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Sample records for pyrrolidone blended hydrogel

  1. 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.

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

    Science.gov (United States)

    Singh, Durgeshwer; Singh, Antaryami; Singh, Rita

    2015-01-01

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

  3. 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)

  4. 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.

  5. 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)

  6. Rheological behaviour of irradiated wound dressing poly(vinyl pyrrolidone) hydrogels

    Science.gov (United States)

    Lugão, Ademar B.; Rogero, Sizue O.; Malmonge, Sônia M.

    2002-03-01

    The use of hydrogels as biomaterials has increased lately. Poly(vinyl pyrrolidone) (PVP) is an example of polymer hydrogels applied for the synthesis of hydrogel to be used in different biomedical applications. This paper describes a study on rheological properties of PVP hydrogels obtained by gamma radiation techniques. PVP hydrogels were obtained by gamma radiation of PVP water solutions with different radiation doses. It was studied the influence of additives such as poly(ethylene glycol) (PEG), poly(ethylene oxide) (PEO) and glycerol on the rheological behaviour of the gel. The rheological behaviour of hydrogel samples was characterized by measuring the shear storage modulus ( G') under dynamic shear loading. Besides this, sterility and cytotoxicity tests were performed. The study on rheological behaviour of hydrogels showed that G' of PVP gels change according to the additive used. Glycerol increases the fluidity of the gel. The influence of PEG depends on the amount and on its molecular mass. The increase on PEG amount and molecular mass cause a decrease of G' and an increase in the crosslinking density of PVP hydrogel network. The use of high molecular weight PEO allows the increase of the elasticity of the PVP gels.

  7. Growth modulation of fibroblasts by chitosan-polyvinyl pyrrolidone hydrogel: Implications for wound management?

    Indian Academy of Sciences (India)

    Makarand Risbud; Anandwardhan Hardikar; Ramesh Bhonde

    2000-03-01

    Wounds in adults and fetuses differ in their healing ability with respect to scar formation. In adults, wounds lacking the epidermis exhibit excess collagen production and scar formation. Fibroblasts synthesize and deposit a collagen rich extracellular matrix. The early migration and proliferation of fibroblasts in the wound area is implicated in wound scarring. We have synthesized a hydrogel from chitosan-polyvinyl pyrrolidone (PVP) and examined its effect on fibroblast growth modulation in vitro. The hydrogel was found to be hydrophilic as seen from its octane contact angle (141·2 ± 0·37°). The hydrogel was non-toxic and biocompatible with fibroblasts and epithelial cells as confirmed by the 3(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay. It showed dual properties by supporting growth of epithelial cells (SiHa) and selectively inhibiting fibroblast (NIH3T3) growth. Growth inhibition of fibroblasts resulted from their inability to attach on to the hydrogel. These findings are supported by image analysis, which revealed a significant difference ( < 0·05) between the number of fibroblasts attached to the hydrogel in tissue culture as compared to tissue culture treated polystyrene (TCPS) controls. However, no significant difference was observed ( > 0·05) in the number of epithelial (SiHa) cells attached on to the hydrogel as compared to the TCPS control. Although in vivo experiments are awaited, these findings point to the possible use of chitosan-PVP hydrogels in wound-management.

  8. Characterization of pH-sensitive Poly (acrylic acid-co-N-vinyl-2-pyrrolidone) Hydrogels Prepared by Gamma Radiation

    Institute of Scientific and Technical Information of China (English)

    YANG Ming-cheng; HE Su-qin; LIU Wen-tao; SONG Hong-yan; ZHU Cheng-shen

    2007-01-01

    The pH-sensitive copolymer hydrogels were prepared with the monomers of acrylic acid and N-vinyl-2-pyrrolidone based on gamma radiation technique. The morphology of the hydrogels was monitored by using scanning electron microscope. The influence of absorbed dose, monomer compasition and concentration on the swelling ratio (SR) of the hydrogels were investigated in detail. The effect of pH and temperature of the swelling medium on the swelling behavior of the hydrogels were also examined. The results show that the SR of the copolymer hydrogels decreases with the monomer concentration and absorbed dose increasing. The copolymer hydrogels show a better pH-sensitive behavior. In alkaline solution, the SR of the hydrogels is much higher than in acid solution.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-05-02

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

  10. Synthesis and properties of a novel pH sensitive poly(N-vinyl-pyrrolidone-co-sulfadiazine hydrogel

    Directory of Open Access Journals (Sweden)

    2007-03-01

    Full Text Available Sulfadiazine monomer (SDM was synthesized by the reaction of sulfadiazine with acryloyl chloride. The SDM was characterized by 1H-NMR and IR spectra. A novel hydrogel with –SO2NH- group was obtained by the radical copolymerization of SDM with N-vinyl-pyrrolidone (NVP. Effects of the reaction temperature, reaction time, the monomer ratio, and the amount of the cross-linker on the pH sensitivity of the hydrogel were investigated. Results indicate that the hydrogel shows strong pH sensitivity in the pH range of 6.5 to 7.2. It also exhibits a good swelling reversibility at buffer solutions of pH 6.5 and 7.2. At last, drugs tests demonstrated the release effect of the hydrogel in pH range of 6.5 to 7.2.

  11. Chemical treatment of membranes of a polymer blend: Mechanism of the reaction of hypochlorite with poly(vinyl pyrrolidone)

    NARCIS (Netherlands)

    Wienk, I.M.; Meuleman, E.E.B.; Borneman, Z.; Boomgaard, van den Th.; Smolders, C.A.

    1995-01-01

    Sodium hypochlorite solutions are used to treat membranes prepared from a polymeric blend containing poly(vinyl pyrrolidone) (PVP) to increase their water permeability. Sodium hypochlorite affects the membrane material in such a way that PVP is selectively removed from the membrane matrix. The mecha

  12. Syntheses of PVA/starch blend hydrogels by irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Maolin [Peking Univ., College of Chemistry, Inst. of Applied Chemistry, Beijing (China); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Hashim, Kamaruddin [Malaysian Institute for Nuclear Technology Research, Bangi (Malaysia)

    2002-03-01

    A series of excellent PVA/starch blend hydrogels were prepared by gamma and electric beam (EB) radiation at room temperature. The influence of dose, the content of starch in blend system on the properties of the prepared hydrogels were investigated. The gel strength was improved obviously after adding starch into PVA hydrogels, but the swelling properties decreased slightly due to low swelling capacity of starch. The effect of component of starch on the properties of PVA/starch blend hydrogels as well as the reaction mechanism between PVA and starch under irradiation were investigated further. Comparing with PVA/starch blend hydrogels, PVA/amylose blend hydrogels had higher gel fraction, mechanical strength, and lower swelling capacity. PVA/amylopectin blend hydrogels were over the left. It indicated that the amylose of starch was a key component that influenced the properties of PVA/starch blend hydrogels. The analyses of FTIR and DSC spectra of the prepared gel samples after extracting sol indicated that there was a grafting reaction between PVA and starch molecules except for the crosslinking of PVA molecules under irradiation, and the amylose of starch was a key reactive component. (author)

  13. Aligned Electrospun Polyvinyl Pyrrolidone/Poly ɛ-Caprolactone Blend Nanofiber Mats for Tissue Engineering

    Science.gov (United States)

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2016-02-01

    Electrospun nanofibrous materials are widely used in medical applications such as tissue engineering scaffolds, wound dressing material and drug delivery carriers. For tissue engineering scaffolds, the structure of the nanofiber is similar to extracellular matrix (ECM) which promotes the cell growth and proliferation. In the present study, the aligned nanofiber mats of polyvinyl pyrrolidone (PVP) blended poly ɛ-caprolactone (PCL) was successfully generated using electrospinning technique. The morphology of PVP/PCL nanofiber mats were characterized by scanning electron microspore (SEM). The chemical and crystalline structure of PVP/PCL nanofiber mats were analyzed using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffactometer (PXRD). The water contact angle of mats was investigated. Cell culture studies using normal human fibroblasts (NHF) were performed to assess cell morphology, cell alignment and cell proliferation. The results indicated that the fiber were in nanometer range. The PVP/PCL was well dispersed in nanofiber mats and was in amorphous form. The water contact angle of PVP/PCL nanofiber mats was lower than PCL nanofiber mats. The PVP/PCL nanofiber mats exhibited good biocompatibility with NHF cells. In summary, the PVP/PCL nanofiber mats had potential to be used in tissue engineering and regenerative medicine.

  14. Agarose and methylcellulose hydrogel blends for nerve regeneration applications

    Science.gov (United States)

    Martin, Benton C.; Minner, Eric J.; Wiseman, Sherri L.; Klank, Rebecca L.; Gilbert, Ryan J.

    2008-06-01

    Trauma sustained to the central nervous system is a debilitating problem for thousands of people worldwide. Neuronal regeneration within the central nervous system is hindered by several factors, making a multi-faceted approach necessary. Two factors contributing to injury are the irregular geometry of injured sites and the absence of tissue to hold potential nerve guides and drug therapies. Biocompatible hydrogels, injectable at room temperature, that rapidly solidify at physiological temperatures (37 °C) are beneficial materials that could hold nerve guidance channels in place and be loaded with therapeutic agents to aid wound healing. Our studies have shown that thermoreversible methylcellulose can be combined with agarose to create hydrogel blends that accommodate these properties. Three separate novel hydrogel blends were created by mixing methylcellulose with one of the three different agaroses. Gelation time tests show that the blends solidify at a faster rate than base methylcellulose at 37 °C. Rheological data showed that the elastic modulus of the hydrogel blends rapidly increases at 37 °C. Culturing experiments reveal that the morphology of dissociated dorsal root ganglion neurons was not altered when the hydrogels were placed onto the cells. The different blends were further assessed using dissolution tests, pore size evaluations using scanning electron microscopy and measuring the force required for injection. This research demonstrates that blends of agarose and methylcellulose solidify much more quickly than plain methylcellulose, while solidifying at physiological temperatures where agarose cannot. These hydrogel blends, which solidify at physiological temperatures naturally, do not require ultraviolet light or synthetic chemical cross linkers to facilitate solidification. Thus, these hydrogel blends have potential use in delivering therapeutics and holding scaffolding in place within the nervous system.

  15. Radiation stability of resveratrol in immobilization on poly vinyl pyrrolidone hydrogel dressing for dermatological use

    Science.gov (United States)

    Momesso, Roberta G. R. A. P.; Moreno, Carolina S.; Rogero, Sizue O.; Rogero, José R.; Spencer, Patrick J.; Lugão, Ademar B.

    2010-03-01

    The polyphenol trans-resveratrol is a natural phytoalexin, which is found in red wine and in a wide variety of plant species. Resveratrol displays a wide array of biological activities, such as modulation of lipid metabolism, anti-inflammatory and antioxidant activities. This active compound immobilized in polyvinylpyrrolidone (PVP) hydrogel could be very interesting for topical administration, as a dressing form for dermatological use. However, PVP hydrogel obtained by radiation-induced crosslinking can cause undesirable hydrolysis reactions in the active compound. The aim of this work was to verify the resveratrol stability after irradiation at 0.5 and 1 kGy in the presence of ethanol, methanol or tert-butyl alcohol. The integrity of these samples was compared to unirradiated resveratrol by HPLC. The PVP hydrogel matrix was characterized by gel fraction, swelling and in vitro biocompatibility test. The results of gel fraction and swelling degree were approximately 90% and 1600%, respectively. The cytotoxicity assay showed absence of toxicity for this formulation after crosslinking and sterilization, indicating that the PVP hydrogel formulation was appropriate for resveratrol immobilization to produce a dressing for dermatological use.

  16. Radiation stability of resveratrol in immobilization on poly vinyl pyrrolidone hydrogel dressing for dermatological use

    Energy Technology Data Exchange (ETDEWEB)

    Momesso, Roberta G.R.A.P., E-mail: robertapassarelli@yahoo.com.b [IPEN/CNEN-SP-Instituto de Pesquisas Energeticas e Nucleares, Avenida Professor Lineu Prestes, 2242, Cidade Universitaria, Sao Paulo, SP, CEP 05508-000 (Brazil); Moreno, Carolina S.; Rogero, Sizue O.; Rogero, Jose R.; Spencer, Patrick J.; Lugao, Ademar B. [IPEN/CNEN-SP-Instituto de Pesquisas Energeticas e Nucleares, Avenida Professor Lineu Prestes, 2242, Cidade Universitaria, Sao Paulo, SP, CEP 05508-000 (Brazil)

    2010-03-15

    The polyphenol trans-resveratrol is a natural phytoalexin, which is found in red wine and in a wide variety of plant species. Resveratrol displays a wide array of biological activities, such as modulation of lipid metabolism, anti-inflammatory and antioxidant activities. This active compound immobilized in polyvinylpyrrolidone (PVP) hydrogel could be very interesting for topical administration, as a dressing form for dermatological use. However, PVP hydrogel obtained by radiation-induced crosslinking can cause undesirable hydrolysis reactions in the active compound. The aim of this work was to verify the resveratrol stability after irradiation at 0.5 and 1 kGy in the presence of ethanol, methanol or tert-butyl alcohol. The integrity of these samples was compared to unirradiated resveratrol by HPLC. The PVP hydrogel matrix was characterized by gel fraction, swelling and in vitro biocompatibility test. The results of gel fraction and swelling degree were approximately 90% and 1600%, respectively. The cytotoxicity assay showed absence of toxicity for this formulation after crosslinking and sterilization, indicating that the PVP hydrogel formulation was appropriate for resveratrol immobilization to produce a dressing for dermatological use.

  17. Preparation of bacterial cellulose based hydrogels and their viscoelastic behavior

    OpenAIRE

    2015-01-01

    Bacterial cellulose (BC) based hydrogels have been prepared in blended with carboxymethylcellulose and polyvinyl pyrrolidone by using heat treatment. The properties of BC-CMC and BC-PVP hydrogels were compared with pure BC, CMC and PVP hydrogels. These hydrogels were investigated by measuring their structural, morphological and viscoelastic properties. Through the morphological images, alignment of the porous flake like structures could be seen clearly within the inter-polymeric network of th...

  18. Poly(vinyl pyrrolidone) (PVP) hydrogels study for ophthalmologic area utilization; Estudo de hidrogeis de poli(vinil pirrolidona) (PVP) para utilizacao na area oftalmologica

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Renata Hage; Rogero, Sizue Ota; Lugao, Ademar Benevolo [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: farmahage@yahoo.com.br; Cruz, Aurea S. [Instituto Adolfo Lutz, Sao Paulo, SP (Brazil)]. E-mail: aurcruz@ial.sp.gov.br; Sacramento, Rogerio S.; Lima Filho, Acacio A. Souza; Schor, Paulo [Universidade Federal de Sao Paulo (UNIFESP)/Escola Paulista de Medicina, Sao Paulo, SP (Brazil)]. E-mail: rogeroftalmo@yahoo.com.br

    2005-07-01

    Poly (vinyl pyrrolidone) (PVP) hydrogels produced by radiation-induced crosslinking were studied to compose drug delivery system to be used in the eye surface and to manufacture ophthalmic plugs. Some formulations with PVP and poly ethylene glycol (PEG) with different molar mass (300 and 600) were prepared utilizing 0.85% sodium chloride aimed to control the swelling capacity. The obtained hydrogels were characterized by gel fraction and swelling assays. The gel fraction and swelling results indicated no difference in the formulation containing or not NaCl. The gel fraction results varied from 62 to 81% and the swelling degree from 130 to 420%. In vitro assay of cytotoxicity by neutral red uptake method was the first biocompatibility test performed. The results showed no evidence of toxicity in the studied hydrogels. (author)

  19. Characterization of blend hydrogels based on plasticized starch/cellulose acetate/carboxymethyl cellulose synthesized by electron beam irradiation

    Science.gov (United States)

    Senna, Magdy M.; Mostafa, Abo El-Khair B.; Mahdy, Sanna R.; El-Naggar, Abdel Wahab M.

    2016-11-01

    Blend hydrogels based on aqueous solutions of plasticized starch and different ratios of cellulose acetate (CA) and carboxymethyl cellulose (CMC) were prepared by electron beam irradiation (EB). The blends before and after EB irradiation were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The physico-chemical properties of blend hydrogels prepared by electron beam irradiation were improved compared to unirradiated blends.

  20. A study of the swelling and model protein release behaviours of radiation-formed poly(N-vinyl 2-pyrrolidone-co-acrylic acid) hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Wang, David [Centre for Advanced Imaging, University of Queensland, Brisbane 4072 (Australia); Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane 4072 (Australia); Hill, David J.T. [School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane 4072 (Australia); Rasoul, Firas [Centre for Advanced Imaging, University of Queensland, Brisbane 4072 (Australia); Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane 4072 (Australia); Whittaker, Andrew K., E-mail: a.whittaker@uq.edu.a [Centre for Advanced Imaging, University of Queensland, Brisbane 4072 (Australia); Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane 4072 (Australia)

    2011-02-15

    Hydrogels were prepared from poly(acrylic acid-co-N-vinyl pyrrolidone), poly(AA-co-VP) and mixtures of poly(AA-co-VP) and poly(ethylene oxide), PEO, by gamma radiolysis of aqueous solutions of the AA and VP monomers containing ethylene glycol dimethacrylate, EGDMA, as crosslinker and PEO. The AA/VP composition range of the poly(AA-co-VP) was X{sub AA} 0.7-0.9. The swelling behaviours of the hydrogels from the dry state were investigated in water (pH 6.5) and 50 mM 4-(2-hydroxyethyl)piperazine-1-ethylsulfonic acid buffer, HEPES buffer, at pH 7.4 and 295 K. The effects of poly(AA-co-VP) composition, crosslinker mole fraction and the presence of PEO on the equilibrium swelling ratio for the gels was examined. The kinetics of the release of a model protein, horseradish peroxidase, HRP, from the hydrogels in water were also studied at 295 K.

  1. A study of the swelling and model protein release behaviours of radiation-formed poly(N-vinyl 2-pyrrolidone-co-acrylic acid) hydrogels

    Science.gov (United States)

    Wang, David; Hill, David J. T.; Rasoul, Firas; Whittaker, Andrew K.

    2011-02-01

    Hydrogels were prepared from poly(acrylic acid-co-N-vinyl pyrrolidone), poly(AA-co-VP) and mixtures of poly(AA-co-VP) and poly(ethylene oxide), PEO, by gamma radiolysis of aqueous solutions of the AA and VP monomers containing ethylene glycol dimethacrylate, EGDMA, as crosslinker and PEO. The AA/VP composition range of the poly(AA-co-VP) was XAA 0.7-0.9. The swelling behaviours of the hydrogels from the dry state were investigated in water (pH 6.5) and 50 mM 4-(2-hydroxyethyl)piperazine-1-ethylsulfonic acid buffer, HEPES buffer, at pH 7.4 and 295 K. The effects of poly(AA-co-VP) composition, crosslinker mole fraction and the presence of PEO on the equilibrium swelling ratio for the gels was examined. The kinetics of the release of a model protein, horseradish peroxidase, HRP, from the hydrogels in water were also studied at 295 K.

  2. Hydrogel blends with adjustable properties as patches for transdermal delivery.

    Science.gov (United States)

    Mazzitelli, Stefania; Pagano, Cinzia; Giusepponi, Danilo; Nastruzzi, Claudio; Perioli, Luana

    2013-09-15

    The effect of different preparation parameters were analyzed with respect to the rheological and pharmaceutical characteristics of hydrogel blend patches, as transdermal delivery formulation. Mixtures of pectin and gelatin were employed for the production of patches, with adjustable properties, following a two-step gelation procedure. The first gelation, a thermal one, is trigged by the presence of gelatin, whereas, the second gelation, an ionic one, is due to the formation of the typical egg box structure of pectin. In particular, the patch structural properties were assessed by oscillation stress sweep measurements which provided information concerning their viscolelastic properties. In addition, different modalities for drug loading were analyzed with respect to drug homogeneous distribution; testosterone was employed as model drug for transdermal administration. Finally, the performances of the produced transdermal patches were studied, in term of reproducibility and reliability, by determination of in vitro drug release profiles.

  3. Fabrication of chitosan/polyacrylonitrile blend and semi-IPN hydrogel with epichlorohydrin

    Energy Technology Data Exchange (ETDEWEB)

    Aijaz, Muhammad Omer; Haider, Sajjad, E-mail: shaider@ksu.edu.sa; Al Mubddel, Fahad S.; Al Masry, Waheed A. [Department of Chemical Engineering, College of Engineering, King Saud University, P.O BOX 800, Riyadh 11421, KSA (Saudi Arabia)

    2015-05-22

    The present study is focused on the preparation of chitosan (CS)/polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). Blend CS/PAN hydrogel films (HFs) were prepared by solution blending and casting technique. CS in the blend was crosslinked with epichlorohydrin (ECH) to prepare sIPN. The developed CS/PAN blend and sIPN hydrogels were characterized with Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), Thermagravimetric analysis (TGA), and Differential Scanning Calorimeter (DSC). The result showed good miscibility between CS and PAN and crosslinking of CS in the blend. The swelling of the different blended and sIPN hydrogels samples were examined at room temperature (T{sub r}). Blend (C80/P20) sample showed highest swelling (∼2400%) and fair degree of stability (∼28% until 96 h), whereas sIPN hydrogel exhibited relatively low degree of swelling (∼244%) and high degree of aqueous (∼85 % until 96 h), and thermal (onset temperature 304°C) stabilities.

  4. Crystal growth of calcium carbonate on the cellulose acetate/pyrrolidon blend films in the presence of L-aspartic acid

    Science.gov (United States)

    Zhang, Xiuzhen; Xie, Anjian; Huang, Fangzhi; Shen, Yuhua

    2014-03-01

    The morphogenesis and growth process of calcium carbonate on the cellulose acetate/polyvinyl pyrrolidone (CA/PVP) blend films in the presence of L-aspartic acid was carefully investigated. The results showed that the concentration of L-aspartic acid, the initial pH value of reaction solution and temperature turned out to be important factors for the control of morphologies and polymorphs of calcium carbonate. Complex morphologies of CaCO3 particles, such as cubes, rose-like spheres, twinborn-spheres, cone-like, bouquet-like, etc. could be obtained under the different experimental conditions. The dynamic process of formation of rose-like sphere crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. This research may provide a promising method to prepare other inorganic materials with complex morphologies.

  5. Characterization of blend hydrogels based on plasticized starch/cellulose acetate/carboxymethyl cellulose synthesized by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Senna, Magdy M., E-mail: magdysenna@hotmail.com [Radiation Chemistry Department, National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo (Egypt); Mostafa, Abo El-Khair B. [Chemistry Department, College for Girls, Ain Shams University, Cairo (Egypt); Mahdy, Sanna R.; El-Naggar, Abdel Wahab M. [Radiation Chemistry Department, National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo (Egypt)

    2016-11-01

    Highlights: • Semi-interpenetrating (IPN) blend hydrogels were synthesized by EB irradiation. • The hydrogels were based on starch/cellulose acetate/carboxymethyl cellulose blends. • The gelation, swelling, thermal and mechanical properties of hydrogels were studied. • The thermal stability was studied by determining kinetic energy by different methods. - Abstract: Blend hydrogels based on aqueous solutions of plasticized starch and different ratios of cellulose acetate (CA) and carboxymethyl cellulose (CMC) were prepared by electron beam irradiation (EB). The blends before and after EB irradiation were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The physico-chemical properties of blend hydrogels prepared by electron beam irradiation were improved compared to unirradiated blends.

  6. 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.

  7. Pressure-sensitive adhesive properties of poly(N-vinyl pyrrolidone)/D,L-lactic acid oligomer/glycerol/water blends for TDDS.

    Science.gov (United States)

    Zhang, Jianhua; Deng, Liandong; Zhao, Hujia; Liu, Mei; Jin, Hongjian; Li, Jingqing; Dong, Anjie

    2010-01-01

    In order to develop a new type of pressure-sensitive adhesive (PSA) for a transdermal drug-delivery system (TDDS), a quaternary blend (PDGW) composed of poly(N-vinyl pyrrolidone) (PVP), D,L-lactic acid oligomer (DLLAO), glycerol and water was prepared, in which glycerol and water were used as plasticizer. The effects of the number-average molecular weight (M(n)) of DLLAO and the contents of DLLAO and plasticizer on the PSA properties were studied. The results suggest that PDGW exhibits excellent PSA properties when M(n) of DLLAO is in the range of about 200-400 and the contents of DLLAO, glycerol and water are in the range of 5-20, 15-25 and 20-35 wt%, respectively. The miscibility between PVP and DLLAO was investigated via DSC, TGA and FT-IR, and all results indicate that PVP has good miscibility with DLLAO due to strong hydrogen-bond interaction. The storage stability of PDGW also was studied and the results show that the PDGW matrix possesses stable properties over time. In addition, in vivo skin irritation of PDGW was investigated using rabbit as model animal, and the results show that the PDGW does not cause irritation to skin after topical application for 120 h. Therefore, the PDGW possesses excellent PSA properties and presents potential application in TDDS.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-01

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

  10. Preparation of bacterial cellulose based hydrogels and their viscoelastic behavior

    Science.gov (United States)

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

    2015-04-01

    Bacterial cellulose (BC) based hydrogels have been prepared in blended with carboxymethylcellulose and polyvinyl pyrrolidone by using heat treatment. The properties of BC-CMC and BC-PVP hydrogels were compared with pure BC, CMC and PVP hydrogels. These hydrogels were investigated by measuring their structural, morphological and viscoelastic properties. Through the morphological images, alignment of the porous flake like structures could be seen clearly within the inter-polymeric network of the hydrogels. Also, the detail structure analysis of the polymers blended during the hydrogel formation confirms their interactions with each other were studied. Further, the viscoelastic behavior of all the hydrogels in terms of elastic and viscous property was studied. It is observed that at 1% strain, including CMC and PVP hydrogels, all the BC based hydrogels exhibited the linear trend throughout. Also the elastic nature of the material remains high compared to viscous nature. Moreover, the changes could be noticed in case of blended polymer based hydrogels. The values of complex viscosity (η*) decreases with increase in angular frequency within the range of ω = 0.1-100 rad.s-1.

  11. Hydrogel characterization of poly(n-vinyl-2-pyrrolidone) for veterinary use; Caracterizacao do hidrogel de poli(n-vinil-2-pirrolidona) para uso veterinario

    Energy Technology Data Exchange (ETDEWEB)

    Rogero, Sizue O.; Lorenzetti, Solange G.; Lopergolo, Lilian C.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    2002-07-01

    Hydrogel is a polymeric material that exhibits the ability to swell in water and retains a significant fraction of water within its structure, but does not dissolve in water. This work was directed to the study of a new veterinary gel for use as wound dressings. The hydrogels were prepared by gamma irradiation of an aqueous polymer solution with different polysaccharides. The resulting changes in the main properties of the membranes, such as gel content, swelling characteristics and cytotoxicity were investigated. (author)

  12. In situ forming antibacterial dextran blend hydrogel for wound dressing: SAA technology vs. spray drying.

    Science.gov (United States)

    De Cicco, Felicetta; Reverchon, Ernesto; Adami, Renata; Auriemma, Giulia; Russo, Paola; Calabrese, Elena C; Porta, Amalia; Aquino, Rita P; Del Gaudio, Pasquale

    2014-01-30

    This study focuses on designing microparticulate carriers based on high-mannuronic alginate and amidated pectin blend loaded with gentamicin sulphate able to move rapidly from dry to soft hydrogel. Supercritical assisted atomization was used to produce microparticles in form of dry powder and characteristics were compared with those obtained by spray-drying. Particles with very high encapsulation efficiency (approximately 100%) and small diameter (less than 2 μm) showed good flowability and high fluid uptake enabling wound site filling and limiting bacterial proliferation. Moisture transmission of the in situ formed hydrogel was about 95 g/m(2)h, ideal to avoid wound dehydration or occlusion phenomena. All formulations presented a burst effect, suitable to prevent infection spreading at the beginning of the therapy, followed by prolonged release (4-10 days) related to drug/polymers ratio. Antimicrobial tests showed stronger effect than pure GS over time (up-to 24 days) and the ability to degrade preformed biofilms, essential to properly treat infected wounds.

  13. 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.

  14. Synthesis and characterization of pectin/PVP hydrogel membranes for drug delivery system.

    Science.gov (United States)

    Mishra, Rakesh K; Datt, Mahesh; Banthia, Ajit K

    2008-01-01

    The purpose of the present study was to develop and design pectin and polyvinyl pyrrolidone (PVP) blended hydrogel membranes (PEVP), with different pectin: PVP ratios (1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1 w/w), which were prepared by using a conventional solution casting technique. An attempt has been made to characterize the hydrogel membranes by various instrumental techniques like, FTIR (Fourier transform infrared) spectroscopy, X-ray diffraction (XRD), Differential scanning calorimetry (DSC), tensile strength test and scanning electron microscopy (SEM). The release patterns of the drug (salicylic acid) from the hydrogel membrane were done in three different release mediums (pH 1.4, pH 7.4 and distilled water) and samples were analyzed spectrophotometrically at 294 nm wavelength on a UV Vis spectrophotometer. MTT assay was done to ensure cytocompatibility of the pectin/PVP hydrogel membranes using B16 melanoma cells. FTIR spectroscopy indicated the presence of secondary amide (I) absorption bands. The XRD study shows decrease in crystallinity of the hydrogel membranes with increase in PVP ratio. DSC study shows an increase in T(g) of pectin after blending with PVP. It was found that tensile strength increases with increasing PVP ratios in the hydrogel membranes. The prepared hydrogel membranes were found to be biocompatible with B16 melanoma cells.

  15. k-型卡拉胶/聚乙烯吡咯烷酮共混水凝胶的辐射制备及性质研究%燬tudies on Radiation Preparation and Characteristics of k-Carrageenan/PVP Blend Hydrogel

    Institute of Scientific and Technical Information of China (English)

    翟茂林; 哈鸿飞; 吉井文男; 幕内惠三

    2001-01-01

    In this work,a series of hydrogels in the form of rod were prepared from κ-carrageenan(KC) and poly(N-vinyl pyrrolidone) (PVP) by gamma radiation with 60Co γ source at room temperature.The properties of the prepared hydrogels,such as the gel strength,gel fraction and swelling behavior were investigated.High molecular weight PVP (k-90) blending with KC could produces excellent hydrogels,but low molecular weight PVP (k-30) dosen't.With increasing KC content in the prepared hydrogel,both the gel strength and the equilibrium degree of swelling were improved.The experimental analyses showed that the crosslinking reaction of PVP(k-90) was quicker than the degradation of KC at low dose(less than 30 kGy),and the degradation of KC was inhibited in PVP/KC mixture system.An interpenetrating polymer network (IPN) hydrogel composed of PVP (a chemically crosslinked network) and KC (a physically crosslinked network) was proposed.In addition,the dose influenced greatly the preparation of the hydrogel.%采用辐射技术制备了κ-型卡拉胶(KC)/聚乙烯基吡咯烷酮(PVP)共混水凝胶,研究了共混凝胶内KC含量、PVP的分子量和辐照剂量等对KC/PVP共混水凝胶性质的影响.实验发现,KC与高分子量的PVP(k-90)共混后在一定剂量范围内辐照可得到高强度、高溶胀行为的KC/PVP共混水凝胶,随着共混凝胶内KC含量的增加,凝胶强度及溶胀性能均显著提高.分析表明,KC与高分子量的PVP共混后,在较低剂量下KC的降解被抑制,从而获得一种由物理交联的KC和化学交联的PVP形成的互穿网络(IPN)凝胶.

  16. Wound healing potential of a polyvinyl alcohol-blended pectin hydrogel containing Hippophae rahmnoides L. extract in a rat model.

    Science.gov (United States)

    Kim, Jin; Lee, Chang-Moon

    2017-06-01

    In this study, we investigated the effect of a polyvinyl alcohol-blended pectin hydrogel (PVA-PT HG) containing the extracts of Hippophae rhamnoides L. (H. rhamnoides L.) leaves on wound healing in a rat model. The total phenolic content in the extract solution was 40.64±2.7 GAE mg/g and that of flavonoids was 13.15±1.8 QE mg/g. Of the total flavonoids in HGs, 61.6 and 50.0% were released at pH 5.5 and 7.4 after 60min. In rat acute wound models, the wound size was reduced significantly and the recovery rate was significantly higher after treatment with HG containing the extracts, compared with treatment with the control and HG only. The wound healing effects of the HG containing the extracts were confirmed by histological evaluation of the wound tissue. Therefore, HG containing extracts from H. rhamnoides L. leaves enhanced wound healing effectively, and so may be developed as a cover to promote wound healing.

  17. 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.

  18. Physically crosslinked poly(vinyl alcohol-hydroxyethyl starch blend hydrogel membranes: Synthesis and characterization for biomedical applications

    Directory of Open Access Journals (Sweden)

    El-Refaie Kenawy

    2014-07-01

    Full Text Available Poly(vinyl alcohol, PVA is a polymer of great importance because of its many appealing characteristics specifically for various pharmaceutical and biomedical applications. Physically crosslinked hydrogel membranes composed of different amounts of hydroxyethyl starch (HES in (PVA and ampicillin were prepared by applying freeze–thawing method. This freezing–thawing cycle was repeated for three consecutive cycles. Physicochemical properties of PVA–HES membrane gel such as gel fraction, swelling, morphology, elongation, tensile strength, and protein adsorption were investigated. Introducing HES into freeze–thawed PVA structure affected crystal size distribution of PVA; and hence physicochemical properties and morphological structure have been affected. Increased HES concentration decreased the gel fraction %, maximum strength and break elongation. Indeed it resulted into a significant incrementing of the swelling ability, amount of protein adsorption, broader pore size, and pore distribution of membrane morphological structure. Furthermore, an increase in HES concentration resulted in better and still lower thermal stability compared to virgin PVA and freeze–thawed PVA. The maximum weight loss of PVA–HES hydrogel membranes ranged between 18% and 60% according to HES content, after two days of degradation in phosphate buffer saline (PBS, which indicates they are biodegradable. Thus, PVA–HES hydrogel membranes containing ampicillin could be a novel approach for biomedical application e.g. wound dressing purposes.

  19. Catalytic Preparation of Pyrrolidones from Renewable Resources

    Energy Technology Data Exchange (ETDEWEB)

    Frye, John G.; Zacher, Alan H.; Werpy, Todd A.; Wang, Yong

    2005-12-01

    Use of renewable resources for production of valuable chemical commodities is becoming a topic of great national interest and importance. This objective fits well with the USDOE’s objective of promoting the industrial bio-refinery concept in which a wide array of valuable chemical, fuel, food, nutraceuticals and animal feed products all result from the integrated processing of grains, oil seeds and other bio-mass materials. The bio-refinery thus serves to enhance the overall utility and profitability of the agriculture industry as well as helping to reduce the dependence on petroleum. Pyrrolidones fit well with the bio-refinery concept since they may be produced in a scheme beginning with the fermentation of a portion of the bio-refinery’s sugar product into succinate. Pyrrolidones are a class of industrially important chemicals with a variety of uses including as polymer intermediates, cleaners, and “green solvents” which can replace hazardous chlorinated compounds. Battelle has developed an efficient process for the thermo – catalytic conversion of succinate into pyrrolidones, especially n-methylpyrrolidone. The process uses both novel Rh based catalysts and novel aqueous process conditions and results in high selectivities and yields of pyrrolidone compounds. The process also includes novel methodology for enhancing yields by recycling and converting non-useful side products of the catalysis into additional pyrrolidone. The process has been demonstrated in both batch and continuous reactors. Additionally, stability of the unique Rh-based catalyst has been demonstrated.

  20. 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%.

  1. Catalytic Preparation of Pyrrolidones from Renewable Resources

    Energy Technology Data Exchange (ETDEWEB)

    Frye, John G.; Zacher, Alan H.; Werpy, Todd A.; Wang, Yong

    2005-06-01

    Abstract Use of renewable resources for production of valuable chemical commodities is becoming a topic of great national interest and importance. This objective fits well with the U.S. DOE’s objective of promoting the industrial bio-refinery concept in which a wide array of valuable chemical, fuel, food, nutraceuticals, and animal feed products all result from the integrated processing of grains, oil seeds, and other bio-mass materials. The bio-refinery thus serves to enhance the overall utility and profitability of the agriculture industry as well as helping to reduce the USA’s dependence on petroleum. Pyrrolidones fit well into the bio-refinery concept since they may be produced in a scheme beginning with the fermentation of a portion of the bio-refinery’s sugar product into succinate. Pyrrolidones are a class of industrially important chemicals with a variety of uses including polymer intermediates, cleaners, and “green solvents” which can replace hazardous chlorinated compounds. Battelle has developed an efficient process for the thermo-catalytic conversion of succinate into pyrrolidones, especially n-methyl-2-pyrrolidone. The process uses both novel Rh based catalysts and novel aqueous process conditions and results in high selectivities and yields of pyrrolidone compounds. The process also includes novel methodology for enhancing yields by recycling and converting non-useful side products of the catalysis into additional pyrrolidone. The process has been demonstrated in both batch and continuous reactors. Additionally, stability of the unique Rh-based catalyst has been demonstrated.

  2. Local structure of Ca(2+) induced hydrogels of alginate-oligoguluronate blends determined by small-angle-X-ray scattering.

    Science.gov (United States)

    Yuguchi, Yoshiaki; Hasegawa, Ami; Padoł, Anna Maria; Draget, Kurt Ingar; Stokke, Bjørn Torger

    2016-11-01

    Short oligoguluronates, oligoG's, are reported to affect the ionotropic gelation of alginates both with respect to altered gelation kinetics and elastic properties of the resulting gels. The local structure of Ca(2+) induced changes in oligoguluronates and blends of oligoguluronates and alginates was determined by small angle X-ray scattering (SAXS). Calcium was introduced in the aqueous polysaccharide solutions by in situ release of Ca(2+) from Ca-EGTA. The scattering profiles of the Ca(2+)-induced structures in the alginate-oligoG blends were accounted for by a two-component broken rod-like model, also with an additional term representing structural inhomogeneity by a Debye-Bueche term. Adding oligoG to the alginate yields an increase in the largest cross-sectional radius in the region of fractional Ca(2+) saturation of α-l-GulA units from 0.5 to 1. The time-lapse characterization during the Ca-induced changes in the alginate-oligoG blends shows that oligoG delays the emergence of the more extensive laterally aggregated junction zones.

  3. Preparation of PVP hydrogel nanoparticles using lecithin vesicles

    Directory of Open Access Journals (Sweden)

    Vânia Blasques Bueno

    2010-01-01

    Full Text Available Hydrogels micro, sub-micro and nanoparticles are of great interest for drug encapsulation and delivery or as embolotherapic agents. In this work it is described the preparation of nano and sub-microparticles of pre-formed, high molecular weight and monomer free poly(N-vinyl-2-pyrrolidone encapsulated inside the core of lecithin vesicles. The hydrogel particles are formed with a very narrow diameter distribution, of about 800 nm, and a moderate swelling ratio, of approximately 10.

  4. 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)

  5. Radiation modified sago-blends and its potential for biodegradable packaging materials

    Energy Technology Data Exchange (ETDEWEB)

    Ghazali, Z.; Idris, S.; Dahlan, K.Z. [Malaysian Institute for Nuclear Technology Research, Bangi, Kajang (Malaysia); Wongsuban, B.; Adzahan, N.M.; Ithnin, L. [Universiti Putra Malaysia, Faculty of Food Science and Biotechnology, Serdang (Malaysia)

    2002-03-01

    This paper describes work at MINT on the characterisation and development of sago blends as alternative biodegradable packaging materials. A study was undertaken to investigate the effect of formulation, mixing temperature and irradiation dosage on expansion of sago starch-polyvinyl alcohol (PVA) and sago-polyvinyl pyrrolidone (PVP) blends based foam. The foams were produced by microwaving irradiated hydrogels prepared by mixing sago starch with aqueous PVA or PVP. In the development of starch-based plastic, the effect of different composition and different irradiation dosage were studied to evaluate films with good tensile properties, elongation, gas permeability and water vapor transmission rate and also the biodegradability of the film using soil burial test. In another development, irradiation i.e. microwave, electron beam and gamma, has been investigated as a means of degrading the starch granules, which leads to an increase in the amount soluble materials leached. Results showed that irradiation caused an increase in leaching, and a concomitant drastic reduction in swelling volumes of starch granules. It is also showed that the strength of starch gels and viscosity decreased as the levels of irradiation was increased. The degraded starches will be incorporated as an ingredient in the fish cracker and characterized its properties. (author)

  6. Characteristic of Starch-Poly(N-Vinyl-Pyrrolidone) for an encapsulation material in floating drug delivery system

    Science.gov (United States)

    Rositaningsih, N.; Budianto, E.

    2017-04-01

    Modified starch has been widely used in many studies in the field of drug delivery for gastrointestinal drug release. In this study, the starch was modified with poly(N-vinyl-pyrrolidone) by interpenetrating polymer network (IPN) method. Characterizations were done to observe its characteristics in floating drug delivery applications. Three modified starch-based hydrogels were synthesized, i.e. crosslinked starch, semi-IPN, and full-IPN hydrogels. Non-modified starch hydrogel was also synthesized for benchmark purpose. All materials were characterized and analysed by Swelling Test, Buoyancy Test, Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). Swelling test showed that the crosslinked-starch hydrogel has the lowest swelling percentage compared to other hydrogels, whereas non-modified hydrogels tend to have similar swelling percentage to Semi-IPN. Morphology and visual analysis results showed that non-modified hydrogels were physically the most fragile, followed by a crosslinked-starch, semi-IPN-starch, and full-IPN-starch hydrogel. Therefore, full-IPN-starch hydrogel had the highest elasticity. From IR spectrum result, it can be seen that a wavenumbers shift was observed for the modified starch compared with the IR spectrum of pure starch powder. TGA and DSC characterizations showed the degradation temperature for non-modified hydrogel was at 250°C. The degradation temperature for both crosslinked and semi-IPN starch were at 275°C. For full-IPN, however, the degradation temperature was at 225°C. On the other hand, the degradation level could be observed from DSC and TGA results as well. Full-IPN appeared to be the slowest, while non-modified hydrogel seem to be the fastest to degrade. CaCO3 was used as the pore forming agent (PFA) in this research for buoyancy characterization. Buoyancy test showed that the full-IPN had the fastest floating lag and longest floating time followed by

  7. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance....

  8. Spinning of hollow fiber ultrafiltration membranes from a polymer blend

    NARCIS (Netherlands)

    Wienk, I.M.; Wienk, I.M.; Olde scholtenhuis, F.H.A.; van den Boomgaard, Anthonie; Smolders, C.A.; Smolders, C.A.

    1995-01-01

    In this study the dry-wet spinning technique is used for the preparation of hollow fiber membranes. In the polymer solution a blend of two polymers, poly(ether sulfone) and poly(vinyl pyrrolidone), is used. The morphology of the membranes obtained is related to rheological characteristics and phase

  9. RADIATION SYNTHESIS AND CHARACTERIZATION OF POLY (AA-CO-NVP)/CLAY HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Hong-yan Song; Wen-tao Liu; Su-qin He; Ming-cheng Yang; Ya Gao; Cheng-shen Zhu; Liu-suo Wu

    2008-01-01

    The pH-sensitive P(AA-co-NVP)Iclay hydrogels were prepared with the monomers of acrylic acid (AA) andN-vinyl-2-pyrrolidone (NVP) based on γ-ray irradiation technique. The influence of pH values of buffer solutions andcontents of clay and NVP on the equilibrium swelling ratio (SR) and compressive properties of the hydrogels wasinvestigated in detail. The results of swelling property tests showed that, with the increase of clay content, the SR ofhydrogels increases in the same buffer solution, and the SR of hydrogels with different contents of HTMAB-clay is higherthan that of P(A.A-co-NVP) hydrogels without clay. When the content of clay is 15%, the SR of P(AA-co-NVP)/clayhydrogel is 201 at pH=9.8, which is 1.23 times of that of the P(AA-co-NVP) hydrogel (164). In addition, the SR ofP(AA-co-NVP)/clay hydrogel is higher than that of PAA/clay hydrogel in the same solution. The compressive properties ofthe hydrogel were also examined. The results showed that the compressive properties of the P(AA-co-NVP)/clay hydrogelswere improved distinctly as compared to those of the conventional hydrogels without clay. When the content of clay is 15%,the compression strength of the P(AA-co-NVP)/clay hydrogel is 23 times of that of the P(AA-co-NVP) hydrogel.

  10. 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

  11. Radiation preparation of drug carriers based polyacrylic acid (PAAc) using poly(vinyl pyrrolidone) (PVP) as a template polymer

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Rehim, H.A. [National Center for Radiation Research and Technology, Poymer, 3-Ahmed El-Zomor, P.O. Box 29, Cairo, Naser City (Egypt)]. E-mail: ha_rehim@hotmail.com; Hegazy, E.A. [National Center for Radiation Research and Technology, Poymer, 3-Ahmed El-Zomor, P.O. Box 29, Cairo, Naser City (Egypt); Khalil, F.H. [National Center for Radiation Research and Technology, Poymer, 3-Ahmed El-Zomor, P.O. Box 29, Cairo, Naser City (Egypt); Hamed, N.A. [National Center for Radiation Research and Technology, Poymer, 3-Ahmed El-Zomor, P.O. Box 29, Cairo, Naser City (Egypt)

    2007-01-15

    The present study deals with the radiation synthesis of stimuli response hydrophilic polymers from polyacrylic acid (PAAc). To maintain the property of PAAc and control the water swellibility for its application as a drug delivery system, radiation polymerization of AAc in the presence of poly(vinyl pyrrolidone) (PVP) as a template polymer was carried out. Characterization of the prepared PAA/PVP inter-polymer complex was investigated by determining gel content, swelling property, hydrogel microstructure and the release rate of caffeine as a model drug. The release rate of caffeine from the PAA/PVP inter-polymer complexes showed pH-dependency, and seemed to be mainly controlled by the dissolution rate of the complex above a pK {sub a} of PAAc. The prepared inter-polymer complex could be used for application as drug carriers.

