Le Quang Luan

    2011-01-01

    The super water-adsorption hydrogels was successfully preparation by radiation crosslinking CMC in paste condition and radiation grafting acrylic acid into starch. The hydrogel with 76.36% gel fraction and 91.13% swelling degree were obtained by irradiation of CMC 20% at 20 kGy, while the hydrogel with 65.3% gel fraction and 234 swelling degree was acrylic acid and starch at 4 kGy. The supplementation of hydrogels prepared by radiation technique showed a higher cellulose degradation effect of waste of cattle after fermenting 30 and 45 days. The optimum condition was determined by mixing 1% (w/w) dried hydrogel in 99% (w/w) waste of cattle. The fermented sawdust using hydrogel prepared by radiation technique showed a better effect on the growth of F1 Chinese cabbage (Brassica Pe-tsai Bailey L.). (author)

  15. Improvement in the water retention characteristics of sandy loam soil using a newly synthesized poly(acrylamide-co-acrylic acid)/AlZnFe2O4 superabsorbent hydrogel nanocomposite material.

    Science.gov (United States)

    Shahid, Shaukat Ali; Qidwai, Ansar Ahmad; Anwar, Farooq; Ullah, Inam; Rashid, Umer

    2012-08-03

    The use of some novel and efficient crop nutrient-based superabsorbent hydrogel nanocomposites (SHNCs), is currently becoming increasingly important to improve the crop yield and productivity, due to their water retention properties. In the present study a poly(Acrylamide-co-acrylic acid)/AlZnFe2O4 superabsorbent hydrogel nanocomposite was synthesized and its physical properties characterized using Energy Dispersive X-ray (EDX), FE-SEM and FTIR spectroscopic techniques. The effects of different levels of SHNC were studied to evaluate the moisture retention properties of sandy loam soil (sand 59%, silt 21%, clay 19%, pH 7.4, EC 1.92 dS/m). The soil amendment with 0.1, 0.2, 0.3 and 0.4 w/w% of SHNC enhanced the moisture retention significantly at field capacity compared to the untreated soil. Besides, in a separate experiment, seed germination and seedling growth of wheat was found to be notably improved with the application of SHNC. A delay in wilting of seedlings by 5-8 days was observed for SHNC-amended soil, thereby improving wheat plant growth and establishment.

  16. GRAFT COPOLYMERIZATION OF OLYGOESTERACRYLATES WITH LIQUID RUBBER AND COPOLYMER’S CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Y. A. Anisimov

    2015-02-01

    Full Text Available The kinetic of graft copolymerization of threeethyleneglicoldimethacrylate and di threeethyleneglicolftalatedimethacrylate with liquid buthadiene rubber have been studied as a function of the olygomers composition. The experimental constants of copolymerization rate and efficiency olygoesteracrylates graft to liquid rubber were determined. The ihfluence of olygoesteracrylates’ nature on the grafting efficiency to olygomer rubber is determined and the strength characteristics are found.

  17. One-Pot Automated Synthesis of Quasi Triblock Copolymers for Self-Healing Physically Crosslinked Hydrogels.

    Science.gov (United States)

    Voorhaar, Lenny; De Meyer, Bernhard; Du Prez, Filip; Hoogenboom, Richard

    2016-10-01

    The preparation of physically crosslinked hydrogels from quasi ABA-triblock copolymers with a water-soluble middle block and hydrophobic end groups is reported. The hydrophilic monomer N-acryloylmorpholine is copolymerized with hydrophobic isobornyl acrylate via a one-pot sequential monomer addition through reversible addition fragmentation chain-transfer (RAFT) polymerization in an automated parallel synthesizer, allowing systematic variation of polymer chain length and hydrophobic-hydrophilic ratio. Hydrophobic interactions between the outer blocks cause them to phase-separate into larger hydrophobic domains in water, forming physical crosslinks between the polymers. The resulting hydrogels are studied using rheology and their self-healing ability after large strain damage is shown. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Polypeptide based hydrogels

    OpenAIRE

    Hanay, Saltuk

    2018-01-01

    There is a need for biocompatible, biodegradable, 3-D printable and stable hydrogels especially in the areas of tissue engineering, drug delivery, bio-sensing technologies and antimicrobial coatings. The main aim of this Ph.D. work was to fabricate polypeptide based hydrogel which may find a potential application in those fields. Focusing on tyrosine or tryptophan-containing copolypeptides prepared by NCarboxyanhydride (NCA) polymerizations, three different crosslinking strategies have been t...

  19. Gold recovery onto poly(acrylamide-allylthiourea) hydrogels synthesized by treating with gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kilic, A. Guelden [Hacettepe University, Department of Chemistry, 06532 Ankara (Turkey); Malci, Savas [Hacettepe University, Department of Chemistry, 06532 Ankara (Turkey); Celikbicak, Oemuer [Hacettepe University, Department of Chemistry, 06532 Ankara (Turkey); Sahiner, Nurettin [Hacettepe University, Department of Chemistry, 06532 Ankara (Turkey); Salih, Bekir [Hacettepe University, Department of Chemistry, 06532 Ankara (Turkey)]. E-mail: bekir@hacettepe.edu.tr

    2005-08-15

    Poly(acrylamide-1-allyl-2-thiourea) hydrogels, Poly(AAm-ATU), were synthesized by gamma irradiation using a {sup 60}Co {gamma} source at different irradiation dose rates and in a monomer mixture with different 1-allyl-2-thiourea contents. These hydrogels were used for the specific gold recovery from single and competitive media. It was observed that the gold adsorption capacity onto the hydrogels was high at low pHs and reached a maximum value at pH 0.5. It was found that the adsorption capacity of the hydrogels for gold ions in acidic media around pH 0.5 was high and about 940 mg g{sup -1} dry hydrogel. Adsorption of these hydrogels for gold ions was found to be very fast and also these hydrogels were showed extremely high selectivity to the gold ions in acidic media even when the concentrations of the other metal ions were extremely higher than that of the gold. Because of the high specificity of these hydrogels to gold ions compared with the other metal ions at low pHs, all matrix effects could be easily eliminated by adsorbing gold ions onto the hydrogels at around pH 0.5 and desorbing into 0.8 M thiourea in 3.0 M HCl. The swellability of the synthesized hydrogels varied with irradiation dose rates and increased at high irradiation dose rates. The minimum swellability of the hydrogels was found to be at least 1000% which made it attractive for gold to penetrate into the hydrogels and react with all the functional groups in the interior surface of the hydrogels.

  20. Radiation Synthesis of Stimuli-Responsive Hydrogels for Biological Applications

    International Nuclear Information System (INIS)

    Eid, M.; Hegazy, S.A.

    2009-01-01

    Poly(acrylamide/maleic acid/gelatin) P(AAm/MA/G) hydrogel networks were synthesized by 60 Co gamma irradiation at different doses. The properties of the hydrogels such as gelation percent, porosity, and moisture retention were investigated. The swelling ratio (S), equilibrium water content (EWC) and diffusion characteristics, including equilibrium swelling ratio (ESR), diffusion constant (n) and diffusion coefficients (D) were investigated and a non-Fickian type of diffusion characteristics was found in all the swelling media for the diffusion of water into these hydrogels. Further, the swelling pattern of P(AAm/MA/G) hydrogels was studied in different physiological bio-fluids, ph and ionic/salt solutions and showed great responsiveness due to their ionic character. The penetration velocity (v) of these biological fluids into such hydrogels was also calculated and it was found to be the maximum in urea and the minimum in synthetic urine. The higher equilibrium water content of these hydrogels, promotes them to be used as biomedical/pharmaceutical technology. The caffeine release as a drug model has been studied at ph 1 and ph 7 to resemble the ph of the stomach and the intestine, respectively. The caffeine release was controlled by the hydrogel crosslinking density that caused in increase of the irradiation dose

  1. Significance of Glucose Addition on Chitosan-Glycerophosphate Hydrogel Properties

    Directory of Open Access Journals (Sweden)

    Dian Susanthy

    2016-03-01

    Full Text Available Chitosan-glycerophosphate hydrogel can be used as dental scaffold due to its thermosensitivity, gelation performance at body temperature, suitable acidity for body condition, biocompatibility, and ability to provide good environment for cell proliferation and differentiation. Previous study showed that glucose addition to the chitosan solution before steam sterilization improved its hydrogel mechanical strength. However, the effectiveness of glucose addition was still doubted because glucose might undergo Maillard reaction in that particular condition. The aims of this study are to confirm whether the glucose addition can increase the hydrogel mechanical strength and gelation rate effectively and also to compare their performance to be dental scaffold. This research was performed through several steps, namely preparation of chitosan-glycerophosphate solution, addition of glucose, gelation time test, gel mechanical strength measurement, functional group analysis, and physical properties measurements (pH, viscosity, and pore size. The result showed that glucose addition did not improve the hydrogel mechanical strength and gelation rate, neither when it was added before nor after steam sterilization. Glucose addition before steam sterilization seemed to trigger Maillard reaction or browning effect, while glucose addition after steam sterilization increased the amount of free water molecules in the hydrogel. Chitosan and glycerophosphate interact physically, but interaction between chitosan and glucose seems to occur chemically and followed by the formation of free water molecules. Glucose addition decreases the solution viscosity and hydrogel pore size so the hydrogel performance as dental scaffold is lowered.

  2. Intra-Articular Injection of Cross-Linked Hyaluronic Acid-Dexamethasone Hydrogel Attenuates Osteoarthritis: An Experimental Study in a Rat Model of Osteoarthritis.

    Science.gov (United States)

    Zhang, Zhiwei; Wei, Xiaochun; Gao, Jizong; Zhao, Yu; Zhao, Yamin; Guo, Li; Chen, Chongwei; Duan, Zhiqing; Li, Pengcui; Wei, Lei

    2016-04-15

    Cross-linked hyaluronic acid hydrogel (cHA gel) and dexamethasone (Dex) have been used to treat knee osteoarthritis (OA) in clinical practice owing to their chondroprotective and anti-inflammatory effects, respectively. The aim of the present study was to compare the treatment effects of the cHA gel pre-mixed with/without Dex in a surgery-induced osteoarthritis model in rats. Anterior cruciate ligament transection (ACLT) surgery was performed on the right knee of rats to induce OA. Male 2-month-old Sprague-Dawley rats were randomly divided into five groups (n = 10/per group): (1) ACLT + saline; (2) ACLT + cHA gel; (3) ACLT + cHA-Dex (0.2 mg/mL) gel; (4) ACLT + cHA-Dex (0.5 mg/mL) gel; (5) Sham + saline. Intra-joint injections were performed four weeks after ACLT in the right knee. All animals were euthanized at 12 weeks post-surgery. Cartilage damage and changes in the synovial membrane were assessed by micro X-ray, Indian ink articular surface staining, Safranin-O/Fast Green staining, immunohistochemistry, hematoxylin and eosin staining of the synovial membrane, and quantitative reverse transcription-polymerase chain reaction for changes in gene expression. Micro X-ray revealed that the knee joint treated with the cHA-Dex gel was wider than those treated with cHA gel alone or saline. The cHA-Dex gel group had less Indian ink staining (indicator of cartilage fibrillation) than the cHA gel or saline injection groups. Safranin-O/Fast Green staining indicated that increased proteoglycan staining and less cartilage damage were found in the cHA-Dex gel group compared with the cHA gel or saline injection groups. Quantification of histology findings from saline, cHA gel, cHA-Dex (0.2 mg/mL) gel, cHA-Dex (0.5 mg/mL) gel, and sham groups were 5.84 ± 0.29, 4.50 ± 0.87, 3.00 ± 1.00, 2.00 ± 0.48, and 0.30 ± 0.58 (p < 0.05), respectively. A strong staining of type II collagen was found in both the cHA-Dex gel groups compared with saline group or cHA alone group. Similar

  3. Intra-Articular Injection of Cross-Linked Hyaluronic Acid-Dexamethasone Hydrogel Attenuates Osteoarthritis: An Experimental Study in a Rat Model of Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Zhiwei Zhang

    2016-04-01

    Full Text Available Cross-linked hyaluronic acid hydrogel (cHA gel and dexamethasone (Dex have been used to treat knee osteoarthritis (OA in clinical practice owing to their chondroprotective and anti-inflammatory effects, respectively. The aim of the present study was to compare the treatment effects of the cHA gel pre-mixed with/without Dex in a surgery-induced osteoarthritis model in rats. Anterior cruciate ligament transection (ACLT surgery was performed on the right knee of rats to induce OA. Male 2-month-old Sprague-Dawley rats were randomly divided into five groups (n = 10/per group: (1 ACLT + saline; (2 ACLT + cHA gel; (3 ACLT + cHA-Dex (0.2 mg/mL gel; (4 ACLT + cHA-Dex (0.5 mg/mL gel; (5 Sham + saline. Intra-joint injections were performed four weeks after ACLT in the right knee. All animals were euthanized at 12 weeks post-surgery. Cartilage damage and changes in the synovial membrane were assessed by micro X-ray, Indian ink articular surface staining, Safranin-O/Fast Green staining, immunohistochemistry, hematoxylin and eosin staining of the synovial membrane, and quantitative reverse transcription-polymerase chain reaction for changes in gene expression. Micro X-ray revealed that the knee joint treated with the cHA-Dex gel was wider than those treated with cHA gel alone or saline. The cHA-Dex gel group had less Indian ink staining (indicator of cartilage fibrillation than the cHA gel or saline injection groups. Safranin-O/Fast Green staining indicated that increased proteoglycan staining and less cartilage damage were found in the cHA-Dex gel group compared with the cHA gel or saline injection groups. Quantification of histology findings from saline, cHA gel, cHA-Dex (0.2 mg/mL gel, cHA-Dex (0.5 mg/mL gel, and sham groups were 5.84 ± 0.29, 4.50 ± 0.87, 3.00 ± 1.00, 2.00 ± 0.48, and 0.30 ± 0.58 (p < 0.05, respectively. A strong staining of type II collagen was found in both the cHA-Dex gel groups compared with saline group or cHA alone group

  4. Thermo-responsive hydrogels for intravitreal injection and biomolecule release

    Science.gov (United States)

    Drapala, Pawel

    In this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for improved treatment of Age-Related Macular Degeneration (AMD). Thermo-responsive hydrogels derived from N-isopropylacrylamide (NIPAAm) and cross-linked with poly(ethylene glycol) (PEG) poly(L-Lactic acid) (PLLA) copolymer were synthesized via free-radical polymerization. These materials were investigated for (a) phase change behavior, (b) in-vitro degradation, (c) capacity for controlled drug delivery, and (d) biocompatibility. The volume-phase transition temperature (VPTT) of the PNIPAAm- co-PEG-b-PLLA hydrogels was adjusted using hydrophilic and hydrophobic moieties so that it is ca. 33°C. These hydrogels did not initially show evidence of degradation at 37°C due to physical cross-links of collapsed PNIPAAm. Only after addition of glutathione chain transfer agents (CTA)s to the precursor did the collapsed hydrogels become fully soluble at 37°C. CTAs significantly affected the release kinetics of biomolecules; addition of 1.0 mg/mL glutathione to 3 mM cross-linker accelerated hydrogel degradation, resulting in 100% release in less than 2 days. This work also explored the effect of PEGylation in order to tether biomolecules to the polymer matrix. It was demonstrated that non-site-specific PEGylation can postpone the burst release of solutes (up to 10 days in hydrogels with 0.5 mg/mL glutathione). Cell viability assays showed that at least two 20-minute buffer extraction steps were needed to remove cytotoxic elements from the hydrogels. Clinically-used therapeutic biomolecules LucentisRTM and AvastinRTM were demonstrated to be both stable and bioactive after release form PNIPAAm-co-PEG-b-PLLA hydrogels. The thermo-responsive hydrogels presented here offer a promising platform for the localized delivery of proteins such as recombinant antibodies.

  5. Hydrogel formulation determines cell fate of fetal and adult neural progenitor cells

    Directory of Open Access Journals (Sweden)

    Emily R. Aurand

    2014-01-01

    Full Text Available Hydrogels provide a unique tool for neural tissue engineering. These materials can be customized for certain functions, i.e. to provide cell/drug delivery or act as a physical scaffold. Unfortunately, hydrogel complexities can negatively impact their biocompatibility, resulting in unintended consequences. These adverse effects may be combated with a better understanding of hydrogel chemical, physical, and mechanical properties, and how these properties affect encapsulated neural cells. We defined the polymerization and degradation rates and compressive moduli of 25 hydrogels formulated from different concentrations of hyaluronic acid (HA and poly(ethylene glycol (PEG. Changes in compressive modulus were driven primarily by the HA concentration. The in vitro biocompatibility of fetal-derived (fNPC and adult-derived (aNPC neural progenitor cells was dependent on hydrogel formulation. Acute survival of fNPC benefited from hydrogel encapsulation. NPC differentiation was divergent: fNPC differentiated into mostly glial cells, compared with neuronal differentiation of aNPC. Differentiation was influenced in part by the hydrogel mechanical properties. This study indicates that there can be a wide range of HA and PEG hydrogels compatible with NPC. Additionally, this is the first study comparing hydrogel encapsulation of NPC derived from different aged sources, with data suggesting that fNPC and aNPC respond dissimilarly within the same hydrogel formulation.

  6. Polymer hydrogels as optimized delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Jorge G.S.; Varca, Gustavo H.C.; Ferraz, Caroline C.; Garrido, Gabriela P.; Diniz, Bruna M.; Carvalho, Vinicius S.; Lugao, Ademar B., E-mail: jorgegabriel@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Hydrogels are formed by polymers capable of absorbing large quantities of water. They consist of one or more three-dimensionally structured polymer networks formed by macromolecular chains linked by covalent bonds-crosslinks - and physical interactions. The application of hydrogels, has been widely studied. Biodegradable synthetic or natural polymers such as chitosan, starch and poly-lactic-co-glycolic acid, have properties that allow the development of biodegradable systems for drug and nutraceutics delivery. This study aimed to develop polymeric hydrogels based on polyvinyl alcohol, polyacrylamide and polyvinylpyrrolidone using ionizing radiation in order to develop hydrogels for improved loading and release of compounds. Polymer solutions were solubilized in water and poured into thermoformed packages. After sealing, the material was subjected to γ-irradiation at 25kGy. The samples were assayed by means of mechanical properties, gel fraction and swelling degree. Nanostructure characterization was performed using Flory's equation to determine crosslinking density. The systems developed showed swelling degree and adequate mechanical resistance. The nanostructure evaluation showed different results for each system demonstrating the need of choosing the polymer based on the specific properties of each material. (author)

  7. Polymer hydrogels as optimized delivery systems

    International Nuclear Information System (INIS)

    Batista, Jorge G.S.; Varca, Gustavo H.C.; Ferraz, Caroline C.; Garrido, Gabriela P.; Diniz, Bruna M.; Carvalho, Vinicius S.; Lugao, Ademar B.

    2013-01-01

    Hydrogels are formed by polymers capable of absorbing large quantities of water. They consist of one or more three-dimensionally structured polymer networks formed by macromolecular chains linked by covalent bonds-crosslinks - and physical interactions. The application of hydrogels, has been widely studied. Biodegradable synthetic or natural polymers such as chitosan, starch and poly-lactic-co-glycolic acid, have properties that allow the development of biodegradable systems for drug and nutraceutics delivery. This study aimed to develop polymeric hydrogels based on polyvinyl alcohol, polyacrylamide and polyvinylpyrrolidone using ionizing radiation in order to develop hydrogels for improved loading and release of compounds. Polymer solutions were solubilized in water and poured into thermoformed packages. After sealing, the material was subjected to γ-irradiation at 25kGy. The samples were assayed by means of mechanical properties, gel fraction and swelling degree. Nanostructure characterization was performed using Flory's equation to determine crosslinking density. The systems developed showed swelling degree and adequate mechanical resistance. The nanostructure evaluation showed different results for each system demonstrating the need of choosing the polymer based on the specific properties of each material. (author)

  8. Humidity Induces Changes in the Dimensions of Hydrogel-Coated Wool Yarns

    Directory of Open Access Journals (Sweden)

    Lanlan Wang

    2018-03-01

    Full Text Available Polymeric hydrogel based on acrylic acid (AA and N,N-dimethylacrylamide (DMAA was prepared by photopolymerization reaction, using nano-alumina as the inorganic crosslinker. Hydrogel-coated wool yarns determine their dimensional changes under humidity conditions. Surface morphology of the hydrogel-coated wool yarns was carried out using SEM microscopy. The hydrogel was further characterized by Fourier transformer infrared spectrum (FTIR, gel permeation chromatography (GPC, differential scanning calorimetry (DSC, thermogravimetry (TG and differential thermogravimetry (DTG. This contribution showed that UV-initiated polymerization coating wool yarns can change the functional properties of wool fibers.

  9. Reinforcing the inner phase of the filled hydrogels with CNTs alters drug release properties and human keratinocyte morphology: A study on the gelatin- tamarind gum filled hydrogels.

    Science.gov (United States)

    Maharana, Vivek; Gaur, Deepanjali; Nayak, Suraj K; Singh, Vinay K; Chakraborty, Subhabrata; Banerjee, Indranil; Ray, Sirsendu S; Anis, Arfat; Pal, Kunal

    2017-11-01

    The study reports the synthesis and characterization of gelatin-tamarind gum (TG) based filled hydrogels for drug delivery applications. In this study, three different types of carbon nanotubes (CNTs) were incorporated within the dispersed TG phase of the filled hydrogels. The prepared hydrogels were thoroughly characterised using bright field microscope, FESEM, FTIR spectroscopy, differential scanning calorimeter, and mechanical tester. The swelling and the drug (salicylic acid) release properties of the filled hydrogels were also evaluated. The micrographs revealed the formation of biphasic systems. The internal phase appeared as agglomerates, and the CNTs were confined within the dispersed TG phase. FTIR and XRD studies revealed that CNTs promoted associative interactions among the components of the hydrogel, which promoted the formation of large crystallite size. The mechanical study indicated better resistance to the breakdown of the architecture of the CNT-containing filled hydrogels. Drug release studies, both passive and iontophoretic, suggested that the non-Fickian diffusion of the drug was prevalent during its release from hydrogel matrices. The prepared hydrogels were cytocompatible with human keratinocytes. The results suggested the probable use of such hydrogels in wound healing, tissue engineering and drug delivery applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Biomedical hydrogels biochemistry, manufacture and medical applications

    CERN Document Server

    Rimmer, Steve

    2011-01-01

    Hydrogels are very important for biomedical applications because they can be chemically manipulated to alter and control the hydrogel's interaction with cells and tissues. Their flexibility and high water content is similar to that of natural tissue, making them extremely suitable for biomaterials applications. Biomedical hydrogels explores the diverse range and use of hydrogels, focusing on processing methods and novel applications in the field of implants and prostheses. Part one of this book concentrates on the processing of hydrogels, covering hydrogel swelling behaviour, superabsorbent cellulose-based hydrogels and regulation of novel hydrogel products, as well as chapters focusing on the structure and properties of hydrogels and different fabrication technologies. Part two covers existing and novel applications of hydrogels, including chapters on spinal disc and cartilage replacement implants, hydrogels for ophthalmic prostheses and hydrogels for wound healing applications. The role of hydrogels in imag...

  11. Biomimetic hydrogel loaded with silk and l-proline for tissue engineering and wound healing applications.

    Science.gov (United States)

    Thangavel, Ponrasu; Ramachandran, Balaji; Kannan, Ramya; Muthuvijayan, Vignesh

    2017-08-01

    The aim of this article was to develop silk protein (SF) and l-proline (LP) loaded chitosan-(CS) based hydrogels via physical cross linking for tissue engineering and wound healing applications. Silk fibroin, a biodegradable and biocompatible protein, and l-proline, an important imino acid that is required for collagen synthesis, were added to chitosan to improve the wound healing properties of the hydrogel. Characterization of these hydrogels revealed that CS/SF/LP hydrogels were blended properly and LP incorporated hydrogels showed excellent thermal stability and good surface morphology. Swelling study showed the water holding efficiency of the hydrogels to provide enough moisture at the wound surface. In vitro biodegradation results demonstrated that the hydrogels had good degradation rate in PBS with lysozyme. LP loaded hydrogels showed approximately a twofold increase in antioxidant activity. In vitro cytocompatibility studies using NIH 3T3 L1 cells showed increased cell viability (p Cell adhesion on SF and LP hydrogels were observed using SEM and compared to CS hydrogel. LP incorporation showed 74-78% of wound closure compared to 35% for CS/SF and 3% for CS hydrogels at 48 h. These results suggest that incorporation of LP can significantly accelerate wound healing process compared to pure CS and SF-loaded CS hydrogels. Hence, CS/LP hydrogels could be a potential wound dressing material for the enhanced wound tissue regeneration and repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1401-1408, 2017. © 2016 Wiley Periodicals, Inc.

