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Sample records for carboxymethyl-kappacarrageenan hydrogels crosslinked

  1. New in situ crosslinking chemistries for hydrogelation

    Science.gov (United States)

    Roberts, Meredith Colleen

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

  2. Photochemical Patterning of Ionically Cross-Linked Hydrogels

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    Marion Bruchet

    2013-08-01

    Full Text Available Iron(III cross-linked alginate hydrogel incorporating sodium lactate undergoes photoinduced degradation, thus serving as a biocompatible positive photoresist suitable for photochemical patterning. Alternatively, surface etching of iron(III cross-linked hydrogel contacting lactic acid solution can be used for controlling the thickness of the photochemical pattering. Due to biocompatibility, both of these approaches appear potentially useful for advanced manipulation with cell cultures including growing cells on the surface or entrapping them within the hydrogel.

  3. 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.

  4. Adding Chemical Cross-Links to a Physical Hydrogel

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    Ester Chiessi

    2009-09-01

    Full Text Available Synergistic hydrogels are often encountered in polysaccharide mixtures widely used in food and biopharma products. The xanthan and konjac glucomannan pair provides one of the most studied synergistic hydrogels. Recently we showed that the junction zones stabilizing the 3D structure of this gel are present as macromolecular complexes in solution formed by the partially depolymerised polysaccharidic chains. The non-covalent interactions stabilizing the structure of the polysaccharidic complex cause the melting of the ordered structure of the complex in the solution and of the hydrogels. Introduction of chemical cross-links in the 3D structure of the synergistic hydrogel removes this behaviour, adding new features to the swelling and to the viscoelastic properties of the cured hydrogel. The use of epichlorohydrin as low molecular weight cross-linker does not impact unfavourably on the viability of NIH 3T3 fibroblasts.

  5. Adding chemical cross-links to a physical hydrogel.

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    Paradossi, Gaio; Finelli, Ivana; Cerroni, Barbara; Chiessi, Ester

    2009-01-01

    Synergistic hydrogels are often encountered in polysaccharide mixtures widely used in food and biopharma products. The xanthan and konjac glucomannan pair provides one of the most studied synergistic hydrogels. Recently we showed that the junction zones stabilizing the 3D structure of this gel are present as macromolecular complexes in solution formed by the partially depolymerised polysaccharidic chains. The non-covalent interactions stabilizing the structure of the polysaccharidic complex cause the melting of the ordered structure of the complex in the solution and of the hydrogels. Introduction of chemical cross-links in the 3D structure of the synergistic hydrogel removes this behaviour, adding new features to the swelling and to the viscoelastic properties of the cured hydrogel. The use of epichlorohydrin as low molecular weight cross-linker does not impact unfavourably on the viability of NIH 3T3 fibroblasts. PMID:19783949

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

    Science.gov (United States)

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

    2016-08-01

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

  7. Photopolymerization of cell-encapsulating hydrogels: crosslinking efficiency versus cytotoxicity.

    Science.gov (United States)

    Mironi-Harpaz, Iris; Wang, Dennis Yingquan; Venkatraman, Subbu; Seliktar, Dror

    2012-05-01

    Cell-encapsulating hydrogels used in regenerative medicine are designed to undergo a rapid liquid-to-solid phase transition in the presence of cells and tissues so as to maximize crosslinking and minimize cell toxicity. Light-activated free-radical crosslinking (photopolymerization) is of particular interest in this regard because it can provide rapid reaction rates that result in uniform hydrogel properties with excellent temporal and spatial control features. Among the many initiator systems available for photopolymerization, only a few have been identified as suitable for cell-based hydrogel formation owing to their water solubility, crosslinking properties and non-toxic reaction conditions. In this study, three long-wave ultraviolet (UV) light-activtied photoinitiators (PIs) were comparatively tested in terms of cytotoxicity, crosslinking efficiency and crosslinking kinetics of cell-encapsulating hydrogels. The hydrogels were photopolymerized from poly(ethylene glycol) (PEG) diacrylate or PEG-fibrinogen precursors using Irgacure® PIs I2959, I184 and I651, as well as with a chemical initiator/accelerator (APS/TEMED). The study specifically evaluated the PI type, PI concentration and UV light intensity, and how these affected the mechanical properties of the hydrogel (i.e. maximum storage modulus), the crosslinking reaction times and the reaction's cytotoxicity to encapsulated cells. Only two initiators (I2959 and I184) were identified as being suitable for achieving both high cell viability and efficient crosslinking of the cell-encapsulating hydrogels during the photopolymerization reaction. Optimization of PI concentration or irradiation intensity was particularly important for achieving maximum mechanical properties; a sub-optimal choice of PI concentration or irradiation intensity resulted in a substantial reduction in hydrogel modulus. Cytocompatibility may be compromised by unnecessarily prolonging exposure to cytotoxic free radicals or inadvertently

  8. 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

  9. Ionically cross-linked alginate hydrogels as tissue engineering scaffolds

    Science.gov (United States)

    Kuo, Catherine Kyleen

    Generation of living tissues through tissue engineering can be achieved via incorporation of cells into synthetic scaffolds designed to facilitate new tissue formation. Necessary characteristics of a scaffold include biocompatibility, high porosity with controllable pore size and interconnectivity, moldability, chemical and mechanical stability, and structural homogeneity. Hydrogels often possess many of the necessary characteristics and thus are favorable candidates for scaffolding. Alginate hydrogels are commonly made by ionically crosslinking with calcium ions from CaCl2 or CaSO4. These hydrogels are favored for their mild gel formation, however the gelation rate is rapid and uncontrollable (fast-gelation), resulting in varying crosslinking density throughout the gel. In this work, structurally homogeneous calcium alginate hydrogels were formed via a slow-gelation system that utilizes uniform mixing of CaCO3 with sodium alginate solution, and the addition of slowly hydrolyzing D-gluconic acid lactone to slowly release calcium ions for crosslinking. Homogeneity and mechanical properties of these hydrogels were shown to be superior to those of fast-gelled hydrogels. Gelation rate was controlled through the incorporation of CaSO4, and by varying total calcium content, polymer concentration and gelation temperature. Control over mechanical properties and diffusivity was demonstrated in the homogeneous hydrogels by adjusting compositional variables. Consistent control over solute diffusivity through gel discs reflected the structural homogeneity of the gels. To overcome the instability of ionically crosslinked gels in tissue culture medium, a method was developed to control the hydrogel dimensions by adjusting the ionic concentration of the medium. Stability of the hydrogels in this controlled environment was characterized through swelling experiments and mechanical testing. To provide for scaffold degradation and thereby promote tissue growth, alginate lyase was

  10. Molecular mechanisms in deformation of cross-linked hydrogel nanocomposite.

    Science.gov (United States)

    Mathesan, Santhosh; Rath, Amrita; Ghosh, Pijush

    2016-02-01

    The self-folding behavior in response to external stimuli observed in hydrogels is potentially used in biomedical applications. However, the use of hydrogels is limited because of its reduced mechanical properties. These properties are enhanced when the hydrogels are cross-linked and reinforced with nanoparticles. In this work, molecular dynamics (MD) simulation is applied to perform uniaxial tension and pull out tests to understand the mechanism contributing towards the enhanced mechanical properties. Also, nanomechanical characterization is performed using quasi static nanoindentation experiments to determine the Young's modulus of hydrogels in the presence of nanoparticles. The stress-strain responses for chitosan (CS), chitosan reinforced with hydroxyapatite (HAP) and cross-linked chitosan are obtained from uniaxial tension test. It is observed that the Young's modulus and maximum stress increase as the HAP content increases and also with cross-linking process. Load displacement plot from pullout test is compared for uncross-linked and cross-linked chitosan chains on hydroxyapatite surface. MD simulation reveals that the variation in the dihedral conformation of chitosan chains and the evolution of internal structural variables are associated with mechanical properties. Additional results reveal that the formation of hydrogen bonds and electrostatic interactions is responsible for the above variations in different systems. PMID:26652360

  11. Chemically cross-linked silk fibroin hydrogel with enhanced elastic properties, biodegradability, and biocompatibility

    OpenAIRE

    Park, Won Ho

    2016-01-01

    Min Hee Kim, Won Ho Park Department of Advanced Organic Materials and Textile Engineering System, Chungnam National University, Daejeon, Korea Abstract: In this study, the synthesis of silk fibroin (SF) hydrogel via chemical cross-linking reactions of SF due to gamma-ray (γ-ray) irradiation was investigated, as were the resultant hydrogel’s properties. Two different hydrogels were investigated: physically cross-linked SF hydrogel and chemically cross-linked SF hydrogel i...

  12. Preparation and Properties of Non-Crosslinked and Ionically Crosslinked Chitosan/Agar Blended Hydrogel Films

    OpenAIRE

    Mahmoud Nasef, Mohamed; Esam A. El-hefian; Saalah, Sariah; Yahaya, Adul Hamid

    2011-01-01

    Hydrogel films of chitosan (Cs) and agar blends of various proportions were prepared using physical solution blending. Some of the obtained films were ionically cross-linked by treatment with calcium chloride solution. The obtained films were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry analysis (TGA), differential scanning calorimetery (DSC) and universal mechanical tester. The non-crosslinked Cs/agar blended films showed lower water swelling, melting tem...

  13. [Study on synthesis of physically crosslinked biomedical polyurethane hydrogel].

    Science.gov (United States)

    Yin, Zhengyan; Niu, Hong; Tan, Hong; Xie, Xingyi; Zhong, Yinping

    2006-06-01

    In this study, using ethylene carbonate and ethanolamine, we synthesized a novel diol chain-extender, bis-hydroxylethyl carbomate (EC-AE), which contains carbomate structure. The polyurethanes, PUA25 and PUB25, with different extenders, EC-AE and BDO, were synthesized by one-step polymerization, respectively. Their structures were characterized by using FT-IR and DSC. The results indicated that the microphase separation degree of PUA25 was less than that of PUB25, in other words, the amount of hydrogen bonding between hard segments and soft segments in PUA25 was superior to that in PUB25. And the formation of physically crosslinked hydrogels prepared by PUA25 and PUB25 were studied in detail. It was found that only PUA25 can form hydrogel in situ from solution state by cooling. And this kind of hydrogels showed the transition cycle of "gel-sol-gel" under "cooling-heating-cooling" thermal cycles, respectively. The results suggested that the physically crosslinked polyurethane hydrogels were easily possessed in high degree of phase mixing. PMID:16856394

  14. Tailoring Hydrogel Viscoelasticity with Physical and Chemical Crosslinking

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    Michal Bartnikowski

    2015-12-01

    Full Text Available Biological tissues are viscoelastic, demonstrating a mixture of fluid and solid responses to mechanical strain. Whilst viscoelasticity is critical for native tissue function, it is rarely used as a design criterion in biomaterials science or tissue engineering. We propose that viscoelasticity may be tailored to specific levels through manipulation of the hydrogel type, or more specifically the proportion of physical and chemical crosslinks present in a construct. This theory was assessed by comparing the mechanical properties of various hydrogel blends, comprising elastic, equilibrium, storage and loss moduli, as well as the loss tangent. These properties were also assessed in human articular cartilage explants. It was found that whilst very low in elastic modulus, the physical crosslinks found in gellan gum-only provided the closest approximation of loss tangent levels found in cartilage. Blends of physical and chemical crosslinks (gelatin methacrylamide (GelMA combined with gellan gum gave highest values for elastic response. However, a greater proportion of gellan gum to GelMA than investigated may be required to achieve native cartilage viscoelasticity in this case. Human articular chondrocytes encapsulated in hydrogels remained viable over one week of culture. Overall, it was shown that viscoelasticity may be tailored similarly to other mechanical properties and may prove a new criterion to be included in the design of biomaterial structures for tissue engineering.

  15. E-beam crosslinked, biocompatible functional hydrogels incorporating polyaniline nanoparticles

    International Nuclear Information System (INIS)

    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.

  16. Tumor bioengineering using a transglutaminase crosslinked hydrogel.

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    Josephine Y Fang

    Full Text Available Development of a physiologically relevant 3D model system for cancer research and drug development is a current challenge. We have adopted a 3D culture system based on a transglutaminase-crosslinked gelatin gel (Col-Tgel to mimic the tumor 3D microenvironment. The system has several unique advantages over other alternatives including presenting cell-matrix interaction sites from collagen-derived peptides, geometry-initiated multicellular tumor spheroids, and metabolic gradients in the tumor microenvironment. Also it provides a controllable wide spectrum of gel stiffness for mechanical signals, and technical compatibility with imaging based screening due to its transparent properties. In addition, the Col-Tgel provides a cure-in-situ delivery vehicle for tumor xenograft formation in animals enhancing tumor cell uptake rate. Overall, this distinctive 3D system could offer a platform to more accurately mimic in vivo situations to study tumor formation and progression both in vitro and in vivo.

  17. Water diffusion into radiation crosslinked PVA-PVP network hydrogels

    International Nuclear Information System (INIS)

    A series of hydrogels comprised of crosslinked networks of poly(vinyl alcohol), PVA and poly(vinyl pyrrolidone), PVP, have been prepared using gamma radiolysis of aqueous solutions of the polymers to effect crosslinking of the polymer chains. The molecular weight of the PVA was in the range 75-105 kDa and of PVP was 360 kDa. Gel doses were measured for the polymers and found to be 11 kGy for PVA, 3.7 kGy for PVP and 4.6 kGy for a mixture of PVA and PVP with a mole fraction of PVP of 0.19. The initial water content of the gels was 87.2 wt%. Further water uptake studies were undertaken using both gravimetric and NMR imaging analyses. These studies showed that the uptake processes followed Fickian kinetics with diffusion coefficients ranging from 1.8x10-11 for the PVA hydrogel to 4.4x10-11 m2 s-1 for the PVP hydrogel for radiation doses of 25 kGy and a temperature of 310 K. At 298 K the gravimetric study yielded a diffusion coefficient of 1.5x10-11 m2 s-1 whereas the NMR analysis yielded a slightly higher value of 2.0x10-11 m2 s-1 for the hydrogel with a mole fraction of PVP of 0.19 and a radiation dose of 25 kGy.

  18. Experimental design of mixture applied to study PVP hydrogels properties crosslinked by ionizing radiation

    International Nuclear Information System (INIS)

    Hydrogels are three dimensional hydrophilic crosslinked polymeric networks that have capacity to swell by absorbing water or biological fluids without dissolve. Hydrogels have been widely used in different application fields from agriculture, industry and in biomedicine. The properties of a hydrogel are extremely important in selecting which materials are suitable for a specific application. So mixtures can offer hydrogels with different properties to different applications. The PVP hydrogels were prepared by gamma radiation of an aqueous polymer solution and crosslinked by gamma ray, an effective and simple method for hydrogel formation that offers some advantages over the other techniques. In this work, a mixture experimental design was used to study the relationship between polymer cross-linking and swelling properties of PVP hydrogels with PEG as plasticizer and agar as gellifier. The gel fraction was measured for every mixture specified for the experiment D-optimal designs. (author)

  19. Rheological Characterization of Cataplasm Bases Composed of Cross-Linked Partially Neutralized Polyacrylate Hydrogel

    OpenAIRE

    Wang, Jian; Zhang, Hongqin; An, Dianyun; Yu, Jian; Li, Wei; Shen, Teng; Wang, Jianxin

    2014-01-01

    Viscoelasticity is a useful parameter for characterizing the intrinsic properties of the cross-linked polyacrylate hydrogel used in cataplasm bases. The aim of this study was to investigate the effects of various formulation parameters on the rheological characteristics of polyacrylate hydrogel. The hydrogel layers were formed using a partially neutralized polyacrylate (Viscomate™), which contained acrylic acid and sodium acrylate in different copolymerization ratios, as the cross-linked gel ...

  20. Chemically cross-linked silk fibroin hydrogel with enhanced elastic properties, biodegradability, and biocompatibility

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    Kim MH

    2016-06-01

    Full Text Available Min Hee Kim, Won Ho Park Department of Advanced Organic Materials and Textile Engineering System, Chungnam National University, Daejeon, Korea Abstract: In this study, the synthesis of silk fibroin (SF hydrogel via chemical cross-linking reactions of SF due to gamma-ray (γ-ray irradiation was investigated, as were the resultant hydrogel’s properties. Two different hydrogels were investigated: physically cross-linked SF hydrogel and chemically cross-linked SF hydrogel irradiated at different doses of γ-rays. The effects of the irradiation dose and SF concentration on the hydrogelation of SF were examined. The chemically cross-linked SF hydrogel was compared with the physically cross-linked one with regard to secondary structure and gel strength. Furthermore, the swelling behavior, crystallinity, and biodegradation of the SF hydrogels were characterized. To assay cell proliferation, the cell viability of human mesenchymal stem cells on the lyophilized SF hydrogel scaffolds was evaluated, and no significant cytotoxicity against human mesenchymal stem cells was observed. Keywords: silk fibroin, hydrogels, biodegradation rate, gamma irradiation, cross-linking

  1. Radiation crosslinking of starch/water-soluble polymer blends for hydrogel

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    Hashim, K.; Mohid, N.; Bahari, K.; Dahlan, K.Z. [Radiation Processing Technology Division, Malaysian Institute Nuclear Technology Research Malaysia (MINT), Bangi, 43000 Kajang (Malaysia)

    2000-03-01

    Water-soluble polymers such as PVP(polyvinyl pyrrolidone) and PVA(polyvinyl alcohol), in aqueous solution can form hydrogel easily upon gamma or electron beam irradiation. The properties of hydrogels, particularly for wound dressing application, can be further improved by adding sago starch to the blend. Results show improved gel strength and elongation properties of the hydrogel with increasing sago concentration. It was found that the PVA/sago hydrogel gives better gel strength and elongation than the PVP/sago hydrogel. The tackiness property of the PVA/sago hydrogel increased with increase amount of sago starch added. In case of PVP/sago hydrogel, the tackiness property shows significant increase with increasing amount of sago except for the 5%PVP composition. The swelling properties of PVP/sago and PVA/sago hydrogel decreased with increasing amount of sago but the crosslink density of the hydrogels also reduced. (author)

  2. Radiation crosslinking of starch/water-soluble polymer blends for hydrogel

    International Nuclear Information System (INIS)

    Water-soluble polymers such as PVP(polyvinyl pyrrolidone) and PVA(polyvinyl alcohol), in aqueous solution can form hydrogel easily upon gamma or electron beam irradiation. The properties of hydrogels, particularly for wound dressing application, can be further improved by adding sago starch to the blend. Results show improved gel strength and elongation properties of the hydrogel with increasing sago concentration. It was found that the PVA/sago hydrogel gives better gel strength and elongation than the PVP/sago hydrogel. The tackiness property of the PVA/sago hydrogel increased with increase amount of sago starch added. In case of PVP/sago hydrogel, the tackiness property shows significant increase with increasing amount of sago except for the 5%PVP composition. The swelling properties of PVP/sago and PVA/sago hydrogel decreased with increasing amount of sago but the crosslink density of the hydrogels also reduced. (author)

  3. Evaluation of fibroblasts adhesion and proliferation on alginate-gelatin crosslinked hydrogel.

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    Bapi Sarker

    Full Text Available Due to the relatively poor cell-material interaction of alginate hydrogel, alginate-gelatin crosslinked (ADA-GEL hydrogel was synthesized through covalent crosslinking of alginate di-aldehyde (ADA with gelatin that supported cell attachment, spreading and proliferation. This study highlights the evaluation of the physico-chemical properties of synthesized ADA-GEL hydrogels of different compositions compared to alginate in the form of films. Moreover, in vitro cell-material interaction on ADA-GEL hydrogels of different compositions compared to alginate was investigated by using normal human dermal fibroblasts. Viability, attachment, spreading and proliferation of fibroblasts were significantly increased on ADA-GEL hydrogels compared to alginate. Moreover, in vitro cytocompatibility of ADA-GEL hydrogels was found to be increased with increasing gelatin content. These findings indicate that ADA-GEL hydrogel is a promising material for the biomedical applications in tissue-engineering and regeneration.

  4. Synthesis and Characterization of Dendron Cross-linked PEG Hydrogels as Corneal Adhesives

    OpenAIRE

    Oelker, Abigail M.; Berlin, Jason A.; Wathier, Michel; Grinstaff, Mark W.

    2011-01-01

    In pursuit of a wound-specific corneal adhesive, hydrogels formed by the reaction of propionaldehyde, butyraldehyde, or 2-oxoethyl succinate-functionalized poly(ethylene glycol) (PEG) with a peptide-based dendritic cross-linker (Lys3Cys4) were characterized. These macromers react within minutes of mixing to form transparent and elastic hydrogels with in vitro degradation times that range from hours to months based on the type of bonds formed during the cross-linking reaction – either thiazoli...

  5. The effects of PEG hydrogel crosslinking density on protein diffusion and encapsulated islet survival and function

    OpenAIRE

    Weber, Laney M.; Lopez, Christina G.; Anseth, Kristi S.

    2009-01-01

    The rational design of immunoprotective hydrogel barriers for transplanting insulin-producing cells requires an understanding of protein diffusion within the hydrogel network and how alterations to the network structure affect protein diffusion. Hydrogels of varying crosslinking density were formed via the chain polymerization of dimethacrylated PEG macromers of varying molecular weight, and the diffusion of six model proteins with molecular weights ranging from 5,700 to 67,000 g/mol was obse...

  6. Influence of radiation crosslinked carboxymethyl-chitosan/gelatin hydrogel on cutaneous wound healing

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xin [Beijing Key Laboratory for Solid Waste Utilization and Management, College of Engineering, Peking University, Beijing 100871 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Burns, Beijing Jishuitan Hospital, Beijing 100035 (China); Zhang, Yaqing; Zhang, Xiangmei [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Xu, Ling, E-mail: lingxu@pku.edu.cn [Beijing Key Laboratory for Solid Waste Utilization and Management, College of Engineering, Peking University, Beijing 100871 (China); Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Shenzhen Key Laboratory for Polymer Science, Peking University Shenzhen Institute, Shenzhen 518057 (China); Chen, Xin, E-mail: xchin@vip.sina.com [Department of Burns, Beijing Jishuitan Hospital, Beijing 100035 (China); Wei, Shicheng [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Peking University, Beijing 100081 (China)

    2013-12-01

    A series of carboxymethyl chitosan (CM-chitosan) and gelatin hydrogels were prepared by radiation crosslinking. A pre-clinical study was performed by implantation model and full-thickness cutaneous wound model in Sprague–Dawley rats to preliminarily evaluate the biocompatibility, biodegradability and effects on healing. In the implantation test, as a component of the hydrogels, CM-chitosan showed a positive effect on promoting cell proliferation and neovascularization, while gelatin was efficient to stabilize the structure and prolong the degradation time. To evaluate the function on wound healing, the hydrogels were applied to the relatively large full-thickness cutaneous wounds (Φ3.0 cm). Compared with the control groups, the hydrogel group showed significantly higher percentage of wound closure on days 9, 12 and 15 postoperatively, which was consistent with the significantly thicker granulation tissue on days 3 and 6. All results apparently revealed that the radiation crosslinked CM-chitosan/Gelatin hydrogels could induce granulation tissue formation and accelerate the wound healing. - Highlights: • The hydrogels were prepared by a facile and green method, radiation crosslinking. • The biodegradability and mechanical strength can be regulated by composition. • The hydrogels promote fibroblasts proliferation and neovascularization. • The hydrogels lead to earlier tissue granulation and re-epithelialization. • The hydrogels are ideal wound healing materials with excellent biocompatibility.

  7. Influence of radiation crosslinked carboxymethyl-chitosan/gelatin hydrogel on cutaneous wound healing

    International Nuclear Information System (INIS)

    A series of carboxymethyl chitosan (CM-chitosan) and gelatin hydrogels were prepared by radiation crosslinking. A pre-clinical study was performed by implantation model and full-thickness cutaneous wound model in Sprague–Dawley rats to preliminarily evaluate the biocompatibility, biodegradability and effects on healing. In the implantation test, as a component of the hydrogels, CM-chitosan showed a positive effect on promoting cell proliferation and neovascularization, while gelatin was efficient to stabilize the structure and prolong the degradation time. To evaluate the function on wound healing, the hydrogels were applied to the relatively large full-thickness cutaneous wounds (Φ3.0 cm). Compared with the control groups, the hydrogel group showed significantly higher percentage of wound closure on days 9, 12 and 15 postoperatively, which was consistent with the significantly thicker granulation tissue on days 3 and 6. All results apparently revealed that the radiation crosslinked CM-chitosan/Gelatin hydrogels could induce granulation tissue formation and accelerate the wound healing. - Highlights: • The hydrogels were prepared by a facile and green method, radiation crosslinking. • The biodegradability and mechanical strength can be regulated by composition. • The hydrogels promote fibroblasts proliferation and neovascularization. • The hydrogels lead to earlier tissue granulation and re-epithelialization. • The hydrogels are ideal wound healing materials with excellent biocompatibility

  8. Improvement of poly(vinyl alcohol)/poly(vinyl pyrrolidone) blended hydrogel by radiation crosslinking

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A series of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) blended hydrogel with kappa-carrageenan (KC) were prepared by radiation crosslinking with electron beam to improve the properties of hydrogel as wound dressing. The properties of the blended hydrogels were evaluated in terms of gel fraction, swelling behavior, gel strength and water evaporation from hydrogel. Gel fraction of PVA/PVP was saturated at 50 kGy and the achieved gel fraction was 70%~80%. However, obtained hydrogel was very fragile and produced many bubbles at a dose of 50kGy and above, hence 1%~5% KC were added to give toughness. The rate of gel formation and the toughness of the blended hydrogel were raised after mixing KC. The PVA/PVP/KC blended hydrogel irradiated showed satisfactory properties for wound dressing, it did not produce bubble during irradiation, and it could retard the water evaporation.

  9. The influence of hyaluronic acid hydrogel crosslinking density and macromolecular diffusivity on human MSC chondrogenesis and hypertrophy

    OpenAIRE

    Bian, Liming; Hou, Chieh; Tous, Elena; Rai, Reena; Mauck, Robert L.; Burdick, Jason A.

    2012-01-01

    Hyaluronic acid (HA) hydrogels formed via photocrosslinking provide stable 3D hydrogel environments that support the chondrogenesis of mesenchymal stem cells (MSCs). Crosslinking density has a significant impact on the physical properties of hydrogels, including their mechanical stiffness and macromolecular diffusivity. Variations in the HA hydrogel crosslinking density can be obtained by either changes in the HA macromer concentration (1, 3, or 5% w/v at 15 min exposure) or the extent of rea...

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

    Science.gov (United States)

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

    2016-07-01

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

  11. Study of the effect of mixing approach on cross-linking efficiency of hyaluronic acid-based hydrogel cross-linked with 1,4-butanediol diglycidyl ether.

    Science.gov (United States)

    Al-Sibani, Mohammed; Al-Harrasi, Ahmed; Neubert, Reinhard H H

    2016-08-25

    Regardless of various strategies reported for cross-linking hyaluronic acid (HA) with 1,4-butanediol diglycidyl ether (BDDE), seeking new strategies that enhance cross-linking efficiency with a low level of cross-linker is essential. In this work, we studied the influence of mixing approach on two cross-linked BDDE-HA hydrogels prepared by two different mixing approaches; the large-batch mixing approach in which the hydrogel quantities were all mixed as a single lump in one container (hydrogel 1), and the small-batches mixing approach in which the hydrogel quantities were divided into smaller batches, mixed separately at various HA/BDDE ratios then combined in one reaction mixture (hydrogel 2). The result showed that the cross-linking reaction was mixing process-dependent. Degradation tests proved that, in relation to hydrogel 1, hydrogel 2 was more stable, and exhibited a higher resistance towards hyaluronidase activity. The swelling ratio of hydrogel 1 was significantly higher than that of hydrogel 2 in distilled water; however, in phosphate buffer saline, both hydrogels showed no significant difference. SEM images demonstrated that hydrogel 2 composite showed a denser network structure and smaller pore-size than hydrogel 1. In comparison to native HA, the occurrence of chemical modification in the cross-linked hydrogels was confirmed by FTIR and NMR distinctive peaks. These peaks also provided evidence that hydrogel 2 exhibited a higher degree of modification than hydrogel 1. In conclusion, the small-batches mixing approach proved to be more effective than large-batch mixing in promoting HA-HA entanglement and increasing the probability of BDDE molecules for binding with HA chains. PMID:27312477

  12. An Injectable Enzymatically Crosslinked Carboxymethylated Pullulan/Chondroitin Sulfate Hydrogel for Cartilage Tissue Engineering

    Science.gov (United States)

    Chen, Feng; Yu, Songrui; Liu, Bing; Ni, Yunzhou; Yu, Chunyang; Su, Yue; Zhu, Xinyuan; Yu, Xiaowei; Zhou, Yongfeng; Yan, Deyue

    2016-01-01

    In this study, an enzymatically cross-linked injectable and biodegradable hydrogel system comprising carboxymethyl pullulan-tyramine (CMP-TA) and chondroitin sulfate-tyramine (CS-TA) conjugates was successfully developed under physiological conditions in the presence of both horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) for cartilage tissue engineering (CTTE). The HRP crosslinking method makes this injectable system feasible, minimally invasive and easily translatable for regenerative medicine applications. The physicochemical properties of the mechanically stable hydrogel system can be modulated by varying the weight ratio and concentration of polymer as well as the concentrations of crosslinking reagents. Additionally, the cellular behaviour of porcine auricular chondrocytes encapsulated into CMP-TA/CS-TA hydrogels demonstrates that the hydrogel system has a good cyto-compatibility. Specifically, compared to the CMP-TA hydrogel, these CMP-TA/CS-TA composite hydrogels have enhanced cell proliferation and increased cartilaginous ECM deposition, which significantly facilitate chondrogenesis. Furthermore, histological analysis indicates that the hydrogel system exhibits acceptable tissue compatibility by using a mouse subcutaneous implantation model. Overall, the novel injectable pullulan/chondroitin sulfate composite hydrogels presented here are expected to be useful biomaterial scaffold for regenerating cartilage tissue.

  13. Carboxymethyl-κcarrageenan hydrogels crosslinked by gamma radiation for various potential applications

    International Nuclear Information System (INIS)

    Carboxymethylated polysaccharides such as carboxymethylcellulose, carboxymethylstarch and carboxymethylchitosan were found to predominantly undergo crosslinking reactions when irradiated as highly concentrated aqueous solution. κ-Carrageenan (κC) is a sulfated anionic polysaccharide capable of forming thermoreversible gels. However, it typically undergoes depolymerization when exposed to high-energy radiation. The main objective of this study is to use carboxymethyl-κ-Carrageenan to prepare on of crosslinked hydrogels using gamma radiation for various potential applications. Carboxymethyl-κ-Carrageenan samples with varying degree of substitution (DS) were synthesized employing multi-step carboxymethylation. Carboxymethylation was carried out in 80% aqueous isopropyl alcohol medium, activated with appropriate amount of 40% sodium hydroxide and reacted with monochloroacetic acid (MCA) as ethrifying agent. Chemical and structural properties of the derivatives were determined. For preparation of hydrogels and crosslinking experiments, concentrated aqueous solutions of CMκC were prepared using a hybrid mixer to obgtain 10-40% (w/w) in paste-form. Gamma radiation was conducted in 60Co QuBs facility (Japan) at doses 0-100 kGy. Hydrogels were characterized in terms of gel content and swelling behavior in different aqueous media. The radiation crosslinking of carboxymethyl-κ-carrageenan was successfully achieved. Crosslinked hydrogels showed dependence on DS, concentration and radiation dose. Highest gel content was above 73% exhibited by 40% CMκC3s-based hydrogels (DS 1.66) irradiated between 50-100 kGy. The hydrogels exhibited different degrees of swelling in different aqueous media. The initial evaluation of the hydrogels as wound dressing and metal adsorbent proved to be promising. Crosslinked CMκC hydrogels were also found to be biodegradable thus making it an environment friendly material. (author)

  14. 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.

  15. 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. PMID:27230478

  16. Synthesis and Characterization of Crosslinked Hydrogel Polyacrylamide (PAAM)-Co-Alginate Prepared by Gama Irradiation

    International Nuclear Information System (INIS)

    Crosslinked poly(acrylamide) (PAAM)-co-alginate hydrogels were prepared by gamma irradiation (γ-irradiation) and their conditions such as irradiation dose and alginate concentration were studied. PAAM-co-alginate was crosslinked to yield water sorption materials with various ability to absorb water (swelling) depending on the preparation conditions (e.g. γ-irradiation dosage>20 kGy) and alginate concentration (0.5 - 1 wt %). With an increase of γ-irradiation dosage and alginate concentration, the gels content and water absorption were increasing markedly. The swelling properties of hydrogel in urea and NaCl solution and the effect of temperature were also investigated. Intensity decreasing of functional goups of OH and NH2 in the IR spectrum indicated that IPN (Interpenetreting Network) structure occured in the network of hydrogels. The ability of hydrogel to absorp and retain a large amount of water suggested their possible uses in health care and agriculture. (author)

  17. Crosslinked hydrogels based on biological macromolecules with potential use in skin tissue engineering.

    Science.gov (United States)

    Vulpe, Raluca; Popa, Marcel; Picton, Luc; Balan, Vera; Dulong, Virginie; Butnaru, Maria; Verestiuc, Liliana

    2016-03-01

    Zero-length crosslinked hydrogels have been synthesized by covalent linking of three natural polymers (collagen, hyaluronic acid and sericin), in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. The hydrogels have been investigated by FT-IR spectroscopy, microcalorimetry, in vitro swelling, enzymatic degradation, and in vitro cell viability studies. The obtained crosslinked hydrogels showed a macroporous structure, high swelling degree and in vitro enzymatic resistance compared to uncrosslinked collagen. The in vitro cell viability studies performed on normal human dermal fibroblasts assessed the sericin proliferation properties indicating a potential use of the hydrogels based on collagen, hyaluronic acid and sericin in skin tissue engineering. PMID:26704998

  18. Effect of Crosslinking Agent Concentration on the Properties of Unmedicated Hydrogels

    Directory of Open Access Journals (Sweden)

    Rachel Shet Hui Wong

    2015-09-01

    Full Text Available Novel polyethylene oxide (PEO hydrogel films were synthesized via UV crosslinking with varying concentrations of pentaerythritol tetra-acrylate (PETRA as crosslinking agent. The aim was to study the effects of the crosslinking agent on the material properties of hydrogel films intended for dermatological applications. Fabricated film samples were characterized using swelling studies, scanning electron microscopy, tensile testing and rheometry. Films showed rapid swelling and high elasticity. The increase of PETRA concentration resulted in significant increase in the gel fraction and crosslinking density (ρc, while causing a significant decrease in the equilibrium water content (EWC, average molecular weight between crosslinks (\\({\\overline{M}}_{c}\\, and mesh size (ζ of films. From the scanning electron microscopy, cross-linked PEO hydrogel network appeared as cross-linked mesh-like structure with interconnected micropores. Rheological studies showed PEO films required a minimum of 2.5% w/w PETRA to form stable viscoelastic solid gels. Preliminary studies concluded that a minimum of 2.5% w/w PETRA is required to yield films with desirable properties for skin application.

  19. External stimuli response on a novel chitosan hydrogel crosslinked with formaldehyde

    Indian Academy of Sciences (India)

    A Singh; S S Narvi; P K Dutta; N D Pandey

    2006-06-01

    Keeping in mind the significance of hydrogels as an external stimuli sensitive super absorbing material, some transparent covalent hydrogels of chitosan were prepared by crosslinking with varying amounts of formaldehyde solution used as crosslinking agent. The characteristics of hydrogels were investigated by Fourier transform infrared (FT–IR) spectroscopy and swelling experiments. The effect of crosslinking agent on water absorbency has been investigated. The hydrogels exhibited a relatively higher swelling ratio in the range of 2066–3306% and equilibrium water content (EWC) in the range of 95.38–97.06% at pH 7 and 35°C temperature. The influence of external stimuli such as pH, temperature, and ionic strength of the swelling media on equilibrium swelling properties has been observed. Hydrogels showed a typical pH and temperature responsive behaviour such as low pH and high temperature has maximum swelling while high pH and low temperature show minimum swelling. An increase in the ionic strength of swelling media caused a continuous decrease in the swelling of hydrogels at both acidic and basic pH.

  20. Thiol-ene crosslinking polyamidoamine dendrimer-hyaluronic acid hydrogel system for biomedical applications.

    Science.gov (United States)

    Bi, Xiangdong; Liang, Aiye; Tan, Yu; Maturavongsadit, Panita; Higginbothem, Ashley; Gado, Togor; Gramling, Abigail; Bahn, Hanna; Wang, Qian

    2016-06-01

    A series of alkene functionalized polyamidoamine (PAMAM) dendrimers were synthesized to prepare in situ forming hydrogels with varied gelation time and mechanical properties through crosslinking with thiolated hyaluronic acid (HS-HA). By varying the alkenyl groups on the dendrimers, the gelation time displayed a large range from 8 seconds to 18 hours, and the modulus of the hydrogels ranged from 36 to 183 Pa under experimental conditions. Investigation by (1)H-NMR spectroscopy revealed that the gelation time and the stiffness of the hydrogels were governed by the degree of electron deficiency of alkenyl groups on the dendrimers. This research provided a systematic study on the relationship between chemical structures versus gelation time and mechanical properties of hydrogels, which could guide the way to synthesize in situ forming hydrogels with designated gelation time and stiffness for biomedical applications. Further, a RGD peptide was attached to the PAMAM dendrimers to enhance cell attachment and proliferation. Viability assays of Human Umbilical Vein Endothelial Cells (HUVEC) in the synthesized hydrogels demonstrated the biocompatibility of the hydrogels after 48 hours of culturing, and the RGD peptide improved the viability of HUVEC cells in hydrogels. We believe the PAMAM/HA hydrogel system is a tuneable and biocompatible system for diverse biomedical applications. PMID:26923639

  1. Physical Cross-Linking Starch-Based Zwitterionic Hydrogel Exhibiting Excellent Biocompatibility, Protein Resistance, and Biodegradability.

    Science.gov (United States)

    Ye, Lei; Zhang, Yabin; Wang, Qiangsong; Zhou, Xin; Yang, Boguang; Ji, Feng; Dong, Dianyu; Gao, Lina; Cui, Yuanlu; Yao, Fanglian

    2016-06-22

    In this work, a novel starch-based zwitterionic copolymer, starch-graft-poly(sulfobetaine methacrylate) (ST-g-PSBMA), was synthesized via Atom Transfer Radical Polymerization. Starch, which formed the main chain, can be degraded completely in vivo, and the pendent segments of PSBMA endowed the copolymer with excellent protein resistance properties. This ST-g-PSBMA copolymer could self-assemble into a physical hydrogel in normal saline, and studies of the formation mechanism indicated that the generation of the physical hydrogel was driven by electrostatic interactions between PSBMA segments. The obtained hydrogels were subjected to detailed analysis by scanning electron microscopy, swelling ratio, protein resistance, and rheology tests. Toxicity and hemolysis analysis demonstrated that the ST-g-PSBMA hydrogels possess excellent biocompatibility and hemocompatibility. Moreover, the cytokine secretion assays (IL-6, TNF-α, and NO) confirmed that ST-g-PSBMA hydrogels had low potential to trigger the activation of macrophages and were suitable for in vivo biomedical applications. On the basis of these in vitro results, the ST-g-PSBMA hydrogels were implanted in SD rats. The tissue responses to hydrogel implantation and the hydrogel degradation in vivo were determined by histological analysis (Hematoxylin and eosin, Van Gieson, and Masson's Trichrome stains). The results presented in this study demonstrate that the physical cross-linking, starch-based zwitterionic hydrogels possess excellent protein resistance, low macrophage-activation properties, and good biocompatibility, and they are a promising candidate for an in vivo biomedical application platform. PMID:27249052

  2. Novel crosslinked alginate/hyaluronic acid hydrogels for nerve tissue engineering

    Science.gov (United States)

    Wang, Min-Dan; Zhai, Peng; Schreyer, David J.; Zheng, Ruo-Shi; Sun, Xiao-Dan; Cui, Fu-Zhai; Chen, Xiong-Biao

    2013-09-01

    Artificial tissue engineering scaffolds can potentially provide support and guidance for the regrowth of severed axons following nerve injury. In this study, a hybrid biomaterial composed of alginate and hyaluronic acid (HA) was synthesized and characterized in terms of its suitability for covalent modification, biocompatibility for living Schwann cells and feasibility to construct three dimensional (3D) scaffolds. Carbodiimide mediated amide formation for the purpose of covalent crosslinking of the HA was carried out in the presence of calciumions that ionically crosslink alginate. Amide formation was found to be dependent on the concentrations of carbodiimide and calcium chloride. The double-crosslinked composite hydrogels display biocompatibility that is comparable to simple HA hydrogels, allowing for Schwann cell survival and growth. No significant difference was found between composite hydrogels made from different ratios of alginate and HA. A 3D BioPlotter™ rapid prototyping system was used to fabricate 3D scaffolds. The result indicated that combining HA with alginate facilitated the fabrication process and that 3D scaffolds with porous inner structure can be fabricated from the composite hydrogels, but not from HA alone. This information provides a basis for continuing in vitro and in vivo tests of the suitability of alginate/HA hydrogel as a biomaterial to create living cell scaffolds to support nerve regeneration.

  3. Adding Chemical Cross-Links to a Physical Hydrogel

    OpenAIRE

    Ester Chiessi; Ivana Finelli; Barbara Cerroni; Gaio Paradossi

    2009-01-01

    Synergistic hydrogels are often encountered in polysaccharide mixtures widely used in food and biopharma products. The xanthan and konjac glucomannan pair provides one of the most studied synergistic hydrogels. Recently we showed that the junction zones stabilizing the 3D structure of this gel are present as macromolecular complexes in solution formed by the partially depolymerised polysaccharidic chains. The non-covalent interactions stabilizing the structure of the polysaccharidic complex c...

  4. Maleimide-grafted cellulose nanocrystals as cross-linkers for bionanocomposite hydrogels.

    Science.gov (United States)

    García-Astrain, C; González, K; Gurrea, T; Guaresti, O; Algar, I; Eceiza, A; Gabilondo, N

    2016-09-20

    This article deals with the preparation of bionanocomposite hydrogels from natural polymers and nanoentities, an emerging class of materials for biotechnological and biomedical applications. Herein, the applicability of the Diels-Alder "click" reaction to the design of bionanocomposite hydrogels from furan modified gelatin using maleimide-functionalized cellulose nanocrystals as multifunctional cocross-linkers is demonstrated. The functionalization of cellulose nanocrystals with maleimide moieties was confirmed by XPS. The swelling and rheological properties of the resulting bionanocomposite confirmed the formation of hydrogel networks with covalently embedded nanoentities. The Diels-Alder reaction resulted in the formation of stiffer networks with lower swelling ratios due to the formation of additional cross-linking points. The designed "click" strategy proved to be a promising candidate for the formation of fully renewable bionanocomposite hydrogels. PMID:27261734

  5. Smart nanocomposite hydrogels based on azo crosslinked graphene oxide for oral colon-specific drug delivery

    Science.gov (United States)

    Hou, Lin; Shi, Yuyang; Jiang, Guixiang; Liu, Wei; Han, Huili; Feng, Qianhua; Ren, Junxiao; Yuan, Yujie; Wang, Yongchao; Shi, Jinjin; Zhang, Zhenzhong

    2016-08-01

    A safe and efficient nanocomposite hydrogel for colon cancer drug delivery was synthesized using pH-sensitive and biocompatible graphene oxide (GO) containing azoaromatic crosslinks as well as poly (vinyl alcohol) (PVA) (GO–N=N–GO/PVA composite hydrogels). Curcumin (CUR), an anti-cancer drug, was encapsulated successfully into the hydrogel through a freezing and thawing process. Fourier transform infrared spectroscopy, scanning electron microscopy and Raman spectroscopy were performed to confirm the formation and morphological properties of the nanocomposite hydrogel. The hydrogels exhibited good swelling properties in a pH-sensitive manner. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely into the physiological environment of the stomach and small intestine. In vivo imaging analysis, pharmacokinetics and a distribution of the gastrointestinal tract experiment were systematically studied and evaluated as colon-specific drug delivery systems. All the results demonstrated that GO–N=N–GO/PVA composite hydrogels could protect CUR well while passing through the stomach and small intestine to the proximal colon, and enhance the colon-targeting ability and residence time in the colon site. Therefore, CUR loaded GO–N=N–GO/PVA composite hydrogels might potentially provide a theoretical basis for the treatment of colon cancer with high efficiency and low toxicity.

  6. Synthesis and properties of physically crosslinked poly (vinyl alcohol) hydrogels

    Institute of Scientific and Technical Information of China (English)

    MA Ru-yin; XIONG Dang-sheng

    2008-01-01

    The present study is an investigation of the properties of poly (vinyl alcohol), which would be a better contact lens material than conventional HEMA in some ways. A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent, DMSO, by the freezing-thawing method. The water content, visible light transmittance, mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles. The results show that the properties of PVA hydrogels depend on the polymer concentration, the number of freeze-thaw cycles and the addition of the organic solvent.

  7. Characterization of glycidyl methacrylate - crosslinked hyaluronan hydrogel scaffolds incorporating elastogenic hyaluronan oligomers.

    Science.gov (United States)

    Ibrahim, S; Kothapalli, C R; Kang, Q K; Ramamurthi, A

    2011-02-01

    Prior studies on two-dimensional cell cultures suggest that hyaluronic acid (HA) stimulates cell-mediated regeneration of extracellular matrix structures, specifically those containing elastin, though such biologic effects are dependent on HA fragment size. Towards being able to regenerate three-dimensional (3-D) elastic tissue constructs, the present paper studies photo-crosslinked hydrogels containing glycidyl methacrylate (GM)-derivatized bio-inert high molecular weight (HMW) HA (1 × 10(6)Da) and a bioactive HA oligomer mixture (HA-o: MW ∼0.75 kDa). The mechanical (rheology, degradation) and physical (apparent crosslinking density, swelling ratio) properties of the gels varied as a function of incorporated HA oligomer content; however, overall, the mechanics of these hydrogels were too weak for vascular applications as stand-alone materials. Upon in vivo subcutaneous implantation, only a few inflammatory cells were evident around GM-HA gels, however their number increased as HA-o content within the gels increased, and the collagen I distribution was uniform. Smooth muscle cells (SMC) were encapsulated into GM hydrogels, and calcein acetoxymethyl detection revealed that the cells were able to endure twofold the level of UV exposure used to crosslink the gels. After 21 days of culture, SMC elastin production, measured by immunofluorescence quantification, showed HA-o to increase cellular deposition of elastic matrix twofold relative to HA-o-free GM-HA gels. These results demonstrate that cell response to HA/HA-o is not altered by their methacrylation and photo-crosslinking into a hydrogel, and that HA-o incorporation into cell-encapsulating hydrogel scaffolds can be useful for enhancing their production of elastic matrix structures in a 3-D space, important for regenerating elastic tissues. PMID:20709199

  8. Dual crosslinked iminoboronate-chitosan hydrogels with strong antifungal activity against Candida planktonic yeasts and biofilms.

    Science.gov (United States)

    Ailincai, Daniela; Marin, Luminita; Morariu, Simona; Mares, Mihai; Bostanaru, Andra-Cristina; Pinteala, Mariana; Simionescu, Bogdan C; Barboiu, Mihai

    2016-11-01

    Chitosan based hydrogels are a class of cross-linked materials intensely studied for their biomedical, industrial and environmental application, but their biomedical use is limited because of the toxicity of different organic crosslinkers. To overcome this disadvantage, a new strategy to produce supramolecular chitosan hydrogels using low molecular weight compounds able to form covalent linkages and H-bonds to give a dual crosslinking is proposed. For this purpose we used 2-formylphenylboronic acid, which brings the advantage of imine stabilization via iminoboronate formation and potential antifungal activity due to the presence of boric acid residue. FTIR and NMR spectroscopy indicated that the gelling process took place by chemo-physical crosslinking forming a dual iminoboronate-chitosan network. Further, X-ray diffraction demonstrated a three-dimensional nanostructuring of the iminoboronate network with consequences on the micrometer-scale morphology and on the improvement of mechanical properties, as demonstrated by SEM and rheological investigation. The hydrogels proved strong antifungal activity against Candida planktonic yeasts and biofilms, promising to be a friendly treatment of the recurrent vulvovaginitis infections. PMID:27516277

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

    DEFF Research Database (Denmark)

    Liu, Chao; Thormann, Esben; Tyrode, Eric;

    2015-01-01

    Interactions between a silica surface and a surface coated with a grafted cross-linked hydrogel made from chitosan/PAA multilayers are investigated, utilizing colloidal probe atomic force microscopy. Attractive double-layer forces are found to dominate the long-range interaction over a broad range...... of pH and ionic strength conditions. The deduced potential at the hydrogel/aqueous interface is found to be very low. This situation is maintained in the whole pH-range investigated, even though the degree of protonation of chitosan changes significantly. This demonstrates that pH-variations change...

  10. Bioprinting vessel-like constructs using hyaluronan hydrogels crosslinked with tetrahedral polyethylene glycol tetracrylates.

    Science.gov (United States)

    Skardal, Aleksander; Zhang, Jianxing; Prestwich, Glenn D

    2010-08-01

    Bioprinting enables deposition of cells and biomaterials into spatial orientations and complexities that mirror physiologically relevant geometries. To facilitate the development of bioartificial vessel-like grafts, two four-armed polyethylene glycol (PEG) derivatives with different PEG chain lengths, TetraPEG8 and TetraPEG13, were synthesized from tetrahedral pentaerythritol derivatives. The TetraPEGs are unique multi-armed PEGs with a compact and symmetrical core. The TetraPEGs were converted to tetra-acrylate derivatives (TetraPAcs) which were used in turn to co-crosslink thiolated hyaluronic acid and gelatin derivatives into extrudable hydrogels for printing tissue constructs. First, the hydrogels produced by TetraPAc crosslinking showed significantly higher shear storage moduli when compared to PEG diacrylate (PEGDA)-crosslinked synthetic extracellular matrices (sECMs) of similar composition. These stiffer hydrogels have rheological properties more suited to bioprinting high-density cell suspensions. Second, TetraPAc-crosslinked sECMs were equivalent or superior to PEGDA-crosslinked gels in supporting cell growth and proliferation. Third, the TetraPac sECMs were employed in a proof-of-concept experiment by encapsulation of NIH 3T3 cells in sausage-like hydrogel macrofilaments. These macrofilaments were then printed into tubular tissue constructs by layer-by-layer deposition using the Fab@Home printing system. LIVE/DEAD viability/cytotoxicity-stained cross-sectional images showed the bioprinted cell structures to be viable in culture for up to 4 weeks with little evidence of cell death. Thus, biofabrication of cell suspensions in TetraPAc sECMs demonstrates the feasibility of building bioartificial blood vessel-like constructs for research and potentially clinical uses. PMID:20546891

  11. Sustained release of diltiazem hydrochloride from cross-linked biodegradable IPN hydrogel beads of pectin and modified xanthan gum

    OpenAIRE

    Giri, T. K.; Choudhary, C.; Alexander, A.; Ajazuddin,; Badwaik, H.; Tripathy, M.; Tripathi, D. K.

    2013-01-01

    Interpenetrating polymer network hydrogel beads of pectin and sodium carboxymethyl xanthan were prepared by ionotropic gelation with Al +3 ions and covalent cross-linking with glutaraldehyde for sustained delivery of diltiazem hydrochloride. Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning colorimetry and scanning electron microscopy were used to characterise the hydrogel beads. The swelling of the hydrogel and the release of drug were relatively low in pH 1.2...

  12. Controlled Aloin Release from Crosslinked Polyacrylamide Hydrogels: Effects of Mesh Size, Electric Field Strength and a Conductive Polymer

    OpenAIRE

    Anuvat Sirivat; Amornrat Niansiri; Sumonman Niamlang; Tawansorn Buranut

    2013-01-01

    The aim of this paper is to investigate the effects of hydrogel mesh size, a conductive polymer, and electric field strength on controlled drug delivery phenomena using drug-loaded polyacrylamide hydrogels prepared at various crosslinking ratios both with and without a conductive polymer system. Poly(p-phenylene vinylene), PPV, as the model conductive polymer, was used to study its ability to control aloin released from aloin-doped poly(p-phenylene vinylene)/polyacrylamide hydrogel (aloin-dop...

  13. Biomimetic PEG hydrogels crosslinked with minimal plasmin-sensitive tri-amino acid peptides

    OpenAIRE

    Jo, Suk Jo; Rizzi, Simone C.; Ehrbar, Martin; Weber, Franz E.; Hubbell, Jeffrey A.; Lutolf, Matthias P.

    2010-01-01

    Semi-synthetic, proteolytically degradable polymer hydrogels have proven effective as scaffolds to augment bone and skin regeneration in animals. However, high costs due to expensive peptide building blocks pose a significant hurdle towards broad clinical usage of these materials. Here we demonstrate that tri-amino acid peptides bearing lysine (or arginine), flanked by two cysteine residues for crosslinking, are adequate as minimal plasmin-sensitive peptides in poly(ethylene glycol)-based hyd...

  14. Highly robust chitosan hydrogels via a fast, simple and biocompatible dual crosslinking-based process

    OpenAIRE

    Costa, A.M.S.; Mano, J. F.

    2015-01-01

    Load-bearing soft tissues such as cartilage, blood vessels and muscles are able to withstand a remarkable compressive stress of several MPa without fracturing. Interestingly, most of these structural tissues are mainly composed of water and in this regard, hydrogels, as highly hydrated 3D-crosslinked polymeric networks, constitute a promising class of materials to repair lesions on these tissues. Although several approaches can be employed to shape the mechanical properties of artificial hydr...

  15. Starch-chitosan hydrogels prepared by reductive alkylation cross-linking

    OpenAIRE

    Baran, E. T.; Mano, J. F.; Reis, R. L.

    2004-01-01

    Starch–chitosan hydrogels were produced by oxidation of soluble starch to produce polyaldehyde and subsequently cross-linked with chitosan via reductive alkylation. The swelling ratio of starch–chitosan membranes was increased gradually with increasing starch ratio, but it was always lower than the native chitosan. In dry state, starch–chitosan membranes with low starch ratio (0.16, 0.38) showed similar tensile strength values to those of native chitosan while these values decreased with incr...

  16. Rheological characterization of cataplasm bases composed of cross-linked partially neutralized polyacrylate hydrogel.

    Science.gov (United States)

    Wang, Jian; Zhang, Hongqin; An, Dianyun; Yu, Jian; Li, Wei; Shen, Teng; Wang, Jianxin

    2014-10-01

    Viscoelasticity is a useful parameter for characterizing the intrinsic properties of the cross-linked polyacrylate hydrogel used in cataplasm bases. The aim of this study was to investigate the effects of various formulation parameters on the rheological characteristics of polyacrylate hydrogel. The hydrogel layers were formed using a partially neutralized polyacrylate (Viscomate(™)), which contained acrylic acid and sodium acrylate in different copolymerization ratios, as the cross-linked gel framework. Dihydroxyaluminum aminoacetate (DAAA), which produces aluminum ions, was used as the cross-linking agent. Rheological analyses were performed using a "stress amplitude sweep" and a "frequency sweep". The results showed that greater amounts of acrylic acid in the structure of Viscomate as well as higher concentrations of DAAA and Viscomate led to an increase in the elastic modulus (G'). However, greater amounts of acrylic acid in the structure of Viscomate and higher concentrations of DAAA had an opposite on the viscous modulus (G″); this might be owing to higher steric hindrance. The results of this study can serve as guidelines for the optimization of formulations for cataplasms. PMID:24865937

  17. Radiation synthesis of low swelling acrylamide based hydrogels and determination of average molecular weight between cross-links

    International Nuclear Information System (INIS)

    A comparative analysis of determination of cross-link density (νe) of hydrogels by using swelling tests and mechanical measurements has been made. Poly(acrylamide/methacrylamide) P(AAm/MAAm) and poly(acrylamide/hydroxyethyl methacrylate) P(AAm/HEMA) hydrogels were prepared by using gamma rays and used as model hydrogel systems. The uniaxial compression test was applied to cylindrical gel samples in the swollen state at pH 7. Stress-strain curves of hydrogels were evaluated to calculate the shear modulus values. The average molecular weight between cross-links (M-barc) and νe obtained from mechanical measurements were significantly different than the values obtained from swelling experiments. Large differences were attributed to the uncertainty on the value of the χ parameter used in the Flory-Rehner equation. ±1% change in this parameter doubled or reduced the M-barc value of hydrogel to half value

  18. 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.

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

    Science.gov (United States)

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

    2014-09-01

    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.

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

    International Nuclear Information System (INIS)

    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

  1. Preparation and properties of novel hydrogels from oxidized konjac glucomannan cross-linked chitosan for in vitro drug delivery.

    Science.gov (United States)

    Yu, Huiqun; Lu, Jun; Xiao, Chaobo

    2007-09-11

    In this paper, a novel composite hydrogel was prepared by the use of dialdehyde konjac glucomannan (DAK) as macromolecular cross-linking agent for chitosan (CS). This biocompatible material cross-links and gels in minutes. The structure and morphology were characterized by various analyses. The results indicate that the hydrogels formed through the Schiff-base reaction between the amino groups of CS chains and the aldehyde groups of DAK. The cross-link density (rho(x)) increases with the enhancement of DAK content in hydrogels, while equilibrium swelling ratio (SR) and the average molecular weight between cross-links (Mc) value decrease. Drug release was evaluated by varying the pH of the release medium, reversed dependence of release rate on the equilibrium SR of hydrogel indicated that drug release may be impeded by the association of drug with the polymer. Importantly, this process offers an entirely new window of materials preparation when compared with the traditional preparation of CS-based hydrogels with small molecules cross-linking agent. PMID:17665410

  2. Effects of cross-linking molecular weights in a hyaluronic acid-poly(ethylene oxide) hydrogel network on its properties

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Insup [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Kim, Gun-Woo [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Choi, Yoon-Jeong [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Kim, Mi-Sook [Department of Chemical Engineering, Seoul National University of Technology, 172 Gongnung-dong, Nowon-gu, Seoul 139-743 (Korea, Republic of); Park, Yongdoo [Korea Artificial Organ Center, Korea University, Seoul 136-705 (Korea, Republic of); Lee, Kyu-Back [Korea Artificial Organ Center, Korea University, Seoul 136-705 (Korea, Republic of); Kim, In-Sook [Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of); Hwang, Soon-Jung [Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of); Tae, Giyoong [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2006-09-15

    We examined the effects of cross-linking molecular weights on the properties of a hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel. Swelling behaviors, mechanical strength and rheological behaviors of the HA-PEO hydrogel were evaluated by employing different cross-linking molecular weights (100 kDa and 1.63 mDa) of the HAs in the hydrogel networks. The low molecular weight of HA was obtained in advance by treating high molecular weight HA with a hydrogen chloride solution. Methacrylation of HA was obtained by grafting aminopropylmethacrylate to its caroboxylic acid functional groups. While reduction of the HA molecular weights was confirmed by gel permeation chromatography, the degree of methacrylate grafting to the HA was measured by {sup 1}H-nuclear magnetic resonance. Synthesis of the HA-PEO hydrogel was successfully achieved via the Michael-type addition reaction between the methacrylate arm groups in the HA and the six thiol groups in PEO. The hydrogel formation was not dependent upon the HA molecular weights and its gelation behaviors were markedly different. Compared to the properties of the high molecular weight HA-based PEO one, the low molecular weight HA-based hydrogel induced quicker hydrogelation, as observed from the behaviors of the elastic and viscous modulus. Furthermore, the low molecular weight HA-based hydrogel demonstrated stronger mechanical properties as measured with a texture analyzer, lower water absorption as measured with a microbalance and smaller pore sizes on its surface and cross section as observed with scanning electron microscopy. The information about the effects of the cross-linking molecular weights of the gel network on the properties of the HA-based PEO hydrogel may lead to better design of hydrogels, especially in tissue engineering applications.

  3. Effects of cross-linking molecular weights in a hyaluronic acid-poly(ethylene oxide) hydrogel network on its properties

    International Nuclear Information System (INIS)

    We examined the effects of cross-linking molecular weights on the properties of a hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel. Swelling behaviors, mechanical strength and rheological behaviors of the HA-PEO hydrogel were evaluated by employing different cross-linking molecular weights (100 kDa and 1.63 mDa) of the HAs in the hydrogel networks. The low molecular weight of HA was obtained in advance by treating high molecular weight HA with a hydrogen chloride solution. Methacrylation of HA was obtained by grafting aminopropylmethacrylate to its caroboxylic acid functional groups. While reduction of the HA molecular weights was confirmed by gel permeation chromatography, the degree of methacrylate grafting to the HA was measured by 1H-nuclear magnetic resonance. Synthesis of the HA-PEO hydrogel was successfully achieved via the Michael-type addition reaction between the methacrylate arm groups in the HA and the six thiol groups in PEO. The hydrogel formation was not dependent upon the HA molecular weights and its gelation behaviors were markedly different. Compared to the properties of the high molecular weight HA-based PEO one, the low molecular weight HA-based hydrogel induced quicker hydrogelation, as observed from the behaviors of the elastic and viscous modulus. Furthermore, the low molecular weight HA-based hydrogel demonstrated stronger mechanical properties as measured with a texture analyzer, lower water absorption as measured with a microbalance and smaller pore sizes on its surface and cross section as observed with scanning electron microscopy. The information about the effects of the cross-linking molecular weights of the gel network on the properties of the HA-based PEO hydrogel may lead to better design of hydrogels, especially in tissue engineering applications

  4. Graphene Oxide/Polyacrylamide/Aluminum Ion Cross-Linked Carboxymethyl Hemicellulose Nanocomposite Hydrogels with Very Tough and Elastic Properties.

    Science.gov (United States)

    Kong, Weiqing; Huang, Danyang; Xu, Guibin; Ren, Junli; Liu, Chuanfu; Zhao, Lihong; Sun, Runcang

    2016-06-01

    Development of high-strength hydrogels has recently attracted ever-increasing attention. In this work, a new design strategy has been proposed to prepare graphene oxide (GO)/polyacrylamide (PAM)/aluminum ion (Al(3+) )-cross-linked carboxymethyl hemicellulose (Al-CMH) nanocomposite hydrogels with very tough and elastic properties. GO/PAM/Al-CMH hydrogels were synthesized by introducing graphene oxide (GO) into PAM/CMH hydrogel, followed by ionic cross-linking of Al(3+) . The nanocomposite hydrogels were characterized by means of FTIR, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDX) along with their swelling and mechanical properties. The maximum compressive strength and the Young's modulus of GO3.5 /PAM/Al-CMH0.45 hydrogel achieved values of up to 1.12 and 13.27 MPa, increased by approximately 6488 and 18330 % relative to the PAM hydrogel (0.017 and 0.072 MPa). The as-prepared GO/PAM/Al-CMH nanocomposite hydrogels possess high strength and great elasticity giving them potential in bioengineering and drug-delivery system applications. PMID:27062081

  5. Tough biodegradable mixed-macromer networks and hydrogels by photo-crosslinking in solution.

    Science.gov (United States)

    Zant, Erwin; Grijpma, Dirk W

    2016-02-01

    The preparation of polymeric networks that are both tough and biodegradable remains a challenge. Here we show a very straightforward method to produce tough biodegradable networks from low molecular weight macromers for applications such as tissue engineering. Photo-crosslinking combinatorial mixtures of methacrylate-functionalized poly(1,3-trimethylene carbonate) (PTMC), poly(d,l-lactide) (PDLLA), poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG) oligomers in propylene carbonate (PC) allowed the preparation of network films with excellent tensile characteristics and resistance to tearing. This method enabled the production of both very tough mixed-macromer elastomers as well as mixed-macromer hydrogels. A mixed-macromer hydrogel prepared from 33wt.% PTMC, 33wt.% PCL and 33wt.% PEG had a very high tearing energy of 0.81kJ/m(2), which is comparable to tearing energies determined for articular cartilage. PMID:26687979

  6. The influence of hyaluronic acid hydrogel crosslinking density and macromolecular diffusivity on human MSC chondrogenesis and hypertrophy.

