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Sample records for carboxymethyl-kappacarrageenan hydrogels crosslinked

  1. Hydrogels with covalent and noncovalent crosslinks

    Science.gov (United States)

    Kilck, Kristi L. (Inventor); Yamaguchi, Nori (Inventor)

    2013-01-01

    A method for targeted delivery of therapeutic compounds from hydrogels is presented. The method involves administering to a cell a hydrogel in which a therapeutic compound is noncovalently bound to heparin. The hydrogel may contain covalent and non-covalent crosslinks.

  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. A constitutive model of nanocomposite hydrogels with nanoparticle crosslinkers

    Science.gov (United States)

    Wang, Qiming; Gao, Zheming

    2016-09-01

    Nanocomposite hydrogels with only nanoparticle crosslinkers exhibit extraordinarily higher stretchability and toughness than the conventional organically crosslinked hydrogels, thus showing great potential in the applications of artificial muscles and cartilages. Despite their potential, the microscopic mechanics details underlying their mechanical performance have remained largely elusive. Here, we develop a constitutive model of the nanoparticle hydrogels to elucidate the microscopic mechanics behaviors, including the microarchitecture and evolution of the nanoparticle crosslinked polymer chains during the mechanical deformation. The constitutive model enables us to understand the Mullins effect of the nanocomposite hydrogels, and the effects of nanoparticle concentrations and sizes on their cyclic stress-strain behaviors. The theory is quantitatively validated by the tensile tests on a nanocomposite hydrogel with nanosilica crosslinkers. The theory can also be extended to explain the mechanical behaviors of existing hydrogels with nanoclay crosslinkers, and the necking instability of the composite hydrogels with both nanoparticle crosslinkers and organic crosslinkers. We expect that this constitutive model can be further exploited to reveal mechanics behaviors of novel particle-polymer chain interactions, and to design unprecedented hydrogels with both high stretchability and toughness.

  4. 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.

  5. 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

  6. Magnetically Remanent Hydrogels with Colloidal Crosslinkers

    NARCIS (Netherlands)

    van Berkum, S.

    2014-01-01

    Hydrogels are widely used in biomedical applications such as drug delivery and tissue engineering. In this research, the feasibility of a hydrogel with embedded magnetic nanoparticles, also called a ferrogel, for biosensor applications was tested. A pH sensitive poly(acrylic acid) hydrogel was used

  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. 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...

  10. Collagen/elastin hydrogels cross-linked by squaric acid.

    Science.gov (United States)

    Skopinska-Wisniewska, J; Kuderko, J; Bajek, A; Maj, M; Sionkowska, A; Ziegler-Borowska, M

    2016-03-01

    Hydrogels based on collagen and elastin are very valuable materials for medicine and tissue engineering. They are biocompatible; however their mechanical properties and resistance for enzymatic degradation need to be improved by cross-linking. Up to this point many reagents have been tested but more secure reactants are still sought. Squaric acid (SqAc), 3,4-dihydroxy 3-cyclobutene 1,2-dione, is a strong, cyclic acid, which reacts easily with amine groups. The properties of hydrogels based on collagen/elastin mixtures (95/5, 90/10) containing 5%, 10% and 20% of SqAc and neutralized via dialysis against deionized water were tested. Cross-linked, 3-D, transparent hydrogels were created. The cross-linked materials are stiffer and more resistant to enzymatic degradation than those that are unmodified. The pore size, swelling ability and surface polarity are reduced due to 5% and 10% of SqAc addition. At the same time, the cellular response is not significantly affected by the cross-linking. Therefore, squaric acid would be regarded as a safe, effective cross-linking agent.

  11. 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...

  12. Synthesis of silver nanoparticles in hydrogels crosslinked by ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Alcantara, Maria Tania S.; Oliani, Washington L.; Brant, Antonio J.C.; Oliveira, Maria Jose A. de; Riella, Humberto Gracher; Lugao, Ademar B., E-mail: maratalcantara@uol.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Hydrogel is defined as a polymeric material which exhibits the ability to swell and retain a significant fraction of water within its structure without dissolving the polymeric network. Silver nanoparticles (AgNPs) are used in a range of medicinal products based on hydrogels and diverse other products due to their antibacterial properties at low concentrations. The use of ionizing radiation in the production process of hydrogels of poly(N-vinyl-2-pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) in aqueous solutions enables the crosslinking of their polymer chains. If polymer solutions contain Ag{sup +} ions, these can be reduced radiolytically to nanocrystalline silver. The objective of this study was to investigate the reduction of Ag{sup +} ions by gamma-irradiation for the synthesis of AgNPs in hydrogels of PVA and PVP as main polymers and to make a comparison of the performance of the two polymeric matrices, chiefly focusing on the effect of the AgNPs' synthesis on the crosslinking of both polymers. The properties of the hydrogel matrices obtained were evaluated from tests of gel fraction, swelling in water, and stress-strain. The results of mechanical properties of PVA matrix were higher than those of PVP one whereas the latter exhibited a higher swelling degree. The reduction of silver ions was confirmed by UV-visible absorption spectrum, whose characteristics also indicated the formation of silver nanoparticles in both arrays. (author)

  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

    Directory of Open Access Journals (Sweden)

    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. 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.

  16. 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.

  17. Crosslinker effects on functional properties of alginate/N-succinylchitosan based hydrogels.

    Science.gov (United States)

    Straccia, Maria Cristina; Romano, Ida; Oliva, Adriana; Santagata, Gabriella; Laurienzo, Paola

    2014-08-01

    In this paper, physico-chemical, mechanical and antimicrobial properties of hydrogels based on alginate/N-succinylchitosan blends crosslinked by calcium or zinc ions containing cellulose microfibers were investigated and discussed. With respect to plain alginate hydrogels, the addition of N-succinylchitosan significantly improved properties such as swelling degree and stability in saline solution. The water vapour transmission rate confirmed that all the hydrogels were able to assure a moist wound environment. Morphological analysis showed a good embedding of fibres within the zinc crosslinked hydrogels. In addition, zinc-crosslinked hydrogels evidenced antimicrobial activity against two common skin pathogenic bacteria, Staphylococcus aureus and Escherichia coli. Cytotoxicity assays proved that the amount of zinc released is slightly over the toxic level. Overall, the characteristics of the zinc-crosslinked hydrogels showed their potential interest as materials for wound dressing.

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

    Energy Technology Data Exchange (ETDEWEB)

    Alcantara, Mara Tania S.; Lugao, Ademar B., E-mail: maratalcantara@uol.com.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Taqueda, Maria Elena S. [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Quimica

    2009-07-01

    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

    Directory of Open Access Journals (Sweden)

    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

    Energy Technology Data Exchange (ETDEWEB)

    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.

    Directory of Open Access Journals (Sweden)

    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. Novel antimicrobial superporous cross-linked chitosan/pyromellitimide benzoyl thiourea hydrogels.

    Science.gov (United States)

    Mohamed, Nadia A; Abd El-Ghany, Nahed A; Fahmy, Mona M

    2016-01-01

    In this work, chitosan (CS) was cross-linked with different amounts of pyromellitimide benzoyl thiourea moieties. The structure of the cross-linked CS was confirmed by elemental analyses, FTIR and (1)H- NMR spectroscopy. The cross-linking process proceeds via reacting of the amino groups of CS with the isothiocyanate groups of the N,N'-bis [4-(isothiocyanate carbonyl)phenyl] pyromellitimide cross-linker. The amount of the cross-linker was varied with respect to CS to produce four new pyromellitimide benzoyl thiourea cross-linked CS (PIBTU-CS) hydrogels designated as PIBTU-CS-1, PIBTU-CS-2, PIBTU-CS-3, and PIBTU-CS-4 of increasing cross-linking degree percent of 11, 22, 44 and 88%, respectively. The scanning electron microscopy observation indicates the extremely porous structure of the hydrogels. XRD results showed that the crystallinity of CS was decreased upon cross-linking. The four hydrogels exhibit a higher antibacterial activity on Bacillus subtilis and Streptococcus pneumoniae as Gram positive bacteria and against Escherichia coli as Gram negative bacteria and higher antifungal activity on Aspergillus fumigatus, Syncephalastrum racemosum and Geotricum candidum than that of the parent CS as shown from their higher inhibition zone diameters and their lower MIC values. The swell ability of the hydrogel as well as their antimicrobial activity increased with increasing cross-linking density.

  7. 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.

  8. 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

  9. 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.

  10. 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...

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

    Science.gov (United States)

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

    2015-10-01

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

  12. 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

  13. 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

  14. 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.

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

    Science.gov (United States)

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

    2012-01-01

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

  16. Application of UVA-riboflavin crosslinking to enhance the mechanical properties of extracellular matrix derived hydrogels.

    Science.gov (United States)

    Ahearne, Mark; Coyle, Aron

    2016-02-01

    Hydrogels derived from extracellular matrix (ECM) have become increasing popular in recent years, particularly for use in tissue engineering. One limitation with ECM hydrogels is that they tend to have poor mechanical properties compared to native tissues they are trying to replicate. To address this problem, a UVA (ultraviolet-A) riboflavin crosslinking technique was applied to ECM hydrogels to determine if it could be used to improve their elastic modulus. Hydrogels fabricated from corneal, cardiac and liver ECM were used in this study. The mechanical properties of the hydrogels were characterized using a spherical indentation technique. The microstructure of the hydrogels and the cytotoxic effect of crosslinking on cell seeded hydrogels were also evaluated. The combination of UVA light and riboflavin solution led to a significant increase in elastic modulus from 6.8kPa to 24.7kPa, 1.4kPa to 6.9kPa and 0.9kPa to 1.6kPa for corneal, cardiac and liver ECM hydrogels respectively. The extent of this increase was dependent on a number of factors including the UVA exposure time and the initial hydrogel concentration. There were also a high percentage of viable cells within the cell seeded hydrogels with 94% of cells remaining viable after 90min exposure to UVA light. These results suggest that UVA-riboflavin crosslinking is an effective approach for improving the mechanical properties of ECM hydrogels without resulting in a significant reduction of cell viability.

  17. 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.

  18. 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

  19. Metal cation cross-linked nanocellulose hydrogels as tissue engineering substrates.

    Science.gov (United States)

    Zander, Nicole E; Dong, Hong; Steele, Joshua; Grant, John T

    2014-01-01

    The use of cellulose materials for biomedical applications is attractive due to their low cost, biocompatibility, and biodegradability. Specific processing of cellulose to yield nanofibrils further improves mechanical properties and suitability as a tissue engineering substrate due to the similarity to the fibrous structure, porosity, and size-scale of the native extracellular matrix. In order to generate the substrate, nanocellulose hydrogels were fabricated from carboxylated cellulose nanofibrils via hydrogelation using metal salts. Hydrogels cross-linked with Ca(2+) and Fe(3+) were investigated as tissue culture substrates for C3H10T1/2 fibroblast cells. Control substrates as well as those with physically adsorbed and covalently attached fibronectin protein were evaluated with X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and enzyme linked immunosorbent assay (ELISA). Significantly more cells were attached to surfaces modified with protein, with the highest number of cells adhered to the calcium cross-linked hydrogels with covalently attached protein.

  20. 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

  1. 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.

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

    Science.gov (United States)

    Wong, Rachel Shet Hui; Ashton, Mark; Dodou, Kalliopi

    2015-01-01

    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. PMID:26371031

  3. 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.

  4. 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.

  5. 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

  6. Enzymatically crosslinked gelatin hydrogel promotes the proliferation of adipose tissue-derived stromal cells

    Science.gov (United States)

    Ren, Xiaomei; Long, Haiyan; Qian, Hong; Ma, Kunlong

    2016-01-01

    Gelatin hydrogel crosslinked by microbial transglutaminase (mTG) exhibits excellent performance in cell adhesion, proliferation, and differentiation. We examined the gelation time and gel strength of gelatin/mTG hydrogels in various proportions to investigate their physical properties and tested their degradation performances in vitro. Cell morphology and viability of adipose tissue-derived stromal cells (ADSCs) cultured on the 2D gel surface or in 3D hydrogel encapsulation were evaluated by immunofluorescence staining. Cell proliferation was tested via Alamar Blue assay. To investigate the hydrogel effect on cell differentiation, the cardiac-specific gene expression levelsof Nkx2.5, Myh6, Gja1, and Mef2c in encapsulated ADSCs with or without cardiac induction medium were detected by real-time RT-PCR. Cell release from the encapsulated status and cell migration in a 3D hydrogel model were assessed in vitro. Results show that the gelatin/mTG hydrogels are not cytotoxic and that their mechanical properties are adjustable. Hydrogel degradation is related to gel concentration and the resident cells. Cell growth morphology and proliferative capability in both 2D and 3D cultures were mainly affected by gel concentration. PCR result shows that hydrogel modulus together with induction medium affects the cardiac differentiation of ADSCs. The cell migration experiment and subcutaneous implantation show that the hydrogels are suitable for cell delivery. PMID:27703850

  7. 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.

  8. Hyperbranched poly(glycidol)/poly(ethylene oxide) crosslinked hydrogel for tissue engineering scaffold using e-beams.

    Science.gov (United States)

    Haryanto; Singh, Deepti; Huh, Pil Ho; Kim, Seong Cheol

    2016-01-01

    A microporous hydrogel scaffold was developed from hyperbranched poly(glycidol) (HPG) and poly(ethylene oxide) (PEO) using electron beam (e-beam) induced cross-linking for tissue engineering applications. In this study, HPG was synthesized from glycidol using trimethylol propane as a core initiator and cross-linked hydrogels were made using 0, 10, 20, and 30% HPG with respect to PEO. The effects of %-HPG on the swelling ratio, cross-linking density, mechanical properties, morphology, degradation, and cytotoxicity of the hydrogel scaffolds were then investigated. Increasing the HPG content increased the pore size of the hydrogel scaffold, as well as the porosity, elongation at break, degree of degradation and swelling ratio. In contrast, the presence of HPG decreased the cross-linking density of the hydrogel. There was no significant difference in compressive modulus and tensile strength of all compositions. The pore size of hydrogel scaffolds could be easily tailored by controlling the content of HPG in the polymer blend. Evaluation of the cytotoxicity demonstrated that HPG/PEO hydrogel scaffold has potential for use as a matrix for cellular attachment and proliferation. These results indicate that cross-linked HPG/PEO hydrogel can function as a potential material for tissue engineering scaffolds. Moreover, a facile method to prepare hydrogel microporous scaffolds for tissue engineering by e-beam irradiation was developed.

  9. Hypromellose succinate-crosslinked chitosan hydrogel films for potential wound dressing.

    Science.gov (United States)

    Jiang, Qiong; Zhou, Wei; Wang, Jun; Tang, Rupei; Zhang, Di; Wang, Xin

    2016-10-01

    The objective of this study was to develop novel hydrogel films based on carboxyl-modified hypromellose-crosslinked chitosan for potential wound dressing. Hypromellose (HPMC) was grafted with succinic acid to yield hypromellose succinate (HPMCS), and then the reinforced hydrogel films of HPMCS-crosslinked chitosan (HPMCS-CS) were prepared through amide bond formation using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N- hydroxysuccinimide (NHS) as a catalyst. Compared to that of blend film, mechanical properties of HPMCS-CS hydrogel films were significantly enhanced both in dry and swollen state. To assess the applicability of HPMCS-CS hydrogel films as wound dressing, the swelling behavior, water vapor transmission rate (WVTR), oxygen permeability, biocompatibility (cytotoxicity and hemolysis), in vitro drug release and bactericidal properties were analyzed. The results indicated that HPMCS-CS hydrogel films with good biocompatibility possess high swelling ratio, proper WVTR, and oxygen permeability, which might accelerate tissue regeneration. Meanwhile, gentamycin sulfate release from drug-loaded HPMCS-CS hydrogel films were sustained, which would help to protect wound from infection. PMID:27222285

  10. Rheological study of in-situ crosslinkable hydrogels based on hyaluronanic acid, collagen and sericin.

    Science.gov (United States)

    Vulpe, Raluca; Le Cerf, Didier; Dulong, Virginie; Popa, Marcel; Peptu, Catalina; Verestiuc, Liliana; Picton, Luc

    2016-12-01

    The elaboration of chemically crosslinked hydrogels based on collagen (C), hyaluronanic acid (HA) and sericin (S) with different polymer ratios was investigated by in-situ rheology. This reaction was performed via amide or ester bond reaction activated by carbodiimide, in pure water. Prior to molecule crosslinking, the rheological behaviour of the biopolymers (alone or in mixture) was characterized in a semi-dilute concentration regime. Both flow and dynamic measurements showed that uncrosslinked collagen alone appears to be rather elastic with yield stress properties, whereas uncrosslinked HA alone appears to be rather shear thinning and viscoelastic in agreement with entangled polymer behaviour. Sericin exhibited Newtonian low viscosity behaviour according to its very low molar mass. Before crosslinking, HA exhibited viscoelastic behaviour at concentrations above the critical entangled concentration (C*) in the mixtures, thus HA shows promise as a matrix for future crosslinked networks, whereas sericin did not significantly modify the rheology. During the reaction, followed by rheology, the kinetics were slower for pure HA systems compared with the mixtures (i.e., with added collagen and/or to a lesser extent sericin). At the same time, the final network of hydrogels (i.e., the elastic modulus) was more structured in the mixture based systems. This result is explained by ester bonds (the only possibility for pure HA systems), which are less favourable and reactive than amide bonds (possible with sericin and collagen). The presence of collagen in the HA matrix reinforced the hydrogel network. SEM studies confirmed the structure of the hydrogels, and in vitro degradability was globally consistent with the effect of the selected enzyme according to the hydrogel composition. All the elaborated hydrogels were non-cytotoxic in vitro. PMID:27612727

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

    Science.gov (United States)

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

    2014-06-15

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

  12. Effects of alginate hydrogel cross-linking density on mechanical and biological behaviors for tissue engineering.

    Science.gov (United States)

    Jang, Jinah; Seol, Young-Joon; Kim, Hyeon Ji; Kundu, Joydip; Kim, Sung Won; Cho, Dong-Woo

    2014-09-01

    An effective cross-linking of alginate gel was made through reaction with calcium carbonate (CaCO3). We used human chondrocytes as a model cell to study the effects of cross-linking density. Three different pore size ranges of cross-linked alginate hydrogels were fabricated. The morphological, mechanical, and rheological properties of various alginate hydrogels were characterized and responses of biosynthesis of cells encapsulated in each gel to the variation in cross-linking density were investigated. Desired outer shape of structure was maintained when the alginate solution was cross-linked with the applied method. The properties of alginate hydrogel could be tailored through applying various concentrations of CaCO3. The rate of synthesized GAGs and collagens was significantly higher in human chondrocytes encapsulated in the smaller pore structure than that in the larger pore structure. The expression of chondrogenic markers, including collagen type II and aggrecan, was enhanced in the smaller pore structure. It was found that proper structural morphology is a critical factor to enhance the performance and tissue regeneration.

  13. 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

  14. 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...... the concentration of counterions within the hydrogel to keep the interior close to uncharged, which is similar to what has been observed for polyelectrolyte brushes. Changes in pH and ionic strength affect the adhesion force and the friction force between the silica surface and the hydrogel layer...

  15. 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.

  16. Kinetic release studies of nitrogen-containing bisphosphonate from gum acacia crosslinked hydrogels.

    Science.gov (United States)

    Aderibigbe, B A; Varaprasad, K; Sadiku, E R; Ray, S S; Mbianda, X Y; Fotsing, M C; Owonubi, S J; Agwuncha, S C

    2015-02-01

    Natural polymer hydrogels are useful for controlling release of drugs. In this study, hydrogels containing gum acacia were synthesized by free-radical polymerization of acrylamide with gum acacia. The effect of gum acacia in the hydrogels on the release mechanism of nitrogen-containing bisphosphonate (BP) was studied at pH 1.2 and 7.4. The hydrogels exhibited high swelling ratios at pH 7.4 and low swelling ratios at pH 1.2. The release study was performed using UV-Visible spectroscopy via complex formation with Fe(III) ions. At pH 1.2, the release profile was found to be anomalous while at pH 7.4, the release kinetic of BP was a perfect zero-order release mechanism. The hydrogels were found to be pH-sensitive and the release profiles of the BP were found to be influenced by the degree of crosslinking of the hydrogel network with gum acacia. The preliminary results suggest that these hydrogels are promising devices for controlled delivery of bisphosphonate to the gastrointestinal region.

  17. 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.

  18. Synthesis and antimicrobial activity of some novel cross-linked chitosan hydrogels.

    Science.gov (United States)

    Mohamed, Nadia Ahmed; Fahmy, Mona Mohamed

    2012-01-01

    Four novel hydrogels based on chitosan were synthesized via a cross-linking reaction of chitosan with different concentrations of oxalyl bis 4-(2,5-dioxo-2H-pyrrol- 1(5H)-yl)benzamide. Their structures were confirmed by fourier transform infrared X-ray (FTIR), scanning electron microscopy (SEM) and X-ray diffraction. The antimicrobial activities of the hydrogels against two crop-threatening pathogenic fungi namely: Aspergillus fumigatus (A. fumigatus, RCMBA 06002), and Aspergillus niger (A. niger, RCMBA 06106), and five bacterial species namely: Bacillis subtilis (B. subtilis, RCMBA 6005), Staphylococcus aureus (S. aureus, RCMBA 2004), Streptococcus pneumoniae (S. pneumonia, RCMB 000101) as Gram positive bacteria, and Salmonella typhimurium (S. typhimurium, RCMB 000104), and Escherichia coli (E. coli, RCMBA 5003) as Gram negative bacteria have been investigated. The prepared hydrogels showed much higher antimicrobial activities than that of the parent chitosan. The hydrogels were more potent in case of Gram-positive bacteria than Gram-negative bacteria. Increasing the degree of cross-linking in the hydrogels resulted in a weaker antimicrobial activity.

  19. Synthesis and Antimicrobial Activity of Some Novel Cross-Linked Chitosan Hydrogels

    Directory of Open Access Journals (Sweden)

    Mona Mohamed Fahmy

    2012-09-01

    Full Text Available Four novel hydrogels based on chitosan were synthesized via a cross-linking reaction of chitosan with different concentrations of oxalyl bis 4-(2,5-dioxo-2H-pyrrol-1(5H-ylbenzamide. Their structures were confirmed by fourier transform infrared X-ray (FTIR, scanning electron microscopy (SEM and X-ray diffraction. The antimicrobial activities of the hydrogels against two crop-threatening pathogenic fungi namely: Aspergillus fumigatus (A. fumigatus, RCMBA 06002, and Aspergillus niger (A. niger, RCMBA 06106, and five bacterial species namely: Bacillis subtilis (B. subtilis, RCMBA 6005, Staphylococcus aureus (S. aureus, RCMBA 2004, Streptococcus pneumoniae (S. pneumonia, RCMB 000101 as Gram positive bacteria, and Salmonella typhimurium (S. typhimurium, RCMB 000104, and Escherichia coli (E. coli, RCMBA 5003 as Gram negative bacteria have been investigated. The prepared hydrogels showed much higher antimicrobial activities than that of the parent chitosan. The hydrogels were more potent in case of Gram-positive bacteria than Gram-negative bacteria. Increasing the degree of cross-linking in the hydrogels resulted in a weaker antimicrobial activity.

  20. 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

  1. 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

  2. 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

  3. 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...

  4. 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...