  12. Synthesis and characterization of semi-interpenetrating networks of chitosan and poly(N-vinyl-2-pyrrolidone

    Directory of Open Access Journals (Sweden)

    Milosavljević Nedeljko B.

    2010-01-01

    Full Text Available A semi-interpenetrating networks (semi-IPNs based on chitosan and poly(N-vinyl-2-pyrrolidone were prepared in order to achieve better mechanical properties. The samples were characterized by FTIR, SEM, DMA analysis and the swelling behavior at different pHs (2.0-8.0. The semi-IPNs composition was found to have a great impact the hydrogel structure, mechanical properties, morphology and swelling kinetics. The gels demonstrated substantial change in buffer absorbency with the change of pH, high for acid buffers and lower for pH values above 6 where the swelling was considerably slow. Incorporation of PVP led to better mechanical strength of semi-IPNs keeping satisfactory degree of swelling which make them suitable for various applications.

  13. Study of polymeric hydrogels with inorganic nanoparticles of clay; Estudo de hidrogeis polimericos com nanoparticulas inorganicas de argila

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-01

    Nanoscience has been applied in research of intelligent systems for drug delivery. The use of biodegradable synthetic polymers and in diagnostics and therapy has stimulated the application of nanotechnology in polymeric systems with new structures and new materials composing among these materials are hydrogels. Hydrogel with dispersed clay is a new class of materials that combine flexible and permeability of the hydrogels with the high efficiency of the clay to adsorb different substances. We evaluated the behaviour of swelling, gel fraction and thermal stability among the hydrogels obtained by poly (vinyl alcohol) (PVAl) with clay and poly (N-2-vinyl-pyrrolidone) (PVP) with clay. While, observed that the hydrogels showed swelling clay PVAl meaningful, the clay PVP hydrogels showed swelling more consistent after four hours of testing.

  14. 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 ...

  15. Synthesis and characterization of porous microspheres bearing pyrrolidone units

    Energy Technology Data Exchange (ETDEWEB)

    Maciejewska, M., E-mail: mmacieje@umcs.pl; Kołodyńska, D.

    2015-01-15

    Porous microspheres of glycydyl methacrylate (GMA) cross-linked with trimethylolpropane trimethacrylate (TRIM) were prepared with toluene as porogen by suspension-emulsion polymerization. With increasing molar ratio of the functional monomer to cross-linker, the epoxy group content increases significantly whereas the parameters of porous structure (specific surface area and total pore volume) decreases. In order to obtain adsorbents bearing functional groups the porous methacrylate network was modified by subsequent reaction with pyrrolidone. The materials were studied using elemental analysis, infrared spectroscopy, atomic force microscopy (AFM), attenuated total reflection (ATR) spectroscopy, Raman spectroscopy, thermal gravimetry. Additionally, polymers sorption capacity towards Cu(II) was investigated. - Highlights: • Porous microspheres with reactive epoxy group were synthesized. • Highly developed porous structure was created. • Pyrrolidone units were incorporated during ring–opening reaction. • Polymers sorption capacity towards Cu (II) was investigated.

  16. Biomonitoring of N-ethyl-2-pyrrolidone in automobile varnishers.

    Science.gov (United States)

    Koslitz, Stephan; Meier, Swetlana; Schindler, Birgit Karin; Weiss, Tobias; Koch, Holger Martin; Brüning, Thomas; Käfferlein, Heiko Udo

    2014-12-01

    N-alkyl-2-pyrrolidones are important organic solvents for varnishes in industry. This study investigates exposure to N-ethyl-2-pyrrolidone (NEP) in varnishing of hard plastic components in an automobile plant. Two specific biomarkers of exposure, 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI), were analyzed in urine samples of 14 workers. For this purpose, pre-shift, post-shift and next day pre-shift urine samples were collected midweek. Twelve workers performed regular work tasks (loading, wiping and packing), whereas two workers performed special work tasks including cleaning the sprayer system with organic solvents containing N-alkyl-2-pyrrolidones. Spot urine samples of nine non-exposed persons of the same plant served as controls. Median post-shift urinary levels of workers with regular work tasks (5-HNEP: 0.15 mg/L; 2-HESI: 0.19 mg/L) were ∼5-fold higher compared to the controls (0.03 mg/L each). Continuously increasing metabolite levels, from pre-shift via post-shift to pre-shift samples of the following day, were observed in particular for the two workers with the special working tasks. Maximum levels were 31.01 mg/L (5-HNEP) and 8.45 mg/L (2-HESI). No clear trend was evident for workers with regular working tasks. In summary, we were able to show that workers can be exposed to NEP during varnishing tasks in the automobile industry.

  17. Analysis of Asphaltenes Subfractionated by N-Methyl-2-pyrrolidone

    DEFF Research Database (Denmark)

    Ascanius, Birgit Elkjær; Garcia, Daniel Merino; Andersen, Simon Ivar

    2004-01-01

    -pyrrolidone (NMP) as a mobile phase. However, an NMP-insoluble asphaltene fraction of 9-53 wt % was observed for different petroleum n-heptane asphaltenes. Further analysis of the insoluble fraction surprisingly has shown that this fraction hardly exhibits any ultraviolet-visible light absorption...... or fluorescence. This result implies that a substantial fraction of asphaltenes will not be represented in a fluorescence spectrum. This finding may have great implications in the capacity of fluorescence spectroscopy to analyze asphaltenes....

  18. Polymeric blend nanocomposite membranes for ethanol dehydration-effect of morphology and membrane-solvent interactions

    Science.gov (United States)

    Nanocomposite membranes (NCMs) of sodium alginate/poly(vinyl pyrrolidone) blend polymers incorporated with varying concentrations of phosphotungstic acid (H3PW12O40) (PWA) nanoparticles have been prepared and used in ethanol dehydration by the pervaporation (PV) technique. Effe...

  19. 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.

  20. Effects of pore forming agents on chitosan-graft-poly(N-vinylpyrrolidone) hydrogel properties for use as a matrix for floating drug delivery

    Science.gov (United States)

    Budianto, E.; Al-Shidqi, M. F.; Cahyana, A. H.

    2017-07-01

    Eradicating H. pylori-based infection by using conventional oral dosage form of amoxicillin trihydrate finds difficulties to overcome rapid gastric retention time. Encapsulating amoxicillin trihydrate in floating drug delivery system may solve the problem. In this research, the floating drug delivery system of amoxicillin trihydrate encapsulated in floating chitosan-graft-poly(N-vinyl pyrrolidone) hydrogels containing CaCO3 and NaHCO3 as pore forming agents has been successfully prepared. Pore forming agents used was varied with the ratio of 10 to 25% pore forming agents to total mass of the used materials. The hydrogel were characterizedusing FTIR spectrophotometer and stereo microscope. As pore forming agents compositions increased, the porosity (%) and floating properties increased but followed by decrease in drug entrapment efficiency. Most of the floating hydrogels possessed floating ability longer than 180 min and the highest porosity was found in hydrogel containing 25% NaHCO3. Hydrogel containing CaCO3 showed sustained drug release profile than hydrogel containing NaHCO3. However, the optimum formulation was achieved at composition of 10% NaHCO3 with 57% of drug entrapped within the hydrogel and 43% drug released. The results of these studies show that NaHCO3 is an effective pore forming agents for chitosan-graft-poly(N-vinyl pyrrolidone) hydrogel preparation as compare to CaCO3.

  1. 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

  2. Bioresponsive hydrogels

    Directory of Open Access Journals (Sweden)

    Rein V. Ulijn

    2007-04-01

    Full Text Available We highlight recent developments in hydrogel materials with biological responsiveness built in. These ‘smart’ biomaterials change properties in response to selective biological recognition events. When exposed to a biological target (nutrient, growth factor, receptor, antibody, enzyme, or whole cell, molecular recognition events trigger changes in molecular interactions that translate into macroscopic responses, such as swelling/collapse or solution-to-gel transitions. The hydrogel transitions may be used directly as optical readouts for biosensing, linked to the release of actives for drug delivery, or instigate biochemical signaling events that control or direct cellular behavior. Accordingly, bioresponsive hydrogels have gained significant interest for application in diagnostics, drug delivery, and tissue regeneration/wound healing.

  3. Smart hydrogel functional materials

    CERN Document Server

    Chu, Liang-Yin; Ju, Xiao-Jie

    2014-01-01

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

  4. Interpenetrating Polymer Network Hydrogels Based on VP/MMA Gel and PLGA Diacrylate Macromers

    Science.gov (United States)

    Lee, J. Hannah; Radzi, Zamri; Swan, Marc; Bucknall, David; Czernuszka, Jan

    2010-03-01

    Hydrogels have been widely used in biomedical applications due to their biocompatibility, similar physical properties to human tissue and appropriate mechanical properties. A thorough understanding of their swelling behavior is necessary to be able to choose the most suitable hydrogel and to applying it optimally. The long term goal of our research is to develop hydrogel systems with controllable swelling behavior for medical/surgical use. For this purpose, interpenetrating polymer network (IPN) hydrogels have been prepared based on the N-vinyl-2-pyrrolidone (VP)/methyl methacrylate (MMA) copolymeric gel and poly(DL-lactic-co-glycolic acid) (PLGA) diacrylate macromers as well as semi-IPN VP/MMA and PLGA hydrogels. The thermal, morphological, mechanical and physical properties of the hydrogels have been characterized and the potential for surgical use verified. This presentation will concentrate on the studies of the swelling kinetics and equilibrium swelling ratios of the hydrogels. In addition, very recent results will be presented on how additions of PLGA can be used to manipulate the swelling behavior of the hydrogel system.

  5. Mechanical properties and in vitro behavior of nanofiber-hydrogel composites for tissue engineering applications.

    Science.gov (United States)

    Kai, Dan; Prabhakaran, Molamma P; Stahl, Benjamin; Eblenkamp, Markus; Wintermantel, Erich; Ramakrishna, Seeram

    2012-03-01

    Hydrogel-based biomaterial systems have great potential for tissue reconstruction by serving as temporary scaffolds and cell delivery vehicles for tissue engineering (TE). Hydrogels have poor mechanical properties and their rapid degradation limits the development and application of hydrogels in TE. In this study, nanofiber reinforced composite hydrogels were fabricated by incorporating electrospun poly(ε-caprolactone) (PCL)/gelatin 'blend' or 'coaxial' nanofibers into gelatin hydrogels. The morphological, mechanical, swelling and biodegradation properties of the nanocomposite hydrogels were evaluated and the results indicated that the moduli and compressive strengths of the nanofiber reinforced hydrogels were remarkably higher than those of pure gelatin hydrogels. By increasing the amount of incorporated nanofibers into the hydrogel, the Young's modulus of the composite hydrogels increased from 3.29 ± 1.02 kPa to 20.30 ± 1.79 kPa, while the strain at break decreased from 66.0 ± 1.1% to 52.0 ± 3.0%. Compared to composite hydrogels with coaxial nanofibers, those with blend nanofibers showed higher compressive strength and strain at break, but with lower modulus and energy dissipation properties. Biocompatibility evaluations of the nanofiber reinforced hydrogels were carried out using bone marrow mesenchymal stem cells (BM-MSCs) by cell proliferation assay and immunostaining analysis. The nanocomposite hydrogel with 25 mg ml(-1) PCL/gelatin 'blend' nanofibers (PGB25) was found to enhance cell proliferation, indicating that the 'nanocomposite hydrogels' might provide the necessary mechanical support and could be promising cell delivery systems for tissue regeneration.

  6. 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)

  7. Blended Learning

    NARCIS (Netherlands)

    Van der Baaren, John

    2009-01-01

    Van der Baaren, J. (2009). Blended Learning. Presentation given at the Mini symposium 'Blended Learning the way to go?'. November, 5, 2009, The Hague, The Netherlands: Netherlands Defence Academy (NDLA).

  8. Blended Learning

    NARCIS (Netherlands)

    Van der Baaren, John

    2009-01-01

    Van der Baaren, J. (2009). Blended Learning. Presentation given at the Mini symposium 'Blended Learning the way to go?'. November, 5, 2009, The Hague, The Netherlands: Netherlands Defence Academy (NDLA).

  9. Conducting polymer-hydrogels for medical electrode applications

    Directory of Open Access Journals (Sweden)

    Rylie A Green, Sungchul Baek, Laura A Poole-Warren and Penny J Martens

    2010-01-01

    Full Text Available Conducting polymers hold significant promise as electrode coatings; however, they are characterized by inherently poor mechanical properties. Blending or producing layered conducting polymers with other polymer forms, such as hydrogels, has been proposed as an approach to improving these properties. There are many challenges to producing hybrid polymers incorporating conducting polymers and hydrogels, including the fabrication of structures based on two such dissimilar materials and evaluation of the properties of the resulting structures. Although both fabrication and evaluation of structure–property relationships remain challenges, materials comprised of conducting polymers and hydrogels are promising for the next generation of bioactive electrode coatings.

  10. Chitosan-containing hydrogel wound dressings prepared by radiation technique

    Science.gov (United States)

    Mozalewska, Wiktoria; Czechowska-Biskup, Renata; Olejnik, Alicja K.; Wach, Radoslaw A.; Ulański, Piotr; Rosiak, Janusz M.

    2017-05-01

    The aim of the study was to develop an antimicrobial hydrogel wound dressing by means of radiation-initiated crosslinking of hydrophilic polymers, i.e. by well-established technology comprising gel manufacturing and its sterilization in one process. The approach included admixture of chitosan of relatively low molecular weight dissolved in lactic acid (LA) into the initial regular components of the conventional hydrogel dressing based on poly(N-vinyl pyrrolidone) (PVP) and agar. Molecular weight of chitosan was regulated by radiation-initiated degradation in the range of 39-132 kg mol-1. Optimum total concentration of LA in the resultant hydrogel dressing was evaluated as 0.05 mol dm-3, that is ca. 0.5%. Presence of LA in the system influenced essential radiation and technological parameters of hydrogel manufacturing. The setting temperature of the pre-hydrogel mixture, resulting from agar ability to congeal, was reduced with LA concentration, yet remained significantly above the room temperature. 0.5% of chitosan was effectively dissolved in aqueous solution of lactic acid due to its pH (lower than 5.5). Radiation parameters of PVP crosslinking in the presence of LA, as determined with generalized Charlesby-Pinner equation, were reflected in slight reduction of the maximum gel fraction and increase in gelation dose and in the factor comparing yields of scission to crosslinking. Nevertheless, essentially physical characteristics of the hydrogel was not affected, except for somewhat increased water uptake capacity, what in turn improves functionality of the dressing as extensive exudate for the wound can be efficiently absorbed. Preliminary microbiological studies showed antimicrobial character of the chitosan-containing hydrogel towards Gram-positive bacterial strain.

  11. Genistein Modified Polymer Blends for Hemodialysis Membranes

    Science.gov (United States)

    Chang, Teng; Kyu, Thein; Define, Linda; Alexander, Thomas

    2012-02-01

    A soybean-derived phytochemical called genistein was used as a modifying agent to polyether sulfone/polyvinyl pyrrolidone (PES/PVP) blends to produce multi-functional hemodialysis membranes. With the aid of phase diagrams of PES/PVP/genistein blends, asymmetric porous membranes were fabricated by coagulating in non-solvent. Both unmodified and genistein modified PES/PVP membranes were shown to be non-cytotoxic to the blood cells. Unmodified PES/PVP membranes were found to reduce reactive oxygen species (ROS) levels, whereas the genistein modified membranes exhibited suppression for ˜60% of the ROS levels. Also, the genistein modified membranes revealed significant suppression of pro-inflammatory cytokines: IL-1β, IL-6, and TNF-α. Moreover, addition of PVP to PES showed the reduced trend of platelet adhesion and then leveled off. However, the modified membranes exhibited suppression of platelet adhesion at low genistein loading, but beyond 15 wt%, the platelet adhesion level rised up.

  12. Laser induced augmentation of silver nanospheres to nanowires in ethanol fostered by Poly Vinyl Pyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Sebastian, Suneetha, E-mail: sunikutty@gmail.com; Linslal, C.L.; Vallabhan, C.P.G.; Nampoori, V.P.N.; Radhakrishnan, P.; Kailasnath, M.

    2014-11-30

    Highlights: • Silver nanospheres are synthesised in ethanol containing Poly Vinyl Pyrrolidone which acts as a polymeric capping agent to nanoparticles thus improving its stability. • Laser irradiation onto the colloidal solution of silver nanoparticles produced well defined nanowires through ripening mechanism promoted by Poly Vinyl Pyrrolidone. • Nanowires so formed are having an average length of 8.7 μm and width of 160 nm. - Abstract: Stable uniform silver nanospheres having an average diameter of 45 nm are synthesised in ethanol containing Poly Vinyl Pyrrolidone using Laser Ablation in Liquid technique. Further irradiation of the nanocolloidal solution by focussed laser beam produced stable well defined silver nanowires through ripening mechanism fostered by the presence of Poly Vinyl Pyrrolidone. Confirmation of the mechanism is obtained from Transmission Electron Microscopic images of the nanocolloidal solution irradiated for different time durations.

  13. Polymer blends

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Scott D.; Naik, Sanjeev

    2017-08-22

    The present invention provides, among other things, extruded blends of aliphatic polycarbonates and polyolefins. In one aspect, provided blends comprise aliphatic polycarbonates such as poly(propylene carbonate) and a lesser amount of a crystalline or semicrystalline polymer. In certain embodiments, provided blends are characterized in that they exhibit unexpected improvements in their elongation properties. In another aspect, the invention provides methods of making such materials and applications of the materials in applications such as the manufacture of consumer packaging materials.

  14. Processing Techniques and Applications of Silk Hydrogels in Bioengineering

    Directory of Open Access Journals (Sweden)

    Michael Floren

    2016-09-01

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

  15. Processing Techniques and Applications of Silk Hydrogels in Bioengineering

    Science.gov (United States)

    Floren, Michael; Migliaresi, Claudio; Motta, Antonella

    2016-01-01

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

  16. Blended learning

    DEFF Research Database (Denmark)

    Staugaard, Hans Jørgen

    2012-01-01

    Forsøg på at indkredse begrebet blended learning i forbindelse med forberedelsen af projekt FlexVid.......Forsøg på at indkredse begrebet blended learning i forbindelse med forberedelsen af projekt FlexVid....

  17. Blended Learning

    Science.gov (United States)

    Imbriale, Ryan

    2013-01-01

    Teachers always have been and always will be the essential element in the classroom. They can create magic inside four walls, but they have never been able to create learning environments outside the classroom like they can today, thanks to blended learning. Blended learning allows students and teachers to break free of the isolation of the…

  18. Blended Learning

    Science.gov (United States)

    Tucker, Catlin; Umphrey, Jan

    2013-01-01

    Catlin Tucker, author of "Blended Learning in Grades 4-12," is an English language arts teacher at Windsor High School in Sonoma County, CA. In this conversation with "Principal Leadership," she defines blended learning as a formal education program in which a student is engaged in active learning in part online where they…

  19. Blended Learning

    Science.gov (United States)

    Imbriale, Ryan

    2013-01-01

    Teachers always have been and always will be the essential element in the classroom. They can create magic inside four walls, but they have never been able to create learning environments outside the classroom like they can today, thanks to blended learning. Blended learning allows students and teachers to break free of the isolation of the…

  20. Blended learning

    DEFF Research Database (Denmark)

    Dau, Susanne

    2016-01-01

    Blended Learning has been implemented, evaluated and researched for the last decades within different educational areas and levels. Blended learning has been coupled with different epistemological understandings and learning theories, but the fundamental character and dimensions of learning...... in blended learning are still insufficient. Moreover, blended learning is a misleading concept described as learning, despite the fact that it fundamentally is an instructional and didactic approach (Oliver & Trigwell, 2005) addressing the learning environment (Inglis, Palipoana, Trenhom & Ward, 2011......) instead of the learning processes behind. Much of the existing research within the field seems to miss this perspective. The consequence is a lack of acknowledgement of the driven forces behind the context and the instructional design limiting the knowledge foundation of learning in blended learning. Thus...

  1. Blended Learning

    DEFF Research Database (Denmark)

    Gynther, Karsten

    2012-01-01

    Artiklen giver en grundlæggende introduktion til begrebet blended learning og sætter fokus på didaktiske spørgsmål som: Hvad er blended learning? Hvilke forskellige former ser vi i dag i danske uddannelser? Hvorfor udbydes uddannelser i stigende grad i et blended learning format? Hvilke didaktiske...... principper kan man som underviser tage i brug, når man skal designe et blended learning forløb? Hvad er den grundlæggende didaktiske forskel på tilstedeværelsesundervisning og netbaseret undervisning? Og hvilke kritiske perspektiver er det vigtigt at have med, når en uddannelsesinstitution beslutter sig...... for at re-designe traditionel tilstedeværelsesundervisning til blended learning?...

  2. Blended learning

    DEFF Research Database (Denmark)

    Dau, Susanne

    2016-01-01

    in blended learning are still insufficient. Moreover, blended learning is a misleading concept described as learning, despite the fact that it fundamentally is an instructional and didactic approach (Oliver & Trigwell, 2005) addressing the learning environment (Inglis, Palipoana, Trenhom & Ward, 2011......Blended Learning has been implemented, evaluated and researched for the last decades within different educational areas and levels. Blended learning has been coupled with different epistemological understandings and learning theories, but the fundamental character and dimensions of learning......) instead of the learning processes behind. Much of the existing research within the field seems to miss this perspective. The consequence is a lack of acknowledgement of the driven forces behind the context and the instructional design limiting the knowledge foundation of learning in blended learning. Thus...

  3. Structuring and calorie control of bakery products by templating batter with ultra melt-resistant food-grade hydrogel beads

    NARCIS (Netherlands)

    Thompson, Benjamin R.; Horozov, Tommy S.; Stoyanov, Simeon D.; Paunov, Vesselin N.

    2017-01-01

    We report the use of a temperature insensitive, food-grade hydrogel to reduce the caloric density of pancakes that were prepared at temperatures much higher than the boiling point of water. This cheap, facile method utilises a mixed agar-methylcellulose hydrogel, which was blended to produce a

  4. Investigation of nanocomposites made with poly(methacrylic acid-co-methyl methacrylate)/poly(N-vinyl-2-pyrrolidone)/multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Guoqin, Liu; Wei, Miao [College of Material Science and Engineering, Henan University of Technology (China); Lin-Jian, Shangguan, E-mail: mikepolymer@126.com [School of Mechanical Engineering, North China University of Water Conservancy and Electric Power (China)

    2014-06-01

    Poly(methacrylic acid-co-methyl methacrylate) (P(MAA-co-MMA)) was prepared in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) and multi-walled carbon nanotubes (MWNTs) via ultrasonic assisted solution free radical polymerization, i.e., P(MAA-co-MMA)/PVP/MWNTs nanocomposites. The morphology, glassy-state storage modulus, thermal behavior and swelling characteristics of P(MAA-co-MMA)/PVP/MWNTs nanocomposites were investigated. Scanning electron micrographs (SEM) revealed that MWNTs at low concentration could be uniformly dispersed into P(MAA-co-MMA)/PVP blends. With increasing MWNTs weight fraction, the average glassy-state modulus, glass transition temperatures and decomposition temperature of the nanocomposites increased, but their swelling characteristics decreased. (author)

  5. Investigation of nanocomposites made with poly(methacrylic acid-co-methyl methacrylate/poly(N-vinyl-2-pyrrolidone/multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Liu Guoqin

    2014-01-01

    Full Text Available Poly(methacrylic acid-co-methyl methacrylate (P(MAA-co-MMA was prepared in the presence of poly(N-vinyl-2-pyrrolidone (PVP and multiwalled carbon nanotubes (MWNTs via ultrasonic assisted solution free radical polymerization, i.e., P(MAA-co-MMA/PVP/MWNTs nanocomposites. The morphology, glassy-state storage modulus, thermal behavior and swelling characteristics of P(MAA-co-MMA/PVP/MWNTs nanocomposites were investigated. Scanning electron micrographs (SEM revealed that MWNTs at low concentration could be uniformly dispersed into P(MAA-co-MMA/PVP blends. With increasing MWNTs weight fraction, the average glassy-state modulus, glass transition temperatures and decomposition temperature of the nanocomposites increased, but their swelling characteristics decreased.

  6. 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.

  7. In-situ photo-assisted deposition of silver particles on hydrogel fibers for antibacterial applications

    Energy Technology Data Exchange (ETDEWEB)

    Raho, Riccardo [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); CBN, Center for Biomolecular Nanotechnologies, Fondazione Istituto Italiano di Tecnologia, Via Barsanti, 73010 Arnesano, Lecce (Italy); Paladini, Federica; Lombardi, Fiorella Anna [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Boccarella, Sandro [Megatex S.p.A., Via Cima D' Aosta, 73040 Melissano, Lecce (Italy); Zunino, Benedetta [Università Cattolica del Sacro Cuore, Largo Francesco Vito 1, 00198 Roma (Italy); Pollini, Mauro, E-mail: mauro.pollini@unisalento.it [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Silvertech Ltd., Via per Monteroni, 73100 Lecce (Italy)

    2015-10-01

    Silver nanoparticles (AgNPs) have attracted intensive research interest and have been recently incorporated in polymers, medical devices, hydrogels and burn dressings to control the proliferation of microorganisms. In this study a novel silver antibacterial coating was deposited for the first time on hydrogel fibers through an in-situ photo-chemical reaction. Hydrogel blends obtained by mixing different percentages of silver-treated and untreated fibers were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four different fluids, such as phosphate buffered saline (PBS), simulated body fluid (SBF), chemical simulated wound fluid (cSWF), and deionized water (DI water), were used for evaluating the swelling properties. The results obtained confirmed that the presence of silver did not affect the properties of the hydrogel. Moreover, the results obtained through inductively coupled plasma mass spectrometry (ICP-MS) demonstrated very low silver release values, thus indicating the perfect adhesion of the silver coating to the substrate. Good antibacterial capabilities were demonstrated by any hydrogel blend on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through agar diffusion tests and optical density readings. - Highlights: • An innovative nano-silver deposition technique was adopted on hydrogel fibers. • Antibacterial effects was verified by agar diffusion and optical density tests. • The swelling properties were investigated using 4 different fluids. • Hydrogel blends with different percentages of silver-treated fibers were compared.

  8. Green roofs for a drier world: effects of hydrogel amendment on substrate and plant water status.

    Science.gov (United States)

    Savi, Tadeja; Marin, Maria; Boldrin, David; Incerti, Guido; Andri, Sergio; Nardini, Andrea

    2014-08-15

    Climate features of the Mediterranean area make plant survival over green roofs challenging, thus calling for research work to improve water holding capacities of green roof systems. We assessed the effects of polymer hydrogel amendment on the water holding capacity of a green roof substrate, as well as on water status and growth of Salvia officinalis. Plants were grown in green roof experimental modules containing 8 cm or 12 cm deep substrate (control) or substrate mixed with hydrogel at two different concentrations: 0.3 or 0.6%. Hydrogel significantly increased the substrate's water content at saturation, as well as water available to vegetation. Plants grown in 8 cm deep substrate mixed with 0.6% of hydrogel showed the best performance in terms of water status and membrane integrity under drought stress, associated to the lowest above-ground biomass. Our results provide experimental evidence that polymer hydrogel amendments enhance water supply to vegetation at the establishment phase of a green roof. In particular, the water status of plants is most effectively improved when reduced substrate depths are used to limit the biomass accumulation during early growth stages. A significant loss of water holding capacity of substrate-hydrogel blends was observed after 5 months from establishment of the experimental modules. We suggest that cross-optimization of physical-chemical characteristics of hydrogels and green roof substrates is needed to improve long term effectiveness of polymer-hydrogel blends.

  9. Radiation processing of indigenous natural polymers. Properties of radiation modified blends from sago-starch for biodegradable composite

    Energy Technology Data Exchange (ETDEWEB)

    Ghazali, Z.; Dahlan, K.Z. [Malaysian Institute for Nuclear and Technology Research (MINT), Bangi, Kajang (Malaysia); Wongsuban, B.; Idris, S.; Muhammad, K. [Universiti Putra Malaysia, Faculty of Food Science and Biotechnology, Department of Food Science, Serdang (Malaysia)

    2001-03-01

    Research and development on biodegradable polymer blends and composites have gained wider interest to offer alternative eco-friendly products. Natural polysaccharide such as sago-starch offers the most promising raw material for the production of biodegradable composites. The potential of sago, which is so abundant in Malaysia, to produce blends for subsequent applications in composite material, was evaluated and explored. Blends with various formulations of sago starch and polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP) polymers were prepared and subjected to radiation modification using electron beam irradiation. The effect of irradiation on the sago and its blends was evaluated and their properties were characterized. The potential of producing composite from sago blends was explored. Foams from these blends were produced using microwave oven while films were produced through casting method. The properties such as mechanical, water absorption, expansion ratio, and biodegradability were characterized and reported in this paper. (author)

  10. 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)

  11. Bicomponent electrospinning to fabricate three-dimensional hydrogel-hybrid nanofibrous scaffolds with spatial fiber tortuosity.

    Science.gov (United States)

    Jin, Gyuhyung; Lee, Slgirim; Kim, Seung-Hyun; Kim, Minhee; Jang, Jae-Hyung

    2014-12-01

    Electrospun fibrous mats have emerged as powerful tissue engineering scaffolds capable of providing highly effective and versatile physical guidance, mimicking the extracellular environment. However, electrospinning typically produces a sheet-like structure, which is a major limitation associated with current electrospinning technologies. To address this challenge, highly porous, volumetric hydrogel-hybrid fibrous scaffolds were fabricated by one Taylor cone-based side-by-side dual electrospinning of poly (ε-caprolactone) (PCL) and poly (vinyl pyrrolidone) (PVP), which possess distinct properties (i.e., hydrophobic and hydrogel properties, respectively). Immersion of the resulting scaffolds in water induced spatial tortuosity of the hydrogel PVP fibers while maintaining their aligned fibrous structures in parallel with the PCL fibers. The resulting conformational changes in the entire bicomponent fibers upon immersion in water led to volumetric expansion of the fibrous scaffolds. The spatial fiber tortuosity significantly increased the pore volumes of electrospun fibrous mats and dramatically promoted cellular infiltration into the scaffold interior both in vitro and in vivo. Harmonizing the flexible PCL fibers with the soft PVP-hydrogel layers produced highly ductile fibrous structures that could mechanically resist cellular contractile forces upon in vivo implantation. This facile dual electrospinning followed by the spatial fiber tortuosity for fabricating three-dimensional hydrogel-hybrid fibrous scaffolds will extend the use of electrospun fibers toward various tissue engineering applications.

  12. PVP/PEG/Carrageenan/Silver acetate hydrogels by {gamma}-ray

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Youn Mook; Youn, Young; Gwon, Hui Jeong; Park, Jong Seok; Nho, Young Chang [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2010-03-15

    In recent day, there is much interest in the biocidal activity of silver since silver is known to be safe and effective as disinifectant and biocidal material against coliforms and viruses. In this study, hydrogels containing silver acetate as antibacterial agent have been prepared using gamma rays irradiation. The hydrogels are composed of poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG), carrageenan and silver acetate. The concentration of solution was 9 wt%. The ratio of PVP: PEG: carrageenan was 6:1:2. The concentration of the silver acetate were 0,0.01, 0.03, 0.05 and 0.07% and Gamma irradiation dose was 25 kGy. The Gamma irradiation dose in hydrogels with 0.01% silver acetate were 20 kGy, 35 kGy, 50 kGy, 65 kGy, and 80 kGy. The results showed that 0.01% silver acetate concentration of hydrogels by 25 kGy irradiation dose showed the highest antibacterial activity against E. coli and Staphylococcus aureus. Moreover, antibacterial activity of various Gamma irradiation dose in hydrogels treated 0.01% silver acetate showed highest 35 kGy irradiation dose against Staphylococcus aureus.

  13. Injectable thermo-responsive hydrogel composed of xanthan gum and methylcellulose double networks with shear-thinning property.

    Science.gov (United States)

    Liu, Zhijia; Yao, Ping

    2015-11-01

    Injectable hydrogel precursor solution was prepared by physical blend of xanthan gum (XG) and methylcellulose (MC) in aqueous solution. Due to the formation of XG network composed of XG double helical strand structure, XG/MC blend was a high viscous solution with good shear-thinning property at room temperature. When the temperature was changed from 23 to 37 °C, thermo-responsive MC network formed, which caused XG/MC blend solution to gelate. The gelation time and storage modulus of the blend can be tuned by XG and/or MC concentrations. Both in vitro and in vivo investigations revealed that the blend solution immediately recovered its high viscosity and rapidly formed hydrogel at body temperature after injection using a syringe. In vivo biocompatibility and biodegradability of the hydrogel were validated by implantation of the hydrogel in rats. In vitro investigation demonstrated that XG/MC blend is a promising injectable hydrogel material for long-term drug delivery.

  14. ON COPOLYMERIZATION KINETICS OF N-VINYL PYRROLIDONE METHYL METHACRYLATE AT HIGH CONVERSION

    Institute of Scientific and Technical Information of China (English)

    WEN Jianyie; Sun Yishi

    1988-01-01

    In this work, Fourier transform infrared spectroscopy was used to study the copolymerization kinetics of N-vinyl pyrrolidone-methyl methacrylate (VPMMA) at high conversion. Through computer simulation,copolymerization rate equation based on the free volume theory, diffusion theory and modified MH model was established. The activation energy of copolymerization was also estimated.

  15. Study on antibacterial activity of hydrogel from irradiated silk protein

    Energy Technology Data Exchange (ETDEWEB)

    Bunnak, J.; Chaisupakitsin, M. [King Mongkut' s Institute of Technology Lardkrabang, Bangkok (Thailand)

    2001-03-01

    Hydrogels for biomedical application were prepared from solution blends of 3% silk protein and 3%, 10% poly (vinyl alcohol) (PVA) and followed with irradiation. Mixture of hydrogels were gamma irradiated at 10, 20, 30, 40 and 50 kGy under N{sub 2} atmosphere. To clarify anti-bacterial activity of hydrogels, modified of the Agar disk diffusion method and American Association of Textile Chemists and Colorists, AATCC Test Method 90-1977, were carried out. The four kinds of bacteria such as Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis, were used. It was found that a 1:3 volume ratio of 3% silk protein and 3% PVA respectively, at 50 kGy irradiation, is suitable conditions for preparation hydrogels and trend to indicate the highest of an antibacterial activity against E. coli, B. subtilis and S. aureus. However the antibacterial activity of hydrogels against S. epidermidis was not clearly. These results are very useful to expand the application of hydrogel from irradiated silk protein to the medical products. (author)

  16. Physically crosslinked composite hydrogels of PVA with natural macromolecules: structure, mechanical properties, and endothelial cell compatibility.

    Science.gov (United States)

    Liu, Y; Vrana, N E; Cahill, P A; McGuinness, G B

    2009-08-01

    Polyvinyl alcohol (PVA) hydrogels have been considered potentially suitable for applications as engineered blood vessels because of their structure and mechanical properties. However, PVA's hydrophilicity hinders its capacity to act as a substrate for cell attachment. As a remedy, PVA was blended with chitosan, gelatin, or starch, and hydrogels were formed by subjecting the solutions to freeze-thaw cycles followed by coagulation bath immersion. The structure-property relationships for these hydrogels were examined by measurement of their swelling, rehydration, degradation, and mechanical properties. For the case of pure PVA hydrogels, the equilibrium swelling ratio was used to predict the effect of freeze thaw cycles and coagulation bath on average molecular weights between crosslinks and on mesh size. For all hydrogels, trends for the reswelling ratio, which is indicative of the crosslinked polymer fraction, were consistent with relative tensile properties. The coagulation bath treatment increased the degradation resistance of the hydrogels significantly. The suitability of each hydrogel for cell attachment and proliferation was examined by protein adsorption and bovine vascular endothelial cell culture experiments. Protein adsorption and cell proliferation was highest on the PVA/gelatin hydrogels. This study demonstrates that the potential of PVA hydrogels for artificial blood vessel applications can be improved by the addition of natural polymers, and that freeze-thawing and coagulation bath treatment can be utilized for fine adjustment of the physical characteristics.

  17. A robust, highly stretchable supramolecular polymer conductive hydrogel with self-healability and thermo-processability

    Science.gov (United States)

    Wu, Qian; Wei, Junjie; Xu, Bing; Liu, Xinhua; Wang, Hongbo; Wang, Wei; Wang, Qigang; Liu, Wenguang

    2017-01-01

    Dual amide hydrogen bond crosslinked and strengthened high strength supramolecular polymer conductive hydrogels were fabricated by simply in situ doping poly (N-acryloyl glycinamide-co-2-acrylamide-2-methylpropanesulfonic) (PNAGA-PAMPS) hydrogels with PEDOT/PSS. The nonswellable conductive hydrogels in PBS demonstrated high mechanical performances—0.22–0.58 MPa tensile strength, 1.02–7.62 MPa compressive strength, and 817–1709% breaking strain. The doping of PEDOT/PSS could significantly improve the specific conductivities of the hydrogels. Cyclic heating and cooling could lead to reversible sol-gel transition and self-healability due to the dynamic breakup and reconstruction of hydrogen bonds. The mending hydrogels recovered not only the mechanical properties, but also conductivities very well. These supramolecular conductive hydrogels could be designed into arbitrary shapes with 3D printing technique, and further, printable electrode can be obtained by blending activated charcoal powder with PNAGA-PAMPS/PEDOT/PSS hydrogel under melting state. The fabricated supercapacitor via the conducting hydrogel electrodes possessed high capacitive performances. These cytocompatible conductive hydrogels have a great potential to be used as electro-active and electrical biomaterials.

  18. A robust, highly stretchable supramolecular polymer conductive hydrogel with self-healability and thermo-processability

    Science.gov (United States)

    Wu, Qian; Wei, Junjie; Xu, Bing; Liu, Xinhua; Wang, Hongbo; Wang, Wei; Wang, Qigang; Liu, Wenguang

    2017-01-01

    Dual amide hydrogen bond crosslinked and strengthened high strength supramolecular polymer conductive hydrogels were fabricated by simply in situ doping poly (N-acryloyl glycinamide-co-2-acrylamide-2-methylpropanesulfonic) (PNAGA-PAMPS) hydrogels with PEDOT/PSS. The nonswellable conductive hydrogels in PBS demonstrated high mechanical performances—0.22–0.58 MPa tensile strength, 1.02–7.62 MPa compressive strength, and 817–1709% breaking strain. The doping of PEDOT/PSS could significantly improve the specific conductivities of the hydrogels. Cyclic heating and cooling could lead to reversible sol-gel transition and self-healability due to the dynamic breakup and reconstruction of hydrogen bonds. The mending hydrogels recovered not only the mechanical properties, but also conductivities very well. These supramolecular conductive hydrogels could be designed into arbitrary shapes with 3D printing technique, and further, printable electrode can be obtained by blending activated charcoal powder with PNAGA-PAMPS/PEDOT/PSS hydrogel under melting state. The fabricated supercapacitor via the conducting hydrogel electrodes possessed high capacitive performances. These cytocompatible conductive hydrogels have a great potential to be used as electro-active and electrical biomaterials. PMID:28134283

  19. Electromechanical response of silk fibroin hydrogel and conductive polycarbazole/silk fibroin hydrogel composites as actuator material.

    Science.gov (United States)

    Srisawasdi, Thanida; Petcharoen, Karat; Sirivat, Anuvat; Jamieson, Alexander M

    2015-11-01

    Pure silk fibroin (SF) hydrogel and polycarbazole/silk fibroin (SF/PCZ) hydrogels were fabricated by solvent casting technique to evaluate electromechanical responses, dielectric properties, and cantilever deflection properties as functions of electric field strength, SF concentration, glutaraldehyde concentration, and PCZ concentration in the blends. Electromechanical properties were characterized in oscillatory shear mode at electric field strengths ranging from 0 to 600V/mm and at a temperature of 27°C. For both the pristine SF and SF/PCZ hydrogels, the storage modulus response (ΔG') and the storage modulus sensitivity (ΔG'/G'0) increased dramatically with increasing electric field strength. The pristine hydrogel possessed the highest storage modulus sensitivity value of 5.87, a relatively high value when compared with other previously studied electroactive polymers. With the addition of conductive PCZ in SF hydrogel, the storage modulus sensitivity and the relative dielectric constant decreased; the conductive polymer thus provided the softening effect under electric field. In the deflection response, the dielectrophoresis force and deflection distance increased monotonically with electric field strength, where the pure SF hydrogel showed the highest deflection distance and dielectrophoresis force.

  20. Synthesis and characterization of nanocomposite polymer blend electrolyte thin films by spin-coating method

    Science.gov (United States)

    Chapi, Sharanappa; Niranjana, M.; Devendrappa, H.

    2016-05-01

    Solid Polymer blend electrolytes based on Polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with zinc oxide nanoparticles (ZnO NPs; Synthesized by Co-precipitation method) thin films have prepared at a different weight percent using the spin-coating method. The complexation of the NPs with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The variation in film morphology was examined by polarized optical micrographs (POMs). The thermal behavior of blends was investigated under non-isothermal conditions by differential thermal analyses (DTA). A single glass transition temperature for each blend was observed, which supports the existence of compatibility of such system. The obtained results represent that the ternary based thin films are prominent materials for battery and optoelectronic device applications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mira; Kim, Byoung-Suhk [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Shin, Hye Kyoung [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Kim, Hak-Yong, E-mail: khy@jbnu.ac.kr [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2013-12-01

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

  2. 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.

  3. Controlled Transdermal Iontophoresis by Polypyrrole/Poly(Acrylic Acid) Hydrogel

    Science.gov (United States)

    Chansai, Phithupha; Sirivat, Anuvat

    2008-03-01

    Transdermal drug delivery system delivers a drug into a body at desired site and rate. The conductive polymer-hydrogel blend between polypyrrole (PPy) doped with anionic drug and poly(acrylic acid) (PAA) were developed as a matrix/carrier of drug for the transdermal drug delivery in which the characteristic releases depend on the electrical field applied. The PAA films and their blend films were prepared by solution casting using ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. A mechanical blending of PPy particles and PAA matrix was then carried out. Drug diffusions in the blended PPy/PAA hydrogel and the non-blended one were investigated and determined by using a modified Franz-diffusion cell with an acetate buffer, pH 5.5, at 37 0C, for a period of 48 hours to determine the effects of crosslinking ratio and electric field strength. Amounts of the released drug were measured by UV-Visible spectrophotometry. The diffusion coefficient of drug was determined through the Higuchi equation via different conditions, with and without an electric field. Moreover, thermal properties and electrical conductivity of the polypyrrole and drug-loaded polypyrrole were investigated by means of the thermogravimetric analysis and by using a two-point probe meter, respectively.

  4. 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.

  5. Arginine-glycine-aspartic acid functional branched semi-interpenetrating hydrogels.

    Science.gov (United States)

    Plenderleith, Richard A; Pateman, Christopher J; Rodenburg, Cornelia; Haycock, John W; Claeyssens, Frederik; Sammon, Chris; Rimmer, Stephen

    2015-10-14

    For the first time a series of functional hydrogels based on semi-interpenetrating networks with both branched and crosslinked polymer components have been prepared and we show the successful use of these materials as substrates for cell culture. The materials consist of highly branched poly(N-isopropyl acrylamide)s with peptide functionalised end groups in a continuous phase of crosslinked poly(vinyl pyrrolidone). Functionalisation of the end groups of the branched polymer component with the GRGDS peptide produces a hydrogel that supports cell adhesion and proliferation. The materials provide a new synthetic functional biomaterial that has many of the features of extracellular matrix, and as such can be used to support tissue regeneration and cell culture. This class of high water content hydrogel material has important advantages over other functional hydrogels in its synthesis and does not require post-processing modifications nor are functional-monomers, which change the polymerisation process, required. Thus, the systems are amenable to large scale and bespoke manufacturing using conventional moulding or additive manufacturing techniques. Processing using additive manufacturing is exemplified by producing tubes using microstereolithography.

  6. 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.)

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

    Science.gov (United States)

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

    2016-10-01

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

  8. Electrospun nanofibers of poly(vinyl pyrrolidone)/Eu3+ and its photoluminescence properties

    Institute of Scientific and Technical Information of China (English)

    Shan Shan Tang; Chang Lu Shao; Shou Zhu Li

    2007-01-01

    Nanofibers of poly(vinyl pyrrolidone) (PVP)/Eu3+ with diameters of 300-900 nm were prepared by using sol-gel processing and electrospinning technique. The products were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL). The results indicated that, Eu3+ was successfully embedded in the onedimensional hybrid nanofibers, and the PVP/Eu3+ hybrid nanofibers had favorable photoluminescence properties.

  9. Bioprinting Organotypic Hydrogels with Improved Mesenchymal Stem Cell Remodeling and Mineralization Properties for Bone Tissue Engineering.