    Science.gov (United States)

    Bian, Liming; Hou, Chieh; Tous, Elena; Rai, Reena; Mauck, Robert L; Burdick, Jason A

    2013-01-01

    Hyaluronic acid (HA) hydrogels formed via photocrosslinking provide stable 3D hydrogel environments that support the chondrogenesis of mesenchymal stem cells (MSCs). Crosslinking density has a significant impact on the physical properties of hydrogels, including their mechanical stiffness and macromolecular diffusivity. Variations in the HA hydrogel crosslinking density can be obtained by either changes in the HA macromer concentration (1, 3, or 5% w/v at 15 min exposure) or the extent of reaction through light exposure time (5% w/v at 5, 10, or 15 min). In this work, increased crosslinking by either method resulted in an overall decrease in cartilage matrix content and more restricted matrix distribution. Increased crosslinking also promoted hypertrophic differentiation of the chondrogenically induced MSCs, resulting in more matrix calcification in vitro. For example, type X collagen expression in the high crosslinking density 5% 15 min group was ~156 and 285% higher when compared to the low crosslinking density 1% 15 min and 5% 5 min groups on day 42, respectively. Supplementation with inhibitors of the small GTPase pathway involved in cytoskeletal tension or myosin II had no effect on hypertrophic differentiation and matrix calcification, indicating that the differential response is unlikely to be related to force-sensing mechanotransduction mechanisms. When implanted subcutaneously in nude mice, higher crosslinking density again resulted in reduced cartilage matrix content, restricted matrix distribution, and increased matrix calcification. This study demonstrates that hydrogel properties mediated through alterations in crosslinking density must be considered in the context of the hypertrophic differentiation of chondrogenically induced MSCs. PMID:23084553

  7. Electron Beam Synthesis and Characterization of Acrylamide/Acrylic Acid Hydrogels Using Trimethylolpropane Trimethacrylate as Cross-Linker

    Directory of Open Access Journals (Sweden)

    Gabriela Craciun

    2016-01-01

    Full Text Available The purpose of the paper is to present the synthesis and characterization of hydrogels prepared by free-radical copolymerization of acrylamide and acrylic acid in aqueous solutions using potassium persulfate as initiator and trimethylolpropane trimethacrylate as cross-linker, via the radiation technique. The samples were subjected to electron beam treatment in the dose range of 2 to 4 kGy and the influence of the absorbed dose and amount of cross-linker on the swelling properties, diffusion coefficient, and network parameters of hydrogels was investigated. A possible reaction mechanism for acrylamide/acrylic acid/trimethylolpropane trimethacrylate hydrogels was also suggested. The structure and morphology of hydrogels were characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy.

  8. Influence of natural and synthetic crosslinking reagents on the structural and mechanical properties of chitosan-based hybrid hydrogels.

    Science.gov (United States)

    Garnica-Palafox, I M; Sánchez-Arévalo, F M

    2016-10-20

    The objective of this work was to correlate the physical and chemical properties of chitosan/poly(vinyl alcohol)/genipin (CS/PVA/GEN) and chitosan/poly(vinyl alcohol)/glutaraldehyde (CS/PVA/GA) hydrogels with their structural and mechanical responses. In addition, their molecular structures were determined and confirmed using FTIR spectroscopy. The results indicated that the hybrid hydrogels crosslinked with genipin showed similar crystallinity, thermal properties, elongation ratio and structural parameters as those crosslinked with glutaraldehyde. However, it was found that the elastic moduli of the two hybrid hydrogels were slightly different: 2.82±0.33MPa and 2.08±0.11MPa for GA and GEN, respectively. Although the hybrid hydrogels crosslinked with GEN presented a lower elastic modulus, the main advantage is that GEN is five to ten thousand times less cytotoxic than GA. This means that the structural and mechanical properties of hybrid hydrogels crosslinked with GEN can easily be tuned and could have potential applications in the tissue engineering, regenerative medicine, food, agriculture and environmental industries. PMID:27474657

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

    International Nuclear Information System (INIS)

    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)

  10. Synthesis of crosslinked hydrogel polyethylene oxide and immobilization of antibiotic induced by using gamma radiation for wound dressing applications

    International Nuclear Information System (INIS)

    The aim of this work was to study of the physico properties of crosslinked poly (ethylene oxide) (PEO) hydrogel produced by gamma and its potential use for drug release in order to be applied as a wound dressing. A crosslinked PEO hydrogel was prepared in the matrix form using PEO polymer via radiation polymerization. A series of PEO hydrogels with different compositions (1-7 % w/v) at an irradiation dose of 20-40 kGy were prepared. The gel content and swelling ratio studies were conducted by gravimetry. The maximum gel content of hydrogel ∼ 95 % at a dose of 40 kGy, and the swelling ratio maximum of 10-15 g/g was reached in about 8 h at the dose of 20 kGy. Drug release experiments were performed in a continually release system using model drug (tetracycline) loaded PEO hydrogel measured by UV-Vis spectrophotometry. A specific PEO hydrogel formulation possessing the highest PEO content (7 % w/v) and loaded with 10 mg antibiotic released range of 80-90 % of the total loaded drug in 24 h at pH 7.4 in distilled water. This hydrogels could be considered as a potential candidate for antibiotic carrier in wound dressing and or transdermal applications. (author)

  11. Production of Prednisolone by Pseudomonas oleovorans Cells Incorporated Into PVP/PEO Radiation Crosslinked Hydrogels

    Directory of Open Access Journals (Sweden)

    Abeer Abd El-Hady

    2004-01-01

    Full Text Available In order to rise the yield of prednisolone from hydrocortisone, the Pseudomonas oleovorans cells were entrapped into radiation crosslinked poly (vinyl pyrrolidone/poly(ethylene oxide (PVP/PEO hydrogel of different gel contents. The factors affecting the gel content and swelling behavior of the polymeric gel, such as polymer composition, polymer blend concentration, and irradiation doses, were investigated. The formation of gels having a good strength with the ability to retain a desirable amount of water in their three-dimensional network can be achieved by using PVP/PEO copolymer of composition (90:10 and concentration of 15% prepared at 20 kGy irradiation dose. At these conditions the prepared hydrogel is considered the most favorable one that gave the highest hydrocortisone bioconversion and prednisolone yield, 81% and 62.8%, respectively. The improvement of prednisolone yield was also achieved by increasing substrate concentration. Maximum hydrocortisone bioconversion (86.44 was obtained at 18 hours by using substrate concentration of 30 mg. Reusability of immobilized Pseudomonas oleovorans entrapped into PVP/PEO copolymer hydrogel was studied. The results indicated that the transformation capacity of hydrocortisone to prednisolone highly increased by the repeated use of copolymer for 4 times. This was accompanied by an increase in prednisolone yield to 89% and the bioconversion of hydrocortisone was 98.8%.

  12. Self-reinforcement and protein sustained delivery of hyaluronan hydrogel by tailoring a dually cross-linked network

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chunhong; Xu, Guoguang; Wang, Xinghui [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Tu, Mei; Zeng, Rong; Rong, Jianhua [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhao, Jianhao, E-mail: jhzhao@jnu.edu.cn [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2015-01-01

    A series of self-reinforcing hyaluronan hydrogels were developed to improve mechanical properties and protein sustained delivery thanks to a dually cross-linked network. Hyaluronan gel particles (HGPs, 1–5 μm in diameter) with different cross-linking densities, i.e. HGPs-1.5, HGPs-3 and HGPs-15, were prepared in an inverse emulsion system and used as the reinforcing phase after glycidyl methacrylation, while glycidyl methacrylated hyaluronan with a substitution degree of 45.2% was synthesized as the matrix phase. These two phases were cross-linked under ultraviolet irradiation to form self-reinforcing hyaluronan hydrogels (srHAs) that showed typical cross-linked structure of HGPs connecting the matrix phase by cross-section observation. In comparison to hyaluronan bulk gels and their blends with HGPs, srHAs distinctly enhanced the mechanical properties and BSA long-term sustained delivery, especially srHA-1.5 showed the highest compressive modulus of 220 ± 15 kPa and the slowest BSA delivery (67% release at 14 d). The 3T3 fibroblast cell culture showed that all the srHAs had no cytotoxicity. - Highlights: • New self-reinforcing HA hydrogels with a dually cross-linked network were developed. • Self-reinforcing HA hydrogels greatly enhanced the mechanical properties. • Self-reinforcing HA hydrogels prolonged the sustained delivery of BSA. • The self-reinforcing mechanism and BSA diffusion mechanism were discussed. • Self-reinforcing HA hydrogels had no cytotoxicity to 3T3 fibroblast cells.

  13. Self-reinforcement and protein sustained delivery of hyaluronan hydrogel by tailoring a dually cross-linked network

    International Nuclear Information System (INIS)

    A series of self-reinforcing hyaluronan hydrogels were developed to improve mechanical properties and protein sustained delivery thanks to a dually cross-linked network. Hyaluronan gel particles (HGPs, 1–5 μm in diameter) with different cross-linking densities, i.e. HGPs-1.5, HGPs-3 and HGPs-15, were prepared in an inverse emulsion system and used as the reinforcing phase after glycidyl methacrylation, while glycidyl methacrylated hyaluronan with a substitution degree of 45.2% was synthesized as the matrix phase. These two phases were cross-linked under ultraviolet irradiation to form self-reinforcing hyaluronan hydrogels (srHAs) that showed typical cross-linked structure of HGPs connecting the matrix phase by cross-section observation. In comparison to hyaluronan bulk gels and their blends with HGPs, srHAs distinctly enhanced the mechanical properties and BSA long-term sustained delivery, especially srHA-1.5 showed the highest compressive modulus of 220 ± 15 kPa and the slowest BSA delivery (67% release at 14 d). The 3T3 fibroblast cell culture showed that all the srHAs had no cytotoxicity. - Highlights: • New self-reinforcing HA hydrogels with a dually cross-linked network were developed. • Self-reinforcing HA hydrogels greatly enhanced the mechanical properties. • Self-reinforcing HA hydrogels prolonged the sustained delivery of BSA. • The self-reinforcing mechanism and BSA diffusion mechanism were discussed. • Self-reinforcing HA hydrogels had no cytotoxicity to 3T3 fibroblast cells

  14. Sustained release of diltiazem hydrochloride from cross-linked biodegradable IPN hydrogel beads of pectin and modified xanthan gum

    Directory of Open Access Journals (Sweden)

    T K Giri

    2013-01-01

    Full Text Available Interpenetrating polymer network hydrogel beads of pectin and sodium carboxymethyl xanthan were prepared by ionotropic gelation with Al +3 ions and covalent cross-linking with glutaraldehyde for sustained delivery of diltiazem hydrochloride. Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning colorimetry and scanning electron microscopy were used to characterise the hydrogel beads. The swelling of the hydrogel and the release of drug were relatively low in pH 1.2 buffer solutions. However, higher swelling and drug release were observed in pH 6.8 buffer solutions. The carboxyl functional groups of hydrogels undergo ionisation and the osmotic pressure inside the beads increases resulting in higher swelling and drug release in higher pH. The release of drug depends on concentration of polymer, amount and exposure time of cross-linker and drug content in the hydrogel matrices. The present study indicated that the hydrogel beads minimised the drug release in pH 1.2 buffer solutions and to prolong the drug release in pH 6.8 buffer solutions.

  15. Sustained Release of Diltiazem Hydrochloride from Cross-linked Biodegradable IPN Hydrogel Beads of Pectin and Modified Xanthan Gum.

    Science.gov (United States)

    Giri, T K; Choudhary, C; Alexander, A; Ajazuddin; Badwaik, H; Tripathy, M; Tripathi, D K

    2013-11-01

    Interpenetrating polymer network hydrogel beads of pectin and sodium carboxymethyl xanthan were prepared by ionotropic gelation with Al(+3) ions and covalent cross-linking with glutaraldehyde for sustained delivery of diltiazem hydrochloride. Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning colorimetry and scanning electron microscopy were used to characterise the hydrogel beads. The swelling of the hydrogel and the release of drug were relatively low in pH 1.2 buffer solutions. However, higher swelling and drug release were observed in pH 6.8 buffer solutions. The carboxyl functional groups of hydrogels undergo ionisation and the osmotic pressure inside the beads increases resulting in higher swelling and drug release in higher pH. The release of drug depends on concentration of polymer, amount and exposure time of cross-linker and drug content in the hydrogel matrices. The present study indicated that the hydrogel beads minimised the drug release in pH 1.2 buffer solutions and to prolong the drug release in pH 6.8 buffer solutions. PMID:24591735

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

    Science.gov (United States)

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

    2016-10-20

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Sheikh, N., E-mail: nasheikh@aeoi.org.i [Radiation Applications Research School, Nuclear Science and Technology Research Institute, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of); Jalili, L. [Polymer group, Technology and Engineering Department, Yazd University, Yazd (Iran, Islamic Republic of); Anvari, F. [Radiation Applications Research School, Nuclear Science and Technology Research Institute, Yazd (Iran, Islamic Republic of)

    2010-06-15

    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).

  18. DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels

    Directory of Open Access Journals (Sweden)

    Anatoly Zinchenko

    2015-03-01

    Full Text Available A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i solubilization of multi-walled carbon nanotubes (MWCNT in aqueous solution of DNA, and (ii chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed.

  19. Synthesis,characterization and swelling properties of a chemically cross-linked poly(vinyl alcohol) hydrogel

    Institute of Scientific and Technical Information of China (English)

    LI Wenbo; XUE Feng; CHENG Rongshi

    2007-01-01

    A poly(vinyl alcohol) hydrogel was prepared by coupling poly(vinyl alcohol) with epichlorohydrin as the cross-linking agent.The structure of the hydrogel was characterized by FTIR and GPC techniques.Various amounts of water were added into the dry gel to swell it,and the quantity of water in various states in the partially swollen hydrogel was determined by DSC technique.The analytical results indicate that the water introduced into the dry gel first combines with the hydrophilic groups of the network chains through hydrogen bond forming non-freezable water.The weight ratio of the non-freezable water to dry gel in the hydrogels is about 0.20.After the non-freezable water is saturated,the additional water penetrates the network space and exists simultaneously both in the freezable and free water states until reaching equilibrium swelling.

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

    Science.gov (United States)

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

    2016-01-01

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

  1. Poly(ethylene glycol) dicarboxylate/poly(ethylene oxide) hydrogel film co-crosslinked by electron beam irradiation as an anti-adhesion barrier

    Energy Technology Data Exchange (ETDEWEB)

    Haryanto,; Singh, Deepti; Han, Sung Soo [Department of Advanced Organic Materials Engineering, Yeungnam University, Gyongbuk 712-749 (Korea, Republic of); Son, Jun Hyuk [Department of Ophthalmology, College of Medicine, Yeungnam University, Gyongbuk 712-749 (Korea, Republic of); Kim, Seong Cheol, E-mail: sckim07@ynu.ac.kr [Department of Advanced Organic Materials Engineering, Yeungnam University, Gyongbuk 712-749 (Korea, Republic of)

    2015-01-01

    The cross-linked poly(ethylene glycol) dicarboxylate (PEGDC)/poly(ethylene oxide) (PEO) and poly(ethylene glycol) dimethacrylate (PEGDMA)/(PEO) hydrogels were developed for possible biomedical applications such as an anti-adhesion barrier. Various contents of PEGDC/PEO film were irradiated using an electron beam with various beam intensities in order to obtain various degrees of crosslinked hydrogels. The optimum dose (300 kGy) and total crosslinker content of 10% were used to prepare crosslinked hydrogel films with three different compositions (10% PEGDC, 10% PEGDMA, 5% PEGDC–5% PEGDMA). Among them, 10% PEGDC hydrogel film exhibited the highest elongation at break (69.33 ± 6.87%) with high mechanical strength. 10% PEGDC hydrogel film showed the lowest hemolysis activity (6.03 ± 0.01%) and the highest tissue adherence (75.67 ± 1.15 cN). The result also indicated that the carboxyl groups in PEGDC affect the tissue adherence of hydrogel films via H-bonding interactions. In animal studies, 10% PEGDC anti-adhesion hydrogel film degraded within 3 weeks and demonstrated better anti-adhesive effect compared to Guardix-SG®. - Highlights: • The crosslinked PEGDC/PEO hydrogel was developed by e-beam irradiation. • 10% PEGDC hydrogel film showed the highest elongation at break and tissue adhesion. • The COOH group enhanced the tissue adherence of hydrogel films on the intestine. • 10% PEGDC hydrogel film demonstrated a good anti-adhesive effect in animal study. • All of the hydrogel films with 10% PEGDC degraded in vivo within three weeks.

  2. Poly(ethylene glycol) dicarboxylate/poly(ethylene oxide) hydrogel film co-crosslinked by electron beam irradiation as an anti-adhesion barrier

    International Nuclear Information System (INIS)

    The cross-linked poly(ethylene glycol) dicarboxylate (PEGDC)/poly(ethylene oxide) (PEO) and poly(ethylene glycol) dimethacrylate (PEGDMA)/(PEO) hydrogels were developed for possible biomedical applications such as an anti-adhesion barrier. Various contents of PEGDC/PEO film were irradiated using an electron beam with various beam intensities in order to obtain various degrees of crosslinked hydrogels. The optimum dose (300 kGy) and total crosslinker content of 10% were used to prepare crosslinked hydrogel films with three different compositions (10% PEGDC, 10% PEGDMA, 5% PEGDC–5% PEGDMA). Among them, 10% PEGDC hydrogel film exhibited the highest elongation at break (69.33 ± 6.87%) with high mechanical strength. 10% PEGDC hydrogel film showed the lowest hemolysis activity (6.03 ± 0.01%) and the highest tissue adherence (75.67 ± 1.15 cN). The result also indicated that the carboxyl groups in PEGDC affect the tissue adherence of hydrogel films via H-bonding interactions. In animal studies, 10% PEGDC anti-adhesion hydrogel film degraded within 3 weeks and demonstrated better anti-adhesive effect compared to Guardix-SG®. - Highlights: • The crosslinked PEGDC/PEO hydrogel was developed by e-beam irradiation. • 10% PEGDC hydrogel film showed the highest elongation at break and tissue adhesion. • The COOH group enhanced the tissue adherence of hydrogel films on the intestine. • 10% PEGDC hydrogel film demonstrated a good anti-adhesive effect in animal study. • All of the hydrogel films with 10% PEGDC degraded in vivo within three weeks

  3. Poly (vinyl alcohol-alginate physically crosslinked hydrogel membranes for wound dressing applications: Characterization and bio-evaluation

    Directory of Open Access Journals (Sweden)

    Elbadawy A. Kamoun

    2015-01-01

    Full Text Available PVA-sodium alginate (SA hydrogel membranes containing sodium ampicillin as a topical antibiotic were developed using the freeze–thawing method for wound dressing application. Aqueous solution of sodium alginate has been blended in a certain ratio with PVA, followed by the crosslinking method has been conducted by freeze–thawing method as physical crosslinking instead of the use of traditional chemical crosslinking to avoid riskiness of chemical reagents and crosslinkers. The physicochemical properties of PVA-SA membranes e.g. gel fraction and water uptake % have been performed. Increased SA content with PVA decreased gel fraction, elasticity, and elongation to break of PVA-SA membranes. However, it resulted in an increase in swelling degree, protein adsorption, and roughness of membrane surface. High SA content in PVA membranes had apparently an impact on surface morphology structure of hydrogel membranes. Pore size and pore area distribution have been observed with addition of high SA concentration. However, high SA content had an insignificant effect on the release of ampicillin. The hydrolytic degradation of PVA-SA membranes has prominently increased with increasing SA content. Furthermore, hemolysis (% and in vitro inhibition (% for both Gram positive and negative bacteria have been sharply affected by addition of SA into PVA, indicating the improved blood hemocompatibility. Thus, PVA-SA hydrogel membrane based wound dressing system containing ampicillin could be a good polymeric membrane candidate in wound care.

  4. Self-Healing and Thermo-Responsive Dual-Crosslinked Alginate Hydrogels based on Supramolecular Inclusion Complexes

    OpenAIRE

    Miao, Tianxin; Fenn, Spencer L.; Charron, Patrick N.; Oldinski, Rachael A.

    2015-01-01

    β-cyclodextrin (β-CD), with a lipophilic inner cavity and hydrophilic outer surface, interacts with a large variety of non-polar guest molecules to form non-covalent inclusion complexes. Conjugation of β-CD onto biomacromolecules can form physically-crosslinked hydrogel networks upon mixing with a guest molecule. Herein describes the development and characterization of self-healing, thermo-responsive hydrogels, based on host-guest inclusion complexes between alginate-graft-β-CD and Pluronic® ...

  5. Thermally Reversible Physically Cross-Linked Hybrid Network Hydrogels Formed by Thermosensitive Hairy Nanoparticles.

    Science.gov (United States)

    Wright, Roger A E; Henn, Daniel M; Zhao, Bin

    2016-08-18

    This Article reports on thermally induced reversible formation of physically cross-linked, three-dimensional network hydrogels from aqueous dispersions of thermosensitive diblock copolymer brush-grafted silica nanoparticles (hairy NPs). The hairy NPs consisted of a silica core, a water-soluble polyelectrolyte inner block of poly(2-(methacryloyloxy)ethyltrimethylammonium iodide), and a thermosensitive poly(methoxydi(ethylene glycol) methacrylate) (PDEGMMA) outer block synthesized by sequential surface-initiated atom transfer radical polymerizations and postpolymerization quaternization of tertiary amine moieties. Moderately concentrated dispersions of these hairy nanoparticles in water underwent thermally induced reversible transitions between flowing liquids to self-supporting gels upon heating. The gelation was driven by the lower critical solution temperature (LCST) transition of the PDEGMMA outer block, which upon heating self-associated into hydrophobic domains acting as physical cross-linking points for the gel network. Rheological studies showed that the sol-gel transition temperature decreased with increasing hairy NP concentration, and the gelation was achieved at concentrations as low as 3 wt %. PMID:27455167

  6. Chemically Cross-Linked Poly(acrylic-co-vinylsulfonic Acid Hydrogel for the Delivery of Isosorbide Mononitrate

    Directory of Open Access Journals (Sweden)

    Talib Hussain

    2013-01-01

    Full Text Available We report synthesis, characterization, and drug release attributes of a series of novel pH-sensitive poly(acrylic-co-vinylsulfonic acid hydrogels. These hydrogels were prepared by employing free radical polymerization using ethylene glycol dimethacrylate (EGDMA and benzyl peroxide (BPO as cross-linker and initiator, respectively. Effect of acrylic acid (AA, polyvinylsulfonic acid (PVSA, and EGDMA on prepared hydrogels was investigated. All formulations showed higher swelling at high pHs and vice versa. Formulations containing higher content of AA and EGDMA show reduced swelling, but one with higher content of PVSA showed increased swelling. Hydrogel network was characterized by determining structural parameters and loaded with isosorbide mononitrate. FTIR confirmed absence of drug polymer interaction while DSC and TGA demonstrated molecular dispersion of drug in a thermally stable polymeric network. All the hydrogel formulations exhibited a pH dependent release of isosorbide mononitrate which was found to be directly proportional to pH of the medium and PVSA content and inversely proportional to the AA contents. Drug release data were fitted to various kinetics models. Results indicated that release of isosorbide mononitrate from poly(AA-co-VSA hydrogels was non-Fickian and that the mechanism was diffusion-controlled.

  7. Development of crosslinked methylcellulose hydrogels for soft tissue augmentation using an ammonium persulfate-ascorbic acid redox system.

    Science.gov (United States)

    Gold, Gittel T; Varma, Devika M; Taub, Peter J; Nicoll, Steven B

    2015-12-10

    Hydrogels composed of methylcellulose are candidate materials for soft tissue reconstruction. Although photocrosslinked methylcellulose hydrogels have shown promise for such applications, gels crosslinked using reduction-oxidation (redox) initiators may be more clinically viable. In this study, methylcellulose modified with functional methacrylate groups was polymerized using an ammonium persulfate (APS)-ascorbic acid (AA) redox initiation system to produce injectable hydrogels with tunable properties. By varying macromer concentration from 2% to 4% (w/v), the equilibrium moduli of the hydrogels ranged from 1.47 ± 0.33 to 5.31 ± 0.71 kPa, on par with human adipose tissue. Gelation time was found to conform to the ISO standard for injectable materials. Cellulase treatment resulted in complete degradation of the hydrogels within 24h, providing a reversible corrective feature. Co-culture with human dermal fibroblasts confirmed the cytocompatibility of the gels based on DNA measurements and Live/Dead imaging. Taken together, this evidence indicates that APS-AA redox-polymerized methylcellulose hydrogels possess properties beneficial for use as soft tissue fillers. PMID:26428151

  8. Preparation and Swelling Behavior of Physically Crosslinked Hydrogels Composed of Poly(vinyl alcohol)and Chitosan

    Institute of Scientific and Technical Information of China (English)

    HE Guanghua; ZHENG Hua; XIONG Fuliang

    2008-01-01

    The physically crosslinked poly(vinyl alcohol)/chitosan (CS) composite hydrogels were prepared by cyclic freezing/thawing techniques,and the microstructure and swelling behavior of the hydrogels in the simulated gastric (pH 1.0) and intestinal (pH 7.4) media were investigated.The experimental results of infrared spectra (IR),scanning electron microscope (SEM) and differential scanning calorimetry (DSC) demonstrated that poly(vinyl alcohol) and chitosan had good miscibility in the composite hydrogels,and the addition of chitosan perturbed the formation of poly(vinyl alcohol) crystallites.The swelling kinetics results indicated that the composite hydrogels had good pH sensitive properties to the acidic environments,and with the increase of chitosan content in the blend,the maximum swelling degreed and the swelling rate both increased,but it led to more dissolution at pH 1.0.And the composite hydrogels also exhibited good reversible swelling behavior with pH value of the swelling medium altering between 1.0 and 7.4.In addition,the higher freezing/thawing cycle times resulted in the lower swelling rate.Therefore,the swelling behavior of the composite hydrogels could be adjusted by changing the chitosan contents and the freezing/thawing cycle times.

  9. Temporal and spatial distribution of macrophage phenotype markers in the foreign body response to glutaraldehyde-crosslinked gelatin hydrogels.

    Science.gov (United States)

    Yu, Tony; Wang, Wenbo; Nassiri, Sina; Kwan, Thomas; Dang, Chau; Liu, Wei; Spiller, Kara L

    2016-06-01

    Currently, it is not well understood how changes in biomaterial properties affect the foreign body response (FBR) or macrophage behavior. Because failed attempts at biomaterial degradation by macrophages have been linked to frustrated phagocytosis, a defining feature of the FBR, we hypothesized that increased hydrogel crosslinking density (and decreased degradability) would exacerbate the FBR. Gelatin hydrogels were crosslinked with glutaraldehyde (0.05, 0.1, and 0.3%) and implanted subcutaneously in C57BL/6 mice over the course of 3 weeks. Interestingly, changes in hydrogel crosslinking did not affect the thickness of the fibrous capsule surrounding the hydrogels, expression of the pan-macrophage marker F480, expression of three macrophage phenotype markers (iNOS, Arg1, CD163), or expression of the myofibroblast marker aSMA, determined using semi-quantitative immunohistochemical analysis. With respect to temporal changes, the level of expression of the M1 marker (iNOS) remained relatively constant throughout the study, while the M2 markers Arg1 and CD163 increased over time. Expression of these M2 markers was highly correlated with fibrous capsule thickness. Differences in spatial distribution of staining also were noted, with the strongest staining for iNOS at the hydrogel surface and increasing expression of the myofibroblast marker aSMA toward the outer edge of the fibrous capsule. These results confirm previous reports that macrophages in the FBR exhibit characteristics of both M1 and M2 phenotypes. Understanding the effects (or lack of effects) of biomaterial properties on the FBR and macrophage phenotype may aid in the rational design of biomaterials to integrate with surrounding tissue. PMID:26902292

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

    International Nuclear Information System (INIS)

    This paper describes the development of a new crosslinking method for the synthesis of novel hydrogel films from chitosan and PVA for potential use in various biomedical applications. These hydrogel membranes were synthesized by blending different ratios of chitosan (CS) and poly(vinyl alcohol) (PVA) solutions and were crosslinked with 2.5% (w/v) triethyl orthoformate (TEOF) in the presence of 17% (w/v) sulfuric acid. The physical/chemical interactions and the presence of specific functional groups in the synthesized materials were evaluated by Fourier transform infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) proved that these crosslinked hydrogel films have good thermal stability which was decreased as the CS ratio was increased. Differential scanning calorimetry (DSC) exhibited that CS and PVA were present in the amorphous form. The solution absorption properties were performed in phosphate buffer saline (PBS) solution of pH 7.4. The 20% PVA–80% CS crosslinked hydrogel films showed a greater degree of solution absorption (183%) as compared to other compositions. The hydrogels with greater CS concentration (60% and 80%) demonstrated relatively more porous structure, better cell viability and proliferation and also revealed good blood clotting ability even after crosslinking. Based on the observed facts these hydrogels can be tailored for their potential utilization in wound healing and skin tissue engineering applications. - Highlights: • A new method for covalently crosslinking of chitosan and PVA. • Triethyl orthoformate (TEOF) a new polymer–polymer crosslinking agent. • Hydrogels displayed a good solution absorption capacity. • Hydrogels demonstrated good cytocompatibility. • Good blood clotting potential was shown by these scaffolds

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

    Energy Technology Data Exchange (ETDEWEB)

    Yar, Muhammad, E-mail: drmyar@ciitlahore.edu.pk [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Shahzad, Sohail [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Siddiqi, Saadat Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mahmood, Nasir [Department of Allied Health Sciences and Chemical Pathology, Department of Human Genetics and Molecular Biology, University of Health Sciences, Lahore (Pakistan); Rauf, Abdul [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Anwar, Muhammad Sabieh [Department of Physics, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences (LUMS), Opposite Sector U, D.H.A., Lahore 54792 (Pakistan); Chaudhry, Aqif Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rehman, Ihtesham ur [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Materials Science and Engineering, The Kroto Research Institute, The University of Sheffield, North Campus, Broad Lane, Sheffield S3 7HQ (United Kingdom)

    2015-11-01

    This paper describes the development of a new crosslinking method for the synthesis of novel hydrogel films from chitosan and PVA for potential use in various biomedical applications. These hydrogel membranes were synthesized by blending different ratios of chitosan (CS) and poly(vinyl alcohol) (PVA) solutions and were crosslinked with 2.5% (w/v) triethyl orthoformate (TEOF) in the presence of 17% (w/v) sulfuric acid. The physical/chemical interactions and the presence of specific functional groups in the synthesized materials were evaluated by Fourier transform infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) proved that these crosslinked hydrogel films have good thermal stability which was decreased as the CS ratio was increased. Differential scanning calorimetry (DSC) exhibited that CS and PVA were present in the amorphous form. The solution absorption properties were performed in phosphate buffer saline (PBS) solution of pH 7.4. The 20% PVA–80% CS crosslinked hydrogel films showed a greater degree of solution absorption (183%) as compared to other compositions. The hydrogels with greater CS concentration (60% and 80%) demonstrated relatively more porous structure, better cell viability and proliferation and also revealed good blood clotting ability even after crosslinking. Based on the observed facts these hydrogels can be tailored for their potential utilization in wound healing and skin tissue engineering applications. - Highlights: • A new method for covalently crosslinking of chitosan and PVA. • Triethyl orthoformate (TEOF) a new polymer–polymer crosslinking agent. • Hydrogels displayed a good solution absorption capacity. • Hydrogels demonstrated good cytocompatibility. • Good blood clotting potential was shown by these scaffolds.

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

    International Nuclear Information System (INIS)

    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

  13. Genipin Cross-Linked Chitosan-Polyvinylpyrrolidone Hydrogels: Influence of Composition and Postsynthesis Treatment on pH Responsive Behaviour

    Directory of Open Access Journals (Sweden)

    Chinyelumndu Jennifer Nwosu

    2015-01-01

    Full Text Available Understanding the factors that influence the pH responsive behaviour of biocompatible cross-linked hydrogel networks is essential when aiming to synthesise a mechanically stable and yet stimuli responsive material suitable for various applications including drug delivery and tissue engineering. In this study the behaviour of intelligent chitosan-polyvinylpyrrolidone-genipin cross-linked hydrogels is examined as a function of their composition and postsynthesis treatment. Hydrogels are synthesised with varying amounts of each component (chitosan, polyvinylpyrrolidone, and genipin and their response in a pH 2 buffer is measured optically. The influence of postsynthesis treatment on stability and smart characteristics is assessed using selected hydrogel samples synthesised at 30, 40, and 50°C. After synthesis, samples are exposed to either continuous freezing or three freeze-thaw cycles resulting in increased mechanical stability for all samples. Further morphological and mechanical characterisations have aided the understanding of how postsynthesis continual freezing or freeze-thaw manipulation affects network attributes.

  14. Mechanical properties of tough hydrogels synthesized with a facile simultaneous radiation polymerization and cross-linking method

    International Nuclear Information System (INIS)

    Radiation-induced polymerization and cross-linking method has been applied to hydrogel preparations for decades, but less attention has been paid to the mechanical properties of the hydrogels. In this work, we provide a systematic study on the mechanical properties of hydrogels synthesized with the simultaneous radiation polymerization and cross-linking method. The prepared polyacrylamide (PAAm) had very good mechanical properties, namely high compressive strengths (several to more than 10 MPa), high tensile strengths (up to 260 kPa), high fracture strains (up to 12) and high fracture energies (10–160 J/m2). Absorbed dose and monomer concentration were the two important factors affecting the mechanical properties of the gels. The compressive strength and elastic modulus of the gels increased with increasing absorbed dose and monomer concentration, while the tensile strength, fracture strain and fracture energy of the gels decreased with increasing absorbed dose. The gels also showed excellent elastic recovery property, as indicated by the low stress–strain hysteresis ratios in cyclic tensile tests as well as the small loss factors measured with dynamic mechanical analysis (DMA). - Highlights: • Polyacrylamide hydrogels are prepared by radiation polymerization method. • Systematic study on the mechanical properties of the gels is provided. • The gels show high compressive and tensile strengths. • The gels show high fracture energies and excellent elastic recovery property

  15. Poly(ethylene glycol) dicarboxylate/poly(ethylene oxide) hydrogel film co-crosslinked by electron beam irradiation as an anti-adhesion barrier.

    Science.gov (United States)

    Haryanto; Singh, Deepti; Han, Sung Soo; Son, Jun Hyuk; Kim, Seong Cheol

    2015-01-01

    The cross-linked poly(ethylene glycol) dicarboxylate (PEGDC)/poly(ethylene oxide) (PEO) and poly(ethylene glycol) dimethacrylate (PEGDMA)/(PEO) hydrogels were developed for possible biomedical applications such as an anti-adhesion barrier. Various contents of PEGDC/PEO film were irradiated using an electron beam with various beam intensities in order to obtain various degrees of crosslinked hydrogels. The optimum dose (300 kGy) and total crosslinker content of 10% were used to prepare crosslinked hydrogel films with three different compositions (10% PEGDC, 10% PEGDMA, 5% PEGDC-5% PEGDMA). Among them, 10% PEGDC hydrogel film exhibited the highest elongation at break (69.33±6.87%) with high mechanical strength. 10% PEGDC hydrogel film showed the lowest hemolysis activity (6.03±0.01%) and the highest tissue adherence (75.67±1.15 cN). The result also indicated that the carboxyl groups in PEGDC affect the tissue adherence of hydrogel films via H-bonding interactions. In animal studies, 10% PEGDC anti-adhesion hydrogel film degraded within 3 weeks and demonstrated better anti-adhesive effect compared to Guardix-SG®. PMID:25491977

  16. Novel enzymatically cross-linked hyaluronan hydrogels support the formation of 3D neuronal networks.

    Science.gov (United States)

    Broguiere, Nicolas; Isenmann, Luca; Zenobi-Wong, Marcy

    2016-08-01

    Hyaluronan (HA) is an essential component of the central nervous system's extracellular matrix and its high molecular weight (MW) form has anti-inflammatory and anti-fibrotic properties relevant for regenerative medicine. Here, we introduce a new hydrogel based on high MW HA which is cross-linked using the transglutaminase (TG) activity of the activated blood coagulation factor XIII (FXIIIa). These HA-TG gels have significant advantages for neural tissue engineering compared to previous HA gels. Due to their chemical inertness in the absence of FXIIIa, the material can be stored long-term, is stable in solution, and shows no cytotoxicity. The gelation is completely cell-friendly due to the specificity of the enzyme and the gelation rate can be tuned from seconds to hours at physiological pH and independently of stiffness. The gels are injectable, and attach covalently to fibrinogen and fibrin, two common bioactive components in in vitro tissue engineering, as well as proteins present in vivo, allowing the gels to covalently bind to brain or spinal cord defects. These optimal chemical and bioactive properties of HA-TG gels enabled the formation of 3D neuronal cultures of unprecedented performance, showing fast neurite outgrowth, axonal and dendritic speciation, strong synaptic connectivity in 3D networks, and rapidly-occurring and long-lasting coordinated electrical activity. PMID:27209262

  17. Fabrication and characterization of cross-linkable hydrogel particles based on hyaluronic acid: potential application in vocal fold regeneration.

    Science.gov (United States)

    Sahiner, Nurettin; Jha, Amit K; Nguyen, David; Jia, Xinqiao

    2008-01-01

    There is a critical need to engineer hyaluronic acid (HA)-based hydrogels with prolonged in vivo residence time, temporal release of therapeutics and matching viscoelasticity for use in vocal fold tissue engineering. We have previously demonstrated the synthesis and characterization of HA-based soft hydrogel particles (HGP) and particle cross-linked networks as injectable materials to treat vocal fold scarring. In this paper, we report a more versatile technique for preparing cross-linkable HA HGP with reduced sizes. HA HGP were synthesized via chemical cross-linking with divinyl sulfone using a sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelle system in the presence of 1-heptanol. These HGP were rendered cross-linkable by introducing aldehyde groups via sodium periodate oxidation (oxHGP). The presence of aldehyde groups was confirmed by multi-photon confocal microscope upon fluorescence staining using cascade blue hydrazide. The aldehyde groups were used as reactive handles for covalent cross-linking with HA that has been previously modified with adipic acid dihydrazide (HADH). The resulting doubly cross-linked networks (DXN) are highly pliable and do not break until approx. 200-300% strain. The measured elastic modulus of the DXN is around 500 Pa, while the dynamic viscosity decreases linearly with frequency in log- log scale. The mechanical characteristics of DXN are similar to that of vocal fold lamina propria. In vitro cell-proliferation assays showed that the cross-linkable HA HGP did not adversely affect the proliferation of the cultured fibroblasts as assessed by MTT assay. A low-molecular-weight model drug, rhodamine 6G (R6G), was loaded into oxHGP, and its release was monitored using UV-Vis spectroscopy. R6G-loaded oxHGP maintained their ability to form DXN when mixed with the HAADH solution. Approximately 84% of entrapped R6G was liberated from oxHGP at a rate of 0.24%/min in the first 6 h. When encapsulated in the DXN, R6G was

  18. Formation of model hepatocellular aggregates in a hydrogel scaffold using degradable genipin crosslinked gelatin microspheres as cell carriers

    International Nuclear Information System (INIS)

    Primary hepatocyte is probably the preferred cell for cell therapy in liver regeneration. However, its non-ideal proliferation capacity and rapid loss of phenotype during 2D culture compromises the quality and quantity of the transplanted hepatocytes, resulting in variable success rates of this treatment. Many studies have shown that the formation of 3D hepatocellular spheroids aids in the maintenance of liver-specific functions in hepatocytes. However, many of the methodologies employed require a sophisticated set-up or specialized equipment which makes it uneconomical to scale up for clinical applications. In this study, we have developed dual-functioning genipin crosslinked gelatin microspheres that serve as cell carriers as well as porogens for delivering the model cells and also for creating cavities. The cells were first seeded onto genipin crosslinked gelatin microspheres for attachment, followed by encapsulation in alginate hydrogel. Collagenase, MMP-9, was introduced either in the culture media or mixed with alginate precursor solution to allow microsphere degradation for creating cavities within the gel bulk. Accordingly, the cells proliferate within the cavities, forming hepatocellular aggregates while the alginate hydrogel serves as a confinement, restricting the size and the shape of the aggregates to the size of the cavities. In addition, the final hepatocellular aggregates could be harvested from the system by removing the alginate hydrogel via citrate treatment. Therefore, this versatile platform not only has the advantage of injectability and simplicity, the cellular aggregates generated are in a controlled size and shape and can be extracted from the system. (paper)

  19. Effect of different plasticizers on poly(N-vinyl-2-pyrrolidone) hydrogels cross-linked by radiation

    International Nuclear Information System (INIS)

    The use of hydrogel membranes usually demands polymers capable of forming films with high elastic and flexible properties besides having high water absorption. In terms of improvements of polymer plasticity, addition of special plasticizers to polymers can do it with promising results, although within limits of concentrations. The objective of this study was to evaluate the different effects of poly(enthylene glycol) (PEG) and glycerol as plasticizers on hydrogel membranes synthesized from poly(N-vinyl-2-pyrrolidone) (PVP) as the main polymer in aqueous polymeric solutions. For that, hydrogels of PVP/agar/PEG, PVP/agar/glycerol and without agar or plasticizer were simultaneously synthesized and sterilized by irradiation of mixtures of such products in aqueous solutions, using gamma-rays from 60Co source at a dose of 25 kGy. The results based on gel fraction, swelling in water, and some mechanical tests suggest that the degree of PVP cross-linking prevailed over the greater hydrophilicity of glycerol compared to that of PEG with regard to the degree of swelling of the hydrogels. (author)

  20. Effect of ethylene glycol dimethacrylate on swelling and on metformin hydrochloride release behavior of chemically crosslinked pH–sensitive acrylic acid–polyvinyl alcohol hydrogel

    OpenAIRE

    Akhtar, Muhammad Faheem; Ranjha, Nazar Muhammad; Hanif, Muhammad

    2015-01-01

    Background The present work objective was to prepare and to observe the effect of ethylene glycol dimethacrylate on swelling and on drug release behavior of pH-sensitive acrylic acid–polyvinyl alcohol hydrogel. Methods In the present work, pH sensitive acrylic acid–polyvinyl alcohol hydrogels have been prepared by free radical polymerization technique in the presence of benzoyl peroxide as an initiator. Different crosslinker contents were used to observe its effect on swelling and on drug rel...

  1. Study On Preparing Carboxymethyl Starch Hydrogel Radiation-Crosslinked On The Electron Beam Accelerator To Do The Moisturizing Material In Cosmetic

    International Nuclear Information System (INIS)

    Hydrogel of carboxymethyl starch (CMS) matrix was prepared by crosslinking of electron beam (EB) radiation on the EB linear accelerator UERL-10-15S2 (energy of 10 MeV, capacity of 15 kW, Russia) with support substances such as polyvinyl pyrrolidone (PVP), Kappa-Carragenan and Montmorillonit (MMT). The characteristic properties of hydrogel membrane such as gel content, degree of swelling, mechanical strength, adhesion force, water vapor transmission rate (WVTR) and skin allergy were experimented. This research will be firstly oriented in applications of CMS hydrogel material in cosmetic and personal care field such as facial mask for skin care, moisturizing membrane for skin and so on. (author)

  2. The characteristics of spontaneously forming physically cross-linked hydrogels composed of two water-soluble phospholipid polymers for oral drug delivery carrier I: hydrogel dissolution and insulin release under neutral pH condition.

    Science.gov (United States)

    Nam, Kwangwoo; Watanabe, Junji; Ishihara, Kazuhiko

    2004-11-01

    Hydrogels bearing a phospholipid polar group, 2-methacryloyloxyethyl phosphorylcholine (MPC), were prepared from two aqueous solutions of polymers, water-soluble poly[MPC-co-methacrylic acid (MA)] (PMA) and poly[MPC-co-n-butyl methacrylate (BMA)] (PMB). The hydrogel, which was formed by physical cross-linking spontaneously without any chemical reactions and/or any physical stimuli, showed a controllable insulin release through a pH change in the medium by changing the hydrogen bonds. In this study, the mechanical strength, erosion of the hydrogel caused by polymer dissociation, and the release of insulin were examined with attention to the following three parameters of the MPC polymer: molecular weight of the polymers, composition of PMA and PMB (PMA/PMB ratio), and polymer concentration inside the hydrogel. The hydrogel with the highest mechanical strength was obtained at a PMA/PMB ratio = 3/7 (v/v, by volume ratio) while the hydrogel with the slowest dissolution was obtained at a ratio of 5/5 (v/v). The release was in good match with the dissolution and followed anomalous transport for all, but the diffusion exponent n changed according to the PMA/PMB ratio. An increase in the polymer concentration inside the hydrogel caused an increase in the mechanical strength of the hydrogel. When the polymer concentration was more than 20 wt.%, the absorption of water under neutral pH condition (pH 6.8) was observed. The release of insulin was suppressed below 10% during the swelling process of the hydrogel under neutral pH condition, while release was accelerated during the erosion process of the hydrogel. The relationship between erosion of the hydrogel and the release of the insulin depended on the erosion process of the hydrogel but differed according to the PMA/PMB ratio. PMID:15489127

  3. A new injectable biphasic hydrogel based on partially hydrolyzed polyacrylamide and nano hydroxyapatite, crosslinked with chromium acetate, as scaffold for cartilage regeneration

    Science.gov (United States)

    Koushki, N.; Tavassoli, H.; Katbab, A. A.; Katbab, P.; Bonakdar, S.

    2015-05-01

    Polymer scaffolds are applied in the field of tissue engineering as three dimensional structures to organize cells and present stimuli to direct generation of a desired damaged tissue. In situ gelling scaffolds have attracted great attentions, as they are structurally similar to the extra cellular matrix (ECM). In the present work, attempts have been made to design and fabricate a new injectable and crosslinkable biphasic hydrogel based on partially hydrolyzed polyacrylamide (HPAM), chromium acetate as crosslink agent and nanocrystalline hydroxyapatite (nHAp) as reinforcing and bioactive agent for repair and regeneration of damaged cartilage. The distinct characteristic of HPAM is the presence of carboxylate anion groups on its backbone which allows to engineer the structure of the hydrogel for the desired bioactivity with appropriate cells differentiation towards both soft and hard (bone) tissues. The synthesized hydrogel exhibited bifunctional behavior which was derived by its biphasic structure in which one phase was loaded with nano hydroxyapatite to provide integration capability by subchondral bones and fix the hydrogel at cartilage defect without a need for suturing. The other phase differentiates the rabbit adipogenic mesenchymal stem cells (MSCs) towards soft tissue. Rheomechanical spectrometry (RMS) was employed to study the kinetic of the gelation including induction time and rate, as well as to measure the ultimate elastic modulus of the optimum crosslinked hydrogel. Surface tension measurement was also performed to tailor the surface characteristics of the gels. In vitro culturing of the cells inside the crosslinked hydrogel revealed high viability and high differentiation of the encapsulated rabbit stem cells, providing that the chromium acetate level was kept below 0.2 wt%. Based on the obtained results, the designed and fabricated biphasic hydrogel exhibited high potential as carrier for the stem cells for cartilage tissue engineering application

  4. Gamma radiation technology of producing crosslinked polymers (hydrogels) for specific application in medicine and biotechnology

    International Nuclear Information System (INIS)

    New polymeric hydrogels based on vinyl ethers have been synthesized by the γ-initiated polymerization method. Their physical chemistry and physical mechanical properties have been studied. It has been shown that structure and swelling behaviour of the hydrogels can be regulated by the changing of synthesis conditions and nature of monomers. Novel stimuli-sensitive polymers have been synthesized by the varying of macrochains hydrophilic-hydrophobic balance. The some biomedical aspects of application of hydrogels in capacity of drainaging polymeric materials in ophthalmology surgery, implants in plastic surgery as well as drug delivery systems. (author)

  5. Using pH-sensitive hydrogels containing cubane as a crosslinking agent for oral delivery of insulin.

    Science.gov (United States)

    Mahkam, Mehrdad

    2005-10-01

    The goal of oral insulin delivery devices is to protect the sensitive drug from proteolytic degradation in the stomach and upper portion of the small intestine. Copolymers of 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA) based hydrogels containing 2, 4, and 6% of a crosslinking agent (CA) were studied as drug delivery systems. Cubane-1, 4-dicarboxylic acid (CDA) was linked to two HEMA groups as CA. Radical copolymerizations of HEMA and MAA with the various ratios of CA were performed at 70 degrees C. The compositions of the crosslinked three-dimensional polymers were determined using Fourier transform infrared spectroscopy. Glass-transition temperature of the network polymers was determined calorimetrically. The effect of copolymer composition on the swelling behavior and hydrolytic degradation was studied in simulated gastric fluid (pH 1) and simulated intestinal fluid (pH 7.4). The swelling and hydrolytic behavior of the copolymers was dependent on the content of MAA groups and caused a decrease in gel swelling in simulated gastric fluid or an increase in gel swelling in simulated intestinal fluid. The drug-release profiles indicate that the amount of drug release depends on their degree of swelling and crosslinking. PMID:16025474

  6. Stimulus-responsiveness and methyl violet release behaviors of poly(NIPAAm-co-AA) hydrogels chemically crosslinked with β-cyclodextrin polymer bearing methacrylates.

    Science.gov (United States)

    Zhao, Hui; Gao, Jun; Liu, Ruina; Zhao, Sanping

    2016-06-16

    To fabricate thermo- and pH-sensitive hydrogels functionalized with β-cyclodextrin (β-CD) moieties, β-CD polymer bearing methacrylate (CDP-g-GMA) used as a reactive and functional crosslinker was synthesized, and then copolymerized with N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) in aqueous solution via UV-initiated free radical polymerization. The stimulus-responsiveness of the resultant hydrogels has been carried out by measuring the swelling ratio at different temperatures and pH values. The results showed that the thermo- and pH-sensitivities of the produced hydrogels were significantly dependent on the compositions of the hydrogels, and the dual sensitivities exhibited good reversible process. The interior morphology observed by SEM exhibited that the pore size of the hydrogels could be tailored by pH of the local medium. Using a water-soluble cationic dye methyl violet (MV) as a model drug, MV loading and release profiles of the hydrogels as potential drug controlled release carriers were evaluated. The MV release rate from CD-functionalized hydrogels was much slower than that from the hydrogel without β-CDs at both pH 2.0 and pH 7.4. The release of MV from CD-functionalized hydrogels at pH 2.0 was faster than that at pH 7.4, the release kinetics of MV from the CD-functionalized hydrogels displayed a sustained release profile, and the release mechanism followed Fickian diffusion. PMID:27152631

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

    Science.gov (United States)

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

    2016-01-01

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

  8. Composite vascular scaffold combining electrospun fibers and physically-crosslinked hydrogel with copper wire-induced grooves structure.

    Science.gov (United States)

    Liu, Yuanyuan; Jiang, Chen; Li, Shuai; Hu, Qingxi

    2016-08-01

    While the field of tissue engineered vascular grafts has greatly advanced, many inadequacies still exist. Successfully developed scaffolds require mechanical and structural properties that match native vessels and optimal microenvironments that foster cell integration, adhesion and growth. We have developed a small diameter, three-layered composite vascular scaffold which consists of electrospun fibers and physically-crosslinked hydrogel with copper wire-induced grooves by combining the electrospinning and dip-coating methods. Scaffold morphology and mechanics were assessed, quantified and compared to native vessels. Scaffolds were seeded with Human Umbilical Vein Endothelial Cells (HUVECs), cultured in vitro for 3 days and were evaluated for cell viability and morphology. The results showed that composite scaffolds had adjustable mechanical strength and favorable biocompatibility, which is important in the future clinical application of Tissue-engineered vascular grafts (TEVGs). PMID:26820993

  9. Mechanical and structural response of a hybrid hydrogel based on chitosan and poly(vinyl alcohol) cross-linked with epichlorohydrin for potential use in tissue engineering.

    Science.gov (United States)

    Garnica-Palafox, I M; Sánchez-Arévalo, F M; Velasquillo, C; García-Carvajal, Z Y; García-López, J; Ortega-Sánchez, C; Ibarra, C; Luna-Bárcenas, G; Solís-Arrieta, L

    2014-01-01

    The development and characterization of a hybrid hydrogel based on chitosan (CS) and poly(vinyl alcohol) (PVA) chemically cross-linked with epichlorohydrin (ECH) is presented. The mechanical response of these hydrogels was evaluated by uniaxial tensile tests; in addition, their structural properties such as average molecular weight between cross-link points (Mcrl), mesh size (DN), and volume fraction (v(s)) were determined. This was done using the equivalent polymer network theory in combination with the obtained results from tensile and swelling tests. The films showed Young's modulus values of 11 ± 2 MPa and 9 ± 1 MPa for none irradiated and ultraviolet (UV) irradiated hydrogels, respectively. The cell viability was assessed using Calcein AM and Ethidium homodimer-1 assay and environmental scanning electron microscopy. The 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan thiazolyl blue formazan (MTT Formazan assay) results did not show cytotoxic effects; this was in good agreement with nuclear magnetic resonance and fourier transform infrared spectroscopies; their results did not show traces of ECH. This indicated that after the crosslinking process, there was no free ECH; furthermore, any possibility of ECH release in the construct during cell culture was discarded. The CS-PVA-ECH hybrid hydrogel allowed cell growth and extracellular matrix formation and showed adequate mechanical, structural, and biological properties for potential use in tissue engineering applications. PMID:24007370

  10. Photo-activated ionic gelation of alginate hydrogel: real-time rheological monitoring of the two-step crosslinking mechanism.

    Science.gov (United States)

    Higham, Alina K; Bonino, Christopher A; Raghavan, Srinivasa R; Khan, Saad A

    2014-07-21

    We examine the gelation of alginate undergoing ionic crosslinking upon ultraviolet (UV) irradiation using in situ dynamic rheology. Hydrogels are formed by combining alginate with calcium carbonate (CaCO3) particles and a photoacid generator (PAG). The PAG is photolyzed upon UV irradiation, resulting in the release of free calcium ions for ionic crosslinking. The viscous and elastic moduli during gelation are monitored as a function of the UV irradiation intensity, exposure time, alginate concentration, and the ratio between alginate and calcium carbonate. Gel time decreases as irradiation intensity increases because a larger concentration of PAG is photolyzed. Interestingly, dark curing, the continuing growth of microstructure in the absence of UV light, is observed. In some instances, the sample transitions from a solution to a gel during the dark curing phase. Additionally, when exposed to constant UV irradiation after the dark curing phase, samples reach the same plateau modulus as samples exposed to constant UV without dark curing, implying that dark curing does not affect the gelation mechanism. We believe the presence of dark curing is the result of the acidic environment persisting within the sample, allowing CaCO3 to dissociate, thereby releasing free Ca(2+) ions capable of binding with the available appropriate ionic blocks of the polymer chains. The growth of microstructure is then detected if the activation barrier has been crossed to release sufficient calcium ions. In this regard, we calculate a value of 30 J that represents the activation energy required to initiate gelation. PMID:24894636

  11. Fabrication of tubular tissue constructs by centrifugal casting of cells suspended in an in situ crosslinkable hyaluronan-gelatin hydrogel.

    Science.gov (United States)

    Mironov, Vladimir; Kasyanov, Vladimir; Zheng Shu, Xiao; Eisenberg, Carol; Eisenberg, Leonard; Gonda, Steve; Trusk, Thomas; Markwald, Roger R; Prestwich, Glenn D

    2005-12-01

    Achieving the optimal cell density and desired cell distribution in scaffolds is a major goal of cell seeding technologies in tissue engineering. In order to reach this goal, a novel centrifugal casting technology was developed using in situ crosslinkable hyaluronan-based (HA) synthetic extracellular matrix (sECM). Living cells were suspended in a viscous solution of thiol-modified HA and thiol-modified gelatin, a polyethyleneglycol diacrylate crosslinker was added, and a hydrogel was formed during rotation. The tubular tissue constructs consisting of a densely packed cell layer were fabricated with the rotation device operating at 2000 rpm for 10 min. The majority of cells suspended in the HA mixture before rotation were located inside the layer after centrifugal casting. Cells survived the effect of the centrifugal forces experienced under the rotational regime employed. The volume cell density (65.6%) approached the maximal possible volume density based on theoretical sphere packing models. Thus, centrifugal casting allows the fabrication of tubular constructs with the desired redistribution, composition and thickness of cell layers that makes the maximum efficient use of available cells. Centrifugal casting in this sECM would enable rapid fabrication of tissue-engineered vascular grafts, as well as other tubular and planar tissue-engineered constructs. PMID:16023201

  12. Robust Self-Healing Hydrogels Assisted by Cross-Linked Nanofiber Networks

    OpenAIRE

    Yuan Fang; Cai-Feng Wang; Zhi-Hong Zhang; Huan Shao; Su Chen

    2013-01-01

    Given increasing environmental and energy issues, mimicking nature to confer synthetic materials with self-healing property to expand their lifespan is highly desirable. Just like human skin recovers itself upon damage with the aid of nutrient-laden blood vascularization, designing smart materials with microvascular network to accelerate self-healing is workable but continues to be a challenge. Here we report a new strategy to prepare robust self-healing hydrogels assisted by a healing layer ...

  13. Preparation and Mechanical Properties of Photo-Crosslinked Fish Gelatin/Imogolite Nanofiber Composite Hydrogel

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Shibata

    2012-11-01

    Full Text Available Fish gelatin (FG extracted from sea bream scales was reacted with glycidyl methacrylate (GMA, and the product (FG-GMA was used for photopolymerization using a radical photoinitiator in the presence or absence of imogolite nanofibers in the aqueous solution. The synthesis of FG-GMA was confirmed by 1H NMR spectroscopy, and photopolymerization of FG-GMA was achieved successfully by irradiation with ultraviolet (UV light for 3 min to yield translucent composite hydrogels. The concentration of FG-GMA varied from 10% to 30% without imogolite, and that of imogolite varied from 0% to 2.0%. A microtomed gel sample was observed with a transmission electron microscope (TEM, and imogolite nanofibers were found to be dispersed finely in the gelatin matrix. Scanning electron microscope (SEM observation of the lyophilized gel revealed that it had a porous morphology. Mechanical properties of hydrogels were measured by compression tests using a mechanical tester, and viscoelastic properties were measured using a rheometer. The mechanical strength and storage modulus of the hydrogel increased with an increase of imogolite.

  14. In vitro degradation of covalently cross-linked arabinoxylan hydrogels by bifidobacteria.

    Science.gov (United States)

    Martínez-López, Ana L; Carvajal-Millan, Elizabeth; Micard, Valérie; Rascón-Chu, Agustín; Brown-Bojorquez, Francisco; Sotelo-Cruz, Norberto; López-Franco, Yolanda L; Lizardi-Mendoza, Jaime

    2016-06-25

    Arabinoxylan gels with different cross-linking densities, swelling ratios, and rheological properties were obtained by increasing the concentration of arabinoxylan from 4 to 6% (w/v) during oxidative gelation by laccase. The degradation of these covalently cross-linked gels by a mixture of two Bifidobacterium strains (Bifidobacterium longum and Bifidobacterium adolescentis) was investigated. The kinetics of the evolution of structural morphology of the arabinoxylan gel, the carbohydrate utilization profiles and the bacterial production of short-acid fatty acid (SCFA) were measured. Scanning electron microscopy analysis of the degraded gels showed multiple cavity structures resulting from the bacterial action. The total SCFA decreased when the degree of cross-linking increased in the gels. A slower fermentation of arabinoxylan chains was obtained for arabinoxylan gels with more dense network structures. These results suggest that the differences in the structural features and properties studied in this work affect the degradation time of the arabinoxylan gels. PMID:27083795

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

    Science.gov (United States)

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

    2015-05-01

    An injectable hybrid hydrogel system was developed consisting of hyaluronic acid (HA) crosslinked by well-defined block copolymers of the cationic poly(2-aminoethyl methacrylate) (PAEM) and polyethylene glycol (PEG). Robust, shear-thinning hybrid hydrogel was produced by mixing HA and 4-arm star PEG-PAEM block copolymer at 1:1 charge ratio. The encapsulation and release of highly viable human mesenchymal stem cells in physiological media was demonstrated. After subcutaneous injection of the hybrid gel in mice, mild but resolvable inflammatory response was observed. This hybrid gel could serve as a model system for studying structure-function relationship of polyelectrolyte hydrogels and as a practical injectable biomaterial for medical applications. PMID:25630277

  16. 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.

  17. Radiation technology in designing cross-linked hydrogels for biomedical applications

    International Nuclear Information System (INIS)

    Radiation technology has emerging as an environment friendly commercially viable technology with broad applications that can essentially contribute to achieve the goal of sustainable development. This technology is based on the use of ionizing radiation to modify the structure and properties of materials in different industrial applications particularly in heath care, polymer and environmental applications. In the field of material science, radiation technology produces the high performance polymeric materials with unique physical and chemical properties. The present work reports biomedical applications of radiation processed hydrogels. (author)

  18. Hydrogels Constructed from Engineered Proteins.

    Science.gov (United States)

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

    2016-02-24

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

  19. Cross-linking oxidized cellulose nanofibrils for the formation of stable hydrogel structures

    OpenAIRE

    Pettersen, Sigurd Rolland

    2013-01-01

    The main goal of this project was to investigate whether the elastic properties of microfibrillated cellulose (MFC) suspensions pre-treated by TEMPO-mediated oxidation could be controlled by inducing cross-links between the nanofibrils with short diamines. Using conductometric titration, the total carboxylate and aldehyde content in the MFC was measured as 0.810 mmol/g MFC and 0.181 mmol/g MFC, respectively.The viscoelastic properties of the MFC were investigated by dynamic measurements. The ...

  20. Preparation and characterization of polyvinyl alcohol hydrogels crosslinked by biodegradable polyurethane for tissue engineering of cartilage

    Energy Technology Data Exchange (ETDEWEB)

    Bonakdar, Shahin [Biomedical Engineering Department, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Emami, Shahriar Hojjati, E-mail: shahriar16@yahoo.com [Biomedical Engineering Department, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, 13164 (Iran, Islamic Republic of); Farhadi, Afshin [Tehran Azad University of Medical Science, Amiralmomenin Hospital (Iran, Islamic Republic of); Ahmadi, Seyed Amir Hoshiar [Biomedical Engineering Department, Amirkabir University of Technology, Tehran, 15875-4413 (Iran, Islamic Republic of); Amanzadeh, Amir [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran, 13164 (Iran, Islamic Republic of)

    2010-05-10

    Polyurethane was prepared from hexamethylene diisocyanate (HMDI) and polycaprolactone diol (PCL) with stoichiometry ratio of two in a reactor to form prepolymer. Polyvinyl alcohol (PVA) at PVA/prepolymer ratios of 8, 4, 2 and 1 was crosslinked with the former degradable polyester polyurethane. Fourier transform infrared (FTIR) was employed to confirm polyurethane formation during the course of reactions. FTIR spectrum revealed bands at 1729-1733 cm{sup -1} and 3347-3340 cm{sup -1} which indicates carbonyl and NH of amine groups, respectively. Polyurethane formation was also confirmed by the absence of the isocyanate peaks (NCO) at 2270 cm{sup -1}. Dynamic mechanical thermal analysis (DMTA) showed that by increasing prepolymer concentration glass transition temperature decreases from 26 deg. C for PVA to 19 deg. C for sample with PVA/prepolymer ratio of 4 and then it rises up to 31 deg. C. Water uptake measurements illustrated about four fold reduction in swelling ratio of PVA after crosslinking and the sample with equal amounts of PVA and PPU had water uptake of 100%, close to that of a natural cartilage and much less than PVA (425%). All samples had compressive modulus in the range of the articular cartilage (1.9-14.4 MPa). The morphology of the isolated cells on the samples was evaluated by scanning electron microscopy (SEM) and revealed cell attachment and proliferation. The cell viability (3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) and GAG expression (dimethylmethylene blue, DMMB) assays with human chondrocytes on the sample with PVA/prepolymer ratio of one showed about 14 and 33% increase in cell viability and GAG expression after 14 days of culture compare to the PVA, respectively.

  1. Preparation and characterization of polyvinyl alcohol hydrogels crosslinked by biodegradable polyurethane for tissue engineering of cartilage

    International Nuclear Information System (INIS)

    Polyurethane was prepared from hexamethylene diisocyanate (HMDI) and polycaprolactone diol (PCL) with stoichiometry ratio of two in a reactor to form prepolymer. Polyvinyl alcohol (PVA) at PVA/prepolymer ratios of 8, 4, 2 and 1 was crosslinked with the former degradable polyester polyurethane. Fourier transform infrared (FTIR) was employed to confirm polyurethane formation during the course of reactions. FTIR spectrum revealed bands at 1729-1733 cm-1 and 3347-3340 cm-1 which indicates carbonyl and NH of amine groups, respectively. Polyurethane formation was also confirmed by the absence of the isocyanate peaks (NCO) at 2270 cm-1. Dynamic mechanical thermal analysis (DMTA) showed that by increasing prepolymer concentration glass transition temperature decreases from 26 deg. C for PVA to 19 deg. C for sample with PVA/prepolymer ratio of 4 and then it rises up to 31 deg. C. Water uptake measurements illustrated about four fold reduction in swelling ratio of PVA after crosslinking and the sample with equal amounts of PVA and PPU had water uptake of 100%, close to that of a natural cartilage and much less than PVA (425%). All samples had compressive modulus in the range of the articular cartilage (1.9-14.4 MPa). The morphology of the isolated cells on the samples was evaluated by scanning electron microscopy (SEM) and revealed cell attachment and proliferation. The cell viability (3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) and GAG expression (dimethylmethylene blue, DMMB) assays with human chondrocytes on the sample with PVA/prepolymer ratio of one showed about 14 and 33% increase in cell viability and GAG expression after 14 days of culture compare to the PVA, respectively.