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

    Science.gov (United States)

    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.

  13. Effective removal of cationic dyes from aqueous solution using gum ghatti-based biodegradable hydrogel

    CSIR Research Space (South Africa)

    Mittal, H

    2015-08-01

    Full Text Available Biodegradable hydrogels of gum ghatti (Gg) with a co-polymer mixture of acrylamide (AAm) and methacrylic acid (MAA) (termed as Gg-cl-P(AAm-co-MAA)) were synthesised by microwave-assisted free radical graft co-polymerisation technique. The hydrogel...

  14. Copolymerization of carbon monoxide and styrene catalyzed by resin-supported palladium polymer

    Directory of Open Access Journals (Sweden)

    2007-02-01

    Full Text Available Polyketone was prepared by the copolymerization of carbon monoxide (CO and styrene (ST catalyzed by o-phenylenediamine resin-supported palladium acetate. Effects of each catalytic system component such as 2,2’-bipyridine, 1,4-quinone and p-toluene-sulphonate on the copolymerization were investigated. The resin-supported catalyst and the copolymerization product were characterized by infrared spectroscopy (IR, differential scanning calorimetry (DSC, thermogravimetry (TG, X-ray photoelectron spectroscopy (XPS, Scanning Electron Microscopy (SEM. Results indicated that the resin-supported catalyst has excellent catalytic property. Furthermore, partial catalytic activity was maintained after the catalyst was used for five times.

  15. Kinetics and thermodynamics of first-order Markov chain copolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Gaspard, P.; Andrieux, D. [Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, Code Postal 231, Campus Plaine, B-1050 Brussels (Belgium)

    2014-07-28

    We report a theoretical study of stochastic processes modeling the growth of first-order Markov copolymers, as well as the reversed reaction of depolymerization. These processes are ruled by kinetic equations describing both the attachment and detachment of monomers. Exact solutions are obtained for these kinetic equations in the steady regimes of multicomponent copolymerization and depolymerization. Thermodynamic equilibrium is identified as the state at which the growth velocity is vanishing on average and where detailed balance is satisfied. Away from equilibrium, the analytical expression of the thermodynamic entropy production is deduced in terms of the Shannon disorder per monomer in the copolymer sequence. The Mayo-Lewis equation is recovered in the fully irreversible growth regime. The theory also applies to Bernoullian chains in the case where the attachment and detachment rates only depend on the reacting monomer.

  16. Antibacterial Modification of Microcrystalline Cellulose by Grafting Copolymerization

    Directory of Open Access Journals (Sweden)

    Ying Liu

    2015-11-01

    Full Text Available Microcrystalline cellulose (MCC has the advantage of a high specific surface area as compared to that of conventional cellulose fibers. In this study the monomer methacrylamide (MAM was used to treat MCC by grafting copolymerization. SEM, FTIR, and solid 13C NMR were used to characterize the morphology and composition of MAM-g-MCC. After the chlorination of MAM-g-MCC with 10% sodium hypochlorite solution, the grafted MCC exhibited antibacterial activity as a result of the formation of N-Cl bonds. The thermal stability, antibacterial ability, and storage stability of chlorinated MAM-g-MCC were also studied. The results showed that the chlorinated MAM-g-MCC had excellent storage stability and could inactivate all S. aureus and E. coli O157:H7 within 10 min.

  17. Radiation initiated copolymerization of allyl alcohol with acrylonitrile

    International Nuclear Information System (INIS)

    Solpan, Dilek; Guven, Olgun

    1996-01-01

    Copolymerization of allyl alcohol (AA) with acrylonitrile (AN) initiated by γ-rays has been investigated to determine the respective reactivity ratios. Three different experimental techniques, namely Fourier Transform Infrared (FTIR), Ultraviolet (UV/vis) and elemental analysis (EA) have been used for the determination of copolymer compositions. Fineman-Ross (FR), Kelen-Tudos (KT), Non-Linear Least Square (NLLS) Analysis and Q-e methods have been applied to the three sets of experimental data. It has been concluded that data obtained from elemental analysis as applied to the Non-Linear Least Square approach gave the most reliable reactivity ratios as 2.09 and 0.40 for acrylonitrile and allyl alcohol, respectively. (Author)

  18. Mussel-Inspired Self-Healing Double-Cross-Linked Hydrogels by Controlled Combination of Metal Coordination and Covalent Cross-Linking

    DEFF Research Database (Denmark)

    Andersen, Amanda; Krogsgaard, Marie; Birkedal, Henrik

    2018-01-01

    a catechol-based hydrogel design that allows for the degree of oxidative covalent cross-linking to be controlled. Double cross-linked hydrogels with tunable stiffness are constructed by adding the oxidizable catechol analogue, tannic acid, to an oxidation-resistant hydrogel construct held together...... by coordination of the dihydroxy functionality of 1-(2'-carboxyethyl)-2-methyl-3-hydroxy-4-pyridinone to trivalent metal ions. By varying the amount of tannic acid, the hydrogel stiffness can be customized to a given application while retaining the self-healing capabilities of the hydrogel's coordination chemical...

  19. Radiation induced graft copolymerization of methyl methacrylate onto chrome-tanned pig skins

    International Nuclear Information System (INIS)

    Pietrucha, K.; Pekala, W.; Kroh, J.

    1981-01-01

    Graft copolymerization of methyl methacrylate (MMA) onto chrome-tanned pig skins was carried out by irradiation with 60 Co γ-rays. The grafted polymethyl methacrylate (PMMA) chains were isolated by acid hydrolysis of the collagen backbone in order to characterize the graft copolymers. Proof of grafting was obtained through the detection of amino acid endgroups in the isolated grafts by reaction with ninhydrin. The grafting yield of MMA in aqueous emulsion was found to be higher than that for pure MMA and MMA in acetone. The degree of grafting increases with increasing monomer concentration in emulsion and reaches maximum at radiation dose ca 15 kGy. The yield of grafting is very high. The present paper reports the physical properties of chrome-tanned pig skins after graft polymerization with MMA in emulsion. Modified leathers are more resistant against water absorption and abrasion in comparison with unmodified ones. They have more uniform structure over the whole surface, greater thickness and stiffness. The mechanism of some of the processes occurring during radiation grafting of MMA in water emulsion on tanned leathers has been also suggested and discussed. (author)

  20. Radiation induced graft copolymerization of methyl methacrylate onto chrome-tanned pig skins

    Energy Technology Data Exchange (ETDEWEB)

    Pietrucha, K.; Pekala, W.; Kroh, J. (Lodz Univ. (Poland))

    1981-01-01

    Graft copolymerization of methyl methacrylate (MMA) onto chrome-tanned pig skins was carried out by irradiation with /sup 60/Co ..gamma..-rays. The grafted polymethyl methacrylate (PMMA) chains were isolated by acid hydrolysis of the collagen backbone in order to characterize the graft copolymers. Proof of grafting was obtained through the detection of amino acid endgroups in the isolated grafts by reaction with ninhydrin. The grafting yield of MMA in aqueous emulsion was found to be higher than that for pure MMA and MMA in acetone. The degree of grafting increases with increasing monomer concentration in emulsion and reaches maximum at radiation dose ca 15 kGy. The yield of grafting is very high. The present paper reports the physical properties of chrome-tanned pig skins after graft polymerization with MMA in emulsion. Modified leathers are more resistant against water absorption and abrasion in comparison with unmodified ones. They have more uniform structure over the whole surface, greater thickness and stiffness. The mechanism of some of the processes occurring during radiation grafting of MMA in water emulsion on tanned leathers has been also suggested and discussed.

  1. Synthesis and Study of Shape-Memory Polymers Selectively Induced by Near-Infrared Lights via In Situ Copolymerization

    Directory of Open Access Journals (Sweden)

    Tianyu Fang

    2017-05-01

    Full Text Available Shape-memory polymers (SMPs selectively induced by near-infrared lights of 980 or 808 nm were synthesized via free radical copolymerization. Methyl methacrylate (MMA monomer, ethylene glycol dimethylacrylate (EGDMA as a cross-linker, and organic complexes of Yb(TTA2AAPhen or Nd(TTA2AAPhen containing a reactive ligand of acrylic acid (AA were copolymerized in situ. The dispersion of the organic complexes in the copolymer matrix was highly improved, while the transparency of the copolymers was negligibly influenced in comparison with the pristine cross-linked PMMA. In addition, the thermal resistance of the copolymers was enhanced with the complex loading, while their glass transition temperature, cross-linking level, and mechanical properties were to some extent reduced. Yb(TTA2AAPhen and Nd(TTA2AAPhen provided the prepared copolymers with selective photothermal effects and shape-memory functions for 980 and 808 nm NIR lights, respectively. Finally, smart optical devices which exhibited localized transparency or diffraction evolution procedures were demonstrated based on the prepared copolymers, owing to the combination of good transparency and selective light wavelength responsivity.

  2. Kinetic investigations of graft copolymerization of sodium styrene sulfonate onto electron beam irradiated poly(vinylidene fluoride) films

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud Nasef, Mohamed, E-mail: mahmoudeithar@fkkksa.utm.m [Institute of Hydrogen Economy, International City Campus, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Chemical Engineering Department, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Saidi, Hamdani [Institute of Hydrogen Economy, International City Campus, Universiti Teknologi Malaysia, Jalan Semarak, 54100 Kuala Lumpur (Malaysia); Chemical Engineering Department, Faculty of Chemical and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Mohd Dahlan, Khairul Zaman [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia)

    2011-01-15

    Graft copolymerization of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films was investigated to find out a simple preparation process for sulfonic acid proton exchange membranes with respect to monomer concentration, absorbed dose, temperature, film thickness and storage time. The reaction order of the monomer concentration and absorbed dose of grafting was found to be 2.84 and 1.20, respectively. The overall activation energy for graft copolymerization reaction was calculated to be 11.36 kJ/mol. The initial rate of grafting was found to decrease with an increase in the film thickness. The trapped radicals in the irradiated PVDF films remained effective in initiating the reaction without considerable loss in grafting level up to 180 days, when stored under -60 {sup o}C. The presence and distribution of polystyrene sulfonate grafts in the obtained membranes were observed by Fourier transform infrared (FTIR) spectroscopic analysis, scanning optical microscope and scanning transmission electron microscopy (STEM) coupled with X-ray energy dispersive (EDX), respectively.

  3. Synthesis and toxicity of poly (2-hydroxyethyl methacrylate-co-acrylamide) hydrogels obtained by gamma photon irradiation

    International Nuclear Information System (INIS)

    Rapado, Manuel; Vernhes, Marioly; Peniche, Carlos

    2016-01-01

    In this paper is reported the obtaining of hydrogels from poly hydroxyethyl methacrylate-co-acrylamide, by simultaneous crosslinking copolymerization from corresponding monomers by gamma photon irradiation. The composition of network chains in the copolymer was estimated from elemental analysis and infrared spectroscopy. Additionally, the toxicity of these materials was tested finding the free acrylamide and biological assay SOS in bacteria. The extracts of washed matrices of copolymers showed low level of free acrylamide. Moreover, they were non toxic on the E. coli cells tested at any time. (author)

  4. High-pressure copolymerization of C 2H 4 and CO

    Science.gov (United States)

    Buback, M.; Tups, H.

    1986-05-01

    Kinetics of the free radical high-pressure copolymerization of ethylene and carbon monoxide using thermal, chemical, and laser-photochemical initiation have been investigated via quantitative infrared and near infrared spectroscopy up to 2300 bar and 513 K. The slow thermal copolymerization is influenced by the formation of metal carbonyls inside the stainless steel cell. With chemical initiation, using 120 ppm oxygen, ethylene and CO polymerize to polyketone without any indication of additional products. The photo-copolymerization induced by an exciplex laser working on the KrF line at 248 nm, has been studied between 486 K and 513 K up to 2300 bar and for CO mole fractions up to 3 percent. Overall quantum yields of about 2000 copolymerizing molecules per one absorbed laser photon are observed.

  5. Radical copolymerization in homogenous medium and emulsion system monomers acrylonitrile/styrene

    Directory of Open Access Journals (Sweden)

    Boussehel H.

    2013-09-01

    Full Text Available This study examines the radical copolymerization in homogeneous and emulsion of the monomer system acrylonitrile/styrene. These copolymers are of great interest to the plastics industry, because they combine the good mechanical properties and implementation provided by the styrene units in the very high solvent resistance and extreme gas impermeability provided by the acrylonitrile units. The properties of a copolymer are directly related to its composition and distribution of monomer units in its macromolecular chains. Based on the reports of the couple reactivity's of monomers (AN/S found in the literature, the objective of the work is to provide theoretical simulation (by analytical and numerical integration of the equation of copolymerization: The kinetics of the reaction copolymerization of AN/S in a homogeneous medium and emulsion (drift composition, azeotropic and the microstructure (distribution of monomer sequences and the glass transition property of the macromolecular chains instant formed throughout the copolymerization reaction.

  6. Polytetrafluorethylene (PTFE) copolymerization with N-N'- dimethyl acrylamide (DMAA) using gamma radiation

    International Nuclear Information System (INIS)

    Queiroz, A.A. de; Higa, O.Z.

    1990-01-01

    The copolymerization of N-N'-dimethylacrylamide monomer with polytetrafluorethylene was made using an insert technique by gamma irradiation. The polimeric surface was characterized by electron microscopy. (author) [pt

  7. Improved Concrete Materials with Hydrogel-Based Internal Curing Agents

    Directory of Open Access Journals (Sweden)

    Matthew J. Krafcik

    2017-11-01

    Full Text Available This research article will describe the design and use of polyelectrolyte hydrogel particles as internal curing agents in concrete and present new results on relevant hydrogel-ion interactions. When incorporated into concrete, hydrogel particles release their stored water to fuel the curing reaction, resulting in reduced volumetric shrinkage and cracking and thus increasing concrete service life. The hydrogel’s swelling performance and mechanical properties are strongly sensitive to multivalent cations that are naturally present in concrete mixtures, including calcium and aluminum. Model poly(acrylic acid(AA-acrylamide(AM-based hydrogel particles with different chemical compositions (AA:AM monomer ratio were synthesized and immersed in sodium, calcium, and aluminum salt solutions. The presence of multivalent cations resulted in decreased swelling capacity and altered swelling kinetics to the point where some hydrogel compositions displayed rapid deswelling behavior and the formation of a mechanically stiff shell. Interestingly, when incorporated into mortar, hydrogel particles reduced mixture shrinkage while encouraging the formation of specific inorganic phases (calcium hydroxide and calcium silicate hydrate within the void space previously occupied by the swollen particle.

  8. Reusable self-healing hydrogels realized via in situ polymerization.

    Science.gov (United States)

    Vivek, Balachandran; Prasad, Edamana

    2015-04-09

    In this work, a self-healing hydrogel has been prepared using in situ polymerization of acrylic acid and acrylamide in the presence of glycogen. The hydrogel was characterized using NMR, SEM, FT-IR, rheology, and dynamic light scattering (DLS) studies. The developed hydrogel exhibits self-healing properties at neutral pH, high swelling ability, high elasticity, and excellent mechanical strength. The hydrogel exhibits modulus values (G', G″) as high as 10(6) Pa and shows an exceptionally high degree of swelling ratio (∼3.5 × 10(3)). Further, the polymer based hydrogel adsorbs toxic metal ions (Cd(2+), Pb(2+), and Hg(2+)) and organic dyes (methylene blue and methyl orange) from contaminated water with remarkable efficiency (90-98%). The mechanistic analysis indicated the presence of pseudo-second-order reaction kinetics. The reusability of the hydrogel has been demonstrated by repeating the adsorption-desorption process over five cycles with identical results in the adsorption efficiency.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mahmud, Maznah [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor (Malaysia); Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia); Daik, Rusli [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor (Malaysia); Adam, Zainah [Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia)

    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.

  10. Simulation of emulsion copolymerization reactions in a continuous pulsed sieve-plate column reactor

    OpenAIRE

    C. Sayer; R. Giudici

    2004-01-01

    This work addressed the viability of using a pulsed sieve-plate column reactor to carry out continuous vinyl acetate/butyl acrylate emulsion copolymerization reactions. A rigorous mathematical model of emulsion copolymerization reactions in a tubular reactor with axial dispersion was used for this purpose. Operational conditions were defined to attain high monomer conversions at the reactor outlet in a relatively short residence time and, at the same time, produce a copolymer with a more homo...

  11. Simulation of emulsion copolymerization reactions in a continuous pulsed sieve-plate column reactor

    Directory of Open Access Journals (Sweden)

    Sayer C.

    2004-01-01

    Full Text Available This work addressed the viability of using a pulsed sieve-plate column reactor to carry out continuous vinyl acetate/butyl acrylate emulsion copolymerization reactions. A rigorous mathematical model of emulsion copolymerization reactions in a tubular reactor with axial dispersion was used for this purpose. Operational conditions were defined to attain high monomer conversions at the reactor outlet in a relatively short residence time and, at the same time, produce a copolymer with a more homogeneous composition.

  12. Development of (acrylic acid/ polyethylene glycol)-zinc oxide mucoadhesive nanocomposites for buccal administration of propranolol HCl

    Science.gov (United States)

    Mahmoud, Ghada A.; Ali, Amr El-Hag; Raafat, Amany I.; Badawy, Nagwa A.; Elshahawy, Mai. F.

    2018-06-01

    A series of mucoadhesive nanocomposites with self disinfection properties composed of acrylic acid, polyethylene glycol and ZnO nanoparticles (AAc/PEG)-ZnO were developed for localized buccal Propranolol HCl delivery. γ-irradiation as a clean tool for graft copolymerization process was used for the preparation of (AAc/PEG) hydrogels. In suite precipitation technique was used for ZnO nanoparticles immobilization within (AAc/PEG) hydrogels. The developed (AAc/PEG)-ZnO nanocomposites were characterized by X-ray diffraction (XRD), UV-Vis spectrophotometer, energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) to confirm the success of ZnO nanoparticles formation within the (AAc/PEG) matrices. The presence of ZnO nanoparticles improves the thermal stability as indicated using thermogravimetric analysis (TGA). The mucoadhesion characteristics such as hydration degree, surface pH, and mucoadhesive strength were evaluated in artificial saliva solution. The self disinfection property of the developed (AAc/PEG)-ZnO nanocomposites was investigated by examining their resistance to pathogenic microorganisms such as Staphylococcus aureus, Bacillus subtilis, and Escherichia coli using disc diffusion method. The release of Propranolol -HCl drug in artificial saliva was found to obey a non-Fickian diffusion mechanism. The obtained results suggests that (AAc/PEG)-ZnO nanocomposites could be used as mucoadhesive carrier for buccal drug delivery with efficient antibacterial properties.

  13. Functional elastic hydrogel as recyclable membrane for the adsorption and degradation of methylene blue.

    Directory of Open Access Journals (Sweden)

    Song Bao

    Full Text Available 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.

  14. Targeted Drug Delivery in the Suprachoroidal Space by Swollen Hydrogel Pushing

    Science.gov (United States)

    Jung, Jae Hwan; Desit, Patcharin; Prausnitz, Mark R.

    2018-01-01

    Purpose The purpose is to target model drug particles to the posterior region of the suprachoroidal space (SCS) of the eye controlled via pushing by hydrogel swelling. Methods A particle formulation containing 1% hyaluronic acid (HA) with fluorescent polymer particles and a hydrogel formulation containing 4% HA were introduced in a single syringe as two layers without mixing, and injected sequentially into the SCS of the rabbit eye ex vivo and in vivo using a microneedle. Distribution of particles in the eye was determined by microscopy. Results During injection, the particle formulation was pushed toward the middle of the SCS by the viscous hydrogel formulation, but less than 12% of particles reached the posterior SCS. After injection, the particle formulation was pushed further toward the macula and optic nerve in the posterior SCS by hydrogel swelling and spreading. Heating the eye to 37°C, or injecting in vivo decreased viscosity and mechanical strength of the hydrogel, thereby allowing it to swell and flow further in the SCS. A high salt concentration (9% NaCl) in the hydrogel formulation further increased hydrogel swelling due to osmotic flow into the hydrogel. In this way, up to 76% of particles were delivered to the posterior SCS from an injection made near the limbus. Conclusions This study shows that model drug particles can be targeted to the posterior SCS by HA hydrogel swelling and pushing without particle functionalization or administering external driving forces. PMID:29677369

  15. Targeted Drug Delivery in the Suprachoroidal Space by Swollen Hydrogel Pushing.

    Science.gov (United States)

    Jung, Jae Hwan; Desit, Patcharin; Prausnitz, Mark R

    2018-04-01

    The purpose is to target model drug particles to the posterior region of the suprachoroidal space (SCS) of the eye controlled via pushing by hydrogel swelling. A particle formulation containing 1% hyaluronic acid (HA) with fluorescent polymer particles and a hydrogel formulation containing 4% HA were introduced in a single syringe as two layers without mixing, and injected sequentially into the SCS of the rabbit eye ex vivo and in vivo using a microneedle. Distribution of particles in the eye was determined by microscopy. During injection, the particle formulation was pushed toward the middle of the SCS by the viscous hydrogel formulation, but less than 12% of particles reached the posterior SCS. After injection, the particle formulation was pushed further toward the macula and optic nerve in the posterior SCS by hydrogel swelling and spreading. Heating the eye to 37°C, or injecting in vivo decreased viscosity and mechanical strength of the hydrogel, thereby allowing it to swell and flow further in the SCS. A high salt concentration (9% NaCl) in the hydrogel formulation further increased hydrogel swelling due to osmotic flow into the hydrogel. In this way, up to 76% of particles were delivered to the posterior SCS from an injection made near the limbus. This study shows that model drug particles can be targeted to the posterior SCS by HA hydrogel swelling and pushing without particle functionalization or administering external driving forces.

  16. Design and synthesis of an amphiphilic graft hydrogel having a hydrophobic domain formed by multiple interactions

    Energy Technology Data Exchange (ETDEWEB)

    Nitta, Kyohei [Department of Life and Functional Material Science, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada, Kobe 658-8501 (Japan); Japan Society for the Promotion of Science (DC1), Ichibancho, Chiyoda, Tokyo 102-8471 (Japan); Kimoto, Atsushi [Department of Chemistry of Functional Molecules, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada, Kobe 658-8501 (Japan); Watanabe, Junji, E-mail: junjiknd@konan-u.ac.jp [Department of Chemistry of Functional Molecules, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada, Kobe 658-8501 (Japan)

    2016-11-01

    A novel hydrogel having hydrophobic oligo segments and hydrophilic poly(acrylamidoglycolic acid) (PAGA) as pH responsive polymer segments was designed and synthesized to be used as a soft biomaterial. Poly(trimethylene carbonate) (PTMC) as the side chain, for which the degrees of polymerization were 9, 19, and 49, and the composition ratios were 1, 5, and 10 mol%, was used as the oligo segment in the hydrogel. The swelling ratio of the hydrogel was investigated under various changes in conditions such as pH, temperature, and hydrogen bonding upon urea addition. Under pH 2–11 conditions, the graft gel reversibly swelled and shrank due to the effect of PAGA main chain. The interior morphology and skin layer of the hydrogel was observed by a scanning electron microscope. The hydrogel composed of PAGA as the hydrophilic polymer backbone had a sponge-like structure, with a pore size of approximately 100 μm. On the other hand, upon increasing the ratio of trimethylene carbonate (TMC) units in the hydrogel, the pores became smaller or disappeared. Moreover, thickness of the skin layer significantly increased with the swelling ratio depended on the incorporation ratios of the PTMC macromonomer. Molecular incorporation in the hydrogel was evaluated using a dye as a model drug molecule. These features would play an important role in drug loading. Increasing the ratio of TMC units favored the adsorption of the dye and activation of the incorporation behavior. - Highlights: • Hydrogen bonding and hydrophobic interaction are dominant factor for forming hydrogels. • Hydrogel properties were tuned by changing in graft length and macromonomer content in feed. • The resulting graft gel could encapsulate and retain organic dye in the hydrogel. • Poly(trimethylene carbonate) segment in the hydrogel was dominant unit for hydrogel.