    Science.gov (United States)

    Duarte Campos, Daniela Filipa; Blaeser, Andreas; Buellesbach, Kate; Sen, Kshama Shree; Xun, Weiwei; Tillmann, Walter; Fischer, Horst

    2016-06-01

    3D-manufactured hydrogels with precise contours and biological adhesion motifs are interesting candidates in the regenerative medicine field for the culture and differentiation of human bone-marrow-derived mesenchymal stem cells (MSCs). 3D-bioprinting is a powerful technique to approach one step closer the native organization of cells. This study investigates the effect of the incorporation of collagen type I in 3D-bioprinted polysaccharide-based hydrogels to the modulation of cell morphology, osteogenic remodeling potential, and mineralization. By combining thermo-responsive agarose hydrogels with collagen type I, the mechanical stiffness and printing contours of printed constructs can be improved compared to pure collagen hydrogels which are typically used as standard materials for MSC osteogenic differentiation. The results presented here show that MSC not only survive the 3D-bioprinting process but also maintain the mesenchymal phenotype, as proved by live/dead staining and immunocytochemistry (vimentin positive, CD34 negative). Increased solids concentrations of collagen in the hydrogel blend induce changes in cell morphology, namely, by enhancing cell spreading, that ultimately contribute to enhanced and directed MSC osteogenic differentiation. 3D-bioprinted agarose-collagen hydrogels with high-collagen ratio are therefore feasible for MSC osteogenic differentiation, contrarily to low-collagen blends, as proved by two-photon microscopy, Alizarin Red staining, and real-time polymerase chain reaction.

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

    Directory of Open Access Journals (Sweden)

    Trang Vu

    2016-09-01

    Full Text Available 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

  11. 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

    2016-09-07

    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

  12. Investigations on Poly (ethylene oxide) (PEO) - blend based solid polymer electrolytes for sodium ion batteries

    Science.gov (United States)

    Koduru, H. K.; Iliev, M. T.; Kondamareddy, K. K.; Karashanova, D.; Vlakhov, T.; Zhao, X.-Z.; Scaramuzza, N.

    2016-10-01

    Polymer blend electrolytes based on Polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP), complexed with NaIO4 salt and Graphene oxide (GO) are investigated in the present report. The electrolytes are prepared by a facile solution cast technique. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) are employed to study the influence of ion-polymer interactions on the micro structural properties of blend electrolytes. Measurements of electrical conductivity of the blend polymer complexes have been performed by using complex impedance spectroscopy in the frequency range 1 Hz - 1 MHz and within the temperature range 303 K - 343 K.A study on electrical conductivity properties of GO doped ‘salt complexed electrolyte’ systems is presented.

  13. Structuring and calorie control of bakery products by templating batter with ultra melt-resistant food-grade hydrogel beads.

    Science.gov (United States)

    Thompson, Benjamin R; Horozov, Tommy S; Stoyanov, Simeon D; Paunov, Vesselin N

    2017-08-01

    We report the use of a temperature insensitive, food-grade hydrogel to reduce the caloric density of pancakes that were prepared at temperatures much higher than the boiling point of water. This cheap, facile method utilises a mixed agar-methylcellulose hydrogel, which was blended to produce a slurry of hydrogel microbeads. The pancake batter was mixed with a controlled volume percentage of slurry of hydrogel beads and cooked. From bomb calorimetry experiments, the composites were found to have a reduced caloric density that reflects the volume percentage of hydrogel beads mixed with the batter. Using this procedure, we were able to reduce the caloric density of pancakes by up to 23 ± 3% when the volume percentage of hydrogel beads initially used was 25%. The method is not limited to pancakes and could potentially be applied to various other food products. The structure and morphology of the freeze-dried pancakes and pancake-hydrogel composites were investigated and pores of a similar size to the hydrogel beads were found, confirming that the gel beads maintained their structure during the cooking process. There is scope for further development of this method by the encapsulation of nutritionally beneficial or flavour enhancing ingredients within the hydrogel beads.

  14. 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.

  15. 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.

  16. Controlled release of acetylsalicylic acid from polythiophene/carrageenan hydrogel via electrical stimulation.

    Science.gov (United States)

    Pairatwachapun, Sanita; Paradee, Nophawan; Sirivat, Anuvat

    2016-02-10

    Blends between polythiophene (PTh) and a carrageenan hydrogel were fabricated as the matrix for the electric field assisted drug release. The pristine carrageenan and the blend films were prepared by the solution casting using acetylsalicylic acid (ASA) as the anionic model drug and Mg(2+), Ca(2+), and Ba(2+) as the crosslinking agents. The ASA was released by the Fickian diffusion mechanism. The diffusion coefficient decreased with increasing crosslinking ratio or decreasing crosslinking ionic radii. The diffusion coefficients were greater with the applied electrical potentials by an order of magnitude relative to those without electric field. Moreover, the diffusion coefficients with PTh as the drug carrier were higher than those without PTh. Thus, the presence of the conductive polymer in the hydrogel blend coupled with applied electric field is shown here to drastically enhance the drug delivery rate.

  17. Preparation and Characterization of Chitosan/Agar Blended Films: Part 2. Thermal, Mechanical, and Surface Properties

    Directory of Open Access Journals (Sweden)

    Esam A. Elhefian

    2012-01-01

    Full Text Available Chitosan/agar (CS/AG films were prepared by blending different proportions of chitosan and agar (considering chitosan as the major component in solution forms. The thermal stability of the blended films was studied using thermal gravimetric analysis (TGA. It was revealed that chitosan and agar form a compatible blend. Studying the mechanical properties of the films showed a decrease in the tensile strength and elongation at break with increasing agar content. Blending of agar with chitosan at all proportions was found to form hydrogel films with enhanced swelling compared to the pure chitosan one. Static water contact angle measurements confirmed the increasing affinity of the blended films towards water suggesting that blending of agar with chitosan improves the wettability of the obtained films.

  18. Natural polysaccharides promote chondrocyte adhesion and proliferation on magnetic nanoparticle/PVA composite hydrogels.

    Science.gov (United States)

    Hou, Ruixia; Nie, Lei; Du, Gaolai; Xiong, Xiaopeng; Fu, Jun

    2015-08-01

    This paper aims to investigate the synergistic effects of natural polysaccharides and inorganic nanoparticles on cell adhesion and growth on intrinsically cell non-adhesive polyvinyl alcohol (PVA) hydrogels. Previously, we have demonstrated that Fe2O3 and hydroxyapatite (nHAP) nanoparticles are effective in increasing osteoblast growth on PVA hydrogels. Herein, we blended hyaluronic acid (HA) and chondroitin sulfate (CS), two important components of cartilage extracellular matrix (ECM), with Fe2O3/nHAP/PVA hydrogels. The presence of these natural polyelectrolytes dramatically increased the pore size and the equilibrium swelling ratio (ESR) while maintaining excellent compressive strength of hydrogels. Chondrocytes were seeded and cultured on composite PVA hydrogels containing Fe2O3, nHAP and Fe2O3/nHAP hybrids and Fe2O3/nHAP with HA or CS. Confocal laser scanning microscopy (CLSM) and cell counting kit-8 (CCK-8) assay consistently confirmed that the addition of HA or CS promotes chondrocyte adhesion and growth on PVA and composite hydrogels. Particularly, the combination of HA and CS exhibited further promotion to cell adhesion and proliferation compared with any single polysaccharide. The results demonstrated that the magnetic composite nanoparticles and polysaccharides provided synergistic promotion to cell adhesion and growth. Such polysaccharide-augmented composite hydrogels may have potentials in biomedical applications.

  19. Controlling the Plasma-Polymerization Process of N-Vinyl-2-pyrrolidone

    DEFF Research Database (Denmark)

    Norrman, Kion; Winther-Jensen, Bjørn

    2005-01-01

    N-vinyl-2-pyrrolidone was plasma-polymerized on glass substrates using a pulsed AC plasma. Pulsed AC plasma produces a chemical surface structure different from that produced by conventional RF plasma; this is ascribed to the different power regimes used. A high degree of control over the structure...... of the chemical surface was obtained using pulsed AC plasma, as shown by ToF-SIMS. It is demonstrated how the experimental conditions to some extent control the chemical structure of the plasma-polymerized film, e.g., film thickness, density of post-plasma-polymerized oligomeric chains, and the density of intact...

  20. Electrospun polyvinyl alcohol-polyvinyl pyrrolidone nanofibrous membranes for interactive wound dressing application.

    Science.gov (United States)

    Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B; Robi, P S; Srinivasan, A

    2016-01-01

    Cross-linked polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) composite nanofibrous membranes have been prepared by electrospinning. Mechanical properties of the membranes improved significantly with PVP addition. PVP improved hydrophilicity and sustainable degradation of the membranes. Biocompatibility of the membranes was assessed by in vitro culture of native skin cells (L929 fibroblast and HaCaT keratinocytes). Tests showed sustained release of the antibiotic ciprofloxacin hydrochloride monohydrate by the membranes. Further, zone of inhibition study against Staphylococcus aureus growth demonstrated protective action against external pathogenic microbes. These studies show these simple PVA-PVP nanofibrous membranes are promising interactive antibiotic-eluting wound dressing materials.

  1. Synthesis of flower-like sulfadiazine copper/polyvinyl pyrrolidone composite and its antimicrobial activities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ping [Henan University, Key Laboratory for Special Functional Materials (China); Xu, Xiangmin [Yellow River Conservancy Technical Institute (China); Li, Binjie, E-mail: lbj821@163.com [Medical School of Henan University (China); Zhao, Yanbao [Henan University, Key Laboratory for Special Functional Materials (China)

    2015-09-15

    Flower-like sulfadiazine copper/polyvinyl pyrrolidone (SD-Cu/PVP) composite was synthesized at room temperature. Its structure and morphology were investigated by X-ray powder diffraction, scanning electron microscopy, thermo gravimetric analysis, Fourier transform infrared spectrometry, and the possible forming mechanism was discussed as well. In addition, its antibacterial activity toward the bacterial strains such as Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) was evaluated by the minimum inhibitory concentration, the minimum bactericidal concentration, and cup diffusion method. Results suggested that the SD-Cu/PVP composite displayed selectively antibacterial activity for E. coli and P. aeruginosa than S. aureus.

  2. 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.

  3. High productivity bioethanol fermentation by immobilized Saccharomyces bayanus onto carboxymethylcellulose-g- poly(N-vinyl-2-pyrrolidone) beads.

    Science.gov (United States)

    Gökgöz, Murat; Yiğitoğlu, Mustafa

    2013-04-01

    Crosslinked graft copolymers of CMC with N-vinyl-2-pyrrolidone (N-VP) were prepared in different grafting yields. Saccharomyces bayanus was immobilized in the graft copolymers of carboxymethylcellulose-g-poly(N-vinyl-2-pyrrolidone) (CMC-g-PVP) for ethanol fermentation. The effects of grafting yield, initial glucose concentration, and crosslinker concentration on the yield of ethanol process was investigated. Ethanol production increased when percentage of N-vinyl-2-pyrrolidone in the graft copolymer was increased. The maximum concentration, productivity, and yield of ethanol were 98.78 g L (-1), 8.23 g L (-1) h (-1) and 0.494 g g (-1), respectively. Reusability of the immobilized yeasts was found that the materials can be used seven times without losing their activity.

  4. 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.

  5. Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

    Science.gov (United States)

    2015-01-01

    In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers. PMID:26646318

  6. Prolonged Culture of Aligned Skeletal Myotubes on Micromolded Gelatin Hydrogels

    Science.gov (United States)

    Bettadapur, Archana; Suh, Gio C.; Geisse, Nicholas A.; Wang, Evelyn R.; Hua, Clara; Huber, Holly A.; Viscio, Alyssa A.; Kim, Joon Young; Strickland, Julie B.; McCain, Megan L.

    2016-06-01

    In vitro models of skeletal muscle are critically needed to elucidate disease mechanisms, identify therapeutic targets, and test drugs pre-clinically. However, culturing skeletal muscle has been challenging due to myotube delamination from synthetic culture substrates approximately one week after initiating differentiation from myoblasts. In this study, we successfully maintained aligned skeletal myotubes differentiated from C2C12 mouse skeletal myoblasts for three weeks by utilizing micromolded (μmolded) gelatin hydrogels as culture substrates, which we thoroughly characterized using atomic force microscopy (AFM). Compared to polydimethylsiloxane (PDMS) microcontact printed (μprinted) with fibronectin (FN), cell adhesion on gelatin hydrogel constructs was significantly higher one week and three weeks after initiating differentiation. Delamination from FN-μprinted PDMS precluded robust detection of myotubes. Compared to a softer blend of PDMS μprinted with FN, myogenic index, myotube width, and myotube length on μmolded gelatin hydrogels was similar one week after initiating differentiation. However, three weeks after initiating differentiation, these parameters were significantly higher on μmolded gelatin hydrogels compared to FN-μprinted soft PDMS constructs. Similar results were observed on isotropic versions of each substrate, suggesting that these findings are independent of substrate patterning. Our platform enables novel studies into skeletal muscle development and disease and chronic drug testing in vitro.

  7. Highly water-dispersible silver sulfadiazine decorated with polyvinyl pyrrolidone and its antibacterial activities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ping; Wu, Longlong [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Li, Binjie, E-mail: lbj821@163.com [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Medical School of Henan University, Kaifeng 475004 (China); Zhao, Yanbao [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Qu, Peng [Department of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China)

    2016-03-01

    Highly water-dispersible silver sulfadiazine (SSD) was prepared by liquid phase method with polyvinyl pyrrolidone (PVP) as a surface modification agent. The structure and morphology of the PVP-modified silver sulfadiazine (P-SSD) were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared (FT-IR) spectrometry. The produced particles are ginkgo leaf-like architecture with the sizes of micron-nanometer. Due to hydrophilic PVP decorated on the surface, the P-SSD has excellent dispersion in water over a period of 24 h, which is obviously stable by comparison to that of the commercial silver sulfadiazine (C-SSD). In addition, the P-SSD exhibits good antibacterial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). - Highlights: • Polyvinyl pyrrolidone decorated silver sulfadiazine was synthesized via a one-pot protocol. • The produced particles present ginkgo leaf-like architectures with sizes of micro-nanometer. • The resulted silver sulfadiazine has highly dispersible in water over a period of 24 h. • The obtained sliver sulfadiazine exhibits excellent antibacterial activities against E. coli, P. aeruginosa and S. aureus.

  8. In-situ photo-assisted deposition of silver particles on hydrogel fibers for antibacterial applications.

    Science.gov (United States)

    Raho, Riccardo; Paladini, Federica; Lombardi, Fiorella Anna; Boccarella, Sandro; Zunino, Benedetta; Pollini, Mauro

    2015-10-01

    Silver nanoparticles (AgNPs) have attracted intensive research interest and have been recently incorporated in polymers, medical devices, hydrogels and burn dressings to control the proliferation of microorganisms. In this study a novel silver antibacterial coating was deposited for the first time on hydrogel fibers through an in-situ photo-chemical reaction. Hydrogel blends obtained by mixing different percentages of silver-treated and untreated fibers were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four different fluids, such as phosphate buffered saline (PBS), simulated body fluid (SBF), chemical simulated wound fluid (cSWF), and deionized water (DI water), were used for evaluating the swelling properties. The results obtained confirmed that the presence of silver did not affect the properties of the hydrogel. Moreover, the results obtained through inductively coupled plasma mass spectrometry (ICP-MS) demonstrated very low silver release values, thus indicating the perfect adhesion of the silver coating to the substrate. Good antibacterial capabilities were demonstrated by any hydrogel blend on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through agar diffusion tests and optical density readings.

  9. Silk fibroin/copolymer composite hydrogels for the controlled and sustained release of hydrophobic/hydrophilic drugs.

    Science.gov (United States)

    Zhong, Tianyi; Jiang, Zhijuan; Wang, Peng; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

    2015-10-15

    In the present study, a composite system for the controlled and sustained release of hydrophobic/hydrophilic drugs is described. Composite hydrogels were prepared by blending silk fibroin (SF) with PLA-PEG-PLA copolymer under mild aqueous condition. Aspirin and indomethacin were incorporated into SF/Copolymer hydrogels as two model drugs with different water-solubility. The degradation of composite hydrogels during the drug release was mainly caused by the hydrolysis of copolymers. SF with stable β-sheet-rich structure was not easily degraded which maintained the mechanical integrity of composite hydrogel. The hydrophobic/hydrophilic interactions of copolymers with model drugs would significantly alter the morphological features of composite hydrogels. Various parameters such as drug load, concentration ratio, and composition of copolymer were considered in vitro drug release. Aspirin as a hydrophilic drug could be controlled release from composite hydrogel at a constant rate for 5 days. Its release was mainly driven by diffusion-based mechanism. Hydrophobic indomethacin could be encapsulated in copolymer nanoparticles distributing in the composite hydrogel. Its sustained release was mainly degradation controlled which could last up to two weeks. SF/Copolymer hydrogel has potential as a useful composite system widely applying for controlled and sustained release of various drugs.

  10. Miscibility Studies on Polymer Blends Modified with Phytochemicals

    Science.gov (United States)

    Chandrasekaran, Neelakandan; Kyu, Thein

    2009-03-01

    The miscibility studies related to an amorphous poly(amide)/poly(vinyl pyrrolidone) [PA/PVP] blend with a crystalline phytochemical called ``Mangiferin'' is presented. Phytochemicals are plant derived chemicals which intrinsically possess multiple salubrious properties that are associated with prevention of diseases such as cancer, diabetes, cardiovascular disease, and hypertension. Incorporation of phytochemicals into polymers has shown to have very promising applications in wound healing, drug delivery, etc. The morphology of these materials is crucial to applications like hemodialysis, which is governed by thermodynamics and kinetics of the phase separation process. Hence, miscibility studies of PA/PVP blends with and without mangiferin have been carried out using dimethyl sulfoxide as a common solvent. Differential scanning calorimetry studies revealed that the binary PA/PVP blends were completely miscible at all compositions. However, the addition of mangiferin has led to liquid-liquid phase separation and liquid-solid phase transition in a composition dependent manner. Fourier transformed infrared spectroscopy was undertaken to determine specific interaction between the polymer constituents and the role of possible hydrogen bonding among three constituents will be discussed.

  11. Phenylalanine-containing cyclic dipeptides--the lowest molecular weight hydrogelators based on unmodified proteinogenic amino acids.

    Science.gov (United States)

    Kleinsmann, Alexander J; Nachtsheim, Boris J

    2013-09-14

    Cyclic dipeptides (diketopiperazines - DKPs) that are based on the proteinogenic amino acid phenylalanine in combination with serine, cysteine, glutamate, histidine and lysine are described as simple and remarkable low molecular weight hydrogelators. Blends of selected DKPs show remarkable pH-dependent properties and can be applied as easy to tune materials in drug delivery.

  12. Potential of an injectable chitosan/starch/beta-glycerol phosphate hydrogel for sustaining normal chondrocyte function.

    Science.gov (United States)

    Ngoenkam, Jatuporn; Faikrua, Atchariya; Yasothornsrikul, Sukkid; Viyoch, Jarupa

    2010-05-31

    An injectable hydrogel for chondrocyte delivery was developed by blending chitosan and starch derived from various sources with beta-glycerol phosphate (beta-GP) in the expectation that it would retain a liquid state at room temperature and gel at raised temperatures. Rheological investigation indicated that the system consisting of chitosan derived from crab shell and corn starch at 4:1 by weight ratio (1.53%, w/v of total polymers), and 6.0% (w/v) beta-GP (C/S/GP system) exhibited the sharpest sol-gel transition at 37+/-2 degrees C. The C/S/GP hydrogel was gradually degraded by 67% within 56 days in PBS containing 0.02 mg/ml lysozyme. The presence of starch in the system increased the water absorption of the hydrogel when compared to the system without starch. SEM observation revealed to the interior structure of the C/S/GP hydrogel having interconnected pore structure (average pore size 26.4 microm) whereas the pore size of the hydrogel without starch was 19.8 microm. The hydrogel also showed an ability to maintain chondrocyte phenotype as shown by cell morphology and expression of type II collagen mRNA and protein. In vivo study revealed that the gel was formed rapidly and localized at the injection site.

  13. Copolymerization of Tris(methoxyethoxyvinyl Silane with N-Vinyl Pyrrolidone: Synthesis, Characterization, and Reactivity Relationships

    Directory of Open Access Journals (Sweden)

    Ameen Hadi Mohammed

    2015-01-01

    Full Text Available Copolymer of tris(methoxyethoxyvinyl silane (TMEVS with N-vinyl pyrrolidone (NVP was synthesized by free radical polymerization in dry benzene at 70°C using benzoyl peroxide (BPO as initiator. The copolymer was characterized by viscometer, FTIR, and 1H-NMR and its thermal properties were studied by DSC and TGA. The copolymer composition was determined by elemental analysis. The monomer reactivity ratios were calculated by linearization methods proposed by Fineman-Ross and Kelen-Tudos. The intersection method was proposed by Mayo-Lewis and nonlinear method was proposed by curve-fitting procedure. The microstructure of copolymer and sequence distribution of monomers in the copolymer were calculated by statistical method.

  14. Synthesis and dielectric studies of poly (vinyl pyrrolidone) / titanium dioxide nanocomposites

    Science.gov (United States)

    Vasudevan, Prathibha; Thomas, Sunil; V, Arunkumar K.; S, Karthika; V, Unnikrishnan N.

    2015-02-01

    In this paper, we present the synthesis of poly vinyl pyrrolidone (PVP) / titanium dioxide nanocomposites via sol- gel technique. The structural and dielectric properties of the samples were also analysed in this work. PVP doped with varying concentrations of TiO2 are prepared by the sol-gel route. The prepared composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and impedance spectroscopy. XRD and TEM confirm the presence of TiO2 nanoparticles in the composites. The dielectric response and the AC electrical conductivity of the samples are investigated for the frequency range 1 kHz-2MHz at room temperature. The dielectric studies show low values for dielectric constant and loss at high frequencies.

  15. Integrated antifouling and bactericidal polymer membranes through bioinspired polydopamine/poly(N-vinyl pyrrolidone) coating

    Science.gov (United States)

    Wang, Xianghong; Yuan, Shuaishuai; Shi, Dean; Yang, Yingkui; Jiang, Tao; Yan, Shunjie; Shi, Hengchong; Luan, Shifang; Yin, Jinghua

    2016-07-01

    Polypropylene (PP) non-woven has been widely used as wound dressing; however, the hydrophobic nature of PP can initiate bacterial attachment and subsequent biofilm formation. Herein, we propose a facile approach to functionalize PP non-woven with poly(ethylene glycol) (PEG) and poly(N-vinyl pyrrolidone)-iodine complex (PVP-I). PVP and PEG were successively tethered onto PP non-woven surface via versatile bioinspired dopamine (DA) chemistry, followed by complexing iodine with PVP moieties. It was demonstrated through the field emission scanning electron microscope (SEM) and spread plate method that the as-modified PP non-woven integrated both antifouling property of PEG for suppressing bacterial adhesion, and bactericidal property of PVP-I for killing the few adherent bacteria. Meanwhile, it could greatly resist platelet and red blood cell adhesion. The integrated antifouling and bactericidal PP non-woven surfaces might have great potential in various wound dressing applications.

  16. Synthesis and Characterization of Nano Hydroxyapatite with Poly Vinyl Pyrrolidone Nano Composite for Bone Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    A. Ragu

    2014-07-01

    Full Text Available Hydroxyapatite (Ca10 (PO46(OH2 , the main mineral component of bone and teeth, is native to the human body. Hydroxyapatite (HAp is a desirable implant material due to its biocompatibility and osteoconductivity properties. In this study, nano hydroxyapatite (nHAp with poly vinyl pyrrolidone (PVP was synthesized at room temperature condition. The synthetic nano hydroxyapatite (nHAp prepared by wet chemical precipitation method was investigated. Hydroxyapatite is biocompatible with the human organism and is capable of integrating biologically into bone tissue. The synthesized sample were characterized by Fourier transformed infrared spectroscopy (FTIR, X-ray diffraction (XRD, Transmission electron microscope (TEM, Energy dispersive analysis of x-rays techniques (EDAX and Micro hardness test.

  17. Preparation and characterization of chitosan/poly(Vinyl alcohol)/poly(Vinyl pyrrolidone) electrospun fibers

    Institute of Scientific and Technical Information of China (English)

    MA Guiping; YANG Dongzhi; ZHOU Yingshan; JIN Yu; NIE Jun

    2007-01-01

    Ultrafine fibers of chitosan/poly(vinyl alcohol)/poly(vinyl pyrrolidone) (CS/PVA/PVP) were prepared via electrospinning.The structure and morphology of CS/PVA/PVP ultrafine fibers was characterized by the Fourier transform inflared (FT-IR) spectroscope and scanning electron microscope (SEM).Furthermore.the effects of the concentration of PVA,PVP and the electrospinning voltage on the morphology of ultrafine fibers were investigated by the SEM.When the concentration of PVA was at the range of 30wt%-40wt%,ultrafine fibers could be obtained.The diameter distributions of ultrafine fibers decreased when the electrospinning voltage increased from 20to 30kV. The rough surface fibers could be obtained after etching with CHCl3.

  18. Biomonitoring of exposure to N-methyl-2-pyrrolidone in workers of the automobile industry.

    Science.gov (United States)

    Meier, Swetlana; Schindler, Birgit K; Koslitz, Stephan; Koch, Holger M; Weiss, Tobias; Käfferlein, Heiko U; Brüning, Thomas

    2013-07-01

    N-methyl-2-pyrrolidone (NMP) is an important organic solvent for varnishes in industry. NMP has been previously shown to be a developmental toxicant in rodents. This study reports current exposures to NMP in the spraying department of an automobile plant using biological monitoring. Two specific metabolites, 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methyl-succinimide (2-HMSI), were analyzed in 69 urine samples of 14 workers exposed to NMP and 9 nonexposed controls. Three different working tasks ('loading' and 'cleaning' of the sprayer system and 'wiping/packing' of the sprayed materials) and three sampling times (preshift, postshift, and preshift of the following day) were studied in exposed workers. Median exposures of 5-HNMP and 2-HMSI in postshift urine of exposed workers were 0.91 and 0.52mg g(-1) creatinine, respectively, whereas median levels in controls were below the limit of detection. Decreased levels of 5-HNMP were observed in preshift urine samples on the following day (0.39mg g(-1) creatinine) in exposed workers, while the concentration of 2-HMSI did not change (0.49mg g(-1) creatinine). Highest exposures occurred during sprayer cleaning with a maximum level of 8.31mg g(-1) creatinine of 5-HNMP in postshift urine. In contrast to 'wipers/packers', no decrease in 5-HNMP could be observed in preshift urine samples on day 2 of the 'loaders' and 'cleaners'. Overall, exposure in terms of 5-HNMP postshift and 2-HMSI preshift of the following day were well below the current biological limit values of the European Union (70 and 20mg g(-1) creatinine). Our results provide initial data on NMP exposure in the automobile industry and suggest that the analysis of 5-HNMP in preshift samples also provides essential information, particularly in situations involving direct handling of liquid NMP-containing formulations.

  19. Diffusion and structure of water in polymers containing N-vinyl-2-pyrrolidone.

    Science.gov (United States)

    Wan, Ling-Shu; Huang, Xiao-Jun; Xu, Zhi-Kang

    2007-02-08

    Poly(N-vinyl-2-pyrrolidone) (PVP), a water-soluble polymer, is known for its excellent biocompatibility. It is generally recognized that the properties of polymers may be profoundly affected by the structure of water absorbed in them. In this study, Fourier transform infrared (FT-IR) in attenuated total reflection (ATR) and transmission mode was performed to examine the diffusion and structure of water in PVP and its copolymers. The obtained spectra were analyzed using two-dimensional (2D) IR with the aid of density functional theory (DFT) calculations. The 2D IR of time-resolved FT-IR/ATR spectra shows that type II water between 3300 and 3500 cm(-1) occurs earlier during the water absorption process, which is also demonstrated by transmission FT-IR at the initial stage of water absorption. Conversely, type II water changes last when desorption takes place. Results from DFT calculations indicate that type II water might be monomeric or dimeric water molecules interacting with a carbonyl group in the pyrrolidone moiety. Furthermore, it is found that vibrations less than 3300 cm(-1) (type I water) arise from water molecules involved in a carbonyl group interacting with more than two water molecules. It is reasonable that the transmission FT-IR spectra of film with an extra low water amount hardly show vibration bands below 3300 cm(-1); however, this region is distinct in the FT-IR/ATR spectra of fully swollen film. In addition, vibration bands between 3800 and 3500 cm(-1) (type III water) are assigned to free water or water with relatively weak hydrogen bonding, as supported by the transmission FT-IR spectra of polyacrylonitrile (PAN) and the calculation results. Therefore, the diffusion process and the structures of water in PVP and its copolymers can be successfully accessed on the basis of the 2D IR analysis and DFT calculations.

  20. Novel hydrogels of chitosan and poly(vinyl alcohol)-g-glycolic acid copolymer with enhanced rheological properties.

    Science.gov (United States)

    Lejardi, A; Hernández, R; Criado, M; Santos, Jose I; Etxeberria, A; Sarasua, J R; Mijangos, C

    2014-03-15

    Poly(vinyl alcohol) (PVA) has been grafted with glycolic acid (GL), a biodegradable hydroxyl acid to yield modified poly(vinyl alcohol) (PVAGL). The formation of hydrogels at pH = 6.8 and physiological temperature through blending chitosan (CS) and PVAGL at different concentrations has been investigated. FTIR, DOSY NMR and oscillatory rheology measurements have been carried out on CS/PVAGL hydrogels and the results have been compared to those obtained for CS/PVA hydrogels prepared under the same conditions. The experimental results point to an increase in the number of interactions between chitosan and PVAGL in polymer hydrogels prepared with modified PVA. The resulting materials with enhanced elastic properties and thixotropic behavior are potential candidates to be employed as injectable materials for biomedical applications.

  1. Self-Adjustable Adhesion of Polyampholyte Hydrogels.

    Science.gov (United States)

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

    2015-12-02

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

  2. Stretchable Hydrogel Electronics and Devices.

    Science.gov (United States)

    Lin, Shaoting; Yuk, Hyunwoo; Zhang, Teng; Parada, German Alberto; Koo, Hyunwoo; Yu, Cunjiang; Zhao, Xuanhe

    2016-06-01

    Stretchable hydrogel electronics and devices are designed by integrating stretchable conductors, functional chips, drug-delivery channels, and reservoirs into stretchable, robust, and biocompatible hydrogel matrices. Novel applications include a smart wound dressing capable of sensing the temperatures of various locations on the skin, delivering different drugs to these locations, and subsequently maintaining sustained release of drugs.

  3. Hydrogels with micellar hydrophobic (nanodomains

    Directory of Open Access Journals (Sweden)

    Miloslav ePekař

    2015-01-01

    Full Text Available Hydrogels containing hydrophobic domains or nanodomains, especially of the micellar type, are reviewed. Examples of the reasons for introducing hydrophobic domains into hydrophilic gels are given; typology of these materials is introduced. Synthesis routes are exemplified and properties of a variety of such hydrogels in relation with their intended applications are described. Future research needs are identified briefly.

  4. Improving the controlled delivery formulations of caffeine in alginate hydrogel beads combined with pectin, carrageenan, chitosan and psyllium.

    Science.gov (United States)

    Belščak-Cvitanović, Ana; Komes, Draženka; Karlović, Sven; Djaković, Senka; Spoljarić, Igor; Mršić, Gordan; Ježek, Damir

    2015-01-15

    Alginate-based blends consisting of carrageenan, pectin, chitosan or psyllium husk powder were prepared for assessment of the best formulation aimed at encapsulation of caffeine. Alginate-pectin blend exhibited the lowest viscosity and provided the smallest beads. Alginate-psyllium husk blend was characterised with higher viscosity, yielding the largest bead size and the highest caffeine encapsulation efficiency (83.6%). The release kinetics of caffeine indicated that the porosity of alginate hydrogel was not reduced sufficiently to retard the diffusion of caffeine from the beads. Chitosan coated alginate beads provided the most retarded release of caffeine in water. Morphological characteristics of beads encapsulating caffeine were adversely affected by freeze drying. Bitterness intensity of caffeine-containing beads in water was the lowest for alginate-psyllium beads and chitosan coated alginate beads. Higher sodium alginate concentration (3%) for production of hydrogel beads in combination with psyllium or chitosan coating would present the most favourable carrier systems for immobilization of caffeine.

  5. 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.

  6. MESO—STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhongYang; Jian-huaRong; DanLi

    2003-01-01

    Meso-structured(opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods:post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers.A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color,which is important in designing tunable photonic crystals.Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed.The catalytic effect of acid groups in the templates was emphasized for a preferential formation of TiO2 in the region containing acid groups,which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  7. MESO-STRUCTURED POLYMERIC HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhong Yang; Jian-hua Rong; Dan Li

    2003-01-01

    Meso-structured (opal and inverse opal) polymeric hydrogels of varied morphology and composition were prepared by using two methods: post-modification of the template-synthesized structured polymers and templatepolymerization of functional monomers. A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fast pH response by changing color, which is important in designing tunable photonic crystals. Template effects of the hydrogels on controlling structure of the template-synthesized inorganic materials were discussed. The catalytic effect of acid groups inthe templates was emphasized for a preferential formation of TiO2 in the region containing acid groups, which allowed duplicating inorganic colloidal crystals from colloidal crystal hydrogels (or macroporous products from macroporous hydrogels) via one step duplication.

  8. Chemical and physical properties of poly (vinyl alcohol) hydrogel films formed by irradiation

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Chemical and physical properties of poly(vinyl alcohol)(PVA) hydrogel films were investigated as a function of production factors.The experimental results show that the gel fraction dependsstrongly on the radiation dose, the degree of swelling is inverselydependent on the concentration of PVA solution, the tensile strengthdepends mainly on the PVA blending ratio and the elongation at breakis inversely dependent on the radiation dose.

  9. Determination of N-vinyl-2-pyrrolidone and N-methyl-2-pyrrolidone in drugs using polypyrrole-based headspace solid-phase microextraction and gas chromatography-nitrogen-phosphorous detection.

    Science.gov (United States)

    Mehdinia, Ali; Ghassempour, Alireza; Rafati, Hasan; Heydari, Rouhollah

    2007-03-21

    A headspace solid-phase microextraction and gas chromatography-nitrogen-phosphorous detection (HS-SPME-GC-NPD) method using polypyrrole (PPy) fibers has been introduced to determine two derivatives of pyrrolidone; N-vinyl-2-pyrrolidone (NVP) and N-methyl-2-pyrrolidone (NMP). Two types of PPy fibers, prepared using organic and aqueous media, were compared in terms of extraction efficiency and thermal stability. It was found that PPy film prepared using organic medium (i.e. acetonitrile) had higher extraction efficiency and more thermal stability compared to the film prepared in aqueous medium. To enhance the sensitivity of HS-SPME, the effects of pH, ionic strength, extraction time, extraction temperature and the headspace volume on the extraction efficiency were optimized. Using the results of this research, high sensitivity and selectivity had been achieved due to the combination of the high extraction efficiency of PPy film prepared in organic medium and the high sensitivity and selectivity of nitrogen-phosphorous detection. Linear range of the analytes was found to be between 1.0 and 1000 microg L(-1) with regression coefficients (R(2)) of 0.998 and 0.997 for NVP and NMP, consequently. Limits of detection (LODs) were 0.074 and 0.081 microg L(-1) for NVP and NMP, respectively. Relative standard deviation (R.S.D.) for five replications of analyses was found to be less than 6.0%. In real samples the mean recoveries were 94.81% and 94.15% for NVP and NMP, respectively. The results demonstrated the suitability of the HS-SPME technique for analyzing NVP and NMP in two different pharmaceutical matrices. In addition, the method was used for simultaneous detection of NVP, 2-pyrrolidone (2-Pyr), gamma-butyrolactone (GBL) and ethanolamine (EA) compounds.

  10. Oral drug delivery system based on interpolymer complex formation between poly(acrylic acid) and poly(vinyl pyrrolidone-co-vinyl acetate)

    CSIR Research Space (South Africa)

    Germishuizen, A

    2005-07-01

    Full Text Available system based on interpolymer complex formation between poly(acrylic acid) and poly(vinyl pyrrolidone-co-vinyl acetate) 13 July 2005 André Germishuizen Supporting the Manufacturing and Materials Industry in its quest for global competitiveness CSIR... approved polymers square4 Polyacids - crosslinked poly(acrylic acid) (PAA) - poly(methacrylic acid) (PMAA) - poly(vinyl acetate phthalate) (PVAP) - cellulose acetate phthalate (CAP) square4 Polybases - poly(vinyl pyrrolidone-co-vinyl acetate) (PVP...

  11. Effect of Added Poly (vinyl pyrrolidone) during Condensation on Properties of Poly(p-phenylene terephthalamide) Pulp

    Institute of Scientific and Technical Information of China (English)

    LI Jin-chun; YOU Xiu-lan; CAO Yu-tong; LIU Zhao-feng

    2009-01-01

    Poly (p-phenylene terephthalamide) (PPTA) pulp was prepared by polycondensation of the p-phenylene diamine (PPDA) with terephthaloyl chloride (TPC) in the completely anhydrous solvent system of N-methyl pyrrolidone (NMP) having calcium chloride, in the presence of poly (vinyl pyrrolidone) (PVP) having a viscosity average molecular weight lower than 40 000. It was confirmed that the polycondensation could be accelerated, the inherent viscosity of the polymer could be increased, and the polymers could be fibrillated more easily by the addition of the PVP. FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps. The morphology of the resultant pulps, the effect of viscosity average molecular weight, amount and adding mode of PVP on inherent viscosity, specific surface area,and mean length of the resultant pulps were discussed in detail. And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.

  12. 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)

  13. Silk fibroin membranes from solvent-crystallized silk fibroin/gelatin blends: Effects of blend and solvent composition

    Energy Technology Data Exchange (ETDEWEB)

    Gil, Eun S. [Fiber and Polymer Science Program, North Carolina State University, Raleigh, NC 27695 (United States); Frankowski, David J. [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Hudson, Samuel M. [Fiber and Polymer Science Program, North Carolina State University, Raleigh, NC 27695 (United States); Spontak, Richard J. [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695 (United States) and Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States)]. E-mail: Rich_Spontak@ncsu.edu

    2007-04-15

    Protein membranes have been prepared by mixing gelatin (G) with Bombyx mori silk fibroin (SF) and using aqueous methanol (MeOH) to induce SF crystallization. Amorphous blends of these polymers appear quasi-homogeneous, as discerned from visual observation, electron microscopy and Fourier-transform infrared (FTIR) spectroscopy. Upon subsequent exposure to aqueous MeOH, SF undergoes a conformational change from random-coil to {beta}-sheet. This transformation occurs in pure SF, as well as in each of the G/SF blends, as discerned from FTIR spectroscopy and thermal calorimetry. The influence of MeOH-induced SF crystallization on structure and property development has been measured as functions of blend and solvent composition. By preserving a support scaffold above the G helix-to-coil transition temperature, the formation of crystalline SF networks in G/SF blends can be used to stabilize G-based hydrogels or generate SF membranes for biomaterial, pharmaceutical and gas-separation purposes. The present study not only examines the properties of G/SF blends before and after SF crystallization, but also establishes the foundation for future research into thermally-responsive G/SF bioconjugates.

  14. Syneresis in agar hydrogels.

    Science.gov (United States)

    Boral, Shilpi; Saxena, Anita; Bohidar, H B

    2010-03-01

    Agar hydrogels exhibit syneresis which creates internal osmotic stress on the physical network. It was observed that such a stress gives rise to characteristic pulsating modes (breathing modes). Experiments carried over a period of 60-day revealed that the network deformations grew monotonously when the solvent released by syneresis was removed periodically from gel surface. However, when the solvent was not withdrawn, the gel exhibited very slowly relaxing breathing modes. The swelling-deswelling dynamics has been discussed in the generalized framework of a dissipative damped oscillator.

  15. A Better Blend

    Science.gov (United States)

    Demski, Jennifer

    2010-01-01

    In May 2009, the US Department of Education released a meta-analysis of effectiveness studies of online, face-to-face, and blended learning models. The analysis found that online learning produced better student outcomes than face-to-face classes, and that blended learning offered an even "larger advantage" over face-to-face. The hybrid approach…

  16. Blended Learning Design

    DEFF Research Database (Denmark)

    Pedersen, Lise

    2015-01-01

    University College Lillebaelt has decided that 30 percent of all educational elements must be generated as blended learning by the end of the year 2015 as part of a modernization addressing following educational needs: 1. Blended learning can help match the expectations of the future students who...... have grown up in digitized homes and schools. 2. Blended learning helps individualization and differentiation. The students can organize their own learning paths – decide for themselves where and when to study, which paths to follow and in what tempo. 3. Blended learning helps provide resources...... learning. 4. Blended learning can contribute to supporting and improving efficiency of educational efforts. This can for instance be done through programmes for several classes by using video conferencing, allocating traditional face to face teaching to synchronous and asynchronous study activities produce...

  17. Cross-linked β-cyclodextrin and carboxymethyl cellulose hydrogels for controlled drug delivery of acyclovir

    Science.gov (United States)

    Malik, Nadia Shamshad; Ahmad, Mahmood; Minhas, Muhammad Usman

    2017-01-01

    To explore the potential role of polymers in the development of drug-delivery systems, this study investigated the use of β-cyclodextrin (β-CD), carboxymethyl cellulose (CMC), acrylic acid (AA) and N’ N’-methylenebis-acrylamide (MBA) in the synthesis of hydrogels for controlled drug delivery of acyclovir (ACV). Different proportions of β-CD, CMC, AA and MBA were blended with each other to fabricate hydrogels via free radical polymerization technique. Fourier transform infrared spectroscopy (FTIR) revealed successful grafting of components into the polymeric network. Thermal and morphological characterization confirmed the formation of thermodynamically stable hydrogels having porous structure. The pH-responsive behaviour of hydrogels has been documented by swelling dynamics and drug release behaviour in simulated gastrointestinal fluids. Drug release kinetics revealed controlled release behaviour of the antiviral drug acyclovir in developed polymeric network. Cross-linked β-cyclodextrin and carboxymethyl cellulose hydrogels can be used as promising candidates for the design and development of controlled drug-delivery systems. PMID:28245257

  18. Gelatin-based hydrogel for vascular endothelial growth factor release in peripheral nerve tissue engineering.

    Science.gov (United States)

    Gnavi, S; di Blasio, L; Tonda-Turo, C; Mancardi, A; Primo, L; Ciardelli, G; Gambarotta, G; Geuna, S; Perroteau, I

    2017-02-01

    Hydrogels are promising materials in regenerative medicine applications, due to their hydrophilicity, biocompatibility and capacity to release drugs and growth factors in a controlled manner. In this study, biocompatible and biodegradable hydrogels based on blends of natural polymers were used in in vitro and ex vivo experiments as a tool for VEGF-controlled release to accelerate the nerve regeneration process. Among different candidates, the angiogenic factor VEGF was selected, since angiogenesis has been long recognized as an important and necessary step during tissue repair. Recent studies have pointed out that VEGF has a beneficial effect on motor neuron survival and Schwann cell vitality and proliferation. Moreover, VEGF administration can sustain and enhance the growth of regenerating peripheral nerve fibres. The hydrogel preparation process was optimized to allow functional incorporation of VEGF, while preventing its degradation and denaturation. VEGF release was quantified through ELISA assay, whereas released VEGF bioactivity was validated in human umbilical vein endothelial cells (HUVECs) and in a Schwann cell line (RT4-D6P2T) by assessing VEGFR-2 and downstream effectors Akt and Erk1/2 phosphorylation. Moreover, dorsal root ganglia explants cultured on VEGF-releasing hydrogels displayed increased neurite outgrowth, providing confirmation that released VEGF maintained its effect, as also confirmed in a tubulogenesis assay. In conclusion, a gelatin-based hydrogel system for bioactive VEGF delivery was developed and characterized for its applicability in neural tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

  19. Clinically relevant hydrogel-based on hyaluronic acid and platelet rich plasma as a carrier for mesenchymal stem cells: Rheological and biological characterization.

    Science.gov (United States)

    Vadalà, Gianluca; Russo, Fabrizio; Musumeci, Maria; D'Este, Matteo; Cattani, Caterina; Catanzaro, Giuseppina; Tirindelli, Maria Cristina; Lazzari, Lorenza; Alini, Mauro; Giordano, Rosaria; Denaro, Vincenzo

    2016-12-26

    Intervertebral disc regeneration is quickly moving towards clinical applications. However, it is still missing an ideal injectable hydrogel to support mesenchymal stem cells (MSC) delivery. Herein, a new injectable hydrogel composed of platelet rich plasma (PRP) and hyaluronic acid (HA) blended with batroxobin (BTX) as gelling agent, was designed to generate a clinically relevant cell carrier for disc regeneration. PRP/HA/BTX blend was tested for rheological properties. Amplitude sweep, frequency sweep, and rotational measurements were performed and viscoelastic properties were evaluated. Human MSC encapsulated in PRP/HA/BTX hydrogel were cultured in both growing medium and medium with or without TGF-β1 up to day 21. The amount of glycosaminoglycan was evaluated. Quantitative gene expression evaluation for collagen type II, aggrecan, and Sox 9 was also performed. Rheological tests showed that the hydrogel jellifies in 15 min 20°C and in 3 min at 37°C. Biological test showed that MSCs cultured in the hydrogel maintain high cell viability and proliferation. Human MSC within the hydrogel cultured with or without TGF-β1 showed significantly higher GAG production compared to control medium. Moreover, MSCs in the hydrogel underwent differentiation to chondrocyte-like cells with TGF-β1, as shown by histology and gene expression analysis. This novel hydrogel improves viability and proliferation of MSCs supporting the differentiation process toward chondrocyte-like cells. Rheology tests showed optimal gelation kinetics at room temperature for manipulation and faster gelation after transplantation (37°C). The clinical availability of all components of the hydrogel will allow a rapid translation of this regenerative approach into the clinical scenario. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  20. Nanocomposite scaffold with enhanced stability by hydrogen bonds between collagen, polyvinyl pyrrolidone and titanium dioxide.