  2. The impact of hyaluronic acid oligomer content on physical, mechanical, and biologic properties of divinyl sulfone-crosslinked hyaluronic acid hydrogels.

    Science.gov (United States)

    Ibrahim, Samir; Kang, Qian K; Ramamurthi, Anand

    2010-08-01

    In recent studies, we showed that exogenous hyaluronic acid oligomers (HA-o) stimulate functional endothelialization, though native long-chain HA is more bioinert and possibly more biocompatible. Thus, in this study, hydrogels containing high molecular weight (HMW) HA (1 x 10(6) Da) and HA-o mixtures (HA-o: 0.75-10 kDa) were created by crosslinking with divinyl sulfone (DVS). The incorporation of HA-o was found to compromise the physical and mechanical properties of the gels (rheology, apparent crosslinking density, swelling ratio, degradation) and to very mildly enhance inflammatory cell recruitment in vivo; increasing the DVS crosslinker content within the gels in general, had the opposite effect, though the relatively high concentration of DVS within these gels (necessary to create a solid gel) also stimulated a mild subcutaneous inflammatory response in vivo and VCAM-1 expression by endothelial cells (ECs) cultured atop; ICAM-expression levels remained very low irrespective extent of DVS crosslinking or HA-o content. The greatest EC attachment and proliferation (MTT assay) was observed on gels that contained the highest amount of HA-o. The study shows that the beneficial EC response to HA-o and biocompatibility of HA is mostly unaltered by their chemical derivatization and crosslinking into a hydrogel. However, the study also demonstrates that the relatively high concentrations of DVS, necessary to create solid gels, compromise their biocompatibility. Moreover, the poor mechanics of even these heavily crosslinked gels, in the context of vascular implantation, necessitates the investigation of other, more appropriate crosslinking agents. Alternately, the outcomes of this study may be used to guide an approach based on chemical immobilization and controlled surface-presentation of both bioactive HA-o and more biocompatible HMW HA on synthetic or tissue engineered grafts already in use, without the use of a crosslinker, so that improved, predictable, and

  3. Radiation cross-linked carboxymethyl sago pulp hydrogels loaded with ciprofloxacin: Influence of irradiation on gel fraction, entrapped drug and in vitro release

    International Nuclear Information System (INIS)

    Carboxymethyl sago pulp (CMSP) with 0.4 DS, viscosity 184 dl/g and molecular weight 76,000 g/mol was synthesized from sago waste. 10 and 20% w/v solutions of CMSP were irradiated at 10–30 kGy to form hydrogels and were characterized by % gel fraction (GF). Irradiation of 20% CMSP using 25 kGy has produced stable hydrogels with the highest % GF and hence loaded with ciprofloxacin HCl. Drug-loaded hydrogels were produced by irradiating the mixture of drug and 20% CMSP solution at 25 kGy. After irradiation, the hydrogels were cut into circular discs with a diameter of 6±1 mm and evaluated for physicochemical properties as well as drug release kinetics. The ciprofloxacin loading in the disc was 14.7%±1 w/w with an entrapment efficiency of 73.5% w/w. The low standard deviation of drug-loaded discs indicated uniform thickness (1.5±0.3 mm). The unloaded discs were thinner (1±0.4 mm) and more brittle than the drug-loaded discs. FESEM, FT-IR, XRD, DSC and TGA analysis revealed the absence of polymer–drug interaction and transformation of crystalline to amorphous form of ciprofloxacin in the discs. The disc sustained the drug release in phosphate buffer pH 7.4 over 36 h in a first-order manner. The mechanism of the drug release was found to be swelling controlled diffusion and matrix erosion. The anti-bacterial effect of ciprofloxacin was retained after irradiation and CMSP disc could be a promising device for ocular drug delivery. - Highlights: • Carboxymethyl sago pulp (CMSP) with ciprofloxacin is irradiated to form hydrogels. • 20% CMSP at 25 kGy has produced stable hydrogels with the highest gel fraction. • Crystalline ciprofloxacin converted as amorphous during hydrogel formation. • Hydrogel in disc form sustained the drug release drug up to 36 h. • Irradiation cross-linked polymeric chain of CMSP resulted in controlled swelling

  4. The prevention of peritoneal adhesions by in-situ cross-linking hydrogels of hyaluronic acid and cellulose derivatives

    OpenAIRE

    Ito, Taichi; Yeo, Yoon; Highley, Christopher B.; Bellas, Evangelia; Benitez, Carlos A; Kohane, Daniel S.

    2006-01-01

    Postoperative peritoneal adhesions can cause pelvic pain, infertility, and potentially lethal bowel obstruction. We have designed and synthesized injectable hydrogels that are formed by mixing hydrazide-modified hyaluronic acid (HA) with aldehyde-modified versions of cellulose derivatives such as carboxymethylcellulose (CMC), hydroxypropylmethyl cellulose (HPMC), and methyl cellulose (MC). Gelation of these hydrogels occurred in less than 1 min, and had higher shear moduli than that of HA-HA ...

  5. Supramolecular hydrogels formed from poly(viologen cross-linked with cyclodextrin dimers and their physical properties

    Directory of Open Access Journals (Sweden)

    Yoshinori Takashima

    2012-09-01

    Full Text Available Supramolecular materials with noncovalent bonds have attracted much attention due to their exclusive properties differentiating them from materials formed solely by covalent bonds. Especially interesting are rotor molecules of topological complexes that shuttle along a polymer chain. The shuttling of these molecules should greatly improve the tension strength. Our research employs cyclodextrin (CD as a host molecule, because CD effectively forms polyrotaxanes with polymers. Herein we report the formation of supramolecular hydrogels with an α-CD dimer (α,α-CD dimer as a topological linker molecule, and a viologen polymer (VP as the polymer chain. The supramolecular hydrogel of α,α-CD dimer/VP forms a self-standing gel, which does not relax (G' > G'' in the frequency range 0.01–10 rad·s−1. On the other hand, the supramolecular hydrogel decomposes upon addition of bispyridyl decamethylene (PyC10Py as a competitive guest. Moreover, the β-CD dimer (β,β-CD dimer with VP does not form a supramolecular hydrogel, indicating that complexation between the C10 unit of VP and the α-CD unit of the α,α-CD dimer plays an important role in the formation of supramolecular hydrogels.

  6. 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

    International Nuclear Information System (INIS)

    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)

  7. Highly porous nanocomposite poly(N-isopropylacrylamide) hydrogels with fast temperature response: effect of crosslinker and silica filler amount

    Czech Academy of Sciences Publication Activity Database

    Strachota, Beata

    Novi Sad : Faculty of Technology, University of Novi Sad, 2011 - (Maca, K.; Trunec, M.). s. 43 [Final Workshop of FP7 REGPOT-2007-3 DEMATEN "Processing of Nanostructured Ceramics and Nanocomposites". 03.03.2011-05.03.2011, Brno] R&D Projects: GA AV ČR IAA400500701 EU Projects: European Commission(XE) 204953 - RP-DEMATEN Institutional research plan: CEZ:AV0Z40500505 Keywords : poly N-isopropylacrylamide * sol- gel process * porous hydrogels Subject RIV: CD - Macromolecular Chemistry

  8. Rapid self-healing hydrogels

    OpenAIRE

    Phadke, Ameya; Zhang, Chao; Arman, Bedri; Hsu, Cheng-Chih; Mashelkar, Raghunath A.; Lele, Ashish K.; Tauber, Michael J.; Arya, Gaurav; Varghese, Shyni

    2012-01-01

    Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hyd...

  9. Cross-Linked Hydrogels Formed through Diels-Alder Coupling of Furan- and Maleimide-Modified Poly(methyl vinyl ether-alt-maleic acid).

    Science.gov (United States)

    Stewart, S Alison; Backholm, Matilda; Burke, Nicholas A D; Stöver, Harald D H

    2016-02-23

    The Diels-Alder [4 + 2] cycloaddition between furan- and maleimide-functional polyanions was used to form cross-linked synthetic polymer hydrogels. Poly(methyl vinyl ether-alt-maleic anhydride) was reacted with furfurylamine or N-(2-aminoethyl)maleimide in acetonitrile to form pairs of furan- and maleimide-functionalized poly(methyl vinyl ether-alt-maleic acid)s. Mixtures of these mutually reactive polyanions in water gelled within 15 min to 18 h, depending on degree of functionalization and polymer concentrations. Solution and magic-angle spinning (1)H NMR were used to confirm the formation of the Diels-Alder adduct, to analyze competing hydrolytic side reactions, and demonstrate postgelation functionalization. The effect of the degree of furan and maleimide functionalization, polymer concentration, pH, and calcium ion concentration, on gelation time, gel mechanical properties, and equilibrium swelling, are described. Release of dextran as a model drug was studied using fluorescence spectroscopy, as a function of gel composition and calcium treatment. PMID:26800849

  10. Studies of the stability of water-soluble polypeptoid helices and investigation of synthetic, biomimetic substrates for the development of a thermally triggered, enzymatically crosslinked hydrogel for biomedical applications

    Science.gov (United States)

    Sanborn, Tracy Joella

    Due to the unique 3D structures of proteins, these biopolymers are able to perform a myriad of vital functions and activities in vivo. Peptidomimetic oligomers are being synthesized to mimic the structure and function of natural peptides. We have examined the stability of secondary structure of a poly-N-substituted glycine (peptoid) and developed synthetic substrates for transglutaminase enzymes. We synthesized an amphipathic, helical, 36 residue peptoid to study the stability of peptoid secondary structure using circular dichroism. We saw no significant dependence of helical structure on concentration, solvent, or temperature. The extraordinary resistance of these peptoid helices to denaturation is consistent with a dominant role, of steric forces in their structural stabilization. The structured polypeptoids studied here have potential as robust mimics of helical polypeptides of therapeutic interest. The ability of transglutaminases to crosslink peptidomimetic substrates was also investigated. There is a medical need for robust, biocompatible hydrogels that can be rapidly crosslinked in situ, for application as surgical adhesives, bone-inductive materials, or for drug delivery. We have taken an enzymatic approach to the creation of a novel gelation system that fits these requirements, utilizing transglutaminase enzymes, thermo-responsive liposomes, and a biomimetic enzyme substrate based on a peptide-polymer conjugate. At room temperature, the hydrogel system is a solution. Upon heating to 37°C, the calcium-loaded liposomes release calcium that activates Factor XIII in the presence of thrombin, producing a gel within 9 minutes. Rheological studies demonstrated that the hydrogel behaves as a robust, elastic solid, while scanning electron microscopy studies revealed that the hydrogel has a very dense morphology overall. We also investigated the ability of transglutaminases to crosslink non-natural, peptoid-based substrates. The activity of five lysine

  11. Cytocompatible Poly(ethylene glycol)-co-polycarbonate Hydrogels Crosslinked by Copper-free, Strain-promoted “Click” Chemistry

    OpenAIRE

    Xu, Jianwen; Filion, Tera M.; Prifti, Fioleda; Song, Jie

    2011-01-01

    Strategies to encapsulate cells in cytocompatible 3-dimensional hydrogels with tunable mechanical properties and degradability without harmful gelling conditions are highly desired for regenerative medicine applications. Here we reported a method for preparing poly(ethylene glycol)-co-polycarbonate hydrogels through copper-free, strain-promoted azide-alkyne cycloaddition (SPAAC) “Click” chemistry. Hydrogels with varying mechanical properties were formed by “clicking” azido-functionalized poly...

  12. Radiation processing of sago hydrogel thin film

    International Nuclear Information System (INIS)

    Research study in the production of sago hydrogel sheet for wound dressings application by radiation process using high-energy electron beam machine (3 MeV) has been well established at MINT. However, producing thin film sago hydrogel is another potential usage of this sago hydrogel. The research activity is to look upon the possibility of utilize low-energy electron beam, Curetron (200 keV) for this purpose. The studies are concentrate on the radiation parameters such as beam current, voltage and dosage, thickness of sago hydrogel and density of polyvinyl alcohol solution for comparison purpose. The studies reveal that crosslinking of sago hydrogel depend on thickness of the material exposed to electron beam i.e. thin sample gives higher degree of crosslink compared to thicker sample, at specific dosage and beam current. Above 0.5 mm thickness, the sago hydrogel cannot be crosslinked by low energy electron beam. The results also show that for Curetron 8 mA is the optimum beam current for effective crosslinking process of sago hydrogel. The penetration of electron beam by Curetron depends on density, based on the gel fraction of PVA crosslink where 20% PVA has higher gel fraction than 25% PVA at specific dosage and thickness of sample. From the study using high-energy electron beam machine (3 MeV), the degree of crosslink reduced with increasing thickness of sago hydrogel for the voltage less than 0.75 MeV. (author)

  13. 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

    2016-01-01

    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

  14. 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

  15. 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

  16. Synthesis and Characterization of Phosphated Konjac Glucomannan Hydrogels

    Institute of Scientific and Technical Information of China (English)

    Li Gui CHEN; Zhi Lan LIU; Ying Jun CHEN; Ren Xi ZHUO

    2005-01-01

    Konjac glucomannan (KGM) was crosslinked with sodium tripolyphosphate (STPP) to synthesize hydrogels. The crosslinking reaction was confirmed by FT-IR. The results of degradation test show that the hydrogels retain the enzymatic degradation character of KGM and can be degraded for 74.45% in 5 days by cellulase E0240.

  17. Synthetically simple, highly resilient hydrogels.

    Science.gov (United States)

    Cui, Jun; Lackey, Melissa A; Madkour, Ahmad E; Saffer, Erika M; Griffin, David M; Bhatia, Surita R; Crosby, Alfred J; Tew, Gregory N

    2012-03-12

    Highly resilient synthetic hydrogels were synthesized by using the efficient thiol-norbornene chemistry to cross-link hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) polymer chains. The swelling and mechanical properties of the hydrogels were controlled by the relative amounts of PEG and PDMS. The fracture toughness (G(c)) was increased to 80 J/m(2) as the water content of the hydrogel decreased from 95% to 82%. In addition, the mechanical energy storage efficiency (resilience) was more than 97% at strains up to 300%. This is comparable with one of the most resilient materials known: natural resilin, an elastic protein found in many insects, such as in the tendons of fleas and the wings of dragonflies. The high resilience of these hydrogels can be attributed to the well-defined network structure provided by the versatile chemistry, low cross-link density, and lack of secondary structure in the polymer chains. PMID:22372639

  18. Radiation synthesis and characterization of polyacrylic acid hydrogels

    Institute of Scientific and Technical Information of China (English)

    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.

  19. Synthetically Simple, Highly Resilient Hydrogels

    OpenAIRE

    Cui, Jun; Lackey, Melissa A.; Madkour, Ahmad E.; Saffer, Erika M.; Griffin, David M.; Bhatia, Surita R.; Crosby, Alfred J.; Tew, Gregory N.

    2012-01-01

    Highly resilient synthetic hydrogels were synthesized by using the efficient thiol-norbornene chemistry to cross-link hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) polymer chains. The swelling and mechanical properties of the hydrogels were well-controlled by the relative amounts of PEG and PDMS. In addition, the mechanical energy storage efficiency (resilience) was more than 97% at strains up to 300%. This is comparable with one of the most resilient mat...

  20. Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications

    OpenAIRE

    2015-01-01

    Hyaluronic acid (HA) hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS) based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injec...

  1. Rheological studies of thermosensitive triblock copolymer hydrogels

    NARCIS (Netherlands)

    Vermonden, T.; Besseling, N.A.M.; Steenbergen, van M.J.; Hennink, W.E.

    2006-01-01

    Hydrogel formation by physical cross-linking is a developing area of research toward materials suitable for pharmaceutical and biomedical applications. Polymers exhibiting lower critical solution temperature (LCST) behavior in aqueous solution are used in this study to prepare hydrogels. Four triblo

  2. Radiation processing of cassava starch hydrogel

    International Nuclear Information System (INIS)

    This paper consists of two topics on cassava starch (CS). The first paper deals with radiation-induced graft polymerization of 1-vinyl-2-pyrrolidinone (VP) onto CS. 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%, could be prepared at the dose of 20 kGy, while PVP and PVP-blended-starch hydrogels require at least 30 kGy to obtain gels with more than 80% gel fraction. And at the same dose used for irradiation, the gel strength of the PVP-grafted-starch hydrogels is significantly higher than that of the PVP and PVP-blended-starch hydrogels. Radiation crosslinking of carboxymethyl CS is the second topic. CS was chemically modified by sodium monochloroacetate (SMCA) to yield carboxymethyl starch (CMS). The aqueous solution of CMS was irradiated and underwent radiation-induced crosslinking, resulting in a crosslinked CMS (XLCMS) hydrogel. The optimum condition for obtaining hydrogels with desirable properties is irradiation at low dose, 2 kGy. At higher doses, the gel fraction tends to diminish, due to the domination of degradation over crosslinking. (author)

  3. Flexible hydrogel-based functional composite materials

    Science.gov (United States)

    Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R; Tomasia, Antoni P

    2013-10-08

    A composite having a flexible hydrogel polymer formed by mixing an organic phase with an inorganic composition, the organic phase selected from the group consisting of a hydrogel monomer, a crosslinker, a radical initiator, and/or a solvent. A polymerization mixture is formed and polymerized into a desired shape and size.

  4. Hydrogel wound dressing by radiation

    International Nuclear Information System (INIS)

    Water soluble polymers such as polyethyleneoxide (PEO), polyvinyl alcohol (PVA) were irradiated in solid and molten states as well as in aqueous solution in order to synthesize a hydrogel. PEO undergoes crosslinking at all phases by radiation initiation. Among these phases, the radiation in the aqueous solution requires the lowest dose for crosslinking due to the contribution of OH radical created in radiolysis of water. The hydrogel prepared by irradiation in aqueous solution was applied to a dressing for healing of wound. In order to evaluate the healing effect of the PEO hydrogel dressing, wounds formed on the back of marmots were covered by the hydrogel. The healing under the wet environment of the hydrogel dressing had three advantages, compared with that of gauze dressing, which gives a dry environment: (1) enhancement of healing rate, (2) facilitation for changing the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated skin surface, and (3) hydrogel dressing material does not remain stuck on the wound. (author)

  5. Hydrogel wound dressing by radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yoshii, Fumio [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2002-03-01

    Water soluble polymers such as polyethyleneoxide (PEO), polyvinyl alcohol (PVA) were irradiated in solid and molten states as well as in aqueous solution in order to synthesize a hydrogel. PEO undergoes crosslinking at all phases by radiation initiation. Among these phases, the radiation in the aqueous solution requires the lowest dose for crosslinking due to the contribution of OH radical created in radiolysis of water. The hydrogel prepared by irradiation in aqueous solution was applied to a dressing for healing of wound. In order to evaluate the healing effect of the PEO hydrogel dressing, wounds formed on the back of marmots were covered by the hydrogel. The healing under the wet environment of the hydrogel dressing had three advantages, compared with that of gauze dressing, which gives a dry environment: (1) enhancement of healing rate, (2) facilitation for changing the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated skin surface, and (3) hydrogel dressing material does not remain stuck on the wound. (author)

  6. Morphological effect on swelling behaviour of hydrogel

    Science.gov (United States)

    Yacob, Norzita; Hashim, Kamaruddin

    2014-02-01

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

  7. Morphological effect on swelling behaviour of hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Yacob, Norzita; Hashim, Kamaruddin [Radiation Processing Technology Division, Malaysian Nuclear Agency (NUKLEAR MALAYSIA) Bangi, 43000 Kajang (Malaysia)

    2014-02-12

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

  8. Effects of chain flexibility on the properties of DNA hydrogels.

    Science.gov (United States)

    Pan, Wei; Wen, Hao; Niu, Lin; Su, Cuicui; Liu, Chenyang; Zhao, Jiang; Mao, Chengde; Liang, Dehai

    2016-07-01

    The effect of chain rigidity on the mechanic properties of DNA hydrogels was studied. Counterintuitively, the hydrogel formed by mainly flexible chains exhibited better stability, stretchability, and much mechanical properties than the hydrogel containing only rigid chains. Calculations showed that the crosslinking ratio in the hydrogel formed by flexible chains was about twice that of the hydrogel formed by rigid chains under the same conditions. We attributed this to the ease of conformational adjustment of flexible chains. Incorporation of 25% rigid chains further improved the performance of DNA hydrogel by shrinking the pore size and tuning its distribution. PMID:27121600

  9. A biomimetic porous hydrogel of gelatin and glycosaminoglycans cross-linked with transglutaminase and its application in the culture of hepatocytes

    International Nuclear Information System (INIS)

    The development of blended gelatin and glycosaminoglycan (GAG) scaffolds can potentially be used in many soft tissue engineering applications since these scaffolds mimic the structure and biological function of native extracellular matrix (ECM). In this study, we were able to obtain a gelatin–GAG scaffold by using a concentrated emulsion templating technique known as high internal phase emulsion (HIPE), in which a prevailing in volume organic phase is dispersed in the form of discrete droplets inside an aqueous solution of three biopolymers represented by gelatin, hyaluronic acid (HA) and chondroitin sulfate (CS) in the presence of a suitable surfactant. In order to preserve the bioactive potential of the biopolymers employed, the cross-linking procedure involved the use of transglutaminase (MTGase) that catalyzes the formation of covalent N-ε-(γ-glutamyl) lysine amide bonds. Since neither HA nor CS possess the necessary primary amino groups toward which MTGase is active, they were functionalized with the dipeptide glycine-lysine (GK). In this way the introduction of foreign cross-linking bridging units with an unpredictable biocompatibility was avoided. These enzymatic cross-linked gelatin–GAG scaffolds were tested in the culture of primary rat and C3A hepatocytes. Results underlined the good performance of this novel support in maintaining and promoting hepatocyte functions in vitro. (paper)

  10. Macrojunctions ordering in polyelectrolyte hydrogels

    Science.gov (United States)

    Török, Gy; Lebedev, V. T.; Cser, L.; Buyanov, A. L.; Revelskaya, L. G.

    2000-03-01

    We studied the structure of polyelectrolyte hydrogels of sodium polyacrylate cross-linked by macromolecular allyldextran (supergels). Using high-resolution SANS we have found the specific ordering of macrojunctions (structure's period ∼130 nm) that may be reliable for the network's anomaly swelling.

  11. Structural Parameters and Swelling Behavior of pH Sensitive Poly(acrylamide-co-acrylic acid) Hydrogels

    OpenAIRE

    Thakur, A; Wanchoo, R. K.; Singh, P

    2011-01-01

    In the present work, hydrogels based on acrylamide (AAm) and acrylic acid (AAc), crosslinked with N,N’-methylenebisacrylamide (MBAAm) were prepared by free radical polymerization in solution. The effect of initial AAm/AAc mole ratio and nominal crosslinking ratio (moles of crosslinking agent/moles of polymer repeat unit) on the dynamic and equilibrium swelling behaviour of hydrogels was investigated. Hydrogels were characterized by the polymer volume fraction in the swollen state (ν2,s ), the...

  12. 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)

    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

  13. 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.

  14. Modulation of Dental Pulp Stem Cell Odontogenesis in a Tunable PEG-Fibrinogen Hydrogel System

    Science.gov (United States)

    Lu, Qiqi; Pandya, Mirali; Rufaihah, Abdul Jalil; Rosa, Vinicius; Tong, Huei Jinn; Seliktar, Dror; Toh, Wei Seong

    2015-01-01

    Injectable hydrogels have the great potential for clinical translation of dental pulp regeneration. A recently developed PEG-fibrinogen (PF) hydrogel, which comprises a bioactive fibrinogen backbone conjugated to polyethylene glycol (PEG) side chains, can be cross-linked after injection by photopolymerization. The objective of this study was to investigate the use of this hydrogel, which allows tuning of its mechanical properties, as a scaffold for dental pulp tissue engineering. The cross-linking degree of PF hydrogels could be controlled by varying the amounts of PEG-diacrylate (PEG-DA) cross-linker. PF hydrogels are generally cytocompatible with the encapsulated dental pulp stem cells (DPSCs), yielding >85% cell viability in all hydrogels. It was found that the cell morphology of encapsulated DPSCs, odontogenic gene expression, and mineralization were strongly modulated by the hydrogel cross-linking degree and matrix stiffness. Notably, DPSCs cultured within the highest cross-linked hydrogel remained mostly rounded in aggregates and demonstrated the greatest enhancement in odontogenic gene expression. Consistently, the highest degree of mineralization was observed in the highest cross-linked hydrogel. Collectively, our results indicate that PF hydrogels can be used as a scaffold for DPSCs and offers the possibility of influencing DPSCs in ways that may be beneficial for applications in regenerative endodontics. PMID:26124841

  15. Modulation of Dental Pulp Stem Cell Odontogenesis in a Tunable PEG-Fibrinogen Hydrogel System.

    Science.gov (United States)

    Lu, Qiqi; Pandya, Mirali; Rufaihah, Abdul Jalil; Rosa, Vinicius; Tong, Huei Jinn; Seliktar, Dror; Toh, Wei Seong

    2015-01-01

    Injectable hydrogels have the great potential for clinical translation of dental pulp regeneration. A recently developed PEG-fibrinogen (PF) hydrogel, which comprises a bioactive fibrinogen backbone conjugated to polyethylene glycol (PEG) side chains, can be cross-linked after injection by photopolymerization. The objective of this study was to investigate the use of this hydrogel, which allows tuning of its mechanical properties, as a scaffold for dental pulp tissue engineering. The cross-linking degree of PF hydrogels could be controlled by varying the amounts of PEG-diacrylate (PEG-DA) cross-linker. PF hydrogels are generally cytocompatible with the encapsulated dental pulp stem cells (DPSCs), yielding >85% cell viability in all hydrogels. It was found that the cell morphology of encapsulated DPSCs, odontogenic gene expression, and mineralization were strongly modulated by the hydrogel cross-linking degree and matrix stiffness. Notably, DPSCs cultured within the highest cross-linked hydrogel remained mostly rounded in aggregates and demonstrated the greatest enhancement in odontogenic gene expression. Consistently, the highest degree of mineralization was observed in the highest cross-linked hydrogel. Collectively, our results indicate that PF hydrogels can be used as a scaffold for DPSCs and offers the possibility of influencing DPSCs in ways that may be beneficial for applications in regenerative endodontics. PMID:26124841

  16. Modulation of Dental Pulp Stem Cell Odontogenesis in a Tunable PEG-Fibrinogen Hydrogel System

    Directory of Open Access Journals (Sweden)

    Qiqi Lu

    2015-01-01

    Full Text Available Injectable hydrogels have the great potential for clinical translation of dental pulp regeneration. A recently developed PEG-fibrinogen (PF hydrogel, which comprises a bioactive fibrinogen backbone conjugated to polyethylene glycol (PEG side chains, can be cross-linked after injection by photopolymerization. The objective of this study was to investigate the use of this hydrogel, which allows tuning of its mechanical properties, as a scaffold for dental pulp tissue engineering. The cross-linking degree of PF hydrogels could be controlled by varying the amounts of PEG-diacrylate (PEG-DA cross-linker. PF hydrogels are generally cytocompatible with the encapsulated dental pulp stem cells (DPSCs, yielding >85% cell viability in all hydrogels. It was found that the cell morphology of encapsulated DPSCs, odontogenic gene expression, and mineralization were strongly modulated by the hydrogel cross-linking degree and matrix stiffness. Notably, DPSCs cultured within the highest cross-linked hydrogel remained mostly rounded in aggregates and demonstrated the greatest enhancement in odontogenic gene expression. Consistently, the highest degree of mineralization was observed in the highest cross-linked hydrogel. Collectively, our results indicate that PF hydrogels can be used as a scaffold for DPSCs and offers the possibility of influencing DPSCs in ways that may be beneficial for applications in regenerative endodontics.

  17. Hydrogels in a historical perspective: From simple networks to smart materials

    NARCIS (Netherlands)

    Buwalda, S.J.; Boere, K.W.M.; Dijkstra, Pieter J.; Feijen, J.; Vermonden, T.; Hennink, W.E.

    2014-01-01

    Over the past decades, significant progress has been made in the field of hydrogels as functional biomaterials. Biomedical application of hydrogels was initially hindered by the toxicity of crosslinking agents and limitations of hydrogel formation under physiological conditions. Emerging knowledge i

  18. Gelam (Melaleuca spp.) Honey-Based Hydrogel as Burn Wound Dressing

    OpenAIRE

    Rozaini Mohd Zohdi; Zuki Abu Bakar Zakaria; Norimah Yusof; Noordin Mohamed Mustapha; Muhammad Nazrul Hakim Abdullah

    2012-01-01

    A novel cross-linked honey hydrogel dressing was developed by incorporating Malaysian honey into hydrogel dressing formulation, cross-linked and sterilized using electron beam irradiation (25 kGy). In this study, the physical properties of the prepared honey hydrogel and its wound healing efficacy on deep partial thickness burn wounds in rats were assessed. Skin samples were taken at 7, 14, 21, and 28 days after burn for histopathological and molecular evaluations. Application of honey hydrog...

  19. Arct'Alg release from hydrogel membranes

    International Nuclear Information System (INIS)

    The hydrogel properties make them attractive for a variety of biomedical and pharmaceutical applications, primarily in drug delivery system. Synthetic hydrogels have been studied to develop new devices for drugs or cosmetic active agents release. Arct'AlgR is an extract derived from red algae biomass which has antioxidant, anti-inflammatory and tissue regeneration stimulant properties. This extract was incorporated to poly(N-vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) hydrogel membranes obtained by gamma rays crosslinking technique. The ionizing radiation presents the advantage to occur polymerization and sterilization simultaneously in the same process. The aim of this work was the in vitro release kinetic study of Arct'AlgR from hydrogel membranes during 24 hours to verify the possibility of use in cosmetic and dermatological treatments. Results showed that about 50% and 30% of incorporated Arct'AlgR was released from PVP and PVA hydrogel membrane devices respectively. (author)

  20. Enzyme-catalysed assembly of DNA hydrogel

    Science.gov (United States)

    Um, Soong Ho; Lee, Jong Bum; Park, Nokyoung; Kwon, Sang Yeon; Umbach, Christopher C.; Luo, Dan

    2006-10-01

    DNA is a remarkable polymer that can be manipulated by a large number of molecular tools including enzymes. A variety of geometric objects, periodic arrays and nanoscale devices have been constructed. Previously we synthesized dendrimer-like DNA and DNA nanobarcodes from branched DNA via ligases. Here we report the construction of a hydrogel entirely from branched DNA that are three-dimensional and can be crosslinked in nature. These DNA hydrogels were biocompatible, biodegradable, inexpensive to fabricate and easily moulded into desired shapes and sizes. The distinct difference of the DNA hydrogel to other bio-inspired hydrogels (including peptide-based, alginate-based and DNA (linear)-polyacrylamide hydrogels) is that the crosslinking is realized via efficient, ligase-mediated reactions. The advantage is that the gelling processes are achieved under physiological conditions and the encapsulations are accomplished in situ-drugs including proteins and even live mammalian cells can be encapsulated in the liquid phase eliminating the drug-loading step and also avoiding denaturing conditions. Fine tuning of these hydrogels is easily accomplished by adjusting the initial concentrations and types of branched DNA monomers, thus allowing the hydrogels to be tailored for specific applications such as controlled drug delivery, tissue engineering, 3D cell culture, cell transplant therapy and other biomedical applications.

  1. Self-Healing Hydrogels Based on Carboxymethyl Chitosan and Acryloyl-6-aminocaproic Acid

    OpenAIRE

    Jiufang Duan

    2015-01-01

    Once cracks have formed within hydrogel materials, the integrity of the structure is signifcantly compromised, regardless of the application. Here, we demonstrate cross-linked CMCS hydrogels can be engineered to exhibit self-healing under mild conditions. CMCS hydrogels based on CMCS and acryloyl-6-aminocaproic acid (A6ACA) were synthesized by free radical aqueous copolymerization using ammonium persulfate as initiator. A series of hydrogels was synthesized varying the percentage of A6ACA. T...

  2. Multicomponent vinylpyrrolidone hydrogels and use thereof in tissue engineering and/or regenerative medicine

    OpenAIRE

    Gallardo Ruiz, Alberto; Aranaz, Inmaculada; Nash, María E.; Gómez Tardajos, Myriam; Elvira, Carlos; Reinecke, Helmut; Martínez-Campos, Enrique; Ramos, Viviana; López-Lacomba, José Luis

    2014-01-01

    [EN] The invention relates to a hydrogel having a cross-linked multicomponent polymer network structure, characterised in that said hydrogel includes: a) blocks derived from vinylpyrrolidone (V) and blocks derived from an anionic or anionisable alkene monomer (A), wherein the reactivity ratios in binary radical copolymerisation of (V) and (A) have maximum and minimum values of 0.5, respectively; and b) blocks derived from at least one cross-linking agent; as long as the one or more cross-link...

  3. Nanostructuring PEG-fibrinogen hydrogels to control cellular morphogenesis.

    Science.gov (United States)

    Frisman, Ilya; Seliktar, Dror; Bianco-Peled, Havazelet

    2011-11-01

    The nanostructuring of hydrogel scaffolds used in tissue engineering aims to provide an ability to control cellular morphogenesis through defined cell-matrix interactions. Toward this objective, we developed a method that alters the molecular network structure of biosynthetic hydrogel scaffolds made from crosslinked poly(ethylene glycol)-fibrinogen conjugates (PEG-fibrinogen, PF). The modifications were based on Pluronic(®) F127 micelles that were formed in the hydrogel precursor solution and that altered the hydrogel network assembly during photopolymerization crosslinking. Two variations of the cell-encapsulating hydrogels (high and low crosslinking density) were prepared with three concentrations of Pluronic(®) F127 (3%, 7%, 10% w/v). Quantitative morphometrics were used to characterize fibroblast shape parameters (both transient and stable) in all hydrogels, and rheological characterizations were used to measure the elastic (storage) component of the complex shear modulus of these hydrogels. The morphometric data was then correlated to both the nanostructure and modulus of the hydrogels for day 1 and day 4 in culture. These correlations revealed that structural features imparted by the Pluronic(®) F127 micelles were able to reverse the normally strong correlations found between indicators of cell spreading and the hydrogel's mechanical properties. Therefore, the data supports the conclusion that nanostructural features in the encapsulating hydrogel culture environment can facilitate better cell spreading in a dense hydrogel milieu, simply by introducing imperfections into the network structure. This research also provides further prospective regarding biocompatible approaches toward making structural modifications to hydrogel scaffolds for the purpose of 3-D cell culture and tissue engineering. PMID:21784517

  4. Radiation preparation and characteristics of sodium carboxymethyl cellulose hydrogels

    International Nuclear Information System (INIS)

    Sodium carboxymethyl cellulose (CMC) is a kind of degraded polymer under irradiation. However, in this work, it can be found that CMC crosslink partially to form hydrogel by radiation technique at more than 20% CMC aqueous solution. The gel fraction increases with the dose. The crosslinking reaction of CMC is promoted in the presence of N2 or N2O due to the increasing of free radicals on CMC backbone, but gel fraction of CMC hydrogel isn't high (less than 40%). Some important values related to this kind of new CMC hydrogel synthesized at different conditions, such as radiation yield of crosslinking G(x), gelation dose Rg, number average molecular weight of network Mc is calculated according to Charlesky-Pinner equation. The results indicated that although crosslinked CMC hydrogel can be prepared by radiation method, the rate of radiation degradation of CMC is faster than that of radiation crosslinking due to the character of CMC itself. Swelling dynamics of CMC hydrogel and its swelling behavior at different conditions, such as acidic, basic, inorganic salt as well as temperature is investigated, too. Strong acidity, strong basicity, small amount of inorganic salts and lower temperature can reduce swelling ratio. Because of no toxicity and good biocompatibility of natural polymer, CMC based hydrogel will have wide application in biomedical materials. (author)

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

    International Nuclear Information System (INIS)

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

  6. Hybrid Supramolecular and Colloidal Hydrogels that Bridge Multiple Length Scales**

    Science.gov (United States)

    Janeček, Emma-Rose; McKee, Jason R; Tan, Cindy S Y; Nykänen, Antti; Kettunen, Marjo; Laine, Janne; Ikkala, Olli; Scherman, Oren A

    2015-01-01

    Hybrid nanocomposites were constructed based on colloidal nanofibrillar hydrogels with interpenetrating supramolecular hydrogels, displaying enhanced rheological yield strain and a synergistic improvement in storage modulus. The supramolecular hydrogel consists of naphthyl-functionalized hydroxyethyl cellulose and a cationic polystyrene derivative decorated with methylviologen moieties, physically cross-linked with cucurbit[8]uril macrocyclic hosts. Fast exchange kinetics within the supramolecular system are enabled by reversible cross-linking through the binding of the naphthyl and viologen guests. The colloidal hydrogel consists of nanofibrillated cellulose that combines a mechanically strong nanofiber skeleton with a lateral fibrillar diameter of a few nanometers. The two networks interact through hydroxyethyl cellulose adsorption to the nanofibrillated cellulose surfaces. This work shows methods to bridge the length scales of molecular and colloidal hybrid hydrogels, resulting in synergy between reinforcement and dynamics. PMID:25772264

  7. Hydrogel based occlusion systems

    OpenAIRE

    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 target occlusion location. The hydrogel is configured to permanently occlude the target occlusion location in the swollen state. The hydrogel may be an electro-activated hydrogel (EAH) which could be ...

  8. Gamma radiation synthesis of rapid swelling superporous polyacrylamide hydrogels

    International Nuclear Information System (INIS)

    In this report a simple route for gamma radiation induced synthesis of superporous hydrogel (SPH) is described. Conventional SPH synthesis requires foaming and cross-linking reactions to take place simultaneously. However, in radiation synthesis it is difficult to introduce foaming during the cross-linking reactions. In order to overcome this limitation, the foaming and radiation cross-linking reactions were decoupled and carried out in two stages. The polyacrylamide SPH synthesized by this approach has very fast swelling kinetics compared to the non-porous hydrogel.

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

    Science.gov (United States)

    Farhoudian, Sana; Yadollahi, Mehdi; Namazi, Hassan

    2016-01-01

    CuO nanoparticles were synthesized in situ during the formation of physically cross-linked chitosan hydrogel beads using sodium tripolyphosphate as the cross-linker. The aim of the study was to investigate whether these nanocomposite beads have the potential to be used in drug delivery applications. The formation of CuO nanoparticles (CuONPs) in the hydrogels was confirmed by X-ray diffraction and scanning electron microscopy studies. SEM micrographs revealed the formation of CuONPs with size range of 10-25 nm within the hydrogel matrix. Furthermore, the antibacterial and swelling properties of the beads were studied. The prepared nanocomposite hydrogels showed a pH sensitive swelling behavior. The CuO nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with neat hydrogel. The nanocomposite hydrogels demonstrated good antibacterial effects against Escherichia coli and Staphylococcus aureus bacteria. PMID:26454107

  10. Biodegradable HEMA-based hydrogels with enhanced mechanical properties.

    Science.gov (United States)

    Moghadam, Mohamadreza Nassajian; Pioletti, Dominique P

    2016-08-01

    Hydrogels are widely used in the biomedical field. Their main purposes are either to deliver biological active agents or to temporarily fill a defect until they degrade and are followed by new host tissue formation. However, for this latter application, biodegradable hydrogels are usually not capable to sustain any significant load. The development of biodegradable hydrogels presenting load-bearing capabilities would open new possibilities to utilize this class of material in the biomedical field. In this work, an original formulation of biodegradable photo-crosslinked hydrogels based on hydroxyethyl methacrylate (HEMA) is presented. The hydrogels consist of short-length poly(2-hydroxyethyl methacrylate) (PHEMA) chains in a star shape structure, obtained by introducing a tetra-functional chain transfer agent in the backbone of the hydrogels. They are cross-linked with a biodegradable N,O-dimethacryloyl hydroxylamine (DMHA) molecule sensitive to hydrolytic cleavage. We characterized the degradation properties of these hydrogels submitted to mechanical loadings. We showed that the developed hydrogels undergo long-term degradation and specially meet the two essential requirements of a biodegradable hydrogel suitable for load bearing applications: enhanced mechanical properties and low molecular weight degradation products. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1161-1169, 2016. PMID:26061346

  11. Injectable hyaluronic acid-dextran hydrogels and effects of implantation in ferret vocal fold.

    Science.gov (United States)

    Luo, Ying; Kobler, James B; Heaton, James T; Jia, Xinqiao; Zeitels, Steven M; Langer, Robert

    2010-05-01

    Injectable hydrogels may potentially be used for augmentation/regeneration of the lamina propria of vocal fold tissue. In this study, hyaluronic acid (HA) and dextran were chemically modified and subsequently crosslinked via formation of hydrazone bonds in phosphate buffer. Swelling ratios, degradation, and compressive moduli of the resulting hydrogels were investigated. It was found that the properties of HA-dextran hydrogels were variable and the trend of variation could be correlated with the hydrogel composition. The biocompatibility of three injectable HA-dextran hydrogels with different crosslinking density was assessed in the vocal fold region using a ferret model. It was found that HA-dextran hydrogels implanted for three weeks stimulated mild foreign-body reactions. Distinct tissue-material interactions were also observed for hydrogels made from different formulations: the hydrogel with the lowest crosslinking density was completely degraded in vivo; while material residues were visible for other types of hydrogel injections, with or without cell penetration into the implantation depending on the hydrogel composition. The in vivo results suggest that the HA-dextran hydrogel matrices can be further developed for applications of vocal fold tissue restoration. PMID:20151459

  12. ADDITIVE-INDUCED ENHANCEMENT OF OPTICAL CLARITY OF POLYACRYLAMIDE HYDROGEL

    Institute of Scientific and Technical Information of China (English)

    Jeffery Franklin; Zhi Yuan Wang

    2003-01-01

    The aqueous polymerization of acrylamide and crosslinking with N,N-methylenebisacrylamide afforded hydrogels displaying high levels of light scattering (poor optical clarity). Enhancement of the optical clarity within a polyacrylamide (PAm) hydrogel was accomplished through the implementation of"refractive index matching", Water-soluble additives were utilised to better match the refractive index inhomogeneities throughout a given hydrogel. This resulted in lower light scattering within the system and hence improved clarity. Amino acids, sugars, polymers, and other water-soluble additives such as glycerol were investigated by this methodology. Most additives investigated displayed potential for effectively reducing the light scattering within a PAm hydrogel as a function of increased additive concentration. On increasing the refractive index of the water medium, the overall refractive index of a PAm hydrogel was also observed to increase. This provided a quantitative means of determining the effectiveness of a given additive for improving the optical clarity within a hydrogel.

  13. Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications

    Directory of Open Access Journals (Sweden)

    Assunta Borzacchiello

    2015-01-01

    Full Text Available Hyaluronic acid (HA hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injectability, and network structural parameters. They exhibit a rheological behaviour typical of strong gels and show improved viscoelastic properties by increasing HA concentration and decreasing HA/DVS weight ratio. Furthermore, it was demonstrated that processes such as sterilization and extrusion through clinical needles do not imply significant alteration of viscoelastic properties. Both SANS and rheological tests indicated that the cross-links appear to compact the network, resulting in a reduction of the mesh size by increasing the cross-linker amount. In vitro degradation tests of the HA hydrogels demonstrated that these new hydrogels show a good stability against enzymatic degradation, which increases by increasing HA concentration and decreasing HA/DVS weight ratio. Finally, the hydrogels show a good biocompatibility confirmed by in vitro tests.

  14. Macroporous hydrogels based on 2-hydroxyethyl methacrylate. Part 3. Hydrogels as carriers for immobilization of proteins

    Czech Academy of Sciences Publication Activity Database

    Michálek, Jiří; Přádný, Martin; Artyukhov, A.; Šlouf, Miroslav; Smetana Jr., K.

    2005-01-01

    Roč. 16, č. 8 (2005), s. 783-786. ISSN 0957-4530 R&D Projects: GA ČR GA203/01/0737; GA AV ČR IBS4050005; GA MŠk LN00A065 Keywords : macroporous hydrogels * hydroxyethyl methacrylate * crosslinked copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.248, year: 2005

  15. Rapid Synthesis of Superabsorbent Smart-Swelling Bacterial Cellulose/Acrylamide-Based Hydrogels for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Manisha Pandey

    2013-01-01

    Full Text Available This study evaluated the effect of solubilized and dispersed bacterial cellulose (BC on the physicochemical characteristics and drug release profile of hydrogels synthesized using biopolymers. Superabsorbent hydrogels were synthesized by graft polymerization of acrylamide on BC solubilized in an NaOH/urea solvent system and on dispersed BC by using N,N′-methylenebisacrylamide as a crosslinker under microwave irradiation. Fourier transform infrared spectroscopy analysis of the resulting hydrogels confirmed the grafting, and an X-ray diffraction pattern showed a decrease in the crystallinity of BC after the grafting process. The hydrogels exhibited pH and ionic responsive swelling behavior, with hydrogels prepared using solubilized BC (SH having higher swelling ratios. Furthermore, compared to the hydrogels synthesized using dispersed BC, the hydrogels synthesized using solubilized BC showed higher porosity, drug loading efficiency, and release. These results suggest the superiority of the hydrogels prepared using solubilized BC and that they should be explored further for oral drug delivery.

  16. 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 tar

  17. Designing Visible Light-Cured Thiol-Acrylate Hydrogels for Studying the HIPPO Pathway Activation in Hepatocellular Carcinoma Cells.

    Science.gov (United States)

    Lin, Tsai-Yu; Bragg, John C; Lin, Chien-Chi

    2016-04-01

    Various polymerization mechanisms have been developed to prepare peptide-immobilized poly(ethylene glycol) (PEG) hydrogels, a class of biomaterials suitable for studying cell biology in vitro. Here, a visible light mediated thiol-acrylate photopolymerization scheme is reported to synthesize dually degradable PEG-peptide hydrogels with controllable crosslinking and degradability. The influence of immobilized monothiol pendant peptide is systematically evaluated on the crosslinking of these hydrogels. Further, methods are proposed to modulate hydrogel crosslinking, including adjusting concentration of comonomer or altering the design of multifunctional peptide crosslinker. Due to the formation of thioether ester bonds, these hydrogels are hydrolytically degradable. If the dithiol peptide linkers used are susceptible to protease cleavage, these thiol-acrylate hydrogels can be designed to undergo partial proteolysis. The differences between linear and multiarm PEG-acrylate (i.e., PEGDA vs PEG4A) are also evaluated. Finally, the use of the mixed-mode thiol-acrylate PEG4A-peptide hydrogels is explored for in situ encapsulation of hepatocellular carcinoma cells (Huh7). The effects of matrix stiffness and integrin binding motif (e.g., RGDS) on Huh7 cell growth and HIPPO pathway activation are studied using PEG4A-peptide hydrogels. This visible light poly-merized thiol-acrylate hydrogel system represents an alternative to existing light-cured hydrogel platforms and shall be useful in many biomedical applications. PMID:26709469

  18. Color stabilized hydrogel dressing and process

    International Nuclear Information System (INIS)

    A polyvinylpyrrolidone (PVP) Silver Sulfadiazine (SSD) hydrogel dressing in which the gel is formed by the use of electron beam (E-Beam) radiation to cross-link the polyvinylpyrrolidone (PVP); in which the color of the hydrogel dressing has been stabilized by the addition thereto of magnesium trisilicate and, optionally but preferably, also hydrogen peroxide and/or polyacrylic acid is disclosed; and also the process of stabilizing the color by adding magnesium trisilicate, to a water dispersion of PVP and SSD before it is exposed to E-Beam radiation is disclosed

  19. Porous Hydrogels

    Czech Academy of Sciences Publication Activity Database

    Přádný, Martin; Michálek, Jiří; Širc, Jakub

    New York: Nova Science Publishers, 2009 - (Acosta, J.; Camacho, A.), s. 57-74 ISBN 978-1-60741-401-8 R&D Projects: GA AV ČR 1QS400500558; GA MŠk 1M0538 Institutional research plan: CEZ:AV0Z40500505 Keywords : hydrogels * porous * tissue engineering Subject RIV: CD - Macromolecular Chemistry

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

    Science.gov (United States)

    Shih, Han; Lin, Chien-Chi

    2015-07-13

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

  1. Hydrogel membrane CEACEL preparation at CEADEN for biomedical application. Characterization and quality control

    International Nuclear Information System (INIS)

    The hydrogel membrane production was done at CEADEN using gamma irradiation facility. It's based on the synthesis, crosslinking and sterilization of the mixture of polyvinylpyrrolidone, polyethylene glycol, agar and water. The quality of the production process of hydrogels is monitored throughout the process to ensure the reliability and traceability of the final product according to the good manufacture practices. The hydrogel membranes production for biomedical applications have been gotten the medical register by CECMED. (Author)

  2. Modulation of Dental Pulp Stem Cell Odontogenesis in a Tunable PEG-Fibrinogen Hydrogel System

    OpenAIRE

    Qiqi Lu; Mirali Pandya; Abdul Jalil Rufaihah; Vinicius Rosa; Huei Jinn Tong; Dror Seliktar; Wei Seong Toh

    2015-01-01

    Injectable hydrogels have the great potential for clinical translation of dental pulp regeneration. A recently developed PEG-fibrinogen (PF) hydrogel, which comprises a bioactive fibrinogen backbone conjugated to polyethylene glycol (PEG) side chains, can be cross-linked after injection by photopolymerization. The objective of this study was to investigate the use of this hydrogel, which allows tuning of its mechanical properties, as a scaffold for dental pulp tissue engineering. The cross-li...

  3. Biomedical applications of hydrogels: a review of patents and commercial products

    OpenAIRE

    Caló, Enrica; Khutoryanskiy, Vitaliy V.

    2015-01-01

    Hydrogels have become very popular due to their unique properties such as high water content, softness, flexibility and biocompatibility. Natural and synthetic hydrophilic polymers can be physically or chemically cross-linked in order to produce hydrogels. Their resemblance to living tissue opens up many opportunities for applications in biomedical areas. Currently, hydrogels are used for manufacturing contact lenses, hygiene products, tissue engineering scaffolds, drug delivery systems and w...

  4. In Situ Synthesis of Magnetic Field-Responsive Hemicellulose Hydrogels for Drug Delivery

    OpenAIRE

    Zhao, Weifeng; Odelius, Karin; Edlund, Ulrica; Zhao, Changsheng; Albertsson, Ann-Christine

    2015-01-01

    A one-pot synthetic methodology for fabricating stimuli-responsive hemicellulose-based hydrogels was developed that consists of the in situ formation of magnetic iron oxide (Fe3O4) nanoparticles during the covalent cross-linking of O-acetyl-galactoglucomannan (AcGGM). The Fe3O4 nanoparticle content controlled the thermal stability, macrostructure, swelling behavior, and magnetization of the hybrid hydrogels. In addition, the magnetic field-responsive hemicellulose hydrogels (MFRHHs) exhibited...

  5. 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.

  6. Delivery of Rosiglitazone from an Injectable Triple Interpenetrating Network Hydrogel Composed of Naturally Derived Materials

    OpenAIRE

    Zhang, Hanwei; Qadeer, Aisha; Mynarcik, Dennis; Chen, Weiliam

    2010-01-01

    An in situ gelable and biodegradable triple-interpenetrating network (3XN) hydrogel, completely devoid of potentially cytotoxic extraneous small molecule crosslinkers, is formulated from partially oxidized dextran (Odex), teleostean and N-carboxyethyl chitosan (CEC). Both the rheological profile and mechanical strength of the 3XN hydrogel approximate the combined characteristics of the three individual hydrogels composed of the binary partial formulations (i.e., Odex/CEC, Odex/teleostean, and...

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

    OpenAIRE

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

    2010-01-01

    This report details the first experimental results from novel hydrogel sensor array (2 × 2) which incorporates analyte diffusion pores into a piezoresistive diaphragm for the detection of hydrogel swelling pressures and hence chemical concentrations. The sensor assembly was comprised of three components, the active four sensors, HPMA/DMA/TEGDMA (hydroxypropyl methacrylate (HPMA), N,N-dimethylaminoethyl methacrylate (DMA) and crosslinker tetra-ethyleneglycol dimethacrylate (TEGDMA)) hydrogel, ...

  8. Multi-functions of hydrogel with bilayer-based lamellar structure

    OpenAIRE

    Haque, Md. Anamul; Gong, Jian Ping

    2013-01-01

    A novel hybrid hydrogel has been developed by combining bilayer-based lamellar structure of a self-assembled polymer surfactant and polymer network of conventional hydrogel system. A wide range of lamellar structure from micro-domain up to macro-domain (cm-scale) has been successfully generated in the hydrogel. Flat, infinitely large, and perfectly aligned lamellar macro-domain was formed by applying mechanical shear to the gel forming precursor solution containing monomer, cross-linker, and ...

  9. Preparation and Characterization of Organic-Inorganic Hybrid Hydrogel Electrolyte Using Alkaline Solution

    OpenAIRE

    Masanobu Chiku; Shoji Tomita; Eiji Higuchi; Hiroshi Inoue

    2011-01-01

    Organic-inorganic hybrid hydrogel electrolytes were prepared by mixing hydrotalcite, cross-linked potassium poly(acrylate) and 6 M KOH solution. The organic-inorganic hybrid hydrogel electrolytes had high ionic conductivity (0.456–0.540 S cm−1) at 30 °C. Moreover, the mechanical strength of the hydrogel electrolytes was high enough to form a 2–3 mm thick freestanding membrane because of the reinforcement with hydrotalcite.

  10. Self-Healing Hydrogels Based on Carboxymethyl Chitosan and Acryloyl-6-aminocaproic Acid

    Directory of Open Access Journals (Sweden)

    Jiufang Duan

    2015-01-01

    Full Text Available Once cracks have formed within hydrogel materials, the integrity of the structure is signifcantly compromised, regardless of the application. Here, we demonstrate cross-linked CMCS hydrogels can be engineered to exhibit self-healing under mild conditions. CMCS hydrogels based on CMCS and acryloyl-6-aminocaproic acid (A6ACA were synthesized by free radical aqueous copolymerization using ammonium persulfate as initiator. A series of hydrogels was synthesized varying the percentage of A6ACA. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR techniques and their morphologies were investigated by scanning electron microscope (SEM images. When the proportion of A6ACA was increased, the compressive strength, stress, and strain of hydrogels were increased. The cross-linked hydrogel based on CMCS that can autonomously heal between cut surfaces after 1 h was formed under mild conditions. The increase of A6ACA content in the hydrogels will lead to increased mechanical properties and mechanical healing efficiencies for highly cross-linked polymeric networks. Hydrogen bond is the main reason for self-healing ability, and the covalent cross-linkss and noncovalent cross-links both bear loads in the hyrogel. Polymers with the ability to self-repair after sustaining damage could extend the lifetime of materials used in many applications.

  11. 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.

  12. Mussel-mimetic protein-based adhesive hydrogel.

    Science.gov (United States)

    Kim, Bum Jin; Oh, Dongyeop X; Kim, Sangsik; Seo, Jeong Hyun; Hwang, Dong Soo; Masic, Admir; Han, Dong Keun; Cha, Hyung Joon

    2014-05-12

    Hydrogel systems based on cross-linked polymeric materials which could provide both adhesion and cohesion in wet environment have been considered as a promising formulation of tissue adhesives. Inspired by marine mussel adhesion, many researchers have tried to exploit the 3,4-dihydroxyphenylalanine (DOPA) molecule as a cross-linking mediator of synthetic polymer-based hydrogels which is known to be able to achieve cohesive hardening as well as adhesive bonding with diverse surfaces. Beside DOPA residue, composition of other amino acid residues and structure of mussel adhesive proteins (MAPs) have also been considered important elements for mussel adhesion. Herein, we represent a novel protein-based hydrogel system using DOPA-containing recombinant MAP. Gelation can be achieved using both oxdiation-induced DOPA quinone-mediated covalent and Fe(3+)-mediated coordinative noncovalent cross-linking. Fe(3+)-mediated hydrogels show deformable and self-healing viscoelastic behavior in rheological analysis, which is also well-reflected in bulk adhesion strength measurement. Quinone-mediated hydrogel has higher cohesive strength and can provide sufficient gelation time for easier handling. Collectively, our newly developed MAP hydrogel can potentially be used as tissue adhesive and sealant for future applications. PMID:24650082

  13. Injectable in situ forming xylitol-PEG-based hydrogels for cell encapsulation and delivery.

    Science.gov (United States)

    Selvam, Shivaram; Pithapuram, Madhav V; Victor, Sunita P; Muthu, Jayabalan

    2015-02-01

    Injectable in situ crosslinking hydrogels offer unique advantages over conventional prefabricated hydrogel methodologies. Herein, we synthesize poly(xylitol-co-maleate-co-PEG) (pXMP) macromers and evaluate their performance as injectable cell carriers for tissue engineering applications. The designed pXMP elastomers were non-toxic and water-soluble with viscosity values permissible for subcutaneous injectable systems. pXMP-based hydrogels prepared via free radical polymerization with acrylic acid as crosslinker possessed high crosslink density and exhibited a broad range of compressive moduli that could match the natural mechanical environment of various native tissues. The hydrogels displayed controlled degradability and exhibited gradual increase in matrix porosity upon degradation. The hydrophobic hydrogel surfaces preferentially adsorbed albumin and promoted cell adhesion and growth in vitro. Actin staining on cells cultured on thin hydrogel films revealed subconfluent cell monolayers composed of strong, adherent cells. Furthermore, fabricated 3D pXMP cell-hydrogel constructs promoted cell survival and proliferation in vitro. Cumulatively, our results demonstrate that injectable xylitol-PEG-based hydrogels possess excellent physical characteristics and exhibit exceptional cytocompatibility in vitro. Consequently, they show great promise as injectable hydrogel systems for in situ tissue repair and regeneration. PMID:25543981

  14. Injectable Biopolymer-hydroxyapatite Hydrogels: Obtaining and their Characterization

    Directory of Open Access Journals (Sweden)

    L.B. Sukhodub

    2016-03-01

    Full Text Available Hydrogels based on hydroxyapatite (HA and Chitosan (CS with addition of sodium alginate (Alg were synthesized by in situ precipitation method. Structure, morphology, chemical and phase composition of the HA/CS and HA/CS/Alg hydrogels were characterized by TEM, FTIR and XRD. Hydrogels consist of low crystallinity calcium deficient hydroxyapatite (JCPDS 9 432, the needle-like crystallites have an average size 25 nm. The introduction of Alginate powder into HA/CS hydrogel solution demonstrate the viscosity enhancing of the HA/CS hydrogel due to polyelectrolyte reaction between Alginate and Chitosan macromolecules. Two natural polymers and partially released from hydroxyapatite Ca2+ ions formed a matrix by crosslinking the polymer macromolecules through hydroxyl, amino and carbonyl groups. These processes promote the formation of a more stable structure of HA/CS/Alg hydrogel as compared to HA/CS. The structural integrity and degradation tests have demonstrated that HA/CS/Alg1.0 saved its initial shape in 7 days of shaking in SBF solution, meanwhile for HA/CS, a structural decay was observed. The HA/CS hydrogel had completely lost its volume support after 1 day shaking in SBF. Thus, the ability of HA/CS hydrogel to maintain its shape with implantation into bone tissue defect may be enhanced with alginate addition, but alginate content more than 1 w/w % reduces the hydrogel plasticity, increases the swelling and accelerates the shape decay.

  15. Radiation synthesis and characterization of gelatine category hydrogel

    International Nuclear Information System (INIS)

    The hydrogels based on gelatine cross-linked with sodium carboxymethyl cellulose (CMC-Na) and polyvinylpyrrolidone (PVP) were synthesized through 60Co γ ray irradiation, and the swelling ability, pH-sensitivity, gelatine fraction and the absorbing ability of Cr were measured by the Soxhlet extraction device, Uv-vis spectrophotometer and atomic absorption spectrometer, respectively. The result indicates that it is easy to synthesize hydrogels of gelatine/CMC-Na/PVP with monomer mass proportions of 4 : 1 : 2, 4 : 1 : 5 and 2 : 1 : 5 at the absorbed doses of 15, 25, 35 and 45 kGy at the dose rate of 83 Gy/min, respectively. It shows that the swelling behavior of hydrogels becomes different when either the monomer proportion of raw materials or the absorbed doses vary. The swelling ratio (SR) of hydrogels can be up to 56 at pH=7, while the minimal value is 7 at pH=1, which indicates that the SR of hydrogel is sensitive to pH. The hydrogel of PVP will not be degraded after many years, but the hydrogels of gelatine/CMC-Na/PVP will be degraded within one month. It indicates that the degradation of hydrogels can be accelerated as the nature polymer can be degraded into the hydrogels. The adsorptive capacity of Cr(Ⅵ) is up to 0.539 g/g. (authors)

  16. ph Sensitive hydrogel as colon specific drug delivery

    International Nuclear Information System (INIS)

    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.

  17. Printable temperature-responsive hybrid hydrogels with photoluminescent carbon nanodots

    International Nuclear Information System (INIS)

    Smart ink-like hybrid hydrogels that simultaneously possess semi-interpenetrating network structure, strong photoluminescence and temperature sensitivity are successfully fabricated based on the crosslink of poly(acrylamide) (PAAm) in the presence of poly(N-isopropylacrylamide) (PNIPAM) and carbon nanodots (CNDs) at room temperature. The resulting hybrid hydrogels were highly photoluminescent. The photoluminescence was sensitive to external temperature stimuli and reversible. Moreover, the hybrid hydrogels were applied as fluorescent inks for patterning using gravure printing, which may open a door towards developing smart CND based thermosensitive photoluminescent markers and sensors. (paper)

  18. Synthesis and characterization of hydrogel bonded with rare earth

    Institute of Scientific and Technical Information of China (English)

    YAN Changhao; JIAO Lianlian; GUO Chunfang; ZHANG Ming; QIU Guanming

    2008-01-01

    Chitosan-poly(acrylic acid) hydrogel bonded with Eu3+ was prepared by radical solution polymerization. Biodegradable chitosan,N,N'-methylen-diacrylamide, and potassium persulphate were used as the basic material, cross-linking agent, and initiator, respectively. The structure and thermal property of hydrogel were characterized by infrared spectrometry, X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The swollen property and fluorescent performance were also characterized. The results showed that the rare earth presented unique distribution in the hydrogel due to the formation of chemical bonds after polymerization. The glass transition tem-perature of the hydrogel decreased remarkably, which might broaden the range of its elastic application considerably. Moreover, the charac-teristic fluorescent emission of Eu3+ was observed in the hydrogel, which was indicative of the excellent luminescent performance.

  19. Development of sago starch hydrogel for wound dressing

    International Nuclear Information System (INIS)

    Sago starch is utilized in Malaysia mainly for food production. The purpose of the research is to diversify the use of sago starch for medical application particularly in development of hydrogel burn wound dressing. The sago starch is blending with mixture of PVP and PVA to improve the degree of crosslink, mechanical properties, swelling ability and tackiness of the blend hydrogel (sago/PVA and sago PVP). Additives have been introduced into the system such as, polypropylene glycol or carboxymethyl cellulose to improved further the swelling ability and tackiness properties of the blend hydrogel as well as other properties. Effect of irradiation dose on the blend hydrogel has also been studied to optimize the effective dose for blend hydrogel and simultaneously for sterilization purpose. (author)

  20. Development of sago starch hydrogel for wound dressing

    Energy Technology Data Exchange (ETDEWEB)

    Kamaruddin Hashim; Khairul Zaman HJ. Mohd Dahlan; Kamarudin Bahari [Malaysian Institute for Nuclear Technology Research (MINT), Bangi (Malaysia); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2001-03-01

    Sago starch is utilized in Malaysia mainly for food production. The purpose of the research is to diversify the use of sago starch for medical application particularly in development of hydrogel burn wound dressing. The sago starch is blending with mixture of PVP and PVA to improve the degree of crosslink, mechanical properties, swelling ability and tackiness of the blend hydrogel (sago/PVA and sago PVP). Additives have been introduced into the system such as, polypropylene glycol or carboxymethyl cellulose to improved further the swelling ability and tackiness properties of the blend hydrogel as well as other properties. Effect of irradiation dose on the blend hydrogel has also been studied to optimize the effective dose for blend hydrogel and simultaneously for sterilization purpose. (author)

  1. Arct'Alg release from hydrogel membranes

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Renata H.; Rogero, Sizue O.; Shihomatsu, Helena M.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: rhamaral@ipen.br, e-mail: sorogero@ipen.br

    2009-07-01

    The hydrogel properties make them attractive for a variety of biomedical and pharmaceutical applications, primarily in drug delivery system. Synthetic hydrogels have been studied to develop new devices for drugs or cosmetic active agents release. Arct'Alg{sup R} is an extract derived from red algae biomass which has antioxidant, anti-inflammatory and tissue regeneration stimulant properties. This extract was incorporated to poly(N-vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) hydrogel membranes obtained by gamma rays crosslinking technique. The ionizing radiation presents the advantage to occur polymerization and sterilization simultaneously in the same process. The aim of this work was the in vitro release kinetic study of Arct'Alg{sup R} from hydrogel membranes during 24 hours to verify the possibility of use in cosmetic and dermatological treatments. Results showed that about 50% and 30% of incorporated Arct'Alg{sup R} was released from PVP and PVA hydrogel membrane devices respectively. (author)

  2. The design of reversible hydrogels to capture extracellular matrix dynamics

    Science.gov (United States)

    Rosales, Adrianne M.; Anseth, Kristi S.