  17. Design and synthesis of an amphiphilic graft hydrogel having a hydrophobic domain formed by multiple interactions

    International Nuclear Information System (INIS)

    Nitta, Kyohei; Kimoto, Atsushi; Watanabe, Junji

    2016-01-01

    A novel hydrogel having hydrophobic oligo segments and hydrophilic poly(acrylamidoglycolic acid) (PAGA) as pH responsive polymer segments was designed and synthesized to be used as a soft biomaterial. Poly(trimethylene carbonate) (PTMC) as the side chain, for which the degrees of polymerization were 9, 19, and 49, and the composition ratios were 1, 5, and 10 mol%, was used as the oligo segment in the hydrogel. The swelling ratio of the hydrogel was investigated under various changes in conditions such as pH, temperature, and hydrogen bonding upon urea addition. Under pH 2–11 conditions, the graft gel reversibly swelled and shrank due to the effect of PAGA main chain. The interior morphology and skin layer of the hydrogel was observed by a scanning electron microscope. The hydrogel composed of PAGA as the hydrophilic polymer backbone had a sponge-like structure, with a pore size of approximately 100 μm. On the other hand, upon increasing the ratio of trimethylene carbonate (TMC) units in the hydrogel, the pores became smaller or disappeared. Moreover, thickness of the skin layer significantly increased with the swelling ratio depended on the incorporation ratios of the PTMC macromonomer. Molecular incorporation in the hydrogel was evaluated using a dye as a model drug molecule. These features would play an important role in drug loading. Increasing the ratio of TMC units favored the adsorption of the dye and activation of the incorporation behavior. - Highlights: • Hydrogen bonding and hydrophobic interaction are dominant factor for forming hydrogels. • Hydrogel properties were tuned by changing in graft length and macromonomer content in feed. • The resulting graft gel could encapsulate and retain organic dye in the hydrogel. • Poly(trimethylene carbonate) segment in the hydrogel was dominant unit for hydrogel.

  18. Influence of pH on Cr(VI) ions removal from aqueous solutions using carboxymethyl cellulose-based hydrogel as adsorbent

    Science.gov (United States)

    Anah, L.; Astrini, N.

    2017-03-01

    The major problem in heavy metal pollution is that these metals are not biodegradable and accordingly accumulate in the bodies of living organisms, causing dangerous diseases and serious cell disorder. According to World Health Organization (WHO), the long term exposure of Cr(VI) levels of over 0.1 ppm causes respiratory problems, liver and kidney damage, and carcinogenicity.Due to its easy operation and of various cheap adsorbents development, adsorption has been proved to be efficient and most economically attractive technique and feasible to the removal of toxic heavy metal from wastewater. The study aimed to report the removal of Cr(VI) ions from aqueous solutions through adsorption process using carboxymethyl cellulose-graft-poly(acrylic acid) (CMC-g-PAA) hydrogel as adsorbent.Effect of pH was studied to remove hexavalent chromium.Graft copolymerization of poly(acrylic acid) onto carboxymethyl cellulose was carried out in the presence of benzoyl peroxide redox initiator and methylenbisacrylamide as crosslinker agent. Batch experiments were carried out to investigate the effects ofinitial pH.The adsorption of Cr(VI) ions as a function of pH was conducted in the initial pH range of 1 to 8. The results indicated that acidic pH strongly favored the adsorption. The optimum pH for adsorption of Cr(VI) ranged from 1 to 3, and the maximum uptake of Cr(VI) from the solution was 6.53 mg/g at pH 1 and 30°C. FTIR spectroscopy, SEM analyses were performed on the adsorbent before and after Cr(VI) binding. All analyses confirmed the complexation of Cr(VI) ions on the adsorbent.

  19. Preparation of metal ion exchange resin by radiation-induced graft copolymerization

    International Nuclear Information System (INIS)

    Nakase, Yoshiaki; Akasaka, Nobuhiro.

    1982-06-01

    Radiation-induced graft copolymerization of 2-acrylamide-2-methyl propane sulfonic acid (AMPS) onto polyvinylchloride (PVC) and polyvinylidene chloride resin (PVD) was investigated in the water-acetone system and their adsorptive activities to metal ion were also examined. In the case of PVC, the degree of grafting increased with the increase of acetone content, but the adsorptive activity to metal ions (mainly lithic ion) became maximum in the system with water/acetone of 2/3. Grafted PVC prepared at about 35 0 C and at a higher concentration of AMPS showed higher adsorption activity than the other cases. In the case of PVD, a similar result was obtained with the case of PVC except the temperature dependence and effect of swelling agent. Polymerizations at temperatures of 35 and 50 0 C showed no effect on the degree of grafting, and the usage of a swelling agent was quite effective to the adsorptive activity. Glass transition temperature of the grafted copolymer was the same as that of original polymer, and their thermal stability was confirmed up to the temperature at which homopolymer of AMPS decomposed, about 180 0 C. (author)

  20. Mechanistic aspects of the metal catalyzed alternating copolymerization of epoxides and carbon monoxide.

    Science.gov (United States)

    Allmendinger, Markus; Molnar, Ferenc; Zintl, Manuela; Luinstra, Gerrit A; Preishuber-Pflügl, Peter; Rieger, Bernhard

    2005-09-05

    The cobalt-catalyzed alternating copolymerization of epoxides and CO is a novel, direct approach to aliphatic polyesters, such as poly(hydroxybutyrate) (PHB). This reaction was found to be catalyzed by Ph3Si[Co(CO)4] (4) and pyridine affording in a first step the stable mono-insertion product Ph3Si-O-CH(CH3)-CH2-CO-Co(CO)4 (5). However, a profound mechanistic understanding, especially of the role of pyridine as the key component for the polymerization reaction was missing. ATR-IR online monitoring under catalytic conditions and DFT calculations were used to show that an acylpyridinium cation is formed by cleavage of the cobalt-acyl bond of 5 in the presence of pyridine. The Lewis acid thus generated activates the next incoming epoxide monomer for ring opening through [Co(CO)4]-. The catalytic cycle is completed by a subsequent CO insertion in the new cobalt-alkyl bond. The calculations are used to explore the energetic hypersurface of the polymerization reaction and are complemented by extended experimental investigations that also support the mechanistic hypotheses.

  1. In vivo non-invasive optical imaging of temperature-sensitive co-polymeric nanohydrogel

    Science.gov (United States)

    Chen, Haiyan; Zhang, Jian; Qian, Zhiyu; Liu, Fei; Chen, Xinyang; Hu, Yuzhu; Gu, Yueqing

    2008-05-01

    Assessment of hyperthermia in pathological tissue is a promising strategy for earlier diagnosis of malignant tumors. In this study, temperature-sensitive co-polymeric nanohydrogel poly(N-isopropylacrylamide-co-acrylic acid) (PNIPA-co-AA) was successfully synthesized by the precipitation polymerization method. The diameters of nanohydrogels were controlled to be less than 100 nm. Also the lower critical solution temperature (LCST, 40 °C) was manipulated above physiological temperature after integration of near-infrared (NIR) organic dye (heptamethine cyanine dye, HMCD) within its interior cores. NIR laser light (765 nm), together with sensitive charge coupled device (CCD) cameras, were designed to construct an NIR imaging system. The dynamic behaviors of PNIPA-co-AA-HMCD composites in denuded mice with or without local hyperthermia treatment were real-time monitored by an NIR imager. The results showed that the PNIPA-co-AA-HMCD composites accumulated in the leg treated with local heating and diffused much slower than that in the other leg without heating. The results demonstrated that the temperature-responsive PNIPA-co-AA-HMCD composites combining with an NIR imaging system could be an effective temperature mapping technique, which provides a promising prospect for earlier tumor diagnosis and thermally related therapeutic assessment.

  2. In vivo non-invasive optical imaging of temperature-sensitive co-polymeric nanohydrogel

    International Nuclear Information System (INIS)

    Chen Haiyan; Hu Yuzhu; Zhang Jian; Liu Fei; Chen Xinyang; Gu Yueqing; Qian Zhiyu

    2008-01-01

    Assessment of hyperthermia in pathological tissue is a promising strategy for earlier diagnosis of malignant tumors. In this study, temperature-sensitive co-polymeric nanohydrogel poly(N-isopropylacrylamide-co-acrylic acid) (PNIPA-co-AA) was successfully synthesized by the precipitation polymerization method. The diameters of nanohydrogels were controlled to be less than 100 nm. Also the lower critical solution temperature (LCST, 40 deg. C) was manipulated above physiological temperature after integration of near-infrared (NIR) organic dye (heptamethine cyanine dye, HMCD) within its interior cores. NIR laser light (765 nm), together with sensitive charge coupled device (CCD) cameras, were designed to construct an NIR imaging system. The dynamic behaviors of PNIPA-co-AA-HMCD composites in denuded mice with or without local hyperthermia treatment were real-time monitored by an NIR imager. The results showed that the PNIPA-co-AA-HMCD composites accumulated in the leg treated with local heating and diffused much slower than that in the other leg without heating. The results demonstrated that the temperature-responsive PNIPA-co-AA-HMCD composites combining with an NIR imaging system could be an effective temperature mapping technique, which provides a promising prospect for earlier tumor diagnosis and thermally related therapeutic assessment

  3. Recent Developments in Thiolated Polymeric Hydrogels for Tissue Engineering Applications.

    Science.gov (United States)

    Gajendiran, Mani; Rhee, Jae-Sung; Kim, Kyobum

    2018-02-01

    This review focuses on the recent strategy in the preparation of thiolated polymers and fabrication of their hydrogel matrices. The mechanism involved in the synthesis of thiolated polymers and fabrication of thiolated polymer hydrogels is exemplified with suitable schematic representations reported in the recent literature. The 2-iminothiolane namely "Traut's reagent" has been widely used for effectively thiolating the natural polymers such as collagen and gelatin, which contain free amino group in their backbone. The free carboxylic acid group containing polymers such as hyaluronic acid and heparin have been thiolated by using the bifunctional molecules such as cysteamine and L-cysteine via N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling reaction. The degree of thiolation in the polymer chain has been widely determined by using Ellman's assay method. The thiolated polymer hydrogels are prepared by disulfide bond formation (or) thiol-ene reaction (or) Michael-type addition reaction. The thiolated polymers such as thiolated gelatin are reacted with polyethylene glycol diacrylate for obtaining interpenetrating polymer network hydrogel scaffolds. Several in vitro cell culture experiments indicate that the developed thiolated polymer hydrogels exhibited biocompatibility and cellular mimicking properties. The developed hydrogel scaffolds efficiently support proliferation and differentiation of various cell types. In the present review article, the thiol-functionalized protein-based biopolymers, carbohydrate-based polymers, and some synthetic polymers have been covered with recently published research articles. In addition, the usage of new thiolated nanomaterials as a crosslinking agent for the preparation of three-dimensional tissue-engineered hydrogels is highlighted.

  4. Recombinant human serum albumin hydrogel as a novel drug delivery vehicle

    International Nuclear Information System (INIS)

    Hirose, Masaaki; Tachibana, Akira; Tanabe, Toshizumi

    2010-01-01

    Serum albumin acts as a physiological carrier for various compounds including drugs. A hydrogel consisting of recombinant human serum albumin (rHSA) was prepared to take advantage of drug binding ability of albumin for a sustained drug release carrier. The hydrogel was prepared by mixing rHSA and dithiothreitol and casted to a polystyrene mold. Hydrogel formation was thought to occur through the intermolecular interaction of the hydrophobic groups by protein denaturation. The release of sodium benzoate and salicylic acid from the hydrogel completed in 2 h, while warfarin release continued for 24 h. The total amounts of the drugs released from 100 mg of 15 and 5% rHSA hydrogel were 2.3 and 1.4 μmol for warfarin, 1.4 and 1.1 μmol for salicylic acid and 0.9 and 0.9 μmol for sodium benzoate. These results reflected the order of the binding ability of drugs for intact albumin indicating that the drug binding ability of HSA still remained after the hydrogel formation. However, fibroblast cells attached and proliferated well on the hydrogel, indicating that denaturation of rHSA proceeded to the extent to allow the cell attachment. The present rHSA hydrogel might be suitable for a sustained release carrier of drugs having affinity for albumin.

  5. Recombinant human serum albumin hydrogel as a novel drug delivery vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, Masaaki, E-mail: Hirose.Masaaki@mh.mt-pharma.co.jp [Advanced Medical Research Laboratory, Research Division, Mitsubishi Tanabe Pharma Corporation, 3-16-89 Kashima, Yodogawa-ku, Osaka 532-8505 (Japan); Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Tachibana, Akira; Tanabe, Toshizumi [Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)

    2010-06-15

    Serum albumin acts as a physiological carrier for various compounds including drugs. A hydrogel consisting of recombinant human serum albumin (rHSA) was prepared to take advantage of drug binding ability of albumin for a sustained drug release carrier. The hydrogel was prepared by mixing rHSA and dithiothreitol and casted to a polystyrene mold. Hydrogel formation was thought to occur through the intermolecular interaction of the hydrophobic groups by protein denaturation. The release of sodium benzoate and salicylic acid from the hydrogel completed in 2 h, while warfarin release continued for 24 h. The total amounts of the drugs released from 100 mg of 15 and 5% rHSA hydrogel were 2.3 and 1.4 {mu}mol for warfarin, 1.4 and 1.1 {mu}mol for salicylic acid and 0.9 and 0.9 {mu}mol for sodium benzoate. These results reflected the order of the binding ability of drugs for intact albumin indicating that the drug binding ability of HSA still remained after the hydrogel formation. However, fibroblast cells attached and proliferated well on the hydrogel, indicating that denaturation of rHSA proceeded to the extent to allow the cell attachment. The present rHSA hydrogel might be suitable for a sustained release carrier of drugs having affinity for albumin.

  6. Ionic membranes obtained by radiation-induced graft copolymerization, I-preparation. Vol. 3

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Rehim, H A; Hegazy, E A [National Center for Radiation and Technology, Atomic Energy Authority, Cairo, (Egypt); Ali, A M.I.; Nowier, H G; Aly, H F [Hot Laboratories Center, atomic Energy Authority, Cairo, (Egypt)

    1996-03-01

    A study has been made on the preparation of ionic membranes by radiation-induced graft copolymerization of acrylic acid (AAC) onto low density polyethylene (LDPE) films. The Suitable conditions at which the grafting proceeds homogeneously were determined. To minimize the homo polymerization of AAC during irradiation process different types of inhibitors were investigated to find that the addition of Fe Cl{sub 3} (1.5 Wt%) effectively reduced such process when compared with other inhibitors used. The suitable diluent for this grafting system is found to be distilled water, methanol and methanol water mixture. The effect of diluent mixture composition, irradiation time, addition of mineral or organic acid and metal chlorides on the grafting yield and its homogeneity in the graft copolymer was determined. It was observed that the grafting yield increased as the content of water increased in MeOH/H{sub 2} O mixture. The addition of oxalic acid to the reaction medium enhanced the grafting process, however, the addition of HCl or H{sub 2} S O{sub 4} resulted in a more homogeneous grafting. The same effect was also observed when metal salts; namely N H{sub 4} Cl, NaCl and Cu Cl{sub 2} were added and resulted in homogeneous grafted membranes. The swelling and permeability of the grafted films prepared were also investigated. Results obtained in this study showed a great promise for the possible practical use of such prepared graft copolymers as a good hydrophilic membrane. The possibility of its use as an ion-exchange membrane for metal waste will be considered.4 figs., 5 tabs.

  7. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

    International Nuclear Information System (INIS)

    Mu Bin; Zhao Mingfei; Liu Peng

    2008-01-01

    Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results

  8. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Mu Bin; Zhao Mingfei; Liu Peng [Lanzhou University, State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering (China)], E-mail: pliu@lzu.edu.cn

    2008-05-15

    Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results.

  9. Hydrogel nanoparticle based immunoassay

    Science.gov (United States)

    Liotta, Lance A; Luchini, Alessandra; Petricoin, Emanuel F; Espina, Virginia

    2015-04-21

    An immunoassay device incorporating porous polymeric capture nanoparticles within either the sample collection vessel or pre-impregnated into a porous substratum within fluid flow path of the analytical device is presented. This incorporation of capture particles within the immunoassay device improves sensitivity while removing the requirement for pre-processing of samples prior to loading the immunoassay device. A preferred embodiment is coreshell bait containing capture nanoparticles which perform three functions in one step, in solution: a) molecular size sieving, b) target analyte sequestration and concentration, and c) protection from degradation. The polymeric matrix of the capture particles may be made of co-polymeric materials having a structural monomer and an affinity monomer, the affinity monomer having properties that attract the analyte to the capture particle. This device is useful for point of care diagnostic assays for biomedical applications and as field deployable assays for environmental, pathogen and chemical or biological threat identification.

  10. Chitosan-containing hydrogel wound dressings prepared by radiation technique

    International Nuclear Information System (INIS)

    Mozalewska, Wiktoria; Czechowska-Biskup, Renata; Olejnik, Alicja K.; Wach, Radoslaw A.; Ulański, Piotr; Rosiak, Janusz M.

    2017-01-01

    The aim of the study was to develop an antimicrobial hydrogel wound dressing by means of radiation-initiated crosslinking of hydrophilic polymers, i.e. by well-established technology comprising gel manufacturing and its sterilization in one process. The approach included admixture of chitosan of relatively low molecular weight dissolved in lactic acid (LA) into the initial regular components of the conventional hydrogel dressing based on poly(N-vinyl pyrrolidone) (PVP) and agar. Molecular weight of chitosan was regulated by radiation-initiated degradation in the range of 39–132 kg mol −1 . Optimum total concentration of LA in the resultant hydrogel dressing was evaluated as 0.05 mol dm −3 , that is ca. 0.5%. Presence of LA in the system influenced essential radiation and technological parameters of hydrogel manufacturing. The setting temperature of the pre-hydrogel mixture, resulting from agar ability to congeal, was reduced with LA concentration, yet remained significantly above the room temperature. 0.5% of chitosan was effectively dissolved in aqueous solution of lactic acid due to its pH (lower than 5.5). Radiation parameters of PVP crosslinking in the presence of LA, as determined with generalized Charlesby–Pinner equation, were reflected in slight reduction of the maximum gel fraction and increase in gelation dose and in the factor comparing yields of scission to crosslinking. Nevertheless, essentially physical characteristics of the hydrogel was not affected, except for somewhat increased water uptake capacity, what in turn improves functionality of the dressing as extensive exudate for the wound can be efficiently absorbed. Preliminary microbiological studies showed antimicrobial character of the chitosan-containing hydrogel towards Gram-positive bacterial strain. - Highlights: • Radiation synthesis of bioactive hydrogel wound dressing based on PVP. • Sol-gel analysis, radiation yield of crosslinking and degradation, gel fraction.

  11. Ionic Conductivity of Polyelectrolyte Hydrogels.

    Science.gov (United States)

    Lee, Chen-Jung; Wu, Haiyan; Hu, Yang; Young, Megan; Wang, Huifeng; Lynch, Dylan; Xu, Fujian; Cong, Hongbo; Cheng, Gang

    2018-02-14

    Polyelectrolytes have many important functions in both living organisms and man-made applications. One key property of polyelectrolytes is the ionic conductivity due to their porous networks that allow the transport of water and small molecular solutes. Among polyelectrolytes, zwitterionic polymers have attracted huge attention for applications that involve ion transport in a polyelectrolyte matrix; however, it is still unclear how the functional groups of zwitterionic polymer side chains affect their ion transport and swelling properties. In this study, zwitterionic poly(carboxybetaine acrylamide), poly(2-methacryloyloxyethyl phosphorylcholine), and poly(sulfobetaine methacrylate) hydrogels were synthesized and their ionic conductivity was studied and compared to cationic, anionic, and nonionic hydrogels. The change of the ionic conductivity of zwitterionic and nonionic hydrogels in different saline solutions was investigated in detail. Zwitterionic hydrogels showed much higher ionic conductivity than that of the widely used nonionic poly(ethylene glycol) methyl ether methacrylate hydrogel in all tested solutions. For both cationic and anionic hydrogels, the presence of mobile counterions led to high ionic conductivity in low salt solutions; however, the ionic conductivity of zwitterionic hydrogels surpassed that of cationic and ionic hydrogels in high salt solutions. Cationic and anionic hydrogels showed much higher water content than that of zwitterionic hydrogels in deionized water; however, the cationic hydrogels shrank significantly with increasing saline concentration. This work provides insight into the effects of polyelectrolyte side chains on ion transport. This can guide us in choosing better polyelectrolytes for a broad spectrum of applications, including bioelectronics, neural implants, battery, and so on.

  12. Design of multimodal degradable hydrogels for controlled therapeutic delivery

    Science.gov (United States)

    Kharkar, Prathamesh Madhav

    thiol exchange reaction facilitated rapid and responsive protein release in the presence of GSH. A photolabile o-nitrobenzyl ether group (o-NB) was subsequently incorporated within the PEG-based, gel-forming monomers to demonstrate cargo release triggered by exogenous stimuli for patient-specific therapies. Upon the application of cytocompatible doses of light, the photolabile o-NB linkage underwent irreversible cleavage yielding ketone and carboxylic acid-based cleavage products. Hydrogel degradation kinetics was characterized in response to externally applied cytocompatible light or GSH in aqueous microenvironments. By incorporating a photodegradable o-nitrobenzyl ether group, a thiol-sensitive succinimide thioether linkage, and ester linkages within the hydrogels, we demonstrated unique control over degradation via surface erosion or bulk degradation mechanisms, respectively, with degradation rate constants ranging from 10-1 min-1 to 10-4 min-1. As a proof of concept, the controlled release of nanobeads from the hydrogel was demonstrated in a preprogrammed and stimuli-responsive fashion. The multimodal degradable hydrogels were then investigated for the local controlled release of small molecular weight proteins, which are of interest for regulating various cellular functions and fates in vivo. Low molecular weight heparin, a highly sulfated polysaccharide was incorporated within the hydrogel network by Michael-type reaction due to its affinity with biologics such as growth factors and immunomodulatory proteins. Incorporation of reduction-sensitive linkages resulted in 2.3 fold differences in the release profile of fibroblast growth factor-2 (FGF-2) in the presence of GSH compared to non-reducing microenvironment. Bioactivity of released FGF-2 was comparable to pristine FGF-2, indicating the ability of the hydrogel to retain bioactivity of cargo molecules during encapsulation and release. Further, preliminary in vivo studies demonstrated control over hydrogel

  13. Synthesis and application of intelligent hydrogels

    International Nuclear Information System (INIS)

    Kaetsu, I.; Uchida, K.; Sutani, K.; Nakayama, H.; Tamori, A.

    2000-01-01

    The authors have studied synthesis and application of stimule-sensitive and responsive hydrogels. In this report, two kinds of investigations were carried out on the intelligent hydrogels and the applications with radiation techniques. 1. Synthesis of temperature responsive sol-gel transition polymer and the application to drug delivery systems. Polysopropyl acrylamide is a typical temperature responsive polymers and the copolymers show broad variation of LCST (sol-gel transition temperature). The various copolymers of isopropyl acrylamide were synthesized by UV or radiation. 2. Surface curing of pH and electric field responsive hydrogel and the application to drug delivery systems. Electrolyte monomers such as acrylic acid was coated on the surface of polymer membrane (porous or non-porous) including drugs, and cured by UV or radiation various enzymes were immobilized in the coating layer in many cases. The product showed pH, electro-field and substrate responsive releases of model drug under on-off switching of environmental conditions. (J.P.N.)

  14. Synthesis and application of intelligent hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Kaetsu, I.; Uchida, K.; Sutani, K.; Nakayama, H.; Tamori, A. [Kinki Univ., Higashi-Osaka, Osaka (Japan). Faculty of Science and Technology

    2000-03-01

    The authors have studied synthesis and application of stimule-sensitive and responsive hydrogels. In this report, two kinds of investigations were carried out on the intelligent hydrogels and the applications with radiation techniques. 1. Synthesis of temperature responsive sol-gel transition polymer and the application to drug delivery systems. Polysopropyl acrylamide is a typical temperature responsive polymers and the copolymers show broad variation of LCST (sol-gel transition temperature). The various copolymers of isopropyl acrylamide were synthesized by UV or radiation. 2. Surface curing of pH and electric field responsive hydrogel and the application to drug delivery systems. Electrolyte monomers such as acrylic acid was coated on the surface of polymer membrane (porous or non-porous) including drugs, and cured by UV or radiation various enzymes were immobilized in the coating layer in many cases. The product showed pH, electro-field and substrate responsive releases of model drug under on-off switching of environmental conditions. (J.P.N.)