    Science.gov (United States)

    Li, Na; Fan, Xialian; Tang, Keyong; Zheng, Xuejing; Liu, Jie; Wang, Baoshi

    2016-04-01

    In this study, three-dimensional (3D) nanocomposite scaffolds, as potential substrates for skin tissue engineering, were fabricated by freeze drying the mixture of type I collagen extracted from porcine skin and polyvinyl pyrrolidone (PVP)-coated titanium dioxide (TiO2) nanoparticles. This procedure was performed without any cross-linker or toxic reagents to generate porosity in the scaffold. Both morphology and thermal stability of the nanocomposite scaffold were examined. The swelling behavior, mechanical properties and hydrolytic degradation of the composite scaffolds were carefully investigated. Our results revealed that collagen, PVP and TiO2 are bonded together by four main hydrogen bonds, which is an essential action for the formation of nanocomposite scaffold. Using Coasts-Redfern model, we were able to calculate the thermal degradation apparent activation energy and demonstrated that the thermal stability of nanocomposites is dependent on amount of PVP incorporated. Furthermore, SEM images showed that the collagen fibers are wrapped and stabilized on scaffolds by PVP molecules, which improve the ultimate tensile strength (UTS). The UTS of PVP-contained scaffold is four times higher than that of scaffold without PVP, whereas ultimate percentage of elongation (UPE) is decreased, and PVP can enhance the degradation resistance.

  1. Integrated antifouling and bactericidal polymer membranes through bioinspired polydopamine/poly(N-vinyl pyrrolidone) coating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianghong [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Yuan, Shuaishuai [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Shi, Dean, E-mail: deanshi2012@yahoo.com [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Yang, Yingkui; Jiang, Tao [Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Yan, Shunjie; Shi, Hengchong [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Luan, Shifang, E-mail: sfluan@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yin, Jinghua [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2016-07-01

    Graphical abstract: - Highlights: • Antifouling and bactericidal capabilities were facilely integrated into a surface via bioinspired coating. • The modification technique was very facile and universal to different types of substrate materials. • The integrated antifouling and bactericidal surfaces have great potential in wound dressing applications. - Abstract: Polypropylene (PP) non-woven has been widely used as wound dressing; however, the hydrophobic nature of PP can initiate bacterial attachment and subsequent biofilm formation. Herein, we propose a facile approach to functionalize PP non-woven with poly(ethylene glycol) (PEG) and poly(N-vinyl pyrrolidone)-iodine complex (PVP-I). PVP and PEG were successively tethered onto PP non-woven surface via versatile bioinspired dopamine (DA) chemistry, followed by complexing iodine with PVP moieties. It was demonstrated through the field emission scanning electron microscope (SEM) and spread plate method that the as-modified PP non-woven integrated both antifouling property of PEG for suppressing bacterial adhesion, and bactericidal property of PVP-I for killing the few adherent bacteria. Meanwhile, it could greatly resist platelet and red blood cell adhesion. The integrated antifouling and bactericidal PP non-woven surfaces might have great potential in various wound dressing applications.

  2. Synthesis of nano-sized perovskite-type oxide with the use of polyvinyl pyrrolidone

    Directory of Open Access Journals (Sweden)

    Tsukasa Nagai

    2014-12-01

    Full Text Available A new easy-to-use process for obtaining fine powders of lanthanum-based perovskite-type oxides (La1−xAexMO3: Ae = Ca, Sr, M = Mn, Co, Fe with a high specific surface area was successfully developed by the use of polyvinyl pyrrolidone (PVP as a dispersant. This approach made it possible to prepare a single phase of perovskite by calcining at a lower temperature (600 °C compared to conventional synthetic processes such as a solid state reaction and citrate process. SEM observations revealed that the oxide prepared with PVP was ca. 20–30 nm in size, while those prepared by the citrate process and solid state reaction were ca. 50 nm and 1 μm, respectively. Furthermore, the results of a thermal analysis in which we heated the precursors for the different reactions support the idea that PVP plays an important role in the formation of the perovskite phase at low temperature.

  3. The composition of hydrogels for cartilage tissue engineering can influence glycosaminoglycan profile

    Directory of Open Access Journals (Sweden)

    QG Wang

    2010-02-01

    Full Text Available The injectable and hydrophilic nature of hydrogels makes them suitable candidates for cartilage tissue engineering. To date, a wide range of hydrogels have been proposed for articular cartilage regeneration but few studies have quantitatively compared chondrocyte behaviour and extracellular matrix (ECM synthesis within the hydrogels. Herein we have examined the nature of ECM synthesis by chondrocytes seeded into four hydrogels formed by either temperature change, self-assembly or chemical cross-linking. Bovine articular cartilage chondrocytes were cultured for 14 days in Extracel®, Pluronic F127 blended with Type II collagen, Puramatrix® and Matrixhyal®. The discriminatory and sensitive technique of fluorophore-assisted carbohydrate electrophoresis (FACE was used to determine the fine detail of the glycosaminoglycans (GAG; hyaluronan and chondroitin sulphate. FACE analysis for chondroitin sulphate and hyaluronan profiles in Puramatrix® closely matched that of native cartilage. For each hydrogel, DNA content, viability and morphology were assessed. Total collagen and total sulphated GAG production were measured and normalised to DNA content. Significant differences were found in total collagen synthesis. By day 14, Extracel® and Puramatrix® had significantly more total collagen than Matrixhyal® (1.77±0.26 µg and 1.97±0.26 µg vs. 0.60±0.26 µg; p<0.05. sGAG synthesis occurred in all hydrogels but a significantly higher amount of sGAG was retained within Extracel® at days 7 and 14 (p<0.05. In summary, we have shown that the biochemical and biophysical characteristics of each hydrogel directly or indirectly influenced ECM formation. A detailed understanding of the ECM in the development of engineered constructs is an important step in monitoring the success of cartilage regeneration strategies.

  4. Synthetically simple, highly resilient hydrogels.

    Science.gov (United States)

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

    2012-03-12

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

  5. Electrical conductivity studies on Ammonium bromide incorporated with Zwitterionic polymer blend electrolyte for battery application

    Science.gov (United States)

    Parameswaran, V.; Nallamuthu, N.; Devendran, P.; Nagarajan, E. R.; Manikandan, A.

    2017-06-01

    Solid polymer blend electrolytes are widely studied due to their extensive applications particularly in electrochemical devices. Blending polymer makes the thermal stability, higher mechanical strength and inorganic salt provide ionic charge carrier to enhance the conductivity. In these studies, 50% polyvinyl alcohol (PVA), 50% poly (N-vinyl pyrrolidone) (PVP) and 2.5% L-Asparagine mixed with different ratio of the Ammonium bromide (NH4Br), have been synthesized using solution casting technique. The prepared PVA/PVP/L-Asparagine/doped-NH4Br polymer blend electrolyte films have been characterized by various analytical methods such as FT-IR, XRD, impedance spectroscopy, TG-DSC and scanning electron microscopy. FT-IR, XRD and TG/DSC analysis revealed the structural and thermal behavior of the complex formation between PVA/PVP/L-Asparagine/doped-NH4Br. The ionic conductivity and the dielectric properties of PVA/PVP/L-Asparagine/doped-NH4Br polymer blend electrolyte films were examined using impedance analysis. The highest ionic conductivity was found to be 2.34×10-4 S cm-1 for the m.wt. composition of 50%PVA:50%PVP:2.5%L-Asparagine:doped 0.15 g NH4Br at ambient temperature. Solid state proton battery is fabricated and the observed open circuit voltage is 1.1 V and its performance has been studied.

  6. Cytocompatible cellulose hydrogels containing trace lignin.

    Science.gov (United States)

    Nakasone, Kazuki; Kobayashi, Takaomi

    2016-07-01

    Sugarcane bagasse was used as a cellulose resource to prepare transparent and flexible cellulose hydrogel films. On the purification process from bagasse to cellulose, the effect of lignin residues in the cellulose was examined for the properties and cytocompatibility of the resultant hydrogel films. The cellulose was dissolved in lithium chloride/N,N-dimethylacetamide solution and converted to hydrogel films by phase inversion. In the purification process, sodium hydroxide (NaOH) treatment time was changed from 1 to 12h. This resulted in cellulose hydrogel films having small amounts of lignin from 1.62 to 0.68%. The remaining lignin greatly affected hydrogel properties. Water content of the hydrogel films was increased from 1153 to 1525% with a decrease of lignin content. Moreover, lower lignin content caused weakening of tensile strength from 0.80 to 0.43N/mm(2) and elongation from 45.2 to 26.5%. Also, similar tendency was observed in viscoelastic behavior of the cellulose hydrogel films. Evidence was shown that the lignin residue was effective for the high strength of the hydrogel films. In addition, scanning probe microscopy in the morphological observation was suggested that the trace lignin in the cellulose hydrogel affected the cellulose fiber aggregation in the hydrogel network. The trace of lignin in the hydrogels also influenced fibroblast cell culture on the hydrogel films. The hydrogel film containing 1.68% lignin showed better fibroblast compatibility as compared to cell culture polystyrene dish used as reference.

  7. Energy conversion in polyelectrolyte hydrogels

    Science.gov (United States)

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

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

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

    Institute of Scientific and Technical Information of China (English)

    HE Guanghua; ZHENG Hua; XIONG Fuliang

    2008-01-01

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

  9. Supramolecular hydrogels as drug delivery systems.

    Science.gov (United States)

    Saboktakin, Mohammad Reza; Tabatabaei, Roya Mahdavi

    2015-04-01

    Drug delivery from a hydrogel carrier implanted under the kidney capsule is an innovative way to induce kidney tissue regeneration and/or prevent kidney inflammation or fibrosis. We report here on the development of supramolecular hydrogels for this application. Chain-extended hydrogelators containing hydrogen bonding units in the main chain, and bifunctional hydrogelators end-functionalized with hydrogen bonding moieties, were made. The influence of these hydrogels on the renal cortex when implanted under the kidney capsule was studied. The overall tissue response to these hydrogels was found to be mild, and minimal damage to the cortex was observed, using the infiltration of macrophages, formation of myofibroblasts, and the deposition of collagen III as relevant read-out parameters. Differences in tissue response to these hydrogels could be related to the different physico-chemical properties of the three hydrogels.

  10. Patterns in swelling hydrogels

    Science.gov (United States)

    MacMinn, Chris; Bertrand, Thibault; Peixinho, Jorge; Mukhopadhyay, Shomeek

    2016-11-01

    Swelling is a process in which a porous material spontaneously grows by absorbing additional pore fluid. Polymeric hydrogels are highly deformable materials that can experience very large volume changes during swelling. This allows a small amount of dry gel to absorb a large amount of fluid, making gels extremely useful in applications from moisture control to drug delivery. However, a well-known consequence of these extreme volume changes is the emergence of a striking morphological instability. We study the transient mechanics of this instability here by combining a theoretical model with a series of simple experiments, focusing on the extent to which this instability can be controlled by manipulating the rate of swelling.

  11. MOOC Blended learning ontwikkelen

    NARCIS (Netherlands)

    Verjans, Steven

    2015-01-01

    Presentatie over het ontwerpen van leeractiviteiten (learning design) tijdens de zesde live sessie van de MOOC Blended learning ontwikkelen. Met gebruikmaking van presentatiematerialen van Diana Laurillard, Grainne Conole, Helen Beetham, Jos Fransen, Pieter Swager, Helen Keegan, Corinne Weisgerber.

  12. MOOC Blended learning ontwikkelen

    NARCIS (Netherlands)

    Verjans, Steven

    2015-01-01

    Presentatie over het ontwerpen van leeractiviteiten (learning design) tijdens de zesde live sessie van de MOOC Blended learning ontwikkelen. Met gebruikmaking van presentatiematerialen van Diana Laurillard, Grainne Conole, Helen Beetham, Jos Fransen, Pieter Swager, Helen Keegan, Corinne Weisgerber.

  13. Alginate-Collagen Fibril Composite Hydrogel.

    Science.gov (United States)

    Baniasadi, Mahmoud; Minary-Jolandan, Majid

    2015-02-16

    We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM)-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  14. Alginate-Collagen Fibril Composite Hydrogel

    Directory of Open Access Journals (Sweden)

    Mahmoud Baniasadi

    2015-02-01

    Full Text Available We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  15. Immobilization and release study of a red alga extract in hydrogel membranes; Estudo da incorporacao e liberacao de um extrato de algas vermelhas em membranas de hidrogel

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Renata Hage

    2009-07-01

    In pharmaceutical technology hydrogel is the most used among the polymeric matrices due to its wide application and functionality, primarily in drug delivery system. In view of the large advance innovations in cosmetic products, both through the introduction of new active agents as the matrices used for its controlled release, the objective of this study was to evaluate the release and immobilization of a natural active agent, the Arct'Alg in hydrogel membranes to obtain a release device for cosmetics. Arct'Alg is an aqueous extract which has excellent anti-oxidant, lipolytic, anti-inflammatory and cytostimulant action. Study on mechanical and physical-chemical properties and biocompatibility in vitro of hydrogel membranes of poly(vinyl-2- pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) obtained by ionizing radiation crosslinking have been performed. The physical-chemical characterization of polymeric matrices was carried out by gel fraction and swelling tests and biocompatibility by in vitro test of cytotoxicity by using the technique of neutral red incorporation. In the gel fraction test, both the PVP and PVA hydrogel showed a high crosslinking degree. The PVP hydrogel showed a greater percentage of swelling in relation to PVA and the cytotoxicity test of the hydrogels showed non-toxicity effect. The cytostimulation property of Arct'Alg was verified by the cytostimulation test with rabbit skin cells, it was showed an increase at about 50% of the cells when in contact with 0,5% of active agent. The hydrogel membranes prepared with 3% of Arct'Alg were subjected to the release test in an incubator at 37 degree C and aliquots collected during the test were quantified by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that the PVP hydrogel membranes released about 50% of Arct'Alg incorporated and the PVA hydrogel membranes at about 30%. In the cytostimulation test of released Arct

  16. 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

  17. 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.

  18. 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

  19. Development of a novel sodium fusidate-loaded triple polymer hydrogel wound dressing: Mechanical properties and effects on wound repair.

    Science.gov (United States)

    Jin, Sung Giu; Kim, Kyeong Soo; Kim, Dong Wuk; Kim, Dong Shik; Seo, Youn Gee; Go, Toe Gyung; Youn, Yu Seok; Kim, Jong Oh; Yong, Chul Soon; Choi, Han-Gon

    2016-01-30

    To develop a novel sodium fusidate-loaded triple polymer hydrogel dressing (TPHD), numerious polyvinyl alcohol-based (PVA) hydrogel dressings were prepared with various hydrophilic polymers using the freeze-thaw method, and their hydrogel dressing properties were assessed. Among the hydrophilic polymers tested, sodium alginate (SA) improved the swelling capacity the most, and polyvinyl pyrrolidone (PVP) provided the greatest improvement in bioadhesive stength and mechanical properties. Thus, PVA based-TPHDs were prepared using different ratios of PVP:SA. The effect of selected PVP:SA ratios on the swelling capacity, bioadhesive strength, mechanical properties, and drug release, permeation and deposition characteristics of sodium fusidate-loaded PVA-based TPHDs were assessed. As the ratio of PVP:SA increased in PVA-loaded TPHD, the swelling capacity, mechanical properties, drug release, permeation and deposition were improved. The TPHD containing PVA, PVP, SA and sodium fusidate at the weight ratio of 10/6/1/1 showed excellent hydrogel dressing properties, release, permeation and deposition of drug. Within 24h, 71.8 ± 1.3% of drug was released. It permeated 625.1 ± 81.2 μg/cm(2) through the skin and deposited of 313.8 ± 24.1 μg/cm(2) within 24h. The results of in vivo pharmacodynamic studies showed that sodium fusidate-loaded TPHD was more effective in improving the repair process than was a commercial product. Thus, this sodium fusidate-loaded TPHD could be a novel tool in wound care.

  20. Obtaining membranes for alternative treatment hydrogels of cutaneous leishmaniasis; Obtencao de membranas de hidrogeis para tratamento alternativo da leishmaniose tegumentar

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Maria Jose Alves de

    2013-07-01

    Polymeric Hydrogels formed by crosslinked polymeric chains were obtained by ionizing radiation process according to Rosiak technique. In the last 40 years the use of hydrogels has been investigated for various applications as curatives. In this work hydrogel membranes were synthesized with poly (N-2-pyrrolidone) (PVP), poly (vinyl alcohol) (PVA), chitosan and laponita clay for use as a vehicle for controlled glucantime release on the surface of skin tissues injured by leishmaniasis. Leishmaniasis is a disease caused by a protozoan parasite of the genus Leishmania transmitted by the bite of phlebotomies sandfly. The traditional treatment of patients infected by these parasites is done with pentavalent antimony in injectable form. However, these antimonates are highly toxic and cause side effects in these patients. In addition, patients with heart and kidney disease can not use this treatment. In treatment with drug delivery hydrogel membrane applied on the surface of leishmaniasis injured tissues the drug is released directly to the wound in a controlled manner, reducing the side effects. Membranes prepared in this study were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), swelling, gel fraction, infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The characterizations of cytotoxicity and drug release were made 'in vitro' and 'in vivo' with functional test according to ethical protocol of the Division of Infectious and Parasitic Diseases at the Hospital of Clinics, Sao Paulo University-School of Medicine, University. The 'in vivo' test of these membranes proved to be effective in controlled release of drugs directly into leishmaniasis damaged tissues. Results of 'in vivo' tests using PVP/PVAl / clay 1,5% and glucantime membrane showed remarkable contribution to wound reduction and cure in clinical therapy. (author)

  1. Lithium ion conducting solid polymer blend electrolyte based on bio-degradable polymers

    Indian Academy of Sciences (India)

    Natarajan Rajeswari; Subramanian Selvasekarapandian; Moni Prabu; Shunmugavel Karthikeyan; C Sanjeeviraja

    2013-04-01

    Lithium ion conducting polymer blend electrolyte films based on poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) with different Mwt% of lithium nitrate (LiNO3) salt, using a solution cast technique, have been prepared. The polymer blend electrolyte has been characterized by XRD, FTIR, DSC and impedance analyses. The XRD study reveals the amorphous nature of the polymer electrolyte. The FTIR study confirms the complex formation between the polymer and salt. The shifts in g values of 70 PVA–30 PVP blend and 70 PVA–30 PVP with different Mwt% of LiNO3 electrolytes shown by DSC thermograms indicate an interaction between the polymer and the salt. The dependence of g and conductivity upon salt concentration has been discussed. The ion conductivity of the prepared polymer electrolyte has been found by a.c. impedance spectroscopic analysis. The PVA–PVP blend system with a composition of 70 wt% PVA: 30 wt% PVP exhibits the highest conductivity of 1.58 × 10-6 Scm-1 at room temperature. Polymer samples of 70 wt% PVA–30 wt% PVP blend with different molecular weight percentage of lithium nitrate with DMSO as solvent have been prepared and studied. High conductivity of 6.828 × 10-4 Scm-1 has been observed for the composition of 70 PVA:30 PVP:25 Mwt% of LiNO3 with low activation energy 0.2673 eV. The conductivity is found to increase with increase in temperature. The temperature dependent conductivity of the polymer electrolyte follows the Arrhenius relationship which shows hopping of ions in the polymer matrix. The relaxation parameters () and () of the complexes have been calculated by using loss tangent spectra. The mechanical properties of polymer blend electrolyte such as tensile strength, elongation and degree of swelling have been measured and the results are presented.

  2. MISCIBILITY, THERMAL STABILITY AND RETENTION OF PVP FOR CROSSLINKED PVA/PVP BLENDS

    Institute of Scientific and Technical Information of China (English)

    LIANG Guomei; ZHANG Kun; FENG Rongyin

    1994-01-01

    The thermal behavior, miscibility, crystallite conformation and thermal stability of crosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSC results showed that in the blend, the crystallinity,Tm and Tc of PVA were obviously lower than those of pure PVA; the crystal growth changed from three dimensional to two dimensional and only a single Tg was detected . These facts demonstrated that this crystalline and amorphous blend have good miscibility. TG curves showed that providing the quantity of K2S2O8 added is more than 3 wt % ,in the blends PVA will form a stable CL-network, whose thermal degradation temperature was near to that of PVP. But crosslinking reaction will not take place for PVP. The processes of thermal degradation of CL-blends are based on combining both the thermal degradation of PVP and that of PVA crosslinked with corresponding quantity of K2S2O8 CL-agent, respectively.The UV measurements showed that 75 wt% of PVP may be remained in CL-blend hydrogels crosslinked by adding (3- 5 wt % )K2S2O8.This is mainly due to the stable CL-network formed and the good compatibility and proper entanglement between the composites in the CL-blends.

  3. Decreased material-activation of the complement system using low-energy plasma polymerized poly(vinyl pyrrolidone) coatings

    DEFF Research Database (Denmark)

    Andersen, T.E.; Kolmos, H.J.; Palarasah, Yaseelan

    2011-01-01

    surface. The ppVP surface is furthermore characterized physically and chemically using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR), which indicates preservation of chemical functionality by the applied plasma process. Overall, the pp......In the current study we investigate the activation of blood complement on medical device silicone rubber and present a plasma polymerized vinyl pyrrolidone (ppVP) coating which strongly decreases surface-activation of the blood complement system. We show that uncoated silicone and polystyrene...

  4. 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...

  5. Tough photoluminescent hydrogels doped with lanthanide.

    Science.gov (United States)

    Wang, Mei Xiang; Yang, Can Hui; Liu, Zhen Qi; Zhou, Jinxiong; Xu, Feng; Suo, Zhigang; Yang, Jian Hai; Chen, Yong Mei

    2015-03-01

    Photoluminescent hydrogels have emerged as novel soft materials with potential applications in many fields. Although many photoluminescent hydrogels have been fabricated, their scope of usage has been severely limited by their poor mechanical performance. Here, a facile strategy is reported for preparing lanthanide (Ln)-alginate/polyacrylamide (PAAm) hydrogels with both high toughness and photoluminescence, which has been achieved by doping Ln(3+) ions (Ln = Eu, Tb, Eu/Tb) into alginate/PAAm hydrogel networks, where Ln(3+) ions serve as both photoluminescent emitters and physical cross-linkers. The resulting hydrogels exhibit versatile advantages including excellent mechanical properties (∼ MPa strength, ≈ 20 tensile strains, ≈ 10(4) kJ m(-3) energy dissipation), good photoluminescent performance, tunable emission color, excellent processability, and cytocompatibility. The developed tough photoluminescent hydrogels hold great promises for expanding the usage scope of hydrogels.

  6. Synthesis and characterization of UV photocrosslinkable hydrogels with poly(N-vinyl-2-pyrrolidone): Determination of the network mesh size distribution

    DEFF Research Database (Denmark)

    Marizza, Paolo; Abrami, M.; Keller, Stephan Sylvest

    2016-01-01

    rheology, low field nuclear magnetic resonance spectroscopy (LF-NMR), and small angle X-ray scattering. Different irradiation doses as well as polymer and initiator concentrations were tested in the characterization. The study elucidates the relationship between different methods to estimate the mesh size...

  7. Blended Learning Environments and Suggesstions for Blended Learning Design

    Directory of Open Access Journals (Sweden)

    Funda DAĞ

    2011-06-01

    Full Text Available The number of studies in blended learning field, which has gained importance by being reinterpreted with the effect of the developments in information and communication technologies, has been increasing recently. There have been many diverse approaches in these studies on the point of defining blended learning and on the point of which components of blended learning environments need blending and how they are blended. The aim of this study is to examine national and international studies in blended learning in higher education and to make suggestions about necessary components for designing an effective blended learning environment. Within this framework the studies on blended learning, which were accessible online, were examined from the perspectives of research methods that were used, preferred e-learning environments and/or e-learning methods, preferred face to face learning/teaching strategies and the methods used in the evaluation of blended learning. In the light of the findings it is seen that blended learning should be regarded as a teaching design approach in order to create effectively blended learning environments and it is hoped that the suggestions made will be lodestar in forming blended learning models for diverse learning fields.

  8. Supporting School Leaders in Blended Learning with Blended Learning

    Science.gov (United States)

    Acree, Lauren; Gibson, Theresa; Mangum, Nancy; Wolf, Mary Ann; Kellogg, Shaun; Branon, Suzanne

    2017-01-01

    This study provides a mixed-methods case-study design evaluation of the Leadership in Blended Learning (LBL) program. The LBL program uses blended approaches, including face-to-face and online, to prepare school leaders to implement blended learning initiatives in their schools. This evaluation found that the program designers effectively…

  9. AKRO/SF: Blend System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Blend was the system used by the NMFS Alaska Regional Office to monitor groundfish catch from 1991 until 2002. The Blend system combined data from industry...

  10. Chitosan-dextran sulfate hydrogels as a potential carrier for probiotics.

    Science.gov (United States)

    Yucel Falco, Cigdem; Falkman, Peter; Risbo, Jens; Cárdenas, Marité; Medronho, Bruno

    2017-09-15

    Physical and chemical (crosslinked with genipin) hydrogels based on chitosan and dextran sulfate were developed and characterized as novel bio-materials suitable for probiotic encapsulation. The swelling of the hydrogels was dependent on the composition and weakly influenced by the pH of the media. The morphology analysis supports the swelling data showing distinct changes in microstructure depending on the composition. The viability and culturability tests showed approx. 3.6 log CFU/mL decrease of cells (L. acidophilus as model) incorporated into chemical hydrogels when compared to the number of viable native cells. However, the live/dead viability assay evidenced that a considerable amount of viable cells were still entrapped in the hydrogel network and therefore the viability is most likely underestimated. Overall, the developed systems are robust and their structure, rheology and swelling properties can be tuned by changing the blend ratio, thus constituting appealing bio-matrices for cell encapsulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Surface Modification of Polypropylene Microporous Membrane by Atmospheric-pressure Plasma Induced N-vinyl-2-pyrrolidone Graft Polymerization

    Institute of Scientific and Technical Information of China (English)

    ZHONG Shaofeng

    2012-01-01

    Membrane surfaces modified with poly(N-vinyl-2-pyrrolidone) (PNVP) can be endowed with hydrophilicity,biocompatibility and functionality.In this work,atmospheric pressure dielectric barrier discharge plasma graft polymerization of N-vinyl-2-pyrrolidone (NVP) onto polypropylene (PP) microporous membrane surface was studied.The experimental results reveal that plasma treatment conditions,such as discharge power,treatment time and adsorbed NVP amount,have remarkable effects on the grafting degree of NVP.Structural and morphological changes on the membrane surfaces were characterized by attenuated total reflection-Fourier transform infrared spectroscopy (FT-IR/ATR),X-ray photoelectron spectroscope (XPS) and field emission scanning electron microscopy (FE-SEM).Water contact angles of the membrane surfaces were also measured by the sessile drop method.Water contact angles on the membrane surfaces decrease with the increase of NVP grafting degree,which indicates an enhanced hydrophilicity for the modified membranes.The effects of grafting degrees on pure water fluxes were also measured.It is shown that pure water fluxes increase with grafting degree firstly and then decrease adversely.Finally,filtration of bovine serum albumin (BSA) solution and platelets adhesion of the PNVP modified membranes show good protein resistance and potential biocompatibility due to the enhancement of surface hydrophilicity.

  12. X-ray crystalline structures of pyrrolidone carboxyl peptidase from a hyperthermophile, Pyrococcus furiosus, and its cys-free mutant.

    Science.gov (United States)

    Tanaka, H; Chinami, M; Mizushima, T; Ogasahara, K; Ota, M; Tsukihara, T; Yutani, K

    2001-07-01

    In order to elucidate the mechanism of the thermostability of proteins from hyperthermophiles, X-ray crystalline structures of pyrrolidone carboxyl peptidase from a hyperthermophile, Pyrococcus furiosus (PfPCP), and its mutant protein with Ser substituted at Cys142 and Cys188 were determined at 2.2 and 2.7 A resolution, respectively. The obtained structures were compared with those previously reported for pyrrolidone carboxyl peptidases from a hyperthermophilie, Thermococcus litoralis (TlPCP), and from a mesophile, Bacillus amyloliquefaciens (BaPCP). The PfPCP structure is a tetramer of four identical subunits similar to that of the TlPCP and BaPCP. The largest structural changes among the three PCPs were detected in the C-terminal protrusion, which interacts with that of another subunit. A comparison of the three structures indicated that the high stability of PfPCP is caused by increases in hydrophobic interactions and hydrogen bonds, the formation of an intersubunit ion-pair network, and improvement to an ideal conformation. On the basis of the structures of the three proteins, it can be concluded that PfPCP does not have any special factors responsible for its extremely high stability and that the conformational structure of PfPCP is superior in its combination of positive and negative stabilizing factors compared with BaPCP.

  13. Human volunteer study on the inhalational and dermal absorption of N-methyl-2-pyrrolidone (NMP) from the vapour phase.

    Science.gov (United States)

    Bader, Michael; Wrbitzky, Renate; Blaszkewicz, Meinolf; Schäper, Michael; van Thriel, Christoph

    2008-01-01

    N-Methyl-2-pyrrolidone (NMP) is a versatile organic solvent frequently used for surface cleaning such as paint stripping or graffiti removal. Liquid NMP is rapidly absorbed through the skin but dermal vapour phase absorption might also play an important role for the uptake of the solvent. This particular aspect was investigated in an experimental study with 16 volunteers exposed to 80 mg/m(3) NMP for 8 h under either whole-body, i.e. inhalational plus dermal, or dermal-only conditions. Additionally, the influence of moderate physical workload on the uptake of NMP was studied. The urinary concentrations of NMP and its metabolites 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methylsuccinimide (2-HMSI) were followed for 48 h and analysed by gas chromatography-mass spectrometry (GC-MS). Percutaneous uptake delayed the elimination peak times and the apparent biological half-lives of NMP and 5-HNMP. Under resting conditions, dermal-only exposure resulted in the elimination of 71 +/- 8 mg NMP equivalents as compared to 169 +/- 15 mg for whole-body exposure. Moderate workload yielded 79 +/- 8 mg NMP (dermal-only) and 238 +/- 18 mg (whole-body). Thus, dermal absorption from the vapour phase may contribute significantly to the total uptake of NMP, e.g. from workplace atmospheres. As the concentration of airborne NMP does not reflect the body dose, biomonitoring should be carried out for surveillance purposes.

  14. Polymer Blends. Volume 1

    Science.gov (United States)

    1992-05-01

    PBI/ ULTEM NEAT RESIN MOLDING EVALUATIONS 18 2.1.3 85/15 PBI/ ULTEM COMPOSITE EVALUATIONS 22 2.1.4 FIRST GENERATION SUMMARY 26 2.2 IMPROVED PBI/"BEST...PBI 37 2.2.4 85/15 eCPBI-2/ ULTEM NEAT RESIN EVALUATIONS 42 2.2.5 SECOND GENERATION SUMMARY 45 2.3 IMPROVED PBI/6F POLYIMIDE BLENDS: THIRD GENERATION...PYROMELLITIC DIANHYDRIDE 100 A1.2 REVIEW AND RISK ANALYSIS 105 iv FIGURES FIGURE PAGE # I HIGH PERFORMANCE POLYMER BLENDS PLAN 6 2 PBI/ ULTEM SEPARATION

  15. Fabrication of keratin-silica hydrogel for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Kakkar, Prachi; Madhan, Balaraman, E-mail: bmadhan76@yahoo.co.in

    2016-09-01

    In the recent past, keratin has been fabricated into different forms of biomaterials like scaffold, gel, sponge, film etc. In lieu of the myriad advantages of the hydrogels for biomedical applications, a keratin-silica hydrogel was fabricated using tetraethyl orthosilicate (TEOS). Textural analysis shed light on the physical properties of the fabricated hydrogel, inturn enabling the optimization of the hydrogel. The optimized keratin-silica hydrogel was found to exhibit instant springiness, optimum hardness, with ease of spreadability. Moreover, the hydrogel showed excellent swelling with highly porous microarchitecture. MTT assay and DAPI staining revealed that keratin-silica hydrogel was biocompatible with fibroblast cells. Collectively, these properties make the fabricated keratin-silica hydrogel, a suitable dressing material for biomedical applications. - Highlights: • Keratin-silica hydrogel has been fabricated using sol–gel technique. • The hydrogel shows appropriate textural properties. • The hydrogel promotes fibroblast cells proliferation. • The hydrogel has potential soft tissue engineering applications like wound healing.

  16. Heparin release from thermosensitive hydrogels

    NARCIS (Netherlands)

    Gutowska, Anna; Bae, You Han; Feijen, Jan; Kim, Sung Wan

    1992-01-01

    Thermosensitive hydrogels (TSH) were synthesized and investigated as heparin releasing polymers for the prevention of surface induced thrombosis. TSH were synthesized with N-isopropyl acrylamide (NiPAAm) copolymerized with butyl methacrylate (BMA) (hydrophobic) or acrylic acid (AAc) (hydrophilic) co

  17. Polyvinyl alcohol hydrogels for iontohporesis

    Science.gov (United States)

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

    2013-06-01

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

  18. Hydrogels for therapeutic cardiovascular angiogenesis.

    Science.gov (United States)

    Rufaihah, Abdul Jalil; Seliktar, Dror

    2016-01-15

    Acute myocardial infarction (MI) caused by ischemia is the most common cause of cardiac dysfunction. While growth factor or cell therapy is promising, the retention of bioactive agents in the highly vascularized myocardium is limited and prevents sustained activation needed for adequate cellular responses. Various types of biomaterials with different physical and chemical properties have been developed to improve the localized delivery of growth factor and/or cells for therapeutic angiogenesis in ischemic tissues. Hydrogels are particularly advantageous as carrier systems because they are structurally similar to the tissue extracellular matrix (ECM), they can be processed under relatively mild conditions and can be delivered in a minimally invasive manner. Moreover, hydrogels can be designed to degrade in a timely fashion that coincides with the angiogenic process. For these reasons, hydrogels have shown great potential as pro-angiogenic matrices. This paper reviews a few of the hydrogel systems currently being applied together with growth factor delivery and/or cell therapy to promote therapeutic angiogenesis in ischemic tissues, with emphasis on myocardial applications.

  19. Peptide hydrogelation triggered by enzymatic induced pH switch

    Science.gov (United States)

    Cheng, Wei; Li, Ying

    2016-07-01

    It remains challenging to develop methods that can precisely control the self-assembling kinetics and thermodynamics of peptide hydrogelators to achieve hydrogels with optimal properties. Here we report the hydrogelation of peptide hydrogelators by an enzymatically induced pH switch, which involves the combination of glucose oxidase and catalase with D-glucose as the substrate, in which both the gelation kinetics and thermodynamics can be controlled by the concentrations of D-glucose. This novel hydrogelation method could result in hydrogels with higher mechanical stability and lower hydrogelation concentrations. We further illustrate the application of this hydrogelation method to differentiate different D-glucose levels.

  20. An amidated carboxymethylcellulose hydrogel for cartilage regeneration.

    Science.gov (United States)

    Leone, Gemma; Fini, Milena; Torricelli, Paola; Giardino, Roberto; Barbucci, Rolando

    2008-08-01

    An amidic derivative of carboxymethylcellulose was synthesized (CMCA). The new polysaccharide was obtained by converting a large percentage of carboxylic groups ( approximately 50%) of carboxymethylcellulose into amidic groups rendering the macromolecule quite similar to hyaluronan. Then, the polysaccharide (CMCA) was crosslinked. The behavior of CMCA hydrogel towards normal human articular chondrocytes (NHAC) was in vitro studied monitoring the cell proliferation and synthesis of extra cellular matrix (ECM) components and compared with a hyaluronan based hydrogel (Hyal). An extracellular matrix rich in cartilage-specific collagen and proteoglycans was secreted in the presence of hydrogels. The injectability of the new hydrogels was also analysed. An experimental in vivo model was realized to study the effect of CMCA and Hyal hydrogels in the treatment of surgically created partial thickness chondral defects in the rabbit knee. The preliminary results pointed out that CMCA hydrogel could be considered as a potential compound for cartilage regeneration.

  1. Hydrogels for Engineering of Perfusable Vascular Networks.

    Science.gov (United States)

    Liu, Juan; Zheng, Huaiyuan; Poh, Patrina S P; Machens, Hans-Günther; Schilling, Arndt F

    2015-07-14

    Hydrogels are commonly used biomaterials for tissue engineering. With their high-water content, good biocompatibility and biodegradability they resemble the natural extracellular environment and have been widely used as scaffolds for 3D cell culture and studies of cell biology. The possible size of such hydrogel constructs with embedded cells is limited by the cellular demand for oxygen and nutrients. For the fabrication of large and complex tissue constructs, vascular structures become necessary within the hydrogels to supply the encapsulated cells. In this review, we discuss the types of hydrogels that are currently used for the fabrication of constructs with embedded vascular networks, the key properties of hydrogels needed for this purpose and current techniques to engineer perfusable vascular structures into these hydrogels. We then discuss directions for future research aimed at engineering of vascularized tissue for implantation.

  2. Structure of Pigment Yellow 181 dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate from XRPD plus DFT-D

    DEFF Research Database (Denmark)

    van de Streek, Jacco

    2015-01-01

    -pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom, was determined in three stages by a combination of simulated annealing, partial Rietveld refinement with dummy atoms replacing the solvent molecules and further simulated annealing. The phase not being...

  3. Injectable, Biodegradable Hydrogels for Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Huaping Tan

    2010-03-01

    Full Text Available Hydrogels have many different applications in the field of regenerative medicine. Biodegradable, injectable hydrogels could be utilized as delivery systems, cell carriers, and scaffolds for tissue engineering. Injectable hydrogels are an appealing scaffold because they are structurally similar to the extracellular matrix of many tissues, can often be processed under relatively mild conditions, and may be delivered in a minimally invasive manner. This review will discuss recent advances in the field of injectable hydrogels, including both synthetic and native polymeric materials, which can be potentially used in cartilage and soft tissue engineering applications.

  4. Photocrosslinkable Gelatin Hydrogel for Epidermal Tissue Engineering.

    Science.gov (United States)

    Zhao, Xin; Lang, Qi; Yildirimer, Lara; Lin, Zhi Yuan; Cui, Wenguo; Annabi, Nasim; Ng, Kee Woei; Dokmeci, Mehmet R; Ghaemmaghami, Amir M; Khademhosseini, Ali

    2016-01-01

    Natural hydrogels are promising scaffolds to engineer epidermis. Currently, natural hydrogels used to support epidermal regeneration are mainly collagen- or gelatin-based, which mimic the natural dermal extracellular matrix but often suffer from insufficient and uncontrollable mechanical and degradation properties. In this study, a photocrosslinkable gelatin (i.e., gelatin methacrylamide (GelMA)) with tunable mechanical, degradation, and biological properties is used to engineer the epidermis for skin tissue engineering applications. The results reveal that the mechanical and degradation properties of the developed hydrogels can be readily modified by varying the hydrogel concentration, with elastic and compressive moduli tuned from a few kPa to a few hundred kPa, and the degradation times varied from a few days to several months. Additionally, hydrogels of all concentrations displayed excellent cell viability (>90%) with increasing cell adhesion and proliferation corresponding to increases in hydrogel concentrations. Furthermore, the hydrogels are found to support keratinocyte growth, differentiation, and stratification into a reconstructed multilayered epidermis with adequate barrier functions. The robust and tunable properties of GelMA hydrogels suggest that the keratinocyte laden hydrogels can be used as epidermal substitutes, wound dressings, or substrates to construct various in vitro skin models.

  5. Multi-model blending

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, Hendrik F.; Hwang, Youngdeok; van Kessel, Theodore G.; Khabibrakhmanov, Ildar K.; Muralidhar, Ramachandran

    2016-10-18

    A method and a system to perform multi-model blending are described. The method includes obtaining one or more sets of predictions of historical conditions, the historical conditions corresponding with a time T that is historical in reference to current time, and the one or more sets of predictions of the historical conditions being output by one or more models. The method also includes obtaining actual historical conditions, the actual historical conditions being measured conditions at the time T, assembling a training data set including designating the two or more set of predictions of historical conditions as predictor variables and the actual historical conditions as response variables, and training a machine learning algorithm based on the training data set. The method further includes obtaining a blended model based on the machine learning algorithm.

  6. Blended learning in anatomy

    DEFF Research Database (Denmark)

    Østergaard, Gert Værge; Brogner, Heidi Marie

    2016-01-01

    behind DBR is that new knowledge is generated through processes that simultaneously develop, test and improve a design, in this case, an educational design (1) The main principles used in the project is blended learning and flipped learning (2). …"I definitely learn best in practice, but the theory...... in working with the assignments in the classroom."... External assesor, observer and interviewer Based on the different evaluations, the conclusion are that the blended learning approach combined with the ‘flipped classroom’ is a very good way to learn and apply the anatomy, both for the students......The aim of the project was to bridge the gap between theory and practice by working more collaboratively, both peer-to-peer and between student and lecturer. Furthermore the aim was to create active learning environments. The methodology of the project is Design-Based Research (DBR). The idea...

  7. Bundle Formation in Biomimetic Hydrogels.

    Science.gov (United States)

    Jaspers, Maarten; Pape, A C H; Voets, Ilja K; Rowan, Alan E; Portale, Giuseppe; Kouwer, Paul H J

    2016-08-08

    Bundling of single polymer chains is a crucial process in the formation of biopolymer network gels that make up the extracellular matrix and the cytoskeleton. This bundled architecture leads to gels with distinctive properties, including a large-pore-size gel formation at very low concentrations and mechanical responsiveness through nonlinear mechanics, properties that are rarely observed in synthetic hydrogels. Using small-angle X-ray scattering (SAXS), we study the bundle formation and hydrogelation process of polyisocyanide gels, a synthetic material that uniquely mimics the structure and mechanics of biogels. We show how the structure of the material changes at the (thermally induced) gelation point and how factors such as concentration and polymer length determine the architecture, and with that, the mechanical properties. The correlation of the gel mechanics and the structural parameters obtained from SAXS experiments is essential in the design of future (synthetic) mimics of biopolymer networks.

  8. Fewer Bacteria Adhere to Softer Hydrogels

    Science.gov (United States)

    Kolewe, Kristopher W.; Peyton, Shelly R.; Schiffman, Jessica D.

    2015-01-01

    Clinically, biofilm-associated infections commonly form on intravascular catheters and other hydrogel surfaces. The overuse of antibiotics to treat these infections has led to the spread of antibiotic resistance and underscores the importance of developing alternative strategies that delay the onset of biofilm formation. Previously, it has been reported that during surface contact, bacteria can detect surfaces through subtle changes in the function of their motors. However, how the stiffness of a polymer hydrogel influences the initial attachment of bacteria is unknown. Systematically, we investigated poly(ethylene glycol) dimethacrylate (PEGDMA) and agar hydrogels that were twenty times thicker than the cumulative size of bacterial cell appendages, as a function of Young’s moduli. Soft (44.05 – 308.5 kPa), intermediate (1495 – 2877 kPa), and stiff (5152 – 6489 kPa) hydrogels were synthesized. Escherichia coli and Staphylococcus aureus attachment onto the hydrogels was analyzed using confocal microscopy after 2 and 24 hr incubation periods. Independent of hydrogel chemistry and incubation time, E. coli and S. aureus attachment correlated positively to increasing hydrogel stiffness. For example, after a 24 hr incubation period, there were 52% and 82% less E. coli adhered to soft PEGDMA hydrogels, than to the intermediate and stiff PEGDMA hydrogels, respectively. A 62% and 79% reduction in the area coverage by the Gram-positive microbe S. aureus occurred after 24 hr incubation on the soft versus intermediate and stiff PEGDMA hydrogels. We suggest that hydrogel stiffness is an easily tunable variable that, potentially, could be used synergistically with traditional antimicrobial strategies to reduce early bacterial adhesion, and therefore the occurrence of biofilm-associated infections. PMID:26291308

  9. Fewer Bacteria Adhere to Softer Hydrogels.

    Science.gov (United States)

    Kolewe, Kristopher W; Peyton, Shelly R; Schiffman, Jessica D

    2015-09-01

    Clinically, biofilm-associated infections commonly form on intravascular catheters and other hydrogel surfaces. The overuse of antibiotics to treat these infections has led to the spread of antibiotic resistance and underscores the importance of developing alternative strategies that delay the onset of biofilm formation. Previously, it has been reported that during surface contact, bacteria can detect surfaces through subtle changes in the function of their motors. However, how the stiffness of a polymer hydrogel influences the initial attachment of bacteria is unknown. Systematically, we investigated poly(ethylene glycol) dimethacrylate (PEGDMA) and agar hydrogels that were 20 times thicker than the cumulative size of bacterial cell appendages, as a function of Young's moduli. Soft (44.05-308.5 kPa), intermediate (1495-2877 kPa), and stiff (5152-6489 kPa) hydrogels were synthesized. Escherichia coli and Staphylococcus aureus attachment onto the hydrogels was analyzed using confocal microscopy after 2 and 24 h incubation periods. Independent of hydrogel chemistry and incubation time, E. coli and S. aureus attachment correlated positively to increasing hydrogel stiffness. For example, after a 24 h incubation period, there were 52 and 82% fewer E. coli adhered to soft PEGDMA hydrogels than to the intermediate and stiff PEGDMA hydrogels, respectively. A 62 and 79% reduction in the area coverage by the Gram-positive microbe S. aureus occurred after 24 h incubation on the soft versus intermediate and stiff PEGDMA hydrogels. We suggest that hydrogel stiffness is an easily tunable variable that could potentially be used synergistically with traditional antimicrobial strategies to reduce early bacterial adhesion and therefore the occurrence of biofilm-associated infections.