    2016-02-01

    The extracellular matrix (ECM) is a dynamic environment that constantly provides physical and chemical cues to embedded cells. Much progress has been made in engineering hydrogels that can mimic the ECM, but hydrogel properties are, in general, static. To recapitulate the dynamic nature of the ECM, many reversible chemistries have been incorporated into hydrogels to regulate cell spreading, biochemical ligand presentation and matrix mechanics. For example, emerging trends include the use of molecular photoswitches or biomolecule hybridization to control polymer chain conformation, thereby enabling the modulation of the hydrogel between two states on demand. In addition, many non-covalent, dynamic chemical bonds have found increasing use as hydrogel crosslinkers or tethers for cell signalling molecules. These reversible chemistries will provide greater temporal control of adhered cell behaviour, and they allow for more advanced in vitro models and tissue-engineering scaffolds to direct cell fate.

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

    Science.gov (United States)

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-01

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

  4. Radio-synthesized polyacrylamide hydrogels for proteins release

    International Nuclear Information System (INIS)

    The use of hydrogels for biomedical purposes has been extensively investigated. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release, using papain and bovine serum albumin as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using γ-radiation under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density and evaluated according to protein release, bioactivity and cytotoxicity. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4–5% (w/v) polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties and proteins. This selection was based on the release of the proteins during the experiment period (up to 50 h), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay it was also adequate for biomedical purposes, however this method was not able to generate a matrix with controlled pore sizes. Highlights: • Method for synthesis of polyacrylamide (copolymer) hydrogels using γ-irradiation. • Polyacrylamide hydrogels suitable for protein loading and release. • Controlled release of proteins and bioactivity maintenance. • Noncytotoxic profile observed for these protein containing hydrogels

  5. Injectable shear-thinning nanoengineered hydrogels for stem cell delivery.

    Science.gov (United States)

    Thakur, Ashish; Jaiswal, Manish K; Peak, Charles W; Carrow, James K; Gentry, James; Dolatshahi-Pirouz, Alireza; Gaharwar, Akhilesh K

    2016-06-16

    Injectable hydrogels are investigated for cell encapsulation and delivery as they can shield cells from high shear forces. One of the approaches to obtain injectable hydrogels is to reinforce polymeric networks with high aspect ratio nanoparticles such as two-dimensional (2D) nanomaterials. 2D nanomaterials are an emerging class of ultrathin materials with a high degree of anisotropy and they strongly interact with polymers resulting in the formation of shear-thinning hydrogels. Here, we present 2D nanosilicate reinforced kappa-carrageenan (κCA) hydrogels for cellular delivery. κCA is a natural polysaccharide that resembles native glycosaminoglycans and can form brittle hydrogels via ionic crosslinking. The chemical modification of κCA with photocrosslinkable methacrylate groups renders the formation of a covalently crosslinked network (MκCA). Reinforcing the MκCA with 2D nanosilicates results in shear-thinning characteristics, and enhanced mechanical stiffness, elastomeric properties, and physiological stability. The shear-thinning characteristics of nanocomposite hydrogels are investigated for human mesenchymal stem cell (hMSC) delivery. The hMSCs showed high cell viability after injection and encapsulated cells showed a circular morphology. The proposed shear-thinning nanoengineered hydrogels can be used for cell delivery for cartilage tissue regeneration and 3D bioprinting. PMID:27270567

  6. Injectable shear-thinning nanoengineered hydrogels for stem cell delivery

    Science.gov (United States)

    Thakur, Ashish; Jaiswal, Manish K.; Peak, Charles W.; Carrow, James K.; Gentry, James; Dolatshahi-Pirouz, Alireza; Gaharwar, Akhilesh K.

    2016-06-01

    Injectable hydrogels are investigated for cell encapsulation and delivery as they can shield cells from high shear forces. One of the approaches to obtain injectable hydrogels is to reinforce polymeric networks with high aspect ratio nanoparticles such as two-dimensional (2D) nanomaterials. 2D nanomaterials are an emerging class of ultrathin materials with a high degree of anisotropy and they strongly interact with polymers resulting in the formation of shear-thinning hydrogels. Here, we present 2D nanosilicate reinforced kappa-carrageenan (κCA) hydrogels for cellular delivery. κCA is a natural polysaccharide that resembles native glycosaminoglycans and can form brittle hydrogels via ionic crosslinking. The chemical modification of κCA with photocrosslinkable methacrylate groups renders the formation of a covalently crosslinked network (MκCA). Reinforcing the MκCA with 2D nanosilicates results in shear-thinning characteristics, and enhanced mechanical stiffness, elastomeric properties, and physiological stability. The shear-thinning characteristics of nanocomposite hydrogels are investigated for human mesenchymal stem cell (hMSC) delivery. The hMSCs showed high cell viability after injection and encapsulated cells showed a circular morphology. The proposed shear-thinning nanoengineered hydrogels can be used for cell delivery for cartilage tissue regeneration and 3D bioprinting.

  7. Differential effect of hypoxia on human mesenchymal stem cell chondrogenesis and hypertrophy in hyaluronic acid hydrogels.

    Science.gov (United States)

    Zhu, Meiling; Feng, Qian; Bian, Liming

    2014-03-01

    Photocrosslinked hyaluronic acid (HA) hydrogels provide a conducive 3-D environment that supports the chondrogenesis of human mesenchymal stem cells (hMSCs). The HA macromer concentration in the hydrogels has a significant impact on the chondrogenesis of the encapsulated MSCs due to changes in the physical properties of the hydrogels. Meanwhile, hypoxia has been shown to promote MSC chondrogenesis and suppress subsequent hypertrophy. This study investigates the combinatorial effect of tuning HA macromer concentration (1.5-5%w/v) and hypoxia on MSC chondrogenesis and hypertrophy. To decouple the effect of HA concentration from that of crosslinking density, the HA hydrogel crosslinking density was adjusted by varying the extent of the reaction through the light exposure time while keeping the HA concentration constant (5%w/v at 5 or 15 min). It was found that hypoxia had no significant effect on the chondrogenesis and cartilaginous matrix synthesis of hMSCs under all hydrogel conditions. In contrast, the hypoxia-mediated positive or negative regulation of hMSC hypertrophy in HA hydrogels is dependent on the HA concentration but independent of the crosslinking density. Specifically, hypoxia significantly suppressed hMSC hypertrophy and neocartilage calcification in low HA concentration hydrogels, whereas hypoxia substantially enhanced hMSC hypertrophy, leading to elevated tissue calcification in high HA concentration hydrogels irrespective of their crosslinking density. In addition, at a constant high HA concentration, increasing hydrogel crosslinking density promoted hMSC hypertrophy and matrix calcification. To conclude, the findings from this study demonstrate that the effect of hypoxia on hMSC chondrogenesis and hypertrophy is differentially influenced by the encapsulating HA hydrogel properties. PMID:24342044

  8. Stimulus-responsive hydrogels made from biosynthetic fibrinogen conjugates for tissue engineering: structural characterization.

    Science.gov (United States)

    Frisman, Ilya; Shachaf, Yonatan; Seliktar, Dror; Bianco-Peled, Havazelet

    2011-06-01

    Nanostructured hydrogels based on "smart" polymer conjugates of poloxamers and protein molecules were developed in order to form stimulus-responsive materials with bioactive properties for 3-D cell culture. Functionalized Pluronic F127 was covalently attached to a fibrinopeptide backbone and cross-linked into a structurally versatile and mechanically stable polymer network endowed with bioactivity and temperature-responsive structural features. Small angle X-ray scattering and transmission electron microscopy combined with rheology were used to characterize the structural and mechanical features of this biosynthetic conjugate, both in solution and in hydrogel form. The temperature at which the chemical cross-linking of F127-fibrinopeptide conjugates was initiated had a profound influence on the mechanical properties of the thermo-responsive hydrogel. The analysis of the scattering data revealed modification in the structure of the protein backbone resulting from increases in ambient temperature, whereas the structure of the polymer was not affected by ambient temperature. The hydrogel cross-linking temperature also had a major influence on the modulus of the hydrogel, which was rationally correlated to the molecular structure of the polymer network. The hydrogel structure exhibited a small mesh size when cross-linked at low temperatures and a larger mesh size when cross-linked at higher temperatures. The mesh size was nicely correlated to the mechanical properties of the hydrogels at the respective cross-linking temperatures. The schematic charts that model this material's behavior help to illustrate the relationship that exists between the molecular structure, the cross-linking temperature, and the temperature-responsive features for this class of protein-polymer conjugates. The precise control over structural and mechanical properties that can be achieved with this bioactive hydrogel material is essential in designing a tissue-engineering scaffold for clinical

  9. PVA-Sago starch hydrogel and the preliminary clinical animal study of the hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Kamaruddin; Mohd Dahlan, Khairul Zaman [Malaysian Institute for Nuclear Technology Research, Bangi, Kajang (Malaysia); Halim, Ahmad Sukari; Md Nor, Mohd Tarmizi [Sciences University of Malaysia, School of Medical Sciences, Kerian, Kelantan (Malaysia); Yoshii, Fumio [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2002-03-01

    Sago starch granule dissolves in hot water to form physically crosslink semi-gel structure. Polyvinyl alcohol (PVA) in aqueous solution is chemically crosslink and form hydrogel after expose to gamma or electron beam irradiation. Combination of sago starch and PVA give tremendous improvement on strength and elasticity of the gel. Adding additive such as carboxymethyl cellulose enhance the swelling or absorption property of the gel. These properties of hydrogel are important for wound dressing application. The preliminary clinical animal study on the PVA Sago hydrogel dressing shows promising results of healing process in comparison with the conventional dressing using vaseline impregnated gauze acting as control dressing. This re-confirmed by biopsy tests on the wound tissue taking during the healing process. The tests show the increasing amount of fibroblast and endothelial cells on both wounds using hydrogel and jalonet during the healing process. Also, the rate of epitheliazation is almost completed for both wounds after 10 days of dressing and the lymphocytes cell increase tremendously for the first 14 days with hydrogel dressing. (author)

  10. PVA-Sago starch hydrogel and the preliminary clinical animal study of the hydrogel

    International Nuclear Information System (INIS)

    Sago starch granule dissolves in hot water to form physically crosslink semi-gel structure. Polyvinyl alcohol (PVA) in aqueous solution is chemically crosslink and form hydrogel after expose to gamma or electron beam irradiation. Combination of sago starch and PVA give tremendous improvement on strength and elasticity of the gel. Adding additive such as carboxymethyl cellulose enhance the swelling or absorption property of the gel. These properties of hydrogel are important for wound dressing application. The preliminary clinical animal study on the PVA Sago hydrogel dressing shows promising results of healing process in comparison with the conventional dressing using vaseline impregnated gauze acting as control dressing. This re-confirmed by biopsy tests on the wound tissue taking during the healing process. The tests show the increasing amount of fibroblast and endothelial cells on both wounds using hydrogel and jalonet during the healing process. Also, the rate of epitheliazation is almost completed for both wounds after 10 days of dressing and the lymphocytes cell increase tremendously for the first 14 days with hydrogel dressing. (author)

  11. Redox-active Crosslinkable Poly(ionic liquid)s

    NARCIS (Netherlands)

    Sui, Xiaofeng; Hempenius, Mark A.; Vancso, G. Julius

    2012-01-01

    The synthesis of a new class of cross-linkable redox-responsive poly(ferrocenylsilane)-based poly(ionic liquid)s (PFS-PILs) is reported. PFS-PILs self-cross-link at low concentrations into nanogels or form macroscopic hydrogel networks at higher concentrations. PFS-PILs proved to be efficient disper

  12. HLC/pullulan and pullulan hydrogels: their microstructure, engineering process and biocompatibility.

    Science.gov (United States)

    Li, Xian; Xue, Wenjiao; Liu, Yannan; Li, Weina; Fan, Daidi; Zhu, Chenhui; Wang, Yaoyu

    2016-01-01

    New locally injectable biomaterials that are suitable for use as soft tissue fillers are needed to address a significant unmet medical need. In this study, we used pullulan and human-like collagen (HLC) based hydrogels with various molecular weights (MWs) in combination therapy against tissue defects. Briefly, pullulan was crosslinked with NaIO4 to form a pullulan hydrogel and then may coupled with HLC using the reaction between the -NH2 end-group of HLC and the -CHO group present on the aldehyde pullulan to form the HLC/pullulan hydrogel, wherein the NaIO4 acted as the crosslinking and oxidizing agent. The good miscibility of pullulan and HLC in the hydrogels was confirmed via Fourier transform infrared spectroscopy, scanning electron microscopy, compression testing, enzyme degradation testing, cell adhesions, live/dead staining and subcutaneous filling assays. Here, pullulan hydrogels with various MWs were fabricated and physicochemically characterized. Limitations of the pullulan hydrogels included inflammation, poor mechanical strength, and degradation. By contrast, the properties of the HLC/pullulan hydrogels strongly enhanced. The efficacy of these hydrogels was evaluated both in vitro and in vivo. Our results indicate that HLC/pullulan hydrogels may have therapeutic value as efficient soft tissue fillers, with reduced inflammation, improved cell adhesion and delayed hydrogel degradation. PMID:26478402

  13. Interactions of chitosan/genipin hydrogels during drug delivery: a QSPR approach

    Directory of Open Access Journals (Sweden)

    Nancy L. Delgadillo-Armendariz

    2014-01-01

    Full Text Available A hydrogel comprised of chitosan crosslinked using the low-toxicity crosslinker genipin was prepared, and the absorption of glibenclamide by the hydrogel was investigated. Optimized structures and their molecular electrostatic potentials were calculated using the AM1 method, and the results were used to evaluate the molecular interactions between the three compounds. The quantitative structure-property relationship model was also used to estimate the activity of the chemicals on the basis their molecular structures. In addition, theoretical Fourier transform infrared spectra were calculated to analyze the intermolecular interactions in the proposed system. Finally, the hydrophilicity of the hydrogel and its influence on the absorption process were also estimated.

  14. Radiation polymerization and crosslinking of N-isopropylacrylamide in aqueous solution and in solid state

    International Nuclear Information System (INIS)

    Poly(N-isopropylacrylamide) hydrogels were synthesized by radiation induced simultaneous polymerization and cross-linking. Aqueous monomer solutions and pure monomer, without crosslinker, were irradiated in nitrogen atmosphere at a 60Co gamma source. The conversion from monomer to polymer and cross-linked gel was investigated as a function of temperature and monomer concentration. The swelling behavior of the gels showed clear dependence on the synthesis conditions. (author)

  15. 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)

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

    Science.gov (United States)

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

    2009-03-19

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

  17. Konjac glucomannan/graphene oxide hydrogel with enhanced dyes adsorption capability for methyl blue and methyl orange

    Science.gov (United States)

    Gan, Lu; Shang, Songmin; Hu, Enling; Yuen, Chun Wah Marcus; Jiang, Shou-xiang

    2015-12-01

    In the present study, the graphene oxide (GO) filled konjac glucomannan (KGM) hydrogel was prepared by using calcium oxide as the crosslinker. The structure of the prepared KGM/GO hydrogel was characterized. The prepared hydrogel was then used to adsorb methyl orange (MO) and methyl blue (MB) in aqueous solutions. Due to the presence of GO, KGM/GO hydrogel showed much enhanced adsorbing performance to both MO and MB compared to neat KGM hydrogel. The adsorption kinetics of the hydrogel was studied. The prepared hydrogel fitted for the pseudo-second-order kinetics model better. The adsorption isotherm of the MO and MB onto KGM/GO hydrogel was also studied and the results suggested that the both MO and MB adsorption behaviors fitted for the Freundlich isotherm model better. The prepared KGM/GO has application potentials to be as the adsorbent for water purifications.

  18. Kinetics of Iododeoxyuridine release from sodium alginate hydrogel in vitro

    Institute of Scientific and Technical Information of China (English)

    XU Yong-hua; Mandar R Jagtap; ZHANG Dian-bo; YING Jun; Ronald C McGarry; Marc S. Mendonca; Gordon McLennan

    2006-01-01

    Objective To investigate the kinetics of Iododeoxyuridine (IUdR)release from sodium alginate hydrogel cross-linked with varying amounts of calcium chloride, and to optimize sustained release for further periadventitial I125-labeled IUdR delivery to suppress intimal hyperplasia following angioplasty in vivo.Methods Four hydrogels,composed of 0.16 mEq sodium alginate and 200 g IUdR, were cross-linked with calcium chloride to yield ion equivalence (IE) ratios (Calcium: alginate) of 3:1, 4:1, 5:1, or 6:1. 2 ml of normal saline was placed on top of each hydrogel and allowed to remain in contact at 37℃ for up to 30 days. At set time intervals, the concentration and amount of IUdR in the eluate were assayed by high performance liquid chromatography using UV detection and Water symmetry C18 column. The data for accumulated release rate and concentration in the eluate were calculated based on the calibration curve of peak area versus IUdR concentration. The hydrogel morphologic degradations were also observed. Results The hydrogels entrapped 92.9%, 98.6%, 98.4% and 98.6% of the IUdR with 3:1, 4:1, 5:1 and 6:1 IE ratios, respectively. IUdR concentration in eluates from 3:1 IE ratio hydrogel decreased faster than that from other hydrogels over time (P < 0.01). The 4:1, 5:1 and 6:1 IE ratio hydrogels produced more than 10 μm IUdR concentrations in eluates for the first 8 days, while the 3:1 IE ratio hydrogel for 4 days. IUdR release rates of the 4:1, 5:1 and 6:1 IE ratio hydrogels were very close, however they were lower than that of the 3:1 IE hydrogel in the first 48 hours (P < 0.05). At day 30, the 3:1 and 4:1 IE ratio hydrogels had 100% and 88% degradation, but no significant degradation was observed in the other hydrogels. Conclusion The sodium alginate hydrogel with 4:1 IE ratio exhibited an optimal IUdR sustained release and almost complete degradation in 30 days. (J Intervent Radiol,2006 , 15: 293-298)

  19. Thermosensitive Poly(N-isopropylacrylamide-co-acrylonitrile) Hydrogels with Rapid Response%非离子型凝胶球在水中的溶胀行为

    Institute of Scientific and Technical Information of China (English)

    黄健; 黄志明; 包永忠; 翁志学

    2006-01-01

    Acrylonitrile (AN) was copolymerized with N-isopropylacrylamide (NIPA) to synthesize thermosensitive bydrogels, and the on-off switch behavior of poly(NIPA-co-AN) hydrogels with different fraction of hydrophobic component (AN) was investigated. It is found that the lower critical solution temperature (LCST), the swelling ratio at certain temperature and the reswelling rate of poly(NIPA-co-AN) hydrogels decreased as AN unit fraction in copolymers increased. In order to improve the responsive rate of poly(NIPA-co-AN) hydrogels, they were further treated by surface crosslinking using N, N'-methylene bisacrylamide (BIS) as a crosslinking agent. The swelling and deswelling behaviors of these copolymers were compared with those of the untreated hydrogels. The results indicated that the responsive rate of poly(NIPA-co-AN) hydrogel was improved by surface crosslinking. The resulting hydrogels bearing cyano groups with fast response have potential applications in the field of drug-controlled release and immobilization of biomolecules.

  20. Synthesis and Characterization of Cellulose-Based Hydrogels to Be Used as Gel Electrolytes

    Directory of Open Access Journals (Sweden)

    Maria Assunta Navarra

    2015-11-01

    Full Text Available Cellulose-based hydrogels, obtained by tuned, low-cost synthetic routes, are proposed as convenient gel electrolyte membranes. Hydrogels have been prepared from different types of cellulose by optimized solubilization and crosslinking steps. The obtained gel membranes have been characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical tests in order to investigate the crosslinking occurrence and modifications of cellulose resulting from the synthetic process, morphology of the hydrogels, their thermal stability, and viscoelastic-extensional properties, respectively. Hydrogels liquid uptake capability and ionic conductivity, derived from absorption of aqueous electrolytic solutions, have been evaluated, to assess the successful applicability of the proposed membranes as gel electrolytes for electrochemical devices. To this purpose, the redox behavior of electroactive species entrapped into the hydrogels has been investigated by cyclic voltammetry tests, revealing very high reversibility and ion diffusivity.

  1. Synthesis and Characterization of Poly(N-Vinyl-2-Pyrrolidone/Itaconic Acid) Hydrogel

    Institute of Scientific and Technical Information of China (English)

    郭锦棠; 李伶; 李雄勇; 刘冰

    2004-01-01

    With N-vinyl-2-pyrrolidone (NVP) and itaconic acid(IA), poly(N-vinyl-2-pyrrolidone/itaconic acid)[P(NVP/IA)] hydrogel was synthesized by free radical solution polymerization. The structure of this P(NVP/IA) was characterized by IR. Effects of concentration of itaconic acid, amount of cross-link agent, N,N′-methylene-bis-acrylamide, reaction temperature, and time on properties of swelling ratio(SR) of the hydrogel were investigated.The results show that the best swelling property of the hydrogel is obtained at 50 ℃ and 1.5 h. pH sensitivity increases as the concentration of itaconic acid in the hydrogel system increases. Swelling ratio of the hydrogel decreases as the amount of cross-link agent increases.

  2. Engineering a Dual-Layer Chitosan-Lactide Hydrogel To Create Endothelial Cell Aggregate-Induced Microvascular Networks In Vitro and Increase Blood Perfusion In Vivo.

    Science.gov (United States)

    Kim, Sungwoo; Kawai, Toshiyuki; Wang, Derek; Yang, Yunzhi

    2016-08-01

    Here, we report the use of chemically cross-linked and photo-cross-linked hydrogels to engineer human umbilical vein endothelial cell (HUVEC) aggregate-induced microvascular networks to increase blood perfusion in vivo. First, we studied the effect of chemically cross-linked and photo-cross-linked chitosan-lactide hydrogels on stiffness, degradation rates, and HUVEC behaviors. The photo-cross-linked hydrogel was relatively stiff (E = ∼15 kPa) and possessed more compact networks, denser surface texture, and lower enzymatic degradation rates than the relatively soft, chemically cross-linked hydrogel (E = ∼2 kPa). While both hydrogels exhibited nontoxicity, the soft chemically cross-linked hydrogels expedited the formation of cell aggregates compared to the photo-cross-linked hydrogels. Cells on the less stiff, chemically cross-linked hydrogels expressed more matrix metalloproteinase (MMP) activity than the stiffer, photo-cross-linked hydrogel. This difference in MMP activity resulted in a more dramatic decrease in mechanical stiffness after 3 days of incubation for the chemically cross-linked hydrogel, as compared to the photo-cross-linked one. After determining the physical and biological properties of each hydrogel, we accordingly engineered a dual-layer hydrogel construct consisting of the relatively soft, chemically cross-linked hydrogel layer for HUVEC encapsulation, and the relatively stiff, acellular, photo-cross-linked hydrogel for retention of cell-laden microvasculature above. This dual-layer hydrogel construct enabled a lasting HUVEC aggregate-induced microvascular network due to the combination of stable substrate, enriched cell adhesion molecules, and extracellular matrix proteins. We tested the dual-layer hydrogel construct in a mouse model of hind-limb ischemia, where the HUVEC aggregate-induced microvascular networks significantly enhanced blood perfusion rate to ischemic legs and decreased tissue necrosis compared with both no treatment and

  3. The design of conductimetric biosensors based on environmentally responsive hydrogels

    Science.gov (United States)

    Lesho, Matthew Jerome

    Responsive hydrogels are hydrophilic, crosslinked polymers that undergo large changes in hydration in response to environmental stimuli such as changing temperature, pH, electric field, and ionic strength. Accompanying this change in hydration are changes in material properties of the hydrogel, which has led to their application in controlled drug delivery, separations, and as superabsorbants. The present study investigated the hydration-dependent electrical conductivity of a pH-responsive hydrogel and its application as a transduction layer for microfabricated, conductimetric pH and glucose sensors. The investigation was divided into four parts. First, the material properties of a copolymer of 2-hydroxyethyl methacrylate (HEMA) and N,N-dimethylaminoethyl methacrylate (DMA), crosslinked with tetraethylene glycol diacrylate (TEGDA), were examined with respect to its ability to detect changes in pH. It was determined that the electrical conductivity of the hydrogel was a sensitive measure of hydration and was a function of pH, hydrogel composition, buffer concentration, buffer identity, and ionic strength. Second, a method was developed for reproducibly depositing thin (1-25 mum), adherent hydrogel layers by photolithographic patterning techniques. Third, sensors were developed that utilized planar interdigitated electrode arrays to probe the change in electrical conductivity of hydrogel membranes. The sensitivity, response time, operating range and lifetime of pH sensors were functions of pH, hydrogel composition, buffer concentration, buffer identity, and ionic strength. Glucose sensors were developed by incorporating glucose oxidase into the pH-responsive hydrogel and measuring the decrease in pH that accompanies the enzymatic generation of protons. Finally, a model was formulated to relate the measured sensor responses to the measured material properties. Information from model simulations was incorporated into the design of next-generation sensors.

  4. Anti-inflammatory drug delivery from hyaluronic acid hydrogels.

    Science.gov (United States)

    Hahn, Sei K; Jelacic, Sandra; Maier, Ronald V; Stayton, Patrick S; Hoffman, Allan S

    2004-01-01

    Two different types of hyaluronic acid (HA) hydrogels were synthesized by crosslinking HA with divinyl sulfone (DVS) and poly(ethylene glycol)-divinyl sulfone (VS-PEG-VS). Vitamin E succinate (VES), an anti-inflammatory drug, and bovine serum albumin (BSA), a model of anti-inflammatory protein drugs, were loaded into the gels and their release kinetics were measured in vitro. VES and BSA released with a burst from both HA hydrogels during the first few hours, and release continued gradually for several days. The rate of release from HA-VS-PEG-VS-HA hydrogels was faster than that from HA-DVS-HA hydrogels, presumably due to the lower crosslink density in the former. The anti-inflammatory action of released VES was tested by incubating peripheral blood mononuclear cells (PBMC) on HA hydrogels with and without VES in the gel. The number of cells adhering on HA hydrogels was very low compared to that on tissue culture polystyrene (TCPS), which might be one of the important advantages of using HA hydrogels for implant coatings or tissue engineering applications. ELISA test results showed that the tumor necrosis factor-alpha (TNF-alpha) concentration was very low in the supernatant of the wells containing the HA hydrogel with VES in contact with the activated macrophages compared to that without VES. This is probably the effect of the released VES reducing the production of anti-inflammatory cytokine, TNF-alpha. HA hydrogels containing anti-inflammatory drugs may have potential for use in tissue engineering and also as biocompatible coatings of implants. PMID:15503629

  5. PRAGMATIC HYDROGELS

    OpenAIRE

    Patil S.A.; Rane B.R.; Bakliwal S.R.; Pawar S.P.

    2011-01-01

    Man has always been plagued with many ailments and diseases. The field of pharmaceutical science has today become more invaluable in helping to keep us healthy and prevent disease. The availability of large molecular weight protein and peptide-based drugs due to the recent advances has given us a new ways to treat a number of diseases. I wish to present new and promising techniques for the production of drug and protein delivery formulations that have been developed that is Hydrogel. These ar...

  6. Radiation preparation and swelling behavior of sodium carboxymethyl cellulose hydrogels

    International Nuclear Information System (INIS)

    Sodium carboxymethyl cellulose (CMC) is a kind of degraded polymer under γ-irradiation. However, in this work, it has been found that CMC crosslinks partially to form hydrogel by radiation technique at more than 20% CMC aqueous solution. The gel fraction increases with the dose. The crosslinking reaction of CMC is promoted in the presence of N2 or N2O due to the increase of free radicals on CMC backbone, but gel fraction of CMC hydrogel is not high (g, number average molecular weight of network Mc were calculated according to the Charlesby-Pinner equation. The results indicated that although crosslinked CMC hydrogel could be prepared by radiation method, the rate of radiation degradation of CMC was faster than that of radiation crosslinking due to the character of CMC itself. Swelling dynamics of CMC hydrogel and its swelling behavior at different conditions, such as acidic, basic, inorganic salt as well as temperature were also investigated. Strong acidity, strong basicity, small amount of inorganic salts and lower temperature can reduce swelling ratio

  7. Gelatin-Pectin Composite Films from Polyion Complex Hydrogels

    Science.gov (United States)

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

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

    International Nuclear Information System (INIS)

    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

  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. Injectable pullulan hydrogel for the prevention of postoperative tissue adhesion.

    Science.gov (United States)

    Bang, Sumi; Lee, Eungjae; Ko, Young-Gwang; Kim, Won Il; Kwon, Oh Hyeong

    2016-06-01

    Methods for reducing and preventing postoperative abdominal adhesions have been researched for decades; however, despite these efforts, the formation of postoperative peritoneal adhesions is continuously reported. Adhesions cause serious complications such as postoperative pain, intestinal obstruction, and infertility. Tissue adhesion barriers have been developed as films, membranes, knits, sprays, and hydrogels. Hydrogels have several advantages when used as adhesion barriers, including flexibility, low tissue adhesiveness, biodegradability, and non-toxic degraded products. Furthermore, compared with preformed hydrogels, injectable hydrogels can fill and cover spaces of any shape and do not require a surgical procedure for implantation. In this study, pullulan was modified through reaction with 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) to introduce carboxyl and phenyl groups as crosslinking sites. The grafting of tyramine on pullulan allows crosslinking branches on pullulan backbone. We successfully fabricated pullulan hydrogel with an enzymatic reaction using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The chemical structure of modified pullulan was analyzed with ATR-FTIR and (1)H NMR spectroscopies. Rheological properties were tested by measuring storage modulus with varying H2O2, HRP, polymer solution concentrations and tyramine substitution rates. Cell viability and animal tests were performed. The modified pullulan hydrogel is an invaluable advance in anti-adhesion agents. PMID:26879910

  11. Dynamic mechanical and swelling properties of maleated hyaluronic acid hydrogels.

    Science.gov (United States)

    Lin, Hai; Liu, Jun; Zhang, Kai; Fan, Yujiang; Zhang, Xingdong

    2015-06-01

    A series of maleated hyaluronan (MaHA) are developed by modification with maleic anhydride. The degrees of substitution (DS) of MaHA vary between 7% and 75%. The DS of MaHA is both higher and wider than methacrylated HA derivatives (MeHA) reported in the literature. MaHA hydrogels are then prepared by photopolymerization and their dynamic mechanical and swelling properties of the hydrogels are investigated. The results showed that MaHA hydrogels with moderate DS (25%, 50% and 65%) have higher storage modulus and lower equilibrium swelling ratios than those with either low or high DS (7%, 15% and 75%). Theoretical analyses also suggest a similar pattern among hydrogels with different DS. The results confirm that the increased cross-linking density enhances the strength of hydrogels. Meanwhile, the hydrophilicity of introduced groups during modification and the degree of incomplete crosslinking reaction might have negative impact on the mechanical and swelling properties of MaHA hydrogels. PMID:25843871

  12. Synthesis of hydrogels by radiation and their applications in Korea

    International Nuclear Information System (INIS)

    The radiation can induce chemical reaction to modify polymer under even the solid state or in the low temperature. The radiation crosslinking can be easily adjusted by controlling the radiation dose and is reproducible. The finished product contains no residuals of substances required to initiate the chemical crosslinking which can restrict the application possibilities. In these studies, hydrogels from a mixture of poly(N-vinyl pyrrolidone) (PVP), Carrageenan, poly(ethylene glycol) (PEG) and antibacterial agent were made by γ-rays irradiation for wound dressing. The physical properties such as gelation, water absorbability and gel strength were examined to evaluate the hydrogels for wound dressing. The applications of hydrogels in Korea were described. (author)

  13. Poly(ethylene glycol) Hydrogels formed by Thiol-Ene Photopolymerization for Enzyme-Responsive Protein Delivery

    OpenAIRE

    Aimetti, Alex A.; Machen, Alexandra J.; Anseth, Kristi S.

    2009-01-01

    Degradable hydrogels have been extensively used in biomedical applications such as drug delivery, and recent interest has grown in hydrogels that degrade in recognition of a cellular response. This contribution describes a poly(ethylene glycol) (PEG) hydrogel platform with human neutrophil elastase (HNE) sensitive peptide cross-links formed using thiol-ene photopolymerization rendering the gel degradable at sites of inflammation. Further, protein therapeutics can be physically entrapped withi...

  14. Development and in vivo evaluation of silver sulfadiazine loaded hydrogel consisting polyvinyl alcohol and chitosan for severe burns

    OpenAIRE

    S R Chakavala; Patel, N. G.; N VI Pate; Thakkar, V. T.; Patel, K V; Gandhi, T. R.

    2012-01-01

    A new Hydrogel containing silver Sulfadiazine (SSD) was developed for enhanced burns wound healing. The hydrogel was prepared by cross-linking of PVA and Chitosan by freeze thawing method. Their gel properties, moisture retaining capacity, fluid uptake capacity, in vitro release study, in vivo burn healing effect were evaluated. Chitosan and PVA cross linking decreased gel fraction upto 70% determined the good gel properties. This cross linked hydrogel increased the Swelling ratio and Water v...

  15. Mechanical Behavior of Tough Hydrogels for Structural Applications

    Science.gov (United States)

    Illeperuma, Widusha Ruwangi Kaushalya

    Hydrogels are widely used in many commercial products including Jell-O, contact lenses, and superabsorbent diapers. In recent decades, hydrogels have been under intense development for biomedical applications, such as scaffolds in tissue engineering, carriers for drug delivery, and valves in microfluidic systems. But the scope is severely limited as conventional hydrogels are weak and brittle and are not very stretchable. This thesis investigates the approaches that enhance the mechanical properties of hydrogels and their structural applications. We discov¬ered a class of exceptionally stretchable and tough hydrogels made from poly-mers that form networks via ionic and covalent crosslinks. Although such a hydrogel contains ~90% water, it can be stretched beyond 20 times its initial length, and has a fracture energy of ~9000 J/m2. The combination of large stretchability, remarkable toughness, and recoverability of stiffness and toughness, along with easy synthesis makes this material much superior over existing hydrogels. Extreme stretchability and blunted crack tips of these hydrogels question the validity of traditional fracture testing methods. We re-examine a widely used pure shear test method to measure the fracture energy. With the experimental and simulation results, we conclude that the pure shear test method can be used to measure fracture energy of extremely stretchable materials. Even though polyacrylamide-alginate hydrogels have an extremely high toughness, it has a relatively low stiffness and strength. We improved the stiffness and strength by embedding fibers. Most hydrogels are brittle, allowing the fibers to cut through the hydrogel when the composite is loaded. But tough hydrogel composites do not fail by the fibers cutting the hydrogel; instead, it undergoes large deforming by fibers sliding through the matrix. Hydrogels were not considered as materials for structural applications. But with enhanced mechanical properties, they have opened up

  16. 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.

  17. Poly(ethylene glycol)-based thiol-ene hydrogel coatings: curing chemistry, aqueous stability, and potential marine antifouling applications

    NARCIS (Netherlands)

    Lundberg, P.; Bruin, A.; Klijnstra, J.W.; Nyström, A.M.; Johansson, M.; Malkoch, M.; Hult, A.

    2010-01-01

    Photocured thiol-ene hydrogel coatings based on poly(ethylene glycol) (PEG) were investigated for marine antifouling purposes. By varying the PEG length, vinylic end-group, and thiol cross-linker, a library of hydrogel coatings with different structural composition was efficiently accomplished, with

  18. Digital Drug Dosing: Dosing in Drug Assays by Light-Defined Volumes of Hydrogels with Embedded Drug-Loaded Nanoparticles

    DEFF Research Database (Denmark)

    Faralli, Adele; Melander, Fredrik; Larsen, Esben Kjær Unmack;

    2014-01-01

    Polyethylene glycol (PEG)-based hydrogels are widely used for biomedical applications, including matrices for controlled drug release. We present a method for defining drug dosing in screening assays by light-activated cross-linking of PEG-diacrylate hydrogels with embedded drug-loaded liposome n...

  19. Radiation synthesis and characterization of nanosilver/gelatin/carboxymethyl chitosan hydrogel

    International Nuclear Information System (INIS)

    A series of antibacterial hydrogels were fabricated from an aqueous solution of AgNO3, gelatin and carboxymethyl chitosan (CM-chitosan) by radiation-induced reduction and crosslinking at ambient temperature. The nanosilver particles were in situ synthesized accompanying with the formation of gelatin/CM-chitosan hydrogel. Transmission Electron Microscope and UV–vis analysis have verified the formation and homogeneous distribution of nanosilver particles in the hydrogel matrix. The nanosilver/gelatin/CM-chitosan hydrogels possessed interconnected porous structure, had a compressive modulus of 44 to 56 kPa, and could absorb 62 to 108 times of deionized water to its dry weight. Furthermore, the hydrogels were found to have sound antibacterial effect on Escherichia coli (E. coli), and their antibacterial ability could be significantly enhanced by the increasing of AgNO3 content. The comprehensive results of this study suggest that nanosilver/gelatin/CM-chitosan hydrogels have potential as an antibacterial wound dressing. - Highlights: ► Nanosilver/gelatin/CM-chitosan hydrogel was synthesized by radiation crosslinking. ► Nanosilver particles distributed homogeneously in the hydrogel. ► The size of nanosilver increased with the increase of AgNO3 concentration. ► The nanosilver/gelatin/CM-chitosan hydrogel has antibacterial ability.

  20. Thermo-sensitive and photoluminescent hydrogels: Synthesis, characterization, and their drug-release property

    International Nuclear Information System (INIS)

    Multifunctional hydrogels that simultaneously possess semi-interpenetrating networks structure, strong photoluminescence, and temperature sensitivity were successfully fabricated based on the crosslink of poly(acrylamide) (PAAm) in the presence of poly(N-isopropylacrylamide) (PNIPAM) and CdTe quantum dots (QDs) at a mild condition. With the increase of external temperature, the photoluminescence (PL) intensity and emission peak of the hydrogels gradually decreased and red-shifted, respectively. Decreasing the temperature, the PL intensity and emission peak of the hydrogels could back to their initial values again. Moreover, drug-release experiments on the multifunctional hydrogels demonstrated that the release rate can be tuned by the environmental temperature and the content of PNIPAM. In addition, biocompatible hyperbranched polyglycerol functionalized QDs (QD-HPGs) instead of pristine QDs can also be incorporated into the hydrogels, affording biocompatible hydrogels which could still exhibit temperature-sensitive photoluminescence and drug-release behaviors. Highlights: → Multifunctional hydrogels that simultaneously possess semi-interpenetrating networks structure, strong photoluminescence, and thermo-sensitive optical and drug-release behaviors were presented for the first time. → These multifunctional hydrogels can be facilely fabricated through the crosslink of poly(acrylamide) in the presence of poly(N-isopropylacrylamide) and CdTe quantum dots at a mild condition. → It is believed that the multifunctional hydrogels will find potential applications in thermo-sensitive devices and drug delivery.

  1. PVNO-DVB hydrogels: synthesis and characterization

    International Nuclear Information System (INIS)

    Hydrogels with various degrees of crosslinking were synthesized from 2-vinylpyridine and divinylbenzene/ethylbenzene monomers using gamma irradiation. The influence of the solvent solubility parameter, ionic strength, and temperature on swelling and gel density were studied. Adsorption of water vapor on these gels was determined, and the data were used in the calculation of free energy changes involved in the process. Finally the drug release behavior-crosslink content relation was investigated. It was found that increase in crosslinking agent content adversely influenced swelling, gel density, and water vapor adsorption. The solvent solubility parameter was found to influence swelling more than ionic strength. Contrary to what was expected, it was not possible to classify the drug release behavior as first order

  2. Hydrogel Actuation by Electric Field Driven Effects

    Science.gov (United States)

    Morales, Daniel Humphrey

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

  3. Radiation formation of hydrogels for biomedical application

    International Nuclear Information System (INIS)

    Hydrogels, i.e. materials consisting of a permanent, three-dimensional network of hydrophilic polymers and water filling the space between the polymer chains, have a number of biomedical applications, such as wound care products, dental and ophthalmic materials, drug delivery systems, elements of implants, constituents of hybrid-type organs, as well as stimuli-sensitive systems. Among various methods applied for the production of hydrogels, the radiation technique has many advantages, as a simple, efficient, clean and environment-friendly process. It usually allows to combine the synthesis and sterilization in a single technological step, thus reducing costs and production time. Efficient application and further development of this method requires broadening of the basic knowledge on the underlying radiation chemistry of polymer systems. Some selected aspects of radiation chemistry of polymers in aqueous solution are presented in this work. The experimental techniques used for studying the radiation-induced processes in polymer solutions are described with special emphasizing of determination of radiation yield of crosslinking by various methods. Also, pulse radiolysis method with different detection methods is briefly described. Selected results of our studies concerning the early stages of polymerization of water-soluble monomers are described together with the studies of mechanisms of radiation-induced crosslinking of polymers in aqueous solution. Separate section of the presentation is devoted to the radiation-induced crosslinking and degradation of polyelectrolytes (i.e. poly (poly (acrylic acid), poly (poly (methacrylic acid)) and biologically important polysaccharide, chitosan. Additionally, special attention is paid to the differences between intra- and intermolecular crosslinking. The irradiation method of changing the proportion between these two processes at the expense on intramolecular crosslinking is described. This leads to the synthesis of

  4. Glucantime drug delivery comparison between crosslinked membranes irradiation versus esterification

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Maria J.A.; Parra, Duclerc F.; Lugao, Ademar B., E-mail: mariajhho@yahoo.com.b, E-mail: dfparra@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Centro de Quimica e Meio Ambiente (CQMA); Amato, Valdir S. [Hospital das Clinicas (HC/USP), Sao Paulo, SP (Brazil). Div. de Clinica de Molestias Infecciosas e Parasitarias

    2009-07-01

    Pentavalent Antimony (Glucantime) is the drug of choice for the treatment of Leishmaniasis. The disease is transmitted by the female bite of Phlebotomine sandflies. The sandflies inject the infective stage, metacyclic promastigotes, during blood meals. The protozoan parasite causes a spectrum of clinical diseases afflicting 12 million people worldwide. The use of hydrogels matrices for particular drug-release applications has been investigated with the synthesis of modified polymeric hydrogel of poly (vinyl alcohol) (PVAl), poly (N-viny-2- pyrrolidone) (PVP) and poly (ethylene glycol). They were processed using gamma radiation from Cobalt-60 source at 25 kGy dose. The characterization of the hydrogels was conducted and toxicity was evaluated. The dried hydrogel was analyzed for differential scanning calorimetry (DSC), thermogravimetry (TGA), swelling and gel content determinations. The membranes have no toxicity and gel content has revealed the crosslink degree. The chemical crosslinking depends on the acid concentration. Increase of the acid concentration increases the gel content, the thermal stability of the PVAl component and decreases the swelling capacity. The thermal stability of irradiated membranes is decreased in the presence of plasticizer. In contrast to ionizing radiation membranes described in the literature and formulated with PVAl/PEG, our new membranes composed by PVAl/PVP/PEG are more flexible and presents higher swelling capacity. The drug was immobilized in the hydrogels structures and the glucantime drug delivery was determined. (author)

  5. Glucantime drug delivery comparison between crosslinked membranes irradiation versus esterification

    International Nuclear Information System (INIS)

    Pentavalent Antimony (Glucantime) is the drug of choice for the treatment of Leishmaniasis. The disease is transmitted by the female bite of Phlebotomine sandflies. The sandflies inject the infective stage, metacyclic promastigotes, during blood meals. The protozoan parasite causes a spectrum of clinical diseases afflicting 12 million people worldwide. The use of hydrogels matrices for particular drug-release applications has been investigated with the synthesis of modified polymeric hydrogel of poly (vinyl alcohol) (PVAl), poly (N-viny-2- pyrrolidone) (PVP) and poly (ethylene glycol). They were processed using gamma radiation from Cobalt-60 source at 25 kGy dose. The characterization of the hydrogels was conducted and toxicity was evaluated. The dried hydrogel was analyzed for differential scanning calorimetry (DSC), thermogravimetry (TGA), swelling and gel content determinations. The membranes have no toxicity and gel content has revealed the crosslink degree. The chemical crosslinking depends on the acid concentration. Increase of the acid concentration increases the gel content, the thermal stability of the PVAl component and decreases the swelling capacity. The thermal stability of irradiated membranes is decreased in the presence of plasticizer. In contrast to ionizing radiation membranes described in the literature and formulated with PVAl/PEG, our new membranes composed by PVAl/PVP/PEG are more flexible and presents higher swelling capacity. The drug was immobilized in the hydrogels structures and the glucantime drug delivery was determined. (author)

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

    International Nuclear Information System (INIS)

    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)

  7. Dendrimers and Dendrons as Versatile Building Blocks for the Fabrication of Functional Hydrogels

    Directory of Open Access Journals (Sweden)

    Sadik Kaga

    2016-04-01

    Full Text Available Hydrogels have emerged as a versatile class of polymeric materials with a wide range of applications in biomedical sciences. The judicious choice of hydrogel precursors allows one to introduce the necessary attributes to these materials that dictate their performance towards intended applications. Traditionally, hydrogels were fabricated using either polymerization of monomers or through crosslinking of polymers. In recent years, dendrimers and dendrons have been employed as well-defined building blocks in these materials. The multivalent and multifunctional nature of dendritic constructs offers advantages in either formulation or the physical and chemical properties of the obtained hydrogels. This review highlights various approaches utilized for the fabrication of hydrogels using well-defined dendrimers, dendrons and their polymeric conjugates. Examples from recent literature are chosen to illustrate the wide variety of hydrogels that have been designed using dendrimer- and dendron-based building blocks for applications, such as sensing, drug delivery and tissue engineering.

  8. Synthesis and Drug Release Properties of Thermosensitive Poly(N-vinylacetamide-co-vinylacctate) Hydrogels

    Institute of Scientific and Technical Information of China (English)

    YANG Li-he; CHU Hong; CHEN Ming-qing; HU Na; ZHAO Yi-fan

    2011-01-01

    Thermosensitive poly[N-vinylacetamide-co-vinylacetate][P(NVA-co-VAc)] hydrogels were prepared via free radical copolymerization from hydrophilic NVA and hydrophobic VAc in the presence of butylenes-bis (N-vinylacetamide)(Bis-NVA) as crosslinker. Scanning electron microscopy(SEM) images reveal that the as-prepared hydrogels were of three-dimensional network with irregular cave structure. The prepared hydrogels with more NVA in the feed swelled faster and the swelling ratio of the hydrogels gradually decreased with temperature increasing from 10 ℃ to 60 ℃. The dynamic swelling studies indicate that the swelling process of the hydrogels was controlled by diffusion of water molecules considered as Fickian-controlled case. The adsorption amount of model drug, sodium salicylate(SS) was higher in the hydrogels containing more NVA units, whose corresponding release could reach equilibrium in about 6 h.

  9. Radiochemical preparation of PAAM hydrogels and their usage in agriculture

    International Nuclear Information System (INIS)

    The polyacrylamide (PAAm) hydrogels are crosslinked polymers and have the interesting ability to release the retained additives to the surrounding media in a controlled manner. This property in turn may have application in agriculture (fertilizers, pesticides) or in medicine, etc. In this study PAAm aqueous solutions were irradiated by varying doses to find the optimum gelation dose and to investigate the following: 1. Radiation induced crosslinking of PAAm. 2. Effect of additives' concentration on the degree of crosslinking. 3. Measurement of the release rate of the additives (pesticides, microelements) versus different soil type and the gel granule size. The results show that the release rate of the additives is not a function of soil type but it rather depends on the background moisture content as well as on the hydrogel particle size. (author)

  10. Structure-property-function relationships in triple helical collagen hydrogels

    CERN Document Server

    Tronci, Giuseppe; Russell, Stephen J; Wood, David J

    2012-01-01

    In order to establish defined biomimetic systems, type I collagen was functionalised with 1,3-Phenylenediacetic acid (Ph) as aromatic, bifunctional segment. Following investigation on molecular organization and macroscopic properties, material functionalities, i.e. degradability and bioactivity, were addressed, aiming at elucidating the potential of this collagen system as mineralization template. Functionalised collagen hydrogels demonstrated a preserved triple helix conformation. Decreased swelling ratio and increased thermo-mechanical properties were observed in comparison to state-of-the-art carbodiimide (EDC)-crosslinked collagen controls. Ph-crosslinked samples displayed no optical damage and only a slight mass decrease (~ 4 wt.-%) following 1-week incubation in simulated body fluid (SBF), while nearly 50 wt.-% degradation was observed in EDC-crosslinked collagen. SEM/EDS revealed amorphous mineral deposition, whereby increased calcium phosphate ratio was suggested in hydrogels with increased Ph content...

  11. Radiochemical preparation of polyacrylamide hydrogels and their use in agriculture

    International Nuclear Information System (INIS)

    In this work, the results of synthesis of hydrogels is presented. These crosslinked polymers have the interesting property that they may release the retained additives to the surrounding media in a controlled manner. This property in turn may have application in agriculture (fertilizers, pesticides) or in medicine etc. In this work aqueous solutions of Polyacrylamide (PAAm) were irradiated to varying doses and concentrations of PAAm to find the optimum gelation dose. Specifically, the following objectives were studied in this work: Radiation induced crosslinking of PAAm; effect of the concentration of additives on the degree of crosslinking; measurement of the release rate of the additives (pesticides microelements) versus different soil type and the gel granule size. The results of this work show that the release rate of the additives is not a function of the soil type, but rather it does depend on the background moisture content, as well as the hydrogel particle size. (author). 7 refs, 11 figs

  12. Photonic hydrogel beads for controlled release of risedronate

    Science.gov (United States)

    Khajuria, Deepak K.; Roy Mahapatra, D.

    2014-03-01

    pH-sensitive photonic composite hydrogel beads composed of sodium alginate and risedronate sodium (SA/RIS) was prepared crosslinked by Ca2+ owing to the ionic gelation of SA. The structure and surface morphology of the composite hydrogel beads were characterized by SEM. pH-sensitivity of these composite hydrogels beads and the release behaviors of drug from them were investigated. The results showed that the composite hydrogel beads had good pH-sensitivity. The drug loading and encapsulation efficiency were 27.7% and 92% for RIS, respectively. The cumulative release ratios of RIS from the composite hydrogel beads were 2.47% in pH 2.1 solution and 83 % in pH 6.8 solutions within 24 h, respectively. However, the cumulative release ratio of RIS in pH 7.4 solution reached 91% within 7 h. It is proposed that the novel photonic SA/RIS composite hydrogel bead could possess the potential of an increased intestinal absorption and fewer adverse effects of RIS. The pH and salt response of photonic hydrogel bead, as well as the encapsulation of macromolecules, are promising for applications in biomedicine and biotechnology.

  13. Multiscale Surface-Attached Hydrogel Thin Films with Tailored Architecture.

    Science.gov (United States)

    Chollet, Benjamin; Li, Mengxing; Martwong, Ekkachai; Bresson, Bruno; Fretigny, Christian; Tabeling, Patrick; Tran, Yvette

    2016-05-11

    A facile route for the fabrication of surface-attached hydrogel thin films with well-controlled chemistry and tailored architecture on wide range of thickness from nanometers to micrometers is reported. The synthesis, which consists in cross-linking and grafting the preformed and ene-reactive polymer chains through thiol-ene click chemistry, has the main advantage of being well-controlled without the addition of initiators. As thiol-ene click reaction can be selectively activated by UV-irradiation (in addition to thermal heating), micropatterned hydrogel films are easily synthesized. The versatility of our approach is illustrated by the possibility to fabricate various chemical polymer networks, like stimuli-responsive hydrogels, on various solid substrates, such as silicon wafers, glass, and gold surfaces. Another attractive feature is the development of new complex hydrogel films with targeted architecture. The fabrication of various architectures for polymer films is demonstrated: multilayer hydrogel films in which single-networks are stacked one onto the other, interpenetrating networks films with mixture of two networks in the same layer, and nanocomposite hydrogel films where nanoparticles are stably trapped inside the mesh of the network. Thanks to its simplicity and its versatility this novel approach to surface-attached hydrogel films should have a strong impact in the area of polymer coatings. PMID:27008162

  14. Synthesis and characterization of antibacterial carboxymethyl Chitosan/ZnO nanocomposite hydrogels.

    Science.gov (United States)

    Wahid, Fazli; Yin, Jun-Jiao; Xue, Dong-Dong; Xue, Han; Lu, Yu-Shi; Zhong, Cheng; Chu, Li-Qiang

    2016-07-01

    The antibacterial carboxymethyl chitosan/ZnO nanocomposite hydrogels were successfully prepared via in situ formation of ZnO nanorods in the crosslinked carboxymethyl chitosan (CMCh) matrix, by treating the CMCh hydrogel matrix with zinc nitrate solution followed by the oxidation of zinc ions with alkaline solution. The resulting CMCh/ZnO hydrogels were characterized by using FTIR spectroscopy, X-ray diffractormetry and scanning electron microscopy (SEM). SEM micrographs revealed the formation of ZnO nanorods in the hydrogel matrix with the size ranging from 190nm to 600nm. The swelling behavior of the prepared nanocomposite hydrogels was also investigated in different pH solutions. The CMCh/ZnO nanocomposite hydrogel showed rather higher swelling behavior in different pH solutions in comparison with neat CMCh hydrogel. Furthermore, the antibacterial activity of CMCh/ZnO hydrogel was studied against Escherichia coli and Staphylococcus aureus by CFU assay. The results demonstrated an excellent antibacterial activity of the nanocomposite hydrogel. Therefore, the developed CMCh/ZnO nanocomposite hydrogel can be used effectively in biomedical field. PMID:27017980

  15. Sea Cucumber-Inspired Autolytic Hydrogels Exhibiting Tunable High Mechanical Performances, Repairability, and Reusability.

    Science.gov (United States)

    Gao, Fei; Zhang, Yinyu; Li, Yongmao; Xu, Bing; Cao, Zhiqiang; Liu, Wenguang

    2016-04-13

    Inspired by stimuli-responsive remarkable changes in consistency (hardening, softening, autolysis) of sea cucumbers, we synthesized a supramolecular polymer(SP) hydrogel directly by photoinitiated aqueous polymerization of N-acryloyl 2-glycine monomer bearing one amide and one carboxyl group on the side chain. The SP hydrogels doped with Ca(2+) demonstrated excellent mechanical properties-high tensile strength (∼1.3 MPa), large stretchability (up to 2300%), high compressive strength (∼10.8 MPa), and good toughness (∼1000 J m(-2)) due to cooperative hydrogen bonding interactions from amide and carboxyl together with Ca(2+) cross-linking. Responding to the change in pH and Ca(2+) concentration, the hydrogels could modulate their network stability and mechanical properties: at pH3.0 and higher Ca(2+) content, the hydrogel formed low swelling network which was stiff and stable; in alkaline or neutral buffer with lower content of or without Ca(2+), the hydrogel formed a highly swollen transient network, which was soft and eventually autolyzed. The reversible multiple noncovalent bonds enabled the hydrogels to achieve thermoplasticity, self-healability, and reusability. Notably, distinct formulations of hydrogels could be welded together under heating to form a gradient hydrogel. In vitro cytotoxicity assay and subcutaneous implantation indicated that the SP hydrogels were biocompatible and autolytic in vivo. The SP hydrogels may find applications as temporary biodevices for intestinal drug delivery or for injectable filling in assisting suturing small vessels. PMID:27014865

  16. Gelatin- and starch-based hydrogels. Part A: Hydrogel development, characterization and coating.

    Science.gov (United States)

    Van Nieuwenhove, Ine; Salamon, Achim; Peters, Kirsten; Graulus, Geert-Jan; Martins, José C; Frankel, Daniel; Kersemans, Ken; De Vos, Filip; Van Vlierberghe, Sandra; Dubruel, Peter

    2016-11-01

    The present work aims at constructing the ideal scaffold matrix of which the physico-chemical properties can be altered according to the targeted tissue regeneration application. Ideally, this scaffold should resemble the natural extracellular matrix (ECM) as close as possible both in terms of chemical composition and mechanical properties. Therefore, hydrogel films were developed consisting of methacrylamide-modified gelatin and starch-pentenoate building blocks because the ECM can be considered as a crosslinked hydrogel network consisting of both polysaccharides and structural, signaling and cell-adhesive proteins. For the gelatin hydrogels, three different substitution degrees were evaluated including 31%, 72% and 95%. A substitution degree of 32% was applied for the starch-pentenoate building block. Pure gelatin hydrogels films as well as interpenetrating networks with gelatin and starch were developed. Subsequently, these films were characterized using gel fraction and swelling experiments, high resolution-magic angle spinning (1)H NMR spectroscopy, rheology, infrared mapping and atomic force microscopy. The results indicate that both the mechanical properties and the swelling extent of the developed hydrogel films can be controlled by varying the chemical composition and the degree of substitution of the methacrylamide-modified gelatin applied. The storage moduli of the developed materials ranged between 14 and 63kPa. Phase separation was observed for the IPNs for which separated starch domains could be distinguished located in the surrounding gelatin matrix. Furthermore, we evaluated the affinity of aggrecan for gelatin by atomic force microscopy and radiolabeling experiments. We found that aggrecan can be applied as a bioactive coating for gelatin hydrogels by a straightforward physisorption procedure. Thus, we achieved distinct fine-tuning of the physico-chemical properties of these hydrogels which render them promising candidates for tissue engineering

  17. Optical Projection Tomography Technique for Image Texture and Mass Transport Studies in Hydrogels Based on Gellan Gum.

    Science.gov (United States)

    Soto, Ana M; Koivisto, Janne T; Parraga, Jenny E; Silva-Correia, Joana; Oliveira, Joaquim M; Reis, Rui L; Kellomäki, Minna; Hyttinen, Jari; Figueiras, Edite

    2016-05-24

    The microstructure and permeability are crucial factors for the development of hydrogels for tissue engineering, since they influence cell nutrition, penetration, and proliferation. The currently available imaging methods able to characterize hydrogels have many limitations. They often require sample drying and other destructive processing, which can change hydrogel structure, or they have limited imaging penetration depth. In this work, we show for the first time an alternative nondestructive method, based on optical projection tomography (OPT) imaging, to characterize hydrated hydrogels without the need of sample processing. As proof of concept, we used gellan gum (GG) hydrogels obtained by several cross-linking methods. Transmission mode OPT was used to analyze image microtextures, and emission mode OPT to study mass transport. Differences in hydrogel structure related to different types of cross-linking and between modified and native GG were found through the acquired Haralick's image texture features followed by multiple discriminant analysis (MDA). In mass transport studies, the mobility of FITC-dextran (MW 20, 150, 2000 kDa) was analyzed through the macroscopic hydrogel. The FITC-dextran velocities were found to be inversely proportional to the size of the dextran as expected. Furthermore, the threshold size in which the transport is affected by the hydrogel mesh was found to be 150 kDa (Stokes' radii between 69 and 95 Å). On the other hand, the mass transport study allowed us to define an index of homogeneity to assess the cross-linking distribution, structure inside the hydrogel, and repeatability of hydrogel production. As a conclusion, we showed that the set of OPT imaging based material characterization methods presented here are useful for screening many characteristics of hydrogel compositions in relatively short time in an inexpensive manner, providing tools for improving the process of designing hydrogels for tissue engineering and drugs

  18. Preparation and characterisation of acrylamide/maleic acid hydrogel

    Directory of Open Access Journals (Sweden)

    Klinpituksa, P.

    2005-09-01

    Full Text Available Acrylamide/maleic acid hydrogel, a superabsorbent polymer, was prepared by free radical polymerization in aqueous solution of acrylamide (AAm and maleic acid (MA : monomer and comonomer, respectively. Potassium persulfate and N,N,N’,N’-tetramethylethylenediamine were used as an initiator system. Also, ethylene glycol dimethacrylate (EGDMA and N,N’-methylenebisacrylamide (MBA were used as crosslinkers. Different compositions of acrylamide, maleic acid and crosslinkers were employed. Water swelling, equilibrium water content and swelling power of the hydrogel formed were determined. The result showed that the swelling in water at equilibrium of hydrogels was in the range of 8,420-10,300% and 3,160- 3,560%, equilibrium water content was in the range of 0.9880-0.9902 and 0.9630-0.9727 and swelling power was in the range of 84-103 and 31-36 using 1%EGDMA and 1%MBA as crosslinkers, respectively. The diffusion of water into hydrogel followed non-Fickian character based on swelling power.

  19. Novel copper (II) alginate hydrogels and their potential for use as anti-bacterial wound dressings

    International Nuclear Information System (INIS)

    The incorporation of a metal ion, with antimicrobial activity, into an alginate dressing is an attractive approach to minimize infection in a wound. In this work, copper (II) cross-linked alginate hydrogels were successfully prepared using a two-step cross-linking procedure. In the first step, solid alginate films were prepared using a solvent-casting method from soft gels of alginate solutions that had been lightly cross-linked using a copper (II) (Cu2+) sulfate solution. In the second step, the films were further cross-linked in a corresponding Cu2+ sulfate solution using a dipping method to further improve their dimensional stability. Alginate solution (at 2%w/v) and Cu2+ sulfate solution (at 2%w/v) in acetate buffer at a low pH provided soft films with excellent swelling behavior. An increase in either Cu2+ ion concentration or cross-linking time led to hydrogels with more densely-cross-linked networks that limited water absorption. The hydrogels clearly showed antibacterial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and Streptococcus pyogenes, which was proportional to the Cu2+ ion concentration. Blood coagulation studies showed that the tested copper (II) cross-linked alginate hydrogels had a tendency to coagulate fibrin, and possibly had an effect on pro-thrombotic coagulation and platelet activation. Conclusively, the prepared films are likely candidates as antibacterial wound dressings. (paper)

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

    Science.gov (United States)

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

    2016-11-01

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

  1. Self-Healing Elastin-Bioglass Hydrogels.

    Science.gov (United States)

    Zeng, Qiongyu; Desai, Malav S; Jin, Hyo-Eon; Lee, Ju Hun; Chang, Jiang; Lee, Seung-Wuk

    2016-08-01

    Tailorable hydrogels that are mechanically robust, injectable, and self-healable, are useful for many biomedical applications including tissue repair and drug delivery. Here we use biological and chemical engineering approaches to develop a novel in situ forming organic/inorganic composite hydrogel with dynamic aldimine cross-links using elastin-like polypeptides (ELP) and bioglass (BG). The resulting ELP/BG biocomposites exhibit tunable gelling behavior and mechanical characteristics in a composition and concentration dependent manner. We also demonstrate self-healing in the ELP/BG hydrogels by successfully reattaching severed pieces as well as through rheology. In addition, we show the strength of genetic engineering to easily customize ELP by fusing cell-stimulating "RGD" peptide motifs. We showed that the resulting composite materials are cytocompatible as they support the cellular growth and attachment. Our robust in situ forming ELP/BG composite hydrogels will be useful as injectable scaffolds for delivering cell and drug molecules to promote soft tissue regeneration in the future. PMID:27380227

  2. 1.3. Features of formation of cross-linked polymers of ethynyl-piperidol

    International Nuclear Information System (INIS)

    This article is devoted to features of formation of cross-linked polymers of ethynyl-piperidol. Therefore, the synthesis of cross-linked polymers was carried out. For the synthesis were used the multifunctional (ethynyl vinyl trimethyl piperidol, isopropenyl trimethyl ethynyl piperidol, N-vinyl pyrrolidone) and bifunctional monomers of N,N'-methyl bis acrylamide and ethylene glycol dimethacrylate. The reaction was carried out in organic solvent and in water. Properties of hydrogels obtained on the base of homopolymers of ethynyl-piperidol derivatives were considered. Properties of hydrogels obtained on the base of copolymers of ethynyl-piperidol derivatives were considered as well.