  15. A Self-Folding Hydrogel In Vitro Model for Ductal Carcinoma.

    Science.gov (United States)

    Kwag, Hye Rin; Serbo, Janna V; Korangath, Preethi; Sukumar, Saraswati; Romer, Lewis H; Gracias, David H

    2016-04-01

    A significant challenge in oncology is the need to develop in vitro models that accurately mimic the complex microenvironment within and around normal and diseased tissues. Here, we describe a self-folding approach to create curved hydrogel microstructures that more accurately mimic the geometry of ducts and acini within the mammary glands, as compared to existing three-dimensional block-like models or flat dishes. The microstructures are composed of photopatterned bilayers of poly (ethylene glycol) diacrylate (PEGDA), a hydrogel widely used in tissue engineering. The PEGDA bilayers of dissimilar molecular weights spontaneously curve when released from the underlying substrate due to differential swelling ratios. The photopatterns can be altered via AutoCAD-designed photomasks so that a variety of ductal and acinar mimetic structures can be mass-produced. In addition, by co-polymerizing methacrylated gelatin (methagel) with PEGDA, microstructures with increased cell adherence are synthesized. Biocompatibility and versatility of our approach is highlighted by culturing either SUM159 cells, which were seeded postfabrication, or MDA-MB-231 cells, which were encapsulated in hydrogels; cell viability is verified over 9 and 15 days, respectively. We believe that self-folding processes and associated tubular, curved, and folded constructs like the ones demonstrated here can facilitate the design of more accurate in vitro models for investigating ductal carcinoma.

  16. REVIEW: CHITOSAN BASED HYDROGEL POLYMERIC BEADS – AS DRUG DELIVERY SYSTEM

    Directory of Open Access Journals (Sweden)

    Manjusha Rani

    2010-11-01

    Full Text Available Chitosan obtained by alkaline deacetylation of chitin is a non-toxic, biocompatible, and biodegradable natural polymer. Chitosan-based hydrogel polymeric beads have been extensively studied as micro- or nano-particulate carriers in the pharmaceutical and medical fields, where they have shown promise for drug delivery as a result of their controlled and sustained release properties, as well as biocompatibility with tissue and cells. To introduce desired properties and enlarge the scope of the potential applications of chitosan, graft copolymerization with natural or synthetic polymers on it has been carried out, and also, various chitosan derivatives have been utilized to form beads. The desired kinetics, duration, and rate of drug release up to therapeutical level from polymeric beads are limited by specific conditions such as beads material and their composition, bead preparation method, amount of drug loading, drug solubility, and drug polymer interaction. The present review summarizes most of the available reports about compositional and structural effects of chitosan-based hydrogel polymeric beads on swelling, drug loading, and releasing properties. From the studies reviewed it is concluded that chitosan-based hydrogel polymeric beads are promising drug delivery systems.

  17. Kinetic investigation and lifetime prediction of Cs-NIPAM-MBA-based thermo-responsive hydrogels.

    Science.gov (United States)

    Othman, Muhammad Bisyrul Hafi; Khan, Abbas; Ahmad, Zulkifli; Zakaria, Muhammad Razlan; Ullah, Faheem; Akil, Hazizan Md

    2016-01-20

    This study attempted to clarify the influence of a cross-linker, N,N-methylenebisacrylamide (MBA), and N-isopropylacrylamide (NIPAM) on the non-isothermal kinetic degradation, solid state and lifetime of hydrogels using the Flynn-Wall-Ozawa (F-W-O), Kissinger, and Coats-Redfern (C-Red) methods. The series of dual-responsive Cs-PNIPAM-MBA microgels were synthesized by soapless-emulsion free radical copolymerization in an aqueous medium at 70 °C. The thermal properties were investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under nitrogen atmosphere. The apparent activation energy using the chosen Flynn-Wall-Ozawa and Kissinger methods showed that they fitted each other. Meanwhile, the type of solid state mechanism was determined using the Coats-Redfern method proposed for F1 (pure Cs) and F2 (Cs-PNIPAM-MBA hydrogel series) types, which comprise random nucleation with one nucleus reacting on individual particles, and random nucleation with two nuclei reacting on individual particles, respectively. On average, a higher Ea was attributed to the greater cross-linking density of the Cs hydrogel. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. The conjugation of nonsteroidal anti-inflammatory drugs (NSAID to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

    Directory of Open Access Journals (Sweden)

    Jiayang Li

    2013-05-01

    Full Text Available Here we report supramolecular hydrogelators made of nonsteroidal anti-inflammatory drugs (NSAID and small peptides. The covalent linkage of Phe–Phe and NSAIDs results in conjugates that self-assemble in water to form molecular nanofibers as the matrices of hydrogels. When the NSAID is naproxen (1, the resultant hydrogelator 1a forms a hydrogel at a critical concentration (cgc of 0.2 wt % at pH 7.0. Hydrogelator 1a, also acting as a general motif, enables enzymatic hydrogelation in which the precursor turns into a hydrogelator upon hydrolysis catalyzed by a phosphatase at physiological conditions. The conjugates of Phe–Phe with other NSAIDs, such as (R-flurbiprofen (2, racemic flurbiprofen (3, and racemic ibuprofen (4, are able to form molecular hydrogels, except in the case of aspirin (5. After the conjugation with the small peptides, NSAIDs exhibit improved selectivity to their targets. In addition, the peptides made of D-amino acids help preserve the activities of NSAIDs. Besides demonstrating that common NSAIDs are excellent candidates to promote aromatic–aromatic interaction in water to form hydrogels, this work contributes to the development of functional molecules that have dual or multiple roles and ultimately may lead to new molecular hydrogels of therapeutic agents for topical use.

  19. Carbon Nanotubes Reinforced Maleic Anhydride-Modified Xylan-g-Poly(N-isopropylacrylamide) Hydrogel with Multifunctional Properties

    Science.gov (United States)

    Liu, Xinxin; Song, Tao; Chang, Minmin; Meng, Ling; Wang, Xiaohui; Sun, Runcang; Ren, Junli

    2018-01-01

    Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified xylan grafted with poly(N-isopropylacrylamide) (MAX-g-PNIPAM) hydrogels network. It was found that the addition of AT-CNTs affected the MAX-g-PNIPAM hydrogel structure, the swelling ratio and mechanical properties, and imparted the hydrogel with new properties of electrical conductivity and near infrared region (NIR) photothermal conversion. AT-CNTs could reinforce the mechanical properties of MAX-g-PNIPAM hydrogels, being up to 83 kPa for the compressive strength when the amount was 11 wt %, which was eight times than that of PNIPAM hydrogel and four times than that of MAX-g-PNIPAM hydrogel. The electroconductibility was enhanced by the increase of AT-CNTs amounts. Meanwhile, the composite hydrogel also exhibited multiple shape memory and NIR photothermal conversion properties, and water temperature was increased from 26 °C to 56 °C within 8 min under the NIR irradiation. Thus, the AT-CNTs reinforced MAX-g-PNIPAM hydrogel possessed promising multifunctional properties, which offered many potential applications in the fields of biosensors, thermal-arrest technology, and drug-controlled release. PMID:29495611

  20. Synthesis and Characterization of 5-Fluorouracil-Loaded Glutaraldehyde Crosslinked Chitosan Hydrogels

    Directory of Open Access Journals (Sweden)

    Zehra ÖZBAŞ

    2016-11-01

    Full Text Available In this work, the characterization and drug release behavior of 5-fluorouracil-loaded glutaraldehyde-crosslinked chitosan hydrogels have been studied. The structure of the hydrogels were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction, also their properties were compared with those of the drug-unloaded hydrogels. The equilibrium swelling studies and drug release profiles were determined at 37°C in two different pHs (2.1 and 7.4. The results indicated that increased chitosan concentration in the hydrogel decreased the swelling and drug release values and the hydrogels released nearly the same amount of 5-fluorouracil in both acidic (~59% and basic medium (~50%.

  1. Development of an in situ polymeric hydrogel implant of ...

    African Journals Online (AJOL)

    Purpose: To prepare and characterize in situ gel-forming implants of methylprednisolone for the treatment of spinal cord injuries. Methods: In situ hydrogels of methylprednisolone were prepared by dispersing polylactide glycolic acid (PLGA) polymer and methylprednisolone in N-methyl-pyrrolidone solvent, and subsequent ...

  2. Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, N. Narayana, E-mail: nagireddynarayana@gmail.com [Center for Advanced Biomaterials for Healthcare, Istituto Italiano di Tecnologia@CRIB, Largo Barsanti e Matteucci 53, 80125 Napoli (Italy); Ravindra, S. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709 (South Africa); Reddy, N. Madhava [Department of Environmental Science, Gates Institute of Technology, NH-7, Gooty, Anantapuram, Andhra Pradesh (India); Rajinikanth, V. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709 (South Africa); Raju, K. Mohana [Synthetic Polymer Laboratory, Department of Polymer Science & Technology, S.K. University, Anantapuram, Andhra Pradesh (India); Vallabhapurapu, Vijaya Srinivasu [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709 (South Africa)

    2015-11-15

    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. - Highlights: • We have developed temperature responsive hydrogel magnetic nanocomposites. • Addition of AMPS monomer to this magnetic hydrogel enhances the temperature sensitivity to 40–43 °C. • Similarly the sulfonic groups present in the AMPS units enhances the swelling ratio of magnetic hydrogels. • AMPS acts as good stabilizing agent for nanoparticles in the magnetic nanogel.

  3. Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

    International Nuclear Information System (INIS)

    Reddy, N. Narayana; Ravindra, S.; Reddy, N. Madhava; Rajinikanth, V.; Raju, K. Mohana; Vallabhapurapu, Vijaya Srinivasu

    2015-01-01

    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. - Highlights: • We have developed temperature responsive hydrogel magnetic nanocomposites. • Addition of AMPS monomer to this magnetic hydrogel enhances the temperature sensitivity to 40–43 °C. • Similarly the sulfonic groups present in the AMPS units enhances the swelling ratio of magnetic hydrogels. • AMPS acts as good stabilizing agent for nanoparticles in the magnetic nanogel

  4. Hybrid dendrimer hydrogel/poly(lactic-co-glycolic acid) nanoparticle platform: an advanced vehicle for topical delivery of antiglaucoma drugs and a likely solution to improving compliance and adherence in glaucoma management.

    Science.gov (United States)

    Yang, Hu; Leffler, Christopher T

    2013-03-01

    Glaucoma therapy typically begins with topical medications, of which there are 4 major classes in common use in the United States: beta-adrenergic antagonists, alpha-agonists, carbonic anhydrase inhibitors, and prostaglandin analogs. Unfortunately, all 4 classes require at least daily dosing, and 3 of the 4 classes are approved to be administered 2 or 3 times daily. This need for frequent dosing with multiple medications makes compliance difficult. Longer-acting formulations and combinations that require less frequent administration might improve compliance and therefore medication effectiveness. Recently, we developed an ocular drug delivery system, a hybrid dendrimer hydrogel/poly(lactic-co-glycolic acid) nanoparticle platform for delivering glaucoma therapeutics topically. This platform is designed to deliver glaucoma drugs to the eye efficiently and release the drug in a slow fashion. Furthermore, this delivery platform is designed to be compatible with many of the glaucoma drugs that are currently approved for use. In this article, we review this new delivery system with in-depth discussion of its structural features, properties, and preclinical application in glaucoma treatment. In addition, future directions and translational efforts for marketing this technology are elaborated.

  5. Towards retrievable vascularized bioartificial pancreas: induction and long-lasting stability of polymeric mesh implant vascularized with the help of acidic and basic fibroblast growth factors and hydrogel coating.

    Science.gov (United States)

    Prokop, A; Kozlov, E; Nun Non, S; Dikov, M M; Sephel, G C; Whitsitt, J S; Davidson, J M

    2001-01-01

    We seek to improve existing methodologies for allogenic grafting of pancreatic islets. The lack of success of encapsulated transplanted islets inside the peritoneal cavity is presently attributed to poor vascularization of the implant. A thick, fibrotic capsule often surrounds the graft, limiting survival. We have tested the hypothesis that neovascularization of the graft material can be induced by the addition of proper angiogenic factors embedded within a polymeric coat. Biocompatible and nonresorbable meshes coated with hydrophilic polymers were implanted in rats and harvested after 1-, 6-, and 12-week intervals. The implant response was assessed by histological observations on the degree of vascularity, fibrosis, and inflammation. Macrostructural geometry of meshes was conducive to tissue ingrowth into the interstitial space between the mesh filaments. Hydrogel coating with incorporated acidic or basic FGF in an electrostatic complex with polyelectrolytes and/or with heparin provided a sustained slow release of the angiogenic growth factor. Anti-factor VIII and anti-collagen type IV antibodies and a GSL I-B4 lectin were used to measure the extent of vascularization. Vigorous and persistent vascularization radiated several hundred microns from the implant. The level of vascularization should provide a sufficient diffusion of nutrients and oxygen to implanted islets. Based on our observations, stable vascularization may require a sustained angiogenic signal to allow for the development of a permanent implant structure.

  6. Synthesis and characterization of cloisite-30B clay dispersed poly (acryl amide/sodium alginate)/AgNp hydrogel composites for the study of BSA protein drug delivery and antibacterial activity

    Science.gov (United States)

    Nanjunda Reddy, B. H.; Ranjan Rauta, Pradipta; Venkatalakshimi, V.; Sreenivasa, Swamy

    2018-02-01

    The aim of this research is to inspect the effect of Cloisite-30B (C30B) modified clay dispersed poly (acrylamide-co-Sodiumalginate)/AgNp hydrogel nanocomposites (PASA/C30B/Ag) for drug delivery and antibacterial activity. A novel hydrogel composite based sodium alginate (SA) and the inorganic modified clay with silver nano particle (C30B/AgNps)polymer hydrogel composites are synthesized via the graft copolymerization of acrylamide (AAm) in an aqueous medium with methylene bisacrylamide (MBA) as a crosslinking agent and ammonium per sulfate(APS) as an initiator. The UV/Visible spectroscopy of obtained composites is successfully studied, which confirms the occurrence of AgNps in the hydrogel composites. And the swelling capacity and bovine serum albumin (BSA) protein as model drug delivery study for these hydrogel nanocomposites have been carried out. The C30B/Ag filled hydrogel composites exhibit superior water absorbency or swelling capacity compared to pure samples and it is establish that the formulations with clay (C30B) dispersed silver nanocomposite hydrogels show improved and somewhat faster rate of drug delivery than other formulations(pure systems) and SEM and TEM reports suggests that the size of AgNps in the composite hydrogels is in the range of 5-10 nm with shrunken surface and the antibacterial characterizations for gram positive and gram negative bacteria are carried out by using Streptococcus faecalis (S. Faecalis) and Escherichia coli (E.coli) as model bacteria and the hydrogel composites of PASA/C30B/Ag shows exceptional antibacterial activity against both the bacteria as compared to pure hydrogel composites samples.

  7. The Radiation Induced Graft Copolymerization of Methacrylic Acid to Nylon; Copolymerisation par greffe de l'acide methacrylique sur le nylon, provoquee par irradiation; Obluchenie vyzyvaet graft-kopolimerizats yu metakrilovoj kisloty v nejlone; Injerto del acido metacrilico en el nylon por copolimerizacion radioinducida

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, R; Thomas, J K

    1960-07-15

    The grafting of methacrylic acid to nylon by the preirradiation technique has been studied. The rate of grafting is appreciably larger than that of homopolymerization. No simple relation exists between reaction rate and total dose. The temperature dependence of the rate of grafting to the fibre, preirradiated in air, indicates that initiation of grafting is likely to take place by decomposition of peroxide groups formed on irradiation. Electrical resistance measurements on the irradiated fibre indicate that this has been reduced by a factor of 10. (author) [French] On a etudie le greffage de l'acide methacrylique sur du nylon par la technique de preirradiation. La vitesse du greffage est sensiblement plus grande que celle de l'homopolymerisation. Il n'existe pas de rapport simple entre la vitesse de reaction et la dose totale. Le fait que la vitesse du greffage sur la fibre, pre-irradiee a l'air, depend de la temperature, indique que l'amorcage de la greffe est susceptible d'etre provoque par la decomposition des groupements de peroxyde formes lors de l'irradiation. Les mesures de resistance electrique effectuees sur la fibre irradiee indiquent que cette resistance a ete reduite au dixieme de la valeur originale. (author) [Spanish] Al estudiar la copolimerizacio n de injerto del acido metacrilico en el nylon por el procedimiento de preirradiacion, los autores comprobaron que la velocidad de injerto es sensiblemente mas elevada que la de homopolimerizacion. No existe una relacion sencilla entre la velocidad de reaccion y la dosis total. La influencia de la temperatura sobre la velocidad de injerto en la fibra previamente irradiada en aire indica que el proceso se inicia por descomposicion de los grupos peroxido formados durante la irradiacion. Las mediciones efectuadas demuestran que la resistencia electrica de la fibra irradiada solo alcanza la decima parte de la correspondiente a la fibra no tratada. (author) [Russian] Bylo provedeno izuchenie prosachivaniya

  8. The Formation Mechanism of Hydrogels.

    Science.gov (United States)

    Lu, Liyan; Yuan, Shiliang; Wang, Jing; Shen, Yun; Deng, Shuwen; Xie, Luyang; Yang, Qixiang

    2017-06-12

    Hydrogels are degradable polymeric networks, in which cross-links play a vital role in structure formation and degradation. Cross-linking is a stabilization process in polymer chemistry that leads to the multi-dimensional extension of polymeric chains, resulting in network structures. By cross-linking, hydrogels are formed into stable structures that differ from their raw materials. Generally, hydrogels can be prepared from either synthetic or natural polymers. Based on the types of cross-link junctions, hydrogels can be categorized into two groups: the chemically cross-linked and the physically cross-linked. Chemically cross-linked gels have permanent junctions, in which covalent bonds are present between different polymer chains, thus leading to excellent mechanical strength. Although chemical cross-linking is a highly resourceful method for the formation of hydrogels, the cross-linkers used in hydrogel preparation should be extracted from the hydrogels before use, due to their reported toxicity, while, in physically cross-linked gels, dissolution is prevented by physical interactions, such as ionic interactions, hydrogen bonds or hydrophobic interactions. Physically cross-linked methods for the preparation of hydrogels are the alternate solution for cross-linker toxicity. Both methods will be discussed in this essay. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. Hydrogel nanoparticles in drug delivery.

    Science.gov (United States)

    Hamidi, Mehrdad; Azadi, Amir; Rafiei, Pedram

    2008-12-14

    Hydrogel nanoparticles have gained considerable attention in recent years as one of the most promising nanoparticulate drug delivery systems owing to their unique potentials via combining the characteristics of a hydrogel system (e.g., hydrophilicity and extremely high water content) with a nanoparticle (e.g., very small size). Several polymeric hydrogel nanoparticulate systems have been prepared and characterized in recent years, based on both natural and synthetic polymers, each with its own advantages and drawbacks. Among the natural polymers, chitosan and alginate have been studied extensively for preparation of hydrogel nanoparticles and from synthetic group, hydrogel nanoparticles based on poly (vinyl alcohol), poly (ethylene oxide), poly (ethyleneimine), poly (vinyl pyrrolidone), and poly-N-isopropylacrylamide have been reported with different characteristics and features with respect to drug delivery. Regardless of the type of polymer used, the release mechanism of the loaded agent from hydrogel nanoparticles is complex, while resulting from three main vectors, i.e., drug diffusion, hydrogel matrix swelling, and chemical reactivity of the drug/matrix. Several crosslinking methods have been used in the way to form the hydrogel matix structures, which can be classified in two major groups of chemically- and physically-induced crosslinking.

  10. E-beam crosslinked, biocompatible functional hydrogels incorporating polyaniline nanoparticles

    International Nuclear Information System (INIS)

    Dispenza, C.; Sabatino, M.-A.; Niconov, A.; Chmielewska, D.; Spadaro, G.

    2012-01-01

    PANI aqueous nanocolloids in their acid-doped, inherently conductive form were synthesised by means of suitable water soluble polymers used as stabilisers. In particular, poly(vinyl alcohol) (PVA) or chitosan (CT) was used to stabilise PANI nanoparticles, thus preventing PANI precipitation during synthesis and upon storage. Subsequently, e-beam irradiation of the PANI dispersions has been performed with a 12 MeV Linac accelerator. PVA-PANI nanocolloid has been transformed into a PVA-PANI hydrogel nanocomposite by radiation induced crosslinking of PVA. CT-PANI nanoparticles dispersion, in turn, was added to PVA to obtain wall-to-wall gels, as chitosan mainly undergoes chain scission under the chosen irradiation conditions. While the obtainment of uniform PANI particle size distribution was preliminarily ascertained with laser light scattering and TEM microscopy, the typical porous structure of PVA-based freeze dried hydrogels was observed with SEM microscopy for the hydrogel nanocomposites. UV−visible absorption spectroscopy demonstrates that the characteristic, pH-dependent and reversible optical absorption properties of PANI are conferred to the otherwise optically transparent PVA hydrogels. Selected formulations have been also subjected to MTT assays to prove the absence of cytotoxicity. - Highlights: ► PANI nanocolloids were chemically synthesised in the presence of PVA and chitosan. ► PANI dispersions were transformed into hydrogel nanocomposites by e-beam irradiation. ► Characteristic optical properties of PANI were shown by the nanocomposite hydrogels. ► Absence of cytotoxicity for the nanocomposite hydrogels is demonstrated. ► Results encourage developments for application in biosensing and smart drug delivery.

  11. Stimuli-sensitive hydrogels: A novel ophthalmic drug delivery system

    Directory of Open Access Journals (Sweden)

    Singh Vinod

    2010-01-01

    Full Text Available Background: Stimuli-sensitive hydrogels are three-dimensional, hydrophilic, polymeric networks capable of imbibing large amounts of water or biological fluids on stimulation, such as pH, temperature and ionic change. Aim: To develop hydrogels that are sensitive to stimuli, i.e. pH, in the cul-de-sac of the eye for providing a prolonged effect and increased bioavailability with reduction in frequency of administration. Materials and Methods: Hydrogels were formulated by using timolol maleate as the model drug, polyacrylic acid as the gelling agents, hydroxyl ethyl cellulose as the viscolizer and sodium chloride as the isotonic agent. Stirring of ingredients in pH 4 phosphate buffer at high speed was carried out. The dynamic dialysis technique was used for drug release studies. In vivo study for reduction in intraocular pressure was carried out by using albino rabbits. Statistical Analysis: Drug release studies data were used for statistical analysis in first-order plots, Higuchi plots and Peppas exponential plots. Student t-test was performed for in vivo study. Results: Viscosity of the hydrogel increases from 3.84 cps to 9.54 cps due to change in pH 4 to pH 7.4. The slope value of the Peppas equation was found to be 0.3081, 0.3743 and 0.2964. Up to 80% of drug was released in an 8 h drug release study. Sterile hydrogels with no ocular irritation were obtained. Conclusions: Hydrogels show increase in viscosity due to change in pH. Hydrogels were therapeutically effacious, stable, non-irritant and showed Fickian diffusion. In vivo results clearly show a prolonged reduction in intraocular pressure, which was helpful for reduction in the frequency of administration.

  12. Use of additives to fine-tune the composition of carbonate units in the polymer formed by copolymerization of co2 with epoxide: application to the synthesis of polycarbonate-based block copolymers and of telechelics

    KAUST Repository

    Feng, Xiaoshuang

    2016-12-22

    Embodiments of the present disclosure describe a method of making a polycarbonate, comprising contacting one or more cyclic monomers and carbon dioxide in the presence of one or more of a Lewis acid catalyst, an initiator, and an ionic liquid; and agitating, sufficient to copolymerize the one or more cyclic monomers and carbon dioxide to create a polycarbonate. Embodiments of the present disclosure further describe a method of controlling a polymer composition, comprising contacting one or more cyclic monomers and carbon dioxide; adjusting an amount of one or more of a Lewis acid catalyst, an ionic liquid, and an initiator in the presence of the one or more cyclic monomers and carbon dioxide, sufficient to selectively modify a resulting polycarbonate; and agitating, sufficient to copolymerize the one or more cyclic monomers and carbon dioxide to create the polycarbonate.

  13. Use of additives to fine-tune the composition of carbonate units in the polymer formed by copolymerization of co2 with epoxide: application to the synthesis of polycarbonate-based block copolymers and of telechelics

    KAUST Repository

    Feng, Xiaoshuang; Zhang, Dongyue; Gnanou, Yves; Hadjichristidis, Nikolaos

    2016-01-01

    Embodiments of the present disclosure describe a method of making a polycarbonate, comprising contacting one or more cyclic monomers and carbon dioxide in the presence of one or more of a Lewis acid catalyst, an initiator, and an ionic liquid; and agitating, sufficient to copolymerize the one or more cyclic monomers and carbon dioxide to create a polycarbonate. Embodiments of the present disclosure further describe a method of controlling a polymer composition, comprising contacting one or more cyclic monomers and carbon dioxide; adjusting an amount of one or more of a Lewis acid catalyst, an ionic liquid, and an initiator in the presence of the one or more cyclic monomers and carbon dioxide, sufficient to selectively modify a resulting polycarbonate; and agitating, sufficient to copolymerize the one or more cyclic monomers and carbon dioxide to create the polycarbonate.