  10. Blending Canal Surfaces Based on PH Curves

    Institute of Scientific and Technical Information of China (English)

    Chen-Dong Xu; Fa-Lai Chen

    2005-01-01

    In this paper, a new method for blending two canal surfaces is proposed. The blending surface is itself a generalized canal surface, the spine curve of which is a PH (Pythagorean-Hodograph) curve. The blending surface possesses an attractive property - its representation is rational. The method is extensible to blend general surfaces as long as the blending boundaries are well-defined.

  11. Bioprinting of 3D hydrogels.

    Science.gov (United States)

    Stanton, M M; Samitier, J; Sánchez, S

    2015-08-07

    Three-dimensional (3D) bioprinting has recently emerged as an extension of 3D material printing, by using biocompatible or cellular components to build structures in an additive, layer-by-layer methodology for encapsulation and culture of cells. These 3D systems allow for cell culture in a suspension for formation of highly organized tissue or controlled spatial orientation of cell environments. The in vitro 3D cellular environments simulate the complexity of an in vivo environment and natural extracellular matrices (ECM). This paper will focus on bioprinting utilizing hydrogels as 3D scaffolds. Hydrogels are advantageous for cell culture as they are highly permeable to cell culture media, nutrients, and waste products generated during metabolic cell processes. They have the ability to be fabricated in customized shapes with various material properties with dimensions at the micron scale. 3D hydrogels are a reliable method for biocompatible 3D printing and have applications in tissue engineering, drug screening, and organ on a chip models.

  12. Evaluation of Photocrosslinked Lutrol Hydrogel for Tissue Printing Applications

    NARCIS (Netherlands)

    Fedorovich, Natalja E.; Swennen, Ives; Girones, Jordi; Moroni, Lorenzo; Blitterswijk, van Clemens A.; Schacht, Etienne; Alblas, Jacqueline; Dhert, Wouter J.A.

    2009-01-01

    Application of hydrogels in tissue engineering and innovative strategies such as organ printing, which is based on layered 3D deposition of cell-laden hydrogels, requires design of novel hydrogel matrices. Hydrogel demands for 3D printing include: 1) preservation of the printed shape after the depos

  13. Rapid Self-Integrating, Injectable Hydrogel for Tissue Complex Regeneration.

    Science.gov (United States)

    Hou, Sen; Wang, Xuefei; Park, Sean; Jin, Xiaobing; Ma, Peter X

    2015-07-15

    A novel rapid self-integrating, injectable, and bioerodible hydrogel is developed for bone-cartilage tissue complex regeneration. The hydrogels are able to self-integrate to form various structures, as can be seen after dying some hydrogel disks pink with rodamine. This hydrogel is demonstrated to engineer cartilage-bone complex.

  14. Evaluation of Photocrosslinked Lutrol Hydrogel for Tissue Printing applications

    NARCIS (Netherlands)

    Fedorovich, Natalja E.; Swennen, Ives; Girones, Jordi; Moroni, Lorenzo; van Blitterswijk, Clemens; Schacht, Etienne; Alblas, Jacqueline; Dhert, Wouter J.A.

    2009-01-01

    Application of hydrogels in tissue engineering and innovative strategies such as organ printing, which is based on layered 3D deposition of cell-laden hydrogels, requires design of novel hydrogel matrices. Hydrogel demands for 3D printing include: 1) preservation of the printed shape after the

  15. Switchable antimicrobial and antifouling hydrogels with enhanced mechanical properties.

    Science.gov (United States)

    Cao, Bin; Tang, Qiong; Li, Linlin; Humble, Jayson; Wu, Haiyan; Liu, Lingyun; Cheng, Gang

    2013-08-01

    New switchable hydrogels are developed. Under acidic conditions, hydrogels undergo self-cyclization and can catch and kill bacteria. Under neutral/basic conditions, hydrogels undergo ring-opening and can release killed bacterial cells and resist protein adsorption and bacterial attachment. Smart hydrogels also show a dramatically improved mechanical property, which is highly desired for biomedical applications.

  16. Blended Learning in English Literature

    OpenAIRE

    Haugestad, Astrid

    2015-01-01

    Abstract Blended Learning This study investigates blended learning used in a course of English Literature and Culture in upper secondary school. It raises the question how the use of blended learning may promote and encourage learning in a course of English literature and culture. The study also compares traditional face-to-face classroom communication with communication mediated by digital artefacts. It has been important to go beyond the strictly technical issues ...

  17. 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.

  18. Hydrogels with Micellar Hydrophobic (Nano)Domains

    OpenAIRE

    Pekař, Miloslav

    2015-01-01

    Hydrogels containing hydrophobic domains or nanodomains, especially of the micellar type, are reviewed. Examples of the reasons for introducing hydrophobic domains into hydrophilic gels are given; typology of these materials is introduced. Synthesis routes are exemplified and properties of a variety of such hydrogels in relation with their intended applications are described. Future research needs are identified briefly.

  19. Hydrogels with micellar hydrophobic (nano)domains

    OpenAIRE

    Miloslav ePekař

    2015-01-01

    Hydrogels containing hydrophobic domains or nanodomains, especially of the micellar type, are reviewed. Examples of the reasons for introducing hydrophobic domains into hydrophilic gels are given; typology of these materials is introduced. Synthesis routes are exemplified and properties of a variety of such hydrogels in relation with their intended applications are described. Future research needs are identified briefly.

  20. 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.

  1. Impermeable Robust Hydrogels via Hybrid Lamination.

    Science.gov (United States)

    Parada, German A; Yuk, Hyunwoo; Liu, Xinyue; Hsieh, Alex J; Zhao, Xuanhe

    2017-07-17

    Hydrogels have been proposed for sensing, drug delivery, and soft robotics applications, yet most of these materials suffer from low mechanical robustness and high permeability to small molecules, limiting their widespread use. This study reports a general strategy and versatile method to fabricate robust, highly stretchable, and impermeable hydrogel laminates via hybrid lamination of an elastomer layer bonded between hydrogel layers. By controlling the layers' composition and thickness, it is possible to tune the stiffness of the impermeable hydrogels without sacrificing the stretchability. These hydrogel laminates exhibit ultralow surface coefficients of friction and, unlike common single-material hydrogels, do not allow diffusion of various molecules across the structure due to the presence of the elastomer layer. This feature is then used to release different model drugs and, in a subsequent experiment, to sense different pH conditions on the two sides of the hydrogel laminate. A potential healthcare application is shown using the presented method to coat medical devices (catheter, tubing, and condom) with hydrogel, to allow for drug release and sensing of environmental conditions for gastrointestinal or urinary tract. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Photopatterning of hydrogel microarryas in closed microchips

    NARCIS (Netherlands)

    Gümüscü, B.; Bomer, Johan G.; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    To date, optical lithography has been extensively used for in situ patterning of hydrogel structures in a scale range from hundreds of microns to a few millimeters. The two main limitations which prevent smaller feature sizes of hydrogel structures are (1) the upper glass layer of a microchip

  3. Hydrogels with micellar hydrophobic (nano)domains

    Science.gov (United States)

    Pekař, Miloslav

    2014-12-01

    Hydrogels containing hydrophobic domains or nanodomains, especially of the micellar type, are reviewed. Examples of the reasons for introducing hydrophobic domains into hydrophilic gels are given; typology of these materials is introduced. Synthesis routes are exemplified and properties of a variety of such hydrogels in relation with their intended applications are described. Future research needs are identified briefly.

  4. Photopatterning of hydrogel microarryas in closed microchips

    NARCIS (Netherlands)

    Gumuscu, Burcu; Bomer, Johan G.; Berg, van den Albert; Eijkel, Jan C.T.

    2015-01-01

    To date, optical lithography has been extensively used for in situ patterning of hydrogel structures in a scale range from hundreds of microns to a few millimeters. The two main limitations which prevent smaller feature sizes of hydrogel structures are (1) the upper glass layer of a microchip mainta

  5. Design of Hydrogels for Biomedical Applications.

    Science.gov (United States)

    Kamata, Hiroyuki; Li, Xiang; Chung, Ung-Il; Sakai, Takamasa

    2015-11-18

    Hydrogels are considered key tools for the design of biomaterials, such as wound dressings, drug reservoirs, and temporary scaffolds for cells. Despite their potential, conventional hydrogels have limited applicability under wet physiological conditions because they suffer from the uncontrollable temporal change in shape: swelling takes place immediately after the installation. Swollen hydrogels easily fail under mechanical stress. The morphological change may cause not only the slippage from the installation site but also local nerve compression. The design of hydrogels that can retain their original shape and mechanical properties in an aqueous environment is, therefore, of great importance. On the one hand, the controlled degradation of used hydrogels has to be realized in some biomedical applications. This Progress Report provides a brief overview of the recent progress in the development of hydrogels for biomedical applications. Practical approaches to control the swelling properties of hydrogels are discussed. The designs of hydrogels with controlled degradation properties as well as the theoretical models to predict the degradation behavior are also introduced. Moreover, current challenges and limitation toward biomedical applications are discussed, and future directions are offered.

  6. Soy-based Hydrogels for Biomedical Applications

    Science.gov (United States)

    Soy based hydrogels were prepared by ring-opening polymerization of epoxidized soybean oil, following hydrolysis of formed polymers. The hydrogels were evaluated loading and releasing water-soluble anticancer drug doxorubin (Dox). The results suggest that this new system offers a great potential t...

  7. Blended-Learning-Projekte im Unternehmen

    OpenAIRE

    Keller, Miriam; Back, Andrea

    2004-01-01

    Der Arbeitsbericht Blended-Learning-Projekte im Unternehmen liefert einen Beitrag zur Bearbeitung des Themas Blended Learning und liefert dem Leser einen Überblick und erste Anregungen zur Planung, Integration und Gestaltung von Blended-Learning-Konzepten im Unternehmen.

  8. Whey protein aerogel as blended with cellulose crystalline particles or loaded with fish oil.

    Science.gov (United States)

    Ahmadi, Maede; Madadlou, Ashkan; Saboury, Ali Akbar

    2016-04-01

    Whey protein hydrogels blended with nanocrystalline and microcrystalline cellulose particles (NCC and MCC, respectively) were prepared, followed by freeze-drying, to produce aerogels. NCC blending increased the Young's modulus, and elastic character, of the protein aerogel. Aerogels were microporous and mesoporous materials, as characterized by the pores sizing 1.2 nm and 12.2 nm, respectively. Blending with NCC decreased the count of both microporous and mesoporous-classified pores at the sub-100 nm pore size range investigated. In contrast, MCC blending augmented the specific surface area and pores volume of the aerogel. It also increased moisture sorption affinity of aerogel. The feasibility of conveying hydrophobic nutraceuticals by aerogels was evaluated through loading fish oil into the non-blended aerogel. Oil loading altered its microstructure, corresponding to a peak displacement in Fourier-transform infra-red spectra, which was ascribed to increased hydrophobic interactions. Surface coating of aerogel with zein decreased the oxidation susceptibility of the loaded oil during subsequent storage.

  9. Cellulose/polyvinyl alcohol-based hydrogels for reconfigurable lens

    Science.gov (United States)

    Jayaramudu, T.; Ko, Hyun-U.; Gao, Xiaoyuan; Li, Yaguang; Kim, Sang Youn; Kim, Jaehwan

    2016-04-01

    Electroactive hydrogels are attractive for soft robotics and reconfigurable lens applications. Here we describe the design and fabrication of cellulose-poly vinyl alcohol based hydrogels. The fabricated hydrogels were confirmed by Fourier transformer spectroscopy, swelling studies, thermal analysis, surface morphology of fabricated hydrogel was study by using scanning electron microscopy. The effect of poly vinyl alcohol concentration on the optical and electrical behavior of hydrogels was studied.

  10. 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.

  11. Managing as blended care.

    Science.gov (United States)

    Mintzberg, H

    1994-09-01

    As part of a research project on managerial work based on a new model of the roles, the head nurse of a hospital unit was observed during a working day. Her work is described, with reference especially to the roles of leading, linking, controlling, and doing. Conclusions are drawn about the advantages of a craft style of management as opposed to the more traditional "boss" or professional styles. The author also discusses what those in general management can learn from those in nursing management, which seems best practiced out in the open, on one's feet, as a kind of blended care.

  12. Blended Learning on Campus

    DEFF Research Database (Denmark)

    Heilesen, Simon; Nielsen, Jørgen Lerche

    2004-01-01

    On the basis of a large-scale project implementing information and communication technology at Roskilde University, Denmark, this paper discusses ways of introducing technology-based blended learning in academic life. We examine some examples of use of systems for computer-mediated collabora......-tive learning and work in Danish Open University education as well as in courses on campus. We further suggest some possi-bilities for using technology in innovative ways, arguing that innovation is to be found, not in isolated instantiations of sys-tems, but in the form of a deliberate integration of all...... relevant ICT-features as a whole into the learning environment....

  13. Short fiber reinforced thermoplastic blends

    NARCIS (Netherlands)

    Malchev, P.G.

    2008-01-01

    The present thesis investigates the potential of short fiber reinforced thermoplastic blends, a combination of an immiscible polymer blend and a short fiber reinforced composite, to integrate the easy processing solutions available for short fiber reinforced composites with the high mechanical perfo

  14. The Basics of Blended Instruction

    Science.gov (United States)

    Tucker, Catlin R.

    2013-01-01

    Even though many of teachers do not have technology-rich classrooms, the rapidly evolving education landscape increasingly requires them to incorporate technology to customize student learning. Blended learning, with its mix of technology and traditional face-to-face instruction, is a great approach. Blended learning combines classroom learning…

  15. Blended Learning: An Innovative Approach

    Science.gov (United States)

    Lalima; Dangwal, Kiran Lata

    2017-01-01

    Blended learning is an innovative concept that embraces the advantages of both traditional teaching in the classroom and ICT supported learning including both offline learning and online learning. It has scope for collaborative learning; constructive learning and computer assisted learning (CAI). Blended learning needs rigorous efforts, right…

  16. Blended Learning: A Dangerous Idea?

    Science.gov (United States)

    Moskal, Patsy; Dziuban, Charles; Hartman, Joel

    2013-01-01

    The authors make the case that implementation of a successful blended learning program requires alignment of institutional, faculty, and student goals. Reliable and robust infrastructure must be in place to support students and faculty. Continuous evaluation can effectively track the impact of blended learning on students, faculty, and the…

  17. Classifying K-12 Blended Learning

    Science.gov (United States)

    Staker, Heather; Horn, Michael B.

    2012-01-01

    The growth of online learning in the K-12 sector is occurring both remotely through virtual schools and on campuses through blended learning. In emerging fields, definitions are important because they create a shared language that enables people to talk about the new phenomena. The blended-learning taxonomy and definitions presented in this paper…

  18. Short fiber reinforced thermoplastic blends

    NARCIS (Netherlands)

    Malchev, P.G.

    2008-01-01

    The present thesis investigates the potential of short fiber reinforced thermoplastic blends, a combination of an immiscible polymer blend and a short fiber reinforced composite, to integrate the easy processing solutions available for short fiber reinforced composites with the high mechanical perfo

  19. Blended Learning: A Dangerous Idea?

    Science.gov (United States)

    Moskal, Patsy; Dziuban, Charles; Hartman, Joel

    2013-01-01

    The authors make the case that implementation of a successful blended learning program requires alignment of institutional, faculty, and student goals. Reliable and robust infrastructure must be in place to support students and faculty. Continuous evaluation can effectively track the impact of blended learning on students, faculty, and the…

  20. Survey design for blended acquisition

    NARCIS (Netherlands)

    Blacquière, G.; Berkhout, A.J.; Verschuur, D.J.

    2009-01-01

    When designing an acquisition geometry for the case of source blending, it is important that the blended source arrays are capable of transmitting a wavefield with a large spatial and temporal bandwidth: the wavefield must be incoherent. We call this incoherent shooting. Furthermore, the array must

  1. Blended Learning Improves Science Education.

    Science.gov (United States)

    Stockwell, Brent R; Stockwell, Melissa S; Cennamo, Michael; Jiang, Elise

    2015-08-27

    Blended learning is an emerging paradigm for science education but has not been rigorously assessed. We performed a randomized controlled trial of blended learning. We found that in-class problem solving improved exam performance, and video assignments increased attendance and satisfaction. This validates a new model for science communication and education.

  2. Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) elastomer via UV-induced graft polymerization of N-vinyl pyrrolidone.

    Science.gov (United States)

    Luan, Shifang; Zhao, Jie; Yang, Huawei; Shi, Hengchong; Jin, Jing; Li, Xiaomeng; Liu, Jingchuan; Wang, Jianwei; Yin, Jinghua; Stagnaro, Paola

    2012-05-01

    Poly(N-vinyl pyrrolidone) (PNVP) was covalently grafted onto the surface of biomedical poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer via a technique of UV-induced graft polymerization combined with plasma pre-treatment. The surface graft polymerization of N-vinyl pyrrolidone (NVP) was confirmed by ATR-FTIR and XPS. Effect of the parameters of graft polymerization, i.e., the initiator concentration, the UV irradiation time and the monomer concentration on the grafting density was investigated. The morphology and the wettability of the PNVP-modified surfaces were characterized by AFM and DSA, respectively. Protein adsorption and platelet adhesion were obviously suppressed after PNVP was grafted onto the SEBS substrates.

  3. Orthogonal Enzymatic Reactions to Control Supramolecular Hydrogelations%Orthogonal Enzymatic Reactions to Control Supramolecular Hydrogelations

    Institute of Scientific and Technical Information of China (English)

    陈国钦; 任春华; 王玲; 徐兵; 杨志谋

    2012-01-01

    Enzyme-responsive hydrogels have great potential in applications of controlled drug release, tissue engineering, etc. In this study, we reported on a supramolecular hydrogel that showed responses to two enzymes, phosphatase which was used to form the hydrogels and esterase which could trigger gelsol phase transitions. The gelation process and visco-elasticity property of the resulting gel, morphology of the nanostructures in hydrogel, and peptide conformation in the self-assembled nanostructure were characterized by theology, transmission electron microscope (TEM), and circular dichroism (CD), respectively. Potential application of the enzyme-responsive hydrogel in drug release was also demonstrated in this study. Though only one potential application of drug release was proved in this study, the responsive hydrogel system in this study might have potentials for the applications in fields of cell culture, controlled-drug release, etc.

  4. Injectable glycosaminoglycan-protein nano-complex in semi-interpenetrating networks: A biphasic hydrogel for hyaline cartilage regeneration.

    Science.gov (United States)

    Radhakrishnan, Janani; Subramanian, Anuradha; Sethuraman, Swaminathan

    2017-11-01

    Articular hyaline cartilage regeneration remains challenging due to its less intrinsic reparability. The study develops injectable biphasic semi-interpenetrating polymer networks (SIPN) hydrogel impregnated with chondroitin sulfate (ChS) nanoparticles for functional cartilage restoration. ChS loaded zein nanoparticles (∼150nm) prepared by polyelectrolyte-protein complexation were interspersed into injectable SIPNs developed by blending alginate with poly(vinyl alcohol) and calcium crosslinking. The hydrogel exhibited interconnected porous microstructure (39.9±5.8μm pore diameter, 57.7±5.9% porosity), 92% swellability and >350Pa elastic modulus. Primary chondrocytes compatibility, chondrocyte-matrix interaction with cell-cell clustering and spheroidal morphology was demonstrated in ChS loaded hydrogel and long-term (42days) proliferation was also determined. Higher fold expression of cartilage-specific genes sox9, aggrecan and collagen-II was observed in ChS loaded hydrogel while exhibiting poor expression of collagen-I. Immunoblotting of aggregan and collagen II demonstrate favorable positive influence of ChS on chondrocytes. Thus, the injectable biphasic SIPNs could be promising composition-mimetic substitute for cartilage restoration at irregular defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Designing hydrogels for controlled drug delivery

    Science.gov (United States)

    Li, Jianyu; Mooney, David J.

    2016-12-01

    Hydrogel delivery systems can leverage therapeutically beneficial outcomes of drug delivery and have found clinical use. Hydrogels can provide spatial and temporal control over the release of various therapeutic agents, including small-molecule drugs, macromolecular drugs and cells. Owing to their tunable physical properties, controllable degradability and capability to protect labile drugs from degradation, hydrogels serve as a platform on which various physiochemical interactions with the encapsulated drugs occur to control drug release. In this Review, we cover multiscale mechanisms underlying the design of hydrogel drug delivery systems, focusing on physical and chemical properties of the hydrogel network and the hydrogel-drug interactions across the network, mesh and molecular (or atomistic) scales. We discuss how different mechanisms interact and can be integrated to exert fine control in time and space over drug presentation. We also collect experimental release data from the literature, review clinical translation to date of these systems and present quantitative comparisons between different systems to provide guidelines for the rational design of hydrogel delivery systems.

  6. RF-interrogatable hydrogel-actuated biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Hoel, Z; Wang, A W; Darrow, C B; Lee, A P; McConaghy, C F; Krulevitch, P; Gilman, A; Satcher, J H; Lane, S M

    2000-01-10

    The authors present a novel micromachined sensor that couples a swellable hydrogel with capacitive detection. The hydrogel swells in response to analyte concentration, exerting contact pressure on a deformable conducting membrane. Results are presented for characterization of a PHEMA hydrogel swelling in response to a calcium nitrate solution. Pressure-deflection measurements are performed on NiTi-based membranes. Hydrogel-actuated deflections of the membranes are measured. These measurements are correlated to determine the pressure generating characteristics of the hydrogel. Membrane deflection techniques have not previously been employed for hydrogel characterization. The PHEMA sample exhibited greatest sensitivity in the pH range of 6.0--6.5 and performed an average of 2.8 Joules of work per m{sup 3} per pH unit in response to ambient conditions over the pH range 3.5--6.5. The membrane deflections correspond to capacitive shifts of about 4 pF per pH unit for a capacitive transducer with initial gap of 100 {micro}m, capacitor plate area of 18.5 mm{sup 2} , and initial hydrogel volume of 11 {micro}L.

  7. Blend or not to blend: a study investigating faculty members perceptions of blended teaching

    Directory of Open Access Journals (Sweden)

    Mehmet A Ocak

    2010-12-01

    Full Text Available This study examined faculty members’ perceptions of blended teaching from several perspectives. A total of 73 faculty members in Turkish Higher Education context participated in the study by completing an online survey that combined quantitative and qualitative approaches. Based on a data analysis, the faculty members’ perceptions were sorted into six categories: (a satisfaction with blended teaching, (b perceived impact on the role of the faculty, (c perceived impact on student learning, (d perceived impact on student motivation, (e advantages of blended teaching, and (f disadvantages of blended teaching. Findings indicated that faculty members were likely to agree that blended teaching provides a high degree of satisfaction and that it requires more time and commitment from the faculty. The faculty members perceived that blended teaching improves student learning and, to some extent, improves motivation. The faculty members also emphasized the importance of institutional support and the use of technology to mitigate student problems. This study presents these faculty members’ perceptions, which are helpful for those planning to implement a blended teaching approach, and makes suggestions for trouble-shooting and taking advantage of the opportunities in a blended environment successfully.

  8. Photopatterning of Hydrogel Microarrays in Closed Microchips.

    Science.gov (United States)

    Gumuscu, Burcu; Bomer, Johan G; van den Berg, Albert; Eijkel, Jan C T

    2015-12-14

    To date, optical lithography has been extensively used for in situ patterning of hydrogel structures in a scale range from hundreds of microns to a few millimeters. The two main limitations which prevent smaller feature sizes of hydrogel structures are (1) the upper glass layer of a microchip maintains a large spacing (typically 525 μm) between the photomask and hydrogel precursor, leading to diffraction of UV light at the edges of mask patterns, (2) diffusion of free radicals and monomers results in irregular polymerization near the illumination interface. In this work, we present a simple approach to enable the use of optical lithography to fabricate hydrogel arrays with a minimum feature size of 4 μm inside closed microchips. To achieve this, we combined two different techniques. First, the upper glass layer of the microchip was thinned by mechanical polishing to reduce the spacing between the photomask and hydrogel precursor, and thereby the diffraction of UV light at the edges of mask patterns. The polishing process reduces the upper layer thickness from ∼525 to ∼100 μm, and the mean surface roughness from 20 to 3 nm. Second, we developed an intermittent illumination technique consisting of short illumination periods followed by relatively longer dark periods, which decrease the diffusion of monomers. Combination of these two methods allows for fabrication of 0.4 × 10(6) sub-10 μm sized hydrogel patterns over large areas (cm(2)) with high reproducibility (∼98.5% patterning success). The patterning method is tested with two different types of photopolymerizing hydrogels: polyacrylamide and polyethylene glycol diacrylate. This method enables in situ fabrication of well-defined hydrogel patterns and presents a simple approach to fabricate 3-D hydrogel matrices for biomolecule separation, biosensing, tissue engineering, and immobilized protein microarray applications.

  9. Synthesis of Poly(N-vinyl-2-pyrrolidone-co-methyl methacrylate by Maghnite-H+ a Non-toxic Catalyst

    Directory of Open Access Journals (Sweden)

    Mohamed Benadda

    2014-10-01

    Full Text Available In the present work poly (N-vinyl-2-pyrrolidone-co-methyl methacrylate copolymers were prepared successfully and cleanly by a one step process via cationic copolymerization of N-vinyl-2-pyrrolidone (NVP with methyl methacrylate (MMA, in heterogeneous phase using “Maghnite-H+” (Mag-H+ as catalyst in bulk, Maghnite is a montmorillonite sheet silicate clay exchanged with protons to produce Maghnite-H+. Temperature is varied between 20 and 80 °C. The effects of reaction temperature, amount of Mag-H+ on the yield and the intrinsic viscosity (η were investigated. A typical reaction product of poly (NVP-co- MMA was analyzed by infra red spectroscopy (FTIR and 1H-NMR, 13C-NMR spectroscopy as well as by viscosimetry. © 2014 BCREC UNDIP. All rights reservedReceived: 24th November 2013; Revised: 30th June 2014; Accepted: 8th July 2014How to Cite: Benadda, M., Ferrahi, M.I., Belbachir, M. (2014. Synthesis of Poly(N-vinyl-2-pyrrolidone-co-methyl methacrylate by Maghnite-H+ a Non-toxic Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 9 (3: 201-206. (doi: 10.9767/bcrec.9.3.5743.201-206Permalink/DOI: http://dx.doi.org/10.9767/bcrec.9.3.5743.201-206

  10. Effect of chitosan addition and gamma radiation on polymeric blends of PVP and PVAL; Efeito da adicao de quitosana e da radiacao gama em blendas polimericas de PVP e PVAL

    Energy Technology Data Exchange (ETDEWEB)

    Terence, M.C.; Castro, P.J.; Miranda, L.F.; Faldini, S.B., E-mail: mauroterence@yahoo.com.b [Universidade Presbiteriana Mackenzie, Sao Paulo. SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The objective of this project is the study of the effect of chitosan addition and the radiation with gamma rays. The polymeric blend usage is a recent development that expanded the applications of the polymers, due to the improvement of the properties of a single polymer. The PVP and PVAL were chosen because they present the main required characteristics to the formation of a hydrogel, such as water absorption and crosslinking, and the chitosan to improve the interaction between the hydrogel and the organism. The flexibility of the PVP was added with the mechanical resistance of the PVAL and the chitosan biocompatibility. With a defined concentration of PVP and PVAL, films of this blend was irradiated and also solutions with different concentrations of chitosan was prepared to obtain new films of this blend. After obtaining the films, some assays were realized to evaluate the mechanical properties. (author)

  11. The matrix reloaded: the evolution of regenerative hydrogels

    Directory of Open Access Journals (Sweden)

    Esmaiel Jabbari

    2016-05-01

    Full Text Available Cell-laden hydrogels can regenerate lost, damaged or malfunctioning tissues. Clinical success of such hydrogels is strongly dependent on the ability to tune their chemical, physico-mechanical, and biological properties to a specific application. In particular, mimicking the intricate arrangement of cell-interactive ligands of natural tissues is crucial to proper tissue function. Natural extracellular matrix elements represent a unique source for generating such interactions. A plethora of extracellular matrix-based approaches have been explored to augment the regenerative potential of hydrogels. These efforts include the development of matrix-like hydrogels, hydrogels containing matrix-like molecules, hydrogels containing decellularized matrix, hydrogels derived from decellularized matrix, and decellularized tissues as reimplantable matrix hydrogels. Here we review the evolution, strengths and weaknesses of these developments from the perspective of creating tissue regenerating hydrogels.

  12. Electrochemical Hydrogel Lithography of Calcium-Alginate Hydrogels for Cell Culture

    Directory of Open Access Journals (Sweden)

    Fumisato Ozawa

    2016-08-01

    Full Text Available Here we propose a novel electrochemical lithography methodology for fabricating calcium-alginate hydrogels having controlled shapes. We separated the chambers for Ca2+ production and gel formation with alginate with a semipermeable membrane. Ca2+ formed in the production chamber permeated through the membrane to fabricate a gel structure on the membrane in the gel formation chamber. When the calcium-alginate hydrogels were modified with collagen, HepG2 cells proliferated on the hydrogels. These results show that electrochemical hydrogel lithography is useful for cell culture.

  13. A review on polymeric hydrogel membranes for wound dressing applications: PVA-based hydrogel dressings

    Directory of Open Access Journals (Sweden)

    Elbadawy A. Kamoun

    2017-05-01

    Full Text Available This review presents the past and current efforts with a brief description on the featured properties of hydrogel membranes fabricated from biopolymers and synthetic ones for wound dressing applications. Many endeavors have been exerted during past ten years for developing new artificial polymeric membranes, which fulfill the demanded conditions for the treatment of skin wounds. This review mainly focuses on representing specifications of ideal polymeric wound dressing membranes, such as crosslinked hydrogels compatible with wound dressing purposes. But as the hydrogels with single component have low mechanical strength, recent trends have offered composite or hybrid hydrogel membranes to achieve the typical wound dressing requirements.

  14. High spatial frequency periodic structures induced on ferric ion-doped Polyvinyl Pyrrolidone film by femtosecond laser pulses

    CERN Document Server

    Lai, Chen; Wang, Yunxia; Li, Qiang; Wu, Lijun

    2016-01-01

    Utilizing continues-wave or pulsed laser to induce nano-structures on various material surfaces is one significant method in nano-fabrication technology. In this report, we investigate the formation of high spatial frequency periodic structures on Polyvinyl Pyrrolidone (PVP) film by a linearly polarized femtosecond laser. Ferric (Fe) ions are introduced into the film to improve the photosensitivity. Regular nano-gratings with spatial periods at the range of 60-100nm, which are about one tenth of the irradiating wavelength, can be induced. The period direction of the nano-gratings is perpendicular to the polarization of the femtosecond laser. By tuning the laser energy and scanning speed, we find that the nano-gratings can be formed in a wide range of experimental parameters. As high laser energy can excite not only metals, but also semiconductors and polymers, we believe the formation of the nano-gratings is due to the interaction between the incident femtosecond laser and surface plasmons. The laser processa...

  15. Putative relationship between hormonal status and serum pyrrolidone carboxypeptidase activity in pre- and post- menopausal women with breast cancer.

    Science.gov (United States)

    Carrera-González, María del Pilar; Ramírez-Expósito, María Jesús; Dueñas, Basilio; Martínez-Ferrol, Julia; Mayas, María Dolores; Martínez-Martos, José Manuel

    2012-12-01

    In breast cancer, hormonal changes are rather constant in post-menopausal women since they tend to vary only over long time spans. However, in pre-menopausal women, the development of breast cancer is associated with hormonal physiological variations. The aim of the present work was to analyse the changes in circulating levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in pre- and post-menopausal women that were healthy or with breast cancer, and their connection to serum pyrrolidone carboxypeptidase (Pcp) activity. We observed significant changes in the hormonal profile in post-menopausal women with breast cancer compared to the control group. In pre-menopausal women, we found significant changes in circulating GnRH levels with respect to the healthy group. Our present results support the existence of neuroendocrine misregulation that could be involved in tumour progression, with Pcp being a potentially new pharmacological target in breast cancer treatments.

  16. Fabrication of high quality carbonaceous coating on Cu nanoparticle using poly(vinyl pyrrolidone) and its application for oxidation prevention

    Science.gov (United States)

    Pyo, Youngjun; Choi, Dahyun; Son, Yeon-Ho; Kang, Suhee; Yoon, Eric H.; Jung, Seung-Boo; Kim, Yongil; Sunyong Lee, Caroline

    2016-05-01

    A novel method of carbonaceous coating on the surface of copper particles was developed through a chemical vapor deposition (CVD) process to prevent the oxidation of copper nanoparticles (CNPs). The types of poly(vinyl pyrrolidone) (PVP) used were K-12 (M W 3,500) and K-30 (M W 45,000). The amounts of PVP used ranged from 10 to 50 wt %. Additionally, processing temperatures of 900 and 875 °C were tested and compared. The optimum CVD process conditions for the carbonaceous coating were as follows: 875 °C processing temperature, 50 wt % K12 PVP solution, and gas conditions of \\text{Ar}:\\text{H}2 = 1:1. The resistivity change in the fabricated copper pattern was confirmed that the initial resistivity value of the ink with a mixing ratio of carbonaceous-coated CNPs to 1-octanethiol-coated CNPs of 4:6 (w/w) maintained its initial resistivity value of 2.93 × 10-7 Ω·m for more than 210 days.

  17. Prediction of protein modification sites of pyrrolidone carboxylic acid using mRMR feature selection and analysis.

    Directory of Open Access Journals (Sweden)

    Lu-Lu Zheng

    Full Text Available Pyrrolidone carboxylic acid (PCA is formed during a common post-translational modification (PTM of extracellular and multi-pass membrane proteins. In this study, we developed a new predictor to predict the modification sites of PCA based on maximum relevance minimum redundancy (mRMR and incremental feature selection (IFS. We incorporated 727 features that belonged to 7 kinds of protein properties to predict the modification sites, including sequence conservation, residual disorder, amino acid factor, secondary structure and solvent accessibility, gain/loss of amino acid during evolution, propensity of amino acid to be conserved at protein-protein interface and protein surface, and deviation of side chain carbon atom number. Among these 727 features, 244 features were selected by mRMR and IFS as the optimized features for the prediction, with which the prediction model achieved a maximum of MCC of 0.7812. Feature analysis showed that all feature types contributed to the modification process. Further site-specific feature analysis showed that the features derived from PCA's surrounding sites contributed more to the determination of PCA sites than other sites. The detailed feature analysis in this paper might provide important clues for understanding the mechanism of the PCA formation and guide relevant experimental validations.

  18. Preparation of Cellulosic Membrane Containing Pyrrolidone Moiety Via Radiation Induced Grafting and its Application in Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    A. S. Aly

    2005-01-01

    Full Text Available Radiation induced grafting of vinyl pyrrolidone onto cellulose wood pulp was carried out in heterogeneous and homogenous media using gamma radiation. Cellulose wood pulp was used in different forms; a in a homogenous solution by dissolving the wood pulp in N,N- dimethylacetamide/Lithium chloride (DMAc/LiCl mixture , b in a membrane form, by precipitating the cellulose solution in water and c in a powder form. Factors affecting on the grafting such as radiation dose, monomer concentration, precipitator concentration and thickness of the membrane have been studied. The result showed that at the same dose, the grafting yield was higher with cellulose in soluble form than in the membrane form, whereas cellulose in powder exhibited the lowest graft yield. The grafted membrane was characterized by IR, TGA and SEM. The ability of the grafted membrane to remove dyes (acid and basic dye, heavy metal ions (Co 2+ , Ni 2+ and Cu 2+ and phenols from wastewater was also reported.

  19. Ibogan, tacaman, and cytotoxic bisindole alkaloids from tabernaemontana. Cononusine, an iboga alkaloid with unusual incorporation of a pyrrolidone moiety.

    Science.gov (United States)

    Lim, Kuan-Hon; Raja, Vijay J; Bradshaw, Tracey D; Lim, Siew-Huah; Low, Yun-Yee; Kam, Toh-Seok

    2015-05-22

    Six new indole alkaloids, viz., cononusine (1, a rare example of an iboga-pyrrolidone conjugate), ervaluteine (2), vincamajicine (3), tacamonidine (4), 6-oxoibogaine (5), and N(4)-chloromethylnorfluorocurarine chloride (6), and two new vobasinyl-iboga bisindole alkaloids, ervatensines A (7) and B (8), in addition to other known alkaloids, were isolated from the stem-bark extract of the Malayan Tabernaemontana corymbosa. The structures of these alkaloids were established on the basis of NMR and MS analyses and, in one instance (7), confirmed by X-ray diffraction analysis. Vincamajicine (3) showed appreciable activity in reversing multidrug resistance in vincristine-resistant KB cells (IC50 2.62 μM), while ervatensines A (7) and B (8) and two other known bisindoles displayed pronounced in vitro growth inhibitory activity against human KB cells (IC50 < 2 μM). Compounds 7 and 8 also showed good growth inhibitory activity against A549, MCF-7, MDA-468, HCT-116, and HT-29 cells (IC50 0.70-4.19 μM). Cell cycle and annexin V-FITC apoptosis assays indicated that compounds 7 and 8 inhibited proliferation of HCT-116 and MDA-468 cells, evoking apoptotic and necrotic cell death.

  20. A Novel Research on Behavior of Zinc Ferrite Nanoparticles in Different Concentration of Poly(vinyl pyrrolidone (PVP

    Directory of Open Access Journals (Sweden)

    Halimah Mohamed Kamari

    2014-04-01

    Full Text Available Zinc ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various of concentrations of poly(vinyl pyrrolidone (PVP, i.e., 0, 15, 40, and 55 g/L, as a capping agent. To stabilize the particles, they were thermally treated at 873 K, as an optimum calcination temperature. The behaviors of the polymeric precursor were analyzed by use of simultaneous thermo-gravimetry (TG and derivative thermo-gravimetry analyses (DTG. The presence of the crystalline phase in each sample was confirmed by X-ray diffraction (XRD analysis. The average particle size and the morphology of the nanoparticles were determined by transmission electron microscopy (TEM, and these parameters were found to differ at various concentrations of PVP. Fourier transform infrared spectroscopy (FT-IR confirmed the presence of metal oxide bands for all the PVP concentrations and confirmed the absence of organic bands for PVP concentrations less than 55 g/L. Measurements of the magnetization value of the zinc ferrite nanoparticles were obtained at room temperature by using a vibrating sample magnetometer (VSM, which showed that, in the absence of PVP, the sample exhibited a paramagnetic behavior while, in the presence of PVP, samples have a super-paramagnetic behavior.

  1. Influence of the Polyvinyl Pyrrolidone Concentration on Particle Size and Dispersion of ZnS Nanoparticles Synthesized by Microwave Irradiation

    Directory of Open Access Journals (Sweden)

    Nayereh Soltani

    2012-09-01

    Full Text Available Zinc sulfide semiconductor nanoparticles were synthesized in an aqueous solution of polyvinyl pyrrolidone via a simple microwave irradiation method. The effect of the polymer concentration and the type of sulfur source on the particle size and dispersion of the final ZnS nanoparticle product was carefully examined. Microwave heating generally occurs by two main mechanisms: dipolar polarization of water and ionic conduction of precursors. The introduction of the polymer affects the heating rate by restriction of the rotational motion of dipole molecules and immobilization of ions. Consequently, our results show that the presence of the polymer strongly affects the nucleation and growth rates of the ZnS nanoparticles and therefore determines the average particle size and the dispersion. Moreover, we found that PVP adsorbed on the surface of the ZnS nanoparticles by interaction of the C–N and C=O with the nanoparticle’s surface, thereby affording protection from agglomeration by steric hindrance. Generally, with increasing PVP concentration, mono-dispersed colloidal solutions were obtained and at the optimal PVP concentration (5%, sufficiently small size and narrow size distributions were obtained from both sodium sulfide and thioacetamide sulfur sources. Finally, the sulfur source directly influences the reaction mechanism and the final particle morphology, as well as the average size.

  2. Polyvinyl pyrrolidone capped fluorescent anthracene nanoparticles for sensing fluorescein sodium in aqueous solution and analytical application for ophthalmic samples.

    Science.gov (United States)

    Bhopate, Dhanaji P; Mahajan, Prasad G; Garadkar, Kalyanrao M; Kolekar, Govind B; Patil, Shivajirao R

    2015-11-01

    Based on the known complexation ability between polyvinyl pyrrolidone (PVP) and fluorescein sodium (FL Na(+)), fluorescent PVP capped anthracene nanoparticles (PVP-ANPs) were prepared using a reprecipitation method for detection of fluorescein in aqueous solution using the fluorescence resonance energy transfer (FRET) approach. A dynamic light scattering histogram of PVP-ANPs showed narrower particle size distribution and the average particle size was 15 nm. The aggregation-induced enhanced emission (AIEE) of PVP-ANPs was red shifted from its monomer by 1087.22 cm(-1). The maximum emission was seen to occur at 420 nm. The presence of FL Na(+) in the vicinity of PVP-ANPs quenched the fluorescence of PVP-ANPs because of its adsorption on the surface of PVP-ANPs in aqueous suspension. The FL Na(+) and PVP-ANPs were brought close enough, typically to 7.89 nm, which was less than the distance of 10 nm that is required between the energy donor-acceptor molecule for efficient FRET. The quenching results fit into the Stern-Volmer relationship even at temperatures greater than ambient temperatures. The thermodynamic parameters determined from FRET results helped to propose binding mechanisms involving hydrophobic and electrostatic molecular interaction. The fluorescence quenching results were used further to develop an analytical method for estimation of fluorescein sodium from ophthalmic samples available commercially in the market.

  3. Fabrication and characterization of superparamagnetic poly(vinyl pyrrolidone)/poly(L-lactide)/Fe3O4 electrospun membranes

    Science.gov (United States)

    Savva, Ioanna; Constantinou, Demetris; Marinica, Oana; Vasile, Eugeniu; Vekas, Ladislau; Krasia-Christoforou, Theodora

    2014-02-01

    The fabrication of magnetoactive fibrous nanocomposite membranes based on poly(vinyl pyrrolidone) (PVP), poly(L-lactide) (PLLA) and pre-formed oleic acid coated magnetite nanoparticles (OA Fe3O4) is presented. The aforementioned materials have been prepared by means of the electrospinning technique following a single-step fabrication process. The PVP/PLLA/OA Fe3O4 nanocomposite membranes were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that provided information on the fiber diameters as well as on the morphological and dimensional characteristics of the OA Fe3O4 nanoparticles embedded within the fibers. The thermal stability of these materials was evaluated by means of thermal gravimetric analysis (TGA) measurements. Finally, vibrational sample magnetometry (VSM) analysis disclosed superparamagnetic behavior at room temperature. The combination of the hydrophilic, biocompatible and photo-crosslinkable PVP with the biodegradable PLLA and the superparamagnetic OA Fe3O4 nanoparticles within these materials allows for the future development of crosslinked fibrous magnetoactive nanocomposites exhibiting high stability in aqueous solutions, with potential use in biomedical and environmental applications.

  4. The effects of shear and particle shape on the physical adsorption of polyvinyl pyrrolidone on carbon nanoparticles

    Science.gov (United States)

    Vo, Minh D.; Papavassiliou, Dimitrios V.

    2016-08-01

    The effects of shear and particle shape on the physical adsorption of a polymer (polyvinyl pyrrolidone, PVP) on carbon nanoparticles (CNPs) were studied with dissipative particle dynamics (DPD) methods. It was found that the conformation of the polymer during adsorption and desorption from the nanoparticle can be classified into three possible types, i.e. adsorbed, shear-affected and separated, depending on the magnitude of the shear rate in the flow. Spherical and graphene sheet-shaped particles with adsorbed PVP were manipulated in a Couette flow to determine the threshold shear rates leading to changes in the polymer adsorption state. It was found that the polymer was stably adsorbed under higher shear conditions for graphene sheets. In addition, the end-to-end distance and the radius of gyration of the polymer adsorbate was clearly related to the adsorption state, as the polymer underwent a transition from adsorbed to the separated state when the shear rate increased. The critical shear rate at which the polymer desorbed from the surface could be useful in applications where nanoparticles can be used as a molecular delivery system. The physical adsorption and desorption of the same polymer molecules on a flat surface were also investigated. The desorption of the polymer from the flat surface occurred when the shearing force was stronger than the attraction between the PVP and the surface.

  5. A study on poly (N-vinyl-2-pyrrolidone covalently bonded NiTi surface for inhibiting protein adsorption

    Directory of Open Access Journals (Sweden)

    Hongyan Yu

    2016-12-01

    Full Text Available Near equiatomic NiTi alloys have been extensively applied as biomaterials owing to its unique shape memory effect, superelasticity and biocompatibility. It has been demonstrated that surfaces capable of preventing plasma protein adsorption could reduce the reactivity of biomaterials with human blood. This motivated a lot of researches on the surface modification of NiTi alloy. In the present work, following heat and alkaline treatment and silanization by trichlorovinylsilane (TCVS, coating of poly (N-vinyl-2-pyrrolidone (PVP was produced on the NiTi alloy by gamma ray induced chemical bonding. The structures and properties of modified NiTi were characterized and in vitro biocompatibility of plasma protein adsorption was investigated. The results indicated that heat treatment at 823 K for 1 h could result in the formation of a protective TiO2 layer with “Ni-free” zone on NiTi surface. It was found that PVP was covalently bonded on NiTi surface to create a hydrophilic layer for inhibiting protein adsorption on the surface. The present work offers a green approach to introduce a bioorganic surface on metal and other polymeric or inorganic substrates by gamma irradiation.