  3. Controlled release of simvastatin from in situ forming hydrogel triggers bone formation in MC3T3-E1 cells.

    Science.gov (United States)

    Park, Yoon Shin; David, Allan E; Park, Kyung Min; Lin, Chia-Ying; Than, Khoi D; Lee, Kyuri; Park, Jun Beom; Jo, Inho; Park, Ki Dong; Yang, Victor C

    2013-04-01

    Simvastatin (SIM), a drug commonly administered for the treatment of hypercholesterolemia, has been recently reported to induce bone regeneration/formation. In this study, we investigated the properties of hydrogel composed of gelatin-poly(ethylene glycol)-tyramine (GPT) as an efficient SIM delivery vehicle that can trigger osteogenic differentiation. Sustained delivery of SIM was achieved through its encapsulation in an injectable, biodegradable GPT-hydrogel. Cross-linking of the gelatin-based GPT-hydrogel was induced by the reaction of horse radish peroxidase and H(2)O(2). GPT-hydrogels of three different matrix stiffness, 1,800 (GPT-hydrogel1), 5,800 (GPT-hydrogel2), and 8,400 Pa (GPT-hydrogel3) were used. The gelation/degradation time and SIM release profiles of hydrogels loaded with two different concentrations of SIM, 1 and 3 mg/ml, were also evaluated. Maximum swelling times of GPT-hydrogel1, GPT-hydrogel2, and GPT-hydrogel3 were observed to be 6, 12, and 20 days, respectively. All GPT-hydrogels showed complete degradation within 55 days. The in vitro SIM release profiles, investigated in PBS buffer (pH 7.4) at 37°C, exhibited typical biphasic release patterns with the initial burst being more rapid with GPT-hydrogel1 compared with GPT-hydrogel3. Substantial increase in matrix metalloproteinase-13, osteocalcin expression levels, and mineralization were seen in osteogenic differentiation system using MC3T3-E1 cells cultured with GPT-hydrogels loaded with SIM in a dose-dependent manner. This study demonstrated that controlled release of SIM from a biodegradable, injectable GPT-hydrogel had a promising role for long-term treatment of chronic degenerative diseases such as disc degenerative disease. PMID:23250670

  4. Photoactive Self-Shaping Hydrogels as Noncontact 3D Macro/Microscopic Photoprinting Platforms.

    Science.gov (United States)

    Liao, Yue; An, Ning; Wang, Ning; Zhang, Yinyu; Song, Junfei; Zhou, Jinxiong; Liu, Wenguang

    2015-12-01

    A photocleavable terpolymer hydrogel cross-linked with o-nitrobenzyl derivative cross-linker is shown to be capable of self-shaping without losing its physical integrity and robustness due to spontaneous asymmetric swelling of network caused by UV-light-induced gradient cleavage of chemical cross-linkages. The continuum model and finite element method are used to elucidate the curling mechanism underlying. Remarkably, based on the self-changing principle, the photosensitive hydrogels can be developed as photoprinting soft and wet platforms onto which specific 3D characters and images are faithfully duplicated in macro/microscale without contact by UV light irradiation under the cover of customized photomasks. Importantly, a quick response (QR) code is accurately printed on the photoactive hydrogel for the first time. Scanning QR code with a smartphone can quickly connect to a web page. This photoactive hydrogel is promising to be a new printing or recording material. PMID:26439808

  5. Solvent and solute ingress into hydrogels resolved by a combination of imaging techniques

    Science.gov (United States)

    Wagner, D.; Burbach, J.; Grünzweig, C.; Hartmann, S.; Lehmann, E.; Egelhaaf, S. U.; Hermes, H. E.

    2016-05-01

    Using simultaneous neutron, fluorescence, and optical brightfield transmission imaging, the diffusion of solvent, fluorescent dyes, and macromolecules into a crosslinked polyacrylamide hydrogel was investigated. This novel combination of different imaging techniques enables us to distinguish the movements of the solvent and fluorescent molecules. Additionally, the swelling or deswelling of the hydrogels can be monitored. From the sequence of images, dye and solvent concentrations were extracted spatially and temporally resolved. Diffusion equations and different boundary conditions, represented by different models, were used to quantitatively analyze the temporal evolution of these concentration profiles and to determine the diffusion coefficients of solvent and solutes. Solute size and network properties were varied and their effect was investigated. Increasing the crosslinking ratio or partially drying the hydrogel was found to hinder solute diffusion due to the reduced pore size. By contrast, solvent diffusion seemed to be slightly faster if the hydrogel was only partially swollen and hence solvent uptake enhanced.

  6. Molecular design and characterization of biodegradable crosslinked copolyesters

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Y.K.; Han, S.J. [Dongguk University, Seoul (Korea)

    2001-01-01

    Crosslinked poly(glycerol-co-malate)s were synthesized from L-malic acid in Krebs cycle and glycerol. The synthesized polymer was identified by FT-IR spectroscopy. Swelling degrees of the copolymer hydrogels were increased with an increase in pH of the aqueous solution. Hydrolytic behaviors of the crosslinked copolymers were investigated in various pH buffer solutions at 37 deg. C. The hydrolysis of the copolymers proceeded faster with increasing pH of the aqueous solution. Releasing behaviors of the model drug such as diclofenac monosodium salt were also measured in various pH aqueous solutions at 37 deg. C. The release concentration of diclofenac monosodium salt from the hydrogel systems was increased with increasing pH. These facts indicate that the unreacted carboxyl and hydroxyl groups in the copolymers are greatly affected by pH in the conditions. (author). 18 refs., 1 tab., 9 figs.

  7. Mechanical Robust and Self-Healable Supramolecular Hydrogel.

    Science.gov (United States)

    Zheng, Jing; Xiao, Peng; Liu, Wei; Zhang, Jiawei; Huang, Youju; Chen, Tao

    2016-02-01

    Development of self-healing polymers with spontaneous self-healing capability and good mechanical performance is highly desired and remains a great challenge. Here, mechanical robust and self-healable supramolecular hydrogels have been fabricated by using poly(2-dimethylaminoethyl methacrylate) brushes modified silica nanoparticles (SiO2 @PDMAEMA) as multifunctional macrocrosslinkers in a poly(acrylic acid) (PAA) network structure. The SiO2 nanoparticles serve as noncovalent crosslinkers, dissipating energy, whereas the electrostatic interactions between cationic PDMAEMA and anionic PAA render the hydrogel self-healing property. This process provides a simple and broadly applicable strategy to produce mechanical strong and self-healable materials. PMID:26647774

  8. STUDY ON ASPIRIN-MAA HYDROGEL MIP SYSTEM

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaohang; CHENG Guoxiang; LI Guohua

    2008-01-01

    The controUed release system of MIP-Asp hydrogel was prepared by using self-assembly molecular imprinted technique (MIP).1H NMR was used to detect the changes of active hydrogen atoms.Moreover, the effect of crosslinkin8 degree of hydrogel on the release of medicine was investigated and the temperature/pH sensitivity was also considered.The results demonstrated that: the MIPs-Asp was a procedure involving the participation of active hydrogen; the lower crosslinking degree corresponded to the higher medicine release ratio; high temperature is better for the release; weak acidity is better for the release of Asp.

  9. Synthesis of an Intein-mediated Artificial Protein Hydrogel

    OpenAIRE

    Ramirez, Miguel A.; Chen, Zhilei

    2014-01-01

    We present the synthesis of a highly stable protein hydrogel mediated by a split-intein-catalyzed protein trans-splicing reaction. The building blocks of this hydrogel are two protein block-copolymers each containing a subunit of a trimeric protein that serves as a crosslinker and one half of a split intein. A highly hydrophilic random coil is inserted into one of the block-copolymers for water retention. Mixing of the two protein block copolymers triggers an intein trans-splicing reaction, y...

  10. Insitu grafting silica nanoparticles reinforced nanocomposite hydrogels

    Science.gov (United States)

    Yang, Jun; Han, Chun-Rui; Duan, Jiu-Fang; Xu, Feng; Sun, Run-Cang

    2013-10-01

    Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties.Highly flexible nanocomposite hydrogels were prepared by using silica nanoparticles (SNPs) as fillers and multi-functional cross-links to graft hydrophilic poly(acrylic acid) (PAA) by free radical polymerization from an aqueous solution. The SNPs were collected by neighboring polymer chains and dispersed uniformly within a PAA matrix. The mechanical properties of the nanocomposite hydrogels were tailored by the concentration of SNPs according to the percolation model. It was proposed that covalent bonds of adsorbed chains on the filler surface resulted in the formation of a shell of an immobilized glassy layer and trapped entanglements, where the glassy polymer layer greatly enhanced the elastic modulus and the release of trapped entanglements at deformation contributed to the viscoelastic properties. Electronic supplementary information (ESI) available: FTIR spectra of SNP after silane treatment, dynamic oscillatory shear measurements as a function of frequency, constrained polymer chain analysis by a change in the peak height in loss factor spectra, molecular weight of grafted chains at different stages of gelation, prediction of the SNP reinforcing mechanism in the

  11. Swelling characteristics of hydroxyethylmethacrylate/ methacrylic acid pH -sensitive hydrogel as a drug delivery system

    OpenAIRE

    M. Falamarzian- J. Varshosaz

    1996-01-01

    Hydroxyethyl methacrylate /methacrylic acid (HEMA/MAA) copolymer cross-linked with ethylenglycol dimethacrylate was prepared by a bulk.free radical polymerization method. The results indicate that this polymer is a pH -sensitive hydrogel which is collapsed in the acidic medium but completely swollen in the alkaline and neutral pH . it was determined that a proportion of 40% of MAA, the ionizing monomer of this hydrogel, was the best concentration among the different percentages used which sho...

  12. Design of a Drug-Delivery System Based On Polyacrylamide Hydrogels. Evaluation of Structural Properties

    OpenAIRE

    Ferreira, L; Vidal, M. M.; Gil, M. H.

    2001-01-01

    It is well known that hydrogels can be suitable for biomedical, agricultural, and industrial applications. In particular, they have been widely used for the preparation of drug-delivery systems. The preparation and characterization of such a system should be useful for introducing students to these materials. This paper describes the preparation of polyacrylamide hydrogels having different crosslinking densities from the view of optimizing this system for acetylsalicylic acid (aspirin) releas...

  13. Photoinitiator-Free Synthesis of Endothelial Cell Adhesive and Enzymatically Degradable Hydrogels

    OpenAIRE

    Jones, Derek R.; Marchant, Roger E.; von Recum, Horst; Gupta, Anirban Sen; Kottke-Marchant, Kandice

    2014-01-01

    We report on a photoinitiator-free synthetic method of incorporating bioactivity into poly(ethylene glycol) (PEG) hydrogels in order to control physical properties, enzymatic biodegradability and cell-specific adhesiveness of the polymer network, while eliminating the need for UV-mediated photopolymerization. To accomplish this, hydrogel networks were polymerized using Michael addition with four-arm PEG acrylate (10 kDa), using a collagenase sensitive peptide (CSP) as a crosslinker, and intro...

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

    OpenAIRE

    Wei-Min Cheng; Xiang-Ming Hu; De-Ming Wang; Guo-Hua Liu

    2015-01-01

    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 Four...

  15. Mesenchymal stem cell-laden anti-inflammatory hydrogel enhances diabetic wound healing

    OpenAIRE

    Shixuan Chen; Junbin Shi; Min Zhang; Yinghua Chen; Xueer Wang; Lei Zhang; Zhihui Tian; Yuan Yan; Qinglin Li; Wen Zhong; Malcolm Xing; Lu Zhang; Lin Zhang

    2015-01-01

    The purpose of this study was to permit bone marrow mesenchymal stem cells (BMSCs) to reach their full potential in the treatment of chronic wounds. A biocompatible multifunctional crosslinker based temperature sensitive hydrogel was developed to deliver BMSCs, which improve the chronic inflammation microenvironments of wounds. A detailed in vitro investigation found that the hydrogel is suitable for BMSC encapsulation and can promote BMSC secretion of TGF-β1 and bFGF. In vivo, full-thickness...

  16. Preparation of novel biodegradable pHEMA hydrogel for a tissue engineering scaffold by microwave-assisted polymerization

    Institute of Scientific and Technical Information of China (English)

    Li Zhang; Gen-Jian Zheng; Ya-Tong Guo; Lan Zhou; Jie Du; Hong He

    2014-01-01

    Objective:To prepare a novel biodegradable poly(2-hydroxyethylmethacrilate)(pHEMA) hydrogel as tissue engineering scaffold.Methods:The pHEMA hydrogel was synthesized by microwave-assisted polymerization using2-hydroxyethyl methacrylate(HEMA) as the raw material, potassium persulfate as the initiator, andPCLX as the cross-linking additive.The hydrogels was characterized withFTIR andNMR spectroscopy.The physical and chemical properties of the prepared hydrogel were evaluated, and its degradation performance was tested.The cytotoxicity of the optimum composite hydrogel was measured by anMTT assay to confirm the feasibility of its use in tissue engineering.Results:The optimum conditions under which the hydrogel was prepared by microwave-assisted polymerization are as follows:1.5 g cross-linking additive,0.3 g initiator, reaction temperature of80℃, and microwave power of800W.Degradation studies showed good degradation profiles with75% in17 days.Additionally, the hydrogels did not elicit any cytotoxic response inin vitro cytotoxic assays.Conclusion:A biodegradable pHEMA hydrogel was successfully prepared by microwave-assisted polymerization, as confirmed from FTIR andNMR results.The hydrogel shows promising applications in tissue engineering, and its healing ability and biocompatibility will be evaluated in detail in the future.

  17. Nanostructuring biosynthetic hydrogels for tissue engineering: a cellular and structural analysis.

    Science.gov (United States)

    Frisman, Ilya; Seliktar, Dror; Bianco-Peled, Havazelet

    2012-01-01

    The nanostructuring of hydrogel scaffolds used in tissue engineering provides the ability to control cellular fate and tissue morphogenesis through cell-matrix interactions. Here we describe a method to provide nanostructure to a biosynthetic hydrogel scaffold made from crosslinked poly(ethylene glycol)-fibrinogen conjugates (PEG-fibrinogen), by modifying them with the block-copolymer Pluronic® F127. The copolymeric additive self-assembled into micelles at certain concentrations and temperatures, thereby creating nanostructures within the crosslinked hydrogel. Small-angle X-ray scattering (SAXS) and transmission electron microscopy at cryogenic temperature were used to detect Pluronic® F127 micelles embedded within the crosslinked PEG-fibrinogen hydrogels. The density and order of the micelles within the hydrogel matrix increased as the relative Pluronic® F127 concentration was raised. The transient stability of the micelles within the hydrogel network was analyzed using time-dependent swelling and Pluronic® F127 release measurements. These characterizations revealed that most of the Pluronic® F127 molecules diffuse out of the hydrogels after 4 days in aqueous buffer and SAXS analysis confirmed a significant change in the structure and interactions of the micelles during this time. Cell culture experiments evaluating the three-dimensional fibroblast morphology within the matrix indicated a strong correlation between cell spreading and the hydrogel's characteristic mesh size. The present research thereby provides a more quantitative understanding of how structural features in an encapsulating hydrogel environment can affect cell morphogenesis towards tissue regeneration. PMID:21855662

  18. Tissue-Integratable and Biocompatible Photogelation by the Imine Crosslinking Reaction.

    Science.gov (United States)

    Yang, Yunlong; Zhang, Jieyuan; Liu, Zhenzhen; Lin, Qiuning; Liu, Xiaolin; Bao, Chunyan; Wang, Yang; Zhu, Linyong

    2016-04-01

    A novel photogelling mechanism by the phototriggered-imine-crosslinking (PIC) reaction is demonstrated. Hyaluronic acid grafted with o-nitrobenzene, a photogenerated aldehyde group, can quickly photo-crosslink with amino-bearing polymers or proteins. Once the in situ photogelling on a wound occurs, the PIC gelling process can well integrate a hydrogel with surrounding tissue by covalent bonding, thus making it a powerful tool for tissue engineering and regenerative medicine. PMID:26840751

  19. 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.

  20. A Synthetic Thermosensitive Hydrogel for Cartilage Bioprinting and Its Biofunctionalization with Polysaccharides.

    Science.gov (United States)

    Abbadessa, Anna; Mouser, Vivian H M; Blokzijl, Maarten M; Gawlitta, Debby; Dhert, Wouter J A; Hennink, Wim E; Malda, Jos; Vermonden, Tina

    2016-06-13

    Hydrogels based on triblock copolymers of polyethylene glycol and partially methacrylated poly[N-(2-hydroxypropyl) methacrylamide mono/dilactate] make up an attractive class of biomaterials because of their biodegradability, cytocompatibility, and tunable thermoresponsive and mechanical properties. If these properties are fine-tuned, the hydrogels can be three-dimensionally bioprinted, to generate, for instance, constructs for cartilage repair. This study investigated whether hydrogels based on the polymer mentioned above with a 10% degree of methacrylation (M10P10) support cartilage formation by chondrocytes and whether the incorporation of methacrylated chondroitin sulfate (CSMA) or methacrylated hyaluronic acid (HAMA) can improve the mechanical properties, long-term stability, and printability. Chondrocyte-laden M10P10 hydrogels were cultured for 42 days to evaluate chondrogenesis. M10P10 hydrogels with or without polysaccharides were evaluated for their mechanical properties (before and after UV photo-cross-linking), degradation kinetics, and printability. Extensive cartilage matrix production occurred in M10P10 hydrogels, highlighting their potential for cartilage repair strategies. The incorporation of polysaccharides increased the storage modulus of polymer mixtures and decreased the degradation kinetics in cross-linked hydrogels. Addition of HAMA to M10P10 hydrogels improved printability and resulted in three-dimensional constructs with excellent cell viability. Hence, this novel combination of M10P10 with HAMA forms an interesting class of hydrogels for cartilage bioprinting. PMID:27171342

  1. Tough and Cell-Compatible Chitosan Physical Hydrogels for Mouse Bone Mesenchymal Stem Cells in Vitro.

    Science.gov (United States)

    Ding, Beibei; Gao, Huichang; Song, Jianhui; Li, Yaya; Zhang, Lina; Cao, Xiaodong; Xu, Min; Cai, Jie

    2016-08-01

    Most hydrogels involve synthetic polymers and organic cross-linkers that cannot simultaneously fulfill the mechanical and cell-compatibility requirements of biomedical applications. We prepared a new type of chitosan physical hydrogel with various degrees of deacetylation (DDs) via the heterogeneous deacetylation of nanoporous chitin hydrogels under mild conditions. The DD of the chitosan physical hydrogels ranged from 56 to 99%, and the hydrogels were transparent and mechanically strong because of the extra intra- and intermolecular hydrogen bonding interactions between the amino and hydroxyl groups on the nearby chitosan nanofibrils. The tensile strength and Young's modulus of the chitosan physical hydrogels were 3.6 and 7.9 MPa, respectively, for a DD of 56% and increased to 12.1 and 92.0 MPa for a DD of 99% in a swelling equilibrium state. In vitro studies demonstrated that mouse bone mesenchymal stem cells (mBMSCs) cultured on chitosan physical hydrogels had better adhesion and proliferation than those cultured on chitin hydrogels. In particular, the chitosan physical hydrogels promoted the differentiation of the mBMSCs into epidermal cells in vitro. These materials are promising candidates for applications such as stem cell research, cell therapy, and tissue engineering. PMID:27410199

  2. IPN hydrogel nanocomposites based on agarose and ZnO with antifouling and bactericidal properties.

    Science.gov (United States)

    Wang, Jingjing; Hu, Hongkai; Yang, Zhonglin; Wei, Jun; Li, Juan

    2016-04-01

    Nanocomposite hydrogels with interpenetrating polymer network (IPN) structure based on poly(ethylene glycol) methyl ether methacrylate modified ZnO (ZnO-PEGMA) and 4-azidobenzoic agarose (AG-N3) were prepared by a one-pot strategy under UV irradiation. The hydrogels exhibited a highly macroporous spongelike structure, and the pore size decreased with the increase of the ZnO-PEGMA content. Due to the entanglement and favorable interactions between the two crosslinked networks, the IPN hydrogels exhibited excellent mechanical strength and light transmittance. The maximum compressive and tensile strengths of the IPN hydrogels reached 24.8 and 1.98MPa respectively. The transparent IPN hydrogels transmitted more than 85% of visible light at all wavelengths (400-800nm). The IPN hydrogels exhibited anti-adhesive property towards Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), and the bactericidal activity increased with the ZnO-PEGMA content. The incorporation of ZnO-PEGMA did not reduce the biocompatibility of the IPN hydrogels and all the IPN nanocomposites showed negligible cytotoxicity. The present study not only provided a facile method for preparing hydrogel nanocomposites with IPN structure but also developed a new hydrogel material which might be an excellent candidate for wound dressings. PMID:26838864

  3. A new route to fabricate biocompatible hydrogels with controlled drug delivery behavior.

    Science.gov (United States)

    Hu, Xiaohong; Gong, Xiao

    2016-05-15

    Hydrogels for drug delivery have attracted extensive interests since they can be used for biomaterials such as contact lenses. Here, we report that biocompatible hydrogels for contact lenses with controlled drug delivery behavior can be fabricated using copolymer hydrogels and Layer-by-Layer (LbL) surface modification technique. Methyl acrylic anhydride (MAA) modified β-cyclodextrin (β-CD) (MA-β-CD) was synthesized and copolymerized with hydroxyethyl methacrylate (HEMA) to form copolymer hydrogel. The introduction of second monomer of MA-β-CD would accelerate the polymerization of hydrogel, leading to increase of residual CC groups. The structure of copolymers was characterized by differential scanning calorimetry (DSC). Transparence, equilibrium swelling ratio and contact angle of copolymer hydrogel were also detailed discussed in the work. In vitro drug release results showed that copolymer hydrogel with higher MA-β-CD content exhibited a better drug loading capacity and drug release behaviors could be tuned by MA-β-CD/monomer ratio. Finally, alkynyl functional hyaluronic acid (HA-BP) and nitrine functional chitosan (CS-N3) were synthesized and covalently cross-linked to copolymer hydrogel surface using LbL technique through click chemistry. The successful LbL multilayers were confirmed by X-ray Photoelectron Spectroscopy (XPS). Resultsofcytotoxicityexperiment revealed that the hydrogels were biocompatible since they could support the growth of cells. PMID:26930541

  4. Simple approach to reinforce hydrogels with cellulose nanocrystals

    Science.gov (United States)

    Yang, Jun; Han, Chun-Rui; Xu, Feng; Sun, Run-Cang

    2014-05-01

    The physical crosslinking of colloidal nanoparticles via dynamic and directional non-covalent interactions has led to significant advances in composite hydrogels. In this paper, we report a simple approach to fabricate tough, stretchable and hysteretic isotropic nanocomposite hydrogels, where rod-like cellulose nanocrystals (CNCs) are encapsulated by flexible polymer chains of poly(N,N-dimethylacrylamide) (PDMA). The CNC-PDMA colloidal clusters build a homogeneously cross-linked network and lead to significant reinforcing effect of the composites. Hierarchically structured CNC-PDMA clusters, from isolated particles to an interpenetrated network, are observed by transmission electron microscopy measurements. Dynamic shear oscillation measurements are applied to demystify the differences in network rheological behaviors, which were compared with network behaviors of chemically cross-linked PDMA counterparts. Tensile tests indicate that the hybrid hydrogels possess higher mechanical properties and a more efficient energy dissipation mechanism. In particular, with only 0.8 wt% of CNC loading, a 4.8-fold increase in Young's modulus, 9.2-fold increase in tensile strength, and 5.8-fold increase in fracture strain are achieved, which is ascribed to a combination of CNC reinforcement in the soft matrix and CNC-PDMA colloidal cluster conformational rearrangement under stretching. Physical interactions within networks serve as reversible sacrificial bonds that dissociate upon deformation, exhibiting large hysteresis as an energy dissipation mechanism via cluster mobility. This result contrasts with the case of chemically cross-linked PDMA counterparts where the stress relaxation is slow due to the permanent cross-links and low resistance against crack propagation within the covalent network.The physical crosslinking of colloidal nanoparticles via dynamic and directional non-covalent interactions has led to significant advances in composite hydrogels. In this paper, we report

  5. Interpenetrating Polymer Network Hydrogels Based on Gelatin and PVA by Biocompatible Approaches: Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    Eltjani-Eltahir Hago

    2013-01-01

    Full Text Available In this work, a new approach was introduced to prepare interpenetrating polymer network PVA/GE hydrogels by cross-linking of various concentration gelatin in the presence of transglutaminase enzyme by using the freezing-thawing cycles technique. The effects of freezing-thawing cycles on the properties of morphological characterization, gel fraction, swelling, mechanical, and MTT assay were investigated. The IPN PVA/GE hydrogels showed excellent physical and mechanical Properties. MTT assay data and the fibroblasts culture also showed excellent biocompatibility and good proliferation. This indicates that the IPN hydrogels are stable enough for various biomedical applications.

  6. Synthesis and characterization of thermosensitive hydrogels and the investigation of modified release of ibuprofen

    Directory of Open Access Journals (Sweden)

    Ilić-Stojanović Snežana S.

    2013-01-01

    Full Text Available The method of the synthesis of poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate hydrogels obtained by radical polymerization is described. Their characterization was carried out by the determination of the quantity of residual monomers and by investigating their structure using the FTIR. Three glass transitions were detected by DSC method. The porous surfaces of hydrogels with incorporated ibuprofen were shown in SEM micrographs. The swelling ratio of hydrogels decreased with the temperature increase and the swelling transport mechanism was changed from non-Fickian to Fickian. Ibuprofen was incorporated in hydrogel as a drug carrier and released quantity was monitored by HPLC method depending on the temperature. Hydrogel with the lower cross-linker content had the highest swelling degree (α = 34.72 at 10°C and released the largest amount of ibuprofen (64.21 mg/gxerogel at 40°C. [Projekat Ministarstva nauke Republike Srbije, br. TR-34012

  7. A modified emulsion gelation technique to improve buoyancy of hydrogel tablets for floating drug delivery systems.

    Science.gov (United States)

    Yom-Tov, Ortal; Seliktar, Dror; Bianco-Peled, Havazelet

    2015-10-01

    The use of buoyant or floating hydrogel tablets is of particular interest in the sustained release of drugs to the stomach. They have an ability to slow the release rates of drugs by prolonging their absorption window in the upper part of the gastrointestinal (GI) tract. In this study we synthesized bioactive hydrogels that have sustainable release rates for drugs in the stomach based on a hydrogel preparation technique that employs emulsifying surfactants. The emulsion gelation technique, which encapsulates oil droplets within the hydrogels during crosslinking, was used to decrease their specific gravity in aqueous environments, resulting in floating drug release depots. Properties such as swelling, buoyancy, density and drug release were manipulated by changing the polymer concentrations, surfactant percentages and the oil:polymer ratios. The relationship between these properties and the hydrogel's floating lag time was documented. The potential for this material to be used as a floating drug delivery system was demonstrated. PMID:26117764

  8. Small-angle neutron scattering from polymer hydrogels with memory effect for medicine immobilization

    International Nuclear Information System (INIS)

    Hydrogels synthesized based on cross-linked copolymers of 2-hydroxyethyl methacrylate and functional monomers (acrylic acid or dimethylaminoethyl methacrylate), having a memory effect with respect to target medicine (cefazolin), have been investigated by small-angle neutron scattering. The hydrogels are found to have a two-level structural organization: large (up to 100 nm) aggregates filled with network cells (4–7 nm in size). The structural differences in the anionic, cationic, and amphiphilic hydrogels and the relationship between their structure and the ability of hydrogels to absorb moisture are shown. A relationship between the memory effect during cefazolin immobilization and the internal structure of hydrogels, depending on their composition and type of functional groups, is established.

  9. PVA/atapulgite hydrogels

    International Nuclear Information System (INIS)

    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)

  10. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    International Nuclear Information System (INIS)

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation

  11. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    Energy Technology Data Exchange (ETDEWEB)

    Song, YoungShin; Lee, Chang-Soo [Chungnam National University, Daejeon (Korea, Republic of)

    2014-10-15

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation.

  12. Synthesis and properties of collagen-g-poly(sodium acrylate-co-2-hydroxyethylacrylate superabsorbent hydrogels

    Directory of Open Access Journals (Sweden)

    M. Sadeghi

    2013-06-01

    Full Text Available Novel biopolymer-based superabsorbent hydrogels were prepared by grafting crosslinked poly(acrylic acid-co-2-hydroxyethyl acrylate (PAA-co-PHEA chains onto collagen backbones through a free radical polymerization method. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS as initiator and N,N '-methylene bisacrylamide (MBA as crosslinker. A proposed mechanism for collagen-g-(PAA-co-PHEA formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy and TGA thermal analysis. Moreover, the morphology of the samples was examined by scanning electron microscopy (SEM. The effect of concentration of MBA as well as AA/HEA weight ratio on the swelling capacity of the hydrogel was also studied. Furthermore, the water absorbency of hydrogels was measured in solutions with pH ranging 1 to 13. The collagen-based hydrogel exhibited a pH-responsive character, so that a swelling-deswelling pulsatile behavior was recorded at pHs 2 and 8. Preliminary swelling and deswelling behaviors of the hydrogels were also studied. Additionally, the hydrogels exhibited salt-sensitivity and cation exchange properties.

  13. Xylan-based temperature/pH sensitive hydrogels for drug controlled release.

    Science.gov (United States)

    Gao, Cundian; Ren, Junli; Zhao, Cui; Kong, Weiqing; Dai, Qingqing; Chen, Qifeng; Liu, Chuanfu; Sun, Runcang

    2016-10-20

    Xylan-based temperature/pH sensitive hydrogels were prepared by the crosslinking copolymerization of xylan with N-isopropylacrylamide (NIPAm) and acrylic acid (AA) using N,Ń-methylenebis-acrylamide (MBA) as a cross-linker and 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator via ultraviolet irradiation. The influence of the NIPAm, AA and MBA amount on properties of xylan-based hydrogels was discussed. The morphology and interactions of hydrogels were characterized by SEM and FTIR. The lower critical solution temperature (LCST) of hydrogels was investigated by DSC. The results indicated that the LCST of hydrogels emerged at around 34°C and increased with increasing the AA content. The drug encapsulation efficiency of as-prepared hydrogels reached to 97.60% and the cumulative release rate of acetylsalicylic acid was 90.12% and 26.35% in the intestinal and gastric fluid, respectively. Xylan-based hydrogels were proved to be biocompatible with NIH3T3 cell by MTT assay and showed the promising application as drug carriers for the intestinal-targeted oral drug delivery. PMID:27474557

  14. Formulation and characterization of poloxamine-based hydrogels as tissue sealants.

    Science.gov (United States)

    Cho, Eunhee; Lee, Jeoung Soo; Webb, Ken

    2012-07-01

    In situ cross linkable polyethylene glycol (PEG)-based polymers play an increasing role in surgical practice as sealants that provide a barrier to fluid/gas leakage and adhesion formation. This study investigated the gelation behavior and physical properties of hydrogels formed from homogeneous and blended solutions of two acrylated poloxamines (Tetronics® T1107 and T904) of various molecular weights and hydrophilic/lipophilic balances relative to a PEG control. Hydrogels were formed by reverse thermal gelation at physiological temperature (T1107-containing formulations) and covalent crosslinking by Michael-type addition with dithiothreitol. All poloxamine-based hydrogels exhibited thermosensitive behavior and achieved significantly reduced swelling, increased tensile properties and increased tissue bond strength relative to the PEG hydrogel at physiological temperature. Swelling and tensile properties of all poloxamine-based hydrogels were significantly greater at 37°C relative to 4°C, suggesting that their improved physical properties derive from cooperative crosslinking by both noncovalent and covalent mechanisms. Poloxamine-based hydrogels were cytocompatible and underwent hydrolytic degradation over 2-5weeks, depending on their T1107/T904 composition. In conclusion, select poloxamine-based hydrogels possess a number of properties potentially beneficial to tissue sealant applications, including a substantial increase in viscosity between room/physiological temperatures, resistance to cell adhesion and maintenance of a stable volume during equilibration. PMID:22406506

  15. Use of radiation in the production of hydrogels

    International Nuclear Information System (INIS)

    The first hydrogel for wound dressing processed by radiation left the laboratories in Poland in 1986 by the hands of its inventor Janusz M. Rosiak and soon, after formal tests, arrived in the local market (1992). It was a technological breakthrough due to its product characteristics as pain reliever and enhanced healing properties besides its clever production process combining sterilization and crosslinking in a simultaneous operation. IAEA invited professor Rosiak to support the transference of his technology for many laboratories around the world. The laboratories of developing countries, which face all kinds of restrictions, were seduced by the simplicity of the process and low cost of its raw materials. This was the seed of the flourishing activities in hydrogel dressings in Brazil and other developing countries. The technology transfer of the radiation production of hydrogel dressings and other hydrogels to the Brazilian industry is under way. The usual issues associated with radiation processing arise from this experience, i.e. capital costs, misinformation about radiation and lack of expertise on radiation processing. Some other issues concerning local market and social peculiarities also add to the problem. Notwithstanding, many different opportunities arise from those challenges. These technical and commercial issues are roughly: (i) There are plenty of new hydrogels in the market and all say the same. What else radiation processed hydrogels can say? (ii) Regarding to hydrogels and its industrial production as market product, what are the unique characteristics of radiation processing? It was shown that the radiation is a powerful tool for producing hydrogels the same basic formula with improved flexibility, control and purity

  16. Functional stimuli responsive hydrogel devices by self-folding

    International Nuclear Information System (INIS)

    We describe a photolithographic approach to create functional stimuli responsive, self-folding, microscale hydrogel devices using thin, gradient cross-linked hinges and thick, fully cross-linked panels. The hydrogels are composed of poly (N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) with reversible stimuli responsive properties just below physiological temperatures. We show that a variety of three-dimensional structures can be formed and reversibly actuated by temperature or pH. We experimentally characterized the swelling and mechanical properties of pNIPAM-AAc and developed a finite element model to rationalize self-folding and its variation with hinge thickness and swelling ratio. Finally, we highlight applications of this approach in the creation of functional devices such as self-folding polymeric micro-capsules, untethered micro-grippers and thermally steered micro-mirror systems. (paper)

  17. 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. PMID:27178954

  18. A Coarse-Grained Model for Simulating Chitosan Hydrogels

    Science.gov (United States)

    Xu, Hongcheng; Matysiak, Silvina

    Hydrogels are biologically-derived materials composed of water-filled cross-linking polymer chains. It has widely been used as biodegradable material and has many applications in medical devices. The chitosan hydrogel is stimuli-responsive for undergoing pH-sensitive self-assembly process, allowing programmable tuning of the chitosan deposition through electric pulse. To explore the self-assembly mechanism of chitosan hydroge, we have developed an explicit-solvent coarse-grained chitosan model that has roots in the MARTINI force field, and the pH change is modeled by protonating chitosan chains using the Henderson-Hasselbalch equation. The mechanism of hydrogel network formation will be presented. The self-assembled polymer network qualitatively reproduce many experimental observables such as the pH-dependent strain-stress curve, bulk moduli, and structure factor. Our model is also capable of simulating other similar polyelectrolyte polymer systems.

  19. Stimuli-sensitive hydrogels for pharmaceutical and medical applications

    Directory of Open Access Journals (Sweden)

    Ilić-Stojanović Snežana

    2011-01-01

    Full Text Available Hydrogels are three-dimensional cross-linked hydrophilic polymers that swell in water and aqueous solutions without dissolving in them. They are very sensitive to environmental stimulus, which is manifested by a sharp phase transition. This feature is important for their application in the pharmaceutical field, especially for making formulations with controlled release of active ingredients, with the correction of the solubility, degradation and their toxicity reducing. Because of the compatibility with living tissues, hydrogels can be used in different medical purposes (for making contact lenses, stents, balloon catheters, artificial muscles, substitutes for arteries and veins, trachea, oviduct. This work presents methods (chemical and physical for obtaining hydrogels, their properties and sensitivity to environmental stimuli (temperature, pH, magnetic field, as well as their potential application in medicine and pharmacy.

  20. Gelatin-Methacryloyl Hydrogels: Towards Biofabrication-Based Tissue Repair.

    Science.gov (United States)

    Klotz, Barbara J; Gawlitta, Debby; Rosenberg, Antoine J W P; Malda, Jos; Melchels, Ferry P W

    2016-05-01

    Research over the past decade on the cell-biomaterial interface has shifted to the third dimension. Besides mimicking the native extracellular environment by 3D cell culture, hydrogels offer the possibility to generate well-defined 3D biofabricated tissue analogs. In this context, gelatin-methacryloyl (gelMA) hydrogels have recently gained increased attention. This interest is sparked by the combination of the inherent bioactivity of gelatin and the physicochemical tailorability of photo-crosslinkable hydrogels. GelMA is a versatile matrix that can be used to engineer tissue analogs ranging from vasculature to cartilage and bone. Convergence of biological and biofabrication approaches is necessary to progress from merely proving cell functionality or construct shape fidelity towards regenerating tissues. GelMA has a critical pioneering role in this process and could be used to accelerate the development of clinically relevant applications. PMID:26867787

  1. Temperature-sensitivity and cell biocompatibility of freeze-dried nanocomposite hydrogels incorporated with biodegradable PHBV

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qingsong, E-mail: zqs8011@163.com; Chen, Li, E-mail: chenlis@tjpu.edu.cn; Dong, Youyu; Lu, Si

    2013-04-01

    The structure, morphology, thermal behaviors and cytotoxicity of novel hydrogels, composed of poly(N-isopropylacrylamide)(PNIPAM) and biodegradable polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) under nanoclay hectorite “Laponite XLG” severed as physical cross-linker, were characterized by X-ray diffraction, scanning electron microscopy, gravimetric method, differential scanning calorimetry, and cell culture experiments. It was found that, due to the introduction of hydrophobic PHBV, the homogeneity of interior pore in the pure PNIPAM nanocomposite hydrogel was disrupted, the transparency and swelling degree gradually decreased. Although the weight ratio between PHBV and NIPAM increased from 5 to 40 wt.%, the volume phase transition temperature (VPTTs) of hydrogel were not altered compared with the pure PNIPAM nanocomposite hydrogel. No matter what PHBV content, the PHBV/PNIPAM/Hectorite hydrogels always exhibit good stimuli-responsibility. In addition, human hepatoma cells(HepG2) adhesion and spreading on the surface of PHBV-based hydrogels was greatly improved than that of pure PNIPAM nanocomposite hydrogel at 37 °C due to the introduction of PHBV. Highlights: ► Thermo-responsive and cell biocompatible hydrogels incorporated PHBV was synthesized. ► The introduction of PHBV decreases the transparency of nanocomposite hydrogel. ► The introduction of PHBV has a little shift on VPTTs of nanocomposite hydrogel. ► The HepG2 cells could adhere and spread on the surface of PHBV-based hydrogels. ► Cell sheet could be detached simultaneously from the surface of hydrogels.

  2. In situ synthesis of magnetic CaraPVA IPN nanocomposite hydrogels and controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Mahdavinia, Gholam Reza, E-mail: grmnia@maragheh.ac.ir; Etemadi, Hossein

    2014-12-01

    In this work, the magnetic nanocomposite hydrogels that focused on targeted drug delivery were synthesized by incorporation of polyvinyl alcohol (PVA), kappa-carrageenan (Cara), and magnetite Fe{sub 3}O{sub 4} nanoparticles. The magnetic nanoparticles were obtained in situ in the presence of a mixture of polyvinyl alcohol/kappa-carrageenan (CaraPVA). The produced magnetite-polymers were cross-linked with freezing–thawing technique and subsequent with K{sup +} solution. The synthesized hydrogels were thoroughly characterized by transmittance electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. The dynamic swelling kinetic models of hydrogels were analyzed according to the first- and second-order kinetic models and were found that the experimental kinetics data followed the second-order model well. Drug loading and release efficiency were evaluated by diclofenac sodium (DS) as the model drug. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological simulated pHs and external magnetic fields. Investigation on the antibacterial activity revealed the ability of drug-loaded hydrogels to inactivate the Gram-positive Staphylococcus aureus (S. aureus) bacteria. The mucoadhesive properties of the hydrogels were studied and the hydrogels containing kappa-carrageenan showed good mucoadhesiveness in both simulated gastric and intestinal conditions. - Highlights: • In situ synthesis of magnetic kappa-carrageenan/PVA nanocomposite hydrogel. • Low salt sensitivity of magnetic nanocomposite hydrogels was observed. • The release of diclofenac sodium from hydrogels was pH-dependent. • The release of diclofenac sodium from magnetic hydrogels was affected by external magnetic field. • The hydrogels containing carrageenan component showed high

  3. Experiments with hydrogel pearls

    OpenAIRE

    Pavlin, Jerneja

    2015-01-01

    Hydrogels are very attractive materials since they can absorb large quantities of water. They also have very interesting optical properties which can be easily shown. The experiments with hydrogel pearls related to the absorption of water, density, optical properties and influence of pH are presented in the contribution.

  4. A Novel Aerosol Method for the Production of Hydrogel Particles

    Directory of Open Access Journals (Sweden)

    Diana Guzman-Villanueva

    2011-01-01

    Full Text Available A novel method of generating hydrogel particles for various applications including drug delivery purposes was developed. This method is based on the production of hydrogel particles from sprayed polymeric nano/microdroplets obtained by a nebulization process that is immediately followed by gelation in a crosslinking fluid. In this study, particle synthesis parameters such as type of nebulizer, type of crosslinker, air pressure, and polymer concentration were investigated for their impact on the mean particle size, swelling behavior, and morphology of the developed particles. Spherical alginate-based hydrogel particles with a mean particle size in the range from 842 to 886 nm were obtained. Using statistical analysis of the factorial design of experiment it was found that the main factors influencing the size and swelling values of the particles are the alginate concentration and the air pressure. Thus, it was demonstrated that the method described in the current study is promising for the generation of hydrogel particles and it constitutes a relatively simple and low-cost system.

  5. Radio-synthesized polyacrylamide hydrogels for proteins release

    Science.gov (United States)

    Ferraz, Caroline C.; Varca, Gustavo H. C.; Lopes, Patricia S.; Mathor, Monica B.; Lugão, Ademar B.

    2014-01-01

    The use of hydrogels for biomedical purposes has been extensively investigated. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release, using papain and bovine serum albumin as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using γ-radiation under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density and evaluated according to protein release, bioactivity and cytotoxicity. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4-5% (w/v) polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties and proteins. This selection was based on the release of the proteins during the experiment period (up to 50 h), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay it was also adequate for biomedical purposes, however this method was not able to generate a matrix with controlled pore sizes.

  6. Feasibility of hydrogel fiducial markers for in vivo proton range verification using PET

    Science.gov (United States)

    Cho, Jongmin; Campbell, Patrick; Wang, Min; Alqathami, Mamdooh; Mawlawi, Osama; Kerr, Matthew; Cho, Sang Hyun

    2016-03-01

    Biocompatible/biodegradable hydrogel polymers were immersed in 18O-enriched water and 16O-water to create 18O-water hydrogels and 16O-water hydrogels. In both cases, the hydrogels were made of ~91 wt% water and ~9 wt% polymer. In addition, 5-8 μm Zn powder was suspended in 16O-water and 18O-enriched water and cross-linked with hydrogel polymers to create Zn/16O-water hydrogels (30/70 wt%, ~9 wt% polymer) and Zn/18O-water hydrogels (10/90 wt%), respectively. A block of extra-firm ‘wet’ tofu (12.3  ×  8.8  ×  4.9 cm, ρ  ≈  1.05 g cm-3) immersed in water was injected with Zn/16O-water hydrogels (0.9 ml each) at four different depths using an 18-gauge needle. Similarly, Zn/18O-water hydrogels (0.9 ml) were injected into a second tofu phantom. As a reference, both 16O-water hydrogels (1.8 ml) and 18O-water hydrogels (0.9 ml) in Petri dishes were irradiated in a ‘dry’ environment. The hydrogels in the wet tofu phantoms and dry Petri dishes were scanned via CT and images were used for treatment planning. Then, they were positioned at the proton distal dose fall-off region and irradiated (2 Gy) followed by PET/CT imaging. Notably high PET signals were observed only in 18O-water hydrogels in the dry environment. The visibility of the Zn/16O-water hydrogels injected into the tofu phantom was outstanding in CT images, but these hydrogels provided no noticeable PET signals. The visibility of the Zn/18O-water hydrogels in the wet tofu were excellent on CT and moderate on PET; however, the PET signals were weaker than those in the dry environment, possibly owing to 18O-water leaching out. The hydrogel markers studied here could be used to develop universal PET/CT fiducial markers. Their PET visibility (attributed more to activated 18O-water than Zn) after proton irradiation can be used for proton therapy/range verification. More investigation is needed to slow down the leaching of 18O-water.

  7. Enhanced loading efficiency and sustained release of doxorubicin from hyaluronic acid/graphene oxide composite hydrogels by a mussel-inspired catecholamine.

    Science.gov (United States)

    Byun, Eunkyoung; Lee, Haeshin

    2014-10-01

    Hydrogels have been widely investigated as depots and carriers for drug delivery. For example, hydrogels have been successfully used to encapsulate a variety of pharmaceuticals, such as peptides and proteins. Recently, carbon material/hydrogel hybrid systems have been of interest as new hydrogel systems because of the attractiveness of structural reinforcement for biomedical applications. In particular, graphene and graphene oxide (GO) have been recognized as novel biomaterials with unique physical, electrical, and thermal properties. Among the various applications of these materials, many research groups are intensively exploring the biomedical applications of graphene and GO. In this study, we propose a new role for GO in hybrid hydrogels, with the inclusion of GO in the gel network resulting in a nearly 90% enhancement in the loading of small, hydrophobic drugs (e.g., doxorubicin, Dox) compared to the hydrogel without encapsulated GO. The hydrogels were prepared from hyaluronic acid (HA), with a mussel-inspired crosslinking chemistry used to prepare the HA hydrogels. Dox was then loaded into the hydrogels. The HA/GO composite hydrogel not only enhanced the loading amount but also exhibited long-lasting anticancer activity over 10 days. We believe that these graphene oxide-containing composite hydrogels can solve one of the challenges in the application of hydrogels by improving the loading efficiency of small-molecule drugs. PMID:25942800

  8. Bioprinting Cellularized Constructs Using a Tissue-specific Hydrogel Bioink.

    Science.gov (United States)

    Skardal, Aleksander; Devarasetty, Mahesh; Kang, Hyun-Wook; Seol, Young-Joon; Forsythe, Steven D; Bishop, Colin; Shupe, Thomas; Soker, Shay; Atala, Anthony

    2016-01-01

    Bioprinting has emerged as a versatile biofabrication approach for creating tissue engineered organ constructs. These constructs have potential use as organ replacements for implantation in patients, and also, when created on a smaller size scale as model "organoids" that can be used in in vitro systems for drug and toxicology screening. Despite development of a wide variety of bioprinting devices, application of bioprinting technology can be limited by the availability of materials that both expedite bioprinting procedures and support cell viability and function by providing tissue-specific cues. Here we describe a versatile hyaluronic acid (HA) and gelatin-based hydrogel system comprised of a multi-crosslinker, 2-stage crosslinking protocol, which can provide tissue specific biochemical signals and mimic the mechanical properties of in vivo tissues. Biochemical factors are provided by incorporating tissue-derived extracellular matrix materials, which include potent growth factors. Tissue mechanical properties are controlled combinations of PEG-based crosslinkers with varying molecular weights, geometries (linear or multi-arm), and functional groups to yield extrudable bioinks and final construct shear stiffness values over a wide range (100 Pa to 20 kPa). Using these parameters, hydrogel bioinks were used to bioprint primary liver spheroids in a liver-specific bioink to create in vitro liver constructs with high cell viability and measurable functional albumin and urea output. This methodology provides a general framework that can be adapted for future customization of hydrogels for biofabrication of a wide range of tissue construct types. PMID:27166839

  9. Fiber-reinforced tough hydrogels

    OpenAIRE

    Illeperuma, Widusha Ruwangi Kaushalya; Sun, Jeong-Yun; Suo, Zhigang; Vlassak, Joost J.

    2014-01-01

    Using strong fibers to reinforce a hydrogel is highly desirable but difficult. Such a composite would combine the attributes of a solid that provides strength and a liquid that transports matter. Most hydrogels, however, are brittle, allowing the fibers to cut through the hydrogel when the composite is loaded. Here we circumvent this problem by using a recently developed tough hydrogel. We fabricate a composite using an alginate-polyacrylamide hydrogel reinforced with a random network of stai...

  10. Preparation and characterization of gelatin-poly(methacrylic acid) interpenetrating polymeric network hydrogels as a ph-sensitive delivery system for glipizide

    OpenAIRE

    Gupta N; Satish C; Shivakumar H

    2007-01-01

    In the present study, interpenetrating polymeric network hydrogels of glipizide were prepared using gelatin and methacrylic acid. Methacrylic acid was polymerized using potassium persulfate. Methacrylic acid was crosslinked with methylene bisacrylamide and gelatin was crosslinked using glutaraldehyde. Four formulations were prepared by varying the concentrations of methacrylic acid, methylene bisacrylamide and glutaraldehyde. The amounts of gelatin and potassium persulfate were kept constant ...

  11. Nonfouling hydrogels formed from charged monomer subunits.

    Science.gov (United States)

    Dobbins, Sean C; McGrath, Daniel E; Bernards, Matthew T

    2012-12-13

    A critical challenge in the field of biomaterials is the often undesirable, but immediate, coating of implants with nonspecifically adsorbed proteins upon contact with bodily fluids. Prior research has shown that overall neutral materials containing a homologous arrangement of mixed charges exhibit nonfouling properties. This has been widely demonstrated for zwitterionic materials and more recently for coatings containing an equimolar mixture of positively and negatively charged monomer subunits. In this investigation it is demonstrated that nonfouling hydrogels can be formed through this approach, and the physical properties of the resulting materials are thoroughly characterized. In particular, hydrogels were formed from mixtures of [2-(methacryloyloxy)ethyl]trimethylammonium chloride (TM) and 3-sulfopropyl methacrylate potassium salt (SA) monomers with varying concentrations of a triethylene glycol dimethacrylate (TEGDMA) cross-linker. The swelling, weight percentage water, surface zeta potential, and compressional properties of the gels were characterized, and the nonfouling properties were demonstrated using enzyme-linked immunosorbant assays for both negatively charged fibrinogen and positively charged lysozyme. The results confirm that the TM:SA hydrogel systems have nonfouling properties that are equivalent to established nonfouling controls. Additionally, even though the gels were resistant to nonspecific protein adsorption, a composition analysis suggests that there is room to further improve the nonfouling performance because there is a slight enrichment of the SA monomer relative to the TM monomer. PMID:23189949

  12. Radiation crosslinking of polymer materials and its functional properties

    International Nuclear Information System (INIS)

    It was found out that radiation crosslinking of biodegradable polymer such as poly (butylene succinate, PBS) and poly(ε-caprolactone, PCL) could be achieved by radiation in the presence of small amount of trimethallyl isocyanurate (TMAIC) or 1% triallyl isocyanurate (TAIC). Such modification is very effective to improve heat resistance for PBS and PCL. Poly (lactic acid, PLA) undergoes crosslinking effectively with 3% TAIC by radiation. Outstanding feature of these polymers is their biodegradability even after crosslinking. Radiation crosslinking of polysaccharide derivatives such as carboxymethyl-cellulose (CMC) is also achieved in aqueous solution at high concentration (paste-like state). The crosslinking behavior was largely affected by the degree of substitution (DS) and polymer concentration. After removal of water the dry CMC gel is used as water absorbent material. This dry gel is the most effective for removal of large amounts of water from organic wastes, resulting in the acceleration of their fermentation. Measurement of swelling ratio of the dry CMC gel in 0.9% NaCl aqueous solution was carried out to expand application fields for this material. Radiation crosslinked poly (vinyl alcohol) hydrogel was successfully commercialized from July 2004 as wound dressing for accelerated healing. Furthermore, this material was also used as gel protector to prevent shore sore and was further commercialized. (author)

  13. Injectable hydrogel as cell carriers: Mechanism of beta-hairpin peptide hydrogel shear thinning, immediate recovery and effects on encapsulated cell payload

    Science.gov (United States)

    Yan, Congqi

    To facilitate future biomedical treatment with localized delivery and higher therapy efficacy, much research effort has been devoted recently to the development of hydrogel biomaterials to transport a therapy to in vivo target sites via simple syringe or catheter injection. Most injectable hydrogel materials are free flowing precursor solutions ex vivo that become crosslinked into hydrogels once injected in vivo in response to exposure to environmental stimuli. However, properties of the final hydrogel formed in vivo are unpredictable due to possible leakage, dilution or change of injected gel precursor solution. As an alternate, more recent strategy for injectable hydrogel therapies, beta-hairpin peptide-based hydrogels are a class of injectable hydrogel solids with significant potential use in injectable therapies. These physical hydrogels can shear-thin and consequently flow as a low-viscosity material under a sufficient shear stress but immediately recover back into a solid upon removal of the stress, allowing them to be injected as preformed gel solids. The shear-thinning and immediate self-healing properties of self-assembled beta-hairpin peptide hydrogels enable a direct delivery of gel-encapsulated cells via benign injection to tissue defect sites with well-defined final gel properties in vivo. In this dissertation, mechanisms of gel shear-thinning and immediate recovery were elucidated by investigating gel behavior during and after flow via mechanical and structural characterizations. All studied beta-hairpin hydrogels shear-thin during flow (gel network fracture into large hydrogel domains) and instantly recover after cessation of flow (gel domains are percolated which immediately reforms the solid hydrogel). Importantly, hydrogel flow behavior was further studied in a capillary geometry that mimicked the actual situation of syringe injection. It was observed that all beta-hairpin peptide hydrogels investigated displayed a promising flow profile for

  14. Preparation of poly(polyethylene glycol methacrylate-co-acrylic acid) hydrogels by radiation and their physical properties[Radiation; pH-responsive; Hydrogels; Insulin; Oral delivery

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.-E.; Nho, Y.-C. E-mail: ycnho@kaeri.re.kr; Kim, H.-I

    2004-02-01

    The pH-responsive copolymer hydrogels were prepared with the monomers of polyethylene glycol methacrylate and acrylic acid based on {gamma}-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. Modified gum arabic cross-linked gelatin scaffold for biomedical applications

    International Nuclear Information System (INIS)

    The present work deals with development of modified gum arabic cross-linked gelatin scaffold for cell culture. A new biocompatible scaffold was developed by cross-linking gelatin (Gel) with gum arabic, a polysaccharide. Gum arabic was subjected to periodate oxidation to obtain gum arabic aldehyde (GAA). GAA was reacted with gelatin under appropriate pH to prepare the cross-linked hydrogel. Cross-linking occurred due to Schiff's base reaction between aldehyde groups of oxidized gum arabic and amino groups of gelatin. The scaffold prepared from the hydrogel was characterized by swelling properties, degree of cross-linking, in vitro degradation and scanning electron microscopy (SEM). Cytocompatibility evaluation using L-929 and HepG2 cells confirmed non-cytotoxic and non-adherent nature of the scaffold. These properties are essential for generating multicellular spheroids and hence the scaffold is proposed to be a suitable candidate for spheroid cell culture. - Highlights: • Gum arabic cross-linked gelatin scaffold was developed for tissue engineering. • Cross-linking was achieved by Schiff's base reaction. • The scaffold is non-cytotoxic and non adherent to fibroblast and hepatocytes. • The scaffolds are potential candidates for spheroid cell culture

  16. Modified gum arabic cross-linked gelatin scaffold for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sarika, P.R. [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram, Kerala 695 547 (India); Cinthya, Kuriakose [Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Thiruvananthapuram, Kerala 695 012 (India); Jayakrishnan, A. [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036 (India); Anilkumar, P.R., E-mail: anilkumarpr@sctimst.ac.in [Tissue Culture Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Poojappura, Thiruvananthapuram, Kerala 695 012 (India); James, Nirmala Rachel, E-mail: nirmala@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram, Kerala 695 547 (India)

    2014-10-01

    The present work deals with development of modified gum arabic cross-linked gelatin scaffold for cell culture. A new biocompatible scaffold was developed by cross-linking gelatin (Gel) with gum arabic, a polysaccharide. Gum arabic was subjected to periodate oxidation to obtain gum arabic aldehyde (GAA). GAA was reacted with gelatin under appropriate pH to prepare the cross-linked hydrogel. Cross-linking occurred due to Schiff's base reaction between aldehyde groups of oxidized gum arabic and amino groups of gelatin. The scaffold prepared from the hydrogel was characterized by swelling properties, degree of cross-linking, in vitro degradation and scanning electron microscopy (SEM). Cytocompatibility evaluation using L-929 and HepG2 cells confirmed non-cytotoxic and non-adherent nature of the scaffold. These properties are essential for generating multicellular spheroids and hence the scaffold is proposed to be a suitable candidate for spheroid cell culture. - Highlights: • Gum arabic cross-linked gelatin scaffold was developed for tissue engineering. • Cross-linking was achieved by Schiff's base reaction. • The scaffold is non-cytotoxic and non adherent to fibroblast and hepatocytes. • The scaffolds are potential candidates for spheroid cell culture.

  17. In situ forming, metal-adhesive heparin hydrogel surfaces for blood-compatible coating.

    Science.gov (United States)

    Joung, Yoon Ki; You, Seung Soo; Park, Kyung Min; Go, Dong Hyun; Park, Ki Dong

    2012-11-01

    Durable and blood-compatible coating of metallic biomaterials remains a major issue in biomedical fields despite its long history of development. In this study, in situ forming, metal-adhesive heparin hydrogels were developed to coat metallic substrates to enhance blood compatibility. The hydrogels are composed of metal-adhesive and enzyme-reactive amphiphilic block copolymer (Tetronic-tyramine/dopamine; TTD) and enzyme-reactive heparin derivatives (heparin-tyramine or heparin-polyethylene glycol-tyramine), which are cross-linkable in situ via an enzyme reaction. The combinations of heparin and Tetronic formed hydrogels with relatively high mechanical strengths of 300-5000 Pa within several tens of seconds; this was also confirmed by observing a dried porous structure as coated on a metal surface. The introduction of dopamine to the hydrogel network enhanced the durability of the hydrogel layers coated on metal, such that more than 60% heparin remained for 7 days. Compared to bare metal surfaces, hydrogel-coated metal surfaces exhibited significantly enhanced blood compatibility. Reduced fibrinogen adsorption and platelet adhesion showed that blood compatibility was 3-5-fold-enhanced on coated hydrogel layers than on the bare metal surface. In conclusion, hydrogels containing heparin and dopamine prepared by enzyme reaction have the potential to be an alternative coating method for enhancing blood compatibility of metallic biomaterials. PMID:22100384

  18. Development of carboxymethyl cellulose-based hydrogel and nanosilver composite as antimicrobial agents for UTI pathogens.

    Science.gov (United States)

    Alshehri, Saad M; Aldalbahi, Ali; Al-Hajji, Abdullah Baker; Chaudhary, Anis Ahmad; Panhuis, Marc In Het; Alhokbany, Norah; Ahamad, Tansir

    2016-03-15

    Silver nanoparticles (AgNPs) containing hydrogel composite were first synthesized by preparing a new hydrogel from carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and the cross-linker ethylene glycol diglycidyl ether (EGDE), followed by the incorporation of AgNPs by microwave radiation. The resulting neat hydrogels and AgNPs-hydrogel composites were characterized using spectral, thermal, microscopic analysis and X-ray diffraction (XRD) analyses. The SEM and TEM results demonstrated that the synthesized AgNPs were spherical with diameters ranging from 8 to 14nm. In addition, the XRD analysis confirmed the nanocrystalline phase of silver with face-centered cubic (FCC) crystal structure. Energy dispersive spectroscopy (EDS) analysis of the AgNPs confirmed the presence of an elemental silver signal, and no peaks of any other impurities were detected. Additionally, the antibacterial activities of the neat hydrogel and AgNPs-hydrogel composites were measured by Kirby-Bauer method against urinary tract infection (UTI) pathogens. The rheology measurement revealed that the values of storage modulus (G') were higher than that of loss modulus (G″). The AgNPs-hydrogel composites exhibited higher antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris, Staphylococcus aureus and Proteus mirabilis compared to the corresponding neat hydrogel. PMID:26794757

  19. Sericin/Dextran Injectable Hydrogel as an Optically Trackable Drug Delivery System for Malignant Melanoma Treatment.

    Science.gov (United States)

    Liu, Jia; Qi, Chao; Tao, Kaixiong; Zhang, Jinxiang; Zhang, Jian; Xu, Luming; Jiang, Xulin; Zhang, Yunti; Huang, Lei; Li, Qilin; Xie, Hongjian; Gao, Jinbo; Shuai, Xiaoming; Wang, Guobin; Wang, Zheng; Wang, Lin

    2016-03-01

    Severe side effects of cancer chemotherapy prompt developing better drug delivery systems. Injectable hydrogels are an effective site-target system. For most of injectable hydrogels, once delivered in vivo, some properties including drug release and degradation, which are critical to chemotherapeutic effects and safety, are challenging to monitor. Developing a drug delivery system for effective cancer therapy with in vivo real-time noninvasive trackability is highly desired. Although fluorescence dyes are used for imaging hydrogels, the cytotoxicity limits their applications. By using sericin, a natural photoluminescent protein from silk, we successfully synthesized a hydrazone cross-linked sericin/dextran injectable hydrogel. This hydrogel is biodegradable and biocompatible. It achieves efficient drug loading and controlled release of both macromolecular and small molecular drugs. Notably, sericin's photoluminescence from this hydrogel is directly and stably correlated with its degradation, enabling long-term in vivo imaging and real-time monitoring of the remaining drug. The hydrogel loaded with Doxorubicin significantly suppresses tumor growth. Together, the work demonstrates the efficacy of this drug delivery system, and the in vivo effectiveness of this sericin-based optical monitoring strategy, providing a potential approach for improving hydrogel design toward optimal efficiency and safety of chemotherapies, which may be widely applicable to other drug delivery systems. PMID:26900631

  20. Synthesis and characterization of a new photo-crosslinkable glycol chitosan thermogel for biomedical applications.

    Science.gov (United States)

    Cho, Ik Sung; Cho, Myeong Ok; Li, Zhengzheng; Nurunnabi, Md; Park, Sung Young; Kang, Sun-Woong; Huh, Kang Moo

    2016-06-25

    The major limitations of typical thermogelling polymers for practical applications are low gel stability and weak mechanical properties under physiological conditions. In this study, we have synthesized a new polysaccharide-based thermogelling polymer that can be photo-crosslinked by UV irradiation to form a mechanically resilient and elastic hydrogel. Methacrylated hexanoyl glycol chitosan (M-HGC), was synthesized by a series of chemical modifications, N-hexanoylation and N-methacrylation, of glycol chitosan (GC). Various M-HGC polymers with different methacryl group contents were synthesized and their thermogelling and photo-crosslinkable properties were evaluated. The M-HGCs demonstrated a thermo-reversible sol-gel transition behavior in aqueous solutions. The thermally-induced hydrogels could be chemically crosslinked by UV-triggered photo-crosslinking. From the cytotoxicity studies using MTT and the live/dead assay, the M-HGC hydrogels showed non-cytotoxicity. These photo-crosslinkable thermogelling M-HGC polymers may hold great promises for various biomedical applications, such as an injectable delivery system and 3D cell culture. PMID:27083793

  1. Tuning nanoscale viscoelasticity of polyelectrolyte complexes with multiple types of cross-links

    Science.gov (United States)

    Ma, Tianzhu; Han, Biao; Lee, Daeyeon; Han, Lin

    Mechanical properties of hydrogels are manifestation of cross-link type and density, fixed charges and water-polymer interactions. In this study, we revealed how different types of cross-links regulate the nanoscale viscoelasticity of polyelectrolyte networks. Ionically cross-linked PAH/PAA layer-by-layer complexes were modified to include covalent cross-links using EDC. AFM-nanoindentation and force relaxation were performed at various ionic strength (0.01-1M) and pH (1.5-5.5). As-assembled networks, held only by ionic cross-links, underwent >95% relaxation, dominated by cross-link breaking and re-formation. Addition of covalent cross-links increased the instantaneous modulus by 1.6-fold and attenuated relaxation to ~80% of net neutral states (pH >=3.5), as covalent cross-links provide additional elastic components. The network remained stabilized when all ionic cross-links were dissociated at pH poroelasticity. Taken together, this study demonstrates the potential of using multiple cross-linking types to tune the viscoelastic mechanisms in polyelectrolyte complexes.

  2. Carboxymethyl starch cross-linked by electron beam radiation in presence of acrylic acid sensitizer

    International Nuclear Information System (INIS)

    Carboxymethyl starch (CMS) can be cross-linked by electron beam radiation to form a biocompatible and environment-friendly hydrogel at a high absorbed dose and a condensed CMS concentration. Acrylic acid (AAc) can be used as a sensitizer in order to reduce the absorbed doses to an acceptable certain level. At an absorbed dose of 3-4 kGy, the gel content of crosslinked CMS can be obtained about 50% with 5% (w/w) AAc concentration used. The compressive strength of CMS samples increased with increasing their cross-linked densities due to raising absorbed doses. The swelling ratio of cross-linked CMS was also attainable at a maximum of 50 times in the distilled water. The enzymatic degradation of cross-linked CMS was carried out in acetate buffer pH 4.6 with 0.1% α-amylase enzymatic solution incubated at 40℃ for 6 h. The crosslinked CMS samples were degraded slower than uncrosslinked CMS ones. The results indicated that the highly cross-linked CMS was almost fully degradable when the enzymatic hydrolysis was performed during 6 h. The FT IR spectra of cross-linked CMS in the presence of AAc were examined to observe the carboxyl group of AAc in the structure of cross-linked CMS. The hydrophilic of cross-linked CMS surface was determined by a contact-angle analysis. (authors)

  3. Experimental Investigation of Mechanical and Thermal Properties of Silica Nanoparticle-Reinforced Poly(acrylamide) Nanocomposite Hydrogels.