  5. Evaluation of an alginate-gelatine crosslinked hydrogel for bioplotting.

    Science.gov (United States)

    Zehnder, Tobias; Sarker, Bapi; Boccaccini, Aldo R; Detsch, Rainer

    2015-04-08

    Using additive manufacturing to create hydrogel scaffolds which incorporate homogeneously distributed, immobilized cells in the context of biofabrication approaches represents an emerging and expanding field in tissue engineering. Applying hydrogels for additive manufacturing must consider the material processing properties as well as their influence on the immobilized cells. In this work alginate-dialdehyde (ADA), a partially oxidized alginate, was used as a basic material to improve the physico-chemical properties of the hydrogel for cell immobilization. At first, the processing ability of the gel using a bioplotter and the compatibility of the process with MG-63 osteoblast like cells were investigated. The metabolic and mitochondrial activities increased at the beginning of the incubation period and they balanced at a relatively high level after 14-28 days of incubation. During this incubation period the release of vascular endothelial growth factor-A also increased. After 28 days of incubation the cell morphology showed a spreading morphology and cells were seen to move out of the scaffold struts covering the whole scaffold structure. The reproducible processing capability of alginate-gelatine (ADA-GEL) and the compatibility with MG-63 cells were proven, thus the ADA-GEL material is highlighted as a promising matrix for applications in biofabrication.

  6. 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...

  7. Crosslinked poly(vinyl alcohol) hydrogels for wound dressing applications: A review of remarkably blended polymers

    OpenAIRE

    Elbadawy A. Kamoun; Xin Chen; Mohamed S. Mohy Eldin; El-Refaie S. Kenawy

    2015-01-01

    A series of excellent poly(vinyl alcohol) (PVA)/polymers blend hydrogel were reviewed using different crosslinking types to obtain proper polymeric dressing materials, which have satisfied biocompatibility and sufficient mechanical properties. The importance of biodegradable–biocompatible synthetic polymers such as PVA, natural polymers such as alginate, starch, and chitosan or their derivatives has grown significantly over the last two decades due to their renewable and desirable biological ...

  8. 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...

  9. 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...

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

    Science.gov (United States)

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

    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 composed of electrospun cross-linked nanofiber networks containing redox agents. The hydrogels process high healing rate ranging from seconds to days and great mechanical strengths with storage modulus up to 0.1 MPa. More interestingly, when the healing layer is embedded into the crack of the hydrogel, accelerated self-healing is observed and the healing efficiency is about 80%. The healing layer encourages molecular diffusion as well as further cross-linking in the crack region of the hydrogel, responsible for enhanced healing efficiency. PMID:24091865

  11. 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

  12. Photo-Crosslinked Biodegradable Hydrogels Prepared From Fumaric Acid Monoethyl Ester-Functionalized Oligomers for Protein Delivery

    NARCIS (Netherlands)

    Jansen, Janine; Mihov, George; Feijen, Jan; Grijpma, Dirk W.

    2012-01-01

    Photo-crosslinkable, fumaric acid monoethyl ester-functionalized triblock oligomers are synthesized and copolymerized with N-vinyl-2-pyrrolidone to form biodegradable photo-crosslinked hydrogels. Poly(ethylene glycol) is used as the middle hydrophilic segment and the hydrophobic segments are based o

  13. High-Strength, Tough, Fatigue Resistant, and Self-Healing Hydrogel Based on Dual Physically Cross-Linked Network.

    Science.gov (United States)

    Gong, Zhengyu; Zhang, Guoping; Zeng, Xiaoliang; Li, Jinhui; Li, Gang; Huang, Wangping; Sun, Rong; Wong, Chingping

    2016-09-14

    Hydrogels usually suffer from low mechanical strength, which largely limit their application in many fields. In this Research Article, we prepared a dual physically cross-linked hydrogel composed of poly(acrylamide-co-acrylic acid) (PAM-co-PAA) and poly(vinyl alcohol) (PVA) by simple two-steps methods of copolymerization and freezing/thawing. The hydrogen bond-associated entanglement of copolymer chains formed as cross-linking points to construct the first network. After being subjected to the freezing/thawing treatment, PVA crystalline domains were formed to serve as knots of the second network. The hydrogels were demonstrated to integrate strength and toughness (1230 ± 90 kPa and 1250 ± 50 kJ/m(3)) by the introduction of second physically cross-linked network. What̀s more, the hydrogels exhibited rapid recovery, excellent fatigue resistance, and self-healing property. The dynamic property of the dual physically cross-linked network contributes to the excellent energy dissipation and self-healing property. Therefore, this work provides a new route to understand the toughness mechanism of dual physically cross-linked hydrogels, hopefully promoting current hydrogel research and expanding their applications. PMID:27548327

  14. 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.

  15. 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.

  16. 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

  17. Transparent crosslinked ultrashort peptide hydrogel dressing with high shape-fidelity accelerates healing of full-thickness excision wounds.

    Science.gov (United States)

    Seow, Wei Yang; Salgado, Giorgiana; Lane, E Birgitte; Hauser, Charlotte A E

    2016-01-01

    Wound healing is a major burden of healthcare systems worldwide and hydrogel dressings offer a moist environment conducive to healing. We describe cysteine-containing ultrashort peptides that self-assemble spontaneously into hydrogels. After disulfide crosslinking, the optically-transparent hydrogels became significantly stiffer and exhibited high shape fidelity. The peptide sequence (LIVAGKC or LK6C) was then chosen for evaluation on mice with full-thickness excision wounds. Crosslinked LK6C hydrogels are handled easily with forceps during surgical procedures and offer an improvement over our earlier study of a non-crosslinked peptide hydrogel for burn wounds. LK6C showed low allergenic potential and failed to provoke any sensitivity when administered to guinea pigs in the Magnusson-Kligman maximization test. When applied topically as a dressing, the medium-infused LK6C hydrogel accelerated re-epithelialization compared to controls. The peptide hydrogel is thus safe for topical application and promotes a superior rate and quality of wound healing. PMID:27600999

  18. In situ-forming click-crosslinked gelatin based hydrogels for 3D culture of thymic epithelial cells.

    Science.gov (United States)

    Truong, Vinh X; Hun, Michael L; Li, Fanyi; Chidgey, Ann P; Forsythe, John S

    2016-07-21

    Hydrogels prepared from naturally derived gelatin can provide a suitable environment for cell attachment and growth, making them favourable materials in tissue engineering. However, physically crosslinked gelatin hydrogels are not stable under physiological conditions while chemical crosslinking of gelatin by radical polymerization may be harmful to cells. In this study, we attached the norbornene functional group to gelatin, which was subsequently crosslinked with a polyethylene glycol (PEG) linker via the nitrile oxide-norbornene click reaction. The rapid crosslinking process allows the hydrogel to be formed within minutes of mixing the polymer solutions under physiological conditions, allowing the gels to be used as injectable materials. The hydrogels properties including mechanical strength, swelling and degradation, can be tuned by changing either the ratio of the reacting groups or the total concentration of the polymer precursors. Murine embryonic fibroblastic cells cultured in soft gels (2 wt% of gelatin and 1 wt% of PEG linker) demonstrated high cell viability as well as similar phenotypic profiles (PDGFRα and MTS15) to Matrigel cultures over 5 days. Thymic epithelial cell and fibroblast co-cultures produced epithelial colonies in these gels following 7 days incubation. These studies demonstrate that gelatin based hydrogels, prepared using "click" crosslinking, provide a robust cell culture platform with retained benefits of the gelatin material, and are therefore suitable for use in various tissue engineering applications. PMID:27217071

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

  1. 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.

  2. Riboflavin-induced photo-crosslinking of collagen hydrogel and its application in meniscus tissue engineering.

    Science.gov (United States)

    Heo, Jiseung; Koh, Rachel H; Shim, Whuisu; Kim, Hwan D; Yim, Hyun-Gu; Hwang, Nathaniel S

    2016-04-01

    A meniscus tear is a common knee injury, but its regeneration remains a clinical challenge. Recently, collagen-based scaffolds have been applied in meniscus tissue engineering. Despite its prevalence, application of natural collagen scaffold in clinical setting is limited due to its extremely low stiffness and rapid degradation. The purpose of the present study was to increase the mechanical properties and delay degradation rate of a collagen-based scaffold by photo-crosslinking using riboflavin (RF) and UV exposure. RF is a biocompatible vitamin B2 that showed minimal cytotoxicity compared to conventionally utilized photo-initiator. Furthermore, collagen photo-crosslinking with RF improved mechanical properties and delayed enzyme-triggered degradation of collagen scaffolds. RF-induced photo-crosslinked collagen scaffolds encapsulated with fibrochondrocytes resulted in reduced scaffold contraction and enhanced gene expression levels for the collagen II and aggrecan. Additionally, hyaluronic acid (HA) incorporation into photo-crosslinked collagen scaffold showed an increase in its retention. Based on these results, we demonstrate that photo-crosslinked collagen-HA hydrogels can be potentially applied in the scaffold-based meniscus tissue engineering.

  3. 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

  4. 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

  5. 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.

  6. 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

  7. Development of tailored and self-mineralizing citric acid-crosslinked hydrogels for in situ bone regeneration.

    Science.gov (United States)

    Sánchez-Ferrero, Aitor; Mata, Álvaro; Mateos-Timoneda, Miguel A; Rodríguez-Cabello, José C; Alonso, Matilde; Planell, Josep; Engel, Elisabeth

    2015-11-01

    Bone tissue engineering demands alternatives overcoming the limitations of traditional approaches in the context of a constantly aging global population. In the present study, elastin-like recombinamers hydrogels were produced by means of carbodiimide-catalyzed crosslinking with citric acid, a molecule suggested to be essential for bone nanostructure. By systematically studying the effect of the relative abundance of reactive species on gelation and hydrogel properties such as functional groups content, degradation and structure, we were able to understand and to control the crosslinking reaction to achieve hydrogels mimicking the fibrillary nature of the extracellular matrix. By studying the effect of polymer concentration on scaffold mechanical properties, we were able to produce hydrogels with a stiffness value of 36.13 ± 10.72 kPa, previously suggested to be osteoinductive. Microstructured and mechanically-tailored hydrogels supported the growth of human mesenchymal stem cells and led to higher osteopontin expression in comparison to their non-tailored counterparts. Additionally, tailored hydrogels were able to rapidly self-mineralize in biomimetic conditions, evidencing that citric acid was successfully used both as a crosslinker and a bioactive molecule providing polymers with calcium phosphate nucleation capacity.

  8. Properties of radiation synthesized PVP-kappa carrageenan hydrogel blends[PVP; Carrageenan; Hydrogels; Radiation crosslinking; Radiation grafting; Semi-interpenetrating network

    Energy Technology Data Exchange (ETDEWEB)

    Abad, L.V. E-mail: lvabad@pnri.dost.gov.ph; Relleve, L.S.; Aranilla, C.T.; Rosa, A.M. dela

    2003-12-01

    Hydrogels have been synthesized from varying concentrations of polyvinyl pyrolidone (PVP) and kappa carrageenan (KC) using gamma radiation. Physical properties such as gel fraction and swelling behavior were determined. Data revealed the presence of a network structure whereby KC is physically entangled into the crosslinked PVP (SIPN). TGA, X-RF and FT-IR analyses of the gel fractions also indicated grafting and crosslinking of the PVP. The degree of grafting and crosslinking depended on the concentrations of KC and PVP. Maximum grafting was obtained at higher KC concentration and lower PVP.

  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. Determining the structure and properties of complex coacervate crosslinked triblock copolymer hydrogels

    Science.gov (United States)

    Krogstad, Daniel; Choi, Soo-Hyung; Spruell, Jason; Lynd, Nathaniel; Kramer, Edward; Tirrell, Matthew

    2012-02-01

    The mechanical properties and structures of functionalized P(AGE-b-EO-b-AGE) hydrogels utilizing complex coacervation as a physical crosslink have been studied. The effects of variables such as polymer concentration, salt concentration, pH, stoichiometric ratios and temperature have been investigated by rheology and SAXS. It was found that the organization of the cores has a very strong effect on the mechanical properties. This can be observed as the storage modulus increases significantly between 15 and 16 wt% corresponding to a transition from a disordered gel to a BCC structure. Another dramatic change is observed when the storage modulus drops between 25 and 30 wt% as the hexagonal structure becomes predominant. Just as polymer concentration causes changes in structure and thus the properties, salt concentration has a similar effect due to the electrostatic nature of the hydrogels. As salt is added, the electrostatic interactions in the cores are screened until they are weak enough that the polymers are dissolved into the matrix. The mechanical properties and the physical nature of the crosslinks lead to the possibility of these gels being used as an injectable drug delivery system.

  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. Mechanically resilient, injectable, and bioadhesive supramolecular gelatin hydrogels crosslinked by weak host-guest interactions assist cell infiltration and in situ tissue regeneration.

    Science.gov (United States)

    Feng, Qian; Wei, Kongchang; Lin, Sien; Xu, Zhen; Sun, Yuxin; Shi, Peng; Li, Gang; Bian, Liming

    2016-09-01

    Although considered promising materials for assisting organ regeneration, few hydrogels meet the stringent requirements of clinical translation on the preparation, application, mechanical property, bioadhesion, and biocompatibility of the hydrogels. Herein, we describe a facile supramolecular approach for preparing gelatin hydrogels with a wide array of desirable properties. Briefly, we first prepare a supramolecular gelatin macromer via the efficient host-guest complexation between the aromatic residues of gelatin and free diffusing photo-crosslinkable acrylated β-cyclodextrin (β-CD) monomers. The subsequent crosslinking of the macromers produces highly resilient supramolecular gelatin hydrogels that are solely crosslinked by the weak host-guest interactions between the gelatinous aromatic residues and β-cyclodextrin (β-CD). The obtained hydrogels are capable of sustaining excessive compressive and tensile strain, and they are capable of quick self healing after mechanical disruption. These hydrogels can be injected in the gelation state through surgical needles and re-molded to the targeted geometries while protecting the encapsulated cells. Moreover, the weak host-guest crosslinking likely facilitate the infiltration and migration of cells into the hydrogels. The excess β-CDs in the hydrogels enable the hydrogel-tissue adhesion and enhance the loading and sustained delivery of hydrophobic drugs. The cell and animal studies show that such hydrogels support cell recruitment, differentiation, and bone regeneration, making them promising carrier biomaterials of therapeutic cells and drugs via minimally invasive procedures. PMID:27294539

  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.

  16. 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.

  17. 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

  18. 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

  19. Multistimuli-Responsive, Moldable Supramolecular Hydrogels Cross-Linked by Ultrafast Complexation of Metal Ions and Biopolymers.

    Science.gov (United States)

    Sun, Zhifang; Lv, Fucong; Cao, Lujie; Liu, Lin; Zhang, Yi; Lu, Zhouguang

    2015-06-26

    A new type of multistimuli-responsive hydrogels cross-linked by metal ions and biopolymers is reported. By mixing the biopolymer chitosan (CS) with a variety of metal ions at the appropriate pH values, we obtained a series of transparent and stable hydrogels within a few seconds through supramolecular complexation. In particular, the CS-Ag hydrogel was chosen as the model and the gelation mechanism was revealed by various measurements. It was found that the facile association of Ag(+) ions with amino and hydroxy groups in CS chains promoted rapid gel-network formation. Interestingly, the CS-Ag hydrogel exhibits sharp phase transitions in response to multiple external stimuli, including pH value, chemical redox reactions, cations, anions, and neutral species. Furthermore, this soft matter showed a remarkable moldability to form shape-persistent, free-standing objects by a fast in situ gelation procedure.

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    A. A. L. Goncalves

    2016-03-01

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

  2. Crosslinked poly(vinyl alcohol hydrogels for wound dressing applications: A review of remarkably blended polymers

    Directory of Open Access Journals (Sweden)

    Elbadawy A. Kamoun

    2015-01-01

    Full Text Available A series of excellent poly(vinyl alcohol (PVA/polymers blend hydrogel were reviewed using different crosslinking types to obtain proper polymeric dressing materials, which have satisfied biocompatibility and sufficient mechanical properties. The importance of biodegradable–biocompatible synthetic polymers such as PVA, natural polymers such as alginate, starch, and chitosan or their derivatives has grown significantly over the last two decades due to their renewable and desirable biological properties. The properties of these polymers for pharmaceutical and biomedical application needs have attracted much attention. Thus, a considered proportion of the population need those polymeric medical applications for drug delivery, wound dressing, artificial cartilage materials, and other medical purposes, where the pressure on alternative polymeric devices in all countries became substantial. The review explores different polymers which have been blended previously in the literature with PVA as wound dressing blended with other polymeric materials, showing the feasibility, property change, and purpose which are behind the blending process with PVA.

  3. 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.

  4. Mechanical Characterization of Photo-crosslinked, Thermoresponsive Hydrogel Thin Films via AFM Nanoindentation

    Science.gov (United States)

    Le, Thao; Aidala, Katherine; Hayward, Ryan

    2014-03-01

    Thin hydrogel films with patterned swelling are known to buckle into programmed three-dimensional shapes, offering approaches to fabricate reversibly self-folding micro-devices for actuators and drug delivery devices. To precisely control the shapes adopted, it is important to quantitatively understand the relationship between swelling and mechanical properties. Furthermore, to understand the buckling pathways and the mechanical responses of the swelled materials, it is also important to identify how the gels undergo stress relaxation. However, the low moduli, high water contents, and micrometer-scale thicknesses of these materials have so far made mechanical characterization difficult. In this study, we use an AFM nanoindentation technique to characterize the mechanical properties of photo-crosslinked, thermoresponsive poly(N-isopropylacrylamide) hydrogel thin films. Simultaneously, we conduct stress relaxation experiments at microscopic indentation lengths to differentiate between the effects of viscoelastic and poroelastic response mechanisms. This research was funded by the Army Research Office through W911NF-11-1-0080 and the NSF Materials Research Science and Engineering Center at the University of Massachusetts through DMR-0820506.

  5. 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.

  6. 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® ...

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. Hydrosoluble, UV-crosslinkable and injectable chitosan for patterned cell-laden microgel and rapid transdermal curing hydrogel in vivo.

    Science.gov (United States)

    Li, Baoqiang; Wang, Lei; Xu, Feng; Gang, Xiaomin; Demirci, Utkan; Wei, Daqing; Li, Ying; Feng, Yujie; Jia, Dechang; Zhou, Yu

    2015-08-01

    Natural and biodegradable chitosan with unique amino groups has found widespread applications in tissue engineering and drug delivery. However, its applications have been limited by the poor solubility of native chitosan in neutral pH solution, which subsequently fails to achieve cell-laden hydrogel at physiological pH. To address this, we incorporated UV crosslinking ability in chitosan, allowing fabrication of patterned cell-laden and rapid transdermal curing hydrogel in vivo. The hydrosoluble, UV crosslinkable and injectable N-methacryloyl chitosan (N-MAC) was synthesized via single-step chemoselective N-acylation reaction, which simultaneously endowed chitosan with well solubility in neutral pH solution, UV crosslinkable ability and injectability. The solubility of N-MAC in neutral pH solution increased 2.21-fold with substitution degree increasing from 10.9% to 28.4%. The N-MAC allowed fabrication of cell-laden microgels with on-demand patterns via photolithography, and the cell viability in N-MAC hydrogel maintained 96.3 ± 1.3% N-MAC allowed rapid transdermal curing hydrogel in vivo within 60s through minimally invasive clinical surgery. Histological analysis revealed that low-dose UV irradiation hardly induced skin injury and acute inflammatory response disappeared after 7 days. N-MAC would allow rapid, robust and cost-effective fabrication of patterned cell-laden polysaccharide microgels with unique amino groups serving as building blocks for tissue engineering and rapid transdermal curing hydrogel in vivo for localized and sustained protein delivery.

  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. 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.

  14. 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

  15. 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.

  16. pH-responsive, dynamically restructuring hydrogels formed by reversible crosslinking of PVA with phenylboronic acid functionalised PPO–PEO–PPO spacers (Jeffamines®)

    NARCIS (Netherlands)

    Piest, Martin; Zhang, Xiaolin; Trinidad, Jeffrey; Engbersen, Johan F.J.

    2011-01-01

    Dynamically restructuring (“self-healing”) hydrogels were prepared by reversible formation of boronic-ester crosslinks between α,ω-phenylboronic acid terminated PPO–PEO–PPO spacers and poly(vinyl alcohol) (PVA). For this purpose two different bis-(phenylboronic acid) functionalised crosslinkers with

  17. 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

  18. Ionically Crosslinked Chitosan Hydrogels for the Controlled Release of Antimicrobial Essential Oils and Metal Ions for Wound Management Applications

    Directory of Open Access Journals (Sweden)

    Wan Li Low

    2016-03-01

    Full Text Available The emerging problems posed by antibiotic resistance complicate the treatment regime required for wound infections and are driving the need to develop more effective methods of wound management. There is growing interest in the use of alternative, broad spectrum, pre-antibiotic antimicrobial agents such as essential oils (e.g., tea tree oil, TTO and metal ions (e.g., silver, Ag+. Both TTO and Ag+ have broad spectrum antimicrobial activity and act on multiple target sites, hence reducing the likelihood of developing resistance. Combining such agents with responsive, controlled release delivery systems such as hydrogels may enhance microbiocidal activity and promote wound healing. The advantages of using chitosan to formulate the hydrogels include its biocompatible, mucoadhesive and controlled release properties. In this study, hydrogels loaded with TTO and Ag+ exhibited antimicrobial activity against P. aeruginosa, S. aureus and C. albicans. Combining TTO and Ag+ into the hydrogel further improved antimicrobial activity by lowering the effective concentrations required, respectively. This has obvious advantages for reducing the potential toxic effects on the healthy tissues surrounding the wound. These studies highlight the feasibility of delivering lower effective concentrations of antimicrobial agents such as TTO and Ag+ in ionically crosslinked chitosan hydrogels to treat common wound-infecting pathogens.

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

    Science.gov (United States)

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

    2016-01-10

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

  20. 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

  1. 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.

  2. Cell-mediated Delivery and Targeted Erosion of Noncovalently Crosslinked Hydrogels

    Science.gov (United States)

    Kiick, Kristi L. (Inventor); Yamaguchi, Nori (Inventor)

    2013-01-01

    A method for targeted delivery of therapeutic compounds from hydrogels is presented. The method involves administering to a cell a hydrogel in which a therapeutic compound is noncovalently bound to heparin.

  3. 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)

  4. Synthesis of cellulose-based superabsorbent hydrogels by high-energy irradiation in the presence of crosslinking agent

    Science.gov (United States)

    Fekete, Tamás; Borsa, Judit; Takács, Erzsébet; Wojnárovits, László

    2016-01-01

    Superabsorbent hydrogels were prepared from aqueous solutions of four cellulose derivatives (carboxymethylcellulose Na-salt - CMC, methylcellulose - MC, hydroxyethylcellulose - HEC and hydroxypropylcellulose - HPC) by gamma irradiation initiated crosslinking. CMC was used for the majority of the measurements. N,N'-methylene-bis-acrylamide (MBA) crosslinking agent was used to modify the gel properties. The crosslink density increased with the MBA concentration, leading to an improved gel fraction and lower water uptake. The crosslinking efficiency was the highest up to 1 w/wpolymer% MBA concentration. Very high MBA content (10 w/wpolymer%) led to a heterogeneous gel structure. Gelation also occurred under milder conditions in the presence of MBA: good gel properties were achieved at significantly lower doses and solute concentrations as compared to crosslinker-free solutions. The time required to reach maximum water uptake increased with the degree of swelling in equilibrium. Swelling properties of CMC gels with lower water uptake showed lower sensitivity to the ionic strength of the solvent.

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

    Science.gov (United States)

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

    2016-11-01

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

  6. Novel hydrogels based on carboxyl pullulan and collagen crosslinking with 1, 4-butanediol diglycidylether for use as a dermal filler: initial in vitro and in vivo investigations.