  6. Inductive effect of poly(vinyl pyrrolidone) on morphology and photocatalytic performance of Bi2WO6

    Science.gov (United States)

    Zhang, Qiang; Chen, Jinxing; Xie, Yunyun; Wang, Mozhen; Ge, Xuewu

    2016-04-01

    Bi2WO6 has great potential applications in the field of photocatalyst due to its excellent visible-light photocatalytic performance. This work studied the detailed morphological evolution of Bi2WO6 particles synthesized in a simple hydrothermal system induced by the stabilizer poly(vinyl pyrrolidone) (PVP). The XRD and HRTEM results show PVP would not change the crystal structure of Bi2WO6, but the distribution of PVP on the initially formed Bi2WO6 nanosheets will induce the crystal growth, resulting in a distinct morphology evolution of Bi2WO6 with the increase of the concentration of PVP. At the same time, with the increase of the molecular weight of PVP, the morphology of Bi2WO6 varied from simple sheet-like (S-BWO) to some complicated morphology, such as flower-like (F-BWO), red blood cell-like (B-BWO), and square-pillar-like (SP-BWO). The photocatalytic performances of Bi2WO6 with various morphologies on the decomposition of RhB under visible light irradiation reveal that S-BWO has the best photocatalytic performance, while SP-BWO has the worst. This work not only gives the explanation of the inductive effect of PVP molecular chains on the morphological formation of Bi2WO6 particles, but also provides the controllable way to the preparation of Bi2WO6 with various morphologies taking advantage of the stabilizer PVP.

  7. Antifouling and antimicrobial polymer membranes based on bioinspired polydopamine and strong hydrogen-bonded poly(N-vinyl pyrrolidone).

    Science.gov (United States)

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhang, Hongtao; Zhu, Baoku; Xu, Youyi

    2013-12-26

    A facile and versatile approach for the preparation of antifouling and antimicrobial polymer membranes has been developed on the basis of bioinspired polydopamine (PDA) in this work. It is well-known that a tightly adherent PDA layer can be generated over a wide range of material surfaces through a simple dip-coating process in dopamine aqueous solution. The resulting PDA coating is prone to be further surface-tailored and functionalized via secondary treatments because of its robust reactivity. Herein, a typical hydrophobic polypropylene (PP) porous membrane was first coated with a PDA layer and then further modified by poly(N-vinyl pyrrolidone) (PVP) via multiple hydrogen-bonding interactions between PVP and PDA. Data of water contact angle measurements showed that hydrophilicity and wettability of the membranes were significantly improved after introducing PDA and PVP layers. Both permeation fluxes and antifouling properties of the modified membranes were enhanced as evaluated in oil/water emulsion filtration, protein filtration, and adsorption tests. Furthermore, the modified membranes showed remarkable antimicrobial activity after iodine complexation with the PVP layer. The PVP layer immobilized on the membrane had satisfying long-term stability and durability because of the strong noncovalent forces between PVP and PDA coating. The strategy of material surface modification reported here is substrate-independent, and applicable to a broad range of materials and geometries, which allows effective development of materials with novel functional coatings based on the mussel-inspired surface chemistry.

  8. Synthesis, characterization and reactivity ratios of poly N-(p-bromophenyl-2-methacrylamide-Co-N-vinyl-2-pyrrolidone

    Directory of Open Access Journals (Sweden)

    D. Thirumoolan

    2016-03-01

    Full Text Available The methacrylamide monomer, N-(p-bromophenyl-2-methacrylamide (PBPMA was synthesized by reacting p-bromoaniline dissolved in ethylmethylketone (EMK with methacryloyl chloride in the presence of triethylamine. The copolymers of PBPMA with N-Vinyl-2-pyrrolidone (NVP were synthesized by free radical solution polymerization using EMK as a solvent at 70 ± 1 °C and benzoyl peroxide as a free radical initiator. The copolymerization behavior was studied in a wide composition interval with the mole fractions of PBPMA ranging from 0.20 to 0.80 in the feed. The copolymers were characterized by FT-IR, 1H NMR, 13C NMR and GPC. The solubility was tested in various polar and non polar solvents. The thermogravimetric analysis of the polymers showed that the thermal stability of the copolymer increases with PBPMA content. The copolymer composition was determined by elemental analysis. The monomer reactivity ratios were determined by the application of conventional linearization methods such as Fineman–Ross, Kelen–Tudos methods, and a non-linear error-in-variable model (EVM method using a computer program.

  9. Fabricating customized hydrogel contact lens

    Science.gov (United States)

    Childs, Andre; Li, Hao; Lewittes, Daniella M.; Dong, Biqin; Liu, Wenzhong; Shu, Xiao; Sun, Cheng; Zhang, Hao F.

    2016-10-01

    Contact lenses are increasingly used in laboratories for in vivo animal retinal imaging and pre-clinical studies. The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited. Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1.42 to 1.45 in the spectra range from 400 nm to 800 nm. The Young’s modulus (1.47 MPa) and hydrophobicity (with a sessile drop contact angle of 40.5°) have also been characterized experimentally. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens. Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies.

  10. Blends of zein and nylon-6

    Science.gov (United States)

    Blends of zein and nylon-6(55k)were used to produce solution cast films and electrospun fibers. Zein was blended with nylon-6 in formic acid solution. When the amount of nylon-6 was 8% or less a compatible blend formed. The blend was determined to be compatible based on physical property measurement...

  11. Processing silk hydrogel and its applications in biomedical materials.

    Science.gov (United States)

    Wang, Hai-Yan; Zhang, Yu-Qing

    2015-01-01

    This review mainly introduces the types of silk hydrogels, their processing methods, and applications. There are various methods for hydrogel preparation, and many new processes are being developed for various applications. Silk hydrogels can be used in cartilage tissue engineering, drug release materials, 3D scaffolds for cells, and artificial skin, among other applications because of their porous structure and high porosity and the large surface area for growth, migration, adhesion and proliferation of cells that the hydrogels provide. All of these advantages have made silk hydrogels increasingly attractive. In addition, silk hydrogels have wide prospects for application in the field of biomedical materials.

  12. Temperature responsive hydrogel nanofibers and nanoparticles

    Science.gov (United States)

    Ruokolainen, Janne

    2011-03-01

    Poly(N-isopropylacrylamide) (PNIPAM) is one of the most extensively investigated synthetic temperature-responsive polymers. In this work temperature-responsive PNIPAM based triblock copolymer hydrogels, their self-assembly and phase behavior in bulk, are described. Additionally, recent results from responsive hydrogel nanofibers and hydrogel nanoparticles are shown. It is known that block copolymers form well-organized nano structures in bulk or thin films when annealed thermally or in solvent vapours. However, in the case of nanofibers or nanoparticles, the annealing leads in most cases to aggregation and particle sintering. This work utilizes aerosol-based gas phase method where the preparation and annealing of hydrogel nanoparticles with well-organized, hierarchical inner structures are performed without any particle coagulation or sintering. In the method, the block copolymers assemble within aerosol nanoparticles to form, for instance, lamellar onion-like or gyroid inner structures.

  13. Responsive polyelectrolyte hydrogels and soft matter micromanipulation

    NARCIS (Netherlands)

    Glazer, P.J.

    2013-01-01

    This dissertation describes experimental studies on the mechanisms underlying the dynamic response of polyelectrolyte hydrogels when submitted to an external electric potential. In addition, we explore the possibilities of miniaturization and manipulation of responsive gels and other soft matter sys

  14. Hydrogels made from chitosan and silver nitrate.

    Science.gov (United States)

    Kozicki, Marek; Kołodziejczyk, Marek; Szynkowska, Małgorzata; Pawlaczyk, Aleksandra; Leśniewska, Ewa; Matusiak, Aleksandra; Adamus, Agnieszka; Karolczak, Aleksandra

    2016-04-20

    This work describes a gelation of chitosan solution with silver nitrate. Above the critical concentration of chitosan (c*), continuous hydrogels of chitosan-silver can be formed. At lower concentrations, the formation of nano- and micro-hydrogels is discussed. The sol-gel analysis was performed to characterise the hydrogels' swelling properties. Moreover, the following were employed: (i) mechanical testing of hydrogels, (ii) inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the measurement of silver concentration, (iii) scanning electron microscopy (SEM) to examine the morphology of products obtained, and (iv) dynamic light scattering (DLS) and UV-vis spectrophotometry to examine products formed at low concentration of chitosan (chydrogels were used for modification of cotton fabric in order to give it antimicrobial properties. The products obtained acted against Escherichia coli and Bacillus subtilis apart from the chitosan used that showed no such activity.

  15. Polyamide blend-based nanocomposites: A review

    Directory of Open Access Journals (Sweden)

    W. S. Chow

    2015-03-01

    Full Text Available Polymer blend nanocomposites have been considered as a stimulating route for creating a new type of high performance material that combines the advantages of polymer blends and the merits of polymer nanocomposites. In nanocomposites with multiphase matrices, the concept of using nanofillers to improve select properties (e.g., mechanical, thermal, chemical, etc of a polymer blend, as well as to modify and stabilize the blend morphology has received a great deal of interest. This review reports recent advances in the field of polyamide (PA blend-based nanocomposites. Emphasis is placed on the PA-rich blends produced by blending with other thermoplastics in the presence of nanofillers. The processing and properties of PA blend-based nanocomposites with nanofillers are discussed. In addition, the mechanical properties and morphology changes of PA blends with the incorporation of nanofillers are described. The issues of compatibility and toughening of PA blend nanocomposites are discussed, and current challenges are highlighted.

  16. Further development of a morphine hydrogel suppository.

    OpenAIRE

    Cole, L.; Hanning, C. D.; Robertson, S.; Quinn, K

    1990-01-01

    1. A sustained release monolithic morphine hydrogel suppository (MHS) was developed and administered to five volunteers. 2. The MHS delivered a mean of 55 mg morphine over 12 h. The mean plasma morphine concentration was 15 ng ml-1 from 2 to 12 h after administration. 3. Plasma morphine concentrations were comparable with those reported for the same dose given orally over the same time period. 4. The morphine hydrogel suppository appears to be an effective means of delivering morphine and may...

  17. Multitriggered Shape-Memory Acrylamide-DNA Hydrogels.

    Science.gov (United States)

    Lu, Chun-Hua; Guo, Weiwei; Hu, Yuwei; Qi, Xiu-Juan; Willner, Itamar

    2015-12-23

    Acrylamide-acrylamide nucleic acids are cross-linked by two cooperative functional motives to form shaped acrylamide-DNA hydrogels. One of the cross-linking motives responds to an external trigger, leading to the dissociation of one of the stimuli-responsive bridges, and to the transition of the stiff shaped hydrogels into soft shapeless states, where the residual bridging units, due to the chains entanglement, provide an intrinsic memory for the reshaping of the hydrogels. Subjecting the shapeless states to counter stimuli restores the dissociated bridges, and regenerates the original shape of the hydrogels. By the cyclic dissociation and reassembly of the stimuli-responsive bridges, the reversible switchable transitions of the hydrogels between stiff shaped hydrogel structures and soft shapeless states are demonstrated. Shaped hydrogels bridged by K(+)-stabilized G-quadruplexes/duplex units, by i-motif/duplex units, or by two different duplex bridges are described. The cyclic transitions of the hydrogels between shaped and shapeless states are stimulated, in the presence of appropriate triggers and counter triggers (K(+) ion/crown ether; pH = 5.0/8.0; fuel/antifuel strands). The shape-memory hydrogels are integrated into shaped two-hydrogel or three-hydrogel hybrid structures. The cyclic programmed transitions of selective domains of the hybrid structures between shaped hydrogel and shapeless states are demonstrated. The possible applications of the shape-memory hydrogels for sensing, inscription of information, and controlled release of loads are discussed.

  18. Blended Learning: The Student Viewpoint

    African Journals Online (AJOL)

    learning and development to the needs of individuals by integrating the innovative and .... Learners represent different generations, different personality types, and different .... learning, social presence and satisfaction in a blended learning.

  19. Blended Learning: The Student Viewpoint

    African Journals Online (AJOL)

    ... the needs of students who are not in a position to attend traditional contact classes ... Keywords: Blended learning, Online learning, Students' perceptions. Access this ... lecture time. Online .... The BL content encouraged me to learn. ‑. 4. 9.3.

  20. Comparative Studies with N-Methyl-2-Pyrrolidone and Furfural As Solvents for Extraction of Lube Distillates Etude comparative de deux solvants, la n-methyl-2 pyrrolidone et le furfural, pour l'extraction de distillats pour huiles lubrifiantes

    Directory of Open Access Journals (Sweden)

    Krishna R.

    2006-11-01

    Full Text Available Solvent extraction of spindle raw lube distillate from Oman crude using n-methyl pyrrolidone (NMP containing 1. 5wt. % water has been studied using a six-stage all-glass mixer-settler. Results of three operating temperatures with NMP are reported. A 65-55°C extraction temperature appears to be most appropriate for this stock. Data obtained at this temperature have been compared with those for furfural on the basis of phase boundary curves, extraction and lube refining indices and selectivity. Comparison of the results shows NMP to be more selective as far as raffinate yield is concerned. It requires lower operating solvent-to-feed ratios and lower temperatures. On étudie dans cet article l'extraction par solvant de distillats bruts pour huiles lubrifiantes spindles au moyen de n-méthyl pyrrolydone (NMP contenant 1,5 % d'eau en poids, dans une unité en verre constituée par une batterie de six mélangeurs-décanteurs. On présente les résultats relatifs à trois températures de fonctionnement avec la NMP. Une température d'extraction de 66-55°C est celle qui convient le mieux pour cette huile de base. On compare les résultats obtenus à cette température avec ceux du furfural, en ce qui concerne les courbes de solubilité, les indices de raffinage et d'extraction, et les sélectivités. La comparaison des résultats montre que la NMP est plus sélective et conduit à un rendement de raffinat plus élevé. Elle nécessite des taux de solvant par rapport à la charge plus faibles ainsi que des températures d'extraction plus basses.

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

    Directory of Open Access Journals (Sweden)

    Enas M. Ahmed

    2015-03-01

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

  2. Blended Learning in der Wirtschaftsinformatik

    OpenAIRE

    Gabriel, Roland; Weber, Peter

    2011-01-01

    Der vorliegende Projektbericht stellt das Blended Learning-Konzept und insbesondere ein darin enthaltenes Sonderpunkteprogramm zweier Vorlesungen vor, die auf dem RuhrCampusOnline der drei Ruhrgebietsuniversitäten angeboten werden. Der Artikel entwickelt sich dabei vom Allgemeinen zum Speziellen: Nach einer Erläuterung der Rahmenbedingungen in Form des RuhrCampusOnline und des Lehrmoduls „Management & Information“ wird zunächst das Blended Learning-Konzept der Lehrveranstaltungen vorgestellt....

  3. Synthesis and characterization of novel carboxymethylcellulose hydrogels and carboxymethylcellulolse-hydrogel-ZnO-nanocomposites.

    Science.gov (United States)

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

    2013-06-05

    New approach for preparation of CMC hydrogels was undertaken through reacting CMC with either malic, succinic or citric acid. Characteristics of the hydrogels, as monitored by the swelling behavior, FTIR, SEM, EDX, TEM and XRD were dependent on nature and concentration of the polycarboxylic acid, time and temperature of curing. The best practice achieved from these studies was harnessed to synthesize and characterize CMC hydrogel-ZnO-nanocomposites with additional study pertaining to the antibacterial activity of the nanocomposites. CMC hydrogel with excellent swelling behavior could be prepared by adding succinic acid (0.5%) to CMC solution then drying the obtained paste at 80 °C for 5 min followed by curing at 120 °C for 3 min. Similarly, addition of ZnNO3 solution to the CMC paste results in CMC hydrogel-ZnO-nanocomposites having biocidal activity to gram +ve and gram -ve bacteria.

  4. A pH-sensitive Modified Polyacrylamide Hydrogel

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A pH-sensitive modified polyacrylamide hydrogel was prepared by two steps and the modified polyacrylamide was characterized by 1HNMR spectrum. The surface morphology and swelling behavior of the hydrogels were investigated.

  5. New in situ crosslinking chemistries for hydrogelation

    Science.gov (United States)

    Roberts, Meredith Colleen

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

  6. Preparation and characterization of chitosan/genipin/poly(N-vinyl-2-pyrrolidone) films for controlled release drugs

    Energy Technology Data Exchange (ETDEWEB)

    Aldana, Ana Agustina, E-mail: aaldana@fcq.unc.edu.ar [Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba (UNC), Edificio de Ciencias II, Medina Allende y Haya de la Torre, Ciudad Universitaria, Cordoba 5000 (Argentina); Gonzalez, Agustin, E-mail: agustingonzalez@fcq.unc.edu.ar [Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba (UNC), Edificio de Ciencias II, Medina Allende y Haya de la Torre, Ciudad Universitaria, Cordoba 5000 (Argentina); Strumia, Miriam C., E-mail: mcs@fcq.unc.edu.ar [Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba (UNC), Edificio de Ciencias II, Medina Allende y Haya de la Torre, Ciudad Universitaria, Cordoba 5000 (Argentina); Martinelli, Marisa, E-mail: mmartinelli@fcq.unc.edu.ar [Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba (UNC), Edificio de Ciencias II, Medina Allende y Haya de la Torre, Ciudad Universitaria, Cordoba 5000 (Argentina)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Cross-linked chitosan films using genipin and/or PVP. Black-Right-Pointing-Pointer Propranolol hydrochloride was used like a model drug to release studies. Black-Right-Pointing-Pointer Incorporating PVP improves mechanical and diffusion properties. Black-Right-Pointing-Pointer Ch-Gen 0.10% and Ch-Gen 0.10%-PVP have optimal behavior. - Abstract: The study of the physicochemical and functional properties of chitosan films cross-linked with genipin and poly(N-vinyl-2-pyrrolidone) (PVP) was performed in this work. Cross-linked films were prepared by casting method from acetic acid solutions. The structure and physical properties of the films were analyzed by infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy ({sup 13}C NMR), differential scanning calorimetry (DSC) and mechanical testings. Propranolol hydrochloride was used like a model drug to determine the behavior of drug release from films. The drug release capacity was measured and compared with the degree of cross-linking, mechanical properties and swelling index. There was an appropriate balance of hydrophilicity, mechanical properties and diffusion by the incorporation of PVP into the networks cross-linked with genipin. The combination of both cross-linkers allows obtaining a soft and tough material potentially applicable as a controlled release. This research represents the first report where both cross-linkers, chemical and ionic agents, are used for obtaining films. These studies suggest that the chitosan films prepared here are promising drug delivery systems for buccal application, with thermal stability and acceptable mechanical properties. Buccal films may be preferred in terms of flexibility and comfort.

  7. Gellan gum microgel-reinforced cell-laden gelatin hydrogels

    OpenAIRE

    Shin, Hyeongho; Olsen, Bradley D.; Khademhosseini, Ali

    2013-01-01

    The relatively weak mechanical properties of hydrogels remain a major drawback for their application as load-bearing tissue scaffolds. Previously, we developed cell-laden double-network (DN) hydrogels that were composed of photocrosslinkable gellan gum (GG) and gelatin. Further research into the materials as tissue scaffolds determined that the strength of the DN hydrogels decreased when they were prepared at cell-compatible conditions, and the encapsulated cells in the DN hydrogels did not f...

  8. Research on the printability of hydrogels in 3D bioprinting

    OpenAIRE

    Yong He; FeiFei Yang; HaiMing Zhao; Qing Gao; Bing Xia; JianZhong Fu

    2016-01-01

    As the biocompatible materials, hydrogels have been widely used in three- dimensional (3D) bioprinting/organ printing to load cell for tissue engineering. It is important to precisely control hydrogels deposition during printing the mimic organ structures. However, the printability of hydrogels about printing parameters is seldom addressed. In this paper, we systemically investigated the printability of hydrogels from printing lines (one dimensional, 1D structures) to printing lattices/films ...

  9. Wavelet and Blend maps for texture synthesis

    Directory of Open Access Journals (Sweden)

    Du Jin-Lian

    2011-04-01

    Full Text Available blending is now a popular technology for large realtime texture synthesis .Nevertheless, creating blend map during rendering is time and computation consuming work. In this paper, we exploited a method to create a kind of blend tile which can be tile together seamlessly. Note that blend map is in fact a kind of image, which is Markov Random Field, contains multiresolution signals, while wavelet is a powerful way to process multiresolution signals, we use wavelet to process the traditional blend tile. After our processing steps, the result blend tile become smooth and suitable for tiling, with no important features lost. Using this kind blend tile, many computation resources for computing blend map during texture synthesizing is saved. The experimental results shows that our method may successfully process many traditional blend tiles.

  10. Performance of Blended Learning in University Teaching:

    Directory of Open Access Journals (Sweden)

    Michael Reiss

    2010-07-01

    Full Text Available Blended learning as a combination of classroom teaching and e-learning has become a widely represented standard in employee and management development of companies. The exploratory survey “Blended Learning@University” conducted in 2008 investigated the integration of blended learning in higher education. The results of the survey show that the majority of participating academic teachers use blended learning in single courses, but not as a program of study and thus do not exploit the core performance potential of blended learning. According to the study, the main driver of blended learning performance is its embeddedness in higher education. Integrated blended programs of study deliver the best results. In blended learning, learning infrastructure (in terms of software, culture, skills, funding, content providing, etc. does not play the role of a performance driver but serves as an enabler for blended learning.

  11. Viability of pHEMA Hydrogels as Coating in Human Synovial Joint Prosthesis

    Directory of Open Access Journals (Sweden)

    V.P. Bavaresco

    2002-10-01

    Full Text Available In artificial joints, the bone part is usually substituted by a metallic component with high corrosion and strength resistance while the articular cartilage is replaced by a polymer. Use of thin layer of a compliant material acting as a bearing surface in human replacement joints has recently generated considerable interest. This work analyses the coating of a solid porous substrate of Ultra High Molecular Weight Polyethylene (UHMWPE with a poly (2-hydroxyethyl methacrylate (pHEMA and two sIPN-type blends: pHEMA-cellulose acetate butyrate (CAB and pHEMA-poly (ethyl methacrylate (PEM using 5.0% (w/w of the crosslinking agent and 11.0% (w/w of the linear reinforcing polymer. The wear resistance of the coating materials was evaluated in a TRI PIN ON DISK type equipment and the damage extension was characterized by Scanning Electron Microscopy (SEM. Preliminary qualitative tests were performed with the goal to identifying the hydrogels show the minimal required properties concerning wear strength. The pHEMA coating was completely destroyed during the first wear cycles, characterizing its low shear strength. By the other hand, after the complete experiment, both pHEMA-CAB and pHEMA-PEM blends showed a slightly improvement of abrasive and adhesive wear. This result indicates that the studied blends are promising materials to be used as compliant surfaces in joint prosthesis.

  12. Evaluation of poly(methyl methacrylate)/poly(vinylpyrrolidone)/poly(ethylene oxide) blends by solution and solid state NMR; Avaliacao da mistura fisica de poli(metacrilato de metila)/polivinilpirrolidona/poli(oxido de etileno) por ressonancia magnetica nuclear em solucao e solido

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, Teresinha M.F.F. [Instituto Nacional da Propriedade Industrial (INPI), Rio de Janeiro, RJ (Brazil)]. E-mail: teresinh@inpi.gov.br; Tavares, Maria Ines B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas]. E-mail: mibt@ima.ufrj.br

    2001-07-01

    Ternary blends formed by poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP)/poly(ethylene oxide) (PEO) have been investigated applying solution and solid state nuclear magnetic resonance. From solution NMR it can be seen that no change in the chemical shift of the microstructure detected in the carbonyl and C quaternary carbons of PMMA was found. However a small change in the form of those signals was observed. This change was attributed to the plasticization effect. The solid state techniques showed that both PEO and PVP acts as a plasticizer in different ways, which depends on these proportions that derives from different dynamical behavior. (author)

  13. pH-sensitive hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Jing-Fun, Yaung.

    1993-01-01

    This work dealt with the diffusant release from the polyvinyl-pyrrolidone-polyacrylic acid (PVP-PAA) semi-interpenetrating network (semi-IPN) film when the film was placed in separate aqueous dissolution media with various pH values. The pH effect on the swelling behavior of the film and the rates of diffusant release from the film were studied. The PVP-PAA semi-IPN films and the PVP-PAA complexes were prepared from photopolymerization of the mixture of PVP and acrylic acid, in the presence of benzin methyl ether. The PVP-PAA complexes were characterized by means of DSC and FT-IR. The PVP-PAA semi-IPN films with various percentages of a crosslinking agent were investigated. The study of pH effect on the swelling of the semi-IPN film was carried out in 0.1 N HCl solution, pH 3.0 and 6.0 buffers. The swelling rate of PVP-PAA semi-IPN film in pH 6.0 buffer was much higher than the rates in 0.1 N HCl and pH 3.0 buffer. The chemical to be released from the film was incorporated during the film preparation and the diffusant used was either caffeine (hydrogen-bonding-acceptor) or salicylamide (hydrogen-bonding-donator). The diffusant release from the PVP-PAA semi-IPN in 0.1 N HCl solution and in the phosphate buffers with various pH values was investigated. Release rate was faster in high pH media. The chemical valve function of the PVP-PAA semi-IPN film in controlling release rate was studied by alternating the dissolution medium between 0.1N HCl solution and pH 6.0 buffer. Consistently, the release rate increased when the dissolution medium was changed from 0.1 N HCl solution to pH 6.0 buffer, and the rate dropped while the medium was was switched from pH 6.0 buffer to 0.1 N HCl solution. Finally, the effects of the type of crosslinking agent, the percentage of crosslinking agent used, and the molar ratio of PVP/AA on the diffusant release from the PVP-PAA semi-IPN film were explored.

  14. Experimental Study on Self-assembly of KLD-12 Peptide Hydrogel and 3-D Culture of MSC Encapsulated within Hydrogel In Vitro

    Institute of Scientific and Technical Information of China (English)

    Jianhua SUN; Qixin ZHENG

    2009-01-01

    o-fiber hydrogel in vitro. MSCs in KLD-12 peptide hydrogel grew well and proliferated with the culture time. KLD-12 peptide hydrogel can serve as an excellent injectable material of biological scaffolds in tissue engineering of IVD.

  15. A novel cellulose hydrogel prepared from its ionic liquid solution

    Institute of Scientific and Technical Information of China (English)

    LI Lu; LIN ZhangBi; YANG Xiao; WAN ZhenZhen; CUI ShuXun

    2009-01-01

    A novel cellulose hydrogel is prepared by regenerating cellulose from its ionic liquid solution. The transparency cellulose hydrogel presents a good chemical stability and an acceptable mechanical property. This non-toxic cellulose hydrogel should be biocompatibie and may be useful in the future as a biomaterial.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  17. Molecular dynamic simulations of the water absorbency of hydrogels.

    Science.gov (United States)

    Ou, Xiang; Han, Qiang; Dai, Hui-Hui; Wang, Jiong

    2015-09-01

    A polymer gel can imbibe solvent molecules through surface tension effect. When the solvent happens to be water, the gel can swell to a large extent and forms an aggregate called hydrogel. The large deformation caused by such swelling makes it difficult to study the behaviors of hydrogels. Currently, few molecular dynamic simulation works have been reported on the water absorbing mechanism of hydrogels. In this paper, we first use molecular dynamic simulation to study the water absorbing mechanism of hydrogels and propose a hydrogel-water interface model to study the water absorbency of the hydrogel surface. Also, the saturated water content and volume expansion rate of the hydrogel are investigated by building a hydrogel model with different cross-linking degree and by comparing the water absorption curves under different temperatures. The sample hydrogel model used consists of Polyethylene glycol diglycidyl ether (PEGDGE) as epoxy and the Jeffamine, poly-oxy-alkylene-amines, as curing agent. The conclusions obtained are useful for further investigation on PEGDGE/Jeffamine hydrogel. Moreover, the simulation methods, including hydrogel-water interface modeling, we first propose are also suitable to study the water absorbing mechanism of other hydrogels.

  18. A hydrogel-based enzyme-loaded polymersome reactor

    NARCIS (Netherlands)

    Hoog, de Hans-Peter; Arends, Isabel W.C.E.; Rowan, Alan E.; Cornelissen, Jeroen J.L.M.; Nolte, Roeland J.M.

    2010-01-01

    In this study we report the immobilization of enzyme-containing polymersomes into a macromolecular hydrogel. Whereas free enzyme shows progressive leakage from the hydrogel in a period of days, leakage of the polymersome-protected enzyme is virtually absent. The preparation of the hydrogel occurs un

  19. Hydrogels for an accommodating intraocular lens. An explorative study

    NARCIS (Netherlands)

    de Groot, JH; Spaans, CJ; van Calck, RV; van Beijma, FJ; Norrby, S; Pennings, AJ

    2003-01-01

    In this study it was investigated whether hydrogels could be used for an accommodating lens. The requirements of such a hydrogels are a low modulus, high refractive index, transparency, and strength. Since conventional hydrogels do not possess this combination of properties, a novel preparation meth

  20. A hydrogel-based enzyme-loaded polymersome reactor

    NARCIS (Netherlands)

    de Hoog, H.P.M.; de Hoog, Hans-Peter; Arends, Isabel W.C.E.; Rowan, Alan E.; Cornelissen, Jeroen Johannes Lambertus Maria; Nolte, Roeland J.M.

    2010-01-01

    In this study we report the immobilization of enzyme-containing polymersomes into a macromolecular hydrogel. Whereas free enzyme shows progressive leakage from the hydrogel in a period of days, leakage of the polymersome-protected enzyme is virtually absent. The preparation of the hydrogel occurs

  1. Resveratrol immobilization and release in polymeric hydrogels; Incorporacao e liberacao de resveratrol em hidrogeis polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Momesso, Roberta Grazzielli Ramos Alves Passarelli

    2010-07-01

    Resveratrol (3, 4', 5-trihydroxystilbene) is a polyphenolic produced by a wide variety of plants in response to injury and found predominantly in grape skins. This active ingredient has been shown to possess benefits for the health, such as the antioxidant capacity which is related to the prevention of several types of cancer and skin aging. However, the oral bioavailability of resveratrol is poor and makes its topical application interesting. The purpose of this study was to immobilize resveratrol in polymeric hydrogels to obtain a release device for topical use. The polymeric matrices composed of poli(N-vinyl-2-pyrrolidone) (PVP), poly(ethyleneglycol) (PEG) and agar or PVP and glycerol irradiated at 20 kGy dose were physical-chemically characterized by gel fraction and swelling tests and its preliminary biocompatibility by in vitro test of cytotoxicity using the technique of neutral red uptake. Due to low solubility of resveratrol in water, the addition of 2% ethanol to the matrices was verified. All matrices showed a high crosslinking degree, capacity of swelling and the preliminary cytotoxicity test showed nontoxicity effect. The devices were obtained by resveratrol immobilization in polymeric matrices, carried out in a one-or-two-steps process, that is, before or after irradiation, respectively. The one step resveratrol devices were characterized by gel fraction, swelling tests and preliminary biocompatibility, and their properties were maintained even after the resveratrol incorporation. The devices containing 0,05% of resveratrol obtained by one-step process and 0,1% of resveratrol obtained by two-steps process were submitted to the release test during 24 h. Resveratrol quantification was done by high performance liquid chromatography (HPLC). The results obtained in the kinetics of release showed that only the devices obtained by two-step process release the resveratrol, which demonstrate antioxidant capacity after the release. (author)

  2. Hydrogel Actuation by Electric Field Driven Effects

    Science.gov (United States)

    Morales, Daniel Humphrey

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

  3. Investigation of Complexation of Linear Poly(N-vinyl-2-pyrrolidone with Poly(methacrylic acid-co-methyl methacrylate Gel

    Directory of Open Access Journals (Sweden)

    Guoqin Liu

    2011-01-01

    Full Text Available The contraction of poly(methacrylic acid-co-methyl methacrylate (P(MAA-co-MMA gel induced by complexation with linear poly(N-vinyl-2-pyrrolidone (PVP is quite different from that of poly(acrylic acid (PAA or poly(methacrylic acid (PMAA gel. It was found that the concentration of PVP has a strong effect on the complexation with P(MAA-co-MMA gel. When PVP was introduced into the P(MAA-co-MMA network, its dynamic mechanic properties vary greatly between complexed and uncomplexed networks. It had the following results: (1 the higher modulus ratio; (2 a slight contraction of gel.

  4. Magnetic hyaluronate hydrogels: preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Tóth, Ildikó Y., E-mail: Ildiko.Toth@chem.u-szeged.hu; Veress, Gábor; Szekeres, Márta; Illés, Erzsébet; Tombácz, Etelka, E-mail: tombacz@chem.u-szeged.hu

    2015-04-15

    A novel soft way of hyaluronate (HyA) based magnetic hydrogel preparation was revealed. Magnetite nanoparticles (MNPs) were prepared by co-precipitation. Since the naked MNPs cannot be dispersed homogenously in HyA-gel, their surface was modified with natural and biocompatible chondroitin-sulfate-A (CSA) to obtain CSA-coated MNPs (CSA@MNPs). The aggregation state of MNPs and that loaded with increasing amount of CSA up to 1 mmol/g was measured by dynamic light scattering at pH~6. Only CSA@MNP with ≥0.2 mmol/g CSA content was suitable for magnetic HyA-gel preparation. Rheological studies showed that the presence of CSA@MNP with up to 2 g/L did not affect the hydrogel's rheological behavior significantly. The results suggest that the HyA-based magnetic hydrogels may be promising formulations for future biomedical applications, e.g. as intra-articular injections in the treatment of osteoarthritis. - Highlights: • Novel hyaluronate(HyA)-based biocompatible magnetic hydrogels were prepared. • Chondroitin-sulfate-A coating is needed to disperse magnetite particles in HyA-gel. • Rheological behavior of hydrogels was independent of the magnetite content (<2 g/L). • Gels remained in stable and homogeneously dispersed state even after 90 days storage. • Magnetic HyA-gels are promising candidates for use as intra-articular injection.

  5. Poly(ethylene glycol) hydrogel microstructures encapsulating living cells

    Science.gov (United States)

    Koh, Won-Gun; Revzin, Alexander; Pishko, Michael V.

    2002-01-01

    We present an easy and effective method for the encapsulation of cells inside PEG-based hydrogel microstructures fabricated using photolithography. High-density arrays of three-dimensional microstructures were created on substrates using this method. Mammalian cells were encapsulated in cylindrical hydrogel microstructures of 600 and 50 micrometers in diameter or in cubic hydrogel structures in microfluidic channels. Reducing lateral dimension of the individual hydrogel microstructure to 50 micrometers allowed us to isolate 1-3 cells per microstructure. Viability assays demonstrated that cells remained viable inside these hydrogels after encapsulation for up to 7 days.

  6. 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.

  7. Thermo-mechanical behavior of graphene oxide hydrogel

    Science.gov (United States)

    Ghosh, Rituparna; Deka Boruah, Buddha; Misra, Abha

    2017-02-01

    Graphene oxide hydrogel with encapsulated water presents a unique structural characteristic similar to open cell foam. It is demonstrated that the encapsulated water plays a vital role in tailoring compressive behavior of graphene oxide hydrogel under varying thermal conditions. The present study is focused on systematically evaluating both the temperature and frequency dependence on compressive behavior of hydrogel to elucidate the evolution of stiffness in a wider temperature range. The stiffness of the hydrogel is further tailored through encapsulation of nanoparticles to achieve an extraordinary enhancement in storage modulus. It is concluded that the change in phase of water provides a large gradient in the stiffness of the hydrogel.

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

    Science.gov (United States)

    Michálek, J; Prádný, M; Artyukhov, A; Slouf, M; Smetana, K

    2005-08-01

    Four series of macroporous hydrogels based on crosslinked copolymers of 2-hydroxyethyl methacrylate (HEMA)-sodium methacrylate (MANa), copolymer HEMA-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (MOETACl), terpolymer HEMA-MANa-MOETACl and on a polyelectrolyte complex were used as carriers for immobilization of proteins, chicken egg white albumin and avidin. The adsorption capacity of the hydrogels for the two proteins, kinetics and pH dependence of albumin adsorption and desorption were studied. The morphology of the hydrogels with and without immobilized albumin was studied by low-vacuum scanning electron microscopy.

  9. NURBS curve blending using extension

    Institute of Scientific and Technical Information of China (English)

    Yong-jin LIU; Rong-qi QIU; Xiao-hui LIANG

    2009-01-01

    Curve and surface blending is an important operation in CAD systems, in which a non-uniform rational B-spline (NURBS) has been used as the de facto standard. In local comer blending, two curves intersecting at that comer are first made disjoint, and then the third blending curve is added-in to smoothly join the two curves with G1-or G2-continuity. In this paper we present a study to solve the joint problem based on curve extension. The following nice properties of this extension algorithm are exploited in depth: (1) The parameterization of the original shapes does not change; (2) No additional fragments are created.Various examples are presented to demonstrate that our solution is simple and efficient.

  10. Blended Learning as Transformational Institutional Learning

    Science.gov (United States)

    VanDerLinden, Kim

    2014-01-01

    This chapter reviews institutional approaches to blended learning and the ways in which institutions support faculty in the intentional redesign of courses to produce optimal learning. The chapter positions blended learning as a strategic opportunity to engage in organizational learning.

  11. NESDIS Blended Rain Rate (RR) Products

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The blended Rain Rate (RR) product is derived from multiple sensors/satellites. The blended products were merged from polar-orbiting and geostationary satellite...

  12. Production of Silk & Wool Blended Worsted Cloth

    Institute of Scientific and Technical Information of China (English)

    段亚峰; 许琳

    2004-01-01

    Wool & silk blended fancy suiting is desinged. Through trial-production with silk sliver and Australian wool top, the spinning technology is investigated, and the relationship of spinning technology, blending ratio and yam construction is discussed.

  13. Blended Learning as Transformational Institutional Learning

    Science.gov (United States)

    VanDerLinden, Kim

    2014-01-01

    This chapter reviews institutional approaches to blended learning and the ways in which institutions support faculty in the intentional redesign of courses to produce optimal learning. The chapter positions blended learning as a strategic opportunity to engage in organizational learning.

  14. Statistical methods for assessment of blend homogeneity

    DEFF Research Database (Denmark)

    Madsen, Camilla

    2002-01-01

    as powder blends there is no natural unit or amount to define a sample from the blend, and partly that current technology does not provide a method of universally collecting small representative samples from large static powder beds. In the thesis a number of methods to assess (in)homogeneity are presented...... of internal factors to the blend e.g. the particle size distribution. The relation between particle size distribution and the variation in drug content in blend and tablet samples is discussed. A central problem is to develop acceptance criteria for blends and tablet batches to decide whether the blend...... blend or batch. In the thesis it is shown how to link sampling result and acceptance criteria to the actual quality (homogeneity) of the blend or tablet batch. Also it is discussed how the assurance related to a specific acceptance criteria can be obtained from the corresponding OC-curve. Further...

  15. Swelling Behaviour of a Non-ionic Poly(N-vinyl-2-Pyrrolidone) Gel in a Linear Poly(Acrylic Acid) Solution%非离子聚(N-乙烯基-2-吡咯烷酮)凝胶在线型聚(丙烯酸) 溶液中的溶胀特性

    Institute of Scientific and Technical Information of China (English)

    石家华; 周慧珍; 赵纪冬; 高青雨

    2001-01-01

    The swelling behaviour of a non-ionic poly(N-vinyl-2-pyrrolidone) hydrogel in a linear poly(acrylic acid) solution upon the influence of chain lengh,pH,ionic strength,and water/dimethyl sulfoxide composition was studied.The sharp shrinkage of the gel volume within a narrow range of polyacid concetration takes place as a result of the formation of an intermacromolecular gel-polymer complex on the base of hydrogen bonding.The swelling behaviour strongly depends on the chain length of the polyacid rather than on the ionic strengh.With the increase of pH value and changing water/dimethyl sulfoxide composition the gel reswelling is induced.%研究了在线型聚(丙烯酸)(PAA)溶液中链长、pH、离子强度和水/二甲亚砜混合溶剂组成对非离子聚(N-乙烯基-2-吡咯烷酮)(PVP)水凝胶溶胀特性的影响. 发现聚酸浓度的变化引起凝胶显著的体积相变,这是因为凝胶和聚合物通过氢键形成了大分子间凝胶-聚合物复合物. 凝胶的溶胀特性取决于聚酸的链长而不是离子强度. 随着pH值和水/二甲亚砜混合溶剂组成的变化,凝胶的溶胀率(SR)发生变化.

  16. Hydrogels: a journey from diapers to gene delivery.

    Science.gov (United States)

    Chawla, Pooja; Srivastava, Alok Ranjan; Pandey, Priyanka; Chawla, Viney

    2014-02-01

    Hydrogels are the biomaterials comprising network of natural or synthetic polymers capable of absorbing large amount of water. Hydrogels are "Smart Gels" or "Intelligent Gels" which can be made to respond to the various environmental conditions like temperature, pH, magnetic/electric field, ionic strength, inflammation, external stress etc. There are numerous potential applications of hydrogels in modern day life ranging from a diaper to gene delivery. This review succinctly describes the classification, properties and preparation methods along with numerous diverse applications of hydrogels like agricultural hydrogels, hydrogel for drug delivery, sensing, dental adhesives, wound healing and tissue regeneration, diet aid and gastric retention and in tissue engineering etc. Hydrogels can be regarded as highly valuable biomaterials for human-beings.

  17. Commercialization of hydrogel for topical anesthesia by irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Youngchang; Kang, Philhyun; Lim, Younmook; Gwon, Huijeong; Park, Jongseok

    2013-09-15

    - The technologies to develop topical asesthetic hydrogels were developed and the preliminary clinical test was carried out for the prepared hydrogels at Kyunghee University. - The topical asesthetic hydrogels made by radiation are founded to have appropriate strengths and accelerant delivery behavior for lidocane which has a function of anesthetic. - New type of Hydrogels were designed in these experiments so that they had voids in hydrogels which led to much more absorption of exudate. - Several companies and Philippine Nuclear Research Institute(PNRI) are interested in our technologies to produce the hydrogels, we signed a MOA to support PNRI technically in the field of hydrogels and perform the general technical cooperation between Advanced Radiation Technology and PNRI.

  18. pH-Sensitive Hydrogel for Micro-Fluidic Valve

    Directory of Open Access Journals (Sweden)

    Zhengzhi Yang

    2012-07-01

    Full Text Available The deformation behavior of a pH-sensitive hydrogel micro-fluidic valve system is investigated using inhomogeneous gel deformation theory, in which the fluid-structure interaction (FSI of the gel solid and fluid flow in the pipe is considered. We use a finite element method with a well adopted hydrogel constitutive equation, which is coded in commercial software, ABAQUS, to simulate the hydrogel valve swelling deformation, while FLUENT is adopted to model the fluid flow in the pipe of the hydrogel valve system. The study demonstrates that FSI significantly affects the gel swelling deformed shapes, fluid flow pressure and velocity patterns. FSI has to be considered in the study on fluid flow regulated by hydrogel microfluidic valve. The study provides a more accurate and adoptable model for future design of new pH-sensitive hydrogel valves, and also gives a useful guideline for further studies on hydrogel fluidic applications.

  19. Radiation processed hydrogel of poly (vinyl alcohol) with biodegradable polysaccharides.

    Science.gov (United States)

    Chowdhury, M N K; Alam, A K M M; Dafader, N C; Haque, M E; Akhtar, F; Ahmed, M U; Rashid, H; Begum, R

    2006-01-01

    Poly(vinyl alcohol) (PVA) can be modified to polymer hydrogels by radiation crosslinking and can be used in different biomedical applications. A study was done on the optimization of ingredients concentration for preparing good quality PVA hydrogels with natural polysaccharides. The synthesized hydrogels were also characterized by measuring the different physical properties e.g. gel fraction, swelling and absorption rate. Besides these, sterility test were also performed. Good quality hydrogels were obtained from PVA and natural polysaccharides solutions with 27 kGy radiation dose. There is an influence of natural polysaccharides on the gel fraction of hydrogel. The increase in the amount of polysaccharide causes a decrease in gel fraction that is decrease in the crosslinking density of PVA hydrogel network. The prepared hydrogels were found to be sterile.

  20. Thermoresponsive chitosan-agarose hydrogel for skin regeneration.

    Science.gov (United States)

    Miguel, Sónia P; Ribeiro, Maximiano P; Brancal, Hugo; Coutinho, Paula; Correia, Ilídio J

    2014-10-13

    Healing enhancement and pain control are critical issues on wound management. So far, different wound dressings have been developed. Among them, hydrogels are the most applied. Herein, a thermoresponsive hydrogel was produced using chitosan (deacetylation degree 95%) and agarose. Hydrogel bactericidal activity, biocompatibility, morphology, porosity and wettability were characterized by confocal microscopy, MTS assay and SEM. The performance of the hydrogel in the wound healing process was evaluated through in vivo assays, during 21 days. The attained results revealed that hydrogel has a pore size (90-400 μm) compatible with cellular internalization and proliferation. A bactericidal activity was observed for hydrogels containing more than 188 μg/mL of chitosan. The improved healing and the lack of a reactive or a granulomatous inflammatory reaction in skin lesions treated with hydrogel demonstrate its suitability to be used in a near future as a wound dressing.

  1. Antimicrobial hydrogels for the treatment of infection.

    Science.gov (United States)

    Veiga, Ana Salomé; Schneider, Joel P

    2013-11-01

    The increasing prevalence of microbial infections, especially those associated with impaired wound healing and biomedical implant failure has spurred the development of new materials having antimicrobial activity. Hydrogels are a class of highly hydrated material finding use in diverse medical applications such as drug delivery, tissue engineering, as wound fillers, and as implant coatings, to name a few. The biocompatible nature of many gels make them a convenient starting platform to develop selectively active antimicrobial materials. Hydrogels with antimicrobial properties can be obtained through the encapsulation or covalent immobilization of known antimicrobial agents, or the material itself can be designed to possess inherent antimicrobial activity. In this review we present an overview of antimicrobial hydrogels that have recently been developed and when possible provide a discussion relevant to their mechanism of action.

  2. Controlled Angiogenesis in Peptide Nanofiber Composite Hydrogels.

    Science.gov (United States)

    Wickremasinghe, Navindee C; Kumar, Vivek A; Shi, Siyu; Hartgerink, Jeffrey D

    2015-09-14

    Multidomain peptide (MDP) nanofibers create scaffolds that can present bioactive cues to promote biological responses. Orthogonal self-assembly of MDPs and growth-factor-loaded liposomes generate supramolecular composite hydrogels. These composites can act as delivery vehicles with time-controlled release. Here we examine the controlled release of placental growth factor-1 (PlGF-1) for its ability to induce angiogenic responses. PlGF-1 was loaded either in MDP matrices or within liposomes bound inside MDP matrices. Scaffolds showed expected rapid infiltration of macrophages. When released through liposomes incorporated in MDP gels (MDP(Lipo)), PlGF-1 modulates HUVEC VEGF receptor activation in vitro and robust vessel formation in vivo. These loaded MDP(Lipo) hydrogels induce a high level of growth-factor-mediated neovascular maturity. MDP(Lipo) hydrogels offer a biocompatible and injectable platform to tailor drug delivery and treat ischemic tissue diseases.

  3. Synthesis and characterization of anisotropic magnetic hydrogels

    Science.gov (United States)

    Hinrichs, Stephan; Nun, Nils; Fischer, Birgit

    2017-06-01

    Multiresponsive hydrogels are an interesting new class of materials. They offer the advantage, that they respond to different stimuli like temperature, pH and magnetic fields. By this they can change their properties which makes the hydrogels ideal candidates for many applications in the technical as well as medical field. Here we present the synthesis and characterization of hydrogels - micro- as well as macrogels - which consist of an iron oxide core, varying in phase and morphology, embedded in a thermoresponsive polymer, consisting of poly N-isopropylacrylamide. By using dynamic light scattering we investigated the thermoresponsive properties. In addition we were able to follow the formation of the macrogel by monitoring the shear viscosity.

  4. Blended Identities: Identity Work, Equity and Marginalization in Blended Learning

    Science.gov (United States)

    Heikoop, Will

    2013-01-01

    This article is a theoretical study of the self-presentation strategies employed by higher education students online; it examines student identity work via profile information and avatars in a blended learning environment delivered through social networking sites and virtual worlds. It argues that students are faced with difficult choices when…

  5. 7 CFR 989.16 - Blend.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Blend. 989.16 Section 989.16 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and... CALIFORNIA Order Regulating Handling Definitions § 989.16 Blend. Blend means to mix or commingle raisins. ...

  6. Radiation effects on LDPE/EVA blends

    Energy Technology Data Exchange (ETDEWEB)

    Sharif, Jamaliah; Aziz, S.H.S.A.Sharifah Hanisah Syed Abdul; Hashim, Kamaruddin

    2000-04-01

    The effect of radiation on the properties of low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) blends were investigated. The improvement of the measured gel content, thermal elongation, tensile strength, elongation at break and heat deformation of the blends have confirmed the positive effect of electron beam irradiation on the blends.

  7. 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.

  8. Injectable silk-polyethylene glycol hydrogels.

    Science.gov (United States)

    Wang, Xiaoqin; Partlow, Benjamin; Liu, Jian; Zheng, Zhaozhu; Su, Bo; Wang, Yansong; Kaplan, David L

    2015-01-01

    Silk hydrogels for tissue repair are usually pre-formed via chemical or physical treatments from silk solutions. For many medical applications, it is desirable to utilize injectable silk hydrogels at high concentrations (>8%) to avoid surgical implantation and to achieve slow in vivo degradation of the gel. In the present study, injectable silk solutions that formed hydrogels in situ were generated by mixing silk with low-molecular-weight polyethylene glycol (PEG), especially PEG300 and 400 (molecular weight 300 and 400g mol(-1)). Gelation time was dependent on the concentration and molecular weight of PEG. When the concentration of PEG in the gel reached 40-45%, gelation time was less than 30min, as revealed by measurements of optical density and rheological studies, with kinetics of PEG400 faster than PEG300. Gelation was accompanied by structural changes in silk, leading to the conversion from random coil in solution to crystalline β-sheets in the gels, based on circular dichroism, attenuated total reflection Fourier transform infrared spectroscopy and X-ray diffraction. The modulus (127.5kPa) and yield strength (11.5kPa) determined were comparable to those of sonication-induced hydrogels at the same concentrations of silk. The time-dependent injectability of 15% PEG-silk hydrogel through 27G needles showed a gradual increase of compression forces from ∼10 to 50N within 60min. The growth of human mesenchymal stem cells on the PEG-silk hydrogels was hindered, likely due to the presence of PEG, which grew after a 5 day delay, presumably while the PEG solubilized away from the gel. When 5% PEG-silk hydrogel was subcutaneously injected in rats, significant degradation and tissue in-growth took place after 20 days, as revealed by ultrasound imaging and histological analysis. No significant inflammation around the gel was observed. The features of injectability, slow degradation and low initial cell attachment suggests that these PEG-silk hydrogels are of interest

  9. Application of hydrogel system for neutron attenuation

    CERN Document Server

    Gupta, S C; Gupta, B P

    2000-01-01

    Hydrogel sheets based on poly(vinyl alcohol) (PVA) and poly(vinyl acetate) (PVAc) have been prepared by the technique of acetalization of PVA using formaldehyde and grafting of acrylic acid onto PVAc by gamma irradiation. PVA hydrogel (PVAB) sheets have been prepared in geometrically stable shapes by compression moulding process and characterised for their thermal properties, geometrical stability on water absorption, and neutron shielding efficiency. The effective protection from fast neutrons can be increased by a factor of 18% by swelling the PVAB sheets to 210% in water. The water intake and subsequent retention of water by the sheet can be tailored as per shielding requirements.

  10. Yield stress determines bioprintability of hydrogels based on gelatin-methacryloyl and gellan gum for cartilage bioprinting.

    Science.gov (United States)

    Mouser, Vivian H M; Melchels, Ferry P W; Visser, Jetze; Dhert, Wouter J A; Gawlitta, Debby; Malda, Jos

    2016-07-19

    Bioprinting of chondrocyte-laden hydrogels facilitates the fabrication of constructs with controlled organization and shape e.g. for articular cartilage implants. Gelatin-methacryloyl (gelMA) supplemented with gellan gum is a promising bio-ink. However, the rheological properties governing the printing process, and the influence of gellan gum on the mechanical properties and chondrogenesis of the blend, are still unknown. Here, we investigated the suitability of gelMA/gellan for cartilage bioprinting. Multiple concentrations, ranging from 3% to 20% gelMA with 0%-1.5% gellan gum, were evaluated for their printability, defined as the ability to form filaments and to incorporate cells at 15 °C-37 °C. To support the printability assessment, yield stress and viscosity of the hydrogels were measured. Stiffness of UV-cured constructs, as well as cartilage-like tissue formation by embedded chondrocytes, were determined in vitro. A large range of gelMA/gellan concentrations were printable with inclusion of cells and formed the bioprinting window. The addition of gellan gum improved filament deposition by inducing yielding behavior, increased construct stiffness and supported chondrogenesis. High gellan gum concentrations, however, did compromise cartilage matrix production and distribution, and even higher concentrations resulted in too high yield stresses to allow cell encapsulation. This study demonstrates the high potential of gelMA/gellan blends for cartilage bioprinting and identifies yield stress as a dominant factor for bioprintability.

  11. [Monograph for N-Methyl-pyrrolidone (NMP) and human biomonitoring values for the metabolites 5-Hydroxy-NMP and 2-Hydroxy-N-methylsuccinimide].

    Science.gov (United States)

    2015-10-01

    1-Methyl-pyrrolidone (NMP) is used as a solvent in many technical applications. The general population may be exposed to NMP from the use as ingredient in paint and graffiti remover, indoors also from use in paints and carpeting. Because of developmental toxic effects, the use of NMP in consumer products in the EU is regulated. The developmental effects accompanied by weak maternally toxic effects in animal experiments are considered as the critical effects by the German HBM Commission. Based on these effects, HBM-I values of 10 mg/l urine for children and of 15 mg/l for adults, respectively, were derived for the metabolites 5-Hydroxy-NMP and 2-Hydroxy-N-methylsuccinimide. HBM-II-values were set to 30 mg/l urine for children and 50 mg/l for adults, respectively. Because of similar effects of the structural analogue 1-ethyl-2-pyrrolidone (NEP), the possible mixed exposure to both compounds has to be taken into account when evaluating the total burden.

  12. Polysulfone hemodiafiltration membranes with enhanced anti-fouling and hemocompatibility modified by poly(vinyl pyrrolidone) via in situ cross-linked polymerization.

    Science.gov (United States)

    Zhu, Lijing; Song, Haiming; Wang, Jiarong; Xue, Lixin

    2017-05-01

    Poly(vinyl pyrrolidone) (PVP) and its copolymers have been widely employed for the modification of hemodiafiltration membranes due to their excellent hydrophilicity, antifouling and hemocompatibility. However, challenges still remain to simplify the modification procedure and to improve the utilization efficiency. In this paper, antifouling and hemocompatibility polysulfone (PSf) hemodiafiltration membranes were fabricated via in situ cross-linked polymerization of vinyl pyrrolidone (VP) and vinyltriethoxysilane (VTEOS) in PSf solutions and non-solvent induced phase separation (NIPS) technique. The prepared membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), which suggested that VP and VTEOS have been cross-linked copolymerized in PSf membranes. The modified PSf membranes with high polymer content showed improved hydrophilicity, ultrafiltration and protein antifouling ability. In addition, the modified PSf membranes showed lower protein adsorption, inhibited platelet adhesion and deformation, prolonged the activated partial thromboplastin time (APTT), prothrombin time (PT), and decreased the content of fibrinogen (FIB) transferring to fibrin, indicating enhanced hemocompatibility. In a word, the present work provides a simple and effective one-step modification method to construct PSf membranes with improved hydrophilicity, antifouling and hemocompatibility.

  13. pH-responsive hydrogel coated fiber Bragg grating-based chemo mechanical sensor bioreactor applications

    Science.gov (United States)

    Kishore, P. V. N.; Sai Shankar, M.

    2017-04-01

    This paper describes a fiber optics based pH sensor by using wavelength modulated techniques. Fiber Bragg grating (FBG) is functionalized with a stimulus responsive hydrogel which induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of Poly (vinyl alcohol)/Poly (acrylic acid). The induced strain results in a shift of FBG reflected peak which is monitored by an interrogator. The sensor system shows a good linearity in acidic pH range of 3 to 7 with a sensitivity of 12.16pm/pH. Besides that it shows good repeatability which proves it to be fit for pH sensing applications.

  14. Hydrogel-coated fiber Bragg grating sensor for pH monitoring

    Science.gov (United States)

    Pabbisetti, Vayu Nandana Kishore; Madhuvarasu, Sai Shankar

    2016-06-01

    We present a fiber-optic wavelength-modulated sensor for pH applications. Fiber Bragg grating (FBG) is functionalized with a stimulus-responsive hydrogel that induces a strain on FBG due to mechanical expansion of the gel in response to ambient pH changes. The gel is synthesized from the blends of poly (vinyl alcohol)/poly (acrylic acid). The induced strain results in a shift of FBG reflected peak that is monitored by an interrogator. The sensor system shows good linearity in the acidic pH range of 3 to 7 with a sensitivity of 12.16 pm/pH. In addition, it shows good repeatability and oscillator behavior, which proves it to be fit for pH sensing applications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun, YuWei; Zhou, Chao; Zhang, AoKai; Xu, LiQun; Yao, Fang [School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, Jiangsu Province, 211189 (China); Cen, Lian, E-mail: cenlian@hotmail.com [National Tissue Engineering Center of China, No.68, East Jiang Chuan Road, Shanghai, 200241 (China); School of Chemical Engineering, East China University of Science and Technology, No.130, Mei Long Road, Shanghai, 200237 (China); Fu, Guo-Dong, E-mail: fu7352@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, Jiangsu Province, 211189 (China)

    2014-11-30

    Highlights: • Many biological tissues are 3-dimensionally asymmetric in structure and properties, it would be desirable if hydrogels could bear such structural similarity with specialized surface and bulk properties. Moreover, gradual but continuous variation in spatial structural and property is also a common phenomenon in biological tissues, such as interfaces between bone and tendon, or between bone and cartilage. Hence, the development of a method to introduce well-defined functional polymer brushes on PEG hydrogels, especially with precisely controlled spatial structure in 3-dimensions, would impart the hydrogels with special functionalities and wider applications. Poly(ethylene glycol) (PEG) hydrogels with 3-dimensionally controlled well-defined poly(N-isopropylacrylamide) (poly(NIPAAm)) brushes were prepared by combined copper(I)-catalyzed azide-alkyne cycloaddition (“Click Chemistry”) and atom transfer radical polymerization (ATRP). The resulting hydrogels were presented as representatives with their detailed synthesis routes and characterization. H{sub PEG}-S-poly(NIPAAm) is a hydrogel with poly(NIPAAm) brushes mainly grafted on surface, whereas H{sub PEG}-G-poly(NIPAAm) has a gradiently decreased poly(NIPAAm) brushes in their chain length from surface to inside. On the other hand, poly(NIPAAm) brushes in H{sub PEG}-U-poly(NIPAAm) are uniformly dispersed throughout the whole hydrogel network. Successful preparation of H{sub PEG}-S-poly(NIPAAm), H{sub PEG}-G-poly(NIPAAm) and H{sub PEG}-U-poly(NIPAAm) were ascertained by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Hence, the flexibility and controllability of the synthetic strategy in varying the distribution of polymer brushes and hydrogel surface properties was demonstrated. Hydrogels with tunable and well-defined 3-dimensional poly(NIPAAm) polymer brushes could be tailor-designed to find potential applications in smart devices or skin dressing, such as for diabetics

  16. Amorphous polymeric binary blend pH-responsive nanoparticles for dissolution enhancement of antiviral drug

    Directory of Open Access Journals (Sweden)

    Deep R. Naik

    2016-09-01

    Full Text Available The aim of this study was to develop and optimize a nanoparticulate carrier based on polymeric blends of cellulose acetate butyrate (CAB and poly(vinyl pyrrolidone (PVP to enhance dissolution profile of an antiviral drug. These nanoparticles are studied by means of X-ray powder diffraction, FTIR and DSC while the morphology evaluated using SEM analysis. Drug-loaded nanoparticles were produced in spherical shape with sizes and encapsulation efficiency ranging from 322 to 434 nm and 50% to 70% respectively. The effects of different CAB/PVP ratios, concentration of drug and emulsifier on the nanoparticle size, drug encapsulation and in vitro release were studied in detail. In vitro release along with mechanism and kinetics were studied in different pHs indicating that the release of drug from nanoparticles was pH-responsive. All the nanoparticles displayed a slowed release pattern with the reduced burst release. The mechanism and kinetics of the drug delivery system was also systematically studied using various models such as zero order, first order, Higuchi model and Korsmeyer–Peppas. The results indicate that the new CAB/PVP nanoparticles have a promising potential to serve as an antiviral controlled delivery system.

  17. Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Nordiana; Ali, Ab Malik Marwan [Ionic Material and Devices Research Laboratory, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Lepit, Ajis; Rasmidi, Rosfayanti [Faculty of Applied Sciences, Universiti Teknologi MARA Sabah, Beg Berkunci 71, 88997 Kota Kinabalu (Malaysia); Subban, Ri Hanum Yahaya [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Yahya, Muhd Zu Azhan [Faculty of Defence Science & Technology, Universiti Pertahanan Nasional Malaysia, 57000 Kuala Lumpur (Malaysia)

    2015-08-28

    Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d{sub 6}) solution of the purified polymer using {sup 1}H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C, except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10{sup −3} Scm{sup −1} at 30°C and 3.383 × 10{sup −3} Scm{sup −1} at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.

  18. Netbaserede uddannelser og blended learning

    DEFF Research Database (Denmark)

    Bertelsen, Jesper Vedel; Vognsgaard Hjernø, Henriette; Jensen, Michael Peter

    2016-01-01

    Denne håndbog er tænkt som inspiration til uddannelsesfaglige medarbejdere, som er eller skal i gang med at undervise på en netbaseret uddannelse i UCL. Håndbogen giver et teoretisk overblik i forhold til netbaserede uddannelser, online- og blended learning samt en indførsel i hvilke didaktiske...

  19. Improvement of biodiesel methanol blends

    Directory of Open Access Journals (Sweden)

    Y. Datta Bharadwaz

    2016-06-01

    Full Text Available The main objective of this work was to improve the performance of biodiesel–methanol blends in a VCR engine by using optimized engine parameters. For optimization of the engine, operational parameters such as compression ratio, fuel blend, and load are taken as factors, whereas performance parameters such as brake thermal efficiency (Bth and brake specific fuel consumption (Bsfc and emission parameters such as carbon monoxide (CO, unburnt hydrocarbons (HC, Nitric oxides (NOx and smoke are taken as responses. Experimentation is carried out as per the design of experiments of the response surface methodology. Optimization of engine operational parameters is carried out using Derringers Desirability approach. From the results obtained it is inferred that the VCR engine has maximum performance and minimum emissions at 18 compression ratio, 5% fuel blend and at 9.03 kg of load. At this optimized operating conditions of the engine the responses such as brake thermal efficiency, brake specific fuel consumption, carbon monoxide, unburnt hydrocarbons, nitric oxide, and smoke are found to be 31.95%, 0.37 kg/kW h, 0.036%, 5 ppm, 531.23 ppm and 15.35% respectively. It is finally observed from the mathematical models and experimental data that biodiesel methanol blends have maximum efficiency and minimum emissions at optimized engine parameters.

  20. New Faces of Blended Learning

    Science.gov (United States)

    Horn, Michael B.; Fisher, Julia Freeland

    2017-01-01

    The Clayton Christiansen Institute maintains a database of more than 400 schools across the United States that have implemented some form of blended learning, which combines online learning with brick-and-mortar classrooms. Data the Institute has collected over the past six months suggests three trends as this model continues to evolve and mature.…

  1. Rapid 3D printing of anatomically accurate and mechanically heterogeneous aortic valve hydrogel scaffolds

    Science.gov (United States)

    Hockaday, L A; Kang, K H; Colangelo, N W; Cheung, P Y C; Duan, B; Malone, E; Wu, J; Girardi, L N; Bonassar, L J; Lipson, H; Chu, C C; Butcher, J T

    2013-01-01

    The aortic valve exhibits complex three-dimensional (3D) anatomy and heterogeneity essential for long-term efficient biomechanical function. These are, however, challenging to mimic in de novo engineered living tissue valve strategies. We present a novel simultaneous 3D-printing/photocrosslinking technique for rapidly engineering complex, heterogeneous aortic valve scaffolds. Native anatomic and axisymmetric aortic valve geometries (root wall and tri-leaflets) with 12 to 22 mm inner diameters (ID) were 3D printed with poly-ethylene glycol-diacrylate (PEG-DA) hydrogels (700 or 8000 MW) supplemented with alginate. 3D printing geometric accuracy was quantified and compared using Micro-CT. Porcine aortic valve interstitial cells (PAVIC) seeded scaffolds were cultured for up to 21 days. Results showed that blended PEG-DA scaffolds could achieve over 10-fold range in elastic modulus (5.3±0.9 to 74.6±1.5 kPa). 3D printing times for valve conduits with mechanically contrasting hydrogels were optimized to 14 to 45 minutes, increasing linearly with conduit diameter. Larger printed valves had greater shape fidelity (93.3±2.6, 85.1±2.0, and 73.3±5.2% for 22, 17, and 12 mm ID porcine valves; 89.1±4.0, 84.1±5.6, and 66.6±5.2% for simplified valves). PAVIC seeded scaffolds maintained near 100% viability over 21 days. These results demonstrate that 3D hydrogel printing with controlled photocrosslinking can rapidly fabricate anatomical heterogeneous valve conduits that support cell engraftment. PMID:22914604

  2. Hydrogel-forming microneedle arrays: Potential for use in minimally-invasive lithium monitoring.

    Science.gov (United States)

    Eltayib, Eyman; Brady, Aaron J; Caffarel-Salvador, Ester; Gonzalez-Vazquez, Patricia; Zaid Alkilani, Ahlam; McCarthy, Helen O; McElnay, James C; Donnelly, Ryan F

    2016-05-01

    We describe, for the first time, hydrogel-forming microneedle (s) (MN) arrays for minimally-invasive extraction and quantification of lithium in vitro and in vivo. MN arrays, prepared from aqueous blends of hydrolysed poly(methyl-vinylether-co-maleic anhydride) and crosslinked by poly(ethyleneglycol), imbibed interstitial fluid (ISF) upon skin insertion. Such MN were always removed intact. In vitro, mean detected lithium concentrations showed no significant difference following 30min MN application to excised neonatal porcine skin for lithium citrate concentrations of 0.9 and 2mmol/l. However, after 1h application, the mean lithium concentrations extracted were significantly different, being appropriately concentration-dependent. In vivo, rats were orally dosed with lithium citrate equivalent to 15mg/kg and 30mg/kg lithium carbonate, respectively. MN arrays were applied 1h after dosing and removed 1h later. The two groups, having received different doses, showed no significant difference between lithium concentrations in serum or MN. However, the higher dosed rats demonstrated a lithium concentration extracted from MN arrays equivalent to a mean increase of 22.5% compared to rats which received the lower dose. Hydrogel-forming MN clearly have potential as a minimally-invasive tool for lithium monitoring in outpatient settings. We will now focus on correlation between serum and MN lithium concentrations.

  3. Bioinspired, biomimetic, double-enzymatic mineralization of hydrogels for bone regeneration with calcium carbonate

    DEFF Research Database (Denmark)

    Lopez-Heredia, Marco A.; Łapa, Agata; Mendes, Ana Carina Loureiro

    2017-01-01

    Hydrogels are popular materials for tissue regeneration. Incorporation of biologically active substances, e.g. enzymes, is straightforward. Hydrogel mineralization is desirable for bone regeneration. Here, hydrogels of Gellan Gum (GG), a biocompatible polysaccharide, were mineralized biomimetical...

  4. Study on combustion characteristics of blended coals

    Energy Technology Data Exchange (ETDEWEB)

    Li Yonghua; Wang Chunbo; Chen Hongwei [North China Electric Power University, Baoding (China)

    2007-02-15

    Power plants in China have to burn blended coal instead of one specific coal for a variety of reasons. So it is of great necessity to investigate the combustion of blended coals. Using a test rig with a capacity of 640 MJ/h with an absolute milling system and flue gas online analysis system, characteristics such as burnout, slag, and pollution of some blended coals were investigated. The ratio of coke and slag as a method of distinguishing coal slagging characteristic was introduced. The results show that the blending of coal has some effect on NOx but there is no obvious rule. SOx emission can be reduced by blending low sulfur coal.

  5. Introducing blended e-learning course design

    DEFF Research Database (Denmark)

    Gyamfi, Samuel Adu; Ryberg, Thomas

    2012-01-01

    In the face of diminishing education budgets in higher education, blended learning has been found to be a viable and effective approach to deliver high-quality, up-to-date, on-demand solutions to developing cross-curricular skills of undergraduates. However, research has also shown that blended...... learning solutions do not often live up to the potential of the approach or fail to produce the intended results because the students are not always equipped to handle the technical, psychological and organisational challenges of blended learning approaches. This project surveyed seventy-five first year...... the students’ e-readiness for an implementation of a blend-ed course design....

  6. Introducing blended e-learning course design

    DEFF Research Database (Denmark)

    Gyamfi, Samuel Adu; Ryberg, Thomas

    2012-01-01

    In the face of diminishing education budgets in higher education, blended learning has been found to be a viable and effective approach to deliver high-quality, up-to-date, on-demand solutions to developing cross-curricular skills of undergraduates. However, research has also shown that blended...... learning solutions do not often live up to the potential of the approach or fail to produce the intended results because the students are not always equipped to handle the technical, psychological and organisational challenges of blended learning approaches. This project surveyed seventy-five first year...... the students’ e-readiness for an implementation of a blend-ed course design....

  7. 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.

  8. Enhancement of Curcumin Bioavailability Using Nanocellulose Reinforced Chitosan Hydrogel

    Directory of Open Access Journals (Sweden)

    Thennakoon M. Sampath Udeni Gunathilake

    2017-02-01

    Full Text Available A unique biodegradable, superporous, swellable and pH sensitive nanocellulose reinforced chitosan hydrogel with dynamic mechanical properties was prepared for oral administration of curcumin. Curcumin, a less water-soluble drug was used due to the fact that the fast swellable, superporous hydrogel could release a water-insoluble drug to a great extent. CO2 gas foaming was used to fabricate hydrogel as it eradicates using organic solvents. Field emission scanning electron microscope images revealed that the pore size significantly increased with the formation of widely interconnected porous structure in gas foamed hydrogels. The maximum compression of pure chitosan hydrogel was 25.9 ± 1 kPa and it increased to 38.4 ± 1 kPa with the introduction of 0.5% cellulose nanocrystals. In vitro degradation of hydrogels was found dependent on the swelling ratio and the amount of CNC of the hydrogel. All the hydrogels showed maximum swelling ratios greater than 300%. The 0.5% CNC-chitosan hydrogel showed the highest swelling ratio of 438% ± 11%. FTIR spectrum indicated that there is no interaction between drug and ingredients present in hydrogels. The drug release occurred in non-Fickian (anomalous manner in simulated gastric medium. The drug release profiles of hydrogels are consistent with the data obtained from the swelling studies. After gas foaming of the hydrogel, the drug loading efficiency increased from 41% ± 2.4% to 50% ± 2.0% and release increased from 0.74 to 1.06 mg/L. The drug release data showed good fitting to Ritger-Peppas model. Moreover, the results revealed that the drug maintained its chemical activity after in vitro release. According to the results of this study, CNC reinforced chitosan hydrogel can be suggested to improve the bioavailability of curcumin for the absorption from stomach and upper intestinal tract.

  9. Polyacrylamide Hydrogel Properties for Horticultural Applications

    Science.gov (United States)

    Polyacrylamide (PAAm) hydrogels are commonly employed to ensure hydration of the growth media and minimize crop losses during the crop production and postproduction phases in horticulture. However, studies of the effect of these materials have shown that they have a minimal effect on crop life and q...

  10. 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)

  11. Transparent hydrogel with enhanced water retention capacity by introducing highly hydratable salt

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yuanyuan; Xiang, Feng; Wang, Hong, E-mail: hwang@mail.xjtu.edu.cn, E-mail: suo@seas.harvard.edu [Electronic Materials Research Laboratory, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Baohong; Zhou, Jinxiong [State Key Laboratory for Strength and Vibration of Mechanical Structures, International Center for Applied Mechanics and School of Aerospace, Xi' an Jiaotong University, Xi' an 710049 (China); Suo, Zhigang, E-mail: hwang@mail.xjtu.edu.cn, E-mail: suo@seas.harvard.edu [School of Engineering and Applied Sciences, Kavli Institute of Bionano Science and Technology, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2014-10-13

    Polyacrylamide hydrogels containing salt as electrolyte have been used as highly stretchable transparent electrodes in flexible electronics, but those hydrogels are easy to dry out due to water evaporation. Targeted, we try to enhance water retention capacity of polyacrylamide hydrogel by introducing highly hydratable salts into the hydrogel. These hydrogels show enhanced water retention capacity in different level. Specially, polyacrylamide hydrogel containing high content of lithium chloride can retain over 70% of its initial water even in environment with relative humidity of only 10% RH. The excellent water retention capacities of these hydrogels will make more applications of hydrogels become possible.

  12. CARBONYL STRETCHING FREQUENCY-CHARACTERISTICS FOR THE STRONGLY HYDROPHOBIC SOLUTE, N-CYCLOHEXYL-2-PYRROLIDONE IN BINARY AQUEOUS MIXTURES AT 298.15-K - EVIDENCE FOR A 2-DOMAIN MODEL FOR 2-BUTOXYETHANOL WATER MIXTURES

    NARCIS (Netherlands)

    ENGBERTS, JBFN; PERJESSY, A; BLANDAMER, MJ; EATON, G

    1992-01-01

    Infrared spectra are reported in the C=O stretching region for N-cyclohexyl-2-pyrrolidone (NCP) in D2O as a function of the mole fraction of added cosolvents. As the solvent composition is changed by adding methanol, ethanol and 2-methylpropan-2-ol, the spectra reveal the presence of two types of hy

  13. Versatile Molding Process for Tough Cellulose Hydrogel Materials.

    Science.gov (United States)

    Kimura, Mutsumi; Shinohara, Yoshie; Takizawa, Junko; Ren, Sixiao; Sagisaka, Kento; Lin, Yudeng; Hattori, Yoshiyuki; Hinestroza, Juan P

    2015-11-05

    Shape-persistent and tough cellulose hydrogels were fabricated by a stepwise solvent exchange from a homogeneous ionic liquid solution of cellulose exposure to methanol vapor. The cellulose hydrogels maintain their shapes under changing temperature, pH, and solvents. The micrometer-scale patterns on the mold were precisely transferred onto the surface of cellulose hydrogels. We also succeeded in the spinning of cellulose hydrogel fibers through a dry jet-wet spinning process. The mechanical property of regenerated cellulose fibers improved by the drawing of cellulose hydrogel fibers during the spinning process. This approach for the fabrication of tough cellulose hydrogels is a major advance in the fabrication of cellulose-based structures with defined shapes.

  14. Antimicrobial Activity of Chitosan-Carbon Nanotube Hydrogels

    Directory of Open Access Journals (Sweden)

    Jayachandran Venkatesan

    2014-05-01

    Full Text Available In the present study, we have prepared chitosan-carbon nanotube (Chitosan-CNT hydrogels by the freeze-lyophilization method and examined their antimicrobial activity. Different concentrations of CNT were used in the preparation of Chitosan-CNT hydrogels. These differently concentrated CNT hydrogels were chemically characterized using Fourier Transform-Infrared Spectroscopy, Scanning Electron Microscopy and Optical microscopy. The porosity of the hydrogels were found to be >94%. Dispersion of chitosan was observed in the CNT matrix by normal photography and optical microscopy. The addition of CNT in the composite scaffold significantly reduced the water uptake ability. In order to evaluate antimicrobial activity, the serial dilution method was used towards Staphylococcus aureus, Escherichia coli and Candida tropicalis. The composite Chitosan-CNT hydrogel showed greater antimicrobial activity with increasing CNT concentration, suggesting that Chitosan-CNT hydrogel scaffold will be a promising biomaterial in biomedical applications.

  15. Comparison of Pectin Hydrogel Collection Methods in Microfluidic Device

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chaeyeon; Park, Ki-Su; Kang, Sung-Min; Kim, Jongmin; Song, YoungShin; Lee, Chang-Soo [Chungnam National University, Daejeon (Korea, Republic of)

    2015-12-15

    This study investigated the effect of different collection methods on physical properties of pectin hydrogels in microfluidic synthetic approach. The pectin hydrogels were simply produced by the incorporation of calcium ions dissolved in continuous mineral oil. Then, different collection methods, pipetting, tubing, and settling, for harvesting pectin hydrogels were applied. The settling method showed most uniform and monodispersed hydrogels. In the case of settling, a coefficient of variation was 3.46 which was lower than pipetting method (18.60) and tubing method (14.76). Under the settling method, we could control the size of hydrogels, ranging from 30 μm to 180 μm, by simple manipulation of the viscosity of pectin and volumetric flow rate of dispersed and continuous phase. Finally, according to the characteristics of simple encapsulation of biological materials, we envision that the pectin hydrogels can be applied to drug delivery, food, and biocompatible materials.

  16. 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.

  17. Swelling Behaviors of Polyaniline-Poly(Acrylic Acid) Hydrogels

    Institute of Scientific and Technical Information of China (English)

    ZHANG You-wei; ZHAO Jiong-xin; LI Xiao-feng; TAO Yong; WU Cheng-xun

    2005-01-01

    Using poly(acrylic acid) (PAA) aqueous solution, NaOH aqueous solution, aniline(An) and ammonim persulfate(APS), PAn-PAA hydrogels with a semi-interpenetrating structure connected by physical interlocks, chemical ion bonds and hydrogen bonds wcre prepared. The swelling properties of the hydrogels in solutions of different pH values(adjusted by adding NaOH or HCl) were studied. All the hydrogels prepared have similar swelling curves (the curves of equilibrium swelling ratio vs. pH value) and reach their maximum swelling at pH of 8 - 10. The maximum swelling ratio of the hydrogels is dependent on composition, including molecular weight of PAA, polymer content of the hydrogel,and molar ratios of AA to An, APS to An, and NaOH to AA.And the compositional dependence of the swelling capacity of PAn-PAA hydrogels was also studied.

  18. Stimuli-responsive hydrogels in drug delivery and tissue engineering.

    Science.gov (United States)

    Sood, Nikhil; Bhardwaj, Ankur; Mehta, Shuchi; Mehta, Abhinav

    2016-01-01

    Hydrogels are the three-dimensional network structures obtained from a class of synthetic or natural polymers which can absorb and retain a significant amount of water. Hydrogels are one of the most studied classes of polymer-based controlled drug release. These have attracted considerable attention in biochemical and biomedical fields because of their characteristics, such as swelling in aqueous medium, biocompatibility, pH and temperature sensitivity or sensitivity towards other stimuli, which can be utilized for their controlled zero-order release. The hydrogels are expected to explore new generation of self-regulated delivery system having a wide array of desirable properties. This review highlights the exciting opportunities and challenges in the area of hydrogels. Here, we review different literatures on stimuli-sensitive hydrogels, such as role of temperature, electric potential, pH and ionic strength to control the release of drug from hydrogels.

  19. Dielectric properties of Rhodamine-B and metal doped hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Okutan, M. [Department of Physics, Yıldız Technical University, 34210 Istanbul (Turkey); Coşkun, R. [Department of Chemistry, Bozok University, 66100 Yozgat (Turkey); Öztürk, M. [Institute of Science, Niğde University, 51240 Niğde (Turkey); Yalçın, O., E-mail: o.yalcin@nigde.edu.tr [Department of Physics, Niğde University, 51240 Niğde (Turkey)

    2015-01-15

    The electric and dielectric properties of Rhodamine-B (RB) and metal ions (Ag{sup +}, Co{sup 2+}, Cr{sup 3+}, Mn{sup 2+} and Ni{sup 2+}) doped hydrogels have been analyzed in an extended frequency range by impedance spectroscopy. The RB doped hydrogels has been found to be sensitive to ionic conduction and electrode polarization according to the metal doped hydrogels. We have shown that the ionic conductive of RB doped hydrogels is originated from the free ions motion within the doped hydrogels at high frequency. We have also taken into account the Cl{sup −} and N{sup +} ions in the structure of RB provide additional ionic contribution to RB doped hydrogels.

  20. 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

  1. SCATTERING FUNCTION OF POLYMER BLENDS

    Institute of Scientific and Technical Information of China (English)

    Lin-ping Ke; Mei-li Guo; De-lu Zhao

    2004-01-01

    For a system of flexible polymer molecules, the concepts of two concentrations, namely the segmental and the molecular concentrations, have been proposed in this paper. The former is equivalent to the volume fraction. The latter can be defined as the number of the gravity centers of macromolecules in a unit volume. The two concentrations should be correlated with each other by the conformational function of the polymer chain and should be discussed in different thermodynamic equations. On the basis of these concepts it has been proved that the Flory-Huggins entropy of mixing should be the result of the mixing "ideal gases of the gravity centers of macromolecules". The general correlation between the free energy of mixing and the scattering function (structural factor) of polymer blends has been studied based on the general fluctuation theory. When the Flory-Huggins free energy of mixing is adopted, the de Gennes scattering function of a polymer blend can be derived.

  2. Evaporation characteristics of ETBE-blended gasoline.

    Science.gov (United States)

    Okamoto, Katsuhiro; Hiramatsu, Muneyuki; Hino, Tomonori; Otake, Takuma; Okamoto, Takashi; Miyamoto, Hiroki; Honma, Masakatsu; Watanabe, Norimichi

    2015-04-28

    To reduce greenhouse gas emissions, which contribute to global warming, production of gasoline blended with ethyl tert-buthyl ether (ETBE) is increasing annually. The flash point of ETBE is higher than that of gasoline, and blending ETBE into gasoline will change the flash point and the vapor pressure. Therefore, it is expected that the fire hazard caused by ETBE-blended gasoline would differ from that caused by normal gasoline. The aim of this study was to acquire the knowledge required for estimating the fire hazard of ETBE-blended gasoline. Supposing that ETBE-blended gasoline was a two-component mixture of gasoline and ETBE, we developed a prediction model that describes the vapor pressure and flash point of ETBE-blended gasoline in an arbitrary ETBE blending ratio. We chose 8-component hydrocarbon mixture as a model gasoline, and defined the relation between molar mass of gasoline and mass loss fraction. We measured the changes in the vapor pressure and flash point of gasoline by blending ETBE and evaporation, and compared the predicted values with the measured values in order to verify the prediction model. The calculated values of vapor pressures and flash points corresponded well to the measured values. Thus, we confirmed that the change in the evaporation characteristics of ETBE-blended gasoline by evaporation could be predicted by the proposed model. Furthermore, the vapor pressure constants of ETBE-blended gasoline were obtained by the model, and then the distillation curves were developed.

  3. Photochemical Patterning of Ionically Cross-Linked Hydrogels

    Directory of Open Access Journals (Sweden)

    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.

  4. 4D Printing with Mechanically Robust, Thermally Actuating Hydrogels.

    Science.gov (United States)

    Bakarich, Shannon E; Gorkin, Robert; in het Panhuis, Marc; Spinks, Geoffrey M

    2015-06-01

    A smart valve is created by 4D printing of hydrogels that are both mechanically robust and thermally actuating. The printed hydrogels are made up of an interpenetrating network of alginate and poly(N-isopropylacrylamide). 4D structures are created by printing the "dynamic" hydrogel ink alongside other static materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Responsive Hydrogels for Label-Free Signal Transduction within Biosensors

    Directory of Open Access Journals (Sweden)

    Kamila Gawel

    2010-04-01

    Full Text Available Hydrogels have found wide application in biosensors due to their versatile nature. This family of materials is applied in biosensing either to increase the loading capacity compared to two-dimensional surfaces, or to support biospecific hydrogel swelling occurring subsequent to specific recognition of an analyte. This review focuses on various principles underpinning the design of biospecific hydrogels acting through various molecular mechanisms in transducing the recognition event of label-free analytes. Towards this end, we describe several promising hydrogel systems that when combined with the appropriate readout platform and quantitative approach could lead to future real-life applications.

  6. Tough and tunable adhesion of hydrogels: experiments and models

    Science.gov (United States)

    Zhang, Teng; Yuk, Hyunwoo; Lin, Shaoting; Parada, German A.; Zhao, Xuanhe

    2017-06-01

    As polymer networks infiltrated with water, hydrogels are major constituents of animal and plant bodies and have diverse engineering applications. While natural hydrogels can robustly adhere to other biological materials, such as bonding of tendons and cartilage on bones and adhesive plaques of mussels, it is challenging to achieve such tough adhesions between synthetic hydrogels and engineering materials. Recent experiments show that chemically anchoring long-chain polymer networks of tough synthetic hydrogels on solid surfaces create adhesions tougher than their natural counterparts, but the underlying mechanism has not been well understood. It is also challenging to tune systematically the adhesion of hydrogels on solids. Here, we provide a quantitative understanding of the mechanism for tough adhesions of hydrogels on solid materials via a combination of experiments, theory, and numerical simulations. Using a coupled cohesive-zone and Mullins-effect model validated by experiments, we reveal the interplays of intrinsic work of adhesion, interfacial strength, and energy dissipation in bulk hydrogels in order to achieve tough adhesions. We further show that hydrogel adhesion can be systematically tuned by tailoring the hydrogel geometry and silanization time of solid substrates, corresponding to the control of energy dissipation zone and intrinsic work of adhesion, respectively. The current work further provides a theoretical foundation for rational design of future biocompatible and underwater adhesives.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

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

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

    Directory of Open Access Journals (Sweden)

    L.B. Sukhodub

    2016-03-01

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

  9. Thermo-Responsive Hydrogels for Stimuli-Responsive Membranes

    Directory of Open Access Journals (Sweden)

    Evan Mah

    2013-09-01

    Full Text Available Composite membranes with stimuli-responsive properties can be made by coating a thermo-responsive hydrogel onto a micro- or macroporous support. These hydrogels undergo a temperature induced volume-phase transition, which contributes towards the composite membrane’s stimuli-responsive properties. This paper reviews research done on complimentary forms of temperature responsive “thermophilic” hydrogels, those exhibiting positive volume-phase transitions in aqueous solvent. The influences of intermolecular forces on the mechanism of phase-transition are discussed along with case examples of typical thermophilic hydrogels.

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

    Science.gov (United States)

    Moghadam, Mohamadreza Nassajian; Pioletti, Dominique P

    2016-08-01

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

  11. Force-compensated hydrogel-based pH sensor

    Science.gov (United States)

    Deng, Kangfa; Gerlach, Gerald; Guenther, Margarita

    2015-04-01

    This paper presents the design, simulation, assembly and testing of a force-compensated hydrogel-based pH sensor. In the conventional deflection method, a piezoresistive pressure sensor is used as a chemical-mechanical-electronic transducer to measure the volume change of a pH-sensitive hydrogel. In this compensation method, the pH-sensitive hydrogel keeps its volume constant during the whole measuring process, independent of applied pH value. In order to maintain a balanced state, an additional thermal actuator is integrated into the close-loop sensor system with higher precision and faster dynamic response. Poly (N-isopropylacrylamide) (PNIPAAm) with 5 mol% monomer 3-acrylamido propionic acid (AAmPA) is used as the temperature-sensitive hydrogel, while poly (vinyl alcohol) with poly (acrylic acid) (PAA) serves as the pH-sensitive hydrogel. A thermal simulation is introduced to assess the temperature distribution of the whole microsystem, especially the temperature influence on both hydrogels. Following tests are detailed to verify the working functions of a sensor based on pH-sensitive hydrogel and an actuator based on temperature-sensitive hydrogel. A miniaturized prototype is assembled and investigated in deionized water: the response time amounts to about 25 min, just half of that one of a sensor based on the conventional deflection method. The results confirm the applicability of t he compensation method to the hydrogel-based sensors.

  12. 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.

  13. Bragg grating chemical sensor with hydrogel as sensitive element

    Institute of Scientific and Technical Information of China (English)

    Xiaomei Liu(刘小梅); Shilie Zheng(郑史烈); Xianmin Zhang(章献民); Jun Cong(丛军); Kangsheng Chen(陈抗生); Jian Xu(徐坚)

    2004-01-01

    A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.

  14. Tumor Growth Suppression Induced by Biomimetic Silk Fibroin Hydrogels

    Science.gov (United States)

    Yan, Le-Ping; Silva-Correia, Joana; Ribeiro, Viviana P.; Miranda-Gonçalves, Vera; Correia, Cristina; da Silva Morais, Alain; Sousa, Rui A.; Reis, Rui M.; Oliveira, Ana L.; Oliveira, Joaquim M.; Reis, Rui L.

    2016-08-01

    Protein-based hydrogels with distinct conformations which enable encapsulation or differentiation of cells are of great interest in 3D cancer research models. Conformational changes may cause macroscopic shifts in the hydrogels, allowing for its use as biosensors and drug carriers. In depth knowledge on how 3D conformational changes in proteins may affect cell fate and tumor formation is required. Thus, this study reports an enzymatically crosslinked silk fibroin (SF) hydrogel system that can undergo intrinsic conformation changes from random coil to β-sheet conformation. In random coil status, the SF hydrogels are transparent, elastic, and present ionic strength and pH stimuli-responses. The random coil hydrogels become β-sheet conformation after 10 days in vitro incubation and 14 days in vivo subcutaneous implantation in rat. When encapsulated with ATDC-5 cells, the random coil SF hydrogel promotes cell survival up to 7 days, whereas the subsequent β-sheet transition induces cell apoptosis in vitro. HeLa cells are further incorporated in SF hydrogels and the constructs are investigated in vitro and in an in vivo chick chorioallantoic membrane model for tumor formation. In vivo, Angiogenesis and tumor formation are suppressed in SF hydrogels. Therefore, these hydrogels provide new insights for cancer research and uses of biomaterials.