    Science.gov (United States)

    Zaragoza, Josergio; Babhadiashar, Nasim; O'Brien, Victor; Chang, Andrew; Blanco, Matthew; Zabalegui, Aitor; Lee, Hohyun; Asuri, Prashanth

    2015-01-01

    Current studies investigating properties of nanoparticle-reinforced polymers have shown that nanocomposites often exhibit improved properties compared to neat polymers. However, over two decades of research, using both experimental studies and modeling analyses, has not fully elucidated the mechanistic underpinnings behind these enhancements. Moreover, few studies have focused on developing an understanding among two or more polymer properties affected by incorporation of nanomaterials. In our study, we investigated the elastic and thermal properties of poly(acrylamide) hydrogels containing silica nanoparticles. Both nanoparticle concentration and size affected hydrogel properties, with similar trends in enhancements observed for elastic modulus and thermal diffusivity. We also observed significantly lower swellability for hydrogel nanocomposites relative to neat hydrogels, consistent with previous work suggesting that nanoparticles can mediate pseudo crosslinking within polymer networks. Collectively, these results indicate the ability to develop next-generation composite materials with enhanced mechanical and thermal properties by increasing the average crosslinking density using nanoparticles. PMID:26301505

  4. Experimental Investigation of Mechanical and Thermal Properties of Silica Nanoparticle-Reinforced Poly(acrylamide Nanocomposite Hydrogels.

    Directory of Open Access Journals (Sweden)

    Josergio Zaragoza

    Full Text Available Current studies investigating properties of nanoparticle-reinforced polymers have shown that nanocomposites often exhibit improved properties compared to neat polymers. However, over two decades of research, using both experimental studies and modeling analyses, has not fully elucidated the mechanistic underpinnings behind these enhancements. Moreover, few studies have focused on developing an understanding among two or more polymer properties affected by incorporation of nanomaterials. In our study, we investigated the elastic and thermal properties of poly(acrylamide hydrogels containing silica nanoparticles. Both nanoparticle concentration and size affected hydrogel properties, with similar trends in enhancements observed for elastic modulus and thermal diffusivity. We also observed significantly lower swellability for hydrogel nanocomposites relative to neat hydrogels, consistent with previous work suggesting that nanoparticles can mediate pseudo crosslinking within polymer networks. Collectively, these results indicate the ability to develop next-generation composite materials with enhanced mechanical and thermal properties by increasing the average crosslinking density using nanoparticles.

  5. Dimensionality and spreading influence MSC YAP/TAZ signaling in hydrogel environments.

    Science.gov (United States)

    Caliari, Steven R; Vega, Sebastián L; Kwon, Michelle; Soulas, Elizabeth M; Burdick, Jason A

    2016-10-01

    Improved fundamental understanding of how cells interpret microenvironmental signals is integral to designing better biomaterial therapies. YAP/TAZ are key mediators of mechanosensitive signaling; however, it is not clear how they are regulated by the complex interplay of microenvironmental factors (e.g., stiffness and degradability) and culture dimensionality. Using covalently crosslinked norbornene-functionalized hyaluronic acid (HA) hydrogels with controlled stiffness (via crosslink density) and degradability (via susceptibility of crosslinks to proteolysis), we found that human mesenchymal stem cells (MSCs) displayed increased spreading and YAP/TAZ nuclear localization when cultured atop stiffer hydrogels; however, the opposite trend was observed when MSCs were encapsulated within degradable hydrogels. When stiffness-matched hydrogels of reduced degradability were used, YAP/TAZ nuclear translocation was greater in cells that were able to spread, which was confirmed through pharmacological inhibition of YAP/TAZ and actin polymerization. Together, these data illustrate that YAP/TAZ signaling is responsive to hydrogel stiffness and degradability, but the outcome is dependent on the dimensionality of cell-biomaterial interactions. PMID:27429252

  6. 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.

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

    International Nuclear Information System (INIS)

    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

  8. 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.

  9. Research on the friction and wear mechanism of Poly(vinyl alcohol)/hydroxylapatite composite hydrogel

    Institute of Scientific and Technical Information of China (English)

    ZHANG DeKun; SHEN YanQiu; GE ShiRong

    2009-01-01

    Poly(vinyl alcohol)/Hydroxylapatite(PVA/HA)composite hydrogel was prepared with poly(vinyl alcohol)and hydroxylapatite as raw materials,using the method of repeated freezing and thawing.The morphologies of PVA/HA composite hydrogel were observed by means of high-accuracy 3D profiler and scanning electron microscope(SEM).The compressive elastic modulus and the stress relaxation characteristics of PVA/HA composite hydrogel were measured using the flat-head cylinder indenter.The friction and wear tests between PVA/HA composite hydrogel and bovine knee articular cartilage were performed on the micro-tribometer.The worn morphologies of PVA/HA composite hydrogel were observed with environmental scanning electron microscope(ESEM).The results showed that PVA/HA composite hydrogel has the cross-link network microstructure which is similar to that of the natural bovine knee articular cartilages.With the increase of freezing-thawing cycles and the HA content,the degree of cross-link and the crystallization of PVA/HA composite hydrogel both increase,the elastic modulus increases evidently,the rate of stress relaxation is improved and the value of balance stress decreases.The friction coefficient decreases with the increase of the freezing-thawing cycles and the HA content.The more the freezing-thawing cycles are,the earlier the friction coefficient reaches the stable balance value.The friction deformation depth between PVA/HA composite hydrogel and bovine knee articular cartilage is inversely proportional to freezing-thawing cycles and the HA content.The main wear mechanisms of PVA/HA composite hydrogel are plastic flowing and adhesive flaking.The wear severity degree decreases with the increase of freezing-thawing cycles and the HA content.

  10. Research on the friction and wear mechanism of Poly(vinyl alcohol)/hydroxylapatite composite hydrogel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Poly(vinyl alcohol)/Hydroxylapatite(PVA/HA) composite hydrogel was prepared with poly(vinyl alcohol) and hydroxylapatite as raw materials, using the method of repeated freezing and thawing.The morphologies of PVA/HA composite hydrogel were observed by means of high-accuracy 3D profiler and scanning electron microscope(SEM).The compressive elastic modulus and the stress relaxation characteristics of PVA/HA composite hydrogel were measured using the flat-head cylinder indenter.The friction and wear tests between PVA/HA composite hydrogel and bovine knee articular cartilage were performed on the micro-tribometer.The worn morphologies of PVA/HA composite hydrogel were observed with environmental scanning electron microscope(ESEM).The results showed that PVA/HA composite hydrogel has the cross-link network microstructure which is similar to that of the natural bovine knee articular cartilages.With the increase of freezing-thawing cycles and the HA content, the degree of cross-link and the crystallization of PVA/HA composite hydrogel both increase, the elastic modulus increases evidently, the rate of stress relaxation is improved and the value of balance stress decreases.The friction coefficient decreases with the increase of the freezing-thawing cycles and the HA content.The more the freezing-thawing cycles are, the earlier the friction coefficient reaches the stable balance value.The friction deformation depth between PVA/HA composite hydrogel and bovine knee articular cartilage is inversely proportional to freezing-thawing cycles and the HA content.The main wear mechanisms of PVA/HA composite hydrogel are plastic flowing and adhesive flaking.The wear severity degree decreases with the increase of freezing-thawing cycles and the HA content.

  11. Supressed Water Crystallization in Nano-Structured Physical Hydrogel

    Science.gov (United States)

    Wiener, Clinton; Vogt, Bryan; Weiss, Robert

    2015-03-01

    Suppressed water crystallization occurs in some organisms, such as the common wood frog, which allows it to hibernate in a frozen state without damage to its cells. Knowledge of the behavior of supercooled water and alternate ice forms may have many implications to many fields of science. Supercooling of water by several degrees below the normal freezing point is often observed in hydrogels that have attractive interactions with water, e.g., hydrogen bonding. Repulsive confinement, such as in hydrophobic porous carbon, can have even more significant effects on the supercooling of the entrapped water. This talk describes the freezing behavior in nano-structured, hydrophobically modified poly(dimethyl acrylamide) hydrogels that possess attractive and repulsive interactions with water and are physically crosslinked by hydrophobic nanodomains. Three distinct water freezing regimes were observed in the hydrogel swollen to about 50% water by weight. Differential scanning calorimetry detected three crystallization exotherms at 254K, 244K, and 227K. Quasi-elastic neutron scattering experiments have shown that although the water mobility was suppressed at room temperature, the water remained significantly mobile below the normal freezing point of water. The talk will discuss how tuning the concentration of the hydrophobic composition of the hydrogel affects the porous length scales in the hydrogel, which may alter the state of water and the crystal form produced by supercooling.

  12. Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

    International Nuclear Information System (INIS)

    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

  13. 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.

  14. Controlling Hydrogel Mechanics via Bio-Inspired Polymer-Nanoparticle Bond Dynamics.

    Science.gov (United States)

    Li, Qiaochu; Barrett, Devin G; Messersmith, Phillip B; Holten-Andersen, Niels

    2016-01-26

    Interactions between polymer molecules and inorganic nanoparticles can play a dominant role in nanocomposite material mechanics, yet control of such interfacial interaction dynamics remains a significant challenge particularly in water. This study presents insights on how to engineer hydrogel material mechanics via nanoparticle interface-controlled cross-link dynamics. Inspired by the adhesive chemistry in mussel threads, we have incorporated iron oxide nanoparticles (Fe3O4 NPs) into a catechol-modified polymer network to obtain hydrogels cross-linked via reversible metal-coordination bonds at Fe3O4 NP surfaces. Unique material mechanics result from the supra-molecular cross-link structure dynamics in the gels; in contrast to the previously reported fluid-like dynamics of transient catechol-Fe(3+) cross-links, the catechol-Fe3O4 NP structures provide solid-like yet reversible hydrogel mechanics. The structurally controlled hierarchical mechanics presented here suggest how to develop hydrogels with remote-controlled self-healing dynamics. PMID:26645284

  15. Rate-controlled rectal drug delivery in man with a hydrogel preparation

    NARCIS (Netherlands)

    Leede, de L.G.J.; Boer, de A.G.; Pörtzgen, E.; Feijen, J.; Breimer, D.D.

    1986-01-01

    Cylindrical hydrogels of hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent were prepared by radical polymerization at 70°C. After washing they were soaked in an aqueous drug solution of antipyrine or theophylline. The in vitro drug release experiments

  16. Stimuli response of polysoap hydrogels in aqueous solution and DC electric fields

    NARCIS (Netherlands)

    Yang, Yajiang; Engberts, Jan B.F.N.

    2000-01-01

    Novel types of polysoap hydrogels based on hydrophobically-modified polyelectrolytes crosslinked with N,N-methylenebisacrylamide have been prepared by free radical polymerization at 70–80°C in aqueous solution with ammonium persulfate as initiator. Poly(diallylamine-co-N,N-dodecylmethyldiallylammoni

  17. Evaluation of a polyacrylamide hydrogel in the treatment of induced osteoarthritis in a goat model

    DEFF Research Database (Denmark)

    Tnibar, Aziz; Persson, Ann; Jensen, Henrik Elvang;

    2014-01-01

    Polyacrylamide hydrogel (PAAG) is an inert, non-degradable, non-immunogenic polymer gel with high viscoelasticity consisting of 97.5% sterile water and 2.5% cross-linked polyacrylamide. Its biocompatibility in soft tissues has been demonstrated. PAAG has recently been tested for the treatment...

  18. Myocardial matrix–polyethylene glycol hybrid hydrogels for tissue engineering

    International Nuclear Information System (INIS)

    Similar to other protein-based hydrogels, extracellular matrix (ECM) based hydrogels, derived from decellularized tissues, have a narrow range of mechanical properties and are rapidly degraded. These hydrogels contain natural cellular adhesion sites, form nanofibrous networks similar to native ECM, and are biodegradable. In this study, we expand the properties of these types of materials by incorporating poly(ethylene glycol) (PEG) into the ECM network. We use decellularized myocardial matrix as an example of a tissue specific ECM derived hydrogel. Myocardial matrix–PEG hybrids were synthesized by two different methods, cross-linking the proteins with an amine-reactive PEG-star and photo-induced radical polymerization of two different multi-armed PEG-acrylates. We show that both methods allow for conjugation of PEG to the myocardial matrix by gel electrophoresis and infrared spectroscopy. Scanning electron microscopy demonstrated that the hybrid materials still contain a nanofibrous network similar to unmodified myocardial matrix and that the fiber diameter is changed by the method of PEG incorporation and PEG molecular weight. PEG conjugation also decreased the rate of enzymatic degradation in vitro, and increased material stiffness. Hybrids synthesized with amine-reactive PEG had gelation rates of 30 min, similar to the unmodified myocardial matrix, and incorporation of PEG did not prevent cell adhesion and migration through the hydrogels, thus offering the possibility to have an injectable ECM hydrogel that degrades more slowly in vivo. The photo-polymerized radical systems gelled in 4 min upon irradiation, allowing 3D encapsulation and culture of cells, unlike the soft unmodified myocardial matrix. This work demonstrates that PEG incorporation into ECM-based hydrogels can expand material properties, thereby opening up new possibilities for in vitro and in vivo applications. (paper)

  19. Synthesis, characterization and application of biodegradable crosslinked carboxymethyl chitosan/poly(vinyl alcohol) clay nanocomposites.

    Science.gov (United States)

    Sabaa, Magdy W; Abdallah, Heba M; Mohamed, Nadia A; Mohamed, Riham R

    2015-11-01

    Crosslinked poly(vinyl alcohol) (PVA)/carboxymethyl chitosan (CMCh) nanocomposites were synthesized using terephthaloyl diisothiocyanate crosslinker, in the presence of montmorillonite (MMT), in different ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PVA hydrogels increased the swellability. Metal ion adsorption has also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non crosslinked CMCh. Antimicrobial activity was examined against Gram positive bacteria, against Gram negative bacteria, and also against fungi. Results indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation study was carried out in Simulated Body Fluid (SBF) for different time periods in order to find out degradation index (Di). Results showed that weight loss of most of the nanocomposites increased as a function of incubation time. PMID:26249602

  20. Integrating Valve-Inspired Design Features Into Poly(ethylene glycol) Hydrogel Scaffolds For Heart Valve Tissue Engineering

    OpenAIRE

    Zhang, Xing; Xu, Bin; Puperi, Daniel S.; Yonezawa, Aline L.; Wu, Yan; Tseng, Hubert; Cuchiara, Maude L.; West, Jennifer L.; Grande-Allen, K. Jane

    2014-01-01

    The development of advanced scaffolds that recapitulate the anisotropic mechanical behavior and biological functions of the extracellular matrix in leaflets would be transformative for heart valve tissue engineering. In this study, anisotropic mechanical properties were established in poly(ethylene glycol) (PEG) hydrogels by crosslinking stripes of 3.4 kDa PEG diacrylate (PEGDA) within 20 kDa PEGDA base hydrogels using a photolithographic patterning method. Varying the stripe width and spacin...

  1. Exogenously Triggered, Enzymatic Degradation of Photopolymerized Hydrogels With Polycaprolactone Subunits: Experimental Observation and Modeling of Mass Loss Behavior

    OpenAIRE

    Rice, Mark A.; Sanchez-Adams, Johannah; Anseth, Kristi S.

    2006-01-01

    Degradation plays an important role in the evolution of extracellular matrix secreted by chondrocytes encapsulated in PEG-based hydrogels. For this study, macromonomers were synthesized by methacrylating both ends of polycaprolactone-b-poly(ethylene glycol)-b-polycaprolactone (PEG-CAP) tri-block copolymers. These divinyl molecules were photopolymerized to form hydrogels with PEG-CAP crosslinks that were subsequently degraded upon exogenous addition of a lipase enzyme. The rate of degradation ...

  2. FGF-1 and proteolytically-mediated cleavage site presentation influence 3D fibroblast invasion in biomimetic PEGDA hydrogels

    OpenAIRE

    Sokic, Sonja; Papavasiliou, Georgia

    2012-01-01

    Controlled scaffold degradation is a critical design criterion for the clinical success of tissue engineered constructs. Here, we exploited a biomimetic poly(ethylene glycol) diacrylate (PEGDA) hydrogel system immobilized with tethered YRGDS as the cell adhesion ligand and with either single (SSite) or multiple (MSite) collagenase-sensitive domains between crosslinks, to systematically study the effect of proteolytic cleavage site presentation on hydrogel degradation rate and 3D fibroblast in...

  3. Ophthalmic drug-loaded N,O-carboxymethyl chitosan hydrogels: synthesis, in vitro and in vivo evaluation

    OpenAIRE

    Yang, Li-Qun; Lan, Yu-qing; Guo, Hui; Cheng, Liang-zheng; Fan, Ji-zhou; Cai, Xiang; Zhang, Li-Ming; Chen, Ru-Fu; Zhou, Huai-sheng

    2010-01-01

    Aim: To investigate the ability of drug-loaded N,O-carboxymethyl chitosan (CMCS) hydrogels to modulate wound healing after glaucoma filtration surgery. Methods: The drug-loaded CMCS hydrogels were in situ synthesized using genipin as the crosslinker in the presence of 5-fluorouracil (5FU) or bevacizumab. Their structures were characterized by FTIR, ultraviolet-visible (UV-vis) spectroscopy and scanning electron microscopy (SEM). In-vitro drug release experiments and in vivo evaluation in rabb...

  4. Controlled Release of Simvastatin from In situ Forming Hydrogel Triggers Bone Formation in MC3T3-E1 Cells

    OpenAIRE

    Park, Yoon Shin; David, Allan E.; Park, Kyung Min; Lin, Chia-Ying; Than, Khoi D.; Lee, Kyuri; Park, Jun Beom; Jo, Inho; Park, Ki Dong; Yang, Victor C.

    2012-01-01

    Simvastatin (SIM), a drug commonly administered for the treatment of hypercholesterolemia, has been recently reported to induce bone regeneration/formation. In this study, we investigated the properties of hydrogel composed of gelatin–poly(ethylene glycol)–tyramine (GPT) as an efficient SIM delivery vehicle that can trigger osteogenic differentiation. Sustained delivery of SIM was achieved through its encapsulation in an injectable, biodegradable GPT-hydrogel. Cross-linking of the gelatin-bas...

  5. Exploring natural silk protein sericin for regenerative medicine: an injectable, photoluminescent, cell-adhesive 3D hydrogel

    OpenAIRE

    Wang, Zheng; Zhang, Yeshun; Zhang, Jinxiang; Huang, Lei; Liu, Jia; Li, Yongkui; Zhang, Guozheng; Kundu, Subhas C.; Wang, Lin

    2014-01-01

    Sericin, a major component of silk, has a long history of being discarded as a waste during silk processing. The value of sericin for tissue engineering is underestimated and its potential application in regenerative medicine has just begun to be explored. Here we report the successful fabrication and characterization of a covalently-crosslinked 3D pure sericin hydrogel for delivery of cells and drugs. This hydrogel is injectable, permitting its implantation through minimally invasive approac...

  6. Bioactive factor delivery strategies from engineered polymer hydrogels for therapeutic medicine.

    Science.gov (United States)

    Nguyen, Minh Khanh; Alsberg, Eben

    2014-07-01

    Polymer hydrogels have been widely explored as therapeutic delivery matrices because of their ability to present sustained, localized and controlled release of bioactive factors. Bioactive factor delivery from injectable biopolymer hydrogels provides a versatile approach to treat a wide variety of diseases, to direct cell function and to enhance tissue regeneration. The innovative development and modification of both natural-(e.g., alginate (ALG), chitosan, hyaluronic acid (HA), gelatin, heparin (HEP), etc.) and synthetic-(e.g., polyesters, polyethyleneimine (PEI), etc.) based polymers has resulted in a variety of approaches to design drug delivery hydrogel systems from which loaded therapeutics are released. This review presents the state-of-the-art in a wide range of hydrogels that are formed though self-assembly of polymers and peptides, chemical crosslinking, ionic crosslinking and biomolecule recognition. Hydrogel design for bioactive factor delivery is the focus of the first section. The second section then thoroughly discusses release strategies of payloads from hydrogels for therapeutic medicine, such as physical incorporation, covalent tethering, affinity interactions, on demand release and/or use of hybrid polymer scaffolds, with an emphasis on the last 5 years. PMID:25242831

  7. Synthesis and characterization of polycaprolactone/acrylic acid (PCL/AA) hydrogel for controlled drug delivery

    Indian Academy of Sciences (India)

    Nazar Mohammad Ranjha; Jahanzeb Mudassir; Sajid Majeed

    2011-12-01

    In the present work biodegradable pH-sensitive polycaprolactone/acrylic acid (PCL/AA) hydrogels have been developed using ethylene glycol dimethacrylate (EGDMA) as a cross-linker and benzoyl peroxide as initiator. For these prepared hydrogels swelling studies, sol–gel fraction analysis and porosity measurements were performed. Results show that swelling of the hydrogels decreases on increasing the concentration of PCL and EGDMA, however swelling of hydrogels increases on increasing the concentration of AA. Results of sol–gel fraction analysis show that gel fraction increases on increasing concentration of monomer AA, polymer PCL as well as cross-linker EGDMA. As far as porosity is concerned, it increases on increasing the concentration of AA and PCL while porosity decreases on increasing the concentration of EGDMA. Hydrogels were characterized by measuring diffusion coefficient () and equilibrium water content (EWC). Network formation, morphology and crystallinity of PCL/AA hydrogels were investigated using FTIR, SEM and XRD, respectively. Tramadol hydrochloride was loaded as model drug and its release pattern was analysed using various kinetic models like zero order, first order, Higuchi and Peppas. Results indicated that most of the samples followed non-Fickian release mechanism.

  8. Radiation synthesis of hydrogels with diprotic acid moieties and their use in the adsorption of biomolecules

    International Nuclear Information System (INIS)

    Radiation synthesis of diprotic acid moieties containing poly (N-vinyl 2- pyrrolidone) and polyacrylamide hydrogels and their use in the adsorption of biomolecules such as enzymes, proteins and drugs have been investigated. Hydrogels with varying cross-linked densities and ionic moieties were prepared from the ternary systems of N-vinyl 2-pyrrolidone/itaconic acid/water and acrylamide/maleic acid/water by irradiating with γ rays at ambient temperature. For the characterization of network structure of hydrogels new equations were derived. Determination of average molecular weight between cross-links of hydrogels sensitive to pH changes of the swelling medium was investigated. In order to explain the influence of other external stimuli such as temperature and ionic strength of the swelling medium and the type of the buffer solution on the equilibrium swelling properties were investigated. The effect of these external stimuli on the biomolecule adsorption capacity of hydrogels were investigated for bovine serum albumin, α-amylase, invertase, model and commercial drugs. The results show that the hydrogels prepared in this study can be considered as potential carriers for the biomolecules and the drug delivery systems. (author)

  9. Chondrocyte Cultivationin Hyaluronan-Tyramine Cross-Linked Hydrogel

    Czech Academy of Sciences Publication Activity Database

    Kučera, L.; Weinfurterová, R.; Dvořáková, J.; Kučera, J.; Pravda, M.; Foglarová, M.; Svik, K.; Klein, P.; Velebný, V.; Kubala, Lukáš

    2015-01-01

    Roč. 64, č. 13 (2015), s. 661-674. ISSN 0091-4037 Institutional support: RVO:68081707 Keywords : Biocompatibility * hyaluronate * scaffold Subject RIV: BO - Biophysics Impact factor: 3.568, year: 2014

  10. Precise tailoring of tyramine-based hyaluronan hydrogel properties using DMTMM conjugation.

    Science.gov (United States)

    Loebel, Claudia; D'Este, Matteo; Alini, Mauro; Zenobi-Wong, Marcy; Eglin, David

    2015-01-22

    Injectable tyramine modified hyaluronic acid (HA-Tyr) hydrogels which are bio-orthogonally cross-linked with horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) are excellent candidate biomaterials for drug delivery, regenerative medicine and tissue engineering. Ligation of tyramine to HA has been reported using the very well established N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) chemistry. Here we demonstrate the applicability of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) as an alternative coupling agent to synthesize HA-Tyr conjugates. The optimized derivatization process allows accurate control of the degree of substituted Tyr on hyaluronan (DSmol). Hence, viscoelastic properties, in vitro swelling and enzymatic digestion profiles of the crosslinked hydrogels can be precisely tuned via DSmol. Our study demonstrates the advantages of DMTMM conjugation as a powerful tool to synthesize HA-Tyr hydrogels with properties exactly tailored for biomedical applications. PMID:25439901

  11. Self-Healing Nanocomposite Hydrogel with Well-Controlled Dynamic Mechanics

    Science.gov (United States)

    Li, Qiaochu; Mishra, Sumeet; Chen, Pangkuan; Tracy, Joseph; Holten-Andersen, Niels

    Network dynamics is a crucial factor that determines the macroscopic self-healing rate and efficiency in polymeric hydrogel materials, yet its controllability is seldom studied in most reported self-healing hydrogel systems. Inspired by mussel's adhesion chemistry, we developed a novel approach to assemble inorganic nanoparticles and catechol-decorated PEG polymer into a hydrogel network. When utilized as reversible polymer-particle crosslinks, catechol-metal coordination bonds yield a unique gel network with dynamic mechanics controlled directly by interfacial crosslink structure. Taking advantage of this structure-property relationship at polymer-particle interfaces, we next designed a hierarchically structured hybrid gel with two distinct relaxation timescales. By tuning the relative contribution of the two hierarchical relaxation modes, we are able to finely control the gel's dynamic mechanical behavior from a viscoelastic fluid to a stiff solid, yet preserving its fast self-healing property without the need for external stimuli.

  12. Design, synthesis and characterization of a novel pH-sensitive hydrogel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel degradable pH-sensitive hydrogel with pendent carboxyl groups was designed and synthesized from ethylenediami-netetraacetic dianhydride (EDTAh) and butanediamine (BDA) with dicyclohexylcarbodiimide (DCC) as a condensating agent and BDA as a crosslinking agent. The obtained polymers were characterized by 13C NMR, 1H NMR and FTIR. The swelling experiments of the hydrogel in pH 3, 7, and 12 media indicated much higher swelling ratio in pH 12 media than in pH 3 and pH 7 media, exhibiting sound pH sensitivity. The pH sensitivity of this type of hydrogel may be regulated through controlling the type and the dose of the crosslinking agent.

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

    International Nuclear Information System (INIS)

    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

  14. Organic hydrogels as potential sorbent materials for water purification

    Science.gov (United States)

    Linardatos, George; Bekiari, Vlasoula; Bokias, George

    2014-05-01

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

  15. PVNO-DVB hydrogels: synthesis and characterization. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hasirci, V.N.

    1982-01-01

    Hydrogels with various degrees of crosslinking were synthesized from 2-vinylpyridine and divinylbenzene/ethylbenzene monomers using gamma irradiation. The influence of the solvent solubility parameter, ionic strength, and temperature on swelling and gel density were studied. Adsorption of water vapor on these gels was determined, and the data were used in the calculation of free energy changes involved in the process. Finally the drug release behavior-crosslink content relation was investigated. It was found that increase in crosslinking agent content adversely influenced swelling, gel density, and water vapor adsorption. The solvent solubility parameter was found to influence swelling more than ionic strength. Contrary to what was expected, it was not possible to classify the drug release behavior as first order.

  16. Temporally degradable collagen-mimetic hydrogels tuned to chondrogenesis of human mesenchymal stem cells.

    Science.gov (United States)

    Parmar, Paresh A; Skaalure, Stacey C; Chow, Lesley W; St-Pierre, Jean-Philippe; Stoichevska, Violet; Peng, Yong Y; Werkmeister, Jerome A; Ramshaw, John A M; Stevens, Molly M

    2016-08-01

    Tissue engineering strategies for repairing and regenerating articular cartilage face critical challenges to recapitulate the dynamic and complex biochemical microenvironment of native tissues. One approach to mimic the biochemical complexity of articular cartilage is through the use of recombinant bacterial collagens as they provide a well-defined biological 'blank template' that can be modified to incorporate bioactive and biodegradable peptide sequences within a precisely defined three-dimensional system. We customized the backbone of a Streptococcal collagen-like 2 (Scl2) protein with heparin-binding, integrin-binding, and hyaluronic acid-binding peptide sequences previously shown to modulate chondrogenesis and then cross-linked the recombinant Scl2 protein with a combination of matrix metalloproteinase 7 (MMP7)- and aggrecanase (ADAMTS4)-cleavable peptides at varying ratios to form biodegradable hydrogels with degradation characteristics matching the temporal expression pattern of these enzymes in human mesenchymal stem cells (hMSCs) during chondrogenesis. hMSCs encapsulated within the hydrogels cross-linked with both degradable peptides exhibited enhanced chondrogenic characteristics as demonstrated by gene expression and extracellular matrix deposition compared to the hydrogels cross-linked with a single peptide. Additionally, these combined peptide hydrogels displayed increased MMP7 and ADAMTS4 activities and yet increased compression moduli after 6 weeks, suggesting a positive correlation between the degradation of the hydrogels and the accumulation of matrix by hMSCs undergoing chondrogenesis. Our results suggest that including dual degradation motifs designed to respond to enzymatic activity of hMSCs going through chondrogenic differentiation led to improvements in chondrogenesis. Our hydrogel system demonstrates a bimodal enzymatically degradable biological platform that can mimic native cellular processes in a temporal manner. As such, this novel

  17. Investigation of hydrogel membranes containing a combination of timolol maleate and brimonidine tartrate for ocular delivery

    Directory of Open Access Journals (Sweden)

    Prabhakara Prabhu

    2014-01-01

    Full Text Available Hydrogels are comprised of a cross-linked network of polymers. Water penetrates these networks, resulting in swelling and giving the hydrogel a soft and rubbery consistency, thereby maintaining the integrity of the membrane. Because of the drawback of conventional therapy for ocular delivery, a hydrogel membrane containing a combination of timolol maleate and brimonidine tartrate were formulated for the treatment of glaucoma. In the present investigation, hydrogel membranes were prepared using polymers like gelatin, PVA and chitosan, which were cross-linked using physical and/or chemical methods. The cross-linking of the membranes was confirmed by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD and Differential scanning calorimetry (DSC studies. From the scanning electron microscopy (SEM of the membranes, it appeared homogenous and showed no separation. The pH of the membranes ranged from 7.21-7.4. The hydrogels showed a considerably good swelling ratio ranging from 91.66-372.72%. The drug content ranged from 82.78-95.62%. The in vitro drug release study indicated that there was a slow and sustained release of the drug from the membranes that were sufficiently cross-linked and followed zero order release. The Intraocular pressure (IOP lowering activity of the prepared formulation was compared with the marketed formulation, and it was found that the IOP lowering action was sustained for a long period of time. Stability studies proved that the formulations could be stable when stored at room temperature. Results of the study indicate that it is possible to develop a safe and physiologically effective hydrogel that is patient compliant.

  18. Radiation induced crosslinking of cellulose ethers

    International Nuclear Information System (INIS)

    The effects of high-energy radiation on four ethers of cellulose: carboxymethyl (CMC); hydroxypropyl (HPC), hydroxyethyl (HEC) and methylcellulose (MC) were investigated. Polymers are irradiated in solid state and in aqueous solutions at various concentrations. Degree of substitution (DS) of the derivatives, the concentration of their aqueous solutions and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid state and in diluted aqueous solutions resulted in their degradation. However, it was found that for concentrated solutions gel formation occurred. Paste-like form of the initial material, when water plasticizes the bulk of polymer as well as the high dose rate, what prevents oxygen penetration of the polymer during irradiation, have been found favourable for hydrogel formation. Up to 95% of gel fraction was obtained from solutions of CMC with concentration over 50% irradiated by γ-rays or electron beam. It was pointed out that the ability to the formation of the three-dimensional network is related to the DS of anhydroglucose units and a type of chemical group introduced to main chain of cellulose. Produced hydrogels swelled markedly in water. Despite of the crosslinked structure they underwent degradation by the action of cellulase enzyme or microorganisms from compost, and can be included into the group of biodegradable materials. (author)

  19. Hydrogels contact lenses

    Czech Academy of Sciences Publication Activity Database

    Michálek, Jiří; Hobzová, Radka; Přádný, Martin; Dušková, Miroslava

    New York : Springer, 2010 - (Ottenbrite, R.; Park, K.; Okano, T.), s. 303-315 ISBN 978-1-4419-5918-8 R&D Projects: GA AV ČR KAN200520804 Institutional research plan: CEZ:AV0Z40500505 Keywords : contact lenses * hydrogels * silicone-hydrogels Subject RIV: EI - Biotechnology ; Bionics http://www.springerlink.com/content/l32kx3303v110unn/

  20. Thermal gelation and tissue adhesion of biomimetic hydrogels

    International Nuclear Information System (INIS)

    Marine and freshwater mussels are notorious foulers of natural and manmade surfaces, secreting specialized protein adhesives for rapid and durable attachment to wet substrates. Given the strong and water-resistant nature of mussel adhesive proteins, significant potential exists for mimicking their adhesive characteristics in bioinspired synthetic polymer materials. An important component of these proteins is L-3,4-dihydroxylphenylalanine (DOPA), an amino acid believed to contribute to mussel glue solidification through oxidation and crosslinking reactions. Synthetic polymers containing DOPA residues have previously been shown to crosslink into hydrogels upon the introduction of oxidizing reagents. Here we introduce a strategy for stimuli responsive gel formation of mussel adhesive protein mimetic polymers. Lipid vesicles with a bilayer melting transition of 37 0C were designed from a mixture of dipalmitoyl and dimyristoyl phosphatidylcholines and exploited for the release of a sequestered oxidizing reagent upon heating from ambient to physiologic temperature. Colorimetric studies indicated that sodium-periodate-loaded liposomes released their cargo at the phase transition temperature, and when used in conjunction with a DOPA-functionalized poly(ethylene glycol) polymer gave rise to rapid solidification of a crosslinked polymer hydrogel. The tissue adhesive properties of this biomimetic system were determined by in situ thermal gelation of liposome/polymer hydrogel between two porcine dermal tissue surfaces. Bond strength measurements showed that the bond formed by the adhesive hydrogel (mean = 35.1 kPa, SD = 12.5 kPa, n = 11) was several times stronger than a fibrin glue control tested under the same conditions. The results suggest a possible use of this biomimetic strategy for repair of soft tissues

  1. NIR-Triggered Rapid Shape Memory PAM-GO-Gelatin Hydrogels with High Mechanical Strength.

    Science.gov (United States)

    Huang, Jiahe; Zhao, Lei; Wang, Tao; Sun, Weixiang; Tong, Zhen

    2016-05-18

    Shape memory hydrogels containing over 76 wt % of water were synthesized in a one-pot method, and interpenetrating double network was formed by physically cross-linked gelatin network and chemically cross-linked polyacrylamide (PAM) network with graphene oxide (GO). The temporary shape was quickly fixed by cooling in ice water for 30 s after deformation at 80 °C for 10 s. Shape recovery started in 10 s under near-infrared (NIR) irradiation and almost completed within 60 s depending on the curling angle. A small amount of GO in the hydrogels (≤1.5 mg/mL) played a key role in NIR energy absorption and transformation into thermal energy. The hydrogel without GO showed no response to the NIR irradiation and cannot recover to its permanent shape by NIR irradiation. Temperature sweep was conducted in the cycle of 20 °C → 80 °C → 20 °C, and the structure change in the hydrogels with temperature was investigated according to the storage modulus G' and tangent of the loss angle tan δ as a function of the hydrogel composition. The shape-memory capability was confirmed as the contribution from the triple-helix cross-linking network of gelatin. High mechanical toughness (strength > 400 kPa and broken strain > 500%) was achieved by the double-network with the sacrificial gelatin network and GO bridging to dissipate deformation energy. The optimized composition of the hydrogel was found to be a key point to realize stable temporary shape and rapid recovery to the permanent shape controlled by NIR irradiation with reasonable strength. The facile preparation and noncontact gentle stimulus of the present hydrogel hold great potential to be used in soft actuator materials. PMID:27116394

  2. New antifouling silica hydrogel.

    Science.gov (United States)

    Beltrán-Osuna, Ángela A; Cao, Bin; Cheng, Gang; Jana, Sadhan C; Espe, Matthew P; Lama, Bimala

    2012-06-26

    In this work, a new antifouling silica hydrogel was developed for potential biomedical applications. A zwitterionic polymer, poly(carboxybetaine methacrylate) (pCBMA), was produced via atom-transfer radical polymerization and was appended to the hydrogel network in a two-step acid-base-catalyzed sol-gel process. The pCBMA silica aerogels were obtained by drying the hydrogels under supercritical conditions using CO(2). To understand the effect of pCBMA on the gel structure, pCBMA silica aerogels with different pCBMA contents were characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and the surface area from Brauner-Emmet-Teller (BET) measurements. The antifouling property of pCBMA silica hydrogel to resist protein (fibrinogen) adsorption was measured using enzyme-linked immunosorbent assay (ELISA). SEM images revealed that the particle size and porosity of the silica network decreased at low pCBMA content and increased at above 33 wt % of the polymer. The presence of pCBMA increased the surface area of the material by 91% at a polymer content of 25 wt %. NMR results confirmed that pCBMA was incorporated completely into the silica structure at a polymer content below 20 wt %. A protein adsorption test revealed a reduction in fibrinogen adsorption by 83% at 25 wt % pCBMA content in the hydrogel compared to the fibrinogen adsorption in the unmodified silica hydrogel. PMID:22607091

  3. Biological and mechanical implications of PEGylating proteins into hydrogel biomaterials.

    Science.gov (United States)

    Gonen-Wadmany, Maya; Goldshmid, Revital; Seliktar, Dror

    2011-09-01

    Protein PEGylation has been successfully applied in pharmaceuticals and more recently in biomaterials development for making bioactive and structurally versatile hydrogels. Despite many advantages in this regard, PEGylation of proteins is also known to alter biological activity and modify biophysical characteristics in ways that may be detrimental to cells. The aim of this study was to evaluate the relative loss of biological compatibility associated with PEGylating a fibrinogen precursor into a hydrogel scaffold, in comparison to thrombin cross-linked fibrin hydrogels. Specifically, we investigated the consequences of conjugating fibrinogen with linear polyethtylene glycol (PEG) polymer chains (10 kDa) on the ability to cultivate neonatal human foreskin fibroblasts (HFFs) in 3-D. For this purpose, thrombin cross-linked fibrin (TCL-Fib) and PEGylated fibrinogen (PEG-Fib) gels were prepared with HFFs and cultured for up to seven days. The benchmark biological compatibility test was based on a combined assessment of cellular morphology, proliferation, actin expression, and matrix metalloproteinase (MMP) expression in the 3-D culture systems. The results showed correlations between modulus and proteolytic biodegradation in both materials, but no correlation between the mechanical properties and the ability of HFFs to remodel the microenvironment. A slight reduction of actin, MMPs, and spindled morphology of the cells in the PEG-Fib hydrogels indicated that the PEGylation process altered the biological compatibility of the fibrin. Nevertheless, the overall benchmark performance of the two materials demonstrated that PEGylated fibrinogen hydrogels still retains much to the inherent biofunctionality of the fibrin precursor when used as a scaffold for 3-D cell cultivation. PMID:21669457

  4. Resilin-Like Polypeptide Hydrogels Engineered for Versatile Biological Functions.

    Science.gov (United States)

    Li, Linqing; Tong, Zhixiang; Jia, Xinqiao; Kiick, Kristi L

    2013-01-01

    Natural resilin, the rubber-like protein that exists in specialized compartments of most arthropods, possesses excellent mechanical properties such as low stiffness, high resilience and effective energy storage. Recombinantly-engineered resilin-like polypeptides (RLPs) that possess the favorable attributes of native resilin would be attractive candidates for the modular design of biomaterials for engineering mechanically active tissues. Based on our previous success in creating a novel RLP-based hydrogel and demonstrating useful mechanical and cell-adhesive properties, we have produced a suite of new RLP-based constructs, each equipped with 12 repeats of the putative resilin consensus sequence and a single, distinct biologically active domain. This approach allows independent control over the concentrations of cell-binding, MMP-sensitive, and polysaccharide-sequestration domains in hydrogels comprising mixtures of the various RLPs. The high purity, molecular weight and correct compositions of each new polypeptide have been confirmed via high performance liquid chromatography (HPLC), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and amino acid analysis. These RLP-based polypeptides exhibit largely random-coil conformation, both in solution and in the cross-linked hydrogels, as indicated by circular dichroic and infrared spectroscopic analyses. Hydrogels of various compositions, with a range of elastic moduli (1kPa to 25kPa) can be produced from these polypeptides, and the activity of the cell-binding and matrix metalloproteinase (MMP) sensitive domains was confirmed. Tris(hydroxymethyl phosphine) cross-linked RLP hydrogels were able to maintain their mechanical integrity as well as the viability of encapsulated primary human mesenchymal stem cells (MSCs). These results validate the promising properties of these RLP-based elastomeric biomaterials. PMID:23505396

  5. Calcium-Ion-Triggered Co-assembly of Peptide and Polysaccharide into a Hybrid Hydrogel for Drug Delivery

    OpenAIRE

    Xie, Yanyan; Zhao, Jun; Huang, Renliang; Qi, Wei; Wang, Yuefei; Su, Rongxin; He, Zhimin

    2016-01-01

    We report a new approach to constructing a peptide–polysaccharide hybrid hydrogel via the calcium-ion-triggered co-assembly of fluorenylmethyloxycarbonyl-diphenylalanine (Fmoc-FF) peptide and alginate. Calcium ions triggered the self-assembly of Fmoc-FF peptide into nanofibers with diameter of about 30 nm. Meanwhile, alginate was rapidly crosslinked by the calcium ions, leading to the formation of stable hybrid hydrogel beads. Compared to alginate or Fmoc-FF hydrogel alone, the hybrid Fmoc-FF...

  6. Reduced Graphene Oxide-Based Silver Nanoparticle-Containing Composite Hydrogel as Highly Efficient Dye Catalysts for Wastewater Treatment

    OpenAIRE

    Tifeng Jiao; Haiying Guo; Qingrui Zhang; Qiuming Peng; Yongfu Tang; Xuehai Yan; Bingbing Li

    2015-01-01

    New reduced graphene oxide-based silver nanoparticle-containing composite hydrogels were successfully prepared in situ through the simultaneous reduction of GO and noble metal precursors within the GO gel matrix. The as-formed hydrogels are composed of a network structure of cross-linked nanosheets. The reported method is based on the in situ co-reduction of GO and silver acetate within the hydrogel matrix to form RGO-based composite gel. The stabilization of silver nanoparticles was also ach...

  7. Calcium-Ion-Triggered Co-assembly of Peptide and Polysaccharide into a Hybrid Hydrogel for Drug Delivery.

    Science.gov (United States)

    Xie, Yanyan; Zhao, Jun; Huang, Renliang; Qi, Wei; Wang, Yuefei; Su, Rongxin; He, Zhimin

    2016-12-01

    We report a new approach to constructing a peptide-polysaccharide hybrid hydrogel via the calcium-ion-triggered co-assembly of fluorenylmethyloxycarbonyl-diphenylalanine (Fmoc-FF) peptide and alginate. Calcium ions triggered the self-assembly of Fmoc-FF peptide into nanofibers with diameter of about 30 nm. Meanwhile, alginate was rapidly crosslinked by the calcium ions, leading to the formation of stable hybrid hydrogel beads. Compared to alginate or Fmoc-FF hydrogel alone, the hybrid Fmoc-FF/alginate hydrogel had much better stability in both water and a phosphate-buffered solution (PBS), probably because of the synergistic effect of noncovalent and ionic interactions. Furthermore, docetaxel was chosen as a drug model, and it was encapsulated by hydrogel beads to study the in vitro release behavior. The sustained and controlled docetaxel release was obtained by varying the concentration ratio between Fmoc-FF peptide and alginate. PMID:27067732

  8. 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.

  9. Calcium-Ion-Triggered Co-assembly of Peptide and Polysaccharide into a Hybrid Hydrogel for Drug Delivery

    Science.gov (United States)

    Xie, Yanyan; Zhao, Jun; Huang, Renliang; Qi, Wei; Wang, Yuefei; Su, Rongxin; He, Zhimin

    2016-04-01

    We report a new approach to constructing a peptide-polysaccharide hybrid hydrogel via the calcium-ion-triggered co-assembly of fluorenylmethyloxycarbonyl-diphenylalanine (Fmoc-FF) peptide and alginate. Calcium ions triggered the self-assembly of Fmoc-FF peptide into nanofibers with diameter of about 30 nm. Meanwhile, alginate was rapidly crosslinked by the calcium ions, leading to the formation of stable hybrid hydrogel beads. Compared to alginate or Fmoc-FF hydrogel alone, the hybrid Fmoc-FF/alginate hydrogel had much better stability in both water and a phosphate-buffered solution (PBS), probably because of the synergistic effect of noncovalent and ionic interactions. Furthermore, docetaxel was chosen as a drug model, and it was encapsulated by hydrogel beads to study the in vitro release behavior. The sustained and controlled docetaxel release was obtained by varying the concentration ratio between Fmoc-FF peptide and alginate.

  10. Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

    International Nuclear Information System (INIS)

    Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D2O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10−5 cm2/sec

  11. Bioactive glasses-incorporated, core-shell-structured polypeptide/polysaccharide nanofibrous hydrogels.

    Science.gov (United States)

    Chen, Jian; Chen, Xiaoyi; Yang, Xianyan; Han, Chunmao; Gao, Changyou; Gou, Zhongru

    2013-01-30

    Although the synthetic hydrogel materials capable of accelerating wound healing are being developed at a rapid pace, achieving inorganic-organic hybrid at nanoscale dimension in nanofibrous hydrogels is still a great challenge because of its notorious brittleness and microstructural stability in wet state. Here, we developed a new nanofibrous gelatin/bioactive glass (NF-GEL/BG) composite hydrogel by phase separation method and followed by arming the nanofibers network with counterionic chitosan-hyaluronic acid pairs for improving microstructural and thermal integrity. We achieve this feature by carrying an optimal balance of charges that allows the inorganic ion release in aqueous solution without minimal structure collapse. Therefore, such NF-GEL-based, polysaccharide-crosslinked bioactive hydrogel could afford a close biomimicry to the fibrous nanostructure and constituents of the hierarchically organized natural soft tissues to facilitate chronic, nonhealing wound treatment. PMID:23218343

  12. Astrocytes alignment and reactivity on collagen hydrogels patterned with ECM proteins.

    Science.gov (United States)

    Hsiao, Tony W; Tresco, Patrick A; Hlady, Vladimir

    2015-01-01

    To modulate the surface properties of collagen and subsequent cell-surface interactions, a method was developed to transfer protein patterns from glass coverslips to collagen type I hydrogel surfaces. Two proteins and one proteoglycan found in central nervous system extracellular matrix as well as fibrinogen were patterned in stripes onto collagen hydrogel and astrocytes were cultured on these surfaces. The addition of the stripe protein patterns to hydrogels created astrocyte layers in which cells were aligned with underlying patterns and had reduced chondroitin sulfate expression compared to the cells grown on collagen alone. Protein patterns were covalently cross-linked to the collagen and stable over four days in culture with no visible cellular modifications. The present method can be adapted to transfer other types of protein patterns from glass coverslips to collagen hydrogels. PMID:25477179

  13. Swelling and Drug Release Properties of Starch Based Copolymer Hydrogel Prepared By Ionizing Radiation

    International Nuclear Information System (INIS)

    ph-sensitive hydrogels composed of starch /acrylic acid were prepared by means of gamma-radiation induced graft copolymerization and crosslinking. The effects of the preparation conditions such as the feed solution concentration and composition and irradiation dose on the gelation process of the synthesized copolymer were investigated. The effects of ph and ionic strength on the equilibrium of swelling for the prepared hydrogels were studied. The swelling behavior of the starch/acrylic acid copolymer hydrogels was examined by studying the effect of the hydrogel composition on the time- and ph-dependent swelling. In order to estimate the ability of the prepared copolymer to be used as a colon-specific drug carrier, the release of ketoprofen was monitored as a function of time at ph 1 and ph 7

  14. Characterization of chitosan - poly(vinyl alcohol) hydrogels obtained by gamma radiation

    International Nuclear Information System (INIS)

    We have been obtained chitosan with poly(vinyl alcohol) (PVA) hydrogels using gamma radiation. A preliminary analysis of the type of interaction between the chitosan and PVA chains in these hydrogels are presented. The chitosan in solution quickly decreases its molecular weight as a result of the gamma radiation, whereas the PVA in aqueous solution form hydrogels after being irradiated with 5 kGy or higher. Nevertheless, the mixtures of chitosan and PVA form stable hydrogels in which these polymers are not significantly degraded. We present evidences that suggest the PVA and chitosan chains are covalently crosslinked. This is explained in terms of reactivity of the radicals formed by gamma radiation. (author)

  15. Hydrogel wound dressing preparation at the laboratory scale by using electron beam and gamma radiation

    International Nuclear Information System (INIS)

    The present work describes the preparation of hydrogel based on cross-linked networks of poly (N-vinylpirrolidone), PVP, with polyethyleneglicol and agar with 90% water and PVP nancomposites with a synthetic nanoclay, Laponite XLG, for use as burn dressings. These systems were obtained in two ways: using gamma Co-60 and electron beam radiation. The gelation obtained dose was Dg= 1.72 kGy. The elastic modulus of hydrogel was independent of the method of irradiation. It was 0.39 MPa for the hydrogel irradiated with gamma Co-60 and 0.38 MPa for electron beam irradiation. The elastic modulus of the nanocomposite membrane was 1.25 MPa, three times higher. These results indicate that the PVP/Laponite XLG nanocomposite hydrogel membrane is the best choice for wound dressing applications due to its high water sorption capacity and its superior mechanical properties.

  16. Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Prabhudesai, S. A., E-mail: swapnil@barc.gov.in; Mitra, S.; Mukhopadhyay, R. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 40085 (India); Lawrence, Mathias B. [Department of Physics, St. Xavier’s College, Mapusa, Goa 403507 (India); Desa, J. A. E. [Department of Physics, Goa University, Taleigao Plateau, Goa 403206 (India)

    2015-06-24

    Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D{sub 2}O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10{sup −5} cm{sup 2}/sec.

  17. Laterally Sandwich-typed Hydrogel Columns with Liner Poly(N-isopropylacrylamide)Layer: Preparation, Swelling/ deswelling Kinetics and Drug Delivery Characteristics

    Institute of Scientific and Technical Information of China (English)

    LI Ying; XIAO Xincai

    2012-01-01

    A novel thermo-responsive hydrogel column,featured with both ends of linear poly(Nisopropylacrylamide) (PNIPAM) chains being grafted onto cross-linked PNIPAM chains,was reported.The laterally sandwich-typed hydrogel columns were fabricated by radical polymerization in a three-step process using a method of ice-melting synthesis.The initiating path,morphology and thermoresponsive characteristics of the prepared hydrogel columns were experimentally studied.The results show that the hydrogel column obtained by the initiator inside part has more quick swelling and deswelling rates responsing to temperature cycling than other hydrogels owing to linear PNIPAM chains to form supermacroporous structure.The proposed hydrogel structure provide a new mode of the phase transition behavior for thermo-sensitive "smart" or "intelligent" monodisperse micro-actuators,which is highly attractive for targeting drug delivery systems,chemical separations,and sensors and so on.

  18. Radiolytic formation of Ag clusters in aqueous polyvinyl alcohol solution and hydrogel matrix

    International Nuclear Information System (INIS)

    Ag+ ions, in aqueous polyvinyl alcohol (PVA) solution and in PVA hydrogel matrix have been gamma radiolytically reduced to produce Ag clusters. UV-visible absorption spectral characteristics of Ag clusters obtained under different gamma dose, Ag+ concentration, PVA concentration and crosslinking density of the gel used have been studied. The effect of Ag+ ions on the radiation crosslinking of the PVA chains, have also been investigated by viscosity measurements. The radiation-induced Ag+ ion reduction was followed by crosslinking of the PVA chains. PVA was found to be a very efficient stabilizer to prevent aggregation of Ag clusters. The clusters produced in the hydrogel matrix were expected to be smaller than the pore size (∼2-20 nm) of the gels used in the study. These Ag clusters were unable to reduce methyl viologen (MV2+) chloride and were stable in air

  19. Thiol-ene Photocrosslinking of Cytocompatible Resilin-Like Polypeptide-PEG Hydrogels.

    Science.gov (United States)

    McGann, Christopher L; Dumm, Rebekah E; Jurusik, Anna K; Sidhu, Ishnoor; Kiick, Kristi L

    2016-01-01

    A range of chemical strategies have been used for crosslinking recombinant polypeptide hydrogels, although only a few have employed photocrosslinking approaches. Here, we capitalize on the novel insect protein, resilin, and the versatility of click reactions to introduce a resilin-like polypeptide (RLP) that is capable of photoinitiated thiol-ene crosslinking. Lysine residues of the RLP were functionalized with norbornene acid as confirmed via 1H-NMR spectroscopy. The RLPNs were subsequently photocrosslinked with multi-arm PEG thiols in the presence of a photoinitiator to form elastic hybrid hydrogels. The crosslinking reaction and resulting RLP-PEG networks demonstrated cytocompatibility with human mesenchymal stem cells in both 2D cell-adhesion and 3D photoencapsulation studies. PMID:26435299

  20. Controlled release of acetylsalicylic acid from polythiophene/carrageenan hydrogel via electrical stimulation.

    Science.gov (United States)

    Pairatwachapun, Sanita; Paradee, Nophawan; Sirivat, Anuvat

    2016-02-10

    Blends between polythiophene (PTh) and a carrageenan hydrogel were fabricated as the matrix for the electric field assisted drug release. The pristine carrageenan and the blend films were prepared by the solution casting using acetylsalicylic acid (ASA) as the anionic model drug and Mg(2+), Ca(2+), and Ba(2+) as the crosslinking agents. The ASA was released by the Fickian diffusion mechanism. The diffusion coefficient decreased with increasing crosslinking ratio or decreasing crosslinking ionic radii. The diffusion coefficients were greater with the applied electrical potentials by an order of magnitude relative to those without electric field. Moreover, the diffusion coefficients with PTh as the drug carrier were higher than those without PTh. Thus, the presence of the conductive polymer in the hydrogel blend coupled with applied electric field is shown here to drastically enhance the drug delivery rate. PMID:26686123

  1. Novel cross linked guar gum-g-poly(acrylate) porous superabsorbent hydrogels: Characterization and swelling behaviour in different environments.

    Science.gov (United States)

    Chandrika, Ksv Poorna; Singh, Anupama; Rathore, Abhishek; Kumar, Anil

    2016-09-20

    A new series of eco-friendly cross linked guar gum-g-poly(acrylate) porous superabsorbent hydrogels was prepared by in situ grafting polymerization and cross-linking on to a natural guar gum employing N,N-methylene bis acrylamide as cross linker. Morphological and structural characterization of the prepared hydrogels (SPHs) done by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and solid state C(13) NMR spectroscopy confirmed formation of porous grafted and crosslinked hydrogel structure. Increase in cross linker concentration in the feed mass exhibited decrease in porosity and increase in density of the hydrogels. Swelling of an optimized hydrogel (SPH) in response to external stimuli namely, salt solutions, fertilizer solutions, temperature, and pH exhibited high swelling ratios in various environments. Swelling rate of the SPH was faster than the corresponding nonporous superabsorbent hydrogel. The prepared hydrogels can serve as excellent carriers of pesticides, fertilizers and agriculturally important microbes. Biocontrol formulations based on a representative SPH exhibited excellent shelf-life characteristics and bioefficacy against phytopathogenic fungus Pythium aphanidermatum. PMID:27261742

  2. Study on the Depth-Penetration of 350 keV Electron Beam into Hydrogel Wound Dressing

    International Nuclear Information System (INIS)

    Depth-penetration calculation of 350 keV electron beams into hydrogel material is presented in this paper. The determination is based on theory and experiment. These data will be used as a reference in calculating of depth-penetration of electron beams into hydrogel materials. Hydrogel is formed during interaction between electron beams and polymer materials through cross-linking process. In the future, hydrogel will be used as a wound dressing. Polymer materials used in this experiment were PVA, PVP and mixed of both. These materials were chosen, because they tend to cross-link and form hydrogel during interaction with electron beams. The formation of hydrogel is a basic experiment in fabrication of hydrogel wound dressing using electron beam machine. Experimentally, the 350 keV electron beams can be used to irradiate the mixture of PVA and PVP. It’s found that the depth-penetration of 350 keV electron beams into the polymers is 0.204 mm for single-sided treatment and 0.490 mm for double-sided treatment. (author)

  3. Poly(vinyl alcohol)-Poly(ethylene glycol) Double-Network Hydrogel: A General Approach to Shape Memory and Self-Healing Functionalities.

    Science.gov (United States)

    Li, Guo; Zhang, Hongji; Fortin, Daniel; Xia, Hesheng; Zhao, Yue

    2015-10-27

    A double-network polymer hydrogel composed of chemically cross-linked poly(ethylene glycol) (PEG) and physically cross-linked poly(vinyl alcohol) (PVA) was prepared. When the hydrogel (70 wt % of water) is subjected to freezing/thawing treatment under strain, the enhanced physical network as a result of crystallization of PVA chains can stabilize the hydrogel deformation after removal of the external force at room temperature. Subsequent disruption of the physical network of PVA by heating allows for the recovery of the initial shape of the hydrogel. Moreover, the double-network hydrogel exhibits self-healing capability stemming from the physical network of PVA by virtue of the extensive interchain hydrogen bonding between the hydroxyl side groups. This study thus demonstrates a general approach to imparting both the shape memory and self-healing properties to chemically cross-linked hydrogels that otherwise do not have such functionalities. Moreover, by making use of the fixed hydrogel elongation, the effect of anisotropy arising from chain orientation on the self-healing was also observed. PMID:26442631

  4. Template-synthesized opal hydrogels

    Institute of Scientific and Technical Information of China (English)

    LI Jun; JI Lijun; RONG Jianhua; YANG Zhenzhong

    2003-01-01

    Opal hydrogels could be synthesized with polymer inverse opal template. A pH responsive opal N-iso- propylacrylamide/acrylic acid copolymerized hydrogel was prepared as an example. The ordered structure and response to pH were investigated. Through the sol-gel process of tetrabutyl titanate, opal titania was obtained with the opal hydrogel template.

  5. Radiation Synthesis and Application of Carboxymethylated Chitosan Hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Young Chang

    2007-08-15

    This research proposal is to investigate radiation effect of carboxymethylated chitosan in order to obtain the crosslinked carboxymethylated chitosan. The application studies on CM-chitosan- based intelligent hydrogels will be tried too. Chitin is the most abundant natural amino polysaccharide and estimated to be produced annually almost as much as cellulose. Chitosan is the deacetylated product of chitin showing the enhanced solubility in dilute acids, further, carboxymethylated chitosan (CM-chitosan) can solve in both acidic and basic physiological media, which might be good candidates as a kind of biomedical materials. Radiation technique is an important method for modification of chitin derivatives. It includes radiation-induced degradation, grafting, and crosslinking. It was found that CM-chitosan degraded in solid state or dilute aqueous solution under irradiation, but crosslinked at paste-like sate when the concentration of CM-chitosan is more than 10%. Both degraded and crosslinked CM-chitosan have antibacterial activity, so it is essential to investigate in detail the radiation effect of CM-chitosan. Study on radiation effect of CM-chitosan in different condition is beneficial to modification of CM-chitosan by irradiation technique. However, little study was reported on radiation crosslinking and application of CM-chitosan. The radiation-closslinked CM-chitosan synthesized from chitosan was characterized by a Fourier transform infrared spectroscopy (FT-IR) analysis. A kinetic swelling in water and the mechanical properties such as a gelation, water absorptivity, and gel strength were also investigated. For the preparation of crosslinked CM-chitosan by using gamma irradiation, the concentration of an aqueous CM-chitosan is above 10wt%. We confirmed that the gel contents was in the range of 15-63%, and when the irradiation dose was increased, the degree of gelation was decreased by disintegration of the CM-chitosan. In conclusion, we developed a new

  6. Prevention of surgical adhesions using barriers of carboxymethyl cellulose and polyethylene glycol hydrogels synthesized by irradiation

    International Nuclear Information System (INIS)

    Biocompatible and biodegradable hydrogels based on carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) were prepared for physical barriers for preventing surgical adhesions. These interpolymeric hydrogels were synthesized by a gamma irradiation crosslinking technique. The 1.5cm x 1.5cm of cecal serosa and adjacent abdominal wall were abraded with bone burr until the serosal surface was disrupted and hemorrhagic but not perforated, and the serosa of the cecum was sutured to the abdominal wall in 5 mm apart from the injured site. The denuded cecum was covered with either CMC/PEG hydrogels or solution from CMC/PEG hydrogel. Control rat serosa was not covered. Two weeks later, the rats were sacrificed and adhesion was scored on a 0-5 scale. No treatment showed the significantly higher incidence of adhesions than either CMC/PEG hydrogels or solution from CMC/PEG hydrogel. In conclusion, these studies demonstrate that CMC/PEG hydrogels have a function of prevention of intra abdominal adhesion in a rat model. (author)

  7. Hybrid polymeric hydrogels via peptide nucleic acid (PNA)/DNA complexation.

    Science.gov (United States)

    Chu, Te-Wei; Feng, Jiayue; Yang, Jiyuan; Kopeček, Jindřich

    2015-12-28

    This work presents a new concept in hybrid hydrogel design. Synthetic water-soluble N-(2-hydroxypropyl)methacrylamide (HPMA) polymers grafted with multiple peptide nucleic acids (PNAs) are crosslinked upon addition of the linker DNA. The self-assembly is mediated by the PNA-DNA complexation, which results in the formation of hydrophilic polymer networks. We show that the hydrogels can be produced through two different types of complexations. Type I hydrogel is formed via the PNA/DNA double-helix hybridization. Type II hydrogel utilizes a unique "P-form" oligonucleotide triple-helix that comprises two PNA sequences and one DNA. Microrheology studies confirm the respective gelation processes and disclose a higher critical gelation concentration for the type I gel when compared to the type II design. Scanning electron microscopy reveals the interconnected microporous structure of both types of hydrogels. Type I double-helix hydrogel exhibits larger pore sizes than type II triple-helix gel. The latter apparently contains denser structure and displays greater elasticity as well. The designed hybrid hydrogels have potential as novel biomaterials for pharmaceutical and biomedical applications. PMID:26394062

  8. Characterization of hybrid hydrogel with different shape of particles after gamma-ray radiation

    Science.gov (United States)

    Kim, Donghyun; Lee, Hoik; Park, Hyemi; Sohn, Daewon

    2011-03-01

    Due to high specific surface area and the ability to absorb organic molecules, inorganic particles such as silica particle (spherical), imogolite (rodlike), and clay (fan shape) could be used as precursors for hydrogels. The hydrogel which had 3-D network structure was directly prepared by polymerization with acrylic acid (AA) on hydroxide surface of inorganic particles that was irradiated by gamma-ray at ambient condition. Surface of inorganic particles was used as sites of initiator and cross-linker to make hydrogel, so we don't need any additional additives to make hydrogel. The properties of hydrogel were characterized by small angle x-ray scattering (SAXS), universal testing machine (UTM), and Raman spectroscopy. By changing the inorganic particles/monomer ratio, the mechanical strength was significantly changed. The synthesized hydrogel can be elongated maximum 1800%. 2D SAXS pattern was different depending on the shape of inorganic particles. And the hydrogel swelled only in basic solutions at pH > 7.