    Science.gov (United States)

    Li, Xian; Xue, Wenjiao; Zhu, Chenhui; Fan, Daidi; Liu, Yannan; XiaoxuanMa

    2015-12-01

    Novel hydrogels based on carboxyl pullulan (PC) and human-like collagen (HLC) crosslinking with 1,4-butanediol diglycidyl ether (BDDE) are promising soft fillers for tissue engineering due to their highly tunable properties. Recent studies, however, have shown that incorporating hyaluronic acid and BDDE results in hydrogels with a microporous structure, a large pore size and high porosity, which reduce cell adhesion and enhance degradation in vivo. To improve biocompatibility and prevent biodegradation, the use of PC to replace hyaluronic acid in the fabrication of PC/BDDE (PCB) and PC/BDDE/HLC (PCBH) hydrogels was investigated. Preparation of gels with PC is a promising strategy due to the high reactivity, superb selectivity, and mild reaction conditions of PC. In particular, the Schiff base reaction of HLC and PC produces the novel functional group -RCONHR' in PCBH hydrogels. Twenty-four weeks after subcutaneous injection of either PCB or PCBH hydrogel in mice, the surrounding tissue inflammation, enzymatic response and cell attachment were better compared to hyaluronic acid-based hydrogels. However, the biocompatibility, cytocompatibility and non-biodegradability of PCBH were milder than those of the PCB hydrogels both in vivo and in vitro. These results show that the proposed use of PC and HLC for the fabrication of hydrogels is a promising strategy for generating soft filler for tissue engineering.

  7. Microbes encapsulated within crosslinkable polymers

    Energy Technology Data Exchange (ETDEWEB)

    Chidambaram, Devicharan; Liu, Ying; Rafailovich, Miriam H

    2013-02-05

    The invention relates to porous films comprising crosslinked electrospun hydrogel fibers. Viable microbes are encapsulated within the crosslinked electrospun hydrogel fibers. The crosslinked electrospun hydrogel fibers are water insoluble and permeable. The invention also relates to methods of making and using such porous films.

  8. 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.

  9. 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

  10. 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.

  11. Designing of superporous cross-linked hydrogels containing acrylic-based polymer network

    Directory of Open Access Journals (Sweden)

    Ray Debajyoti

    2008-01-01

    Full Text Available Biodegradable cross-linked polymer, 2-hydroxyethyl methacrylate-co-acrylic acid was synthesized by free radical polymerization technique using N,N"-methylene-bis-acrylamide as cross-linker and benzoyl peroxide as reaction initiator. FT-IR, 1 H-NMR, scanning electron microscopy (SEM, and thermogravimetric analysis (TGA studies of the copolymer along with homopolymers were carried out. FT-IR studies showed no interactions on copolymerization. SEM studies of the copolymer were carried out and mean particle size was found to be 50 µm. TGA analysis indicated an increase in thermal stability by cross-linking the polymer network. Swelling behavior of the copolymer showed more swelling by increasing pH of the medum and the prepared polymer was found to be biodegradable. The prepared cross-linked polymer system holds good for further drug delivery studies in connection to its super swelling and biodegradability.

  12. Dialing in the Ratio of Covalent and Coordination Cross-links in Self-healing Hydrogels

    DEFF Research Database (Denmark)

    Andersen, Amanda; Krogsgaard, Marie; Birkedal, Henrik

    Supported by the diverse chemistry of the catechol group, pH-responsive, mussel-inspired hydrogels has drawn considerable attention due to the presence of reversible catecholato–metal bonds, which incorporates self-healing properties. Through oxidation, catechols also participates in covalent cross...

  13. 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

  14. Enzymatically cross-linked gelatin-phenol hydrogels with a broader stiffness range for osteogenic differentiation of human mesenchymal stem cells.

    Science.gov (United States)

    Wang, Li-Shan; Du, Chan; Chung, Joo Eun; Kurisawa, Motoichi

    2012-05-01

    An injectable hydrogel system, composed of gelatin-hydroxyphenylpropionic acid (Gtn-HPA) conjugates chemically cross-linked by an enzyme-mediated oxidation reaction, has been designed as a biodegradable scaffold for tissue engineering. In light of the role of substrate stiffness on cell differentiation, we herein report a newly improved Gtn hydrogel system with a broader range of stiffness control that uses Gtn-HPA-tyramine (Gtn-HPA-Tyr) conjugates to stimulate the osteogenic differentiation of human mesenchymal stem cells (hMSCs). The Gtn-HPA-Tyr conjugate was successfully synthesized through a further conjugation of Tyr to Gtn-HPA conjugate by means of a general carbodiimide/active ester-mediated coupling reaction. Proton nuclear magnetic resonance and UV-visible measurements showed a higher total phenol content in the Gtn-HPA-Tyr conjugate than that content in the Gtn-HPA conjugate. The Gtn-HPA-Tyr hydrogels were formed by the oxidative coupling of phenol moieties catalyzed by hydrogen peroxide (H(2)O(2)) and horseradish peroxidase (HRP). Rheological studies revealed that a broader range of storage modulus (G') of Gtn-HPA-Tyr hydrogel (600-26,800 Pa) was achieved using different concentrations of H(2)O(2), while the G' of the predecessor Gtn-HPA hydrogels was limited to the range of 1000 to 13,500 Pa. The hMSCs on Gtn-HPA-Tyr hydrogel with G' greater than 20,000 showed significantly up-regulated expressions of osteocalcin and runt-related transcription factor 2 (RUNX2) on both the gene and protein level, with the presence of alkaline phosphatase, and the evidence of calcium accumulation. These studies with the Gtn-HPA-Tyr hydrogel with G' greater than 20,000 collectively suggest the stimulation of the hMSCs into osteogenic differentiation, while these same observations were not found with the Gtn-HPA hydrogel with a G' of 13,500.

  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. 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)

  17. Synthesis of carboxymethylcellulose/acrylic acid hydrogels with superabsorbent properties by radiation-initiated crosslinking

    Science.gov (United States)

    Fekete, Tamás; Borsa, Judit; Takács, Erzsébet; Wojnárovits, László

    2016-07-01

    Superabsorbent hydrogels were prepared by gamma irradiation from aqueous solutions of carboxymethylcellulose (CMC) and acrylic acid (AAc) with varying CMC:AAc ratio. By partially replacing the CMC with AAc the gelation increased and led to a higher gel fraction and lower water uptake. Moreover, the gelation required significantly milder synthesis conditions. Decreasing both the dose and the solute concentration in the presence of AAc led to gels with higher gel fraction and higher degree of swelling compared to pure CMC gels. Increasing the AAc content up to 10% proved to be very effective, while very high AAc content (over 50%) hindered the gelation process.

  18. Production of endothelial cell-enclosing alginate-based hydrogel fibers with a cell adhesive surface through simultaneous cross-linking by horseradish peroxidase-catalyzed reaction in a hydrodynamic spinning process.

    Science.gov (United States)

    Liu, Yang; Sakai, Shinji; Taya, Masahito

    2012-09-01

    We developed an alginate-based hydrogel fiber enabling to enclose endothelial cells, degradable on-demand by alginate lyase, and having a cell adhesive surface. The hydrogel fiber was obtained by extruding an aqueous solution of 4% (w/v) alginate derivative possessing phenolic hydroxyl moieties (Alg-Ph) and horseradish peroxidase (HRP) into a flow of aqueous solution containing 0.3 mM H(2)O(2) and gelatin derivative possessing Ph moieties (Gelatin-Ph). In the process, cross-linking of Alg-Ph resulting in a hydrogel fiber and immobilization of Gelatin-Ph on the surface of the hydrogel fiber were simultaneously accomplished by an HRP-catalyzed cross-linking reaction between Ph moieties. The diameter of the hydrogel fiber and the quantity of immobilized Gelatin-Ph on the fiber were controllable by changing the flow rates of the solutions and the concentration of HRP in the Alg-Ph-containing solution, respectively. The viability of the human endothelial cells enclosed in the hydrogel fibers obtained by 10 s of flowing in the H(2)O(2)-containing solution was 87.1%. In addition, the cells harvested from the hydrogel fibers through degradation using alginate lyase grew on tissue culture dishes in the same fashion as the cells seeded by a conventional subculture protocol. Human smooth muscle cells adhered, grew and achieved confluence on the surface of the hydrogel fibers. By degrading the hydrogel fibers using alginate lyase, a tubular cell construct was successfully obtained.

  19. 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.

  20. 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

  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. 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.

  3. 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

  4. Viscoelastic characterization and modeling of gelation kinetics of injectable in situ cross-linkable poly(lactide-co-ethylene oxide-co-fumarate) hydrogels.

    Science.gov (United States)

    Sarvestani, Alireza S; He, Xuezhong; Jabbari, Esmaiel

    2007-02-01

    Cell transplantation by injection of biodegradable hydrogels is a recently developed strategy for the treatment of degenerated tissues. A cell carrier should be cytocompatible, have suitable working time and rheological properties for injection, and harden in situ to attain dimensional stability and the desired mechanical strength. Hydrophilic macromer/cross-linker polymerizing systems, due to the relatively high molecular weight of the macromer and its inability to cross the cell membrane, are very attractive as injectable cell carriers. The objective of this research was to determine the effects of cross-linker, initiator, and accelerator concentrations on the gelation kinetics and ultimate modulus of a biodegradable, in situ cross-linkable poly(lactide-co-ethylene oxide-co-fumarate) (PLEOF) macromer. The in situ polymerizing mixture consisted of PLEOF macromer, methylene bisacrylamide cross-linker, and a neutral redox initiation system of ammonium persulfate initiator and tetramethylethylenediamine accelerator. Measurement of the time evolution of the viscoelastic properties of the network during the sol-gel transition showed the important influence of each component on the gel time and stiffness of the hydrogels. A kinetic model was developed to predict the modulus as a function of composition. Model predictions were consistent with most of the experimental findings. The values of the storage and loss moduli at the gel point were found to be approximately equal for samples with equal PLEOF concentrations, resulting in a simple method to predict the gelation time based on the Winter--Chambon criterion, with the use of the proposed kinetic model. The results of this study can be coupled with component cytocompatibility measurements to predict the effect of composition on the viability of the cells encapsulated in the hydrogel matrix. PMID:17253761

  5. 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

  6. Preparation of Well-Defined Propargyl-Terminated Tetra-Arm Poly(N-isopropylacrylamides and Their Click Hydrogels Crosslinked with β-cyclodextrin

    Directory of Open Access Journals (Sweden)

    Jianquan Wang

    2016-03-01

    Full Text Available As an important class of reversible deactivation radical polymerization (RDRP, reversible addition fragmentation chain transfer (RAFT polymerization has attracted great attention attributed to its facile and flexible features to prepare well-defined polymers with different complex structures. In addition, the combination of RAFT with click chemistry provides more effective strategies to fabricate advanced functional materials. In this work, a series of temperature responsive tetra-arm telechelic poly(N-isopropylacrylamides (PNIPAs with propargyl end groups were prepared for the first time through RAFT and subsequent aminolysis/Michael addition modification. The temperature sensitivities of their aqueous solutions were researched via turbidity measurement. It was found that the phase transition temperature of obtained PNIPAs increased with their molecular weights ascribed to their distinctions in the hydrophobic/hydrophilic balance. Subsequently, β-cyclodextrin (β-CD functionalized with azide moieties was used to crosslink the prepared propargyl-terminated tetra-arm PNIPAs through click chemistry, fabricating corresponding hydrogels with thermoresponse. Similar to their precursors, the hydrogels demonstrated the same dependence of volume phase transition temperature (VPTT on their molecular weights. In addition, the incorporation of β-CD and the residual groups besides crosslinking may provide a platform for imparting additional functions such as inclusion and adsorption as well as further functionalization.

  7. Intra-articular delivery of sinomenium encapsulated by chitosan microspheres and photo-crosslinked GelMA hydrogel ameliorates osteoarthritis by effectively regulating autophagy.

    Science.gov (United States)

    Chen, Pengfei; Xia, Chen; Mei, Sheng; Wang, Jiying; Shan, Zhi; Lin, Xianfeng; Fan, Shunwu

    2016-03-01

    Reduced expression of autophagy regulators has been observed in pathological cartilage in humans and mice. The present study aimed to investigate the synergistic therapeutic effect of promotion of chondrocyte autophagy via exposure to sinomenium (SIN) encapsulated by chitosan microspheres (CM-SIN) and photo-crosslinked gelatin methacrylate (GelMA) hydrogel, with the goal of evaluating CM-SIN as a treatment for patients with osteoarthritis. First, we fabricated and characterized GelMA hydrogels and chitosan microspheres. Next, we measured the effect of SIN on cartilage matrix degradation induced by IL1-β in chondrocytes and an ex vivo model. SIN ameliorated the pathological changes induced by IL1-β at least partially through activation of autophagy. Moreover, we surgically induced osteoarthritis in mice, which were injected intra-articularly with CM-SIN and GelMA. Cartilage matrix degradation and chondrocyte autophagy were evaluated 4 and 8 weeks after surgery. Treatment with the combination of CM-SIN and GelMA retarded the progression of surgically induced OA. SIN ameliorated cartilage matrix degradation at least partially by inducing autophagy in vivo. Our results demonstrate that injection of the combination of GelMA hydrogel and CM-SIN could be a promising strategy for treating patients with osteoarthritis.

  8. 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.

  9. PRAGMATIC HYDROGELS

    Directory of Open Access Journals (Sweden)

    Patil S.A.

    2011-03-01

    Full Text Available 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 are presently under investigation as a delivery system for bioactive molecules as having similar physical properties as that of living tissue, which is due to their high water content, soft and rubbery consistency and low interfacial tension with water and biological fluids. Hydrogels are three-dimensional, hydrophilic, polymeric networks capable of imbibing large amounts of water or biological fluids. The networks are composed of homopolymers or copolymers, and are insoluble due to the presence of chemical crosslink (tie-points, junctions or physical crosslink, such as entanglements or crystallite. The latter provide the network structure and physical integrity. These hydrogels exhibit a thermodynamic compatibility with water which allows them to swell in aqueous media. The nature of the degradation product can be tailored by a rational and proper selection of building blocks. The soft and rubbery nature of hydrogels minimizes irritation to surrounding tissues. In general, hydrogels possess good biocompatibility and biodegradability.

  10. Synthesis and characterization of high performance superabsorbent hydrogels using bis[2-(methacryloyloxy)ethyl] phosphate as crosslinker

    OpenAIRE

    A. A. L. Goncalves; Fonseca, A. C.; I. G. P. Fabela; J. F. J. Coelho; Serra, A. C.

    2016-01-01

    Various superabsorbent polymers (SAPs) were synthesized by free radical copolymerization at 70°C using acrylic acid (AA), potassium acrylate (KA), N-isopropyl acrylamide (NIPAM) and sulfopropyl methacrylate potassium salt (SPM) as monomers, bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) as crosslinker and potassium persulfate (KPS) as initiator. The optimization of the synthesis led to the preparation of a SAP with very high water absorption ability, with a maximum swelling of 2618 g water/g ...

  11. 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

  12. 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

  13. Cyclodextrin Inclusion Polymers Forming Hydrogels

    Science.gov (United States)

    Li, Jun

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

  14. THERMAL-SENSITIVE BETA-CYCLODEXTRIN-CONTAINING POLY(N-ISOPROPYLACRYLAMIDE) HYDROGELS CROSSLINKED BY Si-O-Si BONDS -SYNTHESIS, CHARACTERIZATION AND PROLONGING IN VITRO RELEASE OF 5-FLUOROURACIL

    Institute of Scientific and Technical Information of China (English)

    Jian-tao Zhang; Shi-wen Huang; Ya-nan Xue; Ji Liu; Ren-xi Zhuo

    2005-01-01

    A series of novel p(N-isopropylacrylamide) (PNIPAM) hydrogels were synthesized by radical copolymerization of N-isopropylacrylamide (NIPAM) and 3-methacryloxypropyltrimethoxysilane (MPTMS). The copolymers were then crosslinked through hydrolysis of the siloxane in acetic acid/water mixed solvent. Beta-cyclodextrin (Beta-CD) was introduced into the polymeric networks by condensation of 3-glycidoxypropyltrimethoxysilane derived beta-cyclodextrin (KH560-beta-CD) with MPTMS under acidic condition. These gels were heterogeneous, porous and exhibited fast deswelling kinetics when the temperature was elevated to above lower critical solution temperature (LCST). The swelling ratios of the gels containing beta-CD at room temperature were higher than that of the normal PNIPAM hydrogel, which was caused by the lower crosslinking density in beta-CD contained gels. In comparison to that of the normal PNIPAM gel, the amount of loaded-drug in the hydrogel containing beta-CD was higher, and the release time of 5-fluorouracil (5-Fu) was prolonged, which was attributed to the formation of inclusion compounds between 5-Fu and beta-CD in gel network.

  15. Electrochemical characterization of hydrogels for biomimetic applications

    DEFF Research Database (Denmark)

    Peláez, L.; Romero, V.; Escalera, S.;

    2011-01-01

    ) or a photoinitiator (P) to encapsulate and stabilize biomimetic membranes for novel separation technologies or biosensor applications. In this paper, we have investigated the electrochemical properties of the hydrogels used for membrane encapsulation. Specifically, we studied the crosslinked hydrogels by using...... electrochemical impedance spectroscopy (EIS), and we demonstrated that chemically crosslinked hydrogels had lower values for the effective electrical resistance and higher values for the electrical capacitance compared with hydrogels with photoinitiated crosslinking. Transport numbers were obtained using......〉 and 〈Pw〉 values than PEG‐1000‐DMA‐P and PEG‐400‐DA‐P hydrogels. In conclusion, our results show that hydrogel electrochemical properties can be controlled by the choice of polymer and type of crosslinking used and that their water and salt permeability properties are congruent with the use of hydrogels...

  16. Rapid self-healing hydrogels

    Science.gov (United States)

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

    2012-01-01

    Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hydrogel network with flexible-pendant side chains carrying an optimal balance of hydrophilic and hydrophobic moieties that allows the side chains to mediate hydrogen bonds across the hydrogel interfaces with minimal steric hindrance and hydrophobic collapse. The self-healing reported here is rapid, occurring within seconds of the insertion of a crack into the hydrogel or juxtaposition of two separate hydrogel pieces. The healing is reversible and can be switched on and off via changes in pH, allowing external control over the healing process. Moreover, the hydrogels can sustain multiple cycles of healing and separation without compromising their mechanical properties and healing kinetics. Beyond revealing how secondary interactions could be harnessed to introduce new functions to chemically cross-linked polymeric systems, we also demonstrate various potential applications of such easy-to-synthesize, smart, self-healing hydrogels. PMID:22392977

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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)

  2. 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.

  3. Gelatin-based biomaterial engineering with anhydride-containing oligomeric cross-linkers.

    Science.gov (United States)

    Loth, Tina; Hötzel, Rudi; Kascholke, Christian; Anderegg, Ulf; Schulz-Siegmund, Michaela; Hacker, Michael C

    2014-06-01

    Chemically cross-linked gelatin hydrogels are versatile cell-adhesive hydrogel materials that have been established for a variety of biomedical applications. The most prominent cross-linker is glutaraldehyde, which, however, has been described to cause compatibility problems and loss of microscopic but relevant structural features. A recently developed oligomeric cross-linker that contains anhydride functionalities was evaluated as cross-linker for the fabrication of gelatin-based hydrogels and microparticles. In a fast curing reaction, hydrogels composed of gelatin and oligomeric cross-linker were fabricated with good conversion over a wide concentration range of constituents and with cross-linkers of different anhydride contents. Hydrogel properties, such as dry weight and mechanics, could be controlled by hydrogel composition and rheological properties correlated to elastic moduli from 1 to 10 kPa. The gels were shown to be cytocompatible and promoted cell adhesion. In soft formulations, cells migrated into the hydrogel bulk. Gelatin microparticles prepared by a standard water-in-oil emulsion technique were also treated with the novel oligomers, and cross-linking degrees matching those obtained with glutaraldehyde were obtained. At the same time, fewer interparticular cross-links were observed. Fluorescein-derivatized cross-linkers yielded labeled microparticles in a concentration-dependent manner. The oligomeric cross-linkers are presented as an efficient and possibly more functional and compatible alternative to glutaraldehyde. The engineered hydrogel materials hold potential for various biomedical applications.

  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. 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.

  9. Plasma polymerized hydrogel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tamirisa, Prabhakar A. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Koskinen, Jere [Institute of Paper Science and Technology, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Hess, Dennis W. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)]. E-mail: dennis.hess@chbe.gatech.edu

    2006-12-05

    Plasma polymerization was used to produce thermoresponsive hydrogel films of N-isopropylacrylamide (NIPAAm) in a single deposition step. Solvent free processing to produce laterally confined intelligent hydrogel films offers the potential for high volume production of micro-sensors/actuators. Through variation of reactor conditions such as deposition pressure and substrate temperature, it is possible to tailor and control chemical properties of the films such as crosslink density and thus swelling. Fabrication of hydrogel thin films with adequate crosslinks is critical to ensuring adhesion to substrates and stability in aqueous environments. Chemical bonding structures in plasma polymerized NIPAAm were studied using Fourier transform infrared spectroscopy and the thermoresponsive nature of plasma polymerized NIPAAm was confirmed through contact angle goniometry. A reversible temperature dependent contact angle change was observed.

  10. 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

  11. 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.

  12. Synthesis of interpenetrating network hydrogel from poly(acrylic acid-co-hydroxyethyl methacrylate) and sodium alginate: modeling and kinetics study for removal of synthetic dyes from water.

    Science.gov (United States)

    Mandal, Bidyadhar; Ray, Samit Kumar

    2013-10-15

    Several interpenetrating network (IPN) hydrogels were made by free radical in situ crosslink copolymerization of acrylic acid (AA) and hydroxy ethyl methacrylate in aqueous solution of sodium alginate. N,N'-methylenebisacrylamide (MBA) was used as comonomer crosslinker for making these crosslink hydrogels. All of these hydrogels were characterized by carboxylic content, FTIR, SEM, XRD, DTA-TGA and mechanical properties. Swelling, diffusion and network parameters of the hydrogels were studied. These hydrogels were used for adsorption of two important synthetic dyes, i.e. Congo red and methyl violet from water. Isotherms, kinetics and thermodynamics of dye adsorption by these hydrogels were also studied.

  13. 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

  14. 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.

  15. 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

  16. 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...

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

    Science.gov (United States)

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

    2013-01-10

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

  18. Extremely Stretchable and Fast Self-Healing Hydrogels.

    Science.gov (United States)

    Jeon, Insu; Cui, Jiaxi; Illeperuma, Widusha R K; Aizenberg, Joanna; Vlassak, Joost J

    2016-06-01

    Dynamic crosslinking of extremely stretchable hydrogels with rapid self-healing ability is described. Using this new strategy, the obtained hydrogels are able to elongate 100 times compared to their initial length and to completely self-heal within 30 s without external energy input. PMID:27061799

  19. HIGH-STRENGTH POLY(METH)ACRYLAMIDE COPOLYMER HYDROGELS

    NARCIS (Netherlands)

    WIERSMA, JA; SOS, M; PENNINGS, AJ

    1994-01-01

    The hydrogels described here are copolymers of acrylamide and methacrylamide highly cross-linked with piperazine diacrylamide or 4,7,10-trioxa-1,13-tridecanediamine diacrylamide by radical polymerisation in highly concentrated aqueous and aqueous gelatin solutions. The hydrogels were characterised b

  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. 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...

  2. 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...

  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. 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

  5. Cytocompatible, Photoreversible, and Self-Healing Hydrogels for Regulating Bone Marrow Stromal Cell Differentiation.

    Science.gov (United States)

    Yu, Lianlian; Xu, Kaige; Ge, Liangpeng; Wan, Wenbing; Darabi, Ali; Xing, Malcolm; Zhong, Wen

    2016-09-01

    Photo-crosslinking and self-healing have received considerable attention for the design of intelligent materials. A novel photostimulated, self-healing, and cytocompatible hydrogel system is reported. A coumarin methacrylate crosslinker is synthesized to modify the polyacrylamide-based hydrogels. With the [2+2] cyclo-addition of coumarin moieties, the hydrogels exhibit excellent self-healing capacity when they are exposed to light with wavelengths at 280 and 365 nm, respectively. To enhance cell compatibility, a poly (amidoamine) crosslinker is also synthesized. Variations in light exposure times and irradiation wavelengths are found to alter the self-healing property of the hydrogels. The hydrogels are shown to induce a regular cellular pattern. The hydrogels are used to regulate bone marrow stromal cells differentiation. The relative mRNA expressions are recorded to monitor the osteogenic differentiation of the cells. PMID:27280860

  6. Horseradish peroxidase-catalysed in situ-forming hydrogels for tissue-engineering applications.

    Science.gov (United States)

    Bae, Jin Woo; Choi, Jong Hoon; Lee, Yunki; Park, Ki Dong

    2015-11-01

    In situ-forming hydrogels are an attractive class of implantable biomaterials that are used for biomedical applications. These injectable hydrogels are versatile and provide a convenient platform for delivering cells and drugs via minimally invasive surgery. Although several crosslinking methods for preparing in situ forming hydrogels have been developed over the past two decades, most hydrogels are not sufficiently versatile for use in a wide variety of tissue-engineering applications. In recent years, enzyme-catalysed crosslinking approaches have been emerged as a new approach for developing in situ-forming hydrogels. In particular, the horseradish peroxidase (HRP)-catalysed crosslinking approach has received increasing interest, due to its highly improved and tunable capacity to obtain hydrogels with desirable properties. The HRP-catalysed crosslinking reaction immediately occurs upon mixing phenol-rich polymers with HRP and hydrogen peroxide (H2O2) in aqueous media. Based on this unique gel-forming feature, recent studies have shown that various properties of formed hydrogels, such as gelation time, stiffness and degradation rate, can be easily manipulated by varying the concentrations of HRP and H2O2. In this review, we outline the versatile properties of HRP-catalysed in situ-forming hydrogels, with a brief introduction to the crosslinking mechanisms involved. In addition, the recent biomedical applications of HRP-catalysed in situ-forming hydrogels for tissue regeneration are described.

  7. 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

  8. Rapid response of thermo-sensitive hydrogels with porous structures

    Science.gov (United States)

    Maeda, Shingo; Kato, Terukazu; Kogure, Hikaru; Hosoya, Naoki

    2015-04-01

    Poly(N-isopropylacrylamide)(PNIPAAm) hydrogel is thermo-sensitive, and undergoes a volume phase transition from a swollen state to a shrunken state. Typically, after immersing poly(N-isopropylacrylamide) hydrogels into hot water above the critical temperature, they undergo a two-step shrinking process, which leads to very slow dynamics. However, potential applications, including soft actuators, drug delivery systems, and cell cultures, demand a quick response. Herein, we synthesize chemically crosslinked PNIPAAm porous hydrogels made of nanofiber mats. Our hydrogels rapidly shrink without the two-step shrinking. The response of this porous gel is over 100 times faster than that of the typical gel.

  9. 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 ...

  10. 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.

  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. 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

  13. Deformation-induced damage and recovery in model hydrogels - A molecular dynamics simulation

    Science.gov (United States)

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

    2016-09-01

    Using molecular dynamics simulation of a model hybrid cross-link hydrogel, we investigate the network damage evolution and the related structure transformations. We model the hydrogel structure as a network-connected assembly of crosslinked clusters whereby deformation-induced damage is considered along with network recovery. The two principal mechanisms involved in hydrogel recovery from deformation include segment hops of the building structure units (segments) between clusters and cluster shape modification. These mechanisms act either instantaneously, or with a certain time delay after the onset of deformation. By elucidating the conditions under which one of the mechanisms prevails, one may design hydrogel materials with a desired response to deformation.

  14. 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.

  15. Hydrogels for in situ encapsulation of biomimetic membrane arrays

    DEFF Research Database (Denmark)

    Ibragimova, Sania; Jensen, Karin Bagger Stibius; Szewczykowski, Piotr Przemyslaw;

    2012-01-01

    Hydrogels are hydrophilic, porous polymer networks that can absorb up to thousands of times their own weight in water. They have many potential applications, one of which is the encapsulation of freestanding black lipid membranes (BLMs) for novel separation technologies or biosensor applications...... a chemical initiator or a photoinitiator. The hydrogels were studied with regards to volumetric stability, porosity, and water permeability. All hydrogels had pore sizes around 7 nm with volumetric changes >2% upon crosslinking. Photoinitiated hydrogels had a lower hydraulic water permeability compared...... to chemically initiated hydrogels; however, for all hydrogels the permeability was several-fold higher than the water permeability of conventional reverse osmosis (RO) membranes. Lifetimes of freestanding BLM arrays in gel precursor solutions were short compared to arrays formed in buffer. However, polymerizing...

  16. 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.

  17. On the development of multifunctional luminescent supramolecular hydrogel of gold and egg white

    Science.gov (United States)

    Patra, Sudeshna; Ravulapalli, Sathyavathi; Hahm, Myung Gwan; Tadi, Kiran Kumar; Narayanan, Tharangattu N.

    2016-10-01

    Highly stable, luminescent, and printable/paintable supramolecular egg white hydrogel-based surface enhanced Raman scattering (SERS) matrix is created by an in situ synthesis of gold clusters inside a luminescent egg white hydrogel (Au-Gel). The synthesis of stable luminescent egg-white-based hydrogel, where the hydrogel can act as a three dimensional (3D) matrix, using a simple cross-linking chemistry, has promising application in the biomedical field including in 3D cell culturing. Furthermore, this functional hydrogel is demonstrated for micromolar-level detection of Rhodamine 6G using the SERS technique, where Au-Gel is painted over a flexible cellulose pad.

  18. 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.

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

    Science.gov (United States)

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

    2011-10-15

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

  20. PVA/STMP based hydrogels as potential substitutes of human vitreous.

    Science.gov (United States)

    Leone, Gemma; Consumi, Marco; Aggravi, Marianna; Donati, Alessandro; Lamponi, Stefania; Magnani, Agnese

    2010-08-01

    PVA based hydrogels were synthesised using, as crosslinking agent, trisodium trimetaphosphate (STMP) to obtain potential substitutes for the vitreous body of the eye. The hydrogels, obtained using different amounts of STMP, were characterised by Infrared Spectroscopy which confirmed the successful occurrence of crosslinking reaction. The mechanical spectra of the fully hydrated samples confirmed covalently crosslinked systems (i.e. G' > G''). The rheological analysis pointed out that only one of the hydrogels (PVA STMP 8:1) showed a behaviour similar to that of human vitreous. The hydrogel was also subjected to injection through a small needle, a procedure that is essential in the use of vitreous substitutes. Further analysis in terms of light transmittance, water content measurements, diffusion coefficient and cytotoxicity confirmed the applicability of such a hydrogel as vitreous substitute. PMID:20499140

  1. Enhanced mechanical performance of biocompatible hemicelluloses-based hydrogel via chain extension.

    Science.gov (United States)

    Qi, Xian-Ming; Chen, Ge-Gu; Gong, Xiao-Dong; Fu, Gen-Que; Niu, Ya-Shuai; Bian, Jing; Peng, Feng; Sun, Run-Cang

    2016-01-01

    Hemicelluloses are widely used to prepare gel materials because of their renewability, biodegradability, and biocompatibility. Here, molecular chain extension of hemicelluloses was obtained in a two-step process. Composite hydrogels were prepared via free radical graft copolymerization of crosslinked quaternized hemicelluloses (CQH) and acrylic acid (AA) in the presence of crosslinking agent N,N'-methylenebisacrylamide (MBA). This chain extension strategy significantly improved the mechanical performance of the resulting hydrogels. The crosslinking density, compression modulus, and swelling capacities of hydrogels were tuned by changing the AA/CQH and MBA/CQH contents. Moreover, the biocompatibility test suggests that the hemicelluloses-based hydrogels exhibited no toxicity to cells and allowed cell growth. Taken together, these properties demonstrated that the composite hydrogels have potential applications in the fields of water absorbents, cell culture, and other functional biomaterials. PMID:27634095

  2. Enhanced mechanical performance of biocompatible hemicelluloses-based hydrogel via chain extension

    Science.gov (United States)

    Qi, Xian-Ming; Chen, Ge-Gu; Gong, Xiao-Dong; Fu, Gen-Que; Niu, Ya-Shuai; Bian, Jing; Peng, Feng; Sun, Run-Cang

    2016-01-01

    Hemicelluloses are widely used to prepare gel materials because of their renewability, biodegradability, and biocompatibility. Here, molecular chain extension of hemicelluloses was obtained in a two-step process. Composite hydrogels were prepared via free radical graft copolymerization of crosslinked quaternized hemicelluloses (CQH) and acrylic acid (AA) in the presence of crosslinking agent N,N’-methylenebisacrylamide (MBA). This chain extension strategy significantly improved the mechanical performance of the resulting hydrogels. The crosslinking density, compression modulus, and swelling capacities of hydrogels were tuned by changing the AA/CQH and MBA/CQH contents. Moreover, the biocompatibility test suggests that the hemicelluloses-based hydrogels exhibited no toxicity to cells and allowed cell growth. Taken together, these properties demonstrated that the composite hydrogels have potential applications in the fields of water absorbents, cell culture, and other functional biomaterials. PMID:27634095

  3. 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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2013-10-01

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

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

    Science.gov (United States)

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

    2015-06-01

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

  7. 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

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

    Directory of Open Access Journals (Sweden)

    Masanobu Chiku

    2011-09-01

    Full Text Available 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.

  9. 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...

  10. 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, ...

  11. 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 ...

  12. 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.

  13. 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...

  14. 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...

  15. 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...

  16. 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.

  17. Synthesis of hydrogel by radiation and its application as wound dressing

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-06-01

    Synthesis of hydrogel with no contamination has been attempted using radiological techniques aiming at its application to medical substances. In this report, radiation crosslinking of polyethyleneoxide (PEO), polyvinylalcohol (PVA) and polyvinylpyrrolidone (PVP) as well as application of hydrogels produced from these polymers were described. Generally, these hydrogels have been synthesized through radiation-induced crosslinking. However, crosslinking occurred easily by radiation exposure of a melt phase polymer like PEO, of which molecular movement is active, resulting in production of hydrogel of high purity. Either of heat resistance or gel strength of hydrogel was low, because those were full of water. When molecular chain was slightly fixed through acetalation before irradiation as seen in the synthesis from PVA, much smooth crosslinking occurred, leading to production of a hydrogel superior in strength. Regarding the blend hydrogel produced from PVP and carrageenan, gel strength was markedly increased by graft polymerization of PVP chain and the carrageenan chain was degraded by irradiation. Present results suggested that multifunctional hydrogels could be produced by complex irradiation. (M.N.)

  18. 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.

  19. Resilin-PEG Hybrid Hydrogels Yield Degradable Elastomeric Scaffolds with Heterogeneous Microstructure.

    Science.gov (United States)

    McGann, Christopher L; Akins, Robert E; Kiick, Kristi L

    2016-01-11

    Hydrogels derived from resilin-like polypeptides (RLPs) have shown outstanding mechanical resilience and cytocompatibility; expanding the versatility of RLP-based materials via conjugation with other polypeptides and polymers would offer great promise in the design of a range of materials. Here, we present an investigation of the biochemical and mechanical properties of hybrid hydrogels composed of a recombinant RLP and a multiarm PEG macromer. These hybrid hydrogels can be rapidly cross-linked through a Michael-type addition reaction between the thiols of cysteine residues on the RLP and vinyl sulfone groups on the multiarm PEG. Oscillatory rheology and tensile testing confirmed the formation of elastomeric hydrogels with mechanical resilience comparable to aortic elastin; hydrogel stiffness was easily modulated through the cross-linking ratio. Macromolecular phase separation of the RLP-PEG hydrogels offers the unique advantage of imparting a heterogeneous microstructure, which can be used to localize cells, through simple mixing and cross-linking. Assessment of degradation of the RLP by matrix metalloproteinases (MMPs) illustrated the specific proteolysis of the polypeptide in both its soluble form and when cross-linked into hydrogels. Finally, the successful encapsulation and viable three-dimensional culture of human mesenchymal stem cells (hMSCs) demonstrated the cytocompatibility of the RLP-PEG gels. Overall, the cytocompatibility, elastomeric mechanical properties, microheterogeneity, and degradability of the RLP-PEG hybrid hydrogels offer a suite of promising properties for the development of cell-instructive, structured tissue engineering scaffolds.

  20. Polymer Micelles Laden Hydrogel Contact Lenses for Ophthalmic Drug Delivery.

    Science.gov (United States)

    Hu, Xiaohong; Tan, Huaping; Chen, Pin; Wang, Xin; Pang, Juan

    2016-06-01

    Hydrogel contact lens is an attractive drug carrier for the delivery of ophthalmic drugs. But limited drug loading capacity and burst release restricted its application in this field. Polymer micelle laden hydrogel contact lenses were designed for ophthalmic drug delivery in the work. β-CD/PAA/PEG ternary system was chosen to form polymer micelle. The micelle size could be adjusted by β-CD content and PAA/PEG concentration. The zeta potential of micelle was irrelevant to β-CD content, but influenced by PAA/PEG concentration. The absorbed drug concentration in micelle solution depended on both β-CD content and PAA/PEG concentration. Polymer micelle laden hydrogels were obtained by radical polymerization in situ. The transparency of polymer micelle laden hydrogel declined with PAA/PEG concentration increasing. The equilibrium water content and water loss showed that polymer micelle laden hydrogel with higher PAA/PEG concentration was in a higher swollen state. The dynamic viscoelastic properties howed that all polymer micelle laden hydrogels had some characteristics of crosslinked elastomers. The surface structure of freeze dried composite hydrogels was different from freeze dried pure hydrogel. The drug loading and releasing behaviors were detected to evaluate the drug loading and releasing capacity of hydrogels using orfloxacin and puerarin as model drugs. The results indicated the polymer micelle in hydrogel could hold or help to hold some ophthalmic drugs, and slow down orfloxacin release speed or keep puerarin stably stay for a time in hydrogels. In the end, it was found that the transparency of composite hydrogel became better after the hydrogel had been immersed in PBS for several weeks.

  1. Improving the stability of chitosan-gelatin-based hydrogels for cell delivery using transglutaminase and controlled release of doxycycline.

    Science.gov (United States)

    Tormos, Christian J; Abraham, Carol; Madihally, Sundararajan V

    2015-12-01

    Although local cell delivery is an option to repair tissues, particularly using chitosan-based hydrogels, significant attrition of injected cells prior to engraftment has been a problem. To address this problem, we explored the possibility of stabilizing the chitosan-gelatin (CG) injectable hydrogels using (1) controlled release of doxycycline (DOX) to prevent premature degradation due to increased gelatinase activity (MMP-2 and MMP-9), and (2) transglutaminase (TG) to in situ cross-link gelatin to improve the mechanical stability. We prepared DOX-loaded PLGA nanoparticles, loaded into the CG hydrogels, measured DOX release for 5 days, and modeled using a single-compartmental assumption. Next, we assessed the influence of TG and DOX on hydrogel compression properties by incubating hydrogels for 7 days in PBS. We evaluated the effect of these changes on retention of fibroblasts and alterations in MMP-2/MMP-9 activity by seeding 500,000 fibroblasts for 5 days. These results showed that 90 % of DOX released from cross-linked CG hydrogels after 4 days, unlike CG hydrogels where 90 % of DOX was released within the first day. Addition of TG enhanced the CG hydrogel stability significantly. More than 60 % of seeded fibroblasts were recovered from the CG-TG hydrogels at day 5, unlike 40 % recovered from CG-hydrogels. Inhibition of MMP-2/MMP-9 were observed. In summary, controlled release of DOX from CG hydrogels cross-linked with TG shows a significant potential as a carrier for cell delivery.

  2. STUDY ON ASPIRIN-MAA HYDROGEL MIP SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The controlled 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 crosslinking 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.

  3. 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

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

    Science.gov (United States)

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

    2012-06-01

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

  5. 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)

  6. 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)

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

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

    Science.gov (United States)

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

    2016-01-20

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

  15. 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)

  16. 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)

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

    Science.gov (United States)

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

    2008-06-01

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

  18. 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.

  19. 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

  20. 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.

  1. 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)

  2. 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

  3. Viscoelasticity of hyaluronic acid-gelatin hydrogels for vocal fold tissue engineering.

    Science.gov (United States)

    Kazemirad, Siavash; Heris, Hossein K; Mongeau, Luc

    2016-02-01

    Crosslinked injectable hyaluronic acid (HA)-gelatin (Ge) hydrogels have remarkable viscoelastic and biological properties for vocal fold tissue engineering. Patient-specific tuning of the viscoelastic properties of this injectable biomaterial could improve tissue regeneration. The frequency-dependent viscoelasticity of crosslinked HA-Ge hydrogels was measured as a function of the concentration of HA, Ge, and crosslinker. Synthetic extracellular matrix hydrogels were fabricated using thiol-modified HA and Ge, and crosslinked by poly(ethylene glycol) diacrylate. A recently developed characterization method based on Rayleigh wave propagation was used to quantify the frequency-dependent viscoelastic properties of these hydrogels, including shear storage and loss moduli, over a broad frequency range; that is, from 40 to 4000 Hz. The viscoelastic properties of the hydrogels increased with frequency. The storage and loss moduli values and the rate of increase with frequency varied with the concentrations of the constituents. The range of the viscoelastic properties of the hydrogels was within that of human vocal fold tissue obtained from in vivo and ex vivo measurements. Frequency-dependent parametric relations were obtained using a linear least-squares regression. The results are useful to better fine-tune the storage and loss moduli of HA-Ge hydrogels by varying the concentrations of the constituents for use in patient-specific treatments.

  4. Synthesis and characterization of antimicrobial crosslinked carboxymethyl chitosan nanoparticles loaded with silver.

    Science.gov (United States)

    Mohamed, Riham R; Sabaa, Magdy W

    2014-08-01

    Carboxymethyl chitosan (CMCh)-silver nanoparticle (Ag) hydrogels with high antibacterial activity against three Gram +ve bacteria (Staphylococcus aureus, Bacillus subtilis and Streptococcus faecalis), three Gram -ve bacteria (Escherichia coli, Pseudomonas aeruginosa and Neisseria gonorrhoeae) and a Candida albicans fungus were prepared. The in situ preparation reaction involved crosslinking of CMCh with epichlorohydrin in alkaline medium containing silver nitrate to yield silver nanoparticles loaded CMCh hydrogel giving pale brown or darker hydrogels when the silver content increases. FTIR spectroscopy, SEM and TEM were done for the prepared hydrogels. Silver nanoparticles hydrogels exhibited higher antimicrobial activity than virgin CMCh. TEM analysis showed the small size of the prepared hydrogels to be in the range of 9-16nm in size.

  5. 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.

  6. 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)

  7. 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.

  8. 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

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

    Science.gov (United States)

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

    2016-02-10

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

  10. Three-dimensional bioprinting of complex cell laden alginate hydrogel structures.

    Science.gov (United States)

    Tabriz, Atabak Ghanizadeh; Hermida, Miguel A; Leslie, Nicholas R; Shu, Wenmiao

    2015-12-21

    Different bioprinting techniques have been used to produce cell-laden alginate hydrogel structures, however these approaches have been limited to 2D or simple three-dimension (3D) structures. In this study, a new extrusion based bioprinting technique was developed to produce more complex alginate hydrogel structures. This was achieved by dividing the alginate hydrogel cross-linking process into three stages: primary calcium ion cross-linking for printability of the gel, secondary calcium cross-linking for rigidity of the alginate hydrogel immediately after printing and tertiary barium ion cross-linking for long-term stability of the alginate hydrogel in culture medium. Simple 3D structures including tubes were first printed to ensure the feasibility of the bioprinting technique and then complex 3D structures such as branched vascular structures were successfully printed. The static stiffness of the alginate hydrogel after printing was 20.18 ± 1.62 KPa which was rigid enough to sustain the integrity of the complex 3D alginate hydrogel structure during the printing. The addition of 60 mM barium chloride was found to significantly extend the stability of the cross-linked alginate hydrogel from 3 d to beyond 11 d without compromising the cellular viability. The results based on cell bioprinting suggested that viability of U87-MG cells was 93 ± 0.9% immediately after bioprinting and cell viability maintained above 88% ± 4.3% in the alginate hydrogel over the period of 11 d.

  11. 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

  12. 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...

  13. In situ forming hydrogels of hyaluronic acid and inulin derivatives for cartilage regeneration.

    Science.gov (United States)

    Palumbo, Fabio S; Fiorica, Calogero; Di Stefano, Mauro; Pitarresi, Giovanna; Gulino, Alessandro; Agnello, Stefano; Giammona, Gaetano

    2015-05-20

    An in situ forming hydrogel obtained by crosslinking of amino functionalized hyaluronic acid derivatives with divinylsulfone functionalized inulin (INU-DV) has been here designed and characterized. In particular two hyaluronic acid derivatives bearing respectively a pendant ethylenediamino (EDA) portion (HA-EDA) and both EDA and octadecyl pendant groups (HA-EDA-C18) were crosslinked through an azo-Michael reaction with INU-DV. Gelation time and consumption of DV portions have been evaluated on hydrogel obtained using HA-EDA and HA-EDA-C18 derivatives with a concentration of 3% w/v and a ratio 80/20 w/w respect to the crosslinker INU-DV. The presence of pendant C18 chains improves mechanical performances of hydrogels and decreases the susceptibility to hyaluronidase hydrolysis. Bovine chondrocytes, encapsulated during crosslinking, sufficiently survive and efficiently proliferate until 28 days of analysis.

  14. 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...

  15. 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)

  16. 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.

  17. 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

  18. 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.

  19. 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)

  20. 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.

  1. 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

  2. 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...

  3. 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.

  4. 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.

  5. Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties.

    Science.gov (United States)

    Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Silan, Coskun; Aktas, Nahit; Turk, Mustafa

    2016-01-01

    A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90°C for 2h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5°C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS(+) radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro.

  6. Superabsorbent polysaccharide hydrogels based on pullulan derivate as antibacterial release wound dressing.

    Science.gov (United States)

    Li, Huanan; Yang, Jing; Hu, Xiaona; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

    2011-07-01

    To accomplish ideal wound dressing, hydrogels based on a natural polysaccharide, pullulan were synthesized by chemical cross-linking. The tensile strengths of the hydrogel films (1 mm thick) were determined to range from 0.663 to 1.097 MPa in proportion to cross-linking degrees and water contents. The swelling study of the hydrogels in water showed remarkable water absorption property with swelling ratio up to 4000%, which provided the hydrogel with quick hemostatic ability and prevent the wound bed from accumulation of exudates. The water vapor transmission rate and water retention of the hydrogels were found to be in the range of 2213-3498 g/m²/day and 34.74-45.81% (after 6 days), indicating that the hydrogel can maintain a moist environment over wound bed, which could prevent the dehydration of the wound bed and prevent the scab formation. Biocompatibility test revealed that the hydrogels were not cytotoxic. The hydrogel could load antimicrobial agents and effectively suppress bacterial proliferation to protect the wound from bacterial invasion. These results suggest that the pullulan hydrogels prepared in this study may have high potential as new ideal wound-dressing materials.

  7. 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

  8. Hidrogéis superabsorventes a base de acetato de celulose modificado por dianidrido 3,3', 4,4' benzofenona tetracarboxílico (BTDA: síntese, caracterização e estudos físico-químicos de absorção Synthesis of hydrogels of cellulose acetate (AC cross-linked with 3,3', 4,4' benzophenonetetracarboxylic dianhydride (BTDA: characterization and adsorption physicochemical study

    Directory of Open Access Journals (Sweden)

    Vagner R. Botaro

    2009-01-01

    Full Text Available Este trabalho descreve as sínteses de hidrogéis superabsorventes a base de acetato de celulose (AC, com grau de substituição 2.5, reticulado com dianidrido 3, 3', 4, 4' benzofenona tetracarboxílico (BTDA. As caracterizações das matérias primas foram realizadas por análises térmicas (TG/DTG e espectroscopia na região do infravermelho (FTIR. O grau de substituição do acetato de celulose foi determinado por via úmida. A confirmação da reação de esterificação foi possível a partir da técnica de FTIR, espectroscopia UV-vis e análises térmicas (TG/DTG. A presença de poros no novo material foi analisada por microscopia eletrônica de varredura (MEV e porosimetria (BET. A influência da concentração de dianidrido no meio reacional foi investigada, bem como a influência do aumento no grau de reticulação no comportamento térmico do material. Foram obtidas isotermas de absorção de água em diferentes temperaturas para os hidrogéis com diferentes graus de reticulação. Os coeficientes de difusão dos géis foram determinados, juntamente com a energia de ativação para o processo de inchamento usando a equação de Arrhenius. A entalpia de mistura do sistema gel-água foi determinada pela medida da quantidade máxima de água absorvida no equilíbrio a diferentes temperaturas, empregando a equação de Gibbs/Helmholtz.This work describes the synthesis of hydrogels of cellulose acetate (AC, with a nominal degree of substitution DS = 2.5, cross-linked with 3,3',4,4' benzophenonetetracarboxylic dianhydride (BTDA. The raw materials were characterized by thermal analysis (TG/DTG and by Fourier transform infrared spectroscopy (FTIR. DS of cellulose acetate was determined by titration with a known amount of standard NaOH solution. Hydrogels of BTDA were synthesized with 0.5, 0.75 and 1.0 mol of BTDA/mol of AC. FTIR proved to be a suitable method to monitor the course of reactions and the progress of purification. UV

  9. Functional nucleic acid-based hydrogels for bioanalytical and biomedical applications.

    Science.gov (United States)

    Li, Juan; Mo, Liuting; Lu, Chun-Hua; Fu, Ting; Yang, Huang-Hao; Tan, Weihong

    2016-03-01

    Hydrogels are crosslinked hydrophilic polymers that can absorb a large amount of water. By their hydrophilic, biocompatible and highly tunable nature, hydrogels can be tailored for applications in bioanalysis and biomedicine. Of particular interest are DNA-based hydrogels owing to the unique features of nucleic acids. Since the discovery of the DNA double helical structure, interest in DNA has expanded beyond its genetic role to applications in nanotechnology and materials science. In particular, DNA-based hydrogels present such remarkable features as stability, flexibility, precise programmability, stimuli-responsive DNA conformations, facile synthesis and modification. Moreover, functional nucleic acids (FNAs) have allowed the construction of hydrogels based on aptamers, DNAzymes, i-motif nanostructures, siRNAs and CpG oligodeoxynucleotides to provide additional molecular recognition, catalytic activities and therapeutic potential, making them key players in biological analysis and biomedical applications. To date, a variety of applications have been demonstrated with FNA-based hydrogels, including biosensing, environmental analysis, controlled drug release, cell adhesion and targeted cancer therapy. In this review, we focus on advances in the development of FNA-based hydrogels, which have fully incorporated both the unique features of FNAs and DNA-based hydrogels. We first introduce different strategies for constructing DNA-based hydrogels. Subsequently, various types of FNAs and the most recent developments of FNA-based hydrogels for bioanalytical and biomedical applications are described with some selected examples. Finally, the review provides an insight into the remaining challenges and future perspectives of FNA-based hydrogels.

  10. 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

  11. Weak hydrogen bonding yields rigid, tough, and elastic hydrogels

    Science.gov (United States)

    Sheiko, Sergei; Hu, Xiaobo; Vatankhah-Varnosfaderani, Mohammad; Zhou, Jing; Li, Qiaoxi; Dobrynin, Andrey

    Unlike living tissues, synthetic hydrogels are inherently soft and brittle, particularly when built of hydrogen bonds. It remains challenging to design hydrogels that combine high rigidity, strength at break, extensibility, high elasticity. Through free-radical copolymerization of N , N -dimethylacrylamide and methacrylic acid, we have designed a network system based on tunable composition of covalent bonds (permanent cross-links) and hydrogen bonds (sacrificial and recoverable crosslinks) with the following rationale: 1) Maintain a high total number of cross-links to ensure high modulus; 2) Introduce a high fraction of H-bonding to ensure high energy dissipation; and 3) Incorporate a small fraction of permanent cross-links to ensure shape control. By tuning the chemical composition and microstructure we have obtained materials with superb mechanical properties. The hydrogels contain 70 wt% water (similar to living cartilage, skin, and ligaments), while display modulus of 28 MPa, strength of 2 MPa, fracture energy of 9300 J .m-2, extensibility of 800%, excellent fatigue-resistance, and great elasticity allowing for complete and fast strain recovery. The results agreed with theoretical predictions for modulus relaxation of dual networks with dynamic and permanent crosslinks. We gratefully acknowledge funding from the National Science Foundation (DMR 1122483, DMR 1407645, and DMR 1436201).

  12. 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...

  13. 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.

  14. 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.

  15. Spatially controlled bacterial adhesion using surface-patterned poly(ethylene glycol) hydrogels.

    Science.gov (United States)

    Krsko, Peter; Kaplan, Jeffrey B; Libera, Matthew

    2009-02-01

    We constructed surface-patterned hydrogels using low-energy focused electron beams to locally crosslink poly(ethylene glycol) (PEG) thin films on silanized glass substrates. Derived from electron-beam lithography, this technique was used to create patterned hydrogels with well-defined spatial positions and degrees of swelling. We found that cells of the bacterium Staphylococcus epidermidis adhered to and grew on the silanized glass substrates. These cells did not, however, adhere to surfaces covered by high-swelling lightly crosslinked PEG hydrogels. This finding is consistent with the cell-repulsiveness generally attributed to PEGylated surfaces. In contrast, S. epidermidis cells did adhere to surfaces covered by low-swelling highly crosslinked hydrogels. By creating precise patterns of repulsive hydrogels combined with adhesive hydrogels or with exposed glass substrate, we were able to spatially control the adhesion of S. epidermidis. Significantly, adhesive areas small enough to trap single bacterial cells could be fabricated. The results suggest that the lateral confinement imposed by cell-repulsive hydrogels hindered the cell proliferation and development into larger bacterial colonies.

  16. Antimicrobial chitosan-PVA hydrogel as a nanoreactor and immobilizing matrix for silver nanoparticles

    Science.gov (United States)

    Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna

    2012-09-01

    Hydrogels are water-insoluble crosslinked hydrophilic networks capable of retaining a large amount of water. The present work aimed to develop a novel chitosan-PVA-based hydrogel which could behave both as a nanoreactor and an immobilizing matrix for silver nanoparticles (AgNPs) with promising antibacterial applications. The hydrogel containing AgNPs were prepared by repeated freeze-thaw treatment using varying amounts of the crosslinker, followed by in situ reduction with sodium borohydride as a reducing agent. Characterization studies established that the hydrogel provides a controlled and uniform distribution of nanoparticles within the polymeric network without addition of any further stabilizer. The average particle size was found to be 13 nm with size distribution from 8 to 21 nm as per HR-TEM studies. Swelling studies confirmed that higher amount of crosslinker and silver incorporation inside the gel matrices significantly enhanced the porosity and chain entanglement of the polymeric species of the hydrogel, respectively. The AgNP-hydrogel exhibited good antibacterial activity and was found to cause significant reduction in microbial growth ( Escherichia coli) in 12 h while such activity was not observed for the hydrogel without AgNPs.

  17. Synthesis, characterization and applications of N-quaternized chitosan/poly(vinyl alcohol) hydrogels.

    Science.gov (United States)

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

    2015-09-01

    Hydrogels composed of N-quaternized chitosan (NQC) and poly(vinyl alcohol) (PVA) in different weight ratios (1:3), (1:1) and (3:1) chemically crosslinked by glutaraldehyde in different weight ratios – 1.0 and 5.0% – have been prepared. The prepared hydrogels were characterized via several analysis tools such as: Fourier transform IR (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). Different applications have been done on NQC/PVA hydrogels including; metal ions uptake, swellability in different buffer solutions (pH: 4, 7 and 9), swellability and degradation studies in simulated body fluid (SBF) solutions and antimicrobial activity towards bacteria and fungi. The results indicated that crosslinked NQC/PVA hydrogels with glutaraldehyde (GA) are more thermallystable than non crosslinked hydrogels, NQC/PVA hydrogels swell highly in different buffer solutions as PVA content increases and the antimicrobial activity of NQC/PVA hydrogels is higher than NQC itself.

  18. 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

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

    Science.gov (United States)

    Klinkajon, Wimonwan; Supaphol, Pitt

    2014-08-01

    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) (Cu(2+)) sulfate solution. In the second step, the films were further cross-linked in a corresponding Cu(2+) sulfate solution using a dipping method to further improve their dimensional stability. Alginate solution (at 2%w/v) and Cu(2+) sulfate solution (at 2%w/v) in acetate buffer at a low pH provided soft films with excellent swelling behavior. An increase in either Cu(2+) 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 Cu(2+) 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.

  20. 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)

  1. 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

  2. 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

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

    Science.gov (United States)

    Xu, Kun; Tan, Ying; Chen, Qiang; An, Huiyong; Li, Wenbo; Dong, Lisong; Wang, Pixin

    2010-05-15

    Series of hydrophilic core-shell microgels with cross-linked poly(N-isopropylacrylamide) (PNIPAAm) as core and poly(vinyl amine) (PVAm) as shell are synthesized via surfactant-free emulsion polymerization. Then, the microgels are treated with a small amount of potassium persulfate (KPS) to generate free radicals on the amine nitrogens of PVAm, which subsequently initiate the graft copolymerization of acrylic acid (AA), acryloyloxyethyl trimethyl ammonium chloride (DAC), and acrylamide (AAm) onto microgels to prepare multi-responsive composite hydrogels. The composite hydrogels consist of cross-linked ungrafted polyampholyte chains as the first network and microgels with grafted polyampholyte chains as graft point and second network and show surprising mechanical strength and rapid response rate. The investigation shows the compress strength of composite hydrogels is up to 17-30 MPa, which is 60-100 times higher than that of the hydrogel matrix. The composite hydrogel shows reversible switch of transmittance when traveling the lowest critical temperature (LCST) of microgels. When the composite hydrogel swollen in pH 2.86 solution at ambient condition is immersed into the pH 7.00 solution at 45 °C, a rapid dynamic shrinking can be observed. And the character time (τ) of shrinking dynamic of composite hydrogel is 251.9 min, which is less than that of hydrogel matrix (τ=2273.7 min). PMID:20152987

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

    Directory of Open Access Journals (Sweden)

    Rozaini Mohd Zohdi

    2012-01-01

    Full Text Available 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 hydrogel dressings significantly enhanced (P<0.05 wound closure and accelerated the rate of re-epithelialization as compared to control hydrogel and OpSite film dressing. A significant decrease in inflammatory response was observed in honey hydrogel treated wounds as early as 7 days after burn (P<0.05. Semiquantitative analysis using RT-PCR revealed that treatment with honey hydrogel significantly (P<0.05 suppressed the expression of proinflammatory cytokines (IL-1α, IL-1β, and IL-6. The present study substantiates the potential efficacy of honey hydrogel dressings in accelerating burn wound healing.

  5. Recent Advances in Dendritic Macromonomers for Hydrogel Formation and Their Medical Applications.

    Science.gov (United States)

    Ghobril, Cynthia; Rodriguez, Edward K; Nazarian, Ara; Grinstaff, Mark W

    2016-04-11

    Hydrogels represent one of the most important classes of biomaterials and are of interest for various medical applications including wound repair, tissue engineering, and drug release. Hydrogels possess tunable mechanical properties, biocompatibility, nontoxicity, and similarity to natural soft tissues. The need for hydrogels with specific properties, based on the design requirements of the in vitro, in vivo, or clinical application, motivates researchers to develop new synthetic approaches and cross-linking methodologies to form novel hydrogels with unique properties. The use of dendritic macromonomers represents one elegant strategy for the formation of hydrogels with specific properties. Specifically, the uniformity of dendrimers combined with the control of their size, architecture, density, and surface groups make them promising cross-linkers for hydrogel formation. Over the last two decades, a large variety of dendritic-based hydrogels are reported for their potential use in the clinic. This review describes the state of the art with these different dendritic hydrogel formulations including their design requirements, the synthetic routes, the measurement and determination of their properties, the evaluation of their in vitro and in vivo performances, and future perspectives.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. Alginate-hyaluronan composite hydrogels accelerate wound healing process.

    Science.gov (United States)

    Catanzano, O; D'Esposito, V; Acierno, S; Ambrosio, M R; De Caro, C; Avagliano, C; Russo, P; Russo, R; Miro, A; Ungaro, F; Calignano, A; Formisano, P; Quaglia, F

    2015-10-20

    In this paper we propose polysaccharide hydrogels combining alginate (ALG) and hyaluronan (HA) as biofunctional platform for dermal wound repair. Hydrogels produced by internal gelation were homogeneous and easy to handle. Rheological evaluation of gelation kinetics of ALG/HA mixtures at different ratios allowed understanding the HA effect on ALG cross-linking process. Disk-shaped hydrogels, at different ALG/HA ratio, were characterized for morphology, homogeneity and mechanical properties. Results suggest that, although the presence of HA does significantly slow down gelation kinetics, the concentration of cross-links reached at the end of gelation is scarcely affected. The in vitro activity of ALG/HA dressings was tested on adipose derived multipotent adult stem cells (Ad-MSC) and an immortalized keratinocyte cell line (HaCaT). Hydrogels did not interfere with cell viability in both cells lines, but significantly promoted gap closure in a scratch assay at early (1 day) and late (5 days) stages as compared to hydrogels made of ALG alone (phydrogels significantly promoted wound closure as compared to ALG ones (phydrogel can be a versatile strategy to promote wound healing that can be easily translated in a clinical setting.

  11. Improvement of mechanical properties of hydrogel by irradiation of polymers in aqueous solution with {kappa}-carrageenan

    Energy Technology Data Exchange (ETDEWEB)

    Makuuchi, K.; Yoshii, F. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Aranilla, C.T. [Philippine Nuclear Research Institute, Diliman, Quezon (Philippines); Zhai, M. [Department of Technical Physics, Peking Univ., Beijing (China)

    2000-03-01

    Predominate radiation reaction of {kappa}-carrageenan (KC) hydrogel is the main chain scission of KC. The gel strength of KC hydrogel decreased with increasing irradiation dose. However, KC was found to enhances the radiation crosslinking of synthetic water-soluble polymer (SWSP) such as poly(ethylene oxide) (PEO) and poly(N-vinylpyrolidone) (PVP) in aqueous solution. The gel strength of SWSP hydrogel increased with increasing dose when KC was blended. Probably the radiation degraded KC radicals are recombined with radicals of PVP and PEO. The hydrogel thus prepared absorbs huge amounts of water due to the presence of strong hydrophilic -OSO{sub 3}{sup -} groups in KC. (author)

  12. 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

  13. 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.

  14. 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...

  15. 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.

  16. 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

  17. 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...

  18. 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...

  19. 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.

  20. 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

  1. Radiation synthesis of superabsorbent CMC based hydrogels for agriculture applications

    Energy Technology Data Exchange (ETDEWEB)

    Raafat, Amany I., E-mail: ismaelraafat_a@hotmail.com [Polymer Chemistry Department, National Center for Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo (Egypt); Eid, Mona; El-Arnaouty, Magda B. [Polymer Chemistry Department, National Center for Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo (Egypt)

    2012-07-15

    A series of superabsorbent hydrogel based on carboxymethylcellulose (CMC) and polyvinylpyrrolidone (PVP) crosslinked with gamma irradiation have been proposed for agriculture application. The effect of preparation conditions such as feed solution composition and absorbed irradiation dose on the gelation and swelling degree was evaluated. The structure and the morphology of the superabsorbent CMC/PVP hydrogel were characterized using Fourier transform infrared spectroscopy technique (FTIR), and scanning electron microscope (SEM). Effect of ionic strength and cationic and anionic kinds on the swelling behavior of the obtained hydrogel was investigated. Urea as an agrochemical model was loaded onto the obtained hydrogel to provide nitrogen (N) nutrients. The water retention capability and the urea release behavior of the CMC/PVP hydrogels were investigated. It was found that, the obtained CMC/PVP hydrogels have good swelling degree that greatly affected by its composition and absorbed dose. The swelling was also extremely sensitive to the ionic strength and cationic kind. Owing to its considerable slow urea release, good water retention capacity, being economical, and environment-friendly, it might be useful for its application in agriculture field.

  2. Engineering Protein Hydrogels Using SpyCatcher-SpyTag Chemistry.

    Science.gov (United States)

    Gao, Xiaoye; Fang, Jie; Xue, Bin; Fu, Linglan; Li, Hongbin

    2016-09-12

    Constructing hydrogels from engineered proteins has attracted significant attention within the material sciences, owing to their myriad potential applications in biomedical engineering. Developing efficient methods to cross-link tailored protein building blocks into hydrogels with desirable mechanical, physical, and functional properties is of paramount importance. By making use of the recently developed SpyCatcher-SpyTag chemistry, we successfully engineered protein hydrogels on the basis of engineered tandem modular elastomeric proteins. Our resultant protein hydrogels are soft but stable, and show excellent biocompatibility. As the first step, we tested the use of these hydrogels as a drug carrier, as well as in encapsulating human lung fibroblast cells. Our results demonstrate the robustness of the SpyCatcher-SpyTag chemistry, even when the SpyTag (or SpyCatcher) is flanked by folded globular domains. These results demonstrate that SpyCatcher-SpyTag chemistry can be used to engineer protein hydrogels from tandem modular elastomeric proteins that can find applications in tissue engineering, in fundamental mechano-biological studies, and as a controlled drug release vehicle.

  3. 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

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

    Directory of Open Access Journals (Sweden)

    Carlos W. de Q. Brito

    2013-01-01

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

  5. 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

  6. 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.

  7. Mechanical properties and failure analysis of visible light crosslinked alginate-based tissue sealants.

    Science.gov (United States)

    Charron, Patrick N; Fenn, Spencer L; Poniz, Alex; Oldinski, Rachael A

    2016-06-01

    Moderate to weak mechanical properties limit the use of naturally-derived tissue sealants for dynamic medical applications, e.g., sealing a lung leak. To overcome these limitations, we developed visible-light crosslinked alginate-based hydrogels, as either non-adhesive methacrylated alginate (Alg-MA) hydrogel controls, or oxidized Alg-MA (Alg-MA-Ox) tissue adhesive tissue sealants, which form covalent bonds with extracellular matrix (ECM) proteins. Our study investigated the potential for visible-light crosslinked Alg-MA-Ox hydrogels to serve as effective surgical tissue sealants for dynamic in vivo systems. The Alg-MA-Ox hydrogels were designed to be an injectable system, curable in situ. Burst pressure experiments were conducted on a custom-fabricated burst pressure device using constant air flow; burst pressure properties and adhesion characteristics correlated with the degrees of methacrylation and oxidation. In summary, visible light crosslinked Alg-MA-Ox hydrogel tissue sealants form effective seals over critically-sized defects, and maintain pressures up to 50mm Hg. PMID:26897093

  8. 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

  9. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  11. MWCNTs/Cellulose Hydrogels Prepared from NaOH/Urea Aqueous Solution with Improved Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Yingpu Zhang

    2015-01-01

    Full Text Available Novel high strength composite hydrogels were designed and synthesized by introducing multiwalled carbon nanotubes (MWCNTs into cellulose/NaOH/urea aqueous solution and then cross-linked by epichlorohydrin. MWCNTs were used to modify the matrix of cellulose. The structure and morphology of the hydrogels were characterized by Fourier transform infrared (FT-IR spectroscopy, high resolution transmission electron microscopy (HR-TEM, and scanning electron microscopy (SEM. The results from swelling testing revealed that the equilibrium swelling ratio of hydrogels decreased with the increment of MWCNTs content. Thermogravimetric analysis (TGA and dynamic mechanical analysis (DMA results demonstrated that the introduction of MWCNT into cellulose hydrogel networks remarkably improved both thermal and mechanical properties of the composite hydrogels. The preparation of MWCNTs modifiedcellulose-based composites with improved mechanical properties was the first important step towards the development of advanced functional materials.

  12. Engineering interpenetrating network hydrogels as biomimetic cell niche with independently tunable biochemical and mechanical properties.

    Science.gov (United States)

    Tong, Xinming; Yang, Fan

    2014-02-01

    Hydrogels have been widely used as artificial cell niche to mimic extracellular matrix with tunable properties. However, changing biochemical cues in hydrogels developed-to-date would often induce simultaneous changes in mechanical properties, which do not support mechanistic studies on stem cell-niche interactions. Here we report the development of a PEG-based interpenetrating network (IPN), which is composed of two polymer networks that can independently and simultaneously crosslink to form hydrogels in a cell-friendly manner. The resulting IPN hydrogel allows independently tunable biochemical and mechanical properties, as well as stable and more homogeneous presentation of biochemical ligands in 3D than currently available methods. We demonstrate the potential of our IPN platform for elucidating stem cell-niche interactions by modulating osteogenic differentiation of human adipose-derived stem cells. The versatility of such IPN hydrogels is further demonstrated using three distinct and widely used polymers to form the mechanical network while keeping the biochemical network constant.

  13. 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.

  14. 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

  15. 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.

  16. Mechanically strong triple network hydrogels based on hyaluronan and poly(N,N-dimethylacrylamide).

    Science.gov (United States)

    Tavsanli, Burak; Can, Volkan; Okay, Oguz

    2015-11-21

    Hyaluronan (HA) is a natural polyelectrolyte with distinctive biological functions. Cross-linking of HA to generate less degradable hydrogels for use in biomedical applications has attracted interest over many years. One limitation of HA hydrogels is that they are very brittle and/or easily dissolve in physiological environments, which limit their use in load-bearing applications. Herein, we describe the preparation of triple-network (TN) hydrogels based on HA and poly(N,N-dimethylacrylamide) (PDMA) of high mechanical strength by sequential gelation reactions. TN hydrogels containing 81-91% water sustain compressive stresses above 20 MPa and exhibit Young's moduli of up to 1 MPa. HA of various degrees of methacrylation was used as a multifunctional macromer for the synthesis of the brittle first-network component, while loosely cross-linked PDMA was used as the ductile, second and third network components of TN hydrogels. By tuning the methacrylation degree of HA, double-network hydrogels with a fracture stress above 10 MPa and a fracture strain of 96% were obtained. Increasing the ratio of ductile-to-brittle components via the TN approach further increases the fracture stress above 20 MPa. Cyclic mechanical tests show that, although TN hydrogels internally fracture even under small strain, the ductile components hinder macroscopic crack propagation by keeping the macroscopic gel samples together.

  17. 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

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

    Science.gov (United States)

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

    2012-09-01

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

  19. 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.

  20. 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)

  1. 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)

  2. 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

  3. Near-Infrared Light-Responsive Poly(N-isopropylacrylamide)/Graphene Oxide Nanocomposite Hydrogels with Ultrahigh Tensibility.

    Science.gov (United States)

    Shi, Kun; Liu, Zhuang; Wei, Yun-Yan; Wang, Wei; Ju, Xiao-Jie; Xie, Rui; Chu, Liang-Yin

    2015-12-16

    Novel near-infrared (NIR) light-responsive poly(N-isopropylacrylamide)/graphene oxide (PNIPAM-GO) nanocomposite hydrogels with ultrahigh tensibility are prepared by incorporating sparse chemical cross-linking of small molecules with physical cross-linking of graphene oxide (GO) nanosheets. Combination of the GO nanosheets and thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) polymeric networks provides the hydrogels with an excellent NIR light-responsive property. The ultrahigh tensibility of PNIPAM-GO nanocomposite hydrogels is achieved by simply using a very low concentration of N,N'-methylenebis(acrylamide) (BIS) molecules as chemical cross-linkers to generate a relatively homogeneous structure with flexible long polymer chains and rare chemically cross-linked dense clusters. Moreover, the oxidized groups of GO nanosheets enable the formation of a hydrogen bond interaction with the amide groups of PNIPAM chains, which could physically cross-link the PNIPAM chains to increase the toughness of the hydrogel networks. The prepared PNIPAM-GO nanocomposite hydrogels with ultrahigh tensibility exhibit rapid, reversible, and repeatable NIR light-responsive properties, which are highly promising for fabricating remote light-controlled devices, smart actuators, artificial muscles, and so on.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Uncharged Helical Modular Polypeptide Hydrogels for Cellular Scaffolds.

    Science.gov (United States)

    Ahrens, Caroline C; Welch, M Elizabeth; Griffith, Linda G; Hammond, Paula T

    2015-12-14

    Grafted synthetic polypeptides hold appeal for extending the range of biophysical properties achievable in synthetic extracellular matrix (ECM) hydrogels. Here, N-carboxyanhydride polypeptide, poly(γ-propargyl-l-glutamate) (PPLG) macromers were generated by fully grafting the "clickable" side chains with mixtures of short polyethylene glycol (PEG) chains terminated with inert (-OH) or reactive (maleimide and/or norbornene) groups, then reacting a fraction of these groups with an RGD cell attachment motif. A panel of synthetic hydrogels was then created by cross-linking the PPLG macromers with a 4-arm PEG star molecule. Compared to well-established PEG-only hydrogels, gels containing PPLG exhibited dramatically less dependence on swelling as a function of cross-link density. Further, PPLG-containing gels, which retain an α-helical chain conformation, were more effective than standard PEG gels in fostering attachment of a human mesenchymal stem cell (hMSC) line for a given concentration of RGD in the gel. These favorable properties of PPLG-containing PEG hydrogels suggest they may find broad use in synthetic ECM.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Protein surface patterning using nanoscale PEG hydrogels.

    Science.gov (United States)

    Hong, Ye; Krsko, Peter; Libera, Matthew

    2004-12-01

    We have used focused electron-beam cross-linking to create nanosized hydrogels and thus present a new method with which to bring the attractive biocompatibility associated with macroscopic hydrogels into the submicron length-scale regime. Using amine-terminated poly(ethylene glycol) thin films on silicon substrates, we generate nanohydrogels with lateral dimensions of order 200 nm which can swell by a factor of at least five, depending on the radiative dose. With the focused electron beam, high-density arrays of such nanohydrogels can be flexibly patterned onto silicon surfaces. Significantly, the amine groups remain functional after e-beam exposure, and we show that they can be used to covalently bind proteins and other molecules. We use bovine serum albumin to amplify the number of amine groups, and we further demonstrate that different proteins can be covalently bound to different hydrogel pads on the same substrate to create multifunctional surfaces useful in emerging bio/proteomic and sensor technologies.

  20. 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

  1. Separation of water and oil by poly (acrylic acid)-coated stainless steel mesh prepared by radiation crosslinking

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Young Chang; Shin, Jung Woong; Park, Jong Seok; Lim, Young Mook; Jeun, Joon Pyo; Kang, Phil Hyun [Research Division for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2015-05-15

    The stainless steel mesh coated with poly(acrylic acid) hydrogel was fabricated and applied for the separation of water and oil. The stainless steel mesh was immersed in aqueous poly (acrylic acid) solution, and then irradiated by radiation to introduce poly(acrylic acid) hydrogel on the surface of mesh by crosslinking. It was possible to separate oil and water from mixtures of oil/water effectively using the hydrogel-coated mesh. The effect of irradiation dose, coating thickness, size of mesh on the separation efficiency was examined.

  2. Effect of kappa-carrageenan on the properties of poly(N-vinyl pyrrolidone)/kappa-carrageenan blend hydrogel synthesized by {gamma}-radiation technology

    Energy Technology Data Exchange (ETDEWEB)

    Zhai Maolin E-mail: zkkf@pku.edu.cn; Ha Hongfei; Yoshii, F.; Makuuchi, K

    2000-03-01

    A series of hydrogels in the form of rods were prepared from kappa-carrageenan (KC) and poly (N-vinyl pyrrolidone) (PVP) by gamma radiation with {sup 60}Co {gamma} source at room temperature. The properties of the prepared hydrogels, such as the gel strength, gel fraction and swelling behavior were investigated. Incorporation of KC into the PVP/water system increased obviously the gel strength and equilibrium degree of swelling (EDS) of PVP hydrogel. The experimental analyses showed that the crosslinking reaction of PVP was quicker than the degradation of KC at a low dose (less than 30 kGy), and the degradation of KC was inhibited in the PVP/KC mixture system. So an interpenetrating polymer network (IPN) hydrogel composed of PVP (a chemical crosslinking network) and KC (a physical crosslinking network) was proposed here. The existence of different classes of water in this IPN system was shown by water melting curves using DCS. (author)

  3. Characteristic of hyaluronic acid derivative films cross-linked by polyethylene glycol of low water content

    Institute of Scientific and Technical Information of China (English)

    Chen Jinghua; Chen Jingtao; Xu Zheng; Gu Qisheng

    2008-01-01

    Objective: To test the characteristics of byaluronic acid (HA) derivative cross-linked by polyethylene glycol films of low water content. Methods: The cross-linked HA film with 200 μm thickness was got at atmospheric pressure at 25℃ for 5 d. After dried, cross-linked films of 10 mm×10 mm were weighed and immersed in phosphate buffered saline (PBS pH 7.45) at 37℃ for 24 h. Then the solution fraction and water content were estimated. Meanwhile, cross-linked HA derivative films were immersed in phosphate buffered saline (PBS: pH 7.45) at 37℃ for determined time and then implanted subcutaneously in the back of white rats to test in vitro or in vivo degradation characteristic. Results and Conclusion: HA hydrogel cross-linked by polyethylene glycol with water content is as low as 60% and this kind of HA derivative has a slow degradation rate.

  4. 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...

  5. 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

  6. Gossypol-cross-linked boronic acid-modified hydrogels: a functional matrix for the controlled release of an anticancer drug.

    Science.gov (United States)

    Heleg-Shabtai, Vered; Aizen, Ruth; Orbach, Ron; Aleman-Garcia, Miguel Angel; Willner, Itamar

    2015-02-24

    Anticancer drug gossypol cross-links phenylboronic acid-modified acrylamide copolymer chains to form a hydrogel matrix. The hydrogel is dissociated in an acidic environment (pH 4.5), and its dissociation is enhanced in the presence of lactic acid (an α-hydroxy carboxylic acid) as compared to formic acid. The enhanced dissociation of the hydrogel by lactic acid is attributed to the effective separation of the boronate ester bridging groups through the formation of a stabilized complex between the boronic acid substituent and the lactic acid. Because lactic acid exists in cancer cells in elevated amounts and the cancer cells' environment is acidic, the cross-linked hydrogel represents a stimuli-responsive matrix for the controlled release of gossypol. The functionality is demonstrated and characterized by rheology and other spectroscopic means. PMID:25664656

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Broad-spectrum antimicrobial polycarbonate hydrogels with fast degradability.

    Science.gov (United States)

    Pascual, Ana; Tan, Jeremy P K; Yuen, Alex; Chan, Julian M W; Coady, Daniel J; Mecerreyes, David; Hedrick, James L; Yang, Yi Yan; Sardon, Haritz

    2015-04-13

    In this study, a new family of broad-spectrum antimicrobial polycarbonate hydrogels has been successfully synthesized and characterized. Tertiary amine-containing eight-membered monofunctional and difunctional cyclic carbonates were synthesized, and chemically cross-linked polycarbonate hydrogels were obtained by copolymerizing these monomers with a poly(ethylene glycol)-based bifunctional initiator via organocatalyzed ring-opening polymerization using 1,8-diazabicyclo[5.4.0]undec-7-ene catalyst. The gels were quaternized using methyl iodide to confer antimicrobial properties. Stable hydrogels were obtained only when the bifunctional monomer concentration was equal to or higher than 12 mol %. In vitro antimicrobial studies revealed that all quaternized hydrogels exhibited broad-spectrum antimicrobial activity against Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), Pseudomonas aeruginosa (Gram-negative), and Candida albicans (fungus), while the antimicrobial activity of the nonquaternized hydrogels was negligible. Moreover, the gels showed fast degradation at room temperature (4-6 days), which makes them ideal candidates for wound healing and implantable biomaterials.

  16. Poly(vinyl alcohol)-heparin hydrogels as sensor catheter membranes

    NARCIS (Netherlands)

    Brinkman, E.; Does, van der L.; Bantjes, A.

    1991-01-01

    Poly(vinyl alcohol)-heparin hydrogels with varying water content were synthesized for use as sensor catheter membranes. Films were cast from aqueous mixtures of poly(viny) alcohol) (PVA), a photosensitive cross-linker p-diazonium diphenyl amine polymer (PA), glutaraldehyde (GA) and heparin. After dr

  17. Effect of particle size and charge on the network properties of microsphere-based hydrogels

    NARCIS (Netherlands)

    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 me

  18. 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.

  19. 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

  20. 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

  1. 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...

  2. Gelatin-Methacrylamide Hydrogels as Potential Biomaterials for Fabrication of Tissue-Engineered Cartilage Constructs

    NARCIS (Netherlands)

    Schuurman, Wouter; Levett, Peter A.; Pot, Michiel W.; van Weeren, Paul Rene; Dhert, Wouter J. A.; Hutmacher, Dietmar W.; Melchels, Ferry P. W.; Klein, Travis J.; Malda, Jos

    2013-01-01

    Gelatin-methacrylamide (gelMA) hydrogels are shown to support chondrocyte viability and differentiation and give wide ranging mechanical properties depending on several cross-linking parameters. Polymer concentration, UV exposure time, and thermal gelation prior to UV exposure allow for control over

  3. 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.

  4. In-situ formation of growth-factor-loaded coacervate microparticle-embedded hydrogels for directing encapsulated stem cell fate.

    Science.gov (United States)

    Jeon, Oju; Wolfson, David W; Alsberg, Eben

    2015-04-01

    The spontaneous formation of coacervate microdroplet-laden photo-crosslinked hydrogels derived from the simple mixing of oxidized, methacrylated alginate (OMA) and methacrylated gelatin (GelMA) enables simultaneous creation of drug-laden microdroplets and encapsulation of stem cells in photopolymerized coacervate hydrogels under physiological conditions. This can be utilized as a novel platform for in situ formation of localized, sustained bioactive molecule delivery to encapsulate stem cells for therapeutic applications.

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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 ...

  10. Facile synthesis of chitosan/ZnO bio-nanocomposite hydrogel beads as drug delivery systems.

    Science.gov (United States)

    Yadollahi, Mehdi; Farhoudian, Sana; Barkhordari, Soroush; Gholamali, Iman; Farhadnejad, Hassan; Motasadizadeh, Hamidreza

    2016-01-01

    ZnO 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 ZnO nanoparticles (ZnONPs) in the hydrogels was confirmed by X-ray diffraction and scanning electron microscopy studies. SEM micrographs revealed the formation of ZnONPs with size range of 10-25 nm within the hydrogel matrix. Furthermore, the swelling and drug release properties of the beads were studied. The prepared nanocomposite hydrogels showed a pH sensitive swelling behavior. The ZnO nanocomposite hydrogels have rather higher swelling ratio in different aqueous solutions in comparison with neat hydrogel. In vitro drug release test was carried out to prove the effectiveness of this novel type of nanocomposite beads as a controlled drug delivery system. A prolonged and more controlled drug releases were observed for ZnONPs containing chitosan beads, which increased by the increase in ZnONPs content.

  11. Potential Application of a Visible Light-Induced Photocured Hydrogel Film as a Wound Dressing Material

    Directory of Open Access Journals (Sweden)

    Aazadehsadat Hashemi Doulabi

    2015-01-01

    Full Text Available The objective of this work was to prepare hydrogel films, as semi-interpenetrating polymer networks (semi-IPN, based on polyethylene glycol-co-fumarate (PEGF and chitosan (Ch blends. Hydrogel films were prepared by free radical cross-linking of PEGF, an unsaturated aliphatic polyester, in the presence of N-vinyl pyrrolidone (NVP, camphorquinone (CQ, and N,N-dimethyl-p-toluidine (DMPT as a cross-linking, photoinitiating, and accelerating agent, respectively. The effect of NVP concentration on physicochemical and biological properties of semi-IPN film properties was evaluated. The sol fraction, water vapor transmission rate, and swelling degree of the hydrogel films were also investigated. Antibacterial activity against S. aureus was observed for the photocured blend hydrogels of Ch/PEGF with no toxicity to L929 cells according to the cell viability assays. Blend hydrogel films showing 600 ± 88% of equilibrium swelling degree in water and the lowest sol fraction (3.14 ± 1.22% were obtained at 20 wt% of NVP content whilst preserving their own cytocompatibility and antibacterial activity. Therefore, this formulation was considered as an optimal semi-IPN blend hydrogel film composition with potential application for wound dressing.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. Low- and high-resolution nuclear magnetic resonance (NMR) characterisation of hyaluronan-based native and sulfated hydrogels.

    Science.gov (United States)

    Barbucci, Rolando; Leone, Gemma; Chiumiento, Antonio; Di Cocco, Maria Enrica; D'Orazio, Giovanni; Gianferri, Raffaella; Delfini, Maurizio

    2006-08-14

    Hyaluronan-based hydrogels were synthesised using different crosslinking agents, such as 1,3-diaminopropane (1,3-DAP) and 1,6-diaminohexane (1,6-DAE). The hydrogels were sulfated to provide materials (Hyal-1,3-DAP, Hyal-1,6-DAE, HyalS-1,3-DAP and HyalS-1,6-DAE) that were characterised by both high- and low-resolution nuclear magnetic resonance (NMR) spectroscopy. The (13)C NMR spectra of the materials were analysed to identify, characterise and study the crosslinking degree of the hydrogels. The crosslinking degree was also determined by potentiometric titration and the effectiveness of the two techniques was compared. Measurements of longitudinal relaxation times (spin-lattice) and of NOE enhancement were used to study the mobility of the hydrogels. Low-resolution NMR studies allowed the determination of the water transport properties in the hydrogels. In addition, the swelling degree for the various hydrogels was calculated as a function of the longitudinal and transversal relaxation times of the water molecules. Lastly, the self-diffusion coefficients of the water in interaction with the four polysaccharides were measured by the pulsed field gradient spin echo (PFGSE) sequence.

  19. 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.

  20. 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

  1. 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

  2. An Intriguing Method for Fabricating Arbitrarily Shaped “Matreshka” Hydrogels Using a Self-Healing Template

    Directory of Open Access Journals (Sweden)

    Takeshi Sato

    2016-10-01

    Full Text Available This work describes an intriguing strategy for the creation of arbitrarily shaped hydrogels utilizing a self-healing template (SHT. A SHT was loaded with a photo-crosslinkable monomer, PEG diacrylate (PEGDA, and then ultraviolet light (UV crosslinked after first shaping. The SHT template was removed by simple washing with water, leaving behind the hydrogel in the desired physical shape. A hierarchical 3D structure such as “Matreshka” boxes were successfully prepared by simply repeating the “self-healing” and “photo-irradiation” processes. We have also explored the potential of the SHT system for the manipulation of cells.

  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. A novel in situ-formed hydrogel wound dressing by the photocross-linking of a chitosan derivative.

    Science.gov (United States)

    Lu, Guozhong; Ling, Kai; Zhao, Peng; Xu, Zhenghong; Deng, Cao; Zheng, Hua; Huang, Jin; Chen, Jinghua

    2010-01-01

    In situ photopolymerized hydrogel dressings create minimally invasive methods that offer advantages over the use of preformed dressings such as conformability in any wound bed, convenience of application, and improved patient compliance and comfort. Here, we report an in situ-formed hydrogel membrane through ultraviolet cross-linking of a photocross-linkable azidobenzoic hydroxypropyl chitosan aqueous solution. The hydrogel membrane is stable, flexible, and transparent, with a bulk network structure of smoothness, integrity, and density. Fluid uptake ability, water vapor transmission rate, water retention, and bioadhesion of the thus resulted hydrogel membranes (0.1 mm thick) were determined to range from 97.0-96.3%, 2,934-2,561 g/m(2)/day, 36.69-22.94% (after 6 days), and 4.8-12.3 N/cm(2), respectively. These data indicate that the hydrogel membrane can maintain a long period of moist environment over the wound bed for enhancing reepithelialization. Specifically, these properties of the hydrogel membrane were controllable to some extent, by adjusting the substitution degree of the photoreactive azide groups. The hydrogel membrane also exhibited barrier function, as it was impermeable to bacteria but permeable to oxygen. In vitro experiments using two major skin cell types (dermal fibroblast and epidermal keratinocyte) revealed the hydrogel membrane have neither cytotoxicity nor an effect on cell proliferation. Taken together, the in situ photocross-linked azidobenzoic hydroxypropyl chitosan hydrogel membrane has a great potential in the management of wound healing and skin burn.

  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. 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.

  8. 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

  9. The incorporation of extracellular matrix proteins in protein polymer hydrogels to improve encapsulated beta-cell function.

    Science.gov (United States)

    Beenken-Rothkopf, Liese N; Karfeld-Sulzer, Lindsay S; Davis, Nicolynn E; Forster, Ryan; Barron, Annelise E; Fontaine, Magali J

    2013-01-01

    Biomaterial encapsulation of islets has been proposed to improve the long-term success of islet transplantation by recreating a suitable microenvironment and enhancing cell-matrix interactions that affect cellular function. Protein polymer hydrogels previously showed promise as a biocompatible scaffold by maintaining high cell viability. Here, enzymatically-crosslinked protein polymers were used to investigate the effects of varying scaffold properties and of introducing ECM proteins on the viability and function of encapsulated MIN6 β-cells. Chemical and mechanical properties of the hydrogel were modified by altering the protein concentrations while collagen IV, fibronectin, and laminin were incorporated to reestablish cell-matrix interactions lost during cell isolation. Rheology indicated all hydrogels formed quickly, resulting in robust, elastic hydrogels with Young's moduli similar to soft tissue. All hydrogels tested supported both high MIN6 β-cell viability and function and have the potential to serve as an encapsulation platform for islet cell delivery in vivo.

  10. 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.

  11. 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)

  12. Polysaccharide-Based Hydrogels: The Key Role of Water in Affecting Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Rolando Barbucci

    2012-08-01

    Full Text Available Different hydrogels were prepared starting from natural or semi-synthetic polysaccharides (carboxymethylcellulose, hyaluronic acid and chitosan which were cross-linked by the addition of a cross-linking agent chosen according to the chemical groups present along the polymer chains. The cross-linking reaction allows for the formation of a three-dimensional network made of covalent bonds between the polymer chains, which is stable under physiological conditions. The presence of a substantial amount of water within the polysaccharide matrices makes such systems unique among hydrophilic gels. Water itself is responsible for some of their peculiar characteristics, one of which is their injectability which makes these hydrogels suitable for using as matrices for mini-invasive surgery and localized therapy.

  13. Use of Nanofibers to Strengthen Hydrogels of Silica, Other Oxides, and Aerogels

    Science.gov (United States)

    Meador, Mary Ann B.; Capadona, Lynn A.; Hurwitz, Frances; Vivod, Stephanie L.; Lake, Max

    2010-01-01

    Research has shown that including up to 5 percent w/w carbon nanofibers in a silica backbone of polymer crosslinked aerogels improves its strength, tripling compressive modulus and increasing tensile stress-at-break five-fold with no increase in density or decrease in porosity. In addition, the initial silica hydrogels, which are produced as a first step in manufacturing the aerogels, can be quite fragile and difficult to handle before cross-linking. The addition of the carbon nanofiber also improves the strength of the initial hydrogels before cross-linking, improving the manufacturing process. This can also be extended to other oxide aerogels, such as alumina or aluminosilicates, and other nanofiber types, such as silicon carbide.

  14. 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

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

    Prabhudesai, S. A.; Lawrence, Mathias B.; Mitra, S.; Desa, J. A. E.; Mukhopadhyay, R.

    2015-06-01

    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.

  17. 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)

  18. 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.

  19. Fabrication of Self-Healable and Patternable Polypyrrole/Agarose Hybrid Hydrogels for Smart Bioelectrodes.

    Science.gov (United States)

    Park, Nokyoung; Chae, Seung Chul; Kim, Il Tae; Hur, Jaehyun

    2016-02-01

    We present a new class of electrically conductive, mechanically moldable, and thermally self-healable hybrid hydrogels. The hybrid gels consist of polypyrrole and agarose as the conductive component and self-healable matrix, respectively. By using the appropriate oxidizing agent under conditions of mild temperature, the polymerization of pyrrole occurred along the three-dimensional network of the agarose hydrogel matrix. In contrast to most commercially available hydrogels, the physical crosslinking of agarose gel allows for reversible gelation in the case of our hybrid gel, which could be manipulated by temperature variation, which controls the electrical on/off behavior of the hybrid gel electrode. Exploiting this property, we fabricated a hybrid conductive hydrogel electrode which also self-heals thermally. The novel composite material we report here will be useful for many technological and biological applications, especially in reactive biomimetic functions and devices, artificial muscles, smart membranes, smart full organic batteries, and artificial chemical synapses. PMID:27433594

  20. 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

  1. Multiple Stimuli-Responsive Hydrogels for Metal-Based Drug Therapy

    Directory of Open Access Journals (Sweden)

    Mario Casolaro

    2012-03-01

    Full Text Available A series of homopolymeric and copolymeric hydrogels containing the N-isopropylacrylamide and vinyl monomers with α-amino acid (L-valine and L-phenylalanine residues have been synthesized and their swelling properties were evaluated under different external stimulations. The hydrogels, obtained with different cross-linking agents (EBA and PEG-DA, have shown unique properties such as biocompatibility in addition to the stimuli-responsive characters. These ‘smart’ hydrogels exhibit single or multiple stimuli-responsiveness which could be used in biomedical applications, including controlled drug delivery. This article focuses on recent developments dealing with the delivery of metal-based drug (cisplatin, lithium from the stimuli-responsive hydrogels proposed as platforms for cancer and bipolar disorder therapies.

  2. 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.

  3. Application of carboxymethylcellulose hydrogel based silver nanocomposites on cotton fabrics for antibacterial property.

    Science.gov (United States)

    Bozaci, Ebru; Akar, Emine; Ozdogan, Esen; Demir, Asli; Altinisik, Aylin; Seki, Yoldas

    2015-12-10

    In this study, fumaric acid (FA) crosslinked carboxymethylcellulose (CMC) hydrogel (CMCF) based silver nanocomposites were coated on cotton fabric for antibacterial property for the first time. The performance of the nanocomposite treated cotton fabric was tested for different mixing times of hydrogel solution, padding times and concentrations of silver. The cotton fabrics treated with CMC hydrogel based silver nanocomposites demonstrated 99.9% reduction for both Staphylococcus aureus (Sa) and Klebsiella pneumonia (Kp). After one cycle washing processes of treated cotton fabric, there is no significant variation observed in antibacterial activity. From SEM and AFM analyses, silver particles in nano-size, homogenously distributed, were observed. The treated samples were also evaluated by tensile strength, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) analysis, fluid absorbency properties, and whiteness index. The treatment of cotton fabric with CMCF hydrogel did not affect the whiteness considerably, but increased the absorbency values of cotton.

  4. Super stretchable hydrogel achieved by non-aggregated spherulites with diameters <5 nm

    Science.gov (United States)

    Sun, Guoxing; Li, Zongjin; Liang, Rui; Weng, Lu-Tao; Zhang, Lina

    2016-06-01

    The scope of hydrogel applications can be greatly expanded by the improvement of mechanical properties. However, enhancement of nanocomposite hydrogels (NC gels) has been severely limited because the size of crosslinking nanoparticles is too large, at least in one dimension. Here we report a new strategy to synthesize non-aggregated spherulite nanoparticles, with diameters hydrogel. The stress and stretch ratio at rupture of our NC gel are 430 and 121 KPa with only 40-p.p.m. nanoparticle content. The NC gel containing 200-p.p.m. nanoparticles can revert to 90% of its original size after enduring 100-MPa compressive stress. Our results demonstrate that the suppression of nanoparticle size without aggregation helps to establish a super stretchable and high-toughness hydrogel network at very low inorganic content.

  5. 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

  6. 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

  7. 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.

  8. 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

  9. High-resolution nuclear magnetic resonance spectroscopy studies of polysaccharides crosslinked by sodium trimetaphosphate: a proposal for the reaction mechanism.

    Science.gov (United States)

    Lack, Stéphane; Dulong, Virginie; Picton, Luc; Le Cerf, Didier; Condamine, Eric

    2007-05-21

    An NMR spectroscopy study ((31)P, (1)H, (13)C) of the postulated crosslinking mechanism of sodium trimetaphosphate (STMP) on polysaccharides is reported using methyl alpha-D-glucopyranoside as a model. In a first step, reaction of STMP with Glc-OMe gives grafted sodium tripolyphosphate (STPP(g)). On the one hand, STTP(g) can react with a second alcohol functionality to give a crosslinked monophosphate. On the other hand, a monophosphate (grafted phosphate) could be obtained by alkaline degradation of STPP(g). NMR spectroscopy allows to detect the various species formed and to obtain the crosslinking density of STMP-polysaccharides hydrogels. PMID:17303095

  10. 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.

  11. 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

  12. 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

  13. A genetically modified protein-based hydrogel for 3D culture of AD293 cells.

    Science.gov (United States)

    Du, Xiao; Wang, Jingyu; Diao, Wentao; Wang, Ling; Long, Jiafu; Zhou, Hao

    2014-01-01

    Hydrogels have strong application prospects for drug delivery, tissue engineering and cell therapy because of their excellent biocompatibility and abundant availability as scaffolds for drugs and cells. In this study, we created hybrid hydrogels based on a genetically modified tax interactive protein-1 (TIP1) by introducing two or four cysteine residues in the primary structure of TIP1. The introduced cysteine residues were crosslinked with a four-armed poly (ethylene glycol) having their arm ends capped with maleimide residues (4-armed-PEG-Mal) to form hydrogels. In one form of the genetically modification, we incorporated a peptide sequence 'GRGDSP' to introduce bioactivity to the protein, and the resultant hydrogel could provide an excellent environment for a three dimensional cell culture of AD293 cells. The AD293 cells continued to divide and displayed a polyhedron or spindle-shape during the 3-day culture period. Besides, AD293 cells could be easily separated from the cell-gel constructs for future large-scale culture after being cultured for 3 days and treating hydrogel with trypsinase. This work significantly expands the toolbox of recombinant proteins for hydrogel formation, and we believe that our hydrogel will be of considerable interest to those working in cell therapy and controlled drug delivery. PMID:25233088

  14. A genetically modified protein-based hydrogel for 3D culture of AD293 cells.

    Directory of Open Access Journals (Sweden)

    Xiao Du

    Full Text Available Hydrogels have strong application prospects for drug delivery, tissue engineering and cell therapy because of their excellent biocompatibility and abundant availability as scaffolds for drugs and cells. In this study, we created hybrid hydrogels based on a genetically modified tax interactive protein-1 (TIP1 by introducing two or four cysteine residues in the primary structure of TIP1. The introduced cysteine residues were crosslinked with a four-armed poly (ethylene glycol having their arm ends capped with maleimide residues (4-armed-PEG-Mal to form hydrogels. In one form of the genetically modification, we incorporated a peptide sequence 'GRGDSP' to introduce bioactivity to the protein, and the resultant hydrogel could provide an excellent environment for a three dimensional cell culture of AD293 cells. The AD293 cells continued to divide and displayed a polyhedron or spindle-shape during the 3-day culture period. Besides, AD293 cells could be easily separated from the cell-gel constructs for future large-scale culture after being cultured for 3 days and treating hydrogel with trypsinase. This work significantly expands the toolbox of recombinant proteins for hydrogel formation, and we believe that our hydrogel will be of considerable interest to those working in cell therapy and controlled drug delivery.

  15. 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

  16. Design and Evaluation of the Highly Concentrated Human IgG Formulation Using Cyclodextrin Polypseudorotaxane Hydrogels.

    Science.gov (United States)

    Higashi, Taishi; Tajima, Anna; Ohshita, Naoko; Hirotsu, Tatsunori; Abu Hashim, Irhan Ibrahim; Motoyama, Keiichi; Koyama, Sawako; Iibuchi, Ruriko; Mieda, Shiuhei; Handa, Kenji; Kimoto, Tomoaki; Arima, Hidetoshi

    2015-12-01

    To achieve the potent therapeutic effects of human immunoglobulin G (IgG), highly concentrated formulations are required. However, the stabilization for highly concentrated human IgG is laborious work. In the present study, to investigate the potentials of polypseudorotaxane (PPRX) hydrogels consisting of polyethylene glycol (PEG) and α- or γ-cyclodextrin (α- or γ-CyD) as pharmaceutical materials for highly concentrated human IgG, we designed the PPRX hydrogels including human IgG and evaluated their pharmaceutical properties. The α- and γ-CyDs formed PPRX hydrogels with PEG (M.W. 20,000) even in the presence of highly concentrated human IgG (>100 mg/mL). According to the results of (1)H-NMR, powder X-ray diffraction, and Raman microscopy, the formation of human IgG/CyD PPRX hydrogels was based on physical cross-linking arising from their columnar structures. The release profiles of human IgG from the hydrogels were in accordance with the non-Fickian diffusion model. Importantly, the stabilities of human IgG included into the hydrogels against thermal and shaking stresses were markedly improved. These findings suggest that PEG/CyD PPRX hydrogels are useful to prepare the formulation for highly concentrated human IgG.

  17. Radically new cellulose nanocomposite hydrogels: Temperature and pH responsive characters.

    Science.gov (United States)

    Hebeish, A; Farag, S; Sharaf, S; Shaheen, Th I

    2015-11-01

    Innovation produced for synthesis of radically new stimuli-responsive hydrogels were described. The innovation is based on inclusion of cellulose nanowhiskers (CNW)-polyacrylamide (PAAm) copolymer in poly N-isopropyl acrylamide (PNIPAm) semi interpenetrating network (IPN) hydrogel. After being prepared as per free radical polymerization of AAm onto CNW, the as prepared copolymer was incorporated in a polymerization system, which comprises NIPAm monomer, bismethylene acrylamide (BMA) crosslinker, K2S2O8 initiator and TEMED accelerator, to yield CNW-PAAm-PNIPAm nanocomposite hydrogels. The latter address pH-responsive hydrogel as well as temperature-responsive. Hydrogels exhibit the highest equilibrium swelling ratio (ESR) in acidic medium (pH 4). Meanwhile they perform good swelling behavior and hydrophilicity at a temperature of 32°C. These hydrogels carry the characteristic features of CNW-PAAm copolymer as conducted from FTIR and TGA. The hydrogels are homogenous and well-proportioned network structure with highly connected irregular pores with a large size ranging from 30 to 100nm as concluded from SEM.

  18. 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.

  19. Block copolymer mixtures as antimicrobial hydrogels for biofilm eradication.

    Science.gov (United States)

    Lee, Ashlynn L Z; Ng, Victor W L; Wang, Weixin; Hedrick, James L; Yang, Yi Yan

    2013-12-01

    Current antimicrobial strategies have mostly been developed to manage infections due to planktonic cells. However, microbes in their nature state will tend to exist by attaching to and growing on living and inanimate surfaces that result in the formation of biofilms. Conventional therapies for treating biofilm-related infections are likely to be insufficient due to the lower susceptibility of microbes that are embedded in the biofilm matrix. In this study, we report the development of biodegradable hydrogels from vitamin E-functionalized polycarbonates for antimicrobial applications. These hydrogels were formed by incorporating positively-charged polycarbonates containing propyl and benzyl side chains with vitamin E moiety into physically cross-linked networks of "ABA"-type polycarbonate and poly(ethylene glycol) triblock copolymers. Investigations of the mechanical properties of the hydrogels showed that the G' values ranged from 1400 to 1600 Pa and the presence of cationic polycarbonate did not affect the stiffness of the hydrogels. Shear-thinning behavior was observed as the hydrogels displayed high viscosity at low shear rates that dramatically decreased as the shear rate increased. In vitro antimicrobial studies revealed that the more hydrophobic VE/BnCl(1:30)-loaded hydrogels generally exhibited better antimicrobial/antifungal effects compared to the VE/PrBr(1:30) counterpart as lower minimum biocidal concentrations (MBC) were observed in Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative) and Candida albicans (fungus) (156.2, 312.5, 312.5 mg/L for VE/BnCl(1:30) and 312.5, 2500 and 625 mg/L for VE/PrBr(1:30) respectively). Similar trends were observed for the treatment of biofilms where VE/BnCl(1:30)-loaded hydrogels displayed better efficiency with regards to eradication of biomass and reduction of microbe viability of the biofilms. Furthermore, a high degree of synergistic antimicrobial effects was also observed through the co

  20. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    Science.gov (United States)

    Wang, Jingjing; Wei, Jun

    2016-09-01

    Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  1. 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.

  2. 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.

  3. 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.

  4. Development of pH sensitive polyacrylamide grafted pectin hydrogel for controlled drug delivery system.

    Science.gov (United States)

    Sutar, Prashant B; Mishra, Rakesh K; Pal, Kunal; Banthia, Ajit K

    2008-06-01

    In the present study an attempt was made to graft polyacrylamide on pectin. The grafted polymer was characterized by FTIR spectroscopy, differential scanning calorimetry and X-ray diffraction. Rheological property of pectin solution was compared with the product solution. The grafted polymer was cross-linked with varying amount of glutaraldehyde. The swelling properties of the cross-linked product were also studied. The salicylic acid, an antipyretic drug, was incorporated in the cross-linked gel as a model drug and the drug release studies were done in a modified Franz's diffusion cell. The effect of cross-linking density on the release property of salicylic acid was studied through the cross-linked product. The product showed better film forming property and gelling property than pectin. The comparative rheological properties of pectin and grafted copolymer indicated change in the property of the product. FTIR studies indicated incorporation of amide group. Differential scanning calorimetry and XRD suggested formation of a new polymer. Swelling study indicated pH dependent swelling of the cross-linked hydrogel. Salicylic acid release indicated pH dependent release from the hydrogel.

  5. 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.

  6. Visual optical biosensors based on DNA-functionalized polyacrylamide hydrogels.

    Science.gov (United States)

    Khimji, Imran; Kelly, Erin Y; Helwa, Youssef; Hoang, Michael; Liu, Juewen

    2013-12-15

    Biosensors are devices that can provide quantitative or semi-quantitative analytical information about target molecules, where molecular recognition is based on biomolecular interactions. In recent years, DNA has emerged as a useful molecule for biosensor development since DNA can not only recognize its complementary strand, but also metal ions, small molecules, proteins and cells utilizing DNA aptamer technology. Converting DNA binding events into useful biosensors often require sensor immobilization. Among the various materials for sensor immobilization, hydrogels are particularly attractive. Hydrogels are crosslinked hydrophilic polymer networks that undergo swelling in water. In a gel, DNA immobilization can take place in 3D, allowing for high DNA loading capacity. Hydrogels are transparent, offering low optical background. The gel volume is affected by many environmental parameters such as temperature, pH, ionic strength, and solvent composition. In this paper, we present a concise summary of recent developments in DNA-functionalized hydrogel biosensors for visual detection. Detailed methods for immobilizing DNA biosensors in monolithic polyacrylamide gels and gel microparticles are supplied. PMID:23978515

  7. 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.

  8. 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.

  9. Development and characterization of a hydrogel containing nitrofurazone for antimicrobial topical applications.

    Science.gov (United States)

    Vila, Marta M D C; Coelho, Sebastiao L; Chaud, Marco V; Tubino, Matthieu; Oliveira, Jose M; Balcao, Victor M

    2014-01-01

    The goal of the research work entertained herein was the development and characterization of a poly-(vinyl alcohol) (PVA) hydrogel cross-linked with glutaraldehyde and impregnated with 0.2% (w/w) nitrofurazone (NTZ), for topical applications. To verify the active principle release capability, one has determined (i) swelling profile, (ii) in vitro release of NTZ via UV-VIS spectrophotometry, and (iii) antimicrobial activity via exposure to the hydrogel of ATCC strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The optimized hydrogel was further characterized via scanning electron microscopy (SEM), infrared spectroscopy with Fourier transform, moisture content determinations and thermal analyses via thermal gravimetry (TGA). Swelling tests revealed a mass increase from 100±5% up to 350±11%. Incorporated NTZ displayed bactericidal activity, as expected, being released in a linearly controlled fashion above 6 µg/mL during experiment timeframes of 14 h. SEM analyses allowed verification of a homogeneous surface morphology, while infrared spectra showed that NTZ did not bind strongly to the cross-linked polymer. Furthermore, results from thermal analyses suggested a loss of thermal stability arising from incorporation of NTZ in the hydrogel. The optimized hydrogel exhibited characteristics with high potential for (antimicrobial) treatment of skin lesions.

  10. An Injectable Hydrogel as Bone Graft Material with Added Antimicrobial Properties

    Science.gov (United States)

    Tommasi, Giacomo; Perni, Stefano

    2016-01-01

    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

  11. 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

    2016-10-01

    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.

  12. Tough Al-alginate/poly(N-isopropylacrylamide) hydrogel with tunable LCST for soft robotics.

    Science.gov (United States)

    Zheng, Wen Jiang; An, Ning; Yang, Jian Hai; Zhou, Jinxiong; Chen, Yong Mei

    2015-01-28

    Tough Al-alginate/poly(N-isopropylacrylamide) (PNIPAM) hydrogel has been synthesized by introducing an interpenetrating network with hybrid physically cross-linked alginate and chemically cross-linked PNIPAM. Varying the concentration of AlCl3 regulates the mechanical properties of the tough hydrogel and tunes its lower critical solution temperature (LCST) as well. The tough Al-alginate/PNIPAM exhibits 6.3 ± 0.3 MPa of compressive stress and 9.95 of uniaxial stretch. Tunability of LCST is also achieved in a wide range within 22.5-32 °C. A bending beam actuator and a four-arm gripper made of bilayer (Na-alginate/PNIPAM)/(Al-alginate/PNIPAM) hydrogel as prototype of all-hydrogel soft robotics are demonstrated. A finite element (FE) simulation model is developed to simulate the deformation of the soft robotics. The FE simulation not only reproduces the deformation process of performed experiments but also predicts more complicated devices that can be explored in the future. This work broadens the application of temperature-responsive PNIPAM-based hydrogels.

  13. Mechanically robust, rapidly actuating, and biologically functionalized macroporous poly(N-isopropylacrylamide)/silk hybrid hydrogels.

    Science.gov (United States)

    Gil, Eun Seok; Park, Sang-Hyug; Tien, Lee W; Trimmer, Barry; Hudson, Samuel M; Kaplan, David L

    2010-10-01

    A route toward mechanically robust, rapidly actuating, and biologically functionalized polymeric actuators using macroporous soft materials is described. The materials were prepared by combining silk protein and a synthetic polymer (poly(N-isopropylacrylamide) (PNIAPPm)) to form interpenetrating network materials and macroporous structures by freeze-drying, with hundreds of micrometer diameter pores and exploiting the features of both polymers related to dynamic materials and structures. The chemically cross-linked PNIPAAm networks provided stimuli-responsive features, while the silk interpenetrating network formed by inducing protein β-sheet crystallinity in situ for physical cross-links provided material robustness, improved expansion force, and enzymatic degradability. The macroporous hybrid hydrogels showed enhanced thermal-responsive properties in comparison to pure PNIPAAm hydrogels, nonporous silk/PNIPAAm hybrid hydrogels, and previously reported macroporous PNIPAAm hydrogels. These new systems reach near equilibrium sizes in shrunken/swollen states in less than 1 min, with the structural features providing improved actuation rates and stable oscillatory properties due to the macroporous transport and the mechanically robust silk network. Confocal images of the hydrated hydrogels around the lower critical solution temperature (LCST) revealed macropores that could be used to track changes in the real time morphology upon thermal stimulus. The material system transformed from a macroporous to a nonporous structure upon enzymatic degradation. To extend the utility of the system, an affinity platform for a switchable or tunable system was developed by immobilizing biotin and avidin on the macropore surfaces.

  14. 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.

  15. Determination of modification degree in BDDE-modified hyaluronic acid hydrogel by SEC/MS.

    Science.gov (United States)

    Yang, Biao; Guo, Xueping; Zang, Hengchang; Liu, Jianjian

    2015-10-20

    Determination of modification degree in BDDE-modified hyaluronic acid (HA) hydrogel is of particular interest. In this paper, three crosslinking parameters (degree of total modification, t-MOD; degree of cross-link modification, c-MOD; degree of pendent modification, p-MOD) are defined and determined by quantification of the modified fragments in hydrogel digestion by size exclusion chromatography combined with mass spectrometry (SEC-MS). The digestion products of a novel hyaluronidase HAase-B produced by Bacillus sp. A50 are studied and only a few modified fragments are identified by (1)H NMR and MS. As a result, Three HA hydrogels prepared in lab have different t-MOD, c-MOD and p-MOD, but the ratio of c-MOD to p-MOD result in the almost same value of 75%. Hydrogel products from Q-Med have nearly same t-MOD about 0.8% and c-MOD about 0.1%, the ratio of c-MOD to p-MOD is about 13%. Hydrogels from ANTEIS S.A all have much higher t-MOD values, the ratio of c-MOD and p-MOD is about 8%.

  16. 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

  17. 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

  18. 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.

  19. An assessment of the ability of the obstruction-scaling model to estimate solute diffusion coefficients in hydrogels.

    Science.gov (United States)

    Hadjiev, Nicholas A; Amsden, Brian G

    2015-02-10

    The ability to estimate the diffusion coefficient of a solute within hydrogels has important application in the design and analysis of hydrogels used in drug delivery, tissue engineering, and regenerative medicine. A number of mathematical models have been derived for this purpose; however, they often rely on fitted parameters and so have limited predictive capability. Herein we assess the ability of the obstruction-scaling model to provide reasonable estimates of solute diffusion coefficients within hydrogels, as well as the assumption that a hydrogel can be represented as an entangled polymer solution of an equivalent concentration. Fluorescein isothiocyanate dextran solutes were loaded into sodium alginate solutions as well as hydrogels of different polymer volume fractions formed from photoinitiated cross-linking of methacrylate sodium alginate. The tracer diffusion coefficients of these solutes were measured using fluorescence recovery after photobleaching (FRAP). The measured diffusion coefficients were then compared to the values predicted by the obstruction-scaling model. The model predictions were within ±15% of the measured values, suggesting that the model can provide useful estimates of solute diffusion coefficients within hydrogels and solutions. Moreover, solutes diffusing in both sodium alginate solutions and hydrogels were demonstrated to experience the same degree of solute mobility restriction given the same effective polymer concentration, supporting the assumption that a hydrogel can be represented as an entangled polymer solution of equivalent concentration. PMID:25499554

  20. 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.

  1. 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

  2. Enzymatically-responsive pro-angiogenic peptide-releasing poly(ethylene glycol) hydrogels promote vascularization in vivo.

    Science.gov (United States)

    Van Hove, Amy H; Burke, Kathleen; Antonienko, Erin; Brown, Edward; Benoit, Danielle S W

    2015-11-10

    Therapeutic angiogenesis holds great potential for a myriad of tissue engineering and regenerative medicine approaches. While a number of peptides have been identified with pro-angiogenic behaviors, therapeutic efficacy is limited by poor tissue localization and persistence. Therefore, poly(ethylene glycol) hydrogels providing sustained, enzymatically-responsive peptide release were exploited for peptide delivery. Two pro-angiogenic peptide drugs, SPARC113 and SPARC118, from the Secreted Protein Acidic and Rich in Cysteine, were incorporated into hydrogels as crosslinking peptides flanked by matrix metalloproteinase (MMP) degradable substrates. In vitro testing confirmed peptide drug bioactivity requires sustained delivery. Furthermore, peptides retain bioactivity with residual MMP substrates present after hydrogel release. Incorporation into hydrogels achieved enzymatically-responsive bulk degradation, with peptide release in close agreement with hydrogel mass loss and released peptides retaining bioactivity. Interestingly, SPARC113 and SPARC118-releasing hydrogels had significantly different degradation time constants in vitro (1.16 and 8.77×10(-2) h(-1), respectively), despite identical MMP degradable substrates. However, upon subcutaneous implantation, both SPARC113 and SPARC118 hydrogels exhibited similar degradation constants of ~1.45×10(-2) h(-1), and resulted in significant ~1.65-fold increases in angiogenesis in vivo compared to controls. Thus, these hydrogels represent a promising pro-angiogenic approach for applications such as tissue engineering and ischemic tissue disorders.

  3. In silico modeling of the rheological properties of covalently crosslinked collagen triple helices

    CERN Document Server

    Head, David A; Russell, Stephen J; Wood, David J

    2016-01-01

    Biomimetic hydrogels based on natural polymers are a promising class of biomaterial, mimicking the natural extra-cellular matrix of biological tissues and providing cues for cell attachment, proliferation and differentiation. With a view to providing an upstream method to guide subsequent experimental design, the aim of this study was to introduce a mathematical model that described the rheological properties of a hydrogel system based on covalently crosslinked collagen triple helices. In light of their organization, such gels exhibit limited collagen bundling that cannot be described by existing fibril network models. The model presented here treats collagen triple helices as discrete semi-flexible polymers, permits full access to metrics for network microstructure, and should provide a comprehensive understanding of the parameter space associated with the development of such multi-functional materials. Triple helical hydrogel networks were experimentally obtained via reaction of type I collagen with both ar...

  4. Development of honey hydrogel dressing for enhanced wound healing

    Energy Technology Data Exchange (ETDEWEB)

    Yusof, Norimah [Malaysian Institute for Nuclear Technology Research (MINT), Bangi, 43000 Kajang, Selangor (Malaysia)], E-mail: norimah@nuclearmalaysia.gov.my; Ainul Hafiza, A.H.; Zohdi, Rozaini M. [Malaysian Institute for Nuclear Technology Research (MINT), Bangi, 43000 Kajang, Selangor (Malaysia); Bakar, Md Zuki A. [Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang, Selangor (Malaysia)

    2007-11-15

    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.

  5. Cell compatible encapsulation of filaments into 3D hydrogels.

    Science.gov (United States)

    Schirmer, Katharina S U; Gorkin, Robert; Beirne, Stephen; Stewart, Elise; Thompson, Brianna C; Quigley, Anita F; Kapsa, Robert M I; Wallace, Gordon G

    2016-06-01

    Tissue engineering scaffolds for nerve regeneration, or artificial nerve conduits, are particularly challenging due to the high level of complexity the structure of the nerve presents. The list of requirements for artificial nerve conduits is long and includes the ability to physically guide nerve growth using physical and chemical cues as well as electrical stimulation. Combining these characteristics into a conduit, while maintaining biocompatibility and biodegradability, has not been satisfactorily achieved by currently employed fabrication techniques. Here we present a method combining pultrusion and wet-spinning techniques facilitating incorporation of pre-formed filaments into ionically crosslinkable hydrogels. This new biofabrication technique allows the incorporation of conducting or drug-laden filaments, controlled guidance channels and living cells into hydrogels, creating new improved conduit designs. PMID:27213861

  6. 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.

  7. 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

  8. Adhesion in hydrogel contacts

    Science.gov (United States)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  9. 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 ...

  10. 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

  11. Dual Thermosensitive Hydrogels Assembled from the Conserved C-Terminal Domain of Spider Dragline Silk.

    Science.gov (United States)

    Qian, Zhi-Gang; Zhou, Ming-Liang; Song, Wen-Wen; Xia, Xiao-Xia

    2015-11-01

    Stimuli-responsive hydrogels have great potentials in biomedical and biotechnological applications. Due to the advantages of precise control over molecular weight and being biodegradable, protein-based hydrogels and their applications have been extensively studied. However, protein hydrogels with dual thermosensitive properties are rarely reported. Here we present the first report of dual thermosensitive hydrogels assembled from the conserved C-terminal domain of spider dragline silk. First, we found that recombinant C-terminal domain of major ampullate spidroin 1 (MaSp1) of the spider Nephila clavipes formed hydrogels when cooled to approximately 2 °C or heated to 65 °C. The conformational changes and self-assembly of the recombinant protein were studied to understand the mechanism of the gelation processes using multiple methods. It was proposed that the gelation in the low-temperature regime was dominated by hydrogen bonding and hydrophobic interaction between folded protein molecules, whereas the gelation in the high-temperature regime was due to cross-linking of the exposed hydrophobic patches resulting from partial unfolding of the protein upon heating. More interestingly, genetic fusion of the C-terminal domain to a short repetitive region of N. clavipes MaSp1 resulted in a chimeric protein that formed a hydrogel with significantly improved mechanical properties at low temperatures between 2 and 10 °C. Furthermore, the formation of similar hydrogels was observed for the recombinant C-terminal domains of dragline silk of different spider species, thus demonstrating the conserved ability to form dual thermosensitive hydrogels. These findings may be useful in the design and construction of novel protein hydrogels with tunable multiple thermosensitivity for applications in the future.

  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. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. Studying the Effects of Matrix Stiffness on Cellular Function using Acrylamide-based Hydrogels

    Science.gov (United States)

    Cretu, Alexandra; Castagnino, Paola; Assoian, Richard

    2010-01-01

    Tissue stiffness is an important determinant of cellular function, and changes in tissue stiffness are commonly associated with fibrosis, cancer and cardiovascular disease1-11. Traditional cell biological approaches to studying cellular function involve culturing cells on a rigid substratum (plastic dishes or glass coverslips) which cannot account for the effect of an elastic ECM or the variations in ECM stiffness between tissues. To model in vivo tissue compliance conditions in vitro, we and others use ECM-coated hydrogels. In our laboratory, the hydrogels are based on polyacrylamide which can mimic the range of tissue compliances seen biologically12. "Reactive" cover slips are generated by incubation with NaOH followed by addition of 3-APTMS. Glutaraldehyde is used to cross-link the 3-APTMS and the polyacrylamide gel. A solution of acrylamide (AC), bis-acrylamide (Bis-AC) and ammonium persulfate is used for the polymerization of the hydrogel. N-hydroxysuccinimide (NHS) is incorporated into the AC solution to crosslink ECM protein to the hydrogel. Following polymerization of the hydrogel, the gel surface is coated with an ECM protein of choice such as fibronectin, vitronectin, collagen, etc. The stiffness of a hydrogel can be determined by rheology or atomic force microscopy (AFM) and adjusted by varying the percentage of AC and/or bis-AC in the solution12. In this manner, substratum stiffness can be matched to the stiffness of biological tissues which can also be quantified using rheology or AFM. Cells can then be seeded on these hydrogels and cultured based upon the experimental conditions required. Imaging of the cells and their recovery for molecular analysis is straightforward. For this article, we define soft substrata as those having elastic moduli (E) 20,000 Pascal. PMID:20736914

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. Development of Electrically Conductive Double-Network Hydrogels via One-Step Facile Strategy for Cardiac Tissue Engineering.

    Science.gov (United States)

    Yang, Boguang; Yao, Fanglian; Hao, Tong; Fang, Wancai; Ye, Lei; Zhang, Yabin; Wang, Yan; Li, Junjie; Wang, Changyong

    2016-02-18

    Cardiac tissue engineering is an effective method to treat the myocardial infarction. However, the lack of electrical conductivity of biomaterials limits their applications. In this work, a homogeneous electronically conductive double network (HEDN) hydrogel via one-step facile strategy is developed, consisting of a rigid/hydrophobic/conductive network of chemical crosslinked poly(thiophene-3-acetic acid) (PTAA) and a flexible/hydrophilic/biocompatible network of photo-crosslinking methacrylated aminated gelatin (MAAG). Results suggest that the swelling, mechanical, and conductive properties of HEDN hydrogel can be modulated via adjusting the ratio of PTAA network to MAAG network. HEDN hydrogel has Young's moduli ranging from 22.7 to 493.1 kPa, and its conductivity (≈10(-4) S cm(-1)) falls in the range of reported conductivities for native myocardium tissue. To assess their biological activity, the brown adipose-derived stem cells (BADSCs) are seeded on the surface of HEDN hydrogel with or without electrical stimulation. Our data show that the HEDN hydrogel can support the survival and proliferation of BADSCs, and that it can improve the cardiac differentiation efficiency of BADSCs and upregulate the expression of connexin 43. Moreover, electrical stimulation can further improve this effect. Overall, it is concluded that the HEDN hydrogel may represent an ideal scaffold for cardiac tissue engineering.

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Alginate-polyester comacromer based hydrogels as physiochemically and biologically favorable entities for cardiac tissue engineering.

    Science.gov (United States)

    Thankam, Finosh G; Muthu, Jayabalan

    2015-11-01

    The physiochemical and biological responses of tissue engineering hydrogels are crucial in determining their desired performance. A hybrid comacromer was synthesized by copolymerizing alginate and poly(mannitol fumarate-co-sebacate) (pFMSA). Three bimodal hydrogels pFMSA-AA, pFMSA-MA and pFMSA-NMBA were synthesized by crosslinking with Ca(2+) and vinyl monomers acrylic acid (AA), methacrylic acid (MA) and N,N'-methylene bisacrylamide (NMBA), respectively. Though all the hydrogels were cytocompatible and exhibited a normal cell cycle profile, pFMSA-AA exhibited superior physiochemical properties viz non-freezable water content (58.34%) and water absorption per unit mass (0.97 g water/g gel) and pore length (19.92±3.91 μm) in comparing with other two hydrogels. The increased non-freezable water content and water absorption of pFMSA-AA hydrogels greatly influenced its biological performance, which was evident from long-term viability assay and cell cycle proliferation. The physiochemical and biological favorability of pFMSA-AA hydrogels signifies its suitability for cardiac tissue engineering.

  19. Comparative Study of Ultrasonication-Induced and Naturally Self-Assembled Silk Fibroin-Wool Keratin Hydrogel Biomaterials.

    Science.gov (United States)

    Vu, Trang; Xue, Ye; Vuong, Trinh; Erbe, Matthew; Bennet, Christopher; Palazzo, Ben; Popielski, Lucas; Rodriguez, Nelson; Hu, Xiao

    2016-01-01

    This study reports the formation of biocompatible hydrogels using protein polymers from natural silk cocoon fibroins and sheep wool keratins. Silk fibroin protein contains β-sheet secondary structures, allowing for the formation of physical cross-linkers in the hydrogels. Comparative studies were performed on two groups of samples. In the first group, ultrasonication was used to induce a quick gelation of a protein aqueous solution, enhancing the ability of Bombyx mori silk fibroin chains to quickly entrap the wool keratin protein molecules homogenously. In the second group, silk/keratin mixtures were left at room temperature for days, resulting in naturally-assembled gelled solutions. It was found that silk/wool blended solutions can form hydrogels at different mixing ratios, with perfectly interconnected gel structure when the wool content was less than 30 weight percent (wt %) for the first group (ultrasonication), and 10 wt % for the second group (natural gel). Differential scanning calorimetry (DSC) and temperature modulated DSC (TMDSC) were used to confirm that the fibroin/keratin hydrogel system was well-blended without phase separation. Fourier transform infrared spectroscopy (FTIR) was used to investigate the secondary structures of blended protein gels. It was found that intermolecular β-sheet contents significantly increase as the system contains more silk for both groups of samples, resulting in stable crystalline cross-linkers in the blended hydrogel structures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the samples' characteristic morphology on both micro- and nanoscales, which showed that ultrasonic waves can significantly enhance the cross-linker formation and avoid phase separation between silk and keratin molecules in the blended systems. With the ability to form cross-linkages non-chemically, these silk/wool hydrogels may be economically useful for various biomedical applications, thanks to the

  20. Comparative Study of Ultrasonication-Induced and Naturally Self-Assembled Silk Fibroin-Wool Keratin Hydrogel Biomaterials

    Science.gov (United States)

    Vu, Trang; Xue, Ye; Vuong, Trinh; Erbe, Matthew; Bennet, Christopher; Palazzo, Ben; Popielski, Lucas; Rodriguez, Nelson; Hu, Xiao

    2016-01-01

    This study reports the formation of biocompatible hydrogels using protein polymers from natural silk cocoon fibroins and sheep wool keratins. Silk fibroin protein contains β-sheet secondary structures, allowing for the formation of physical cross-linkers in the hydrogels. Comparative studies were performed on two groups of samples. In the first group, ultrasonication was used to induce a quick gelation of a protein aqueous solution, enhancing the ability of Bombyx mori silk fibroin chains to quickly entrap the wool keratin protein molecules homogenously. In the second group, silk/keratin mixtures were left at room temperature for days, resulting in naturally-assembled gelled solutions. It was found that silk/wool blended solutions can form hydrogels at different mixing ratios, with perfectly interconnected gel structure when the wool content was less than 30 weight percent (wt %) for the first group (ultrasonication), and 10 wt % for the second group (natural gel). Differential scanning calorimetry (DSC) and temperature modulated DSC (TMDSC) were used to confirm that the fibroin/keratin hydrogel system was well-blended without phase separation. Fourier transform infrared spectroscopy (FTIR) was used to investigate the secondary structures of blended protein gels. It was found that intermolecular β-sheet contents significantly increase as the system contains more silk for both groups of samples, resulting in stable crystalline cross-linkers in the blended hydrogel structures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the samples’ characteristic morphology on both micro- and nanoscales, which showed that ultrasonic waves can significantly enhance the cross-linker formation and avoid phase separation between silk and keratin molecules in the blended systems. With the ability to form cross-linkages non-chemically, these silk/wool hydrogels may be economically useful for various biomedical applications, thanks to the

  1. Crosslinking biopolymers for biomedical applications.

    Science.gov (United States)

    Reddy, Narendra; Reddy, Roopa; Jiang, Qiuran

    2015-06-01

    Biomaterials made from proteins, polysaccharides, and synthetic biopolymers are preferred but lack the mechanical properties and stability in aqueous environments necessary for medical applications. Crosslinking improves the properties of the biomaterials, but most crosslinkers either cause undesirable changes to the functionality of the biopolymers or result in cytotoxicity. Glutaraldehyde, the most widely used crosslinking agent, is difficult to handle and contradictory views have been presented on the cytotoxicity of glutaraldehyde-crosslinked materials. Recently, poly(carboxylic acids) that can crosslink in both dry and wet conditions have been shown to provide the desired improvements in tensile properties, increase in stability under aqueous conditions, and also promote cell attachment and proliferation. Green chemicals and newer crosslinking approaches are necessary to obtain biopolymeric materials with properties desired for medical applications.

  2. Ex vivo mucoadhesion of different zinc-pectinate hydrogel beads.

    Science.gov (United States)

    Hagesaether, Ellen; Bye, Ragnar; Sande, S Arne

    2008-01-22

    The objective of this study was to investigate the mucoadhesive properties of pre-swelled hydrogel beads made of six types of pectin from three manufacturers. The types of pectin differed mainly in the degree of methoxylation and degree of amidation. Zinc ions were used as cross-linking agent. The mucoadhesive properties were tested on an inverted fresh porcine small intestine attached to a rotating cylinder. Beads made of pectin with a high degree of methoxylation (70%) showed superior mucoadhesive results compared to the other formulations, which could be correlated to the lower amount of zinc in this formulation, subsequently leading to a lower amount of cross-linking and higher mobility of the polymer chains of these beads. This study therefore also indicated the importance of doing mucoadhesive measurements on relevant formulations, and not basing the understanding solely on investigating polymer solutions. Samples from different manufacturers produced the same results.

  3. SWELLING EQUILIBRIUM OF NONIONIC POLYACRYLAMIDE HYDROGEL IN AQUEOUS SALT SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of nonionic polyacrylamide hydrogels, using acrylamide as monomer and N,N’-methylene diacrylamide as crosslinking agent, were prepared by the free radical polymerization in aqueous solution. Swelling equilibria for the gels were carried out in aqueous solutions of NaCl, KCl, CaCl2, Na2HPO4 and K2HPO4 with concentration ranging from 10-3 to 5mol/kgH2O at 25℃. Experimental results revealed that the chlorides and phosphates cause a different behavior at higher salt concentration. The swelling ratio increases with increasing concentration of chlorides salts, while decreases with the increased phosphates salt concentration. The phenomena seem to be related to the different interactions of chloride and hydrogen phosphate ions with the network groups. Furthermore, the effects of different concentration of crosslinking agent and total monomers on gel swelling performance were also investigated.

  4. Synthesis of a novel supermagnetic iron oxide nanocomposite hydrogel based on graft copolymerization of poly((2-dimethylamino)ethyl methacrylate) onto salep for controlled release of drug

    Energy Technology Data Exchange (ETDEWEB)

    Bardajee, Ghasem Rezanejade, E-mail: rezanejad@pnu.ac.ir; Hooshyar, Zari; Asli, Maryam Jahanbakhsh; Shahidi, Fatemeh Emamjome; Dianatnejad, Nastaran

    2014-03-01

    In this research, a novel supermagnetic iron oxide nanocomposite hydrogel was prepared using simultaneous in situ formation of iron oxide nanoparticles (IONs) and three-dimensional cross-linked polymer networks based on graft copolymerization of poly((2-dimethylamino)ethyl methacrylate) (PDMA) onto salep (PDMA-g-salep). The prepared ION–PDMA-g-salep hydrogel was systematically characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDAX), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). In addition, the ION–PDMA-g-salep hydrogel exhibits favorable swelling properties that are sensitive to temperature, pH, and external magnetic field (EMF). The drug release behavior of the prepared hydrogel under EMF, different temperatures and pHs was also studied for the evaluation of the release mechanism and determination of diffusion coefficients. Finally, the antibacterial activity and cytotoxicity studies of the prepared hydrogel were examined. These results suggested that the ION–PDMA-g-salep hydrogel could be a promising candidate for biological dressing applications. - Highlights: • We introduce a novel biocompatible magnetic iron oxide nanocomposite hydrogel for controlled drug release. • We use a facile method to biocompatible magnetic iron oxide nanocomposite hydrogel. • We prepare magnetic iron oxide nanocomposite hydrogel with high pH, temperature, and magnetic field-sensitivity.

  5. 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

  6. 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

  7. 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

  8. 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

  9. Dual-stimuli-responsive hydrogels based on poly(N-isopropylacrylamide)/chitosan semi-interpenetrating networks.

    Science.gov (United States)

    Verestiuc, Liliana; Ivanov, Claudia; Barbu, Eugen; Tsibouklis, John

    2004-01-01

    The synthesis and characterisation of semi-interpenetrating polymeric networks obtained by the radical-induced polymerisation of N-isopropylacrylamide in the presence of chitosan using tetraethyleneglycoldiacrylate as the crosslinker is described. The influence of the degree of crosslinking and that of the ratio of chitosan to poly(N-isopropylacrylamide) on the "pH/temperature induced" phase transition behaviour and swelling characteristics of the hydrogel system are investigated. The ability of the same system to act as a controlled release vehicle for pilocarpine hydrochloride is evaluated. PMID:14698590

  10. 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

  11. Diels-Alder hydrogels with enhanced stability: First step toward controlled release of bevacizumab.

    Science.gov (United States)

    Kirchhof, Susanne; Gregoritza, Manuel; Messmann, Viktoria; Hammer, Nadine; Goepferich, Achim M; Brandl, Ferdinand P

    2015-10-01

    Eight-armed PEG was functionalized with furyl and maleimide groups (8armPEG20k-Fur and 8armPEG20k-Mal); degradable hydrogels were obtained by cross-linking via Diels-Alder chemistry. To increase the stability to degradation, the macromonomers were modified by introducing a hydrophobic 6-aminohexanoic acid spacer between PEG and the reactive end-groups (8armPEG20k-Ahx-Fur and 8armPEG20k-Ahx-Mal). In an alternative approach, the number of reactive groups per macromonomer was increased by branching the terminal ends of eight-armed PEG with lysine (Lys) and Ahx residues (8armPEG20k-Lys-Ahx-Fur2 and 8armPEG20k-Lys-Ahx-Mal2). The hydrolytic resistance of the synthesized macromonomers was determined by UV spectroscopy; the obtained hydrogels were characterized by rheology and degradation studies. The degradation time of 5% (w/v) 8armPEG20k-Ahx hydrogels (28days) was twice as long as the degradation time of 5% (w/v) 8armPEG20k hydrogels (14days); this is explained by increased hydrolytic resistance of the maleimide group. Using dendritic 8armPEG20k-Lys-Ahx macromonomers substantially increased the stability of the resulting hydrogels; degradation of 5% (w/v) 8armPEG20k-Lys-Ahx hydrogels occurred after 34 weeks. 8armPEG20k hydrogels had the largest mesh size of all tested hydrogels, while hydrogels made from dendritic 8armPEG20k-Lys-Ahx macromonomers showed the smallest value. To evaluate their potential for the controlled release of therapeutic antibodies, the hydrogels were loaded with bevacizumab. The incorporated bevacizumab was released over 10 days (8armPEG20k) and 42days (8armPEG20k-Ahx), respectively; release from 8armPEG20k-Lys-Ahx hydrogels was not completed after 105 days. In summary, we believe that 8armPEG20k-Ahx or 8armPEG20k-Lys-Ahx hydrogels could serve as controlled release system for therapeutic antibodies such as bevacizumab.

  12. Is dialdehyde starch a valuable cross-linking agent for collagen/elastin based materials?

    Science.gov (United States)

    Skopinska-Wisniewska, J; Wegrzynowska-Drzymalska, K; Bajek, A; Maj, M; Sionkowska, A

    2016-04-01

    Collagen and elastin are the main structural proteins in mammal bodies. They provide mechanical support, strength, and elasticity to various organs and tissues, e.g. skin, tendons, arteries, and bones. They are readily available, biodegradable, biocompatible and they stimulate cell growth. The physicochemical properties of collagen and elastin-based materials can be modified by cross-linking. Glutaraldehyde is one of the most efficient cross-linking agents. However, the unreacted molecules can be released from the material and cause cytotoxic reactions. Thus, the aim of our work was to investigate the influence of a safer, macromolecular cross-linking agent--dialdehyde starch (DAS). The properties of hydrogels based on collagen/elastin mixtures (95/5, 90/10) containing 5 and 10% of DAS and neutralized via dialysis against deionized water were tested. The homogenous, transparent, stiff hydrogels were obtained. The DAS addition causes the formation of intermolecular cross-linking bonds but does not affect the secondary structure of the proteins. As a result, the thermal stability, mechanical strength, and, surprisingly, swelling ability increased. At the same time, the surface properties test and in vitro study show that the materials are attractive for 3T3 cells. Moreover, the materials containing 10% of DAS are more resistant to enzymatic degradation. PMID:26886815

  13. Is dialdehyde starch a valuable cross-linking agent for collagen/elastin based materials?

    Science.gov (United States)

    Skopinska-Wisniewska, J; Wegrzynowska-Drzymalska, K; Bajek, A; Maj, M; Sionkowska, A

    2016-04-01

    Collagen and elastin are the main structural proteins in mammal bodies. They provide mechanical support, strength, and elasticity to various organs and tissues, e.g. skin, tendons, arteries, and bones. They are readily available, biodegradable, biocompatible and they stimulate cell growth. The physicochemical properties of collagen and elastin-based materials can be modified by cross-linking. Glutaraldehyde is one of the most efficient cross-linking agents. However, the unreacted molecules can be released from the material and cause cytotoxic reactions. Thus, the aim of our work was to investigate the influence of a safer, macromolecular cross-linking agent--dialdehyde starch (DAS). The properties of hydrogels based on collagen/elastin mixtures (95/5, 90/10) containing 5 and 10% of DAS and neutralized via dialysis against deionized water were tested. The homogenous, transparent, stiff hydrogels were obtained. The DAS addition causes the formation of intermolecular cross-linking bonds but does not affect the secondary structure of the proteins. As a result, the thermal stability, mechanical strength, and, surprisingly, swelling ability increased. At the same time, the surface properties test and in vitro study show that the materials are attractive for 3T3 cells. Moreover, the materials containing 10% of DAS are more resistant to enzymatic degradation.

  14. 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

  15. 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

  16. Growth of hydrogel nano- and microlayers covalently bounded onto PE surface

    Science.gov (United States)

    Silva, Rafael; Muniz, Edvani C.; Rubira, Adley F.

    2009-04-01

    Surface modifying strategies were developed to immobilize PAA cross-linked layers (hydrogel layers) with different thicknesses by chemical binding to the surface of polyethylene (PE). Polyethylene films were functionalized by two methods, chromic acid oxidation and maleic anhydride grafting. The reaction of the functional groups placed onto the film surface with ethylenediamine promoted the formation of an amine-functionalized surface. The thickness of the hydrogel layer was correlated with the presence and the release of impregnated ethylenediamine during the immobilization of the PAA chains by thermal esterification. Ethylenediamine acts as a cross-linking agent between different PAA chains. Attenuated total reflectance (ATR) FTIR spectroscopy and scanning electron microscopy (SEM) were used to characterize the chemical composition and the morphologies of the modified film surface.

  17. 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

  18. 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.

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

    Science.gov (United States)

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

    2014-11-28

    Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH7.4) and acetate buffer (AB, pH4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%-14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV.

  20. Initial tree establishment on blocky quarry waste ameliorated with hydrogel or slate processing fines.

    Science.gov (United States)

    Rowe, E C; Williamson, J C; Jones, D L; Holliman, P; Healey, J R

    2005-01-01

    Pocket planting reclamation techniques developed in the 1970s for revegetating blocky quarrying waste have met with very limited success, often because the low water-holding capacity of the waste and limited root development within a small volume of planting pocket material result in severe drought mortality. We tested pocket planting approaches for waste tip reclamation at Europe's largest slate quarry, and compared materials for enhancing the continuity of water- and nutrient-holding down into the interior of the waste tip. When small compost-filled pocket planting bags were placed above slate processing fines (SPF) or water absorbent cross-linked polyacrylamide gel ("hydrogel"), tree growth rates increased in comparison with pocket planting bags alone. The SPF significantly improved tree survival especially during severe drought, but survival was not enhanced by the use of hydrogel. The sorption characteristics of hydrogel indicated that its presence may help to reduce nutrient leaching, but that it may have a negative effect on nitrogen availability. A more likely explanation for the poor performance of pure hydrogel is that it did not maintain sufficient available water, because of discontinuities caused by shrinkage and movement of the hydrogel, and/or degradation of water-holding capacity with environmental exposure. However, the root growth observed in the hydrogel treatments suggests that this technique, if adapted to reduce the effects of hydrogel shrinkage by using finer-grade hydrogel, mixing it with other soil-forming material, and reducing its exposure to extremes of temperature or sunlight, might have the potential to improve the growth and survival of trees planted on sites where delivery of heavy materials such as SPF is impractical. Fine mineral processing waste is freely available at active quarries and should be seen as a key resource for reclamation schemes.