  14. A composite hydrogels-based photonic crystal multi-sensor

    International Nuclear Information System (INIS)

    Chen, Cheng; Zhu, Zhigang; Zhu, Xiangrong; Yu, Wei; Liu, Mingju; Ge, Qiaoqiao; Shih, Wei-Heng

    2015-01-01

    A facile route to prepare stimuli-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) gelated crystalline colloidal array photonic crystal material was developed. PVA was physically gelated by utilizing an ethanol-assisted method, the resulting hydrogel/crystal composite film was then functionalized with PAA to form an interpenetrating hydrogel film. This sensor film is able to efficiently diffract the visible light and rapidly respond to various environmental stimuli such as solvent, pH and strain, and the accompanying structural color shift can be repeatedly changed and easily distinguished by naked eye. (paper)

  15. Semi-Interpenetrating polymer network hydrogels based on aspen hemicellulose and chitosan: Effect of crosslinking sequence on hydrogel properties

    Science.gov (United States)

    Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

    2012-01-01

    Semi-interpenetrating network hydrogel films were prepared using hemicellulose and chemically crosslinked chitosan. Hemicellulose was extracted from aspen by using a novel alkaline treatment and characterized by HPSEC, and consisted of a mixture of high and low molecular weight polymeric fractions. HPLC analysis of the acid hydrolysate of the hemicellulose showed that...

  16. Autonomously Self-Adhesive Hydrogels as Building Blocks for Additive Manufacturing.

    Science.gov (United States)

    Deng, Xudong; Attalla, Rana; Sadowski, Lukas P; Chen, Mengsu; Majcher, Michael J; Urosev, Ivan; Yin, Da-Chuan; Selvaganapathy, P Ravi; Filipe, Carlos D M; Hoare, Todd

    2018-01-08

    We report a simple method of preparing autonomous and rapid self-adhesive hydrogels and their use as building blocks for additive manufacturing of functional tissue scaffolds. Dynamic cross-linking between 2-aminophenylboronic acid-functionalized hyaluronic acid and poly(vinyl alcohol) yields hydrogels that recover their mechanical integrity within 1 min after cutting or shear under both neutral and acidic pH conditions. Incorporation of this hydrogel in an interpenetrating calcium-alginate network results in an interfacially stiffer but still rapidly self-adhesive hydrogel that can be assembled into hollow perfusion channels by simple contact additive manufacturing within minutes. Such channels withstand fluid perfusion while retaining their dimensions and support endothelial cell growth and proliferation, providing a simple and modular route to produce customized cell scaffolds.

  17. Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Development of visible-light responsive and mechanically enhanced "smart" UCST interpenetrating network hydrogels.

    Science.gov (United States)

    Xu, Yifei; Ghag, Onkar; Reimann, Morgan; Sitterle, Philip; Chatterjee, Prithwish; Nofen, Elizabeth; Yu, Hongyu; Jiang, Hanqing; Dai, Lenore L

    2017-12-20

    An interpenetrating polymer network (IPN), chlorophyllin-incorporated environmentally responsive hydrogel was synthesized and exhibited the following features: enhanced mechanical properties, upper critical solution temperature (UCST) swelling behavior, and promising visible-light responsiveness. Poor mechanical properties are known challenges for hydrogel-based materials. By forming an interpenetrating network between polyacrylamide (PAAm) and poly(acrylic acid) (PAAc) polymer networks, the mechanical properties of the synthesized IPN hydrogels were significantly improved compared to hydrogels made of a single network of each polymer. The formation of the interpenetrating network was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), the analysis of glass transition temperature, and a unique UCST responsive swelling behavior, which is in contrast to the more prevalent lower critical solution temperature (LCST) behaviour of environmentally responsive hydrogels. The visible-light responsiveness of the synthesized hydrogel also demonstrated a positive swelling behavior, and the effect of incorporating chlorophyllin as the chromophore unit was observed to reduce the average pore size and further enhance the mechanical properties of the hydrogel. This interpenetrating network system shows potential to serve as a new route in developing "smart" hydrogels using visible-light as a simple, inexpensive, and remotely controllable stimulus.

  19. Synthesis of Collagen-Based Hydrogel Nanocomposites Using Montmorillonite and Study of Adsorption Behavior of Cd from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Gholam Bagheri Marandi

    2013-04-01

    Full Text Available Novel collagen-based hydrogel nanocomposites were synthesized by graft copolymerization of acrylamide and maleic anhydrid in the presence of different amounts of montmorillonite, using methylenebisacrylamide (MBAand ammonium persulfate (APS as crosslinker and initiator, respectively. The optimum amount of clay on the swelling properties of the samples was studied. It was found that the hydrogel nanocomposites exhibited improved swelling capacity compared with the clay-free hydrogel. Gel content was also studied and the resultsindicated that the inclusion of montmorillonite causes an increase in gel content. The sorption behavior of heavy metal ion from aqueous solutions was investigated by its relationship with pH, contact time, initial concentration of metal ion and also, montmorillonite content of the nanocomposites. The experimental data showed thatCd2+ ion adsorption increases with increasing initial concentration of Cd2+ ion in solution and the clay content. Also, the results indicated that more than 88% of the maximum adsorption capacities toward Cd2+ ion were achieved within the initial 10 minute. Functional groups of the prepared hydrogels have shown complexation abilitywith metal ions and improving hydrogels' adsorption properties. It was concluded that the nanocomposites could be used as fast-responsive, and high capacity sorbent materials in Cd2+ ion removing processes. The prepared hydrogel nanocomposites were characerized by means of XRD patterns, TGA thermal methods and FTIRspectroscopy. The XRD patterns of nanocomposites showed that the interlayer distance of montmorillonite was changed and the clay sheets were exfoliated. Furthermore, the results showed that by increasing the montmorillonite content, thermal stability of the nanocomposites was clearly improved.

  20. Desmosine-Inspired Cross-Linkers for Hyaluronan Hydrogels

    Science.gov (United States)

    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.

  1. Biocompatible Amphiphilic Hydrogel-Solid Dimer Particles as Colloidal Surfactants.

    Science.gov (United States)

    Chen, Dong; Amstad, Esther; Zhao, Chun-Xia; Cai, Liheng; Fan, Jing; Chen, Qiushui; Hai, Mingtan; Koehler, Stephan; Zhang, Huidan; Liang, Fuxin; Yang, Zhenzhong; Weitz, David A

    2017-12-26

    Emulsions of two immiscible liquids can slowly coalesce over time when stabilized by surfactant molecules. Pickering emulsions stabilized by colloidal particles can be much more stable. Here, we fabricate biocompatible amphiphilic dimer particles using a hydrogel, a strongly hydrophilic material, and achieve large contrast in the wetting properties of the two bulbs, resulting in enhanced stabilization of emulsions. We generate monodisperse single emulsions of alginate and shellac solution in oil using a flow-focusing microfluidics device. Shellac precipitates from water and forms a solid bulb at the periphery of the droplet when the emulsion is exposed to acid. Molecular interactions result in amphiphilic dimer particles that consist of two joined bulbs: one hydrogel bulb of alginate in water and the other hydrophobic bulb of shellac. Alginate in the hydrogel compartment can be cross-linked using calcium cations to obtain stable particles. Analogous to surfactant molecules at the interface, the resultant amphiphilic particles stand at the water/oil interface with the hydrogel bulb submerged in water and the hydrophobic bulb in oil and are thus able to stabilize both water-in-oil and oil-in-water emulsions, making these amphiphilic hydrogel-solid particles ideal colloidal surfactants for various applications.

  2. Improved stability and enhanced efficiency to degrade chlorimuron-ethyl by the entrapment of esterase SulE in cross-linked poly (γ-glutamic acid)/gelatin hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liqiang [State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang (China); University of Chinese Academy of Sciences, Beijing (China); Li, Xinyu; Li, Xu; Su, Zhencheng; Zhang, Chenggang; Xu, MingKai [State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang (China); Zhang, Huiwen, E-mail: hwzhang@iae.ac.cn [State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang (China)

    2015-04-28

    Highlights: • Esterase SulE was entrapped in a three-dimensional network of CPE. • CPE-SulE obviously improved thermostability, pH stability and reusability. • CPE-SulE displayed obviously enhanced efficiency in degrading chlorimuron-ethyl. • The three-dimensional network and kinetic parameters of CPE-SulE were analysed. • CPE-SulE possesses the great potential to remediate chlorimuron-ethyl contaminated in situ. - Abstract: Free enzymes often undergo some problems such as easy deactivation, low stability, and less recycling in biodegradation processes, especially in soil condition. A novel esterase SulE, which is responsible for primary degradation of a wide range of sulfonylurea herbicides by methyl or ethyl ester de-esterification, was expressed by strain Hansschlegelia sp. CHL1 and entrapped for the first time in an environment-friendly, biocompatible and biodegradable cross-linked poly (γ-glutamic acid)/gelatin hydrogel (CPE). The activity and stability of CPE-SulE were compared with free SulE under varying pH and temperature condition by measuring chlorimuron-ethyl residue. Meanwhile, the three-dimensional network of CPE-SulE was verified by scanning electron microscopy (SEM). The results showed that CPE-SulE obviously improved thermostability, pH stability and reusability compared with free SulE. Furthermore, CPE-SulE enhanced degrading efficiency of chlorimuron-ethyl in both soil and water system, especially in acid environment. The characteristics of CPE-SulE suggested the great potential to remediate chlorimuron-ethyl contaminated soils in situ.

  3. Improved stability and enhanced efficiency to degrade chlorimuron-ethyl by the entrapment of esterase SulE in cross-linked poly (γ-glutamic acid)/gelatin hydrogel

    International Nuclear Information System (INIS)

    Yang, Liqiang; Li, Xinyu; Li, Xu; Su, Zhencheng; Zhang, Chenggang; Xu, MingKai; Zhang, Huiwen

    2015-01-01

    Highlights: • Esterase SulE was entrapped in a three-dimensional network of CPE. • CPE-SulE obviously improved thermostability, pH stability and reusability. • CPE-SulE displayed obviously enhanced efficiency in degrading chlorimuron-ethyl. • The three-dimensional network and kinetic parameters of CPE-SulE were analysed. • CPE-SulE possesses the great potential to remediate chlorimuron-ethyl contaminated in situ. - Abstract: Free enzymes often undergo some problems such as easy deactivation, low stability, and less recycling in biodegradation processes, especially in soil condition. A novel esterase SulE, which is responsible for primary degradation of a wide range of sulfonylurea herbicides by methyl or ethyl ester de-esterification, was expressed by strain Hansschlegelia sp. CHL1 and entrapped for the first time in an environment-friendly, biocompatible and biodegradable cross-linked poly (γ-glutamic acid)/gelatin hydrogel (CPE). The activity and stability of CPE-SulE were compared with free SulE under varying pH and temperature condition by measuring chlorimuron-ethyl residue. Meanwhile, the three-dimensional network of CPE-SulE was verified by scanning electron microscopy (SEM). The results showed that CPE-SulE obviously improved thermostability, pH stability and reusability compared with free SulE. Furthermore, CPE-SulE enhanced degrading efficiency of chlorimuron-ethyl in both soil and water system, especially in acid environment. The characteristics of CPE-SulE suggested the great potential to remediate chlorimuron-ethyl contaminated soils in situ

  4. In situ NMR and modeling studies of nitroxide mediated copolymerization of styrene and n-butyl acrylate

    NARCIS (Netherlands)

    Hlalele, L.; Klumperman, L.

    2011-01-01

    The combination of in situ1H NMR and in situ31P NMR was used to study the nitroxide mediated copolymerization of styrene and n-butyl acrylate. The alkoxyamine MAMA-DEPN was employed to initiate and mediate the copolymerization. The nature of the ultimate/terminal monomer units of dormant polymer

  5. Spectroscopic study of monitoring the kinetics of radical copolymerization of di(ethylene glycol) bis(allylcarbonate) and 2-naphthylmethacrylate

    Science.gov (United States)

    Barashkov, N. N.; Novikova, T. S.; Sakhno, T. V.; Bulgakova, L. M.

    1996-03-01

    The results of fluorescence monitoring in the radical copolymerization of di(ethylene glycol) bis(allylcarbonate) and 2-naphthylmethacrylate are discussed. Our studies suggest that data based on measurement of the intensity of the fluorescence band at 345 nm during copolymerization are in good agreement with the data obtained by the traditional dilatometric method.

  6. HYDROGELS AND THEIR APLICATION AREAS

    Directory of Open Access Journals (Sweden)

    AÇIKEL Safiye Meriç

    2016-05-01

    Full Text Available Hydrogels, being polymeric material,are named “Hydrophilic Polymer” because of their capable of holding large amounts of water in their three-dimensional networks. Hydrogels is not solved in water; however they have been swollen to their balace volume. Because of this swell behavior, they can adsorb big quantity of water in this structure. So they can term of “three sized polymers” due to protect their existing shape. Their cross linked bound structures are able to covalent or ionic and also one polymer which can for use of hydrogel polymer, must have hydrophilic groups such as carboxyl, carbonyl, amine and amide in main chains or side chains, and because of these groups water bound the polymer and polymer start to swell with rising volume and mass. Swell behavior of hydrogel is interested in quantity of hydrophilic groups. Hydrogels can use in different industrial and environmental areas with this high amount water holding capacity. They are used in food industry, biomedical, bioengineering, biotechnology, veterinary, pharmacist, agriculture, telecommunication, etc. Especially in current life, baby nappy has been including inside hydrogel beads. Also they used in contact lens, artificial cornea, synthetic cartilage and gullet, controlled medicine release, surgery yarns. This article general inform about usage area of hydrogels.

  7. Quantitative determination of insulin entrapment efficiency in triblock copolymeric nanoparticles by high-performance liquid chromatography.

    Science.gov (United States)

    Xu, Xiongliang; Fu, Yao; Hu, Haiyan; Duan, Yourong; Zhang, Zhirong

    2006-04-11

    A rapid and effective isocratic chromatographic procedure was described in this paper for the determination of insulin entrapment efficiency (EE) in triblock copolymeric nanoparticles using reversed-phase high-performance liquid chromatography (RP-HPLC) with an ultraviolet/visible detector at low flow rate. The method has been developed on a Shimadzu Shim-pack VP-ODS column (150 mm x 4.6 mm, 5 microm, Chiyoda-Ku, Tokyo, Japan) using a mixture of 0.2 M sodium sulfate anhydrous solution adjusted to pH 2.3 with phosphoric acid and acetonitrile (73:27, v/v) as mobile phase at the flow rate of 0.8 ml min(-1) and a 214 nm detection. The method was validated in terms of selectivity, linearity, precision, accuracy, solution stability, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve was linear in the concentration range of 2.0-500.0 microg ml(-1), and the limits of detection and quantitation were 8 and 20 ng, respectively. The mean recovery of insulin from spiked samples, in a concentration range of 8-100 microg ml(-1), was 98.96% (R.S.D.= 2.51%, n = 9). The intra- and inter-assay coefficients of variation were less than 2.24%. The proposed method has the advantages of simple pretreatment, rapid isolation, high specificity and precision, which can be used for direct analysis of insulin in commercially available raw materials, formulations of nanoparticles, and drug release as well as stability studies.

  8. Graphene oxide and hyperbranched polymer-toughened hydrogels with improved absorption properties and durability

    DEFF Research Database (Denmark)

    Yu, Yang; De Andrade, Leandro Carvalho Xavier; Fang, Liming

    2015-01-01

    Hyperbranched polymers or/and graphene oxide nanosheets were used to synthesize poly(acrylic acid)-based hybrid hydrogels with high water absorption ability, excellent mechanical properties, and environmental remediation abilities through a novel one-step, cost-effective, and environmentally...... friendly method. The combination of hyperbranched polymers and graphene oxide nanosheets had synergistic effects on the final hybrid hydrogel, especially on the mechanical behaviors of the hydrogels, with Young's modulus, tensile strength at break and elongation at break increasing by 69, 308, and 848...

  9. Molecular and macro-scale analysis of enzyme-crosslinked silk hydrogels for rational biomaterial design.

    Science.gov (United States)

    McGill, Meghan; Coburn, Jeannine M; Partlow, Benjamin P; Mu, Xuan; Kaplan, David L

    2017-11-01

    Silk fibroin-based hydrogels have exciting applications in tissue engineering and therapeutic molecule delivery; however, their utility is dependent on their diffusive properties. The present study describes a molecular and macro-scale investigation of enzymatically-crosslinked silk fibroin hydrogels, and demonstrates that these systems have tunable crosslink density and diffusivity. We developed a liquid chromatography tandem mass spectroscopy (LC-MS/MS) method to assess the quantity and order of covalent tyrosine crosslinks in the hydrogels. This analysis revealed between 28 and 56% conversion of tyrosine to dityrosine, which was dependent on the silk concentration and reactant concentration. The crosslink density was then correlated with storage modulus, revealing that both crosslinking and protein concentration influenced the mechanical properties of the hydrogels. The diffusive properties of the bulk material were studied by fluorescence recovery after photobleaching (FRAP), which revealed a non-linear relationship between silk concentration and diffusivity. As a result of this work, a model for synthesizing hydrogels with known crosslink densities and diffusive properties has been established, enabling the rational design of silk hydrogels for biomedical applications. Hydrogels from naturally-derived silk polymers offer versitile opportunities in the biomedical field, however, their design has largely been an empirical process. We present a fundamental study of the crosslink density, storage modulus, and diffusion behavior of enzymatically-crosslinked silk hydrogels to better inform scaffold design. These studies revealed unexpected non-linear trends in the crosslink density and diffusivity of silk hydrogels with respect to protein concentration and crosslink reagent concentration. This work demonstrates the tunable diffusivity and crosslinking in silk fibroin hydrogels, and enables the rational design of biomaterials. Further, the characterization methods

  10. Mechano-responsive hydrogels crosslinked by reactive block copolymer micelles

    Science.gov (United States)

    Xiao, Longxi

    Hydrogels are crosslinked polymeric networks that can swell in water without dissolution. Owing to their structural similarity to the native extracelluar matrices, hydrogels have been widely used in biomedical applications. Synthetic hydrogels have been designed to respond to various stimuli, but mechanical signals have not incorporated into hydrogel matrices. Because most tissues in the body are subjected to various types of mechanical forces, and cells within these tissues have sophisticated mechano-transduction machinery, this thesis is focused on developing hydrogel materials with built-in mechano-sensing mechanisms for use as tissue engineering scaffolds or drug release devices. Self-assembled block copolymer micelles (BCMs) with reactive handles were employed as the nanoscopic crosslinkers for the construction of covalently crosslinked networks. BCMs were assembled from amphiphilic diblock copolymers of poly(n-butyl acrylate) and poly(acrylic acid) partially modified with acrylate. Radical polymerization of acrylamide in the presence of micellar crosslinkers gave rise to elastomeric hydrogels whose mechanical properties can be tuned by varying the BCM composition and concentration. TEM imaging revealed that the covalently integrated BCMs underwent strain-dependent reversible deformation. A model hydrophobic drug, pyrene, loaded into the core of BCMs prior to the hydrogel formation, was dynamically released in response to externally applied mechanical forces, through force-induced reversible micelle deformation and the penetration of water molecules into the micelle core. The mechano-responsive hydrogel has been studied for tissue repair and regeneration purposes. Glycidyl methacrylate (GMA)-modified hyaluronic acid (HA) was photochemically crosslinked in the presence of dexamethasone (DEX)-loaded crosslinkable BCMs. The resultant HA gels (HAxBCM) contain covalently integrated micellar compartments with DEX being sequestered in the hydrophobic core. Compared

  11. Dual Cross-Linked Biofunctional and Self-Healing Networks to Generate User-Defined Modular Gradient Hydrogel Constructs.

    Science.gov (United States)

    Wei, Zhao; Lewis, Daniel M; Xu, Yu; Gerecht, Sharon

    2017-08-01

    Gradient hydrogels have been developed to mimic the spatiotemporal differences of multiple gradient cues in tissues. Current approaches used to generate such hydrogels are restricted to a single gradient shape and distribution. Here, a hydrogel is designed that includes two chemical cross-linking networks, biofunctional, and self-healing networks, enabling the customizable formation of modular gradient hydrogel construct with various gradient distributions and flexible shapes. The biofunctional networks are formed via Michael addition between the acrylates of oxidized acrylated hyaluronic acid (OAHA) and the dithiol of matrix metalloproteinase (MMP)-sensitive cross-linker and RGD peptides. The self-healing networks are formed via dynamic Schiff base reaction between N-carboxyethyl chitosan (CEC) and OAHA, which drives the modular gradient units to self-heal into an integral modular gradient hydrogel. The CEC-OAHA-MMP hydrogel exhibits excellent flowability at 37 °C under shear stress, enabling its injection to generate gradient distributions and shapes. Furthermore, encapsulated sarcoma cells respond to the gradient cues of RGD peptides and MMP-sensitive cross-linkers in the hydrogel. With these superior properties, the dual cross-linked CEC-OAHA-MMP hydrogel holds significant potential for generating customizable gradient hydrogel constructs, to study and guide cellular responses to their microenvironment such as in tumor mimicking, tissue engineering, and stem cell differentiation and morphogenesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Polylactic acid vs. polyacrylamide hydrogel for treatment of facial lipoatrophy: a randomized controlled trial [Agence Nationale de Recherches sur le SIDA et les Hépatites Virales (ANRS) 132 SMILE].

    Science.gov (United States)

    Lafaurie, M; Dolivo, M; Girard, P-M; May, T; Bouchaud, O; Carbonnel, E; Madelaine, I; Loze, B; Porcher, R; Molina, J-M

    2013-08-01

    The aim of the study was to demonstrate the noninferiority of polyacrylamide hydrogel (PH) vs. polylactic acid (PLA) for the treatment of facial lipoatrophy in HIV-infected adults. A randomized, blinded, multicentre, noninferiority 96-week study was carried out. Patients with facial lipoatrophy were randomly assigned to receive intradermal injections with PH or PLA, and were blinded to the filler. The primary efficacy endpoint was patient satisfaction at week 48 assessed using a visual analogue scale score (VAS). Secondary efficacy end-points included cheek thickness and skin-fold, lipoatrophy grading and quality of life. Safety was assessed by the reporting of adverse events. A total of 148 patients were included in the study; 93% were men, the median age was 47 years, the median CD4 count was 528 cells/μL, and the median duration of antiretroviral therapy was 12 years. Mean VAS increased from 2.8 at baseline to 7.1 and 7.5 in the PLA and PH arms, respectively, at week 48 (P=0.0002 for noninferiority) and was sustained at week 96 (6.7 and 7.9 in the PLA and PH arms, respectively; P=0.003 for noninferiority). Cheek thickness and skin-fold increases and lipoatrophy improvement were similar in the two arms. Quality of life remained unchanged or improved depending on the questionnaire used. In injected patients, subcutaneous nodules emerged in 28 (41%) and 26 (37%) patients in the PLA and PH arms, respectively (P=0.73). Four patients in the PH arm developed severe inflammatory nodules, a median of 17 months after the last injection. PH and PLA have similar efficacies in the treatment of facial lipoatrophy, but PH may be associated with more delayed inflammatory nodules. © 2013 British HIV Association.

  13. Superabsorbent hydrogels via graft polymerization of acrylic acid from chitosan-cellulose hybrid and their potential in controlled release of soil nutrients.