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

    Science.gov (United States)

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

    2016-01-01

    In this study, O-carboxymethyl chitosan (O-CMCS) was synthesized from chitosan and monochloroacetic acid. Then O-CMCS hydrogel was prepared by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) in which the lincomycin was packaged. The Fourier transform infrared spectrum and scanning electron microscopy were adopted to characterize the structure and morphology of the product. The influences of dosage of EDC/NHS and concentration of O-CMCS on the swelling properties of the hydrogels were investigated. The hydrogels performed good swelling capacities and obvious pH-sensitive properties. The antibacterial activities of the hydrogels were tested against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Compared with pure O-CMCS hydrogels, the antibacterial activities of O-CMCS/lincomycin hydrogels were significantly improved with the increase in the concentration of lincomycin against E. coli and S. aureus. With the increase in dosage of crosslinking agent or concentration of O-CMCS, the antibacterial activities both decreased gradually against the two bacteria. O-CMCS/lincomycin hydrogel was expected to be used for antibacterial material in view of its significant antibacterial activities. PMID:26675323

  10. A drug delivery hydrogel system based on activin B for Parkinson's disease.

    Science.gov (United States)

    Li, Juan; Darabi, Mohammadali; Gu, Jingjing; Shi, Junbin; Xue, Jinhua; Huang, Lu; Liu, Yutong; Zhang, Lei; Liu, N; Zhong, Wen; Zhang, Lin; Xing, Malcolm; Zhang, Lu

    2016-09-01

    Parkinson's disease (PD) is one of the most common neurodegenerative diseases. Activins are members of the superfamily of transforming growth factors and have many potential neuroprotective effects. Herein, at the first place, we verified activin B's neuroprotective role in a PD model, and revealed that activin B's fast release has limited function in the PD therapy. To this end, we developed a multi-functional crosslinker based thermosensitive injectable hydrogels to deliver activin B, and stereotactically injected the activin B-loaded hydrogel into the striatum of a mouse model of PD. The histological evaluation showed that activin B can be detected even 5 weeks post-surgery in PD mice implanted with activin B-loaded hydrogels, and activin B-loaded hydrogels can significantly increase the density of tyrosine hydroxylase positive (TH(+)) nerve fibers and reduce inflammatory responses. The behavioral evaluation demonstrated that activin B-loaded hydrogels significantly improved the performance of the mice in the PD model. Meanwhile, we found that hydrogels can slightly induce the activation of microglia cells and astrocytes, while cannot induce apoptosis in the striatum. Overall, our data demonstrated that the developed activin B-loaded hydrogels provide sustained release of activin B for over 5 weeks and contribute to substantial cellular protection and behavioral improvement, suggesting their potential as a therapeutic strategy for PD. PMID:27322960

  11. Synthesis and characterization of acrylamide-acrylic acid hydrogels and adsorption of some textile dyes

    International Nuclear Information System (INIS)

    Acrylamide (AAm)-acrylic acid (AAc) hydrogels have been prepared at AAm initial compositions of 15%, 20% and 30%. AAm-AAc monomer mixtures have been irradiated in a 60Co-γ source at different doses and percent conversions have been determined gravimetrically. 100% conversion of monomers into hydrogels was achieved at 8 kGy dose. These hydrogels were swollen in distilled water at pH 3.03, 4.18, 4.68, 5.05, 5.30, 6.0, 7.0, 8.0. The results of swelling tests at pH 8.0 indicated that poly(AAm-AAc) hydrogels prepared from solution containing 15% (mol%) AAm showed maximum % swelling as 3000%. Poly(AAm-AAc) hydrogels have been considered for the removal of some textile dyes from aqueous solutions. Among the two common textile dyes tested, Janus Green B (JGB) has showed the highest adsorption capacity while Congo Red (CR) was not adsorbed by these hydrogels. Adsorption isotherms were constructed for JGB and poly(AAm/AAc) gel systems. It is concluded that cross-linked poly(AAm/AAc) hydrogels can be successfully used in the purification of waste water containing certain textile dyes

  12. Preparation of collagen/hydroxyapatite/alendronate hybrid hydrogels as potential scaffolds for bone regeneration.

    Science.gov (United States)

    Ma, Xin; He, Zhiwei; Han, Fengxuan; Zhong, Zhiyuan; Chen, Liang; Li, Bin

    2016-07-01

    Development of biomimetic scaffolds represents a promising direction in bone tissue engineering. In this study, we designed a two-step process to prepare a type of biomimetic hybrid hydrogels that were composed of collagen, hydroxyapatite (HAP) and alendronate (ALN), an anti-osteoporosis drug. First, water-soluble ALN-conjugated HAP (HAP-ALN) containing 4.0wt.% of ALN was synthesized by treating HAP particles with ALN. Hydrogels were then formed from HAP-ALN conjugate and collagen under physiological conditions using genipin (GNP) as the crosslinker. Depending on the ALN/collagen molar ratio and GNP concentration, the gelation time of hydrogels ranged from 5 to 37min. Notably, these hybrid hydrogels exhibited markedly improved mechanical property (storage modulus G'=38-187kPa), higher gel contents, and lower swelling ratios compared to the hydrogels prepared from collagen alone under similar conditions. Moreover, they showed tunable degradation behaviors against collagenase. The collagen/HAP-ALN hybrid hydrogels supported the adhesion and growth of murine MC3T3-E1 osteoblastic cells well. Such tough yet enzymatically degradable hybrid hydrogels hold potential as scaffolds for bone tissue engineering. PMID:26998869

  13. Study of crosslinking induced by gamma radiation in mixtures of polyacrylamide anionic and water

    International Nuclear Information System (INIS)

    Superabsorbent hydrogels are composed of three-dimensional polymeric networks that can absorb and retain body of water hundreds of times the weight of its dry weight. The hydrogels can be crosslinked by chemical or physical. In general, chemical crosslinking is performed in the presence of reactive substances of high toxicity at elevated temperatures, may cause harmful secondary reactions to final product quality. However, ionizing radiation provides the crosslinking in the absence of chemical initiators or crosslinkers, therefore without contamination or toxicity. It also allows the realization of the reaction at low temperatures. These materials find use in several application fields, such as sanitary pads, diapers, controlled release of nutrients to the soil, separation processes, water purification systems and controlled release of drugs. The purpose of this study was to assess the influence of gamma radiation in doses of 15 and 25 kGy, in reticulation system of polyacrylamide (PAAm) and water, which were characterized by swelling and Fourier Transform Infrared Spectroscopy (FTIR). The results show the importance of the amount of water in the reticulation. It was concluded that gamma radiation has excellent potential for the synthesis of hiperabsorbent hydrogels. (author)

  14. MMP-sensitive PEG diacrylate hydrogels with spatial variations in matrix properties stimulate directional vascular sprout formation.

    Directory of Open Access Journals (Sweden)

    Michael V Turturro

    Full Text Available The spatial presentation of immobilized extracellular matrix (ECM cues and matrix mechanical properties play an important role in directed and guided cell behavior and neovascularization. The goal of this work was to explore whether gradients of elastic modulus, immobilized matrix metalloproteinase (MMP-sensitivity, and YRGDS cell adhesion ligands are capable of directing 3D vascular sprout formation in tissue engineered scaffolds. PEGDA hydrogels were engineered with mechanical and biofunctional gradients using perfusion-based frontal photopolymerization (PBFP. Bulk photopolymerized hydrogels with uniform mechanical properties, degradation, and immobilized biofunctionality served as controls. Gradient hydrogels exhibited an 80.4% decrease in elastic modulus and a 56.2% decrease in immobilized YRGDS. PBFP hydrogels also demonstrated gradients in hydrogel degradation with degradation times ranging from 10-12 hours in the more crosslinked regions to 4-6 hours in less crosslinked regions. An in vitro model of neovascularization, composed of co-culture aggregates of endothelial and smooth muscle cells, was used to evaluate the effect of these gradients on vascular sprout formation. Aggregate invasion in gradient hydrogels occurred bi-directionally with sprout alignment observed in the direction parallel to the gradient while control hydrogels with homogeneous properties resulted in uniform invasion. In PBFP gradient hydrogels, aggregate sprout length was found to be twice as long in the direction parallel to the gradient as compared to the perpendicular direction after three weeks in culture. This directionality was found to be more prominent in gradient regions of increased stiffness, crosslinked MMP-sensitive peptide presentation, and immobilized YRGDS concentration.

  15. Exploring elasticity and energy dissipation in mussel-inspired hydrogel transient networks

    Science.gov (United States)

    Grindy, Scott; Learsch, Robert; Holten-Andersen, Niels

    Dynamic, reversible crosslinks have been shown to specifically control the mechanical properties of a wide variety of mechanically tough and resilient biomaterials. We have shown that reversible histidine-metal ion interactions, known to contribute to the strong mechanical properties and self-healing nature of mussel byssal threads, can be used to control and engineer the temporally-hierarchical mechanical properties of model hydrogels orthogonally from the spatial structure of the material. Here, we explore the scaling relationships in our model networks to further inform our abilities to control the relative elasticity and energy dissipation on hierarchical timescales. Scaling arguments suggest that the elasticity is dominated by long-range entanglements, while the dissipation is controlled by the exchange kinetics of the transient crosslinks. Further, we show that by using UV light, we can further control the viscoelastic properties of our mussel-inspired hydrogels in situ. This process opens the door for creating biocompatible hydrogel materials with arbitrary spatial control over their viscoelastic mechanical properties. Overall, we show that by understanding the interplay between bio-inspired dynamic crosslinks and soft matter physics allows us to rationally design high-strength hydrogels for specific states of dynamic loading.

  16. Injectable biopolymer based hydrogels for drug delivery applications.

    Science.gov (United States)

    Atta, Sadia; Khaliq, Shaista; Islam, Atif; Javeria, Irtaza; Jamil, Tahir; Athar, Muhammad Makshoof; Shafiq, Muhammad Imtiaz; Ghaffar, Abdul

    2015-09-01

    Biopolymer based pH-sensitive hydrogels were prepared using chitosan (CS) with polyethylene glycol (PEG) of different molecular weights in the presence of silane crosslinker. The incorporated components remain undissolved in different swelling media as they are connected by siloxane linkage which was confirmed by Fourier transform infrared spectroscopy. The swelling in water was enhanced by the addition of higher molecular weight PEG. The swelling behaviour of the hydrogels against pH showed high swelling in acidic and basic pH, whereas, low swelling was examined at pH 6 and 7. This characteristic pH responsive behaviour at neutral pH made them suitable for injectable controlled drug delivery. The controlled release analysis of Cefixime (CFX) (model drug) loaded CS/PEG hydrogel exhibited that the entire drug was released in 30 min in simulated gastric fluid (SGF) while in simulated intestinal fluid (SIF), 85% of drug was released in controlled manner within 80 min. This inferred that the developed hydrogels can be an attractive biomaterial for injectable drug delivery with physiological pH and other biomedical applications. PMID:26118484

  17. Bioresponsive systems based on polygalacturonate containing hydrogels.

    Science.gov (United States)

    Schneider, Konstantin P; Rollett, Alexandra; Wehrschuetz-Sigl, Eva; Hasmann, Andrea; Zankel, Armin; Muehlebach, Andreas; Kaufmann, Franz; Guebitz, Georg M

    2011-04-01

    Polysaccharide acid (PSA) based devices (consisting of alginic acid and polygalacturonic acid) were investigated for the detection of contaminating microorganisms. PSA-CaCl(2) hydrogel systems were compared to systems involving covalent cross-linking of PSA with glycidylmethacrylate (PSA-GMA) which was confirmed with Fourier Transformed Infrared (FTIR) analysis. Incubation of PSA-CaCl(2) and PSA-GMA beads loaded with Alizarin as a model ingredient with trigger enzymes (polygalacturonases or pectate lyases) or bacteria lead to a smoothening of the surface and exposure of Alizarin according to Environmental Scanning Electron Microscopy (ESEM) analysis. Enzyme triggered release of Alizarin was demonstrated for a commercial enzyme preparation from Aspergillus niger and with purified polygalacturonase and pectate lyase from S. rolfsii and B. pumilus, respectively. In contrast to the PSA-CaCl(2) beads, cross-linking (PSA-GMA beads) restricted the release of Alizarin in absence of enzymes. There was a linear relation between release of Alizarin (5-348 μM) and enzyme activity in a range of 0-300 U ml(-1) dosed. In addition to enzymes, both PSA-CaCl(2) and PSA-GMA beads were incubated with Bacillus subtilis and Yersinia entercolitica as model contaminating microorganism. After 72 h, a release between 10 μM and 57 μM Alizarin was detected. For protection of the hydrogels, an enzymatically modified PET membrane was covalently attached onto the surface. This lead to a slower release and improve long term storage stability based on less than 1% release of dye after 21 days. Additionally, this allowed simple detection by visual inspection of the device due to a colour change of the white membrane to orange upon enzyme triggered release of the dye. PMID:22112943

  18. Controlled release of insulin through hydrogels of (acrylic acid)/trimethylolpropane triacrylate

    Science.gov (United States)

    Raymundi, Vanessa C.; Aguiar, Leandro G.; Souza, Esmar F.; Sato, Ana C.; Giudici, Reinaldo

    2015-12-01

    Hydrogels of poly(acrylic acid) crosslinked with trimethylolpropane triacrylate (TMPTA) were produced through solution polymerization. After these hydrogels were loaded with insulin solution, they evidenced swelling. Experiments of controlled release of insulin through the hydrogels were performed in acidic and basic media in order to evaluate the rates of release of this protein provided by the referred copolymer. Additionally, a mathematical description of the system based on differential mass balance was made and simulated in MATLAB. The model consists of a system of differential equations which was solved numerically. As expected, the values of swelling index at the equilibrium and the rates of insulin release were inversely proportional to the degree of crosslinking. The mathematical model provided reliable predictions of release profiles with fitted values of diffusivity of insulin through the hydrogels in the range of 6.0 × 10-7-1.3 × 10-6 cm2/s. The fitted and experimental values of partition coefficients of insulin between the hydrogel and the medium were lower for basic media, pointing out good affinity of insulin for these media in comparison to the acidic solutions.

  19. Synthesis of PVA/PVP hydrogels having two layers by radiation and their physical properties

    International Nuclear Information System (INIS)

    Complete text of publication follows. The radiation can induce chemical reaction to modify polymer under even the solid state or in the low temperature. The radiation crosslinking can be easily adjusted by controlling the radiation dose and is reproducible. The finished product contains no residuals of substances required to initiate the chemical crosslinking that can restrict the application possibilities. In these studies, two layer's hydrogel which consisted of urethane membrane and a mixture of polyvinyl alcohol/poly-N-vinylpyrrolidone /glycerin/chitosan was made by gamma-ray irradiation or two steps of 'freezing and thawing' and gamma-ray irradiation for wound dressing. The physical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the hydrogels for wound dressing. Urethane was dissolved in solvent, the urethane solution was poured on the mould, and then dried to make the thin membrane. Hydrophilic polymer solutions were poured on the urethane membranes, they were exposed to gamma irradiation or 'freezing and thawing' and gamma irradiation doses of 25, 35, 50 and 60 kGy to evaluate the physical properties of hydrogels. The physical properties of hydrogels such as gelation and gel strength were improved, and the evaporation speed of water in hydrogel was low when urethane membrane was used

  20. Swelling behaviors,tensile properties and thermodynamic interactions in APS/HEMA copolymeric hydrogels

    Institute of Scientific and Technical Information of China (English)

    LIN Zhihui; WU Wenhui; WANG Jianquan; JIN Xin

    2007-01-01

    A series of hydrogels was synthesized from hydrophobic allyl phenyl sulfone (APS) and hydrophilic 2-hydroxyethyl methacrylate (HEMA) by bulk flee radical copolymerization.The effects of APS content and temperature were studied on network parameters such as efiective crosslink density(ve),molar mass between crosslinks(Mc) and polymer-water interaction parameter (χ) of hydrogels.The increase in APS content was shown to enhance hydrophobic bonding within hydrogel.1eading to the decrease in equilibrium water content(EWC)and the increase in volume fraction of polymer in hydrogel(φ2),tensile strength and Young'S modulus.At the same time,the increases in (Ve) and φ and the decrease in Mc were also observed.When the temperature is increased from 273 to 343 K,the hydrogel A/H3 undergoes decreasing in EWC and increasing in φ2 and χ values.The thermodynamic analysis indicated that the swelling process is an exothermic process.

  1. An Injectable Hydrogel as Bone Graft Material with Added Antimicrobial Properties.

    Science.gov (United States)

    Tommasi, Giacomo; Perni, Stefano; Prokopovich, Polina

    2016-06-01

    Currently, the technique which provides the best chances for a successful bone graft, is the use of bone tissue from the same patient receiving it (autograft); the main limitations are the limited availability and the risks involved in removing living bone tissue, for example, explant site pain and morbidity. Allografts and xenografts may overcome these limitations; however, they increase the risk of rejection. For all these reasons the development of an artificial bone graft material is particularly important and hydrogels are a promising alternative for bone regeneration. Gels were prepared using 1,4-butanediol diacrylate as crosslinker and alpha tricalciumphosphate; ZnCl2 and SrCl2 were added to the aqueous phase. MTT results demonstrated that the addition of strontium had a beneficial effect on the osteoblast cells density on hydrogels, and zinc instead did not increase osteoblast proliferation. The amount of calcium produced by the osteoblast cells quantified through the Alizarin Red protocol revealed that both strontium and zinc positively influenced the formation of calcium; furthermore, their effect was synergistic. Rheology properties were used to mechanically characterize the hydrogels and especially the influence of crosslinker's concentration on them, showing the hydrogels presented had extremely good mechanical properties. Furthermore, the antimicrobial activity of strontium and zinc in the hydrogels against methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis was determined. PMID:27174392

  2. 3D Cell Culture in Alginate Hydrogels

    Directory of Open Access Journals (Sweden)

    Therese Andersen

    2015-03-01

    Full Text Available This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent, and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell–matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue.

  3. Nanoparticle diffusometry in hydrogels

    OpenAIRE

    Kort, de, YAW Yvonne

    2016-01-01

    In order to understand food product functionality such as elastic and flow behavior and mass transport properties, one first has to understand the multi-length-scale structure of the material. The aim of this work is to explore novel methodologies to study and characterize multi-length-scale structures of food hydrogels under static and dynamic conditions. The focus lies on hydrogels comprising polysaccharides, because they show a rich variation in elastic and flow behavior. The largest part of ...

  4. 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.

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

  7. Exploring natural silk protein sericin for regenerative medicine: an injectable, photoluminescent, cell-adhesive 3D hydrogel

    Science.gov (United States)

    Wang, Zheng; Zhang, Yeshun; Zhang, Jinxiang; Huang, Lei; Liu, Jia; Li, Yongkui; Zhang, Guozheng; Kundu, Subhas C.; Wang, Lin

    2014-11-01

    Sericin, a major component of silk, has a long history of being discarded as a waste during silk processing. The value of sericin for tissue engineering is underestimated and its potential application in regenerative medicine has just begun to be explored. Here we report the successful fabrication and characterization of a covalently-crosslinked 3D pure sericin hydrogel for delivery of cells and drugs. This hydrogel is injectable, permitting its implantation through minimally invasive approaches. Notably, this hydrogel is found to exhibit photoluminescence, enabling bioimaging and in vivo tracking. Moreover, this hydrogel system possesses excellent cell-adhesive capability, effectively promoting cell attachment, proliferation and long-term survival of various types of cells. Further, the sericin hydrogel releases bioactive reagents in a sustained manner. Additionally, this hydrogel demonstrates good elasticity, high porosity, and pH-dependent degradation dynamics, which are advantageous for this sericin hydrogel to serve as a delivery vehicle for cells and therapeutic drugs. With all these unique features, it is expected that this sericin hydrogel will have wide utility in the areas of tissue engineering and regenerative medicine.

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

    Science.gov (United States)

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

    2010-10-01

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

  9. New cellulose–lignin hydrogels and their application in controlled release of polyphenols

    International Nuclear Information System (INIS)

    Novel superabsorbant cellulose–lignin hydrogels (CL) were prepared by a new two-step procedure consisting in dissolving cellulose in an alkaline solution with further mixing with lignin, followed by the chemical crosslinking with epichlorohydrin. The crosslinking occurrence was verified by Fourier Transform Infrared spectroscopy (FT-IR). The effect of the structure features of cellulose–lignin hydrogels on their dehydration heat was evaluated by Differential Scanning Calorimetry (DSC). The Scanning Electron Microscopy (SEM) images reveal some morphological aspects of the hydrogels. The degree as well as the rate of swelling in a mixture of water:ethanol = 19:1 were estimated. The possible application of these hydrogels as controlled release systems was tested. Polyphenols known as having a wide range of biological effects were selected to be incorporated in such hydrogels by an optimal procedure. The extract of grapes seeds from the Chambourcin type was used as a source of polyphenols (PF). The amount of the incorporated polyphenols was estimated by UV–VIS measurements. Characterization of the hydrogels containing polyphenols was performed by FTIR spectroscopy. Some parameters were estimated based on the registered spectra, as H-bond energy (EH), the asymmetric index (a/b) and the enthalpy of H-bond formation (ΔH). The modifications of the thermal behavior and morphology induced by the presence of the polyphenols in hydrogels were highlighted by DSC and SEM, respectively. The release of polyphenols from CL hydrogels depended on the lignin content from matrices, as assessed by spectral studies. Both loading with polyphenols and their release can be controlled by the composition of the hydrogels. The kinetic of polyphenols release was studied. - Highlights: ► A unique method to obtain cellulose–lignin hydrogels. ► The application of these hydrogels as controlled release systems was tested. ► Polyphenols from grapes seed as active ingredient.

  10. New cellulose-lignin hydrogels and their application in controlled release of polyphenols

    Energy Technology Data Exchange (ETDEWEB)

    Ciolacu, Diana, E-mail: dciolacu@icmpp.ro; Oprea, Ana Maria; Anghel, Narcis; Cazacu, Georgeta; Cazacu, Maria

    2012-04-01

    Novel superabsorbant cellulose-lignin hydrogels (CL) were prepared by a new two-step procedure consisting in dissolving cellulose in an alkaline solution with further mixing with lignin, followed by the chemical crosslinking with epichlorohydrin. The crosslinking occurrence was verified by Fourier Transform Infrared spectroscopy (FT-IR). The effect of the structure features of cellulose-lignin hydrogels on their dehydration heat was evaluated by Differential Scanning Calorimetry (DSC). The Scanning Electron Microscopy (SEM) images reveal some morphological aspects of the hydrogels. The degree as well as the rate of swelling in a mixture of water:ethanol = 19:1 were estimated. The possible application of these hydrogels as controlled release systems was tested. Polyphenols known as having a wide range of biological effects were selected to be incorporated in such hydrogels by an optimal procedure. The extract of grapes seeds from the Chambourcin type was used as a source of polyphenols (PF). The amount of the incorporated polyphenols was estimated by UV-VIS measurements. Characterization of the hydrogels containing polyphenols was performed by FTIR spectroscopy. Some parameters were estimated based on the registered spectra, as H-bond energy (E{sub H}), the asymmetric index (a/b) and the enthalpy of H-bond formation ({Delta}H). The modifications of the thermal behavior and morphology induced by the presence of the polyphenols in hydrogels were highlighted by DSC and SEM, respectively. The release of polyphenols from CL hydrogels depended on the lignin content from matrices, as assessed by spectral studies. Both loading with polyphenols and their release can be controlled by the composition of the hydrogels. The kinetic of polyphenols release was studied. - Highlights: Black-Right-Pointing-Pointer A unique method to obtain cellulose-lignin hydrogels. Black-Right-Pointing-Pointer The application of these hydrogels as controlled release systems was tested. Black

  11. Development of honey hydrogel dressing for enhanced wound healing

    International Nuclear Information System (INIS)

    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

  12. Synthesis and Properties of the Metallo-Supramolecular Polymer Hydrogel Poly[methyl vinyl ether-alt-mono-sodium maleate]∙AgNO3

    KAUST Repository

    Al-Dossary, Mona S.

    2014-05-01

    Gels are a special class of materials which are composed of 3D networks of crosslinked polymer chains that encapsulate liquid/air in the matrix. They can be classified into organogels or hydrogels (organic solvent for organogel and water for hydrogel). For hydrogels that contain metallic elements in the form of ions, the term of metallo-supramolecular polymer hydrogel (MSPHG) is often used. The aim of this project is to develop a kind of new MSPHG and investigate its properties and possible applications. The commercial polymeric anhydride poly(methyl vinyl ether-alt-maleic anhydride) (PVM/MA) is converted by reaction with NaOH to give poly(methyl vinyl ether-alt-monosodium maleate) (PVM/Na-MA). By addition of AgNO3-solution, the formation of the silver(I) supramolecular polymer hydrogel poly[methyl vinyl ether-alt-mono-sodium maleate]∙AgNO3 is obtained. Freeze-dried samples of the hydrogel show a mesoporous network of polycarboxylate ligands that are crosslinked by silver(I) cations. The supercritical CO2 dried silver(I) hydrogel was characterized by FT-IR, SEM-EDAX, TEM, TGA and Physical adsorption (BET) measurements. The intact silver(I) hydrogel was characterized by cryo-SEM. In the intact hydrogel, ion-exchange studies are reported and it is shown that Ag+ ions can be exchanged by copper(II) cations without disintegration of the hydrogel. The silver(I) hydrogel shows effective antibacterial activity and potential application as burn wound dressing.

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

    Science.gov (United States)

    Xin, Lu Zhao; Carenza, Mario; Kaetsu, Isao; Kumakura, Minoru; Yoshida, Masaru; Fujimura, Takashi

    Polymer hydrogels were obtained by radiation-induced copolymerization at -78°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 polymerizing mixture.

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

    International Nuclear Information System (INIS)

    Polymer hydrogels were obtained by radiation-induced copolymerization at -78oC 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)

  15. Characterization of nitrate ions adsorption and diffusion in P(DMAEMA/HEMA) hydrogels

    Institute of Scientific and Technical Information of China (English)

    Yun Tian

    2008-01-01

    In this work, the adsorption and diffusion behavior of nitrate ions into polycationic P(DMAEMA/HEMA) hydrogels is analyzed. Experimental results indicated that nitrate ions can be removed efficiently from aqueous solutions. Adsorption isotherm of gels was well according to the Langmuir and Langmuir-Freundlich models. At the same time, the diffusion behavior of nitrate ions from P(DMAEMA/HEMA) hydrogels was investigated. The diffusion coefficients are strongly influenced by the changes of temperature and pH value of solutions. At the same time, D does not depend on the gels cross-linking ratio and initial solute concentration.

  16. 2.6. Sorption of serum albumin by ethynyl-piperidol hydrogels

    International Nuclear Information System (INIS)

    The sorption of serum albumin by ethynyl-piperidol hydrogels was studied in this article. Albumins adsorption on the surface of solids was considered. The capacity of cross-linked ethynyl piperidol polymers to the serum albumin was considered as well. The kinetic curves of sorption of human serum albumin by triple copolymer of isopropenyl trimethyl ethynyl piperidol were constructed. Sorption activity of ethynyl-piperidol polymers depending on ph of solution of human serum albumin were defined. Influence of solution ionic strength on sorption of human serum albumin was defined as well. The desorption of human serum albumin from the complexes with hydrogels was examined.

  17. Synthesis, characterization and application of biodegradable crosslinked carboxymethyl chitosan/poly(vinyl alcohol) clay nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Sabaa, Magdy W.; Abdallah, Heba M.; Mohamed, Nadia A.; Mohamed, Riham R., E-mail: rihamrashad@hotmal.com

    2015-11-01

    Crosslinked poly(vinyl alcohol) (PVA)/carboxymethyl chitosan (CMCh) nanocomposites were synthesized using terephthaloyl diisothiocyanate crosslinker, in the presence of montmorillonite (MMT), in different ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PVA hydrogels increased the swellability. Metal ion adsorption has also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non crosslinked CMCh. Antimicrobial activity was examined against Gram positive bacteria, against Gram negative bacteria, and also against fungi. Results indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation study was carried out in Simulated Body Fluid (SBF) for different time periods in order to find out degradation index (Di). Results showed that weight loss of most of the nanocomposites increased as a function of incubation time. - Highlights: • CMCh/PVA nanocomposites have been evaluated for activity against bacteria and fungi. • TEM showed that these hydrogels have size 3–19 nm. • Nanocomposites increased metal ion uptake and showed selectivity for cadmium ions. • Biodegradation increased as a function of incubation time in SBF solution. • Biodegradation increased with increase in CMCh and clay in nanocomposites.

  18. Synthesis, characterization and application of biodegradable crosslinked carboxymethyl chitosan/poly(vinyl alcohol) clay nanocomposites

    International Nuclear Information System (INIS)

    Crosslinked poly(vinyl alcohol) (PVA)/carboxymethyl chitosan (CMCh) nanocomposites were synthesized using terephthaloyl diisothiocyanate crosslinker, in the presence of montmorillonite (MMT), in different ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PVA hydrogels increased the swellability. Metal ion adsorption has also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non crosslinked CMCh. Antimicrobial activity was examined against Gram positive bacteria, against Gram negative bacteria, and also against fungi. Results indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation study was carried out in Simulated Body Fluid (SBF) for different time periods in order to find out degradation index (Di). Results showed that weight loss of most of the nanocomposites increased as a function of incubation time. - Highlights: • CMCh/PVA nanocomposites have been evaluated for activity against bacteria and fungi. • TEM showed that these hydrogels have size 3–19 nm. • Nanocomposites increased metal ion uptake and showed selectivity for cadmium ions. • Biodegradation increased as a function of incubation time in SBF solution. • Biodegradation increased with increase in CMCh and clay in nanocomposites

  19. Radiation chemical technology for production of polymeric hydrogels for medical purposes

    International Nuclear Information System (INIS)

    Full text: Polymeric hydrogels are water-swelling cross-linked hydrophilic polymers with ability to store reversibly great amount of water (more than 1000 g of water per 1 g of dry polymer). At present they found a lot of different applications in highly developed countries in science and industry. The set of unique physicochemical and biomedical properties (regulated sorption ability in respect to water and biological liquids, biocompatibility, soft tissue state, permeability in respect to small and big molecules, non-toxicity, etc.) allows their application in medicine. According to the clinical data there are no materials that can compete with hydrogels in development of endo-prostheses of soft-tissues in surgery, contact lenses for eyesight correction, hemo-compatible materials, novel for treatment of wounds and burns, targeted drug delivery systems. Polymeric hydrogels today practically substitute the traditional hydrophobic bases (Vaseline, lanolin) in technology of drug forms for development of ointments and dressings, containing natural and synthetic physiologically active substances. The advantages of hydrogels in comparison with hydrophobic analogues are obvious due to the drainage effect, homogenous distribution of drugs, better contact with wound, painless removing by water washing. The polymeric hydrogels are not produced in Kazakhstan in spite of the big source of raw materials. The aim of the present work is the development of radiation-chemical technology and development of polymeric biomedical hydrogels production based on raw materials of Kazakhstan. The novel types of polymeric hydrogel materials are developed by the authors of the report based on vinyl ethers of glycols, which produced in 'Alash Ltd.' (Temirtau). The great fundamental information content has been obtained about these monomers and polymers including direct quantitative data of their structure formation mechanism and physicochemical properties. These data served as a basis for

  20. Control of growth factor binding and release in bisphosphonate functionalized hydrogels guides rapid differentiation of precursor cells in vitro.

    Science.gov (United States)

    Kootala, Sujit; Zhang, Yu; Ghalib, Sara; Tolmachev, Vladimir; Hilborn, Jöns; Ossipov, Dmitri A

    2016-02-01

    An in situ cross-linkable hyaluronan hydrogel functionalized with bisphosphonate (BP) groups allows tunable release of bone morphogenetic protein-2 (BMP-2) determined by the amount of BP groups. The high affinity of matrix-anchored BP groups towards BMP-2 permits guided differentiation of entrapped progenitor cells in 3-D cultures. PMID:26610690

  1. Preparation and In Vitro Evaluation of a Stomach Specific Drug Delivery System based on Superporous Hydrogel Composite

    OpenAIRE

    Chavda, H.V.; Patel, C. N.

    2011-01-01

    This study discusses efforts made to design drug-delivery system based on superporous hydrogel composite for sustained delivery of ranitidine hydrochloride. The characterization studies involve measurement of apparent density, porosity, swelling studies, mechanical strength studies, and scanning electron microscopy. Scanning electron microscopic images clearly showed the formation of interconnected pores, capillary channels, and the cross-linked sodium carboxymethylcellulose molecules around ...

  2. Control of growth factor binding and release in bisphosphonate functionalized hydrogels guides rapid diff erentiation of precursor cells in vitro

    OpenAIRE

    Kootala, Sujit; Zhang, Yu; Ghalib, Sara; Tolmachev, Vladmir; Hilborn, Jöns; Ossipov, Dmitri

    2016-01-01

    An in situ cross-linkable hyaluronan hydrogel functionalized with bisphosphonate (BP) groups allows tunable release of bone morphogenetic protein-2 (BMP-2) determined by the amount of BP groups. The high affinity of matrix-anchored BP groups towards BMP-2 permits guided differentiation of entrapped progenitor cells in 3-D cultures.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. Electrically responsive materials based on polycarbazole/sodium alginate hydrogel blend for soft and flexible actuator application.

    Science.gov (United States)

    Sangwan, Watchara; Petcharoen, Karat; Paradee, Nophawan; Lerdwijitjarud, Wanchai; Sirivat, Anuvat

    2016-10-20

    The electromechanical properties, namely the storage modulus sensitivity and bending, of sodium alginate (SA) hydrogels and polycarbazole/sodium alginate (PCB/SA) hydrogel blends under applied electric field was investigated. The electromechanical properties of the pristine SA were studied under effects of crosslinking types and SA molecular weights, whereas the PCB/SA hydrogel blends were studied under the effect of PCB concentrations. The storage modulus sensitivity and bending of the pristine SA as crosslinked by the ionic crosslinking agent were found to be higher than those of the covalent crosslinking. The storage modulus sensitivity and deflection of the SA increased monotonically with increasing molecular weight. The highest electromechanical response of the PCB/SA hydrogel blends was obtained from the blend with 0.10% v/v PCB as it provided surprisingly the highest ever storage modulus sensitivity, (G'-G'0)/G'0 where G'0 and G' are the storage modulus without and with applied electric field, respectively, at 18.5 under applied electric field strength of 800V/mm. PMID:27474560

  5. Injectable In Situ Forming Hybrid Iron Oxide-Hyaluronic Acid Hydrogel for Magnetic Resonance Imaging and Drug Delivery

    NARCIS (Netherlands)

    Zhang, Y; Sun, Y.; Yang, X.; Hilborn, J.; Heerschap, A.; Ossipov, D.A.

    2014-01-01

    The development of multimodal in situ cross-linkable hyaluronic acid nanogels hybridized with iron oxide nanoparticles is reported. Utilizing a chemoselective hydrazone coupling reaction, the nanogels are converted to a macroscopic hybrid hydrogel without any additional reagent. Hydrophobic cargos r

  6. Increasing Thermal Stability of Gelatin by UV-Induced Cross-Linking with Glucose

    Directory of Open Access Journals (Sweden)

    Evan M. Masutani

    2014-01-01

    Full Text Available The effects of ultraviolet (254 nm radiation on a hydrated gelatin-glucose matrix were investigated for the development of a physiologically thermostable substrate for potential use in cell scaffold production. Experiments conducted with a differential scanning calorimeter indicate that ultraviolet irradiation of gelatin-glucose hydrogels dramatically increases thermal stability such that no melting is observed at temperatures of at least 90°C. The addition of glucose significantly increases the yield of cross-linked product, suggesting that glucose has a role in cross-link formation. Comparisons of lyophilized samples using scanning electron microscopy show that irradiated materials have visibly different densities.

  7. Photoinitiator-free synthesis of endothelial cell-adhesive and enzymatically degradable hydrogels.

    Science.gov (United States)

    Jones, Derek R; Marchant, Roger E; von Recum, Horst; Sen Gupta, Anirban; Kottke-Marchant, Kandice

    2015-02-01

    We report on a photoinitiator-free synthetic method of incorporating bioactivity into poly(ethylene glycol) (PEG) hydrogels in order to control physical properties, enzymatic biodegradability and cell-specific adhesiveness of the polymer network, while eliminating the need for UV-mediated photopolymerization. To accomplish this, hydrogel networks were polymerized using Michael addition with four-arm PEG acrylate (10 kDa), using a collagenase-sensitive peptide (CSP) as a crosslinker, and introducing an endothelial cell-adhesive peptide either terminally (RGD) or attached to the crosslinking peptide sequence (CSP-RGD). The efficiency of the Michael addition reactions were determined by nuclear magnetic resonance and Ellman's assay. Successful decoupling of cell adhesivity and physical properties was demonstrated by quantifying and comparing the swelling ratios and Young's moduli of various hydrogel formulations. Degradation profiles were established by incubating functionalized hydrogels in collagenase solutions (0.0-1.0 μg ml(-1)), demonstrating that functionalized hydrogels degraded at a rate dependent upon collagenase concentration. Moreover, it was shown that the degradation rate was independent of CSP-RGD concentration. Cell attachment and proliferation on functionalized hydrogels were compared for various RGD concentrations, providing evidence that cell attachment and proliferation were directly related to relative amounts of the CSP-RGD combination peptide. An increase in cell viability was achieved using Michael addition techniques when compared to UV polymerization, and was assessed by a LIVE/DEAD fluorescence assay. This photoinitiator-free method shows promise in creating hydrogel-based tissue engineering scaffolds allow for decoupled cell adhesivity and physical properties and that render greater cell viability. PMID:25462848

  8. Preparation and characterization of superporous hydrogels as gastroretentive drug delivery system for rosiglitazone maleate

    Directory of Open Access Journals (Sweden)

    N Vishal Gupta

    2010-09-01

    Full Text Available "n  "nBackground and the purpose of the study: Many drugs which have narrow therapeutic window and are absorbed mainly in stomach have been developed as gastroretentive delivery system. Rosiglitazone maleate, an anti-diabetic, is highly unstable at basic pH and is extensively absorbed from the stomach. Hence there is a need to develop a gastroretentive system. In this study a superporous hydrogel was developed as a gastroretentive drug delivery system. "nMethods: Chitosan/poly(vinyl alcohol interpenetrating polymer network type superporous hydrogels were prepared using a gas foaming method employing glyoxal as the crosslinking agent for Rosiglitazone maleate. Sodium bicarbonate was applied as a foaming agent to introduce the porous structure. Swelling behaviors of superporous hydrogel in acidic solution were studied to investigate their applications for gastric retention device. The optimum preparation condition of superporous hydrogels was obtained from the gelation kinetics. FT-IR, scanning electron microscopy, porosity and swelling ratio studies were used to characterize these polymers. In vitro drug release studies were also carried out. "nResults: The introduction of a small amount of Poly(Vinyl Alcohol enhanced the mechanical strength but slightly reduced the swelling ratio. The prepared superporous hydrogels were highly sensitive to pH of swelling media, and showed reversible swelling and de-swelling behaviors maintaining their mechanical stability. The degradation kinetics in simulated gastric fluid showed that it had biodegradability. Swelling was dependent on the amount of chitosan and crosslinker. The drug release from superporous hydrogels was sustained for 6 hrs. Major Conclusion: The studies showed that chitosan-based superporous hydrogels could be used as a gastroretentive drug delivery system for rosiglitazone maleate in view of their swelling and prolonged drug release characteristics in acidic pH.

  9. Engineering hyaluronic acid hydrogel degradation to control cellular interactions and adult stem cell fate in 3D

    Science.gov (United States)

    Khetan, Sudhir

    The design and implementation of extracellular matrix (ECM)-mimetic hydrogels for tissue engineering (TE) applications requires an intensive understanding of cell-material interactions, including matrix remodeling and stem cell differentiation. However, the influence of microenvironmental cues, e.g., matrix biodegradability, on cell behavior in vitro has not been well studied in the case of direct cell encapsulation within 3-dimensional (3D) hydrogels. To address these issues, a facile sequential crosslinking technique was developed that provides spatial and temporal control of 3D hydrogel degradability to investigate the importance of material design on cell behavior. Specifically, hydrogels were synthesized from hyaluronic acid (HA) macromers in a sequential process: (1) a primary Michael-type addition crosslinking using cell adhesive and matrix metalloprotease (MMP)-degradable oligopeptides to consume a portion of total reactive groups and resulting in "-UV" hydrogels permissive to cell-mediated degradation, followed by (2) a secondary, light initiated free-radical crosslinking to consume remaining reactive groups and "switch" the network to a non-degradable structure ("+UV") via the addition of non-degradable kinetic chains. Using this approach, we demonstrated control of encapsulated hMSC spreading by varying the crosslink type (i.e., the relative hydrogel biodegradability), including with spatial control. Upon incubation with bipotential soluble differentiation factors, these same degradation-mediated spreading cues resulted in an hMSC differentiation fate switch within -UV versus +UV environments. Follow-up studies demonstrated that degradation-mediated traction generation, rather than matrix mechanics or cell morphology, is the critical biophysical signal determining hMSC fate. Sequentially crosslinked HA hydrogels were also studied for the capacity to support remodeling by in vivo and ex vivo tissues, including with spatial control, toward tissue

  10. Injectable carboxymethylcellulose hydrogels for soft tissue filler applications.

    Science.gov (United States)

    Varma, Devika M; Gold, Gittel T; Taub, Peter J; Nicoll, Steven B

    2014-12-01

    Disease, trauma and aging all lead to deficits in soft tissue. As a result, there is a need to develop materials that safely and effectively restore areas of deficiency. While autogenous fat is the current gold standard, hyaluronic acid (HA) fillers are commonly used. However, the animal and bacterial origin of HA-based materials can induce adverse reactions in patients. With the aim of developing a safer and more affordable alternative, this study characterized the properties of a plant-derived, injectable carboxymethylcellulose (CMC) soft tissue filler. Specifically, methacrylated CMC was synthesized and crosslinked to form stable hydrogels at varying macromer concentrations (2-4% w/v) using an ammonium persulfate and ascorbic acid redox initiation system. The equilibrium Young's modulus was shown to vary with macromer concentration (ranging from ∼2 to 9.25kPa), comparable to values of native soft tissue and current surgical fillers. The swelling properties were similarly affected by macromer concentration, with 4% gels exhibiting the lowest swelling ratio and mesh size, and highest crosslinking density. Rheological analysis was performed to determine gelation onset and completion, and was measured to be within the ISO standard for injectable materials. In addition, hydrolytic degradation of these gels was sensitive to macromer concentration, while selective removal using enzymatic treatment was also demonstrated. Moreover, favorable cytocompatibility of the CMC hydrogels was exhibited by co-culture with human dermal fibroblasts. Taken together, these findings demonstrate the tunability of redox-crosslinked CMC hydrogels by varying fabrication parameters, making them a versatile platform for soft tissue filler applications. PMID:25152355

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

    Directory of Open Access Journals (Sweden)

    Ibrahim M. El-Sherbiny

    2011-01-01

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

  12. Biomimetic macroporous hydrogels

    Czech Academy of Sciences Publication Activity Database

    Sedlačík, Tomáš; Proks, Vladimír; Šlouf, Miroslav; Studenovská, Hana; Dušková, Miroslava; Rypáček, František

    Prague : Institute of Macromolecular Chemistry AS CR, 2015. s. 69. ISBN 978-80-85009-82-8. [Functional Polymers at Bio -Material Interfaces - 79th Prague Meeting on Macromolecules. 28.06.2015-02.07.2015, Prague] Institutional support: RVO:61389013 Keywords : click chemistry * hydrogels Subject RIV: CD - Macromolecular Chemistry

  13. Novel composite sorbent AAm/MA hydrogels containing starch and kaolin for water sorption and dye uptake

    Indian Academy of Sciences (India)

    Erdener Karadağ; Fulya Topaç; Semıha Kundakci; ÖMER Bariş Üzüm

    2014-12-01

    A novel polymer/clay composite sorbent based on acrylamide/maleic acid, starch and clay such as kaolin was synthesized with free radical solution polymerization by using ammonium persulfate/,,','-tetramethylethylenediamine as redox initiating pair in the presence of poly(ethylene glycol)diacrylate as a crosslinker. Surface morphology was characterized by the scanning electron microscopy technique. FT-IR analysis was used to identify the presence of different repeating units in the semi-interpenetrating polymer networks (semi-IPNs). Some swelling and diffusion characteristics were calculated for different semi-IPNs and hydrogels prepared under various formulations. The hydrogels were used in experiments on sorption of water-soluble cationic dye such as toluidine blue. Sorption of toluidine blue into the polymeric systems was studied by the batch sorption technique at 25 °C. Water uptake and dye sorption properties of the crosslinked polymeric systems were investigated as a function of chemical composition of the hydrogels.

  14. The development of photochemically crosslinked native fibrinogen as a rapidly formed and mechanically strong surgical tissue sealant.

    Science.gov (United States)

    Elvin, Christopher M; Brownlee, Alan G; Huson, Mickey G; Tebb, Tracy A; Kim, Misook; Lyons, Russell E; Vuocolo, Tony; Liyou, Nancy E; Hughes, Timothy C; Ramshaw, John A M; Werkmeister, Jerome A

    2009-04-01

    We recently reported the generation of a highly elastic, crosslinked protein biomaterial via a rapid photochemical process using visible light illumination. In light of these findings, we predicted that other unmodified, tyrosine-rich, self-associating proteins might also be susceptible to this covalent crosslinking method. Here we show that unmodified native fibrinogen can also be photochemically crosslinked into an elastic hydrogel biomaterial through the rapid formation of intermolecular dityrosine. Photochemically crosslinked fibrinogen forms tissue sealant bonds at least 5-fold stronger than commercial fibrin glue and is capable of producing maximum bond strength within 20s. In vitro studies showed that components of the photochemical crosslinking reaction are non-toxic to cells. This material will find useful application in various surgical procedures where rapid curing for high strength tissue sealing is required. PMID:19147224

  15. Multifunctional Hydrogel Microparticles by Polymer-Assisted Photolithography.

    Science.gov (United States)

    Li, Bin; He, Muhan; Ramirez, Lisa; George, Justin; Wang, Jun

    2016-02-17

    Although standard lithography has been the most common technique in micropatterning, ironically it has not been adopted to produce multifunctional hydrogel microparticles, which are highly useful for bioassays. We address this issue by developing a negative photoresist-like polymer system, which is basically comprised of polyethylene glycol (PEG) triacrylate as cross-linking units and long-chain polyvinylpyrrolidone (PVP) as the supporting scaffold. We leverage standard lithography to manufacture multilayer microparticles that are intrinsically hydrophilic, low-autofluorescent, and chemically reactive. The versatility of the microparticles is demonstrated to be color-encoded, pore-controllable, bioactive, and potentially used as a DNA bioassay. PMID:26821173

  16. Redox-active cross-linkable poly(ionic liquid)s.

    Science.gov (United States)

    Sui, Xiaofeng; Hempenius, Mark A; Vancso, G Julius

    2012-03-01

    The synthesis of a new class of cross-linkable redox-responsive poly(ferrocenylsilane)-based poly(ionic liquid)s (PFS-PILs) is reported. PFS-PILs self-cross-link at low concentrations into nanogels or form macroscopic hydrogel networks at higher concentrations. PFS-PILs proved to be efficient dispersants in the microemulsion polymerization of methyl methacrylate, producing stable PFS-poly(methyl methacrylate) latex suspensions. PMID:22353019

  17. Controlling the kinetics of thiol-maleimide Michael-type addition gelation kinetics for the generation of homogenous poly(ethylene glycol) hydrogels.

    Science.gov (United States)

    Darling, Nicole J; Hung, Yiu-Sun; Sharma, Shruti; Segura, Tatiana

    2016-09-01

    The development of synthetic hydrogels analogs for the extracellular matrix has proven a useful and important tool to study the role of specific signals on biological outcomes in vitro and to serve as scaffolds for tissue repair. Although the importance of physical properties (e.g. microstructure and stiffness) in the micro and nano scale on cell fate has been widely reported, bulk modulus measurements are typically used to characterize hydrogels. Thus, the physical properties of hydrogels have not been widely tested for their controlled physical properties in the nano and micron scales. In this report, we show that although fast Michael-type addition crosslinked hydrogels appear uniform by bulk modulus readings and visual inspection, they are non-uniform in the micron scale, with high and low crosslinking regions. Further, we show that these regions of high and low crosslinking result in differences in cellular behavior. Since these regions are random in density and shape, this leads to misleading cellular responses. These inconsistences are most widely observed when the gel forms faster than the material can be mixed. This study slows the gelation rate of thiol-maleimide cross-linked hydrogels in order to overcome the cellular response variability between batches. PMID:27289380

  18. A Shape-Memory DNA-Based Hydrogel Exhibiting Two Internal Memories.

    Science.gov (United States)

    Hu, Yuwei; Guo, Weiwei; Kahn, Jason S; Aleman-Garcia, Miguel Angel; Willner, Itamar

    2016-03-18

    The synthesis of a shape-memory acrylamide-DNA hydrogel that includes two internal memories is introduced. The hydrogel is stabilized, at pH 7.0, by two different pH-responsive oligonucleotide crosslinking units. At pH 10.0, one of the T-A⋅T triplex DNA bridging units is dissociated, resulting in the dissociation of the hydrogel into a shapeless quasi-liquid state that includes the other oligonucleotide bridges as internal memory. Similarly, at pH 5.0, the second type of bridges is separated, through the formation of C-G⋅C(+) triplex units to yield the shapeless quasi-liquid state that includes the other oligonucleotide bridges as internal memory. By reversible pH triggering of the hydrogel between the values 10.0⇔7.0⇔5.0, the two internal memories cycle the material across shaped hydrogel and shapeless quasi-liquid states. The two memories enable the pH-dictated formation of two different hydrogel structures. PMID:26915713

  19. OPTIMIZATION OF THE SYNTHESIS OF ACRYLAMIDE HYDROGEL BY γ-RAY IRRADIATION

    Institute of Scientific and Technical Information of China (English)

    M.A. Chowdhury; M.M. Alam; M.F. Mina; F. Akhtar; S.E. Kabir

    2004-01-01

    Hydrogels have been synthesized from 10%, 20%, 30%, 40%, 50% and 60% aqueous solutions of acrylamide monomer by gamma radiation employing doses in the range of 0.2-30 kGy from a Co-60 source. The effect of solution concentration, γ-ray dose, pH and time was studied in order to observe the optimizing conditions in the characterization of hydrogels. Gel fraction increases with dose for all concentrations indicating hundred-percentage conversion of gel at doses ≥5 kGy for homogenous solutions in the range of 20%-50% concentration. On the other hand, 10% solution provides conversion less than 86% even at 30 kGy, whereas 60% monomer makes an inhomogeneous solution which stile gives about 100% gel fraction. Swelling of hydrogels under water with respect to time varies with both the doses and concentrations due to the change of crosslinking density in the gels. The maximum volume change of hydrogels during swelling and water desorption mainly occurs within 24 h. Swelling is also enhanced with the rise of pH due to change of ionic content of the solvent. Considering the amount of gel fraction and the properties of hydrogel, the samples prepared from 20% solution at 5kGy show better results. Moreover, the effect of bacteria on hydrogel was found to be nil, suggesting a prohibition of growth of microorganism in it.

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

    International Nuclear Information System (INIS)

    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

  1. SWELLING BEHAVIOR OF ACRYLAMIDE HYDROGEL IN DIFFERENT SOLVENTS AND pHs

    Institute of Scientific and Technical Information of China (English)

    M. F. Mina; M. M. Alam

    2005-01-01

    Swelling property of acrylamide hydrogels, prepared from aqueous solutions of acrylamide monomer having concentrations in the range of 10-60 wt% by γ-ray irradiation method using a Co-60 gamma radiation source at doses ranging 1-30.0 kGy, has been investigated under various swelling media. These swelling media were basically solvents (solutions), produced by dissolving methanol, ethanol, glucose, sucrose, sodium chloride and sodium persulfate individually with distilled water, and solutions prepared with phs = 3, 7 and 10. The investigation was performed in order to observe the effect of these solvents and phs as well as the influence of monomer concentrations, radiation doses and times on swelling behavior of hydrogels. Swelling values were found higher for hydrogels prepared with lower monomer concentrations (ca.20 wt%) and radiation doses (ca. 5 kGy) and showed a leveling off tendency within 24 h. The glucose solvent and the buffer solution of pH = 10 revealed significant increase of swelling of hydrogels as compared to other solutions. Results are explained based on crosslinking density in hydrogel, polymer-solvent/polymer-polymer interactions in solutions,permeability of molecules in solutions and ionization capacity of hydrogel in pH.

  2. Aptamer-functionalized hydrogel as effective anti-cancer drugs delivery agents.

    Science.gov (United States)

    Wang, Zonghua; Xia, Jianfei; Cai, Feng; Zhang, Feifei; Yang, Min; Bi, Sai; Gui, Rijun; Li, Yanhui; Xia, Yanzhi

    2015-10-01

    An aptamer-functionalized hydrogel has been developed, which can be regulated by the AS1411 aptamer with the sol-gel conversion. Also the hydrogel can be further utilized for the controlled encapsulation and release of the cancer drugs. Specially, the AS1411 initiates the hybridization of acrydite-modified oligonucleotides to form the hydrogels and the presence of the target protein nucleolin leads the gel to dissolve as a result of reducing the cross-linking density by competitive target-aptamer binding. Based on the rheology of hydrogels, it is possible to utilize this material for storing and releasing molecules. In this research, the cancer drug doxorubicin is encapsulated inside the gel during the formation of the hydrogel and then released in the presence of nucleolin. Further experiments are carried out to prove the specific recognition of target matter. In vitro researches confirm that the aptamer-functionalized hydrogels can be used as drug carriers in targeted therapy and other biotechnological applications. PMID:26142627

  3. Nanocomposite hydrogels based on water soluble polymer and montmorillonite-Na+

    Directory of Open Access Journals (Sweden)

    Fatiha Reguieg

    2015-09-01

    Full Text Available A series of composites hydrogels based on Poly (1,3-dioxolane (PDXL,water soluble polymer, were synthesized directly in water by free-radical homopolymerization of a,w-methacryloyloxy PDXL macromonomers using hydrophilic sodium Montmorillonite clay: Maghnite-Na+ (Mag-Na+ and potassium persulfate as an initiator. These materials were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, thermogravimetric analysis (ATG and their equilibrium swelling behavior in water and were compared with those of pure hydrogels prepared without Mag-Na+. X-ray diffraction and Infrared spectroscopy confirmed insertion of clay into polymer. The thermal decomposition temperature of the hydrogels based on maghnite-Na+ was found to be higher than of pure hydrogels. At the same time, the influence of the macromonomer precursor molar mass value, its concentration and the quantities of Mag-Na+, on the values of the volume degree of equilibrium swelling were studied. The results showed that the volume degree of equilibrium swelling was investigated as a function of the clay content. However, whether the concentration of macromonomer precursor increased, the volume or weight degree of equilibrium swelling of hydrogels all decreased. The addition of Mag-Na+ particles changed the crosslinking density of hydrogels.

  4. Synthesis, properties, and biomedical applications of gelatin methacryloyl (GelMA) hydrogels.

    Science.gov (United States)

    Yue, Kan; Trujillo-de Santiago, Grissel; Alvarez, Mario Moisés; Tamayol, Ali; Annabi, Nasim; Khademhosseini, Ali

    2015-12-01

    Gelatin methacryloyl (GelMA) hydrogels have been widely used for various biomedical applications due to their suitable biological properties and tunable physical characteristics. GelMA hydrogels closely resemble some essential properties of native extracellular matrix (ECM) due to the presence of cell-attaching and matrix metalloproteinase responsive peptide motifs, which allow cells to proliferate and spread in GelMA-based scaffolds. GelMA is also versatile from a processing perspective. It crosslinks when exposed to light irradiation to form hydrogels with tunable mechanical properties. It can also be microfabricated using different methodologies including micromolding, photomasking, bioprinting, self-assembly, and microfluidic techniques to generate constructs with controlled architectures. Hybrid hydrogel systems can also be formed by mixing GelMA with nanoparticles such as carbon nanotubes and graphene oxide, and other polymers to form networks with desired combined properties and characteristics for specific biological applications. Recent research has demonstrated the proficiency of GelMA-based hydrogels in a wide range of tissue engineering applications including engineering of bone, cartilage, cardiac, and vascular tissues, among others. Other applications of GelMA hydrogels, besides tissue engineering, include fundamental cell research, cell signaling, drug and gene delivery, and bio-sensing. PMID:26414409

  5. SYNTHESIS AND CHARACTERIZATION OF AMPHOTERIC HYDROGELS BASED ON N-CARBOXYETHYLCHITOSAN

    Institute of Scientific and Technical Information of China (English)

    Yan Li; Qiang Yin; Ming-yu Deng; Jun-jie Cui; Bo Jiang

    2009-01-01

    New amphoteric hydrogels based on carboxyethylchitosans (CECH) with various degrees of substitution (DS) were prepared using different amounts of epichlorohydrin (ECH) as the crosslinking agent. The equilibrium swelling ratio (SW) was determined as functions of pH and salt concentration. The hydrogels show typical amphoteric character responding to pH change of the external medium. At isoelectric point (IEP), the hydrogels shrink. The DS value has important effect on the swelling properties of the hydrogels. When the DS of N-carboxyethylchitosan increases from 0.32 to 0.72, the equilibrium swelling ratio (SW) of the hydrogel changes from 76 to 290 at pH 7.3 and from 117 to 499 at pH 11.3. A marked volume decrease was observed in hydrogels with increasing salt concentration in the surrounding solution. The viscoelastic properties of the hydrogeis were studied by oscillatory shear measurements under small-deformation conditions. The elastic modulus G' of all the samples has no dependence on frequency and is one order of magnitude larger than the loss modulus G", corresponding to a strong gel behavior.

  6. Highly swelling hydrogels from ordered galactose-based polyacrylates.

    Science.gov (United States)

    Martin, B D; Linhardt, R J; Dordick, J S

    1998-01-01

    High swelling galactose-based hydrogels have been prepared using a chemoenzymatic procedure. Regioselective acylation of beta-O-methyl-galactopyranoside in nearly anhydrous pyridine with lipase from Pseudomonas cepacia yields the 6-acryloyl derivative (Compound I). Further lipase-catalysed acylation of the monoacrylate derivative in nearly anhydrous acetone yielded 2,6-diacryloyl-beta-O-methyl galactopyranoside (Compound II) that can act as a cross-linker with a structure similar to that of the sugar-based monomer. The high selectivity of enzyme catalysis yielded apparently highly regular hydrogel networks with swelling ratios at equilibrium ranging from 170 to 1100. elastic moduli ranging from 0.005 to 0.088 MPa and calculated mesh sizes ranging from 1160 to 6600 A. These values are far higher than conventional uncharged or lightly charged hydrogels at similar elastic moduli. Gel swelling was fast, with 75% of the equilibrium swelling value reached in a fractional time of 0.17. Non-selective chemical acryloylation of beta-O-methyl galactopyranoside followed by polymerization yielded a far lower-swelling hydrogel than that obtained using selective enzyme catalysis. These results indicate that the highly regular polymer structure achieved by regioselective enzyme-catalysed acylation yields relatively strong and highly swellable materials. Sugar-based hydrogels, such as those described herein, may find particular use as biomaterials because of their high water content, homogeneity, stability and expected non-toxicity. A wide range of pore sizes can be attained, suggesting that they may also be especially useful as matrices for enzyme immobilization and controlled delivery of biological macromolecules. PMID:9678852

  7. Superporous polyacrylate/chitosan IPN hydrogels for protein delivery.

    Science.gov (United States)

    Gümüşderelioğlu, Menemşe; Erce, Deniz; Demirtaş, T Tolga

    2011-11-01

    In this study, poly(acrylamide), poly(AAm), and poly(acrylamide-co-acrylic acid), poly(AAm-co-AA) superporous hydrogels (SPHs) were synthesized by radical polymerization in the presence of gas blowing agent, sodium bicarbonate. In addition, ionically crosslinked chitosan (CH) superporous hydrogels were synthesized to form interpenetrating superporous hydrogels, i.e. poly(AAm)-CH and poly(AAm-co-AA)-CH SPH-IPNs. The hydrogels have a structure of interconnected pores with pore sizes of approximately 100-150 μm. Although the extent of swelling increased when AA were incorporated to the poly(AAm) structure, the time to reach the equilibrium swelling (~30 s) was not affected so much. In the presence of chitosan network mechanical properties significantly improved when compared with SPHs, however, equilibrium swelling time (~30 min) was prolonged significantly as due to the lower porosities and pore sizes of SPH-IPNs than that of SPHs. Model protein bovine serum albumin (BSA) was loaded into SPHs and SPH-IPNs by solvent sorption in very short time (<1 h) and very high capacities (~30-300 mg BSA/g dry gel) when compared to conventional hydrogels. BSA release profiles from SPHs and SPH-IPNs were characterized by an initial burst of protein during the first 20 min followed by a completed release within 1 h. However, total releasable amount of BSA from SPH-IPNs was lower than that of SPHs as due to the electrostatic interactions between chitosan and BSA. PMID:21901372

  8. Structural Analysis and Mechanical Characterization of Hyaluronic Acid-Based Doubly Cross-Linked Networks.

    Science.gov (United States)

    Jha, Amit K; Hule, Rohan A; Jiao, Tong; Teller, Sean S; Clifton, Rodney J; Duncan, Randall L; Pochan, Darrin J; Jia, Xinqiao

    2009-01-01

    We have created a new class of hyaluronic acid (HA)-based hydrogel materials with HA hydrogel particles (HGPs) embedded in and covalently cross-linked to a secondary network. HA HGPs with an average diameter of ∼900 nm and narrow particle size distribution were synthesized using a refined reverse micelle polymerization technique. The average mesh size of the HGPs was estimated to be approximately 5.5 to 7.0 nm by a protein uptake experiment. Sodium periodate oxidation not only introduced aldehyde groups to the particles but also reduced the average particle size. The aldehyde groups generated were used as reactive handles for subsequent cross-linking with an HA derivative containing hydrazide groups. The resulting macroscopic gels contain two distinct hierarchical networks (doubly cross-linked networks, DXNs): one within individual particles and another among different particles. Bulk gels (BGs) formed by direct mixing of HA derivatives with mutually reactive groups were included for comparison. The hydrogel microstructures were collectively characterized by microscopy and neutron scattering techniques. Their viscoelasticity was quantified at low frequencies (0.1-10 Hz) using a controlled stress rheometer and at high frequencies (up to 200 Hz) with a home-built torsional wave apparatus. Both BGs and DXNs are stable elastic gels that become stiffer at higher frequencies. The HA-based DXN offers unique structural hierarchy and mechanical properties that are suitable for soft tissue regeneration. PMID:20046226

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

    OpenAIRE

    Liwei Tan; Xu Xu; Jia Song; Feng Luo; Zhiyong Qian

    2013-01-01

    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 i...

  10. Improve Cloud Temperature of Radiation Prepared Hydrogels Based on Poly(N-Isopropylacrylamide) by Addition of N,N-Dimethylacrylamide Monomer

    International Nuclear Information System (INIS)

    The poly(N-isopropylacrylamide) (PNIPAM) based hydrogels are typical thermosensitive material, which can be successfully synthesized from aqueous solution of NIPAM by radiation polymerization and cross-linking. Adding of N,N dimethylacrylamide (DMA) a hydrophilic monomer into the solution of reactant before irradiation much improved the cloud temperature of the created hydrogels. The phase transition temperature as well as swelling degree of hydrogel based on PNIPAM-DMA copolymer also depended on the ratio of DMA. Chemical structure of hydrogel P(NIPAM-co-DMA) were verified by proton spectroscopy (1H-NMR). The themosensivity of hydrogels was also investigated and the results showed that the low cloud temperature (Tp) is around of 37-40 oC. (author)

  11. Persulfate initiated ultra-low cross-linked poly(N-isopropylacrylamide) microgels possess an unusual inverted cross-linking structure.