  15. Development and characterization of a novel hydrogel adhesive for soft tissue applications

    Science.gov (United States)

    Sanders, Lindsey Kennedy

    With laparoscopic and robotic surgical techniques advancing, the need for an injectable surgical adhesive is growing. To be effective, surgical adhesives for internal organs require bulk strength and compliance to avoid rips and tears, and adhesive strength to avoid leakage at the application site, while not hindering the natural healing process. Although a number of tissue adhesives and sealants approved by the FDA for surgical use are currently available, attaining a useful balance in all of these qualities has proven difficult, particularly when considering applications involving highly expandable tissue, such as bladder and lung. The long-term goal of this project is to develop a hydrogel-based tissue adhesive that provides proper mechanical properties to eliminate the need for sutures in various soft tissue applications. Tetronic (BASF), a 4-arm poly(propylene oxide)-poly(ethylene oxide) (PPO-PEO) block copolymer, has been selected as the base material for the adhesive hydrogel system. Solutions of Tetronic T1107 can support reverse thermal gelation at physiological temperatures, which can be combined with covalent crosslinking to achieve a "tandem gelation" process making it ideal for use as a tissue adhesive. The objective of this doctoral thesis research is to improve the performance of the hydrogel based tissue adhesive developed previously by Cho and co-workers by applying a multi-functionalization of Tetronic. Specifically, this research aimed to improve bonding strength of Tetronic tissue adhesive using bi-functional modification, incorporate hemostatic function to the bi-functional Tetronic hydrogel, and evaluate the safety of bi-functional Tetronic tissue adhesive both in vitro and in vivo. In summary, we have developed a fast-curing, mechanically strong hemostatic tissue adhesive that can control blood loss in wet conditions during wound treatment applications (bladder, liver and muscle). Specifically, the bi-functional Tetronic adhesive (TAS) with a

  16. Simultaneous radiation induced graft polymerization of N-vinyl-2-pyrrolidone onto polypropylene non-woven fabric for improvement of blood compatibility

    Science.gov (United States)

    Li, Rong; Wang, Hengdong; Wang, Wenfeng; Ye, Yin

    2013-07-01

    In this study, N-vinyl-2-pyrrolidone (NVP) was grafted onto polypropylene non-woven fabric (PPNWF) through a simultaneous irradiation induced graft polymerization technique. Effect of the parameters of graft polymerization, i.e., monomer concentration, absorbed dose and dose rate, on the degree of grafting (DG) was investigated. The graft polymerization of NVP was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). A contact angle goniometry was used to test water contact angle (WCA) of original PPNWF and modified samples. The in vitro blood compatibility, including hemolysis, protein adsorption, platelet adhesion and activated partial thromboplastin time (APTT) of tested specimens, was evaluated. The results demonstrated that the hemocompatibility of PPNWF was improved via graft polymerization of NVP.

  17. Synthesis and characterization of mesoporous poly(N-vinyl-2-pyrrolidone) containing palladium nanoparticles as a novel heterogeneous organocatalyst for Heck reaction

    Science.gov (United States)

    Kalbasi, Roozbeh Javad; Negahdari, Meysam

    2014-04-01

    Mesoporous poly(N-vinyl-2-pyrrolidone) (MPVP) was prepared through a nanocasting technique based on mesoporous silica KIT-6 as sacrificial templates, and served as an efficient scaffold for supporting Pd nanoparticles. The physical and chemical properties of Pd-MPVP were characterized using FT-IR, XRD, BET, DRS UV-Vis, SEM, TEM and TGA techniques. The application of this novel purely organic heterogeneous catalyst, which combine the advantage of organic polymers and mesoporous materials, was investigated for Csbnd C bond formation through the Heck coupling reaction of aryl iodides, bromides and chlorides with styrene. It was observed that the activity of this catalyst decreased just 5% after nine regeneration processes were performed. This unique result opens new perspectives for application of purely organic mesoporous polymers as structurally defined hydrophobic catalyst in catalytic reactions.

  18. 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)

  19. Game innovation through conceptual blending

    DEFF Research Database (Denmark)

    Möring, Sebastian Martin

    In  this  paper  I  wish  to  apply implications of  the  Conceptual  Blending  Theory  to  computer  games.  I  will  analyze  chosen  examples  and  discuss  them  as  a  result  of  video  game  innovation  made  possible  through  "conceptual  blending."  Conceptual  blending  links  at  least......  integration  network  consisting  of  at  least  two  input  spaces,  a  generic  space  and  a  blended  space  as  well  as  its  governing  principles  consisting  of  composition,  completion,  and  elaboration.  With  the  help  of  these  instruments  I  analyze computer  games like  Tuper  Tario  Tros.......,  Hell.  The  purpose  of  my  approach  is  not  so  much  to  validate  the  ideas  of  conceptual  blending  theory  through  another  field  of  examples  (computer  games)  but  to  name  and analyze characteristics of the mentioned games with the  help of a given method....

  20. Game innovation through conceptual blending

    DEFF Research Database (Denmark)

    Möring, Sebastian Martin

    In  this  paper  I  wish  to  apply implications of  the  Conceptual  Blending  Theory  to  computer  games.  I  will  analyze  chosen  examples  and  discuss  them  as  a  result  of  video  game  innovation  made  possible  through  "conceptual  blending."  Conceptual  blending  links  at  least.......,  Hell.  The  purpose  of  my  approach  is  not  so  much  to  validate  the  ideas  of  conceptual  blending  theory  through  another  field  of  examples  (computer  games)  but  to  name  and analyze characteristics of the mentioned games with the  help of a given method.......  integration  network  consisting  of  at  least  two  input  spaces,  a  generic  space  and  a  blended  space  as  well  as  its  governing  principles  consisting  of  composition,  completion,  and  elaboration.  With  the  help  of  these  instruments  I  analyze computer  games like  Tuper  Tario  Tros...

  1. Correspondence Theory and Phonological Blending in French

    Directory of Open Access Journals (Sweden)

    Lee Scott

    2014-07-01

    Full Text Available Though less productive than rival word-formation processes like compounding and affixation, blending is still a rich source of neologisms in French. Despite this productivity, however, blends are often seen by scholars as unpredictable, uninteresting, or both. This analysis picks up where recent studies of blending have left off, using Correspondence Theory and a bundle of segmental constraints to deal with this phenomenon as it pertains to French. More specifically, it shows that blending is the result of a single output standing in correspondence with two or more other outputs, and that we do not need to refer to prosodic information, which is crucial in accounts of blending in languages with lexical stress like English, to account for the process in French. The analysis also differs from previous studies in that it locates blending exclusively within the phonology, leaving its morphological and semantic characteristics to be handled by other processes in the grammar.

  2. Evaporation characteristics of ETBE-blended gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Katsuhiro, E-mail: okamoto@nrips.go.jp [National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882 (Japan); Hiramatsu, Muneyuki [Yamanashi Prefectural Police H.Q., 312-4 Kubonakajima, Isawa-cho, Usui, Yamanashi 406-0036 (Japan); Hino, Tomonori; Otake, Takuma [Metropolitan Police Department, 2-1-1 Kasumigaseki, Chiyoda-ku, Tokyo 100-8929 (Japan); Okamoto, Takashi; Miyamoto, Hiroki; Honma, Masakatsu; Watanabe, Norimichi [National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882 (Japan)

    2015-04-28

    Highlights: • We chose 8-component hydrocarbon mixture as a model gasoline, and defined the molar mass of gasoline. • We proposed an evaporation model assuming a 2-component mixture of gasoline and ETBE. • We predicted the change in the vapor pressure of ETBE-blended gasoline by evaporation. • The vapor pressures were measured and compared as a means of verifying the model. • We presented the method for predicting flash points of the ETBE-blended gasoline. - Abstract: To reduce greenhouse gas emissions, which contribute to global warming, production of gasoline blended with ethyl tert-buthyl ether (ETBE) is increasing annually. The flash point of ETBE is higher than that of gasoline, and blending ETBE into gasoline will change the flash point and the vapor pressure. Therefore, it is expected that the fire hazard caused by ETBE-blended gasoline would differ from that caused by normal gasoline. The aim of this study was to acquire the knowledge required for estimating the fire hazard of ETBE-blended gasoline. Supposing that ETBE-blended gasoline was a two-component mixture of gasoline and ETBE, we developed a prediction model that describes the vapor pressure and flash point of ETBE-blended gasoline in an arbitrary ETBE blending ratio. We chose 8-component hydrocarbon mixture as a model gasoline, and defined the relation between molar mass of gasoline and mass loss fraction. We measured the changes in the vapor pressure and flash point of gasoline by blending ETBE and evaporation, and compared the predicted values with the measured values in order to verify the prediction model. The calculated values of vapor pressures and flash points corresponded well to the measured values. Thus, we confirmed that the change in the evaporation characteristics of ETBE-blended gasoline by evaporation could be predicted by the proposed model. Furthermore, the vapor pressure constants of ETBE-blended gasoline were obtained by the model, and then the distillation curves were

  3. Low frequency dielectric relaxation processes and ionic conductivity of montmorillonite clay nanoparticles colloidal suspension in poly(vinyl pyrrolidone−ethylene glycol blends

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available The dielectric dispersion behaviour of montmorillonite (MMT clay nanoparticles colloidal suspension in poly(vinyl pyrrolidone-ethylene glycol (PVP-EG blends were investigated over the frequency range 20 Hz to 1 MHz at 30°C. The 0, 1, 2, 3, 5 and 10 wt% MMT clay concentration of the weight of total solute (MMT+PVP were prepared in PVP-EG blends using EG as solvent. The complex relative dielectric function, alternating current (ac electrical conductivity, electric modulus and impedance spectra of these materials show the relaxation processes corresponding to the micro-Brownian motion of PVP chain, ion conduction and electrode polarization phenomena. The real part of ac conductivity spectra of these materials obeys Jonscher power law σ′(ω =σdc + Aωn in upper frequency end of the measurement, whereas dispersion in lower frequency end confirms the presence of electrode polarization effect. It was observed that the increase of clay concentration in the PVP-EG blends significantly increases the ac conductivity values, and simultaneously reduces the ionic conductivity relaxation time and electric double layer relaxation time, which suggests that PVP segmental dynamics and ionic motion are strongly coupled. The intercalation of EG structures in clay galleries and exfoliation of clay sheets by adsorption of PVP-EG structures on clay surfaces are discussed by considering the hydrogen bonding interactions between the hydroxyl group (–OH of EG molecules, carbonyl group (C=O of PVP monomer units, and the hydroxylated aluminate surfaces of the MMT clay particles. Results suggest that the colloidal suspension of MMT clay nano particles in the PVP-EG blends provide a convenient way to obtain an electrolyte solution with tailored electrical conduction properties.

  4. THE COMBUSTION CHARACTERISTICS OF LIGNITE BLENDS

    Institute of Scientific and Technical Information of China (English)

    Cheng Jun; Zhou Junhu; Cao Xinyu; Cen Kefa

    2000-01-01

    The combustion characteristics of lignite blends were studied with a thermogravimetric analyzer (t.g.a.), at constant heating rate.The characteristic temperatures were determined from the burning profiles.It was found that the characteristic times of combustion reaction moved forward, the ignition temperature dropped and the burnout efficiency slightly changed when blending lignites.The characteristic parameters of blends could not be predicted as a linear function of the average values of the individual lignites.when blending with less reactive coal, the ignition and burnout characteristics of lignite turned worse.

  5. Synthesis and characterization of injectable bioadhesive hydrogels for nucleus pulposus replacement and repair of the damaged intervertebral disc.

    Science.gov (United States)

    Vernengo, J; Fussell, G W; Smith, N G; Lowman, A M

    2010-05-01

    Bioadhesive polymers are natural or synthetic materials that can be used for soft tissue repair. The aim of this investigation was to develop an injectable, bioadhesive hydrogel with the potential to serve as a synthetic replacement for the nucleus pulposus of the intervertebral disc or as an annulus closure material. Branched copolymers of poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (PEG) were blended with poly(ethylene imine) (PEI). This three component injectable system can form a precipitated gel at physiological temperature due to the phase transition of PNIPAAm. The injection of glutaraldehyde into the gel core will adhere the implant to the surrounding tissues. (1)H NMR results indicated the successful physical incorporation of PEI into the PNIPAAm-PEG network by blending. In addition, the covalent crosslinking between the amine functionalities on the PEI and the aldehyde functionalities on the glutaraldehyde was verified using FTIR difference spectroscopy. Mechanical characterization of these blends showed a significant increase (p < 0.05) in compressive modulus following glutaraldehyde injection. The in vitro bioadhesive force studies with porcine skin showed a significant increase (p < 0.05) in the mean maximum force of detachment for PNIPAAm-PEG/PEI gels when glutaraldehyde was injected into the gel core. The results of this study indicate that the reactivity between amines and aldehyde functionalities can be exploited to impart bioadhesive properties to PNIPAAm-PEG/PEI copolymers.

  6. Poly(N-vinylpyrrolidone) hydrogels. Pt. 2; Hydrogel composites as wound dressing for tropical environment

    Energy Technology Data Exchange (ETDEWEB)

    Hilmy, N.; Darwis, D.; Hardiningsih, L. (Center for the Application of Isotopes and Radiation, BATAN, Jakarta (Indonesia))

    The effects of irradiation on hydration and other properties of poly(vinylpyrrolidone) (PVP) hydrogel composites have been investigated. The aqueous solution of vinylpyrrolidone (VP) 10 wt % was mixed with several additives such as agar and polyethylene glycol (PEG). The solution was then irradiated with gamma rays from a Cobalt-60 source at room temperature. Several parameters such as elongation at break (EB), tensile strength (TS), degree of swelling (DS), water vapor transmission rate (WVTR), equilibrium water content (EWC), microbial growth and penetration tests, and water activity (Aw) were analysed at room temperature of 29 [+-] 2[sup o]C humidity of 80 [+-] 10%. Such hydrogel membranes exhibit the following properties: they are elastic, transparent, flexible, impermeable for bacteria. They absorb a high capacity of water, attach to healthy skin but not to the wound and they are easy to remove. These properties of the hydrogel membranes allow application as a wound dressing in a tropical environment. (author).

  7. Piezoresistive Chemical Sensors Based on Functionalized Hydrogels

    Directory of Open Access Journals (Sweden)

    Margarita Guenther

    2014-06-01

    Full Text Available Thin films of analyte-specific hydrogels were combined with microfabricated piezoresistive pressure transducers to obtain chemomechanical sensors that can serve as selective biochemical sensors for a continuous monitoring of metabolites. The gel swelling pressure has been monitored in simulated physiological solutions by means of the output signal of piezoresistive sensors. The interference by fructose, human serum albumin, pH, and ionic concentration on glucose sensing was studied. With the help of a database containing the calibration curves of the hydrogel-based sensors at different values of pH and ionic strength, the corrected values of pH and glucose concentration were determined using a novel calibration algorithm.

  8. Protease-degradable electrospun fibrous hydrogels

    Science.gov (United States)

    Wade, Ryan J.; Bassin, Ethan J.; Rodell, Christopher B.; Burdick, Jason A.

    2015-03-01

    Electrospun nanofibres are promising in biomedical applications to replicate features of the natural extracellular matrix (ECM). However, nearly all electrospun scaffolds are either non-degradable or degrade hydrolytically, whereas natural ECM degrades proteolytically, often through matrix metalloproteinases. Here we synthesize reactive macromers that contain protease-cleavable and fluorescent peptides and are able to form both isotropic hydrogels and electrospun fibrous hydrogels through a photoinitiated polymerization. These biomimetic scaffolds are susceptible to protease-mediated cleavage in vitro in a protease dose-dependent manner and in vivo in a subcutaneous mouse model using transdermal fluorescent imaging to monitor degradation. Importantly, materials containing an alternate and non-protease-cleavable peptide sequence are stable in both in vitro and in vivo settings. To illustrate the specificity in degradation, scaffolds with mixed fibre populations support selective fibre degradation based on individual fibre degradability. Overall, this represents a novel biomimetic approach to generate protease-sensitive fibrous scaffolds for biomedical applications.

  9. Biomimetic Membrane Arrays on Cast Hydrogel Supports

    DEFF Research Database (Denmark)

    Roerdink-Lander, Monique; Ibragimova, Sania; Rein Hansen, Christian;

    2011-01-01

    Lipid bilayers are intrinsically fragile and require mechanical support in technical applications based on biomimetic membranes. Tethering the lipid bilayer membranes to solid substrates, either directly through covalent or ionic substrate−lipid links or indirectly on substrate-supported cushions......, provides mechanical support but at the cost of small molecule transport through the membrane−support sandwich. To stabilize biomimetic membranes while allowing transport through a membrane−support sandwich, we have investigated the feasibility of using an ethylene tetrafluoroethylene (ETFE......)/hydrogel sandwich as the support. The sandwich is realized as a perforated surface-treated ETFE film onto which a hydrogel composite support structure is cast. We report a simple method to prepare arrays of lipid bilayer membranes with low intrinsic electrical conductance on the highly permeable, self...

  10. Using hydrogels in microscopy: A tutorial.

    Science.gov (United States)

    Flood, Peter; Page, Henry; Reynaud, Emmanuel G

    2016-05-01

    Sample preparation for microscopy is a crucial step to ensure the best experimental outcome. It often requires the use of specific mounting media that have to be tailored to not just the sample but the chosen microscopy technique. The media must not damage the sample or impair the optical path, and may also have to support the correct physiological function/development of the sample. For decades, researchers have used embedding media such as hydrogels to maintain samples in place. Their ease of use and transparency has promoted them as mainstream mounting media. However, they are not as straightforward to implement as assumed. They can contain contaminants, generate forces on the sample, have complex diffusion and structural properties that are influenced by multiple factors and are generally not designed for microscopy in mind. This short review will discuss the advantages and disadvantages of using hydrogels for microscopy sample preparation and highlight some of the less obvious problems associated with the area.

  11. Preparation of Polyphosphazene Hydrogels for Enzyme Immobilization

    Directory of Open Access Journals (Sweden)

    Yue-Cheng Qian

    2014-07-01

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

  12. Hydrogels for central nervous system therapeutic strategies.

    Science.gov (United States)

    Russo, Teresa; Tunesi, Marta; Giordano, Carmen; Gloria, Antonio; Ambrosio, Luigi

    2015-12-01

    The central nervous system shows a limited regenerative capacity, and injuries or diseases, such as those in the spinal, brain and retina, are a great problem since current therapies seem to be unable to achieve good results in terms of significant functional recovery. Different promising therapies have been suggested, the aim being to restore at least some of the lost functions. The current review deals with the use of hydrogels in developing advanced devices for central nervous system therapeutic strategies. Several approaches, involving cell-based therapy, delivery of bioactive molecules and nanoparticle-based drug delivery, will be first reviewed. Finally, some examples of injectable hydrogels for the delivery of bioactive molecules in central nervous system will be reported, and the key features as well as the basic principles in designing multifunctional devices will be described.

  13. Blended education for systems architecting evaluation of the initial blended course version

    NARCIS (Netherlands)

    Muller, G.; Aker, J. van den; Postema, H.

    2016-01-01

    Blended education, the combination of traditional face-To-face education with online possibilities, is seen as the way for the future in education. Challenge for course providers is to learn how to offer blended education and to make the transition toward blended education. In this paper, we

  14. Blended education for systems architecting evaluation of the initial blended course version

    NARCIS (Netherlands)

    Muller, G.; Aker, J. van den; Postema, H.

    2016-01-01

    Blended education, the combination of traditional face-To-face education with online possibilities, is seen as the way for the future in education. Challenge for course providers is to learn how to offer blended education and to make the transition toward blended education. In this paper, we evaluat

  15. 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.

  16. Measurement errors related to contact angle analysis of hydrogel and silicone hydrogel contact lenses.

    Science.gov (United States)

    Read, Michael L; Morgan, Philip B; Maldonado-Codina, Carole

    2009-11-01

    This work sought to undertake a comprehensive investigation of the measurement errors associated with contact angle assessment of curved hydrogel contact lens surfaces. The contact angle coefficient of repeatability (COR) associated with three measurement conditions (image analysis COR, intralens COR, and interlens COR) was determined by measuring the contact angles (using both sessile drop and captive bubble methods) for three silicone hydrogel lenses (senofilcon A, balafilcon A, lotrafilcon A) and one conventional hydrogel lens (etafilcon A). Image analysis COR values were about 2 degrees , whereas intralens COR values (95% confidence intervals) ranged from 4.0 degrees (3.3 degrees , 4.7 degrees ) (lotrafilcon A, captive bubble) to 10.2 degrees (8.4 degrees , 12.1 degrees ) (senofilcon A, sessile drop). Interlens COR values ranged from 4.5 degrees (3.7 degrees , 5.2 degrees ) (lotrafilcon A, captive bubble) to 16.5 degrees (13.6 degrees , 19.4 degrees ) (senofilcon A, sessile drop). Measurement error associated with image analysis was shown to be small as an absolute measure, although proportionally more significant for lenses with low contact angle. Sessile drop contact angles were typically less repeatable than captive bubble contact angles. For sessile drop measures, repeatability was poorer with the silicone hydrogel lenses when compared with the conventional hydrogel lens; this phenomenon was not observed for the captive bubble method, suggesting that methodological factors related to the sessile drop technique (such as surface dehydration and blotting) may play a role in the increased variability of contact angle measurements observed with silicone hydrogel contact lenses.

  17. Comparison of Development of Dry Eye in Conventional Hydrogel and Silicone Hydrogel Contact Lens Users

    Directory of Open Access Journals (Sweden)

    Rukiye Aydın

    2013-01-01

    Full Text Available Pur po se: To compare the level and severity of dry eye between conventional hydrogel and silicone hydrogel contact lens users by using dry eye questionnaires and clinical tests. Ma te ri al and Met hod: Forty-two contact lens users who attended the Cornea and Contact Lens Unit, Department of Ophthalmology at Dokuz Eylül University, were included in this study. The first group consisted of subjects who have used conventional hydrogel (CHL contact lens for minimum one year and maximum five years. The second group consisted of subjects who have used silicone hydrogel (SHL contact lens for minimum one year and maximum 5 years. Twenty healthy individuals with no history of contact lens use were included in the control group. OSDI (Ocular Surface Disease Index questionnaire was performed to all patients. The tear function was determined by Schirmer’s test and tear break-up time in all three groups. Re sults: There was no statistically significant OSDI score differences between CHL and SHL users. Nevertheless, it was noted that OSDI score in both groups was statistically higher than in the control group. There was no statistically significant difference in tear break-up time between CHL and SHL users. On the other hand, tear break-up time was significantly lower in both groups when compared to the control group. There was no significant difference among the groups for Schirmer scoring. Dis cus si on: The use of conventional hydrogel and silicone hydrogel lenses causes a decline in tear break-up time leading to dry eye symptoms. However, no differences were determined between CHL and SHL users with regard to the severity of dry eye symptoms. (Turk J Ophthalmol 2013; 43: 7-14

  18. Controlled Delivery of Vancomycin via Charged Hydrogels.

    Science.gov (United States)

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

    2016-01-01

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

  19. Controlled Angiogenesis in Peptide Nanofiber Composite Hydrogels

    OpenAIRE

    Wickremasinghe, Navindee C.; Kumar, Vivek A.; Shi, Siyu; Hartgerink, Jeffrey D.

    2015-01-01

    Multidomain peptide (MDP) nanofibers create scaffolds that can present bioactive cues to promote biological responses. Orthogonal self-assembly of MDPs and growth-factor-loaded liposomes generate supramolecular composite hydrogels. These composites can act as delivery vehicles with time-controlled release. Here we examine the controlled release of placental growth factor-1 (PlGF-1) for its ability to induce angiogenic responses. PlGF-1 was loaded either in MDP matrices or within liposomes bou...

  20. Controlled Delivery of Vancomycin via Charged Hydrogels.

    Directory of Open Access Journals (Sweden)

    Carl T Gustafson

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

  1. 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

  2. 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.

  3. Connections matter: channeled hydrogels to improve vascularization

    Directory of Open Access Journals (Sweden)

    Severin eMuehleder

    2014-11-01

    Full Text Available The use of cell-laden hydrogels to engineer soft tissue has been emerging within the past years. Despite several newly developed and sophisticated techniques to encapsulate different cell types the importance of vascularization of the engineered constructs is often underestimated. As a result, cell death within a construct leads to impaired function and inclusion of the implant. Here, we discuss the fabrication of hollow channels within hydrogels as a promising strategy to facilitate vascularization. Furthermore, we present an overview on the feasible use of removable spacers, 3D laser- and planar processing strategies to create channels within hydrogels. The implementation of these structures promotes control over cell distribution and increases oxygen transport and nutrient supply in vitro. However, many studies lack the use of endothelial cells in their approaches leaving out an important factor to enhance vessel ingrowth and anastomosis formation upon implantation. In addition, the adequate endothelial cell type needs to be considered to make these approaches bridge the gap to in vivo applications.

  4. Chitosan Hydrogel Structure Modulated by Metal Ions

    Science.gov (United States)

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-10-01

    As one of the most important polysaccharide, chitosan (CS) has generated a great deal of interest for its desirable properties and wide applications. In the utilization of CS materials, hydrogel is a major and vital branch. CS has the ability to coordinate with many metal ions by a chelation mechanism. While most researchers focused on the applications of complexes between CS and metal ions, the complexes can also influence gelation process and structure of CS hydrogel. In the present work, such influence was studied with different metal ions, revealing two different kinds of mechanisms. Strong affinity between CS and metal ions leads to structural transition from orientation to multi-layers, while weak affinity leads to composite gel with in-situ formed inorganic particles. The study gave a better understanding of the gelation mechanism and provided strategies for the modulation of hydrogel morphology, which benefited the design of new CS-based materials with hierarchical structure and facilitated the utilization of polysaccharide resources.

  5. Engineering hydrogels as extracellular matrix mimics.

    Science.gov (United States)

    Geckil, Hikmet; Xu, Feng; Zhang, Xiaohui; Moon, SangJun; Demirci, Utkan

    2010-04-01

    Extracellular matrix (ECM) is a complex cellular environment consisting of proteins, proteoglycans, and other soluble molecules. ECM provides structural support to mammalian cells and a regulatory milieu with a variety of important cell functions, including assembling cells into various tissues and organs, regulating growth and cell-cell communication. Developing a tailored in vitro cell culture environment that mimics the intricate and organized nanoscale meshwork of native ECM is desirable. Recent studies have shown the potential of hydrogels to mimic native ECM. Such an engineered native-like ECM is more likely to provide cells with rational cues for diagnostic and therapeutic studies. The research for novel biomaterials has led to an extension of the scope and techniques used to fabricate biomimetic hydrogel scaffolds for tissue engineering and regenerative medicine applications. In this article, we detail the progress of the current state-of-the-art engineering methods to create cell-encapsulating hydrogel tissue constructs as well as their applications in in vitro models in biomedicine.

  6. Novel thermosensitive chitosan hydrogels: in vivo evaluation.

    Science.gov (United States)

    Patois, Emilie; Osorio-da Cruz, Suzanne; Tille, Jean-Christophe; Walpoth, Beat; Gurny, Robert; Jordan, Olivier

    2009-11-01

    Chitosan is an attractive biopolymer for the preparation of hydrogels. Its unique combination of biocompatibility, biodegradability, bioadhesivity, and tissue-promoting abilities allows pharmaceutical applications. We investigated novel thermosensitive hydrogels based on chitosan homogeneously reacetylated to a deacetylation degree of about 50%, combined with selected polyols or polyoses such as trehalose, a nontoxic polysaccharide. The latter, a gel-inducing and lyoprotective agent enabled the formulation to be lyophilized and rehydrated without affecting the thermosensitive behavior. This made possible long-term storage and promoted its use in a clinical setup. The thermally induced sol-gel transition allowed injectability and in situ setting. Rheological characterization revealed that storage moduli could be increased by one decade by increasing the chitosan concentration from 1.4 to 2.2% (w/w). Evaluation in vivo provided evidence of in situ implant formation in subcutaneous tissue of Sprague-Dawley rats and permanence for up to 3 months. Histopathological analysis demonstrated a mild, chronic, inflammatory reaction that disappeared with the complete absorption of the gel implant over a few months period. Such in situ forming hydrogels could be advantageous for specific applications in drug delivery and tissue engineering.

  7. 21 CFR 878.4022 - Hydrogel wound dressing and burn dressing.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hydrogel wound dressing and burn dressing. 878... Hydrogel wound dressing and burn dressing. (a) Identification. A hydrogel wound dressing is a sterile or... percent) and capable of absorbing exudate. This classification does not include a hydrogel wound...

  8. Hydrogel microspheres from biodegradable polymers as drug delivery systems

    Science.gov (United States)

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

  9. A Photochromic Copolymer Hydrogel Contact Lens: From Synthesis to Application

    Directory of Open Access Journals (Sweden)

    Xiaoli Yang

    2016-01-01

    Full Text Available A photochromic poly(2-hydroxyl-ethyl methacrylate-N-vinylpyrrolidone-spironaphthoxazine hydrogel (p(HEMA-NVP-SPO has been designed and synthesized by free radical polymerization in this work. The chemical and structural information of hydrogels was investigated by IR spectra, equilibrium water content (EWC, and SEM. The IR spectra confirmed successful synthesis of copolymer. The domain of NVP contributed to not only EWC but also inner structure of hydrogel, while SPO had little influence on these properties of hydrogel. The photochromic behaviors of hydrogel including photochromic properties and thermal fading kinetics were systematically studied and compared with hydrogel made by immersing method. Results showed that when SPO was incorporated in hydrogel by polymerization, maximum absorbance wavelength got shorter, and the relaxation half-life became longer. In addition, salicylic acid as a drug model could be loaded into hydrogel by immersing method, and its sustained drug release in a given period was dependent on the characteristics of solution and loading time.

  10. Extracellular matrix hydrogels from decellularized tissues: Structure and function.

    Science.gov (United States)

    Saldin, Lindsey T; Cramer, Madeline C; Velankar, Sachin S; White, Lisa J; Badylak, Stephen F

    2017-02-01

    Extracellular matrix (ECM) bioscaffolds prepared from decellularized tissues have been used to facilitate constructive and functional tissue remodeling in a variety of clinical applications. The discovery that these ECM materials could be solubilized and subsequently manipulated to form hydrogels expanded their potential in vitro and in vivo utility; i.e. as culture substrates comparable to collagen or Matrigel, and as injectable materials that fill irregularly-shaped defects. The mechanisms by which ECM hydrogels direct cell behavior and influence remodeling outcomes are only partially understood, but likely include structural and biological signals retained from the native source tissue. The present review describes the utility, formation, and physical and biological characterization of ECM hydrogels. Two examples of clinical application are presented to demonstrate in vivo utility of ECM hydrogels in different organ systems. Finally, new research directions and clinical translation of ECM hydrogels are discussed. More than 70 papers have been published on extracellular matrix (ECM) hydrogels created from source tissue in almost every organ system. The present manuscript represents a review of ECM hydrogels and attempts to identify structure-function relationships that influence the tissue remodeling outcomes and gaps in the understanding thereof. There is a Phase 1 clinical trial now in progress for an ECM hydrogel. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. Functionalized graphene hydrogel-based high-performance supercapacitors.

    Science.gov (United States)

    Xu, Yuxi; Lin, Zhaoyang; Huang, Xiaoqing; Wang, Yang; Huang, Yu; Duan, Xiangfeng

    2013-10-25

    Functionalized graphene hydrogels are prepared by a one-step low-temperature reduction process and exhibit ultrahigh specific capacitances and excellent cycling stability in the aqueous electrolyte. Flexible solid-state supercapacitors based on functionalized graphene hydrogels are demonstrated with superior capacitive performances and extraordinary mechanical flexibility.

  12. Versatile click alginate hydrogels crosslinked via tetrazine-norbornene chemistry.

    Science.gov (United States)

    Desai, Rajiv M; Koshy, Sandeep T; Hilderbrand, Scott A; Mooney, David J; Joshi, Neel S

    2015-05-01

    Alginate hydrogels are well-characterized, biologically inert materials that are used in many biomedical applications for the delivery of drugs, proteins, and cells. Unfortunately, canonical covalently crosslinked alginate hydrogels are formed using chemical strategies that can be biologically harmful due to their lack of chemoselectivity. In this work we introduce tetrazine and norbornene groups to alginate polymer chains and subsequently form covalently crosslinked click alginate hydrogels capable of encapsulating cells without damaging them. The rapid, bioorthogonal, and specific click reaction is irreversible and allows for easy incorporation of cells with high post-encapsulation viability. The swelling and mechanical properties of the click alginate hydrogel can be tuned via the total polymer concentration and the stoichiometric ratio of the complementary click functional groups. The click alginate hydrogel can be modified after gelation to display cell adhesion peptides for 2D cell culture using thiol-ene chemistry. Furthermore, click alginate hydrogels are minimally inflammatory, maintain structural integrity over several months, and reject cell infiltration when injected subcutaneously in mice. Click alginate hydrogels combine the numerous benefits of alginate hydrogels with powerful bioorthogonal click chemistry for use in tissue engineering applications involving the stable encapsulation or delivery of cells or bioactive molecules.

  13. Preparation and assessment of ketamine hydrogels for prolonged ...

    African Journals Online (AJOL)

    produced 62.82 % analgesia), the effect of the test formulations seem good for probable therapeutic use. ... The other chemicals ... Table 1: Composition of ketamine hydrogel ... The hydrogels were assessed for colour, ... hair and other fatty and connective tissues) with .... was administered to humans at a dose range of.

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

    Science.gov (United States)

    Nie, Jingyi; Wang, Zhengke; Hu, Qiaoling

    2016-10-01

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

  15. Reinforcement of hydrogels using three-dimensionally printed microfibres

    NARCIS (Netherlands)

    Visser, Jetze; Melchels, Ferry P. W.; Jeon, June E.; van Bussel, Erik M.; Kimpton, Laura S.; Byrne, Helen M.; Dhert, Wouter J. A.; Dalton, Paul D.; Hutmacher, Dietmar W.; Malda, J

    2015-01-01

    Despite intensive research, hydrogels currently available for tissue repair in the musculoskeletal system are unable to meet the mechanical, as well as the biological, requirements for successful outcomes. Here we reinforce soft hydrogels with highly organized, high-porosity microfibre networks that

  16. 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.

  17. Lab-on-a-chip devices with patterned hydrogels

    NARCIS (Netherlands)

    Gümüscü, B.

    2016-01-01

    Hydrogels are considered to be in the class of smart materials that find application in diagnostic, therapeutic,and fundamental science tools for miniaturized total analysis systems. In this thesis, the focus is on three major applications of patterned hydrogels, which are explored as an alternative

  18. Hydrogel-based sensor for CO2 measurements

    NARCIS (Netherlands)

    Herber, S.; Olthuis, W.; Bergveld, P.; Berg, van den A.

    2004-01-01

    A hydrogel-based sensor is presented for CO2 measurements. The sensor consists of a pressure sensor and porous silicon cover. A pH-sensitive hydrogel is confined between the two parts. Furthermore the porous cover contains a bicarbonate solution and a gaspermeable membrane. CO2 reacts with the solut

  19. Synthesis and Swelling Properties of Thermosensitive Hydrogels based on Terpolymerization

    Institute of Scientific and Technical Information of China (English)

    Cai Hua NI; Xian Yu ZENG; He HUANG

    2005-01-01

    Novel thermosensitive hydrogels based on polymerization of N-isopropyl acrylamide,Sodium acrylate, and diacetone acrylamide were synthesized. The swelling ratio and dynamic swelling were investigated. The results indicated that the hydrogels exhibited high water uptake and themosensitivity. The swelling properties and volume phase transition temperature could be adjusted by contents of the comonomers in the gels.

  20. Keratin sponge/hydrogel II, active agent delivery

    Science.gov (United States)

    Keratin sponge/hydrogels from oxidation and reduction hydrolysis of fine and coarse wool fibers were formed to behave as cationic hydrogels to swell and release active agents in the specific region of the gastro-intestinal (GI) tract. Their porous, interpenetrating networks (IPN) were effective for...

  1. 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.

  2. Injectable hyaluronic acid hydrogel for 19F magnetic resonance imaging

    NARCIS (Netherlands)

    Yang, X.; Sun, Y.; Kootala, S.; Hilborn, J.; Heerschap, A.; Ossipov, D.

    2014-01-01

    We report on a 19F labeled injectable hyaluronic acid (HA) hydrogel that can be monitored by both 1H and 19F MR imaging. The HA based hydrogel formed via carbazone reaction can be obtained within a minute by simple mixing of HA-carbazate and HA-aldehyde derivatized polymers. 19F contrast agent was l

  3. Application of hydrogels in heart valve tissue engineering.

    Science.gov (United States)

    Zhang, Xing; Xu, Bin; Puperi, Daniel S; Wu, Yan; West, Jennifer L; Grande-Allen, K Jane

    2015-01-01

    With an increasing number of patients requiring valve replacements, there is heightened interest in advancing heart valve tissue engineering (HVTE) to provide solutions to the many limitations of current surgical treatments. A variety of materials have been developed as scaffolds for HVTE including natural polymers, synthetic polymers, and decellularized valvular matrices. Among them, biocompatible hydrogels are generating growing interest. Natural hydrogels, such as collagen and fibrin, generally show good bioactivity but poor mechanical durability. Synthetic hydrogels, on the other hand, have tunable mechanical properties; however, appropriate cell-matrix interactions are difficult to obtain. Moreover, hydrogels can be used as cell carriers when the cellular component is seeded into the polymer meshes or decellularized valve scaffolds. In this review, we discuss current research strategies for HVTE with an emphasis on hydrogel applications. The physicochemical properties and fabrication methods of these hydrogels, as well as their mechanical properties and bioactivities are described. Performance of some hydrogels including in vitro evaluation using bioreactors and in vivo tests in different animal models are also discussed. For future HVTE, it will be compelling to examine how hydrogels can be constructed from composite materials to replicate mechanical properties and mimic biological functions of the native heart valve.

  4. Self-assembly of polypyrrole/chitosan composite hydrogels.

    Science.gov (United States)

    Huang, Hao; Wu, Jiao; Lin, Xi; Li, Liang; Shang, Songmin; Yuen, Marcus Chun-wah; Yan, Guoping

    2013-06-05

    Hydrogels based on the polypyrrole (PPy)/chitosan (CS) composite are self-assembled and characterized for their electrical and swelling properties. The static polymerization of pyrrole monomer in aqueous solution containing CS is accompanied with the formation of PPy/CS composite hydrogel. The feed order in the reaction process plays a key role in the formation of the hydrogels. The participation of one-dimensional PPy blocks in the formation of the hydrogel network avoids a possible migration of PPy from the hydrogel. The effect of pH and ionic strength on the physical properties of PPy/CS composite hydrogels are investigated in detail. The results indicate that the pH-sensitive PPy/CS composite hydrogels show good water absorbencies in distilled water and saline solution. This method may open a new opportunity for the fabrication of composite hydrogels associating the biomacromolecules and conducting polymers, and the improvement of the comprehensive performance of the resulting products. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

    NARCIS (Netherlands)

    De Lathouder, K.M.; Smeltink, M.W.; Straathof, A.J.J.; Paasman, M.A.; Van de Sandt, E.J.A.X.; Kapteijn, F.; Moulijn, J.A.

    2008-01-01

    The objective of this work was to develop a hydrogel-coated monolith for the entrapment of penicillin G acylase (E. coli, PGA). After screening of different hydrogels, chitosan was chosen as the carrier material for the preparation of monolithic biocatalysts. This protocol leads to active immobilize

  6. 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.

  7. Macromolecular diffusion in self-assembling biodegradable thermosensitive hydrogels

    NARCIS (Netherlands)

    Vermonden, T.; Jena, S.S.; Barriet, D.; Censi, R.; Gucht, van der J.; Hennink, W.E.; Siegel, R.A.

    2010-01-01

    Hydrogel formation triggered by a change in temperature is an attractive mechanism for in situ gelling biomaterials for pharmaceutical applications such as the delivery of therapeutic proteins. In this study, hydrogels were prepared from ABA triblock polymers having thermosensitive poly(N-(2-hydroxy

  8. 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

  9. Rapid Determination of Three Pyrrolidones in Light Industrial Products by Ultra Performance Liquid Chromatography%超高效液相色谱法快速测定轻工产品中三种吡咯酮的研究

    Institute of Scientific and Technical Information of China (English)

    俞凌云; 吴孟茹; 金晶; 温演庆; 车颖欣; 董伟

    2015-01-01

    2-吡咯烷酮(PYR)、N-甲基吡咯烷酮(NMP)、N-乙基吡咯烷酮(NEP)是一类优良的有机溶剂,因其潜在的生殖毒性而被关注。本文利用超高效液相色谱-二极管阵列检测器建立检测皮革中PYR、NMP、NEP的简单方法,样品提取方法为40℃超声水浴提取,提取溶液为0.1%十二烷基磺酸钠水溶液。在优化的色谱条件下,三种吡咯酮的检出限在20μg/L~40μg/L,其回收率高于91.6%。这个方法被成功应用于测定轻工产品中的2-吡咯烷酮、N-甲基吡咯烷酮和N-乙基吡咯烷酮,比传统的气相色谱法准确度高,且提取步骤简单。%2-pyrrolidone (PYR), N-methyl pyrrolidone (NMP) and N-ethyl pyrrolidone (NEP) are a kind of excellent organic solvent, which have been focused on because of their potential reproductive toxicity. A simple method followed by ultra performance liquid chromatography (UPLC) with Photo-Diode Array detector (PDA) has been developed for the determination of 2-Pyrrolidone, N-methyl pyrrolidone and N-ethyl pyrrolidone in leather samples. 0.1% sodium dodecyl sulfonate aqueous solution was used for the ultrasonic extraction at 40℃. Under optimal conditions, the quantification limits for the desired compounds ranging from 20 to 40μg/L were obtained. The recoveries were higher than 91.6% . The proposed method was successfully applied to the determination of the target compounds in light industrial products with a higher sensitivity and simpler extraction than traditional gas chromatography methods.

  10. Structural study and preliminary biological evaluation on the collagen hydrogel crosslinked by γ-irradiation.

    Science.gov (United States)

    Zhang, Xiangmei; Xu, Ling; Huang, Xin; Wei, Shicheng; Zhai, Maolin

    2012-11-01

    Under γ-irradiation, concentrated collagen solutions yielded collagen hydrogels and liquid products. The molecular structure of collagen hydrogels and the source of the liquid products were studied. Furthermore, preliminary biological properties of the hydrogels were investigated. The results revealed that crosslinking occurred to form collagen hydrogel and the crosslinking density increased with the increasing of the absorbed dose, and the collagen hydrogels showed enhanced mechanical properties. Meanwhile, collagen underwent radiation degradation and water was squeezed out from hydrogel by contraction of hydrogel, yielding liquid products. Collagen hydrogels induced by γ-irradiation maintained the backbone structure of collagen, and tyrosine partially involved in crosslinking. The irradiated collagen hydrogels have higher denatured temperature, can promote fibroblasts proliferation, and their degradation rate in vivo depended on the absorbed dose. The comprehensive results suggested that the collagen hydrogels prepared by radiation crosslinking preserved the triple helical conformation, possessed improved thermal stability and mechanical properties, excellent biocompatibility, which is expected to favor its application as biomaterials.

  11. Computational Study of pH-sensitive Hydrogel-based Microfluidic Flow Controllers

    Directory of Open Access Journals (Sweden)

    Jundika C. Kurnia

    2011-08-01

    Full Text Available This computational study investigates the sensing and actuating behavior of a pH-sensitive hydrogel-based microfluidic flow controller. This hydrogel-based flow controller has inherent advantage in its unique stimuli-sensitive properties, removing the need for an external power supply. The predicted swelling behavior the hydrogel is validated with steady-state and transient experiments. We then demonstrate how the model is implemented to study the sensing and actuating behavior of hydrogels for different microfluidic flow channel/hydrogel configurations: e.g., for flow in a T-junction with single and multiple hydrogels. In short, the results suggest that the response of the hydrogel-based flow controller is slow. Therefore, two strategies to improve the response rate of the hydrogels are proposed and demonstrated. Finally, we highlight that the model can be extended to include other stimuli-responsive hydrogels such as thermo-, electric-, and glucose-sensitive hydrogels.

  12. Fabrication of Negative Charged Poly (Ethylene glycol)-diacrylate Hydrogel as a Bone Tissue Engineering scaffold

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-qi; LIU Jie; TAN Fei; XIE Wei

    2016-01-01

    Objective To improve the cell attachment of PEGDA hydrogel, the SMAS small molecule was used to modify the PEGDA hydrogel. The charged hydrogel would show improved cell attachment and enhanced protein adsorption caused by enhancement of electrostatic adsorption.Method In this study, a series of charged hydrogels were produced by adding different concentrations of charged small molecule monomer into the PEGDA solution. Then, we investigate the physicochemical and biological characteristics of charged hydrogels, including FTIR, swelling ratio, contact angle, cell attachment.Result The results indicate that the charged monomer had been successfully incorporated into PEGDA hydrogel. Meanwhile, the protein adsorption of the hydrogel increased with increasing concentration of charge modification. Moreover, compared to PEGDA hydrogel, the cell attachment significantly improved on the charged hydrogel.Conclusion The charged hydrogel would be a promising scaffold candidate for bone tissue engineering.

  13. 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)

  14. Engineered Polymeric Hydrogels for 3D Tissue Models

    Directory of Open Access Journals (Sweden)

    Sujin Park

    2016-01-01

    Full Text Available