    Science.gov (United States)

    Essawy, Hisham A; Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F

    2016-08-01

    Superabsorbent polymers fabricated via grafting polymerization of acrylic acid from chitosan (CTS) yields materials that suffer from poor mechanical strength. Hybridization of chitosan with cellulose (Cell) via chemical bonding using thiourea formaldehyde resin increases the flexibility of the produced hybrid (CTS/Cell). The hybridization process and post graft polymerization of acrylic acid was followed using Fourier transform infrared (FTIR). Also, the obtained structures were homogeneous and exhibited uniform surface as could be shown from imaging with scanning electron microscopy (SEM). Thus, the polymers derived from the grafting of polyacrylic acid from (CTS/Cell) gave rise to much more mechanically robust structures ((CTS/Cell)-g-PAA) that bear wide range of pH response due to presence of chitosan and polyacrylic acid in one homogeneous entity. Additionally, the obtained structures possessed greater water absorbency 390, 39.5g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced retention potential even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high grafting efficiency (GE%), 86.4%, and grafting yield (GY%), 750%. The new superabsorbent polymers proved to be very efficient devices for controlled release of fertilizers into the soil which expands their use in agriculture and horticultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Preparation of high water-swelling agricultural starch hydrogels by 60Co γ-radiation grafting

    International Nuclear Information System (INIS)

    Wang Qingjun; Quan Yiwu; Chen Qingmin

    2003-01-01

    The starch grafted acrylic acid was used to synthesize water-swelling hydrogels by 60 Co γ-radiation grafting technique. With radiation dose of about 7 kGy, the crosslinking reagent amount of 0.001%-0.1%, the pH value 5-8 and the starch amount of 10%-30%, we can produce 600 times water-swelling hydrogels which are of high performance, low cost and suitable for agriculture

  15. Chitosan–Cellulose Multifunctional Hydrogel Beads: Design, Characterization and Evaluation of Cytocompatibility with Breast Adenocarcinoma and Osteoblast Cells

    Science.gov (United States)

    Trivedi, Poonam; Saloranta-Simell, Tiina; Gradišnik, Lidija; Prabhakar, Neeraj; Smått, Jan-Henrik; Mohan, Tamilselvan; Gericke, Martin; Heinze, Thomas

    2018-01-01

    Cytocompatible polysaccharide-based functional scaffolds are potential extracellular matrix candidates for soft and hard tissue engineering. This paper describes a facile approach to design cytocompatible, non-toxic, and multifunctional chitosan-cellulose based hydrogel beads utilising polysaccharide dissolution in sodium hydroxide-urea-water solvent system and coagulation under three different acidic conditions, namely 2 M acetic acid, 2 M hydrochloric acid, and 2 M sulfuric acid. The effect of coagulating medium on the final chemical composition of the hydrogel beads is investigated by spectroscopic techniques (ATR–FTIR, Raman, NMR), and elemental analysis. The beads coagulated in 2 M acetic acid displayed an unchanged chitosan composition with free amino groups, while the beads coagulated in 2 M hydrochloric and sulfuric acid showed protonation of amino groups and ionic interaction with the counterions. The ultrastructural morphological study of lyophilized beads showed that increased chitosan content enhanced the porosity of the hydrogel beads. Furthermore, cytocompatibility evaluation of the hydrogel beads with human breast adenocarcinoma cells (soft tissue) showed that the beads coagulated in 2 M acetic acid are the most suitable for this type of cells in comparison to other coagulating systems. The acetic acid fabricated hydrogel beads also support osteoblast growth and adhesion over 192 h. Thus, in future, these hydrogel beads can be tested in the in vitro studies related to breast cancer and for bone regeneration. PMID:29315214

  16. Chitosan-Cellulose Multifunctional Hydrogel Beads: Design, Characterization and Evaluation of Cytocompatibility with Breast Adenocarcinoma and Osteoblast Cells.

    Science.gov (United States)

    Trivedi, Poonam; Saloranta-Simell, Tiina; Maver, Uroš; Gradišnik, Lidija; Prabhakar, Neeraj; Smått, Jan-Henrik; Mohan, Tamilselvan; Gericke, Martin; Heinze, Thomas; Fardim, Pedro

    2018-01-09

    Cytocompatible polysaccharide-based functional scaffolds are potential extracellular matrix candidates for soft and hard tissue engineering. This paper describes a facile approach to design cytocompatible, non-toxic, and multifunctional chitosan-cellulose based hydrogel beads utilising polysaccharide dissolution in sodium hydroxide-urea-water solvent system and coagulation under three different acidic conditions, namely 2 M acetic acid, 2 M hydrochloric acid, and 2 M sulfuric acid. The effect of coagulating medium on the final chemical composition of the hydrogel beads is investigated by spectroscopic techniques (ATR-FTIR, Raman, NMR), and elemental analysis. The beads coagulated in 2 M acetic acid displayed an unchanged chitosan composition with free amino groups, while the beads coagulated in 2 M hydrochloric and sulfuric acid showed protonation of amino groups and ionic interaction with the counterions. The ultrastructural morphological study of lyophilized beads showed that increased chitosan content enhanced the porosity of the hydrogel beads. Furthermore, cytocompatibility evaluation of the hydrogel beads with human breast adenocarcinoma cells (soft tissue) showed that the beads coagulated in 2 M acetic acid are the most suitable for this type of cells in comparison to other coagulating systems. The acetic acid fabricated hydrogel beads also support osteoblast growth and adhesion over 192 h. Thus, in future, these hydrogel beads can be tested in the in vitro studies related to breast cancer and for bone regeneration.

  17. Healing wounds - radiation processing technology for hydrogel dressing

    International Nuclear Information System (INIS)

    Varshney, Lalit

    2009-01-01

    Uses of hydrogels are known and have several applications in medical field. Drug delivery devices, contact lenses, wound dressing, artificial cartilage's or membranes, vascular prosthesis, gel coated catheters etc., are some of the examples. Due to direct relevance to human health, scientists have been continuously exploring these systems. Generally, hydro (water) gels contain 30-90% of water entrapped in a three dimensional network structure of a hydrophilic polymer. The large water content makes them highly bio-compatible and therefore preferred for use as biomaterials. Some of the hydrophilic polymers used in these applications include poly (vinyl pyrrolidone), poly (ethylene oxide), poly (vinyl alcohol) and poly (acrylic acid ). Depending upon the nature of application, the size of these hydrogel can vary from nanometers (nanogels, injectable hydrogels) to centimeters to meters (wound dressing, fire blankets, drug delivery devices and implants). BARC hydrogel dressings have been so far used for treating burns, leprosy ulcers, animal bites, diabetic foot ulcers, herpes, fresh scars, bullet injuries, boils, pimples, sun burns, abrasion, surgical wounds of breast cancer, as bolus for radiation therapy in cancer etc. The use of gels have shown excellent result in diabetic ulcers which definitely provides an alternate to expensive biotech products and relief to expanding population of diabetics in India. Its application and some of the examples are shown in the paper. Other hydrogel based products which are under development in the authors laboratory are radiation processed silver nano-particle hydrogels to treat infected wounds and fire blankets for whole body coverage for protection from fire for defense personnel and fire service people

  18. Salphen-Co(III) complexes catalyzed copolymerization of epoxides with CO2

    Czech Academy of Sciences Publication Activity Database

    Hošťálek, Z.; Mundil, R.; Císařová, I.; Trhlíková, Olga; Grau, E.; Peruch, F.; Cramail, H.; Merna, J.

    2015-01-01

    Roč. 63, 20 April (2015), s. 52-61 ISSN 0032-3861 Institutional support: RVO:61389013 Keywords : cobalt salphen catalyst * CO2 epoxide copolymerization * MALDI-TOF Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.586, year: 2015

  19. Mechanism of alternating copolymerization of methyl methacrylate with styrene in the presence of diethylaluminum chloride

    International Nuclear Information System (INIS)

    Zubov, V.P.; Lachinov, M.B.; Ignatova, E.V.; Georgiev, G.S.; Golubev, V.B.; Kabanov, V.A.

    1982-01-01

    A kinetic study of the propagation mechanism of the alternating copolymerization of styrene (St) with methyl methacrylate (MMA) in the presence of a complexing agent (diethylaluminum chloride, DEAC) in bulk and in tetrachloroethylene solutions at a molar ratio DEAC/MMA = 0.5 has been carried out. It has been shown that the copolymerization is a chain radical process characterized by a short active-center lifetime, bimolecular termination, and high rate of chain transfer to the complexed MMA. A kinetic scheme has been proposed for the propagation mechanism of alternating copolymerization in the presence of a complexing agent not requiring independent measurements of the equilibrium constant of complexation. It has been found that spontaneous and uv-initiated copolymerizations in the system have different mechanisms of initiation and a common mechanism of propagation. The propagation proceeds by addition of single monomers as well as donor-acceptor complexes of the comonomers to the propagation radicals, with the first mechanism being predominant. Inclusion of the monomers in the complex leads to an increase of the St reactivity and to a decrease of the MMA reactivity in propagation to the corresponding macroradicals in comparison with the reactivity of the free monomers. A number of kinetic and statistical parameters of the propagation reaction have been calculated

  20. Emulsion (Co)polymerization of styrene and butyl acrylate monitored by On-line Raman Spectroscopy

    NARCIS (Netherlands)

    van den Brink, H.J.T.; Pepers, M.L.H.; Herk, van A.M.; German, A.L.

    2000-01-01

    The homo- and copolymerizations of styrene and n-butyl acrylate were studied by on-line in-situ Raman spectroscopy.Results from the solution (homo)polymerizations proved to be very useful in the quantification of the Raman data from the emulsion homopolymerization. From the homopolymerization data

  1. In-situ radiation dosimetry based on Radio-Fluorogenic Co-Polymerization

    NARCIS (Netherlands)

    Warman, J.M.; Luthjens, L.H.; De Haas, M.P.

    2009-01-01

    A fluorimetric method of radiation dosimetry is presented for which the intensity of the fluorescence of a (tissue equivalent) medium is linearly dependent on accumulated dose from a few Gray up to kiloGrays. The method is based on radio-fluorogenic co-polymerization (RFCP) in which a normally very

  2. Chemoselective alternating copolymerization of limonene dioxide and carbon dioxide : a new highly functional aliphatic epoxy polycarbonate

    NARCIS (Netherlands)

    Li, C.; Sablong, R.J.; Koning, C.E.

    The alternating copolymerization of biorenewable limonene dioxide with carbon dioxide (CO2) catalyzed by a zinc β-diiminate complex is reported. The chemoselective reaction results in linear amorphous polycarbonates that carry pendent methyloxiranes and exhibit glass transition temperatures (Tg) up

  3. Preparation of supramolecular polymers by copolymerization of monomers containing quadruple hydrogen bonding units with regular monomers

    NARCIS (Netherlands)

    2004-01-01

    The invention relates to the synthesis of polymers containing self-complementary quadruple hydrogen groups by copolymerizing monomers containing a quadruple hydrogen bonding group with one or more monomers of choice. The resulting polymers show unique new characteristics due to the presence of

  4. Graft-copolymerization of styrene on polypropylene in the solid phase

    NARCIS (Netherlands)

    Beenen, W.; VanderWal, D.; Janssen, L.P.B.M.; Buijtenhuijs, A.; Hogt, A.H.; Wal, Douwe J. v.d.

    The graft-copolymerization of styrene on PP in the solid phase has been studied under various reaction conditions using a radical initiator. Polymerization kinetics were investigated by DSC experiments and reactions in glass ampoules. The conversion rate and grafting efficiency of styrene appeared

  5. Cytocompatible cellulose hydrogels containing trace lignin

    International Nuclear Information System (INIS)

    Nakasone, Kazuki; Kobayashi, Takaomi

    2016-01-01

    Sugarcane bagasse was used as a cellulose resource to prepare transparent and flexible cellulose hydrogel films. On the purification process from bagasse to cellulose, the effect of lignin residues in the cellulose was examined for the properties and cytocompatibility of the resultant hydrogel films. The cellulose was dissolved in lithium chloride/N,N-dimethylacetamide solution and converted to hydrogel films by phase inversion. In the purification process, sodium hydroxide (NaOH) treatment time was changed from 1 to 12 h. This resulted in cellulose hydrogel films having small amounts of lignin from 1.62 to 0.68%. The remaining lignin greatly affected hydrogel properties. Water content of the hydrogel films was increased from 1153 to 1525% with a decrease of lignin content. Moreover, lower lignin content caused weakening of tensile strength from 0.80 to 0.43 N/mm"2 and elongation from 45.2 to 26.5%. Also, similar tendency was observed in viscoelastic behavior of the cellulose hydrogel films. Evidence was shown that the lignin residue was effective for the high strength of the hydrogel films. In addition, scanning probe microscopy in the morphological observation was suggested that the trace lignin in the cellulose hydrogel affected the cellulose fiber aggregation in the hydrogel network. The trace of lignin in the hydrogels also influenced fibroblast cell culture on the hydrogel films. The hydrogel film containing 1.68% lignin showed better fibroblast compatibility as compared to cell culture polystyrene dish used as reference. - Highlights: • Cellulose hydrogel films with trace lignin were obtained from sugarcane bagasse. • Lignin content was found to be in the range of 1.62 − 0.68% by UV–Vis spectroscopy. • Higher lignin content strengthened mechanical properties of the hydrogel films. • Trace lignin affected the hydrogel morphology such as roughness and porosity. • High cell proliferation was observed in the hydrogel containing 1.68% lignin.

  6. Cytocompatible cellulose hydrogels containing trace lignin

    Energy Technology Data Exchange (ETDEWEB)

    Nakasone, Kazuki; Kobayashi, Takaomi, E-mail: takaomi@nagaoakut.ac.jp

    2016-07-01

    Sugarcane bagasse was used as a cellulose resource to prepare transparent and flexible cellulose hydrogel films. On the purification process from bagasse to cellulose, the effect of lignin residues in the cellulose was examined for the properties and cytocompatibility of the resultant hydrogel films. The cellulose was dissolved in lithium chloride/N,N-dimethylacetamide solution and converted to hydrogel films by phase inversion. In the purification process, sodium hydroxide (NaOH) treatment time was changed from 1 to 12 h. This resulted in cellulose hydrogel films having small amounts of lignin from 1.62 to 0.68%. The remaining lignin greatly affected hydrogel properties. Water content of the hydrogel films was increased from 1153 to 1525% with a decrease of lignin content. Moreover, lower lignin content caused weakening of tensile strength from 0.80 to 0.43 N/mm{sup 2} and elongation from 45.2 to 26.5%. Also, similar tendency was observed in viscoelastic behavior of the cellulose hydrogel films. Evidence was shown that the lignin residue was effective for the high strength of the hydrogel films. In addition, scanning probe microscopy in the morphological observation was suggested that the trace lignin in the cellulose hydrogel affected the cellulose fiber aggregation in the hydrogel network. The trace of lignin in the hydrogels also influenced fibroblast cell culture on the hydrogel films. The hydrogel film containing 1.68% lignin showed better fibroblast compatibility as compared to cell culture polystyrene dish used as reference. - Highlights: • Cellulose hydrogel films with trace lignin were obtained from sugarcane bagasse. • Lignin content was found to be in the range of 1.62 − 0.68% by UV–Vis spectroscopy. • Higher lignin content strengthened mechanical properties of the hydrogel films. • Trace lignin affected the hydrogel morphology such as roughness and porosity. • High cell proliferation was observed in the hydrogel containing 1.68% lignin.

  7. Energy conversion in polyelectrolyte hydrogels

    Science.gov (United States)

    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).

  8. Water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qingguo, E-mail: qwang@qust.edu.cn [Key Laboratory of Rubber-Plastics of Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042 (China); Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao 266042 (China); Zhou, Xue; Zeng, Jinxia; Wang, Jizeng [Key Laboratory of Rubber-Plastics of Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042 (China)

    2016-02-01

    In this paper, the electron beam irradiation technology being more suitable for the industry application is explored to fabricate the acrylic acid (AAc) monomer-grafted polyvinyl alcohol (PVA-g-AAc) hydrogels. ATR-IR spectra of the PVA-g-AAc hydrogels shows an obvious absorption peak of the −C=O group at 1701 cm{sup −1}, indicating that the AAc monomers were grafted onto the PVA macromolecules. This paper also studied some effects of the mass ratio of PVA/AAc, pH of buffer solution and irradiation dosage on the water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels. The water swelling ratio of PVA-g-AAc hydrogels decreases with increased irradiation dosage and mass ratio of PVA/AAc, whereas swelling ratio increases with increased pH of buffer solution and soaking time. The water-swelling behavior of PVA-g-AAc hydrogels occurred easily in an alkaline environment, particularly in a buffer solution with pH 9.2. Both PVA-g-AAc hydrogels (PVA/AAc = 1/5, w/w) irradiated with 5 kilogray (kGy) and PVA-g-AAc hydrogels (PVA/AAc = 1/1, w/w) irradiated with 15 kGy could easily absorb water and lead to high water swelling ratios (up to about 600%), which are potential candidates to meet the requirements for some biomedical applications.

  9. Drug-Loadable Calcium Alginate Hydrogel System for Use in Oral Bone Tissue Repair.

    Science.gov (United States)

    Chen, Luyuan; Shen, Renze; Komasa, Satoshi; Xue, Yanxiang; Jin, Bingyu; Hou, Yepo; Okazaki, Joji; Gao, Jie

    2017-05-06

    This study developed a drug-loadable hydrogel system with high plasticity and favorable biological properties to enhance oral bone tissue regeneration. Hydrogels of different calcium alginate concentrations were prepared. Their swelling ratio, degradation time, and bovine serum albumin (BSA) release rate were measured. Human periodontal ligament cells (hPDLCs) and bone marrow stromal cells (BMSCs) were cultured with both calcium alginate hydrogels and polylactic acid (PLA), and then we examined the proliferation of cells. Inflammatory-related factor gene expressions of hPDLCs and osteogenesis-related gene expressions of BMSCs were observed. Materials were implanted into the subcutaneous tissue of rabbits to determine the biosecurity properties of the materials. The materials were also implanted in mandibular bone defects and then scanned using micro-CT. The calcium alginate hydrogels caused less inflammation than the PLA. The number of mineralized nodules and the expression of osteoblast-related genes were significantly higher in the hydrogel group compared with the control group. When the materials were implanted in subcutaneous tissue, materials showed favorable biocompatibility. The calcium alginate hydrogels had superior osteoinductive bone ability to the PLA. The drug-loadable calcium alginate hydrogel system is a potential bone defect reparation material for clinical dental application.

  10. A high efficacy antimicrobial acrylate based hydrogels with incorporated copper for wound healing application

    Energy Technology Data Exchange (ETDEWEB)

    Vuković, Jovana S.; Babić, Marija M.; Antić, Katarina M.; Miljković, Miona G.; Perić-Grujić, Aleksandra A.; Filipović, Jovanka M.; Tomić, Simonida Lj., E-mail: simonida@tmf.bg.ac.rs

    2015-08-15

    In this study, three series of hydrogels based on 2-hydroxyethyl acrylate and itaconic acid, unloaded, with incorporated copper(II) ions and reduced copper, were successfully prepared, characterized and evaluated as novel wound healing materials. Fourier transform infrared spectroscopy (FTIR) confirmed the expected structure of obtained hydrogels. Scanning electron microscopy (SEM) revealed porous morphology of unloaded hydrogels, and the morphological modifications in case of loaded hydrogels. Thermal characteristics were examined by differential scanning calorimetry (DSC) and the glass transition temperatures were observed in range of 12–50 °C. Swelling study was conducted in wide range of pHs at 37 °C, confirming pH sensitive behaviour for all three series of hydrogels. The in vitro copper release was investigated and the experimental data were analysed using several models in order to elucidate the transport mechanism. The antimicrobial assay revealed excellent antimicrobial activity, over 99% against Escherichia coli, Staphylococcus aureus and Candida albicans, as well as good correlation with the copper release experiments. In accordance with potential application, water vapour transmission rate, oxygen penetration, dispersion characteristics, fluid retention were observed and the suitability of the hydrogels for wound healing application was discussed. - Graphical abstract: Display Omitted - Highlights: • Design and evaluation of novel pH responsive hydrogel series. • Structural, morphological, thermal characterization and controlled copper release. • Antibacterial activity against Escherichia coli and Staphylococcus aureus over 99%. • Antifungal activity against Candida albicans over 99%. • In vitro evaluation studies revealed great potential for wound healing application.

  11. Amphotericin B-conjugated polypeptide hydrogels as a novel innovative strategy for fungal infections

    Science.gov (United States)

    Shu, Chang; Li, Tengfei; Yang, Wen; Li, Duo; Ji, Shunli; Ding, Li

    2018-03-01

    The present work is focused on the design and development of novel amphotericin B (AmB)-conjugated biocompatible and biodegradable polypeptide hydrogels to improve the antifungal activity. Using three kinds of promoting self-assembly groups (2-naphthalene acetic acid (Nap), naproxen (Npx) and dexamethasone (Dex)) and polypeptide sequence (Phe-Phe-Asp-Lys-Tyr, FFDKY), we successfully synthesized the Nap-FFDK(AmB)Y gels, Npx-FFDK(AmB)Y gels and Dex-FFDK(AmB)Y gels. The AmB-conjugated hydrogelators are highly soluble in different aqueous solutions. The cryo-transmission electron microscopy and scanning electron microscopy micrographs of hydrogels afford nanofibres with a width of 20-50 nm. Powder X-ray diffraction analyses demonstrate that the crystalline structures of the AmB and Dex are changed into amorphous structures after the formation of hydrogels. Circular dichroism spectra of the solution of blank carriers and the corresponding drug deliveries further help elucidate the molecular arrangement in gel phase, indicating the existence of turn features. The in vitro drug releases suggest that the AmB-conjugated hydrogels are suitable as drug-controlled release vehicles for hydrophobic drugs. The antifungal effect of AmB-conjugated hydrogels significantly exhibits the antifungal activity against Candida albicans. The results of the present study indicated that the AmB-conjugated hydrogels are suitable carriers for poorly water soluble drugs and for enhancement of therapeutic efficacy of antifungal drugs.

  12. Hydrogels in Miniemulsions

    Science.gov (United States)

    Landfester, Katharina; Musyanovych, Anna

    In the last decade, the synthesis of polymeric materials that respond to specific environment stimuli by changing their size has attracted widespread interest in both fundamental and applied areas of research. Hydrogels in dispersions are composed of randomly oriented, physically or chemically crosslinked hydrophilic or amphiphilic polymer chains. The synthesis of these gels at the nanoscale (nanogels or microgels) is especially of great importance for their application in drug delivery and controlled release systems, and in biomimetics, biosensing, tissue regeneration, heterogeneous catalysis, etc. The focus of this review is to present the versatility of the miniemulsion process for the formation of monodisperse nanogels from synthetic and natural polymers. Several applications of the obtained microgels are briefly described.

  13. Alginate-Collagen Fibril Composite Hydrogel

    Directory of Open Access Journals (Sweden)

    Mahmoud Baniasadi

    2015-02-01

    Full Text Available We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  14. Tri-n-Butylborane/WaterComplex-Mediated Copolymerization of Methyl Methacrylate with Proteinaceous Materials and Proteins: A Review

    Directory of Open Access Journals (Sweden)

    Yoshinori Kadoma

    2010-11-01

    Full Text Available Previous studies of tri-n-butylborane–initiated graft copolymerization of methyl methacrylates with hydrated proteinous materials and proteins have focused on the number of grafted-poly (MMA branches as well as the percent graft and graft efficiency. The number of branches in silk fibroin is 1.3, whereas the number in collagen, gelatin, ovalbumin and wool are 0.1, 0.04, 0.02 and 0.03, respectively. The number of grafted-PMMA branches in synthetic poly-L-peptides is approximately 10-fold less than that in gelatin, and decline, in the order poly-Ala > poly-Ser > poly-Pro > poly-Glu > poly-Lys. By contrast, poly-Gly, poly-Tyr and poly-Leu have no branches. The co-catalytic effect (the ratio of the number of polymer formed relative to that of control of amino acids on tri-n-butylborane-initiated polymerization of MMA in the presence of water has been linearly correlated with their ionization potential (IPkoopman; |Äå HOMO (Highest Occupied Molecular Orbital| (r2 = 0.6, outliers: Cys and His; Äå HOMO = [åHOMOaqua − åHOMOvacuum] calculated using the semiempirical AM1 method. Also, a significant exponential relationship between the number of branches of poly-L-polypeptides and the Äå HOMO of the corresponding amino acids has been observed (r2 = 0.9. A possible grafting site of protein (polypeptide is discussed.

  15. Characterization of polyethyleneterephthalate (PET) based proton exchange membranes prepared by UV-radiation-induced graft copolymerization of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Mostak; Khan, Mohammad B.; Alam, S. Shamsul; Khan, M. Anwar H. [Department of Chemistry, Shahjalal University of Science and Technology, Sylhet 3114 (Bangladesh); Khan, Mubarak A. [Radiation and Polymer Chemistry Laboratory, Institute of Nuclear Science and Technology, Bangladesh Atomic Energy Commission, P.O. Box 3787, Dhaka (Bangladesh); Halim, Md. Abdul [Department of Chemistry, Jahangirnagar University, savar, Dhaka (Bangladesh)

    2011-01-15

    Polymer electrolyte membranes (PEMs) were successfully prepared by simultaneous ultraviolet (UV) radiation-induced graft copolymerization of styrene (35 vol.% concentration) onto poly(ethyleneterephthalate) (PET) film, followed by sulfonation on the styrene monomer units in the grafting chain using 0.05 M chlorosulfonic acid (ClSO{sub 3}H). The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as Fourier Transform Infrared (FTIR) spectroscopy. The maximum ion-exchange capacity (IEC) of the PEM was measured to be 0.04385 mmol g{sup -1} at its highest level of grafting and sulfonation. They exhibited high thermal and mechanical properties as well as oxidative stability. They are highly stable in H{sub 2}SO{sub 4} solutions and can be used in the acidic fuel cells. The membranes showed low water uptake as well as low proton conductivity than Nafion. In this study, the preparation of PEMs from commodity-type polymers is found to be very inexpensive and is a suitable candidate for applications in fuel cells. (author)

  16. Stable and pH-responsive core-shell nanoparticles based on HEC and PMAA networks via template copolymerization

    Science.gov (United States)

    Zhang, Y.; Jin, Q.; Chen, Y.; Zhao, J.

    2011-10-01

    Taking advantage of the specific hydrogen bonding interactions, stable and pH-responsive core-shell nanoparticles based on hydroxyethyl cellulose (HEC) and polymethacrylic acid (PMAA) networks, with a size ranging from 190 to 250 nm, can be efficiently prepared via facile one-step co-polymerization of methacrylic acid (MAA) and N, N'-methylenebisacrylamide (MBA) on HEC template in water. Using dynamic light scattering, electrophoretic light scattering, fluorescence spectrometry, thermo-gravimetric analysis, TEM, and AFM observations, the influence of crosslinker MBA as well as the reaction parameters were studied. The results show that after the introduction of crosslinker MBA, the nanoparticles became less compact; their size exhibited a smaller pH sensitivity, and their stability against pH value was improved greatly. Furthermore, the size, structure, and pH response of the nanoparticles can be adjusted via varying the reaction parameters: nanoparticles of smaller size, more compact structure, and higher swelling capacity were produced as pH value of the reaction medium increased or the HEC/MAA ratio decreased; while nanoparticles of smaller size, less compact structure and smaller swelling capacity were produced as the total feeding concentration increased.

  17. Synthesis of porous poly(acrylamide hydrogels using calcium carbonate and its application for slow release of potassium nitrate

    Directory of Open Access Journals (Sweden)

    2009-05-01

    Full Text Available Porous poly(acrylamide was synthesized using calcium carbonate microparticles and subsequent acid treatment to remove the calcium carbonate. Methylenebisacrylamide and ammonium persulfate/sodium metabisulfite were used as crosslinking agent and redox initiator, respectively. The porous structure of resulted hydrogels was confirmed using SEM micrographs. The effect of methylenebisacrylamide concentration and calcium carbonate amount on the swelling of the hydrogels was investigated. The results showed that the effect of methylenebisacrylamide and calcium carbonate variables on the swelling is reverse. The hydrogels were subsequently utilized for the loading of potassium nitrate. Potassium nitrate as active agent was loaded into hydrogels and subsequently the release of this active agent was investigated. In these series of investigation, the effect of content of loading, methylenebisacrylamide and calcium carbonate amount on the release of potassium nitrate from hydrogels was investigated.

  18. Flexible pH-Sensing Hydrogel Fibers for Epidermal Applications.

    Science.gov (United States)

    Tamayol, Ali; Akbari, Mohsen; Zilberman, Yael; Comotto, Mattia; Lesha, Emal; Serex, Ludovic; Bagherifard, Sara; Chen, Yu; Fu, Guoqing; Ameri, Shideh Kabiri; Ruan, Weitong; Miller, Eric L; Dokmeci, Mehmet R; Sonkusale, Sameer; Khademhosseini, Ali

    2016-03-01

    Epidermal pH is an indication of the skin's physiological condition. For example, pH of wound can be correlated to angiogenesis, protease activity, bacterial infection, etc. Chronic nonhealing wounds are known to have an elevated alkaline environment, while healing process occurs more readily in an acidic environment. Thus, dermal patches capable of continuous pH measurement can be used as point-of-care systems for monitoring skin disorder and the wound healing process. Here, pH-responsive hydrogel fibers are presented that can be used for long-term monitoring of epidermal wound condition. pH-responsive dyes are loaded into mesoporous microparticles and incorporated into hydrogel fibers using a microfluidic spinning system. The fabricated pH-responsive microfibers are flexible and can create conformal contact with skin. The response of pH-sensitive fibers with different compositions and thicknesses are characterized. The suggested technique is scalable and can be used to fabricate hydrogel-based wound dressings with clinically relevant dimensions. Images of the pH-sensing fibers during real-time pH measurement can be captured with a smart phone camera for convenient readout on-site. Through image processing, a quantitative pH map of the hydrogel fibers and the underlying tissue can be extracted. The developed skin dressing can act as a point-of-care device for monitoring the wound healing process. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Tough and Conductive Hybrid Hydrogels Enabling Facile Patterning.

    Science.gov (United States)

    Zhu, Fengbo; Lin, Ji; Wu, Zi Liang; Qu, Shaoxing; Yin, Jun; Qian, Jin; Zheng, Qiang

    2018-04-25

    Conductive polymer hydrogels (CPHs) that combine the unique properties of hydrogels and electronic properties of conductors have shown their great potentials in wearable/implantable electronic devices, where materials with remarkable mechanical properties, high conductivity, and easy processability are demanding. Here, we have developed a new type of polyion complex/polyaniline (PIC/PAni) hybrid hydrogels that are tough, conductive, and can be facilely patterned. The incorporation of conductive phase (PAni) into PIC matrix through phytic acid resulted in hybrid gels with ∼65 wt % water; high conductivity while maintaining the key viscoelasticity of the tough matrix. The gel prepared from 1 M aniline (Ani) exhibited the breaking strain, fracture stress, tensile modulus, and electrical conductivity of 395%, 1.15 MPa, 5.31 MPa, and 0.7 S/m, respectively, superior to the most existing CPHs. The mechanical and electrical performance of PIC/PAni hybrid hydrogels exhibited pronounced rate-dependent and self-recovery behaviors. The hybrid gels can effectively detect subtle human motions as strain sensors. Alternating conductive/nonconductive patterns can be readily achieved by selective Ani polymerization using stencil masks. This facile patterning method based on PIC/PAni gels can be readily scaled up for fast fabrication of wavy gel circuits and multichannel sensor arrays, enabling real-time monitoring of the large-extent and large-area deformations with various sensitivities.

  20. Proliferation and osteoblastic differentiation of hMSCs on cellulose-based hydrogels.

    Science.gov (United States)

    Raucci, Maria Grazia; Alvarez-Perez, Marco Antonio; Demitri, Christian; Sannino, Alessandro; Ambrosio, Luigi

    2012-01-01

    The aim of this project was to study the proliferation and differentiation of human Mesenchymal Stem Cells (hMSCs) onto a cellulose-based hydrogel for bone tissue engineering. Modified-cellulose hydrogel was prepared via double esterification crosslinking using citric acid. The response of human Mesenchymal Stem Cells (hMSCs) in terms of cell proliferation and differentiation into osteoblastic phenotype was evaluated by using Alamar blue assay and Alkaline phosphatase activity. The results showed that CMCNa and CMCNa_CA have no negative effect on hMSC, adhesion and proliferation. Moreover, the increase of the ALP expression for CMCNa_CA confirms the ability of the hydrogels to support the osteoblastic differentiation. The cellulose-based hydrogels have a potential application as filler in bone tissue regeneration.

  1. Kinetic Degradation and Controlled Drug Delivery System Studies for Sensitive Hydrogels Prepared by Gamma Irradiation

    International Nuclear Information System (INIS)

    Eid, M.; El-Arnaouty, M.B.

    2008-01-01

    Ternary mixtures of N-vinyle-2-pyrrolidone(NVP ), itaconic acid (IA) and gelatin (G) were gamma irradiated to prepared poly(NVP/IA/G) hydrogels. The equilibrium kinetic swelling, drug release behavior, Scan Electron Microscope (SEM) and the swelling-degradation kinetics were studied. Both the diffusion exponent and the diffusion coefficient increase with increasing content of (IA). Also, the swelling behavior of copolymer hydrogels in response to ph value of the external media was studied, it is noted that the highest swelling values at ph 4. The in vitro drug release behavior of these hydrogels was examined by quantification analysis with a UV/VIS spectrophotometers. Chlorpromazine hydrochloride was loaded into dried hydrogels to investigate the stimuli-sensitive property at the specific ph. The release studies show that the highest value of release was at ph 4 which can be used for drug delivery system

  2. Design and development of guar gum based novel, superabsorbent and moisture retaining hydrogels for agricultural applications.

    Science.gov (United States)

    Thombare, Nandkishore; Mishra, Sumit; Siddiqui, M Z; Jha, Usha; Singh, Deodhari; Mahajan, Gopal R

    2018-04-01

    The novel hydrogels were synthesized by grafting guar gum with acrylic acid and cross-linking with ethylene glycol di methacrylic acid (EGDMA). The synthesis of hydrogel was confirmed by characterization through 13 C NMR, FTIR spectroscopy, SEM micrography, thermo-gravimetric analysis and water absorption studies under different solutions. Synthesized hydrogel (GG-AA-EGDMA) was confirmed to be biodegradable with half-life period of 77 days through soil burial biodegradation studies. The effects of hydrogel treatment on soil were evaluated by studying various physico-chemical properties of soil like bulk density, porosity, water absorption and retention capacity etc. The hydrogel which could absorb up to 800 ml water per gram, after addition to soil, improved its porosity, moisture absorption and retention capacity significantly. Water holding capacity of water increased up to 54% of its original and porosity also increased up to 9% of its original. The synthesized hydrogel revealed tremendous potential as soil conditioning material for agricultural applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Novel Hydrogels from Renewable Resources

    Science.gov (United States)

    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

  4. Preparation and characterization of a hydrogel carrier to deliver gatifloxacin and its application as a therapeutic contact lens for bacterial keratitis therapy

    International Nuclear Information System (INIS)

    Shi, Yunfeng; Fu, Yeyun; Ma, Dong; Xue, Wei; Lv, Hongling; Lu, Qingjun; Zhong, Jingxiang; Huang, Yuexin

    2013-01-01

    A soft and biocompatible hydrogel exhibiting a higher loading and the sustained release of gatifloxacin (GFLX) was developed as the potential matrix to fabricate a therapeutic contact lens for curing bacterial keratitis. 2-hydroxyethyl methacrylate (HEMA) and five other kinds of vinyl monomers with different side groups were used as co-monomers. Copolymerization took place in a cornea shaped mould via the gradient temperature-elevating method. The results of drug loading and in vitro release experiments showed that P(HEMA-co-MAA) achieved the highest drug loading of 11.78±0.77 µg mg −1 among the obtained hydrogels, as well as a slow release. In addition, its physical properties and cytocompatibility were also proved suitable and safe for wearing on the eye surface. In animal experiments, a rat model of bacterial keratitis was established and employed to evaluate the clinical results of certain treatments employing obtained hydrogels; saline and GFLX eye drops were used as negative and positive controls, respectively. Corneal abscess and opacity caused by epithelial erosion and stromal ulceration were almost healed after wearing the drug loaded P(HEMA-co-MAA) hydrogel for 48 h. Its excellent antibacterial effect was also confirmed by testing the bacterial activity in tear extraction via the streak line method. (paper)

  5. Anisotropic dehydration of hydrogel surfaces.

    Science.gov (United States)

    Kaklamani, Georgia; Cheneler, David; Grover, Liam M; Adams, Michael J; Anastasiadis, Spiros H; Bowen, James

    2017-12-01

    Efforts to develop tissue-engineered skin for regenerative medicine have explored natural, synthetic, and hybrid hydrogels. The creation of a bilayer material, with the stratification exhibited by native skin, is a complex problem. The mechanically robust, waterproof epidermis presents the stratum corneum at the tissue/air interface, which confers many of these protective properties. In this work, we explore the effect of high temperatures on alginate hydrogels, which are widely employed for tissue engineering due to their excellent mechanical properties and cellular compatibility. In particular, we investigate the rapid dehydration of the hydrogel surface which occurs following local exposure to heated surfaces with temperatures in the range 100-200 °C. We report the creation of a mechanically strengthened hydrogel surface, with improved puncture resistance and increased coefficient of friction, compared to an unheated surface. The use of a mechanical restraint during heating promoted differences in the rate of mass loss; the rate of temperature increase within the hydrogel, in the presence and absence of restraint, is simulated and discussed. It is hoped that the results will be of use in the development of processes suitable for preparing skin-like analogues; application areas could include wound healing and skin restoration.

  6. STYRENE/STYRENE-DERIVATIVE COPOLYMERIZATION BY PH2Zn-METALLOCENE-MAO SYSTEMS: HOMO- AND COPOLYMERIZATION OF á-METHYLSTYRENE WITH STYRENE

    OpenAIRE

    RABAGLIATI, FRANCO M; MUÑOZ, HÉCTOR E; MARDONES, GABRIELA V

    2010-01-01

    The copolymerization of styrene with á-methylstyrene has been tested using combined metallocene-MAO initiator systems with and without diphenylzinc. The metallocenes used were biscyclopentadienyltitanium dichloride, Cp2TiCl2, bis(n-butylcyclopentadienyl)titanium dichloride, (n-BuCp)2TiCl2, and the half-sandwich metallocene indenyltitanium trichloride, IndTiCl3. The results indicate that both binary metallocene-MAO, and ternary Ph2Zn-metallocene-MAO systems are capable of polymerizing á-methyl...

  7. Type II collagen-hyaluronan hydrogel – a step towards a scaffold for intervertebral disc tissue engineering

    Directory of Open Access Journals (Sweden)

    L Calderon

    2010-09-01

    Full Text Available Intervertebral disc regeneration strategies based on stem cell differentiation in combination with the design of functional scaffolds is an attractive approach towards repairing/regenerating the nucleus pulposus. The specific aim of this study was to optimise a composite hydrogel composed of type II collagen and hyaluronic acid (HA as a carrier for mesenchymal stem cells. Hydrogel stabilisation was achieved by means of 1-ethyl-3(3-dimethyl aminopropyl carbodiimide (EDC and N-hydroxysuccinimide (NHS cross-linking. Optimal hydrogel properties were determined by investigating different concentrations of EDC (8mM, 24mM and 48mM. Stable hydrogels were obtained independent of the concentration of carbodiimide used. The hydrogels cross-linked by the lowest concentration of EDC (8mM demonstrated high swelling properties. Additionally, improved proliferation of seeded rat mesenchymal stem cells (rMSCs and hydrogel stability levels in culture were observed with this 8mM cross-linked hydrogel. Results from this study indicate that EDC/NHS (8mM cross-linked type II collagen/HA hydrogel was capable of supporting viability of rMSCs, and furthermore their differentiation into a chondrogenic lineage. Further investigations should be conducted to determine its potential as scaffold for nucleus pulposus regeneration/repair.

  8. Hydrogels from feather keratin show higher viscoelastic properties and cell proliferation than those from hair and wool keratins.

    Science.gov (United States)

    Esparza, Yussef; Bandara, Nandika; Ullah, Aman; Wu, Jianping

    2018-09-01

    Hydrogel prepared from keratin shows potential applications in tissue engineering. However, the importance of the keratin sources has not been considered. The objectives of this study were to characterize and compare the rheological (storage modulus), physical (porosity, pore size, swelling capacity, and water contact angle) and in vitro cell compatibility of hydrogel scaffolds prepared from various keratin sources. Keratins were characterized by means of their molecular weight, amino acid composition, thermal and conformational properties. Hydrogels from chicken feather keratins demonstrated substantially higher storage modulus (G') than hair and wool keratin hydrogels. However, higher swelling capacity (>3000%) was determined in hair and wool over feather keratin (1500%) hydrogels. Our results suggest that small molecular weight and β-sheet conformation of feather keratin (~10 kDa) facilitated the self-assembly of rigid hydrogels through disulfide bond re-oxidation. Whereas, high molecular weight (10-75 kDa) stretchable α-helix conformation in hair and wool keratins resulted in weaker hydrogels. The cell cultures using fibroblasts showed the highest proliferation rate on chicken feather keratin hydrogel scaffolds. After 15 days of culture, partial breakdown of keratin fibers was observed. Results indicate that stiffer avian keratins can be used to fabricate more mechanically robust biomaterials than mammalian keratins. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Water- and Fertilizer-Integrated Hydrogel Derived from the Polymerization of Acrylic Acid and Urea as a Slow-Release N Fertilizer and Water Retention in Agriculture.

    Science.gov (United States)

    Cheng, Dongdong; Liu, Yan; Yang, Guiting; Zhang, Aiping

    2018-05-31

    To reduce the preparation cost of superabsorbent and improve the N release rate at the same time, a novel low-cost superabsorbent (SA) with the function of N slow release was prepared by chemical synthesis with neutralized acrylic acid (AA), urea, potassium persulfate (KPS), and N, N'-methylenebis(acrylamide) (MBA). The order of influence factors on the water absorbency property was determined by an orthogonal L 18 (3) 7 experiment. On the basis of the optimization results of the orthogonal experiment, the effects of a single factor on the water absorption were investigated, and the highest water absorbency (909 g/g) was achieved for the conditions of 1.0 mol urea/mol AA ratio, 100% of AA neutralized, K + , 1.5% KPS to AA mass fraction, 0.02% MBA to AA mass fraction, 45 °C reaction temperature, and 4.0 h reaction time. The optimal sample was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behaviors of the superabsorbent were investigated in distilled water and various soil and salt solutions. The water-release kinetics of SA in different negative pressures and soils were systematically investigated. Additionally, the maize seed germination in various types of soil with different amounts of SA was proposed, and the N could release 3.71% after being incubated in distilled water for 40 days. After 192 h, the relative water content of SA-treated sandy loam, loam, and paddy soil were 42, 56, and 45%, respectively. All of the results in this work showed that SA had good water retention and slow N-release properties, which are expected to have potential applications in sustainable modern agriculture.

  10. Electrochemical characterization of hydrogels for biomimetic applications

    DEFF Research Database (Denmark)

    Peláez, L.; Romero, V.; Escalera, S.

    2011-01-01

    ) or a photoinitiator (P) to encapsulate and stabilize biomimetic membranes for novel separation technologies or biosensor applications. In this paper, we have investigated the electrochemical properties of the hydrogels used for membrane encapsulation. Specifically, we studied the crosslinked hydrogels by using...... electrochemical impedance spectroscopy (EIS), and we demonstrated that chemically crosslinked hydrogels had lower values for the effective electrical resistance and higher values for the electrical capacitance compared with hydrogels with photoinitiated crosslinking. Transport numbers were obtained using......〉 and 〈Pw〉 values than PEG‐1000‐DMA‐P and PEG‐400‐DA‐P hydrogels. In conclusion, our results show that hydrogel electrochemical properties can be controlled by the choice of polymer and type of crosslinking used and that their water and salt permeability properties are congruent with the use of hydrogels...

  11. Selective Release of anti–TB Drugs Complex from Smart Copolymeric Bioactive nano–carriers

    Directory of Open Access Journals (Sweden)

    Alejandro Arredondo–Peñaranda

    2014-07-01

    Full Text Available Smart nano–copolymeric matrices have been employed to load and release anti tuberculosis (anti – TB drugs combinated complexes of Ethambutol (EMB, Isoniazid (INH, Rifampicin (RMP and Pyrazinamide (PZA. Copolymeric nanocarriers were synthesized using a microemulsion polymerization method previously reported. These nanocarriers can show selective swelling–collapse response under changes in local environments such a temperature, pH, solvent composition and electrical stimuli. The employ of these kinds of systems permits a controlled and selective delivery and release on specific human tissues. High Performance Liquid Chromatography technique was used to allow the detection of combinated mixtures of different active principles of anti–TB drugs using an acetonitrile mobile phase at 0.5 mL/min of flow rate whit a Spherisorb ODS2, C18 column. The results obtained suggest that the employ of smart nanohydrogels is a novel method in several tuberculosis therapies.

  12. Synthesis, Cyclopolymerization and Cyclo-Copolymerization of 9-(2-Diallylaminoethyladenine and Its Hydrochloride Salt

    Directory of Open Access Journals (Sweden)

    Karyn Usher

    2012-11-01

    Full Text Available We report herein the synthesis and characterization of 9-(2-diallylaminoethyl adenine. We evaluated two different synthetic routes starting with adenine where the optimal route was achieved through coupling of 9-(2-chloroethyladenine with diallylamine. The cyclopolymerization and cyclo-copolymerization of 9-(2-diallylaminoethyladenine hydrochloride salt resulted in low molecular weight oligomers in low yields. In contrast, 9-(2-diallylaminoethyladenine failed to cyclopolymerize, however, it formed a copolymer with SO2 in relatively good yields. The molecular weights of the cyclopolymers were around 1,700–6,000 g/mol, as estimated by SEC. The cyclo-copolymer was stable up to 226 °C. To the best of our knowledge, this is the first example of a free-radical cyclo-copolymerization of a neutral alkyldiallylamine derivative with SO2. These polymers represent a novel class of carbocyclic polynucleotides.

  13. Radiation-induced emulsion copolymerization of vinyl chloride with vinyl acetate in an engineering flow system

    International Nuclear Information System (INIS)

    Tsai, J.T.; Stahel, E.P.; Stannett, V.T.

    1979-01-01

    A flow reactor system was used to study the radiation-induced emulsion copolymerization of vinyl chloride with vinyl acetate. The emulsion was recirculated from a stirred vessel through transfer lines to a tubular reactor located within a high-intensity Co-60 source. The effects of physical chemical variables such as soap concentration, phase ratio, reaction temperature and residence time distribution on the molecular weight properties were investigated. The rate of copolymerization was found to be proportional to the 0.17 power of the soap concentration. Variation of the monomer-water ratio produced no significant change in rate. The rate increased with an increase in temperature over the range 5 to 50 0 C, while the average molecular weights of the copolymer increased with decreasing polymerization temperature. The molecular weight distribution in this engineering system was found to be essentially similar to those produced in a batch system

  14. The radiation-induced copolymerization of vinyl acetate with dibutyl maleate

    International Nuclear Information System (INIS)

    Du Plessis, T.A.; Lustig, A.

    1975-01-01

    The radiation-induced copolymerization of vinyl acetate with dibutyl maleate was investigated in the temperature range from -50 0 to 90 0 . A copolymer of the unsaturated ester with vinyl acetate was obtained in which the comonomers alternate with regularity along the polymer chain over the entire range of comonomer compositions and temperature range investigated. Both the rate of copolymerization and the molecular weight of the resulting copolymer were found to depend strongly on the comonomer composition. The monomer reactivity ratios were found to be practically zero. The apparent activation energy was found to change at 5 0 with an increase in temperature from a value of 1,6 kcal/mole to a value of 4,4kcal/mole. Scavenger studies indicate that a free radical mechanism prevails over the entire temperature range investigated. (Author) [af

  15. Catalytic copolymerization of CO and ethylene with a charge neutral palladium(II) zwitterion.

    Science.gov (United States)

    Lu, Connie C; Peters, Jonas C

    2002-05-15

    The synthesis of a zwitterionic Pd(II) complex supported by an anionic bis(phosphino)borate ligand, Ph(2)B(CH(2)PPh(2))(2) (abbreviated as [Ph(2)BP(2)]), is reported. The new complex, [Ph(2)BP(2)]PdMe(THF), is active for CO and ethylene copolymerization. The copolymerization activity and polyketone molecular weight for the neutral, zwitterionic system are compared with those for the cationic systems [R(2)E(CH(2)PPh(2))(2)PdMe(THF)][B(C(6)F(5))(4)] where ER(2) = SiPh(2) and CH(2). Surprisingly, the more electron rich zwitterionic system is a catalyst of activity comparable to that of the more conventional cationic systems.

  16. Radiation graft copolymerization of n-butyl acrylate on natural rubber latex

    International Nuclear Information System (INIS)

    Sundardi, F.; Kadariah, S.

    1986-01-01

    A method of radiation graft copolymerization of n-butyl acrylate (NBA) on natural rubber (NR) latex has been studied. The rate of conversion increases with the increase of NBA in latex. An irradiation dose of about 12 kGy is needed to obtain 90% conversion with 40 phr of NBA in latex. Tensile strength, tear strength, and elongation at break of grafted NR are found to decrease with increasing degree of grafting. The physical strength of a vulcanizate prepared from a mixture of NR and ply-NBA was found to be better than that of NBA-NR graft copolymer vulcanizate. The graft copolymerization reaction takes place in the outer layer of NR particles, and because the secondary bonds between poly-NBA molecules may be weaker than those between NR molecules, the existence of a poly-NBA layer in NR particles will decrease its physical strength

  17. Hydrogels and their medical applications

    Science.gov (United States)

    Rosiak, Janusz M.; Yoshii, Fumio

    1999-05-01

    Biomaterials play a key role in most approaches for engineering tissues as substitutes for functional replacement, for components of devices related to therapy and diagnosis, for drug delivery systems and supportive scaffolds for guided tissue growth. Modern biomaterials could be composed of various components, e.g. metals, ceramics, natural tissues, polymers. In this last group, the hydrogels, hydrophilic polymeric gels with requested biocompatibility and designed interaction with living surrounding seem to be one of the most promising group of biomaterials. Especially, if they are formed by means of ionizing radiation. In early 1950s, the pioneers of the radiation chemistry of polymers began some experiments with radiation crosslinking of hydrophilic polymers. However, hydrogels were analyzed mainly from the point of view of the phenomenon associated with radiation synthesis, with topology of network and relation between radiation parameters of the processes. Fundamental monographs on radiation polymer physics and chemistry written by A. Charlesby (Atomic Radition and polymers, Pergamon Press, Oxford, 1960) and A. Chapiro (Radiation Chemistry of Polymeric Systems, Interscience, New York, 1962) proceed from this time. The noticeable interest in the application of radiation techniques to obtain hydrogels for biomedical purposes began in the late sixties as a result of the papers and patents invented by Japanese and American scientists, headed by Kaetsu in Japan and Hoffman in USA. Immobilization of biologically active species in hydrogel matrices, their use as drug delivery systems and enzyme traps as well as the modification of material surfaces to improve biocompatibility and their ability to bond antigens and antibodies had been the main subjects of these investigations. In this article a brief summary of investigations on mechanism and kinetics of radiation formation of hydrogels as well as some examples of commercialized hydrogel biomaterials have been

  18. Hydrogels and their medical applications

    International Nuclear Information System (INIS)

    Rosiak, Janusz M.; Yoshii, Fumio

    1999-01-01

    Biomaterials play a key role in most approaches for engineering tissues as substitutes for functional replacement, for components of devices related to therapy and diagnosis, for drug delivery systems and supportive scaffolds for guided tissue growth. Modern biomaterials could be composed of various components, e.g. metals, ceramics, natural tissues, polymers. In this last group, the hydrogels, hydrophilic polymeric gels with requested biocompatibility and designed interaction with living surrounding seem to be one of the most promising group of biomaterials. Especially, if they are formed by means of ionizing radiation. In early 1950s, the pioneers of the radiation chemistry of polymers began some experiments with radiation crosslinking of hydrophilic polymers. However, hydrogels were analyzed mainly from the point of view of the phenomenon associated with radiation synthesis, with topology of network and relation between radiation parameters of the processes. Fundamental monographs on radiation polymer physics and chemistry written by A. Charlesby (Atomic Radition and polymers, Pergamon Press, Oxford, 1960) and A. Chapiro (Radiation Chemistry of Polymeric Systems, Interscience, New York, 1962) proceed from this time. The noticeable interest in the application of radiation techniques to obtain hydrogels for biomedical purposes began in the late sixties as a result of the papers and patents invented by Japanese and American scientists, headed by Kaetsu in Japan and Hoffman in USA. Immobilization of biologically active species in hydrogel matrices, their use as drug delivery systems and enzyme traps as well as the modification of material surfaces to improve biocompatibility and their ability to bond antigens and antibodies had been the main subjects of these investigations. In this article a brief summary of investigations on mechanism and kinetics of radiation formation of hydrogels as well as some examples of commercialized hydrogel biomaterials have been

  19. Radiation induced copolymerization of N-vinyl-2-pyrrolidone with vinyl acetate [Paper No. RD-3

    International Nuclear Information System (INIS)

    Ramakrishna, M.S.; Dhal, P.K.; Deshpande, D.D.; Babu, G.N.

    1982-01-01

    Copolymerization of N-vinyl-2-pyrrolidone (NVP) with vinyl acetate (VAC) was carried out using gamma-ray radiation. The compositions of the copolymers were determined from elemental analysis and the monomer reactivity ratios have been calculated using YBR method. The glass transition temperature and the intrinsic viscosities of the copolymers have been determined. All the experimental results were discussed in terms of the nature of the monomers. (author)

  20. Copolymerization preparation of cationic cyclodextrin chiral stationary phases for drug enantioseparation in chromatography

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Ren-Qi Wang, Teng-Teng Ong, Ke Huang, Weihua Tang & Siu-Choon Ng ### Abstract We described a facile and effective protocol wherein radical copolymerization is employed to covalently bond cationic β-cyclodextrin (β-CD) onto silica particles with extended linkage, resulting in a chiral stationary phase (IMPCSP) that can be used for the enantioseparation of racemic drugs in both high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). Starting ...

  1. A peptidic hydrogel that may behave as a “Trojan Horse”

    Directory of Open Access Journals (Sweden)

    Nicola Castellucci

    2013-02-01

    Full Text Available A physical hydrogel prepared with the low-molecular-weight hydrogelator (LMWHG CH2(C3H6CO-L-Phe-D-Oxd-OH2 and water/ethanol mixture was applied as a potential “Trojan Horse” carrier into cells. By SEM and XRD analysis we could demonstrate that a fibrous structure is present in the xerogel, making a complex network. The gelator is derived from α-amino acids (Thr, Phe and a fatty acid (azelaic acid and is biocompatible: it was dosed to IGROV-1 cells, which internalized it, without significantly affecting the cell proliferation. To check the internalization process by confocal microscopy, fluorescent hydrogels were prepared, introducing the fluorescent dansyl moiety into the mixture.

  2. Development of a P((MAA-co-NVP)-g-EG) Hydrogel Platform for Oral Protein Delivery: Effects of Hydrogel Composition on Environmental Response and Protein Partitioning.

    Science.gov (United States)

    Steichen, Stephanie; O'Connor, Colleen; Peppas, Nicholas A

    2017-01-01

    Hydrogels based upon terpolymers of methacrylic acid, N-vinyl pyrrolidone, and poly(ethylene glycol) are developed and characterized for their ability to respond to changes in environmental pH and to partition protein therapeutics of varying molecular weights and isoelectric points. P((MAA-co-NVP)-g-EG) hydrogels are synthesized with PEG-based cross-linking agents of varying length and incorporation densities. The composition is confirmed using FT-IR spectroscopy and shows peak shifts indicating hydrogen bonding. Scanning electron microscopy reveals microparticles with an irregular, planar morphology. The pH-responsive behavior of the hydrogels is confirmed under equilibrium and dynamic conditions, with the hydrogel collapsed at acidic pH and swollen at neutral pH. The ability of the hydrogels to partition model protein therapeutics at varying pH and ionic strength is evaluated using three model proteins: insulin, porcine growth hormone, and ovalbumin. Finally, the microparticles are evaluated for adverse interactions with two model intestinal cell lines and show minimal cytotoxicity at concentrations below 5 mg mL -1 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Cobaltoporphyrin-Catalyzed CO 2 /Epoxide Copolymerization: Selectivity Control by Molecular Design

    KAUST Repository

    Anderson, Carly E.; Vagin, Sergei I.; Xia, Wei; Jin, Hanpeng; Rieger, Bernhard

    2012-01-01

    A series of cobalt(III) chloride porphyrin complexes of the general formula 5,10,15,20-tetra(p-alkoxy)phenylporphyrin cobalt chloride (4b-e) and the related 5,10,15,20-tetra(p-nitro)phenylporphyrin cobalt chloride (4f) are presented and their reactivity toward propylene oxide (PO)/CO 2 coupling/copolymerization is explored. While the nitro-substituted complex (4f), in conjunction with an onium salt, shows moderate activity toward cyclization, the 4b-e/onium systems show superior copolymerization activity in comparison to tetraphenylporphyrin Co(III) chloride (4a) with high selectivity and conversion to poly(propylene carbonate) (PPC). A comprehensive copolymerization behavior study of the alkoxy-substituted porphyrin complexes 4b-e in terms of reaction temperature and CO 2 pressure is presented. Complexes bearing longer alkoxy-substituents demonstrate the highest polymerization activity and molecular weights, however all substituted catalyst systems display a reduced tolerance to increased temperature with respect to PPC formation. Studies of the resulting polymer microstructures show excellent head-to-tail epoxide incorporation and near perfectly alternating poly(carbonate) character at lower polymerization temperatures. © 2012 American Chemical Society.

  4. Copolymerization of ε-caprolactone with Epichlorohydrin by a Green Catalyst, Maghnite

    Directory of Open Access Journals (Sweden)

    Abdelghani Bouchama

    2012-06-01

    Full Text Available Most of the cationic initiators used in the synthesis of copolymers are expensive. They may be poisoned by products of the reaction or impurities present in the monomer feed, and contain heavy metals, such as chromium, mercury, antimony, etc., that presents environmental disposal problems for the user. Maghnite is a montmorillonite sheet silicate clay that is exchanged with protons to produce Maghnite-H+ (Mag-H+. This non-toxic and cheaper cationic catalyst was used for the copolymerization of ε-caprolactone (CL with epichlorohydrin (ECH. The effects of the amounts of Mag-H+ and the temperature on the synthesis of poly (ε-caprolactone-co-epichlorohydrin were studied. Increasing Maghnite-H+ proportion and temperature produced the increase in copolymerization yield. The copolymer obtained was characterized by 1H-NMR and IR spectroscopy. Copyright © 2012 BCREC UNDIP. All rights reserved.Received: 24th September 2011, Revised: 12nd December 2011; Accepted: 9th January 2012[How to Cite: A. Bouchama, M.I. Ferrahi, and M. Belbachir. (2012. Copolymerization of ε-caprolactone with Epichlorohydrin by a Green Catalyst, Maghnite. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 43-48.  doi:10.9767/bcrec.7.1.1211.43-48][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1211.43-48 ] | View in 

  5. Radiation-induced copolymerization of methyl trifluoroacrylate with α-olefins

    International Nuclear Information System (INIS)

    Matsuda, O.; Watanabe, T.; Tabata, Y.; Machi, S.

    1978-01-01

    Paper describes the radiation-induced bulk copolymerization of methyl trifluoroacrylate with various α olefins; propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and isobutylene. MTFA (purity above 98%) was synthesized by method described in literature. Reagent grade α-olefins were used. An equimolar mixture of MTFA and α-olefin was charged into the reactor. Trace amounts of oxygen were purged by the freeze-thaw technique. Irradiation was carried out with gamma rays from a 60 Co source under vapor pressure of the monomers at 25 0 C. The product was precipitated and washed with methanol to remove unreacted monomers, and dried under vacuum at 60 0 C. Infrared spectra of the copolymers were measured; compositions were determined from elemental analysis. Reactivity of the α-olefins appears to be related to the electron density at the double bond. All copolymers were found to have almost equimolar compositions and were soluble in polar solvents such as tetrahydrofuran and acetone. Copolymerization was inhibited completely by the addition of 1,1-diphenyl-2-picrihydrazil, but not by water, indicating that the copolymerization proceeds via a radical mechanism. 1 table; 2 figures

  6. Graft copolymerization of glycidyl methacrylate onto delignified kenaf fibers through pre-irradiation technique

    International Nuclear Information System (INIS)

    Sharif, Jamaliah; Mohamad, Siti Fatahiyah; Fatimah Othman, Nor Azilah; Bakaruddin, Nurul Azra; Osman, Hasnul Nizam; Güven, Olgun

    2013-01-01

    Glycidyl methacrylate grafted kenaf (GMA-g-Kenaf) was prepared by pre-irradiation grafting technique. Kenaf fibers were treated with different concentration of sodium chlorite solution before used as trunk polymer. Treated kenaf fibers were irradiated by electron beam followed by grafting reaction in GMA/water emulsion system. The degree of grafting was determined as a function of absorbed dose, reaction time, reaction temperature and concentration of monomer. The results showed that the lignin content was decreased from 14.3% to as low as 3.3% with the increased of sodium chlorite concentration. This was evidenced by SEM pictures which show the surface of treated kenaf fibers was cleaner and smoother compared to that of untreated one. The degree of grafting increased with the increase of absorbed dose, reaction temperature, reaction time and monomer concentration as well as with decreasing lignin content. Formation of graft copolymer was confirmed with SEM, FTIR analysis. The structural investigation by XRD showed that degree of crystallinity of graft copolymers decreased with the increase in degree of grafting. - Highlights: • We used kenaf fibers for radiation induce graft copolymerization with GMA. • Kenaf fibers was treated to remove lignin in order to increase grafting yield. • Treated kenaf fibers were graft copolymerize through preirradiation technique. • Optimum conditions for graft copolymerization of kenaf fibers were established. • Formation of graft copolymer is also confirmed with SEM, FTIR and XRD

  7. Cobaltoporphyrin-Catalyzed CO 2 /Epoxide Copolymerization: Selectivity Control by Molecular Design

    KAUST Repository

    Anderson, Carly E.

    2012-09-11

    A series of cobalt(III) chloride porphyrin complexes of the general formula 5,10,15,20-tetra(p-alkoxy)phenylporphyrin cobalt chloride (4b-e) and the related 5,10,15,20-tetra(p-nitro)phenylporphyrin cobalt chloride (4f) are presented and their reactivity toward propylene oxide (PO)/CO 2 coupling/copolymerization is explored. While the nitro-substituted complex (4f), in conjunction with an onium salt, shows moderate activity toward cyclization, the 4b-e/onium systems show superior copolymerization activity in comparison to tetraphenylporphyrin Co(III) chloride (4a) with high selectivity and conversion to poly(propylene carbonate) (PPC). A comprehensive copolymerization behavior study of the alkoxy-substituted porphyrin complexes 4b-e in terms of reaction temperature and CO 2 pressure is presented. Complexes bearing longer alkoxy-substituents demonstrate the highest polymerization activity and molecular weights, however all substituted catalyst systems display a reduced tolerance to increased temperature with respect to PPC formation. Studies of the resulting polymer microstructures show excellent head-to-tail epoxide incorporation and near perfectly alternating poly(carbonate) character at lower polymerization temperatures. © 2012 American Chemical Society.

  8. Low-cost removal of organic pollutants with nickel nanoparticle loaded ordered macroporous hydrogel as high performance catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingyi, E-mail: tmyi@tjcu.edu.cn [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Huang, Guanbo, E-mail: gbhuang2007@hotmail.com [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Zhang, Sai [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Liu, Yue [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Li, Xianxian [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Wang, Xingrui [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China); Pang, Xiaobo [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Qiu, Haixia, E-mail: qhx@tju.edu.cn [Department of Chemistry, School of Science, Tianjin University, Tianjin 300072 (China)

    2014-06-01

    A facile route for the in situ preparation of catalytically active Ni nanoparticles (NPs) in ordered macroporous hydrogel (OMH) has been developed. The hydrogel was fabricated based on polystyrene colloid template. The electronegativity of amide and carboxyl groups on the poly(acrylamide-co-acryl acid) chains of the hydrogel caused strong binding of Ni{sup 2+} ions which made them distribute uniformly inside the hydrogel. When immersed in NaBH{sub 4} aqueous solution, the Ni{sup 2+} ions on the hydrogel were reduced to Ni NPs. The resultant Ni NPs loaded OMH showed good catalytic activity for the reduction of a common organic pollutant, 4-nitrophenol, with NaBH{sub 4}. A kinetic study of the catalytic reaction was carried out. The rate constant per unit weight could reach 0.53 s{sup −1} g{sup −1}, which is much better than many common hydrogel loaded nickel catalysts. Moreover, the current catalyst can be easily separated and recovered with stable catalytic activity. - Highlights: • A new poly(acrylamide-co-acryl acid) hydrogel with ordered macropores. • A simple in situ fabrication of nickel nanoparticles under mild conditions. • High-performance heterogeneous catalyst for removal of nitrophenol from water. • Good recyclability of catalyst without any complicated regeneration process.

  9. Low-cost removal of organic pollutants with nickel nanoparticle loaded ordered macroporous hydrogel as high performance catalyst

    International Nuclear Information System (INIS)

    Tang, Mingyi; Huang, Guanbo; Zhang, Sai; Liu, Yue; Li, Xianxian; Wang, Xingrui; Pang, Xiaobo; Qiu, Haixia

    2014-01-01

    A facile route for the in situ preparation of catalytically active Ni nanoparticles (NPs) in ordered macroporous hydrogel (OMH) has been developed. The hydrogel was fabricated based on polystyrene colloid template. The electronegativity of amide and carboxyl groups on the poly(acrylamide-co-acryl acid) chains of the hydrogel caused strong binding of Ni 2+ ions which made them distribute uniformly inside the hydrogel. When immersed in NaBH 4 aqueous solution, the Ni 2+ ions on the hydrogel were reduced to Ni NPs. The resultant Ni NPs loaded OMH showed good catalytic activity for the reduction of a common organic pollutant, 4-nitrophenol, with NaBH 4 . A kinetic study of the catalytic reaction was carried out. The rate constant per unit weight could reach 0.53 s −1  g −1 , which is much better than many common hydrogel loaded nickel catalysts. Moreover, the current catalyst can be easily separated and recovered with stable catalytic activity. - Highlights: • A new poly(acrylamide-co-acryl acid) hydrogel with ordered macropores. • A simple in situ fabrication of nickel nanoparticles under mild conditions. • High-performance heterogeneous catalyst for removal of nitrophenol from water. • Good recyclability of catalyst without any complicated regeneration process

  10. Fabrication of keratin-silica hydrogel for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Kakkar, Prachi; Madhan, Balaraman, E-mail: bmadhan76@yahoo.co.in

    2016-09-01

    In the recent past, keratin has been fabricated into different forms of biomaterials like scaffold, gel, sponge, film etc. In lieu of the myriad advantages of the hydrogels for biomedical applications, a keratin-silica hydrogel was fabricated using tetraethyl orthosilicate (TEOS). Textural analysis shed light on the physical properties of the fabricated hydrogel, inturn enabling the optimization of the hydrogel. The optimized keratin-silica hydrogel was found to exhibit instant springiness, optimum hardness, with ease of spreadability. Moreover, the hydrogel showed excellent swelling with highly porous microarchitecture. MTT assay and DAPI staining revealed that keratin-silica hydrogel was biocompatible with fibroblast cells. Collectively, these properties make the fabricated keratin-silica hydrogel, a suitable dressing material for biomedical applications. - Highlights: • Keratin-silica hydrogel has been fabricated using sol–gel technique. • The hydrogel shows appropriate textural properties. • The hydrogel promotes fibroblast cells proliferation. • The hydrogel has potential soft tissue engineering applications like wound healing.

  11. Band gap control using electric field of photonic gel cells fabricated with block copolymer and hydrogel.

    Science.gov (United States)

    Lee, Sung Nam; Baek, Young Bin; Shin, Dong Myung

    2014-08-01

    Optical and electrical characteristics of the devices using photonic gel film and hydrogel electrolyte were studied. Poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) lamellar film with alternating hydrophobic block and hydrophilic polyelectrolyte block polymers (52 kg/mol-b-57 kg/mol) were prepared for the photonic gel. Poly(isobutylene-co-maleic acid) sodium salts were prepared for the hydrogel. This hydrogel fiber is common water swelling material and it owned ions for a device has conductivity. Photonic gel and hydrogel was spin coating onto Indium-tin-oxide (ITO) glass for make electric fields. The reflectance maximum wavelength of photonic crystal device shifted from 538 nm and reached to 557 nm, 585 nm and 604 nm during 30 min voltage applying time. The bandwidth variation was very limited. Loss of electrolyte was much less with hydrogel compared to the pure water. We can control color of hydrogel used photonic device by electric field with reasonable time range under moderate electric field by applying 2 V between two facing electrodes.

  12. pH-responsive self-healing injectable hydrogel based on N-carboxyethyl chitosan for hepatocellular carcinoma therapy.

    Science.gov (United States)

    Qu, Jin; Zhao, Xin; Ma, Peter X; Guo, Baolin

    2017-08-01

    Injectable hydrogels with pH-responsiveness and self-healing ability have great potential for anti-cancer drug delivery. Herein, we developed a series of polysaccharide-based self-healing hydrogels with pH-sensitivity as drug delivery vehicles for hepatocellular carcinoma therapy. The hydrogels were prepared by using N-carboxyethyl chitosan (CEC) synthesized via Michael reaction in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) (PEGDA). Doxorubicin (Dox), as a model of water-soluble small molecule anti-cancer drug was encapsulated into the hydrogel in situ. Self-healing behavior of the hydrogels was investigated at microscopic and macroscopic levels, and the hydrogels showed rapid self-healing performance without any external stimulus owing to the dynamic covalent Schiff-base linkage between amine groups from CEC and benzaldehyde groups from PEGDA. The chemical structures, rheological property, in vitro gel degradation, morphology, gelation time and in vitro Dox release behavior from the hydrogels were characterized. Injectability was verified by in vitro injection and in vivo subcutaneous injection in a rat. pH-responsive behavior was verified by in vitro Dox release from hydrogels in PBS solutions with different pH values. Furthermore, the activity of Dox released from hydrogel matrix was evaluated by employing human hepatocellular liver carcinoma (HepG2). Cytotoxicity test of the hydrogels using L929 cells confirmed their good cytocompatibility. Together, these pH-responsive self-healing injectable hydrogels are excellent candidates as drug delivery vehicles for liver cancer treatment. STATEMENT OF SIGNIFICANCE: pH-responsive drug delivery system could release drug efficiently in targeted acid environment and minimalize the amount of drug release in normal physiological environment. pH-sensitive injectable hydrogels as smart anti-cancer drug delivery carriers show great potential application for cancer therapy. The hydrogels with self

  13. Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

    Directory of Open Access Journals (Sweden)

    Lian S

    2012-09-01

    Full Text Available Sheng Lian,1Yan Xiao,1 Qingqing Bian,1Yu Xia,2 Changfa Guo,2 Shenguo Wang,2 Meidong Lang11Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, People's Republic of China; 2Department of Cardiac Surgery, Zhongshan Hospital, Fudan University and Shanghai Institute of Cardiovascular Diseases, Shanghai, People's Republic of ChinaAbstract: 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(ε-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

  14. Development of honey hydrogel dressing for enhanced wound healing

    International Nuclear Information System (INIS)

    Yusof, Norimah; Ainul Hafiza, A.H.; Zohdi, Rozaini M.; Bakar, Md Zuki A.

    2007-01-01

    Radiation at 25 and 50 kGy showed no effect on the acidic pH of the local honey, Gelam, and its antimicrobial property against Staphylococcus aureus but significantly reduced the viscosity. Honey stored up to 2 years at room temperature retained all the properties studied. Radiation sterilized Gelam honey significantly stimulated the rate of burn wound healing in Sprague-Dawley rats as demonstrated by the increased rate of wound contraction and gross appearance. Gelam honey attenuates wound inflammation; and re-epithelialization was well advanced compared to the treatment using silver sulphadiazine (SSD) cream. To enhance further the use of honey in wound treatment and for easy handling, Gelam honey was incorporated into our hydrogel dressing formulation, which was then cross-linked and sterilized using electron beam at 25 kGy. Hydrogel with 6% of honey was selected based on the physical appearance

  15. Intra-Articular Polyacrylamide Hydrogel Injections Are Not Innocent

    Directory of Open Access Journals (Sweden)

    Murat Tonbul

    2014-01-01

    Full Text Available Osteoarthritis is a chronic disorder characterized by joint cartilage degeneration with concomitant changes in the synovium and subchondral bone metabolism. Many conservative treatment modalities, one of which is intra-articular injections, have been described for the treatment of this disorder. Traditionally, hyaluranic acid and corticosteroids are the agents that have been used for this purpose. Recently, polyacrylamide hydrogels are being used widely. Biocompatibility, nonbioabsorbability, and anti-infectious effect obtained by silver addition made polyacrylamide hydrogels more popular. In this paper, we present a case and the method of our management, in whom host tissue reaction (foreign body granuloma, edema, inflammation, and redness induration has been observed, as the first and unique adverse effect reported in the literature.

  16. A potential bioactive wound dressing based on carboxymethyl cellulose/ZnO impregnated MCM-41 nanocomposite hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Rakhshaei, Rasul [Research Laboratory of Dendrimers and Nanopolymers, Faculty of Chemistry, University of Tabriz, P.O. Box 51666, Tabriz (Iran, Islamic Republic of); Namazi, Hassan, E-mail: namazi@tabrizu.ac.ir [Research Laboratory of Dendrimers and Nanopolymers, Faculty of Chemistry, University of Tabriz, P.O. Box 51666, Tabriz (Iran, Islamic Republic of); Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Science, Tabriz (Iran, Islamic Republic of)

    2017-04-01

    Lack of antibacterial activity, deficient water vapor and oxygen permeability, and insufficient mechanical properties are disadvantages of existing wound dressings. Hydrogels could absorb wound exudates due to their strong swelling ratio and give a cooling sensation and a wet environment. To overcome these shortcomings, flexible nanocomposite hydrogel films was prepared through combination of zinc oxide impregnated mesoporous silica (ZnO-MCM-41) as a nano drug carrier with carboxymethyl cellulose (CMC) hydrogel. Citric acid was used as cross linker to avoid the cytotoxicity of conventional cross linkers. The prepared nanocomposite hydrogel was characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeta potential and UV–vis spectroscopy. Results of swelling and erosion tests showed CMC/ZnO nanocomposite hydrogel disintegrated during the first hours of the test. Using MCM-41 as a substrate for ZnO nanoparticles