    Science.gov (United States)

    Virtanen, O L J; Mourran, A; Pinard, P T; Richtering, W

    2016-05-01

    Cross-linking density and distribution are decisive for the mechanical and other properties of stimuli-sensitive poly(N-isopropylacrylamide) microgels. Here we investigate the structure of ultra-low cross-linked microgels by static light scattering and scanning force microscopy, and show that they have an inverted cross-linking structure with respect to conventional microgels, contrary to what has been assumed previously. The conventional microgels have the largest polymer volume fraction in the core from where the particle density decays radially outwards, whereas ultra-low cross-linked particles have the highest polymer volume fraction close to the surface. On a solid substrate these particles form buckled shapes at high surface coverage, as shown by scanning force micrographs. The special structure of ultra-low cross-linked microgels is attributed to cross-linking of the particle surface, which is exposed to hydrogen abstraction by radicals generated from persulfate initiators during and after polymerization. The particle core, which is less accessible to the diffusion of radicals, has consequently a lower polymer volume fraction in the swollen state. By systematic variation of the cross-linker concentration it is shown that the cross-linking contribution from peroxide under typical synthesis conditions is weaker than that from the use of 1 mol% N,N'-methylenebisacrylamide. Soft deformable hydrogel particles are of interest because they emulate biological tissues, and understanding the underlying synthesis principle enables tailoring the microgel structure for biomimetic applications. Deformability of microgels is usually controlled by the amount of added cross-linker; here we however highlight an alternative approach through structural softness. PMID:27033731

  12. Development and Characterization of UHMWPE Fiber-Reinforced Hydrogels For Meniscal Replacement

    Science.gov (United States)

    Holloway, Julianne Leigh

    Meniscal tears are the most common orthopedic injuries to the human body. The current treatment of choice, however, is a partial meniscectomy that leads to osteoarthritis proportional to the amount of tissue removed. As a result, there is a significant clinical need to develop materials capable of restoring the biomechanical contact stress distribution to the knee after meniscectomy and preventing the onset of osteoarthritis. In this work, a fiber-reinforced hydrogel-based synthetic meniscus was developed that allows for tailoring of the mechanical properties and molding of the implant to match the size, shape, and property distribution of the native tissue. Physically cross-linked poly(vinyl alcohol) (PVA) hydrogels were reinforced with ultrahigh molecular weight polyethylene (UHMWPE) fibers and characterized in compression (0.1-0.8 MPa) and tension (0.1-250 MPa) showing fine control over mechanical properties within the range of the human meniscus. Morphology and crystallinity analysis of PVA hydrogels showed increases in crystallinity and PVA densification, or phase separation, with freeze-thaw cycles. A comparison of freeze-thawed and aged, physically cross-linked hydrogels provided insight on both crystallinity and phase separation as mechanisms for PVA gelation. Results indicated both mechanisms independently contributed to hydrogel modulus for freeze-thawed hydrogels. In vitro swelling studies were performed using osmotic solutions to replicate the swelling pressure present in the knee. Minimal swelling was observed for hydrogels with a PVA concentration of 30-35 wt%, independently of hydrogel freeze-thaw cycles. This allows for independent tailoring of hydrogel modulus and pore structure using freeze-thaw cycles and swelling behavior using polymer concentration to match a wide range of properties needed for various soft tissue applications. The UHMWPE-PVA interface was identified as a significant weakness. To improve interfacial adhesion, a novel

  13. Radiation preparation and characterization of temperature- and pH-sensitive hydrogel of N-isopropylacrylamide/β-cyclodextrin copolymer

    International Nuclear Information System (INIS)

    A hydrogel copolymer of N-isopropylacrylamide/β-cyclodextrin was prepared by radiation copoly- merization method. β-cyclodextrin (β-CD) based monomer (MAH-β-CD) containing vinyl and carboxyl functional groups was synthesized by modification of β-CD with maleic anhydride (MAH). And then the mixture aqueous solution of NIPAAm and MAH-β-CD was irradiated by electron beams with BIS as cross-linking agent for sample of poly (NIPAAm-co-MAH-β-CD) hydrogel. The effects of temperature, pH and ionic strength on swelling ratio of the hydrogel were determined meanwhile the effect of irradiation absorbed doses on its swelling and deswelling properties was also described. Experimental results show that the copolymer hydrogel possesses temperature, pH and ionic strength sensitive functions. (authors)

  14. Synthesis and properties of a novel pH sensitive poly(N-vinyl-pyrrolidone-co-sulfadiazine hydrogel

    Directory of Open Access Journals (Sweden)

    2007-03-01

    Full Text Available Sulfadiazine monomer (SDM was synthesized by the reaction of sulfadiazine with acryloyl chloride. The SDM was characterized by 1H-NMR and IR spectra. A novel hydrogel with –SO2NH- group was obtained by the radical copolymerization of SDM with N-vinyl-pyrrolidone (NVP. Effects of the reaction temperature, reaction time, the monomer ratio, and the amount of the cross-linker on the pH sensitivity of the hydrogel were investigated. Results indicate that the hydrogel shows strong pH sensitivity in the pH range of 6.5 to 7.2. It also exhibits a good swelling reversibility at buffer solutions of pH 6.5 and 7.2. At last, drugs tests demonstrated the release effect of the hydrogel in pH range of 6.5 to 7.2.

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

    International Nuclear Information System (INIS)

    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

  16. Elastin based cell-laden injectable hydrogels with tunable gelation, mechanical and biodegradation properties.

    Science.gov (United States)

    Fathi, Ali; Mithieux, Suzanne M; Wei, Hua; Chrzanowski, Wojciech; Valtchev, Peter; Weiss, Anthony S; Dehghani, Fariba

    2014-07-01

    Injectable hydrogels made from extracellular matrix proteins such as elastin show great promise for various biomedical applications. Use of cytotoxic reagents, fixed gelling behavior, and lack of mechanical strength in these hydrogels are the main associated drawbacks. The aim of this study was to develop highly cytocompatible and injectable elastin-based hydrogels with alterable gelation characteristics, favorable mechanical properties and structural stability for load bearing applications. A thermoresponsive copolymer, poly(N-isopropylacrylamide-co-polylactide-2-hydroxyethyl methacrylate-co-oligo(ethylene glycol)monomethyl ether methacrylate, was functionalized with succinimide ester groups by incorporating N-acryloxysuccinimide monomer. These ester groups were exploited to covalently bond this polymer, denoted as PNPHO, to different proteins with primary amine groups such as α-elastin in aqueous media. The incorporation of elastin through covalent bond formation with PNPHO promotes the structural stability, mechanical properties and live cell proliferation within the structure of hydrogels. Our results demonstrated that elastin-co-PNPHO solutions were injectable through fine gauge needles and converted to hydrogels in situ at 37 °C in the absence of any crosslinking reagent. By altering PNPHO content, the gelling time of these hydrogels can be finely tuned within the range of 2-15 min to ensure compatibility with surgical requirements. In addition, these hydrogels exhibited compression moduli in the range of 40-145 kPa, which are substantially higher than those of previously developed elastin-based hydrogels. These hydrogels were highly stable in the physiological environment with the evidence of 10 wt% mass loss in 30 days of incubation in a simulated environment. This class of hydrogels is in vivo bioabsorbable due to the gradual increase of the lower critical solution temperature of the copolymer to above 37 °C due to the cleavage of polylactide from

  17. Controlled-surface-wettability-based fabrication of hydrogel substrates with matrix tethering density variations

    Science.gov (United States)

    Rahman, Md. Mahmudur; Lee, Donghee; Bhagirath, Divya; Zhao, Xiangshan; Band, Vimla; Ryu, Sangjin

    2014-03-01

    It is widely accepted that cells behave differently responding to the stiffness of extracellular matrix (ECM). Such observations were made by culturing cells on hydrogel substrates of tunable stiffness. However, it was recently proposed that cells actually sense how strongly they are tethered to ECM, not the local stiffness of ECM. To investigate the hypothesis, we develop constant-stiffness hydrogel substrates with varying matrix tethering density (the number of anchoring sites between the gel and the ECM protein molecules). We fabricate polyacrylamide gel of static stiffness and conjugate ECM proteins to the gel using a cross-linker. When treating the gel with the cross-linker, we control positioning of cross-linker solutions with different concentrations using superhydrophobic barriers on glass, functionalize the gel by pressing it to the aligned cross-linker solutions, and conjugate an ECM protein of constant concentration to the gel. We expect that the gel will be functionalized to different degrees depending on the concentration distribution of the cross-linker and thus the gel will have variations of matrix tethering density even with constant ECM protein concentration. We acknowledge support from Bioengineering for Human Health grant of UNL-UNMC.

  18. RGDS-functionalized polyethylene glycol hydrogel-coated magnetic iron oxide nanoparticles enhance specific intracellular uptake by HeLa cells

    Directory of Open Access Journals (Sweden)

    Nazli C

    2012-04-01

    Full Text Available Caner Nazli1, Tugba Ipek Ergenc2, Yasemin Yar1, Havva Yagci Acar1,3, Seda Kizilel1,21Graduate School of Sciences and Engineering, Koç University, 2Department of Chemical and Biological Engineering, College of Engineering, Koç University, 3Department of Chemistry, Faculty of Arts and Sciences, Koç University, Istanbul, TurkeyAbstract: The objective of this study was to develop thin, biocompatible, and biofunctional hydrogel-coated small-sized nanoparticles that exhibit favorable stability, viability, and specific cellular uptake. This article reports the coating of magnetic iron oxide nanoparticles (MIONPs with covalently cross-linked biofunctional polyethylene glycol (PEG hydrogel. Silanized MIONPs were derivatized with eosin Y, and the covalently cross-linked biofunctional PEG hydrogel coating was achieved via surface-initiated photopolymerization of PEG diacrylate in aqueous solution. The thickness of the PEG hydrogel coating, between 23 and 126 nm, was tuned with laser exposure time. PEG hydrogel-coated MIONPs were further functionalized with the fibronectin-derived arginine-glycine-aspartic acid-serine (RGDS sequence, in order to achieve a biofunctional PEG hydrogel layer around the nanoparticles. RGDS-bound PEG hydrogel-coated MIONPs showed a 17-fold higher uptake by the human cervical cancer HeLa cell line than that of amine-coated MIONPs. This novel method allows for the coating of MIONPs with nano-thin biofunctional hydrogel layers that may prevent undesirable cell and protein adhesion and may allow for cellular uptake in target tissues in a specific manner. These findings indicate that the further biofunctional PEG hydrogel coating of MIONPs is a promising platform for enhanced specific cell targeting in biomedical imaging and cancer therapy.Keywords: PEG hydrogel, surface-initiated photopolymerization, nanoparticle encapsulation, agglomeration

  19. Controlled in situ formation of polyacrylamide hydrogel on PET surface via SI-ARGET-ATRP for wound dressings

    Energy Technology Data Exchange (ETDEWEB)

    Nazari Pour, Sedigheh [Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Ghugare, Shivkumar V. [Department of Textile Science, Faculty of Human Ecology, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Wiens, Richard; Gough, Kathleen [Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Liu, Song, E-mail: Song.Liu@umanitoba.ca [Department of Chemistry, Faculty of Science, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Department of Textile Science, Faculty of Human Ecology, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada); Department of Biosystems Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, Canada R3T 2N2 (Canada)

    2015-09-15

    Graphical abstract: - Highlights: • We grow poly(acrylamide) (PAM) hydrgol from a polymer surface in a controlled way. • Divinyl crosslinker doesn't compromise the control chain growth feature of ARGET-ATRP. • ATR-FTIR-FPA images (spatial resolution 220 nm) reveal a uniform grafting of PAM. • PAM grafted wound dressing can be dual functional: low-adherent and antibacterial. - Abstract: Well-defined polyacrylamide (PAM) hydrogel was synthesized on the surface of poly(ethylene terephthalate) (PET) film via surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). Following the deposition of an ATRP initiator (2-bromoisobutyrylbromide) on PET film, PAM hydrogel was grafted from the functionalized PET surface via ARGET-ATRP. XPS and FTIR-ATR confirmed that PAM hydrogel was successfully grafted on the PET surface. Results from AFM, SEM, and FTIR-FPA microscopic investigations showed that PAM hydrogel uniformly covers the surface of PET film. The grafting yield increases linearly with increasing reaction time, indicating that the growth of PAM hydrogel on the surface of PET is well controlled. In a cell adhesion assay, PAM hydrogel grafted PET films (PAM hydrogel-g-PET) showed low adhesion to keratinocyte cells. To impart PAM hydrogel-g-PET with antibacterial function, AgNPs were self-assembled along the amide side chains of PAM hydrogel. AgNPs loaded-PAM hydrogel-g-PET shows 99% reduction in the number of multidrug-resistant Pseudomonas aeruginosa within 3 h contact.

  20. Controlled in situ formation of polyacrylamide hydrogel on PET surface via SI-ARGET-ATRP for wound dressings

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • We grow poly(acrylamide) (PAM) hydrgol from a polymer surface in a controlled way. • Divinyl crosslinker doesn't compromise the control chain growth feature of ARGET-ATRP. • ATR-FTIR-FPA images (spatial resolution 220 nm) reveal a uniform grafting of PAM. • PAM grafted wound dressing can be dual functional: low-adherent and antibacterial. - Abstract: Well-defined polyacrylamide (PAM) hydrogel was synthesized on the surface of poly(ethylene terephthalate) (PET) film via surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). Following the deposition of an ATRP initiator (2-bromoisobutyrylbromide) on PET film, PAM hydrogel was grafted from the functionalized PET surface via ARGET-ATRP. XPS and FTIR-ATR confirmed that PAM hydrogel was successfully grafted on the PET surface. Results from AFM, SEM, and FTIR-FPA microscopic investigations showed that PAM hydrogel uniformly covers the surface of PET film. The grafting yield increases linearly with increasing reaction time, indicating that the growth of PAM hydrogel on the surface of PET is well controlled. In a cell adhesion assay, PAM hydrogel grafted PET films (PAM hydrogel-g-PET) showed low adhesion to keratinocyte cells. To impart PAM hydrogel-g-PET with antibacterial function, AgNPs were self-assembled along the amide side chains of PAM hydrogel. AgNPs loaded-PAM hydrogel-g-PET shows 99% reduction in the number of multidrug-resistant Pseudomonas aeruginosa within 3 h contact

  1. Poloxamine/fibrin hybrid hydrogels for non-viral gene delivery.

    Science.gov (United States)

    Zhang, Jeremy; Sen, Atanu; Cho, Eunhee; Lee, Jeoung Soo; Webb, Ken

    2014-06-01

    Hydrogels have been widely investigated for localized, sustained gene delivery because of the similarity of their physical properties to native extracellular matrix and their ability to be formed under mild conditions amenable to the incorporation of bioactive molecules. The objective of this study was to develop bioactive hydrogels composed of macromolecules capable of enhancing the efficiency of non-viral vectors. Hybrid hydrogels were prepared by simultaneous enzymatic and Michael-type addition crosslinking of reduced fibrinogen and an acrylated amphiphilic block copolymer, Tetronic T904, in the presence of dithiothreitol (DTT) and thrombin. T904/fibrin hydrogels degraded by surface erosion in the presence of plasmin and provided sustained release of polyplex vectors up to an order of magnitude longer than pure fibrin gel control. In addition, the rate of gel degradation and time-course of polyplex vector release were readily controlled by varying the T904/fibrinogen ratio in the gel composition. When added to transfected neuroblastoma (N2A) cells, both native T904 itself and hydrogel degradation products significantly increased polyplex transfection efficiency with minimal effect on cell viability. To evaluate gel-based transfection, N2A cells encapsulated in small fibrin clusters were covered by or suspended within polyplex-loaded hydrogels. Cells progressively degraded and invaded the hybrid hydrogels, exhibiting increasing gene expression over 2 weeks and then diminishing but persistent gene expression for over 1 month. In conclusion, these results demonstrate that T904/fibrin hybrid hydrogels can be promising tissue engineering scaffolds that provide local, controlled release of non-viral vectors in combination with the generation of bioactive gel degradation products that actively enhance vector efficiency. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24889259

  2. Preparation, characterization, and in vitro enzymatic degradation of chitosan-gelatine hydrogel scaffolds as potential biomaterials.

    Science.gov (United States)

    Gorgieva, Selestina; Kokol, Vanja

    2012-07-01

    The crosslinking of chitosan (CHT) and gelatin (GEL) accomplished with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was investigated and optimized in relation to hydrogels stability by varying the CHT/GEL mass ratio and the EDC/NHS molar ratio at different and constant EDC concentrations. Hydrogels were also fabricated in the presence of α-tocopherol to assess the release mechanism of a lipophilic drug from a highly-hydrophilic CHT/GEL hydrogel network. Alterations in the physico-chemical properties of hydrogels were characterized by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR), and their biostability was studied within a simulated body-fluid solution (PBS of pH 7.4) at 37 °C for 24 h by evaluating the degree of swelling, followed by topography and morphology characterization using scanning electron microscopy (SEM). The analysis confirmed the formation of a modulated hydrogels porosity using different freezing temperatures prior to lyophilization. The in vitro degradation behaviors of the hydrogels were investigated for up to 5 weeks using collagenase, lysozyme, and N-acetyl-β-D-glucosaminidase by monitoring the weight-losses of hydrogels and their degradation products, being identified by UV-Vis spectroscopy and high-performance liquid chromatography (HPLC) as well as the pH monitoring of degraded solutions. It was observed that an inner morphological hydrogel structure influences their swelling and degradation behavior, which is additionally reduced by in-gel-embedded α-tocopherol because of hydrophobic interactions with their constituents, and hindering the effect on collagenase activity. PMID:22447615

  3. Bioresorption mechanisms of chitosan physical hydrogels: A scanning electron microscopy study

    International Nuclear Information System (INIS)

    Tissue-engineered biodegradable medical devices are widely studied and systems must present suitable balance between versatility and elaboration simplicity. In this work, we aim at illustrating that such equilibrium can be found by processing chitosan physical hydrogels without external cross-linker. Chitosan concentration, degree of acetylation, solvent composition, and neutralization route were modulated in order to obtain hydrogels exhibiting different physico-chemical properties. The resulting in vivo biological response was investigated by scanning electron microscopy. “Soft” hydrogels were obtained from chitosan of high degree of acetylation (35%) and by the neutralization with gaseous ammonia of a chitosan acetate aqueous solutions presenting low polymer concentration (Cp = 1.6% w/w). “Harder” hydrogels were obtained from chitosan with lower degree of acetylation (5%) and after neutralization in sodium hydroxide bath (1 M) of hydro-alcoholic chitosan solutions (50/50 w/w water/1,2-propanediol) with a polymer concentration of 2.5% w/w. Soft and hard hydrogels exhibited bioresorption times from below 10 days to higher than 60 days, respectively. We also evidenced that cell colonization and neo-vascularization mechanisms depend on the hydrogel-aggregated structure that is controlled by elaboration conditions and possibly in relation with mechanical properties. Specific processing conditions induced micron-range capillary formation, which can be assimilated to colonization channels, also acting on the resorption scenario. - Highlights: • We elaborated physical chitosan hydrogels presenting tuneable biological properties. • Cell colonization mechanism depends on biological and mechanical hydrogel properties. • Increasing the degree of acetylation will reduce the bioresorption time. • Capillaries played a role of cell colonization pathways

  4. Bioresorption mechanisms of chitosan physical hydrogels: A scanning electron microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Malaise, Sébastien, E-mail: sebastien.malaise@gmail.com [Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Ingénierie des Matériaux Polymères (IMP-UMR 5223), 15 Boulevard Latarjet, 69622 Villeurbanne Cedex (France); Rami, Lila [Université de Bordeaux, Bordeaux 33000 (France); Inserm U1026, Bioingénierie Tissulaire, Bordeaux 33000 (France); Montembault, Alexandra; Alcouffe, Pierre [Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Ingénierie des Matériaux Polymères (IMP-UMR 5223), 15 Boulevard Latarjet, 69622 Villeurbanne Cedex (France); Burdin, Béatrice [Université de Lyon, Université Claude Bernard Lyon 1, Centre Technologique des Microstructure, 69622 Villeurbanne Cedex (France); Bordenave, Laurence [Université de Bordeaux, Bordeaux 33000 (France); Inserm U1026, Bioingénierie Tissulaire, Bordeaux 33000 (France); CHU de Bordeaux, CIC-IT Biomaterials, F-33000 Bordeaux (France); Delmond, Samantha [CHU de Bordeaux, CIC-IT Biomaterials, F-33000 Bordeaux (France); David, Laurent [Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Ingénierie des Matériaux Polymères (IMP-UMR 5223), 15 Boulevard Latarjet, 69622 Villeurbanne Cedex (France)

    2014-09-01

    Tissue-engineered biodegradable medical devices are widely studied and systems must present suitable balance between versatility and elaboration simplicity. In this work, we aim at illustrating that such equilibrium can be found by processing chitosan physical hydrogels without external cross-linker. Chitosan concentration, degree of acetylation, solvent composition, and neutralization route were modulated in order to obtain hydrogels exhibiting different physico-chemical properties. The resulting in vivo biological response was investigated by scanning electron microscopy. “Soft” hydrogels were obtained from chitosan of high degree of acetylation (35%) and by the neutralization with gaseous ammonia of a chitosan acetate aqueous solutions presenting low polymer concentration (Cp = 1.6% w/w). “Harder” hydrogels were obtained from chitosan with lower degree of acetylation (5%) and after neutralization in sodium hydroxide bath (1 M) of hydro-alcoholic chitosan solutions (50/50 w/w water/1,2-propanediol) with a polymer concentration of 2.5% w/w. Soft and hard hydrogels exhibited bioresorption times from below 10 days to higher than 60 days, respectively. We also evidenced that cell colonization and neo-vascularization mechanisms depend on the hydrogel-aggregated structure that is controlled by elaboration conditions and possibly in relation with mechanical properties. Specific processing conditions induced micron-range capillary formation, which can be assimilated to colonization channels, also acting on the resorption scenario. - Highlights: • We elaborated physical chitosan hydrogels presenting tuneable biological properties. • Cell colonization mechanism depends on biological and mechanical hydrogel properties. • Increasing the degree of acetylation will reduce the bioresorption time. • Capillaries played a role of cell colonization pathways.

  5. Synthesis and properties of P(NIPA-co-NVP)-clay hydrogel by radiation polymerization

    International Nuclear Information System (INIS)

    Polymeric hydrogels are unique materials that can absorb and retain large amounts of water. The cross-linking of polymer chain makes them insoluble, soft and elastic. They are stimuli-responsive, displaying phase transitions in response to small changes in temperature, pH, electric field and light. The temperature-sensitive hydrogels have potential applications in gel-based separation processes and in biomedicine, e.g., preparation of drug delivery systems and separation of cells. Thermo-sensitive character of poly (N-isopropylacrylamide) (NIPAm) hydrogels shrinking or swelling below or above lower critical solution temperature (LCST) has widely been investigated in recent years. However, some of their potential applications are hindered by their low mechanical strength, low swelling ratio, bad biocompatibility and low purity, owing to the use of catalysts or additives in chemosynthesis. Liang synthesized clay/PNIPAm composite hydrogel to improve its mechanical strength. In this work, hydrogels of P (NIPA-co-NVP)-Clay were synthesized by 60Co γ-ray irradiation. Different thermo-sensitive hydrogels were made under different experimental conditions such as dose, dose rate, monomer concentration, monomer ratio and content of clay. X-ray diffraction shows that the layer distance of Na-clay is changed from 1.6nm to 2.7nm because Na-clay pieces can be intercalated or exfoliated by HTMAB, and P(NIPA-co-NVP) -clay pieces is 3.4nm. The swelling property tests show that the LCST of PNIPA is 32 degree C, the LCST of P(NIPA-co-NVP) is higher than PNIPA. With the increase of NVP content, LCST is higher. As the ratio of NIPA/NVP is 95/5, hydrogel shows the best swelling property and LCST is 37 degree C. LCST of P(NIPA-co-NVP)-clay Hydrogel is not changed, but the strength and swelling properties are better. (authors)

  6. Poly(ethylene glycol) methacrylate/dimethacrylate hydrogels for controlled release of hydrophobic drugs.

    Science.gov (United States)

    Diramio, Jackie A; Kisaalita, William S; Majetich, George F; Shimkus, Joel M

    2005-01-01

    Hydrogels have been successfully used to entrap hydrophilic drugs and release them in a controlled fashion; however, the entrapment and release of hydrophobic drugs has not been well studied. We report on the release characteristics of a model hydrophobic drug, the steroid hormone estradiol, entrapped in low (MW 360/MW 550) and high (MW 526/MW 1000) molecular weight poly(ethylene glycol) methacrylate (PEG-MA)/dimethacrylate (PEG-DMA) hydrogels. The cross-linking ratio, temperature, and pH ranged from 10:1 to 10:3, from 33 to 41 degrees C, and from 2 to 12, respectively. The gelation of the PEG-MA/PEG-DMA hydrogel was initiated with UV irradiation. The absence of poly(glutamic acid) in the hydrogel formulation resulted in a loss of pH sensitivity in the acidic range, which was displayed by the hydrogels' similarities in swelling ratios in the pH buffers of pH 2, 4, and 7. Use of high molecular weight polymers resulted in a higher hydrogel swelling (300%) in comparison to the low molecular weight polymers. Drug size was found to be a significant factor. In comparison to 100% estradiol (MW 272) release, the fractional release of insulin (MW 5733) was 12 and 24% in low and high molecular weight gels at pH 2, respectively, and 17% in low molecular weight gels at pH 7. On the release kinetics of the estradiol drug, the hydrogels displayed a non-Fickian diffusion mechanism, which indicated that the media penetration rate is in the same range as the drug diffusion. The synthesis, entrapment, and release of estradiol by the PEG-MA/PEG-DMA hydrogels proved to be successful, but the use of ethanol in the buffers to promote the hydrophobic release of the estradiol in the in vitro environment caused complications, attributed to the process of transesterification. PMID:16080712

  7. Preparation of wound dressing of polyvinyl alcohol/silk fibroin hydrogels by gamma radiation

    International Nuclear Information System (INIS)

    Poly vinylalcohol/silk fibroin (PVA/SF) hydrogels were prepared by γ-radiation. The preparation conditions such as absorbed doses and PVA/SF concentrations were investigated. When exposed to γ -radiation, PVA/SF was crosslinked to yield high water absorption materials with water content of 100 - 1000% of their dried weight depending on the preparation conditions. The crosslinked density seems to be the main factor governing the swelling of these gels. The swelling behaviors in NaCl aqueous solutions were also investigated. The swelling of PVA/SF hydrogels decreases when exposed to electrolyte solution. With an increase of absorbed dose, the gel fraction of PVA/SF increases

  8. Synthesis of poly (acrymide-CO-metacrylic acid) hydrogels by means of gamma

    International Nuclear Information System (INIS)

    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.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

  9. Synthesis and characterization of carboxymethyl chitosan hydrogel: Application as site specific delivery for lercanidipine hydrochloride

    Indian Academy of Sciences (India)

    Subhash S Vaghani; Madhabhai M Patel; C S Satish; Kandarp M Patel; N P Jivani

    2012-12-01

    In the present study, carboxymethylchitosan (CMCS) was prepared from chitosan, crosslinked with glutaraldehyde and evaluated in vitro as a potential carrier for site specific drug delivery of lercanidipine hydrochloride (LERH). LERH was incorporated at the time of crosslinking of CMCS. The chitosan was evaluated for its degree of deacetylation () and average molecular weight, which were found to be 84.6% and 3.5 × 104 Da, respectively. The degree of substitution on prepared CMCS was found to be 0.68. All hydrogel formulations showed more than 86% and 77% yield and drug loading, respectively. The swelling behaviour of prepared hydrogels were checked in different pH values, 1.2, 6.8 and 7.4, indicated pH responsive swelling characteristic with very less swelling at pH 1.2 and quick swelling at pH 6.8 followed by linear swelling at pH 7.4 with slight increase. In vitro release profile was carried out at the same conditions as in swelling and drug release was found to be dependent on swelling of hydrogels and showed biphasic release pattern with non-fickian diffusion kinetics at higher pH. The carboxymethylation of chitosan, entrapment of drug and its interaction in prepared hydrogels were checked by FTIR, 1H-NMR, DSC and -XRD studies, which confirmed formation of CMCS from chitosan and absence of any significant chemical change in LERH after being entrapped in crosslinked hydrogel formulations. The surface morphology of formulation 6 was checked before and after dissolution, revealed open channel like pores formation after dissolution.

  10. New hydrogels based on maleilated collagen with potential applications in tissue engineering

    International Nuclear Information System (INIS)

    New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of overcoming the high degradation rate displayed by collagen that is not otherwise chemically crosslinked. Semi-interpenetrated matrices were obtained by free radical polymerization of maleilated collagen (CM) and 2-hydroxyethyl methacrylate (HEMA) in the presence of ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) as initiating system. The resulting matrices (CMH) had a sharp decrease in degradation, when compared to pure collagen. FTIR and H1 NMR spectroscopies were used to confirm the incorporation of MA on the collagen peptide chains. The final composition of CMH was found to be strongly dependent by the concentration of maleilated collagen. The morphology of the hydrogels was studied by Scanning electron microscopy (SEM) and the macro-gel structure was confirmed. Water uptake of the synthetised hydrogels is influenced by both composition and the porosity of the matrices.

  11. Tragacanth gum/nano silver hydrogel on cotton fabric: In-situ synthesis and antibacterial properties.

    Science.gov (United States)

    Montazer, M; Keshvari, A; Kahali, P

    2016-12-10

    This paper is mainly focused on introducing cotton fabric with hydrogel and antimicrobial properties using Tragacanth gum as a natural polymer with hydrogel properties, silver nitrate as silver precursor, citric acid as a cross-linking agent and sodium hypophosphite as catalyst. The water absorption behavior of the treated fabrics was investigated with moisture regain, water retention, drying time of wetted fabric at room condition and vertical wicking tests. Antibacterial properties of the samples were evaluated against Escherichia coli and Staphylococcous aureus. The SEM pictures confirmed formation of nano silver and hydrogel layer on the fabric surface and XRD performed the crystal and particle size of the nano silver. The chemical structure of the fabric samples was identified with FTIR spectra. The central composite design (CCD) was used for statistical modelling, evaluated effective parameters and created optimum conditions. The treated cotton fabrics showed good water absorption properties along with reasonable antibacterial effectiveness. PMID:27577917

  12. Improving the performance of electrochemical microsensors based on enzymes entrapped in a redox hydrogel

    International Nuclear Information System (INIS)

    Microsensors based on carbon fiber microelectrodes coated with enzyme-entrapping redox hydrogels facilitate the in vivo detection of substances of interest within the central nervous system, including hydrogen peroxide, glucose, choline and glutamate. The hydrogel, formed by cross-linking a redox polymer, entraps the enzymes and mediates electron transfer between the enzymes and the electrode. It is important that the enzymes are entrapped in their enzymatically active state. Should entrapment cause enzyme denaturation, the sensitivity and the selectivity of the sensor may be compromised. Synthesis of the redox polymer according to published procedures may yield a product that precipitates when added to aqueous enzyme solutions. Casting hydrogels from solutions that contain the precipitate produces microsensors with low sensitivity and selectivity, suggesting that the precipitation disrupts the structure of the enzymes. Herein, we show that a surfactant, sodium dodecyl sulfate (SDS), can prevent the precipitation and improve the sensitivity and selectivity of the sensors

  13. New hydrogels based on maleilated collagen with potential applications in tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Potorac, Simona; Popa, Marcel [' Gheorghe Asachi' Technical University, Faculty of Chemical Engineering and Environmental Protection, Department of Natural and Synthetic Polymers, 71 Dimitrie Mangeron, 700050 Iasi (Romania); Maier, Vasilica [' Gheorghe Asachi' Technical University, Faculty of Textile, Leather and Industrial Management, Department of Chemical Technology of Leather and Substitutes, 71 Dimitrie Mangeron, 700050, Iasi (Romania); Lisa, Gabriela [' Gheorghe Asachi' Technical University, Faculty of Chemical Engineering and Environmental Protection, Department of Natural and Synthetic Polymers, 71 Dimitrie Mangeron, 700050 Iasi (Romania); Verestiuc, Liliana, E-mail: liliana.verestiuc@bioinginerie.ro [' Gr.T.Popa' University of Medicine and Pharmacy, Faculty of Medical Bioengineering, Department of Biological Sciences, 9-13 Kogalniceanu Street, 700454, Iasi (Romania)

    2012-02-01

    New hydrogels based on maleic anhydride (MA) modified collagen were prepared with the aim of overcoming the high degradation rate displayed by collagen that is not otherwise chemically crosslinked. Semi-interpenetrated matrices were obtained by free radical polymerization of maleilated collagen (CM) and 2-hydroxyethyl methacrylate (HEMA) in the presence of ammonium persulfate (APS) and N,N,N Prime ,N Prime -tetramethylethylenediamine (TEMED) as initiating system. The resulting matrices (CMH) had a sharp decrease in degradation, when compared to pure collagen. FTIR and H{sup 1} NMR spectroscopies were used to confirm the incorporation of MA on the collagen peptide chains. The final composition of CMH was found to be strongly dependent by the concentration of maleilated collagen. The morphology of the hydrogels was studied by Scanning electron microscopy (SEM) and the macro-gel structure was confirmed. Water uptake of the synthetised hydrogels is influenced by both composition and the porosity of the matrices.

  14. Preparation of konjac glucomannan hydrogels as DNA-controlled release matrix.

    Science.gov (United States)

    Wen, Xian; Wang, Ting; Wang, Zhiyong; Li, Li; Zhao, Changsheng

    2008-04-01

    In this study, hydrogels for DNA-controlled release was prepared with konjac glucomannan (KGM), a water-soluble non-ionic polysaccharide, by means of deacetylated reaction and physically cross-linking method under mild conditions. The properties of the KGM hydrogels were analyzed by FTIR spectra and scanning electron microscopy (SEM). The integrality of the released DNA was investigated by circular dichroism (CD). The DNA release kinetics was performed using the DNA-loaded KGM gels in buffer solutions of pH 7.4 at 37+/-0.5 degrees C. Peppas model and Higuchi model were used to analysis the DNA release mechanism; the data indicated that the DNA release can be controlled by changing the preparation conditions and the structure parameters of the gels. This study suggested that the KGM hydrogels have a potential use for advanced controlled release. PMID:18190958

  15. Xanthan/chondroitin sulfate hydrogels as carrier for drug delivery applications

    Directory of Open Access Journals (Sweden)

    Ana-Maria Oprea

    2010-06-01

    Full Text Available Preparation, characterization and in vitro release studies of codeine from xanthan/chondroitin sulfate (X/CS hydrogels prepared through a crosslinking technique are reported. Swelling and drug delivery studies were conducted in phosphate buffer solution (pH=7.4 which simulates the pH of the intestinal fluid, at 37 °C. The in vitro release test revealed that the percentage of codeine released in phosphate buffer solution increases with increasing the amount of chondroitin sulfate in the composition of hydrogels. The drug release behaviour of the hydrogels loaded with codeine fitted well with case II transport mechanism for all formulations. The biocompatibility testing was made by hemolisys (plasma hemoglobin technique.

  16. Thermoresponsive and bioactive poly(vinyl ether)-based hydrogels synthesized by radiation copolymerization and photochemical immobilization

    International Nuclear Information System (INIS)

    A thermoresponsive hydrogel was synthesized by radiation copolymerization of ethylene glycol vinyl ether (EGVE) and butyl vinyl ether (BVE) in the presence of cross-linking agent diethylene glycol divinyl ether. The gel was modified by a cell adhesion factor RGD by photochemical immobilization technique. While the unmodified hydrogel shows fully hydrated form at low temperatures (+4 oC) and it extensively dehydrates at 37 oC, the biomodified hydrogel still kept its thermoresponsive character after immobilization. The effectiveness of immobilization was checked with FTIR-ATR and XPS. The use of bioactive thermoresponsive hydrogels in cell culture applications was investigated. For this purpose, cell culture experiments were realized by L929 mouse fibroblasts. Cell attachment experiments revealed the effect of immobilized RGD with higher values of cell attachment (∼85%), which were obtained especially in the absence of serum. The thermoresponsive character of the hydrogel was useful for the application of low-temperature treatment in order to recover the attached viable cells from the surface of the hydrogel without using trypsin. When the culture temperature was decreased from 37 to 10 deg. C for 30 min ∼80% of the cells were detached from the hydrogel surface

  17. Integrating valve-inspired design features into poly(ethylene glycol) hydrogel scaffolds for heart valve tissue engineering.

    Science.gov (United States)

    Zhang, Xing; Xu, Bin; Puperi, Daniel S; Yonezawa, Aline L; Wu, Yan; Tseng, Hubert; Cuchiara, Maude L; West, Jennifer L; Grande-Allen, K Jane

    2015-03-01

    The development of advanced scaffolds that recapitulate the anisotropic mechanical behavior and biological functions of the extracellular matrix in leaflets would be transformative for heart valve tissue engineering. In this study, anisotropic mechanical properties were established in poly(ethylene glycol) (PEG) hydrogels by crosslinking stripes of 3.4 kDa PEG diacrylate (PEGDA) within 20 kDa PEGDA base hydrogels using a photolithographic patterning method. Varying the stripe width and spacing resulted in a tensile elastic modulus parallel to the stripes that was 4.1-6.8 times greater than that in the perpendicular direction, comparable to the degree of anisotropy between the circumferential and radial orientations in native valve leaflets. Biomimetic PEG-peptide hydrogels were prepared by tethering the cell-adhesive peptide RGDS and incorporating the collagenase-degradable peptide PQ (GGGPQG↓IWGQGK) into the polymer network. The specific amounts of RGDS and PEG-PQ within the resulting hydrogels influenced the elongation, de novo extracellular matrix deposition and hydrogel degradation behavior of encapsulated valvular interstitial cells (VICs). In addition, the morphology and activation of VICs grown atop PEG hydrogels could be modulated by controlling the concentration or micro-patterning profile of PEG-RGDS. These results are promising for the fabrication of PEG-based hydrogels using anatomically and biologically inspired scaffold design features for heart valve tissue engineering. PMID:25433168

  18. Facile synthesis of glucose-sensitive chitosan-poly(vinyl alcohol) hydrogel: Drug release optimization and swelling properties.

    Science.gov (United States)

    Abureesh, Mosab Ali; Oladipo, Akeem Adeyemi; Gazi, Mustafa

    2016-09-01

    The study describes the development of glucose-sensitive hydrogel and optimization of bovine serum albumin release profile from the hydrogel. To enhance the glucose sensitivity and improve the swelling behaviors of the hydrogel system, boric acid crosslinking, and freeze-thawing cycle techniques were used to prepare chitosan-poly(vinyl alcohol) hydrogel. The structure of the resultant hydrogel was confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. The experimental results revealed that the swelling of the hydrogel was influenced by the pH of the medium, and the hydrogel displayed explicit glucose-sensitivity under physiological conditions. The values of the diffusion exponent range between 0.34 and 0.44 and the diffusion of water into the gel system are assumed to be pseudo-Fickian in nature. Under optimized conditions, the cumulative Bovine serum albumin (BSA) drug releases ranged between 69.33±1.95% and 86.45±1.16% at 37°C in the presence of glucose and pH 7.4, respectively. PMID:26459171

  19. Resilin-like polypeptide-poly(ethylene gylcol) hybrid hydrogels for mechanically-demanding tissue engineering applications

    Science.gov (United States)

    McGann, Christopher Leland

    Technological progress in the life sciences and engineering has combined with important insights in the fields of biology and material science to make possible the development of biological substitutes which aim to restore function to damaged tissue. Numerous biomimetic hydrogels have been developed with the purpose of harnessing the regenerative capacity of cells and tissue through the rational deployment of biological signals. Aided by recombinant DNA technology and protein engineering methods, a new class of hydrogel precursor, the biosynthetic protein polymer, has demonstrated great promise towards the development of highly functional tissue engineering materials. In particular, protein polymers based upon resilin, a natural protein elastomer, have demonstrated outstanding mechanical properties that would have great value in soft tissue applications. This dissertation introduces hybrid hydrogels composed of recombinant resilin-like polypeptides (RLPs) cross-linked with multi-arm PEG macromers. Two different chemical strategies were employed to form RLP-PEG hydrogels: one utilized a Michael-type addition reaction between the thiols of cysteine residues present within the RLP and vinyl sulfone moieties functionalized on a multi-arm PEG macromer; the second system cross-links a norbornene-functionalized RLP with a thiol-functionalized multi-arm PEG macromer via a photoinitiated thiol-ene step polymerization. Oscillatory rheology and tensile testing confirmed the formation of elastic, resilient hydrogels in the RLP-PEG system cross-linked via Michael-type addition. These hydrogels supported the encapsulation and culture of both human aortic adventitial fibroblasts and human mesenchymal stem cells. Additionally, these RLP-PEG hydrogels exhibited phase separation behavior during cross-linking that led to the formation of a heterogeneous microstructure. Degradation could be triggered through incubation with matrix metalloproteinase. Photocross-linking was conferred to

  20. Effect of particle size and charge on the network properties of microsphere-based hydrogels

    OpenAIRE

    van Tomme, S.R.; van Nostrum, C.F.; Dijkstra, M.; de Smedt, S.C.; Hennink, W.E.

    2008-01-01

    This work describes the tailorability of the network properties of self-assembling hydrogels, based on ionic crosslinking between dextran microspheres. Copolymerization of hydroxyethyl methacrylate-derivatized dextran (dex-HEMA), emulsified in an aqueous poly(ethylene glycol) (PEG) solution, with methacrylic acid (MAA) or dimethylaminoethyl methacrylate (DMAEMA) resulted in negatively or positively charged microspheres, respectively, at physiological pH. The monomer/HEMA ratio ranged between ...

  1. Immobilizing Enzymes onto Electrode Arrays by Hydrogel Photolithography to Fabricate Multi-Analyte Electrochemical Biosensors

    OpenAIRE

    Yan, Jun; Pedrosa, Valber A.; Simonian, Aleksandr L.; Revzin, Alexander

    2010-01-01

    This paper describes a biomaterial microfabrication approach for interfacing functional biomolecules (enzymes) with electrode arrays. Poly (ethylene glycol) (PEG) hydrogel photopatterning was employed to integrate gold electrode arrays with enzymes - glucose oxidase (GOX) and lactate oxidase (LOX). In this process, PEG diacrylate (DA)-based prepolymer containing enzyme molecules as well as redox species (vinylferrocene) was spin-coated, registered and UV cross-linked on top of an array of gol...

  2. Fabrication of chitosan/polyacrylonitrile blend and semi-IPN hydrogel with epichlorohydrin

    Energy Technology Data Exchange (ETDEWEB)

    Aijaz, Muhammad Omer; Haider, Sajjad, E-mail: shaider@ksu.edu.sa; Al Mubddel, Fahad S.; Al Masry, Waheed A. [Department of Chemical Engineering, College of Engineering, King Saud University, P.O BOX 800, Riyadh 11421, KSA (Saudi Arabia)

    2015-05-22

    The present study is focused on the preparation of chitosan (CS)/polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). Blend CS/PAN hydrogel films (HFs) were prepared by solution blending and casting technique. CS in the blend was crosslinked with epichlorohydrin (ECH) to prepare sIPN. The developed CS/PAN blend and sIPN hydrogels were characterized with Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), Thermagravimetric analysis (TGA), and Differential Scanning Calorimeter (DSC). The result showed good miscibility between CS and PAN and crosslinking of CS in the blend. The swelling of the different blended and sIPN hydrogels samples were examined at room temperature (T{sub r}). Blend (C80/P20) sample showed highest swelling (∼2400%) and fair degree of stability (∼28% until 96 h), whereas sIPN hydrogel exhibited relatively low degree of swelling (∼244%) and high degree of aqueous (∼85 % until 96 h), and thermal (onset temperature 304°C) stabilities.

  3. Radiation stability of resveratrol in immobilization on poly vinyl pyrrolidone hydrogel dressing for dermatological use

    Science.gov (United States)

    Momesso, Roberta G. R. A. P.; Moreno, Carolina S.; Rogero, Sizue O.; Rogero, José R.; Spencer, Patrick J.; Lugão, Ademar B.

    2010-03-01

    The polyphenol trans-resveratrol is a natural phytoalexin, which is found in red wine and in a wide variety of plant species. Resveratrol displays a wide array of biological activities, such as modulation of lipid metabolism, anti-inflammatory and antioxidant activities. This active compound immobilized in polyvinylpyrrolidone (PVP) hydrogel could be very interesting for topical administration, as a dressing form for dermatological use. However, PVP hydrogel obtained by radiation-induced crosslinking can cause undesirable hydrolysis reactions in the active compound. The aim of this work was to verify the resveratrol stability after irradiation at 0.5 and 1 kGy in the presence of ethanol, methanol or tert-butyl alcohol. The integrity of these samples was compared to unirradiated resveratrol by HPLC. The PVP hydrogel matrix was characterized by gel fraction, swelling and in vitro biocompatibility test. The results of gel fraction and swelling degree were approximately 90% and 1600%, respectively. The cytotoxicity assay showed absence of toxicity for this formulation after crosslinking and sterilization, indicating that the PVP hydrogel formulation was appropriate for resveratrol immobilization to produce a dressing for dermatological use.

  4. In vitro apatite-forming ability of hydrogels derived from sodium carboxymethylcellulose

    International Nuclear Information System (INIS)

    Hydrogels able to form a bone-like hydroxyapatite (HAp) layer in the body environment are attractive materials as scaffolds for tissue engineering because they show osteoconductivity, i.e. bone-bonding property. In the present study, we synthesized hydrogels from sodium carboxymethylcellulose (sCMC), a water soluble polymer, through modification with a cross-linking agent, either ethylenediamine (EDA) or 3-aminopropyltriethoxysilane (APTES), followed by treatment with an aqueous solution containing calcium chloride aqueous solution. Formation of the bone-like HAp on the hydrogels was evaluated after immersion in a simulated body fluid (SBF). Hydrogels modified with the cross-linking agents EDA or APTES, and treated with 0.1 mol/dm3 of calcium chloride aqueous solution, formed a bone-like HAp layer on their surfaces after immersion in SBF for 3 days. Modification of organic polymers rich in carboxyl groups with APTES and CaCl2 offers a new method to produce biomaterials with greater potential for forming HAp, which provides high affinity to living bone because the incorporation of silanol groups confers the high ability to induce HAp formation.

  5. In vitro apatite-forming ability of hydrogels derived from sodium carboxymethylcellulose

    Energy Technology Data Exchange (ETDEWEB)

    Koh, M-Y; Ohtsuki, C [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Morita, Y; Miyazaki, T, E-mail: koh.miyoung@h.mbox.nagoya-u.ac.jp [Graduate School of Life Science and System Engineering, Kyusyu Institute of Technology, 2-4, Hibikino, Wakamatsu-ku, Kitakyusyu 808-0196 (Japan)

    2011-10-29

    Hydrogels able to form a bone-like hydroxyapatite (HAp) layer in the body environment are attractive materials as scaffolds for tissue engineering because they show osteoconductivity, i.e. bone-bonding property. In the present study, we synthesized hydrogels from sodium carboxymethylcellulose (sCMC), a water soluble polymer, through modification with a cross-linking agent, either ethylenediamine (EDA) or 3-aminopropyltriethoxysilane (APTES), followed by treatment with an aqueous solution containing calcium chloride aqueous solution. Formation of the bone-like HAp on the hydrogels was evaluated after immersion in a simulated body fluid (SBF). Hydrogels modified with the cross-linking agents EDA or APTES, and treated with 0.1 mol/dm{sup 3} of calcium chloride aqueous solution, formed a bone-like HAp layer on their surfaces after immersion in SBF for 3 days. Modification of organic polymers rich in carboxyl groups with APTES and CaCl{sub 2} offers a new method to produce biomaterials with greater potential for forming HAp, which provides high affinity to living bone because the incorporation of silanol groups confers the high ability to induce HAp formation.

  6. In vitro apatite-forming ability of hydrogels derived from sodium carboxymethylcellulose

    Science.gov (United States)

    Koh, M.-Y.; Morita, Y.; Miyazaki, T.; Ohtsuki, C.

    2011-10-01

    Hydrogels able to form a bone-like hydroxyapatite (HAp) layer in the body environment are attractive materials as scaffolds for tissue engineering because they show osteoconductivity, i.e. bone-bonding property. In the present study, we synthesized hydrogels from sodium carboxymethylcellulose (sCMC), a water soluble polymer, through modification with a cross-linking agent, either ethylenediamine (EDA) or 3-aminopropyltriethoxysilane (APTES), followed by treatment with an aqueous solution containing calcium chloride aqueous solution. Formation of the bone-like HAp on the hydrogels was evaluated after immersion in a simulated body fluid (SBF). Hydrogels modified with the cross-linking agents EDA or APTES, and treated with 0.1 mol/dm3 of calcium chloride aqueous solution, formed a bone-like HAp layer on their surfaces after immersion in SBF for 3 days. Modification of organic polymers rich in carboxyl groups with APTES and CaCl2 offers a new method to produce biomaterials with greater potential for forming HAp, which provides high affinity to living bone because the incorporation of silanol groups confers the high ability to induce HAp formation.

  7. Radiation stability of resveratrol in immobilization on poly vinyl pyrrolidone hydrogel dressing for dermatological use

    International Nuclear Information System (INIS)

    The polyphenol trans-resveratrol is a natural phytoalexin, which is found in red wine and in a wide variety of plant species. Resveratrol displays a wide array of biological activities, such as modulation of lipid metabolism, anti-inflammatory and antioxidant activities. This active compound immobilized in polyvinylpyrrolidone (PVP) hydrogel could be very interesting for topical administration, as a dressing form for dermatological use. However, PVP hydrogel obtained by radiation-induced crosslinking can cause undesirable hydrolysis reactions in the active compound. The aim of this work was to verify the resveratrol stability after irradiation at 0.5 and 1 kGy in the presence of ethanol, methanol or tert-butyl alcohol. The integrity of these samples was compared to unirradiated resveratrol by HPLC. The PVP hydrogel matrix was characterized by gel fraction, swelling and in vitro biocompatibility test. The results of gel fraction and swelling degree were approximately 90% and 1600%, respectively. The cytotoxicity assay showed absence of toxicity for this formulation after crosslinking and sterilization, indicating that the PVP hydrogel formulation was appropriate for resveratrol immobilization to produce a dressing for dermatological use.

  8. Fabrication of chitosan/polyacrylonitrile blend and semi-IPN hydrogel with epichlorohydrin

    Science.gov (United States)

    Aijaz, Muhammad Omer; Haider, Sajjad; Al Mubddel, Fahad S.; Al Masry, Waheed. A.

    2015-05-01

    The present study is focused on the preparation of chitosan (CS)/polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). Blend CS/PAN hydrogel films (HFs) were prepared by solution blending and casting technique. CS in the blend was crosslinked with epichlorohydrin (ECH) to prepare sIPN. The developed CS/PAN blend and sIPN hydrogels were characterized with Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), Thermagravimetric analysis (TGA), and Differential Scanning Calorimeter (DSC). The result showed good miscibility between CS and PAN and crosslinking of CS in the blend. The swelling of the different blended and sIPN hydrogels samples were examined at room temperature (Tr). Blend (C80/P20) sample showed highest swelling (˜2400%) and fair degree of stability (˜28% until 96 h), whereas sIPN hydrogel exhibited relatively low degree of swelling (˜244%) and high degree of aqueous (˜85 % until 96 h), and thermal (onset temperature 304°C) stabilities

  9. Evaluation of Gelatin Microparticles as Adherent-Substrates for Mesenchymal Stem Cells in a Hydrogel Composite.

    Science.gov (United States)

    Lu, Steven; Lee, Esther J; Lam, Johnny; Tabata, Yasuhiko; Mikos, Antonios G

    2016-06-01

    Due to the lack of cell-adhesive moieties in traditional synthetic hydrogels, the present work investigated the use of degradable gelatin microparticles (GMPs) as temporary adherent substrates for anchorage-dependent mesenchymal stem cells (MSCs). MSCs were seeded onto GMPs of varying crosslinking densities and sizes to investigate their role on influencing MSC differentiation and aggregation. The MSC-seeded GMPs were then encapsulated in poly(ethylene glycol)-based hydrogels and cultured in serum-free, growth factor-free osteochondral medium. Non-seeded MSCs co-encapsulated with GMPs in the hydrogels were used as a control for comparison. Over the course of 35 days, MSCs seeded on GMPs exhibited more cell-cell contacts, greater chondrogenic potential, and a down-regulation of osteogenic markers compared to the controls. Although the factors of GMP crosslinking and size had nominal influence on MSC differentiation and aggregation, GMPs demonstrate potential as an adherent-substrate for improving cell delivery from hydrogel scaffolds by facilitating cell-cell contacts and improving MSC differentiation. PMID:26935924

  10. Radiation stability of resveratrol in immobilization on poly vinyl pyrrolidone hydrogel dressing for dermatological use

    Energy Technology Data Exchange (ETDEWEB)

    Momesso, Roberta G.R.A.P., E-mail: robertapassarelli@yahoo.com.b [IPEN/CNEN-SP-Instituto de Pesquisas Energeticas e Nucleares, Avenida Professor Lineu Prestes, 2242, Cidade Universitaria, Sao Paulo, SP, CEP 05508-000 (Brazil); Moreno, Carolina S.; Rogero, Sizue O.; Rogero, Jose R.; Spencer, Patrick J.; Lugao, Ademar B. [IPEN/CNEN-SP-Instituto de Pesquisas Energeticas e Nucleares, Avenida Professor Lineu Prestes, 2242, Cidade Universitaria, Sao Paulo, SP, CEP 05508-000 (Brazil)

    2010-03-15

    The polyphenol trans-resveratrol is a natural phytoalexin, which is found in red wine and in a wide variety of plant species. Resveratrol displays a wide array of biological activities, such as modulation of lipid metabolism, anti-inflammatory and antioxidant activities. This active compound immobilized in polyvinylpyrrolidone (PVP) hydrogel could be very interesting for topical administration, as a dressing form for dermatological use. However, PVP hydrogel obtained by radiation-induced crosslinking can cause undesirable hydrolysis reactions in the active compound. The aim of this work was to verify the resveratrol stability after irradiation at 0.5 and 1 kGy in the presence of ethanol, methanol or tert-butyl alcohol. The integrity of these samples was compared to unirradiated resveratrol by HPLC. The PVP hydrogel matrix was characterized by gel fraction, swelling and in vitro biocompatibility test. The results of gel fraction and swelling degree were approximately 90% and 1600%, respectively. The cytotoxicity assay showed absence of toxicity for this formulation after crosslinking and sterilization, indicating that the PVP hydrogel formulation was appropriate for resveratrol immobilization to produce a dressing for dermatological use.

  11. Synthesis of Thermal Polymerizable Alginate-GMA Hydrogel for Cell Encapsulation

    Directory of Open Access Journals (Sweden)

    Xiaokun Wang

    2015-01-01

    Full Text Available Alginate is a negative ionic polysaccharide that is found abundantly in nature. Calcium is usually used as a cross-linker for alginate. However, calcium cross-linked alginate is used only for in vitro culture. In the present work, alginate was modified with glycidyl methacrylate (GMA to produce a thermal polymerizable alginate-GMA (AA-GMA macromonomer. The molecular structure and methacrylation (%DM of the macromonomer were determined by 1H NMR. After mixing with the correct amount of initiator, the AA-GMA aqueous solution can be polymerized at physiological temperature. The AA-GMA hydrogels exhibited a three-dimensional porous structure with an average pore size ranging from 50 to 200 μm, directly depending on the macromonomer concentration. Biocompatibility of the AA-GMA hydrogel was determined by in vivo muscle injection and cell encapsulation. Muscle injection in vivo showed that the AA-GMA solution mixed with initiator could form a hydrogel in situ and had a mild inflammatory effect. Human umbilical vein endothelial cells (HUVECs were encapsulated in the AA-GMA hydrogels in situ at 37°C. Cell viability and proliferation were unaffected by macromonomer concentrations, which suggests that AA-GMA has a potential application in the field of tissue engineering, especially for myocardial repair.

  12. The effect of calcium chloride concentration on alginate/Fmoc-diphenylalanine hydrogel networks.

    Science.gov (United States)

    Çelik, Ekin; Bayram, Cem; Akçapınar, Rümeysa; Türk, Mustafa; Denkbaş, Emir Baki

    2016-09-01

    Peptide based hydrogels gained a vast interest in the tissue engineering studies thanks to great superiorities such as biocompatibility, supramolecular organization without any need of additional crosslinker, injectability and tunable nature. Fmoc-diphenylalanine (FmocFF) is one of the earliest and widely used example of these small molecule gelators that have been utilized in biomedical studies. However, Fmoc-peptides are not feasible for long term use due to low stability and weak mechanical properties at neutral pH. In this study, Fmoc-FF dipeptides were mechanically enhanced by incorporation of alginate, a biocompatible and absorbable polysaccharide. The binary hydrogel is obtained via molecular self-assembly of FmocFF dipeptide in alginate solution followed by ionic crosslinking of alginate moieties with varying concentrations of calcium chloride. Hydrogel characterization was evaluated in terms of morphology, viscoelastic moduli and diffusional phenomena and the structures were tested as 3D scaffolds for bovine chondrocytes. In vitro evaluation of scaffolds lasted up to 14days and cell viability, sulphated glycosaminoglycan (sGAG) levels, collagen type II synthesis were determined. Our results showed that alginate incorporation into FmocFF hydrogels leads to better mechanical properties and higher stability with good biocompatibility. PMID:27207058

  13. Vitamin C hinders radiation cross-linking in aqueous poly(vinyl alcohol) solutions

    International Nuclear Information System (INIS)

    Poly(vinyl alcohol) (PVA) is a promising semi-crystalline material for biomedical applications. It is soluble in water and can be formed into hydrogels by freezing and thawing or crystallizing from an aqueous theta solution such as that of polyethylene glycol (PEG). Radiation cross-linking caused by sterilization or high dose irradiation of concentrated PVA solutions could compromise some properties of these hydrogels. Therefore, we hypothesized that radiation cross-linking of PVA solutions and PVA-PEG theta gels could be prevented by using the antioxidant vitamin C as an anticross-linking agent. Our hypothesis tested positive. Vitamin C concentrations of 0.75 and 4.5 mol/mol of PVA repeating unit could prevent cross-linking in 17.5 wt/v% PVA solutions made with PVA molecular weight of 115,000 g/mol irradiated to 25 and 100 kGy, respectively. Vitamin C also prevented cross-linking in 25 kGy irradiated PVA-PEG theta gels containing up to 5 wt% PEG and decreased the viscosity of those up to 39 wt%

  14. MESO-STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhong Yang; Jian-hua Rong; Dan Li

    2003-01-01

    Meso-structured (opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods: post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers. A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color, which is important in designing tunable photonic crystals. Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed. The catalytic effect of acid groups inthe templates was emphasized for a preferential formation of TiO2 in the region containing acid groups, which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  15. MESO—STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhongYang; Jian-huaRong; DanLi

    2003-01-01

    Meso-structured(opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods:post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers.A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color,which is important in designing tunable photonic crystals.Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed.The catalytic effect of acid groups in the templates was emphasized for a preferential formation of TiO2 in the region containing acid groups,which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  16. Immobilization and release study of a red alga extract in hydrogel membranes

    International Nuclear Information System (INIS)

    In pharmaceutical technology hydrogel is the most used among the polymeric matrices due to its wide application and functionality, primarily in drug delivery system. In view of the large advance innovations in cosmetic products, both through the introduction of new active agents as the matrices used for its controlled release, the objective of this study was to evaluate the release and immobilization of a natural active agent, the Arct'Alg in hydrogel membranes to obtain a release device for cosmetics. Arct'Alg is an aqueous extract which has excellent anti-oxidant, lipolytic, anti-inflammatory and cytostimulant action. Study on mechanical and physical-chemical properties and biocompatibility in vitro of hydrogel membranes of poly(vinyl-2- pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) obtained by ionizing radiation crosslinking have been performed. The physical-chemical characterization of polymeric matrices was carried out by gel fraction and swelling tests and biocompatibility by in vitro test of cytotoxicity by using the technique of neutral red incorporation. In the gel fraction test, both the PVP and PVA hydrogel showed a high crosslinking degree. The PVP hydrogel showed a greater percentage of swelling in relation to PVA and the cytotoxicity test of the hydrogels showed non-toxicity effect. The cytostimulation property of Arct'Alg was verified by the cytostimulation test with rabbit skin cells, it was showed an increase at about 50% of the cells when in contact with 0,5% of active agent. The hydrogel membranes prepared with 3% of Arct'Alg were subjected to the release test in an incubator at 37 degree C and aliquots collected during the test were quantified by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that the PVP hydrogel membranes released about 50% of Arct'Alg incorporated and the PVA hydrogel membranes at about 30%. In the cytostimulation test of released Arct'Alg, the PVP device showed an

  17. Radiation synthesis of supported hydrogels for biomedical and biotechnological purposes

    International Nuclear Information System (INIS)

    Since the commencement of this IAEA Research Project in 1997, attempts have been made to synthesize and characterize different hydrogels by using gamma irradiation as initiator. The factors affecting the preparation and homogeneity of prepared hydrogels were thoroughly investigated. Different polymeric materials and monomers were used for the preparation of these hydrogels. Characterization and possibility of their practicable uses were studied. Biomedical and histological studies on some grafted co-polymers showed that the grafted materials seem to be inert. Consequently, it might be used as biocompatible materials. The hemodialysis application was studied to find that the prepared membranes by radiation grafting method possessed good properties and they are of great interest in the field of separation of toxic materials from blood. Smart hydrogels were prepared for drug delivery systems. Butyl acrylate and methacrylic acid co-polymer gels showed a good sensitivity to the pH change for possible use in the field of drug delivery systems specifically for colon. Temperature and pH- sensitive terpolymer for modulated delivery of drugs was also investigated. Terpolymer hydrogels composed of PVA, NIPAAm and different pH-sensitive polymers such as acrylic acid, methacrylic acid and N-N dimethyl aminoethyl methacryate were prepared. The equilibrium swelling for the prepared different terpolymers was thoroughly investigated at various pH's. The hydrophilicity of NIPAAm and other pH-sensitive co-monomer greatly influences the critical collapse pH- of the terpolymer. Immobilization of invertase by radiation-induced polymerization of poly (vinyl alcohol) solution and acrylamide was also studied. The effect of crosslinking agent on the activity of enzyme was studied to show that as the content of crosslinking agent increases the relative activity of the enzyme decreases. The pH effect on the activity of the immobilized invertase was investigated to find that the optimum acting

  18. Electrospinning of Bioactive Dex-PAA Hydrogel Fibers

    Science.gov (United States)

    Louie, Katherine Boyook

    In this work, a novel method is developed for making nano- and micro-fibrous hydrogels capable of preventing the rejection of implanted materials. This is achieved by either (1) mimicking the native cellular environment, to exert fine control over the cellular response or (2) acting as a protective barrier, to camouflage the foreign nature of a material and evade recognition by the immune system. Comprehensive characterization and in vitro studies described here provide a foundation for developing substrates for use in clinical applications. Hydrogel dextran and poly(acrylic acid) (PAA) fibers are formed via electrospinning, in sizes ranging from nanometers to microns in diameter. While "as-electrospun" fibers are continuous in length, sonication is used to fragment fibers into short fiber "bristles" and generate nano- and micro- fibrous surface coatings over a wide range of topographies. Dex-PAA fibrous surfaces are chemically modified, and then optimized and characterized for non-fouling and ECM-mimetic properties. The non-fouling nature of fibers is verified, and cell culture studies show differential responses dependent upon chemical, topographical and mechanical properties. Dex-PAA fibers are advantageously unique in that (1) a fine degree of control is possible over three significant parameters critical for modifying cellular response: topography, chemistry and mechanical properties, over a range emulating that of native cellular environments, (2) the innate nature of the material is non-fouling, providing an inert background for adding back specific bioactive functionality, and (3) the fibers can be applied as a surface coating or comprise the scaffold itself. This is the first reported work of dex-PAA hydrogel fibers formed via electrospinning and thermal cross-linking, and unique to this method, no toxic solvents or cross-linking agents are needed to create hydrogels or for surface attachment. This is also the first reported work of using sonication to

  19. Structural and mechanical properties of UV-photo-cross-linked poly(N-vinyl-2-pyrrolidone) hydrogels.

    Science.gov (United States)

    D'Errico, Gerardino; De Lellis, Marco; Mangiapia, Gaetano; Tedeschi, Annamaria; Ortona, Ornella; Fusco, Sabato; Borzacchiello, Assunta; Ambrosio, Luigi

    2008-01-01

    Biocompatible poly( N-vinyl-2-pyrrolidone) (PVP) hydrogels have been produced by UV irradiation of aqueous polymer mixtures, using a high-pressure mercury lamp. The resulting materials have been characterized by a combination of experimental techniques, including rheology, small-angle neutron scattering (SANS), electron paramagnetic resonance (EPR), and pulsed gradient spin-echo nuclear magnetic resonance (PGSE-NMR), to put in evidence the relationship between the microstructural properties and the macrofunctional behavior of the gels. Viscoelastic measurements showed that UV photo-cross-linked PVP hydrogels present a strong gel mechanical behavior and viscoelastic moduli values similar to those of biological gels. The average distance between the cross-linking points of the polymer network was estimated from the hydrogels elastic modulus. However, SANS measurements showed that the network microstructure is highly inhomogeneous, presenting polymer-rich regions more densely cross-linked, surrounded by a water-rich environment. EPR and PGSE-NMR data further support the existence of these water-rich domains. Inclusion of a third component, such as glycerol, in the PVP aqueous mixture to be irradiated has been also investigated. A small amount of glycerol (hydrogel, while higher amounts significantly affect the cross-linking process. PMID:18163572

  20. WOOD HEMICELLULOSE/CHITOSAN-BASED SEMI-INTERPENETRATING NETWORK HYDROGELS: MECHANICAL, SWELLING AND CONTROLLED DRUG RELEASE PROPERTIES

    Directory of Open Access Journals (Sweden)

    Muzaffer Ahmet Karaaslan

    2010-04-01

    Full Text Available 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 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 effects 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 the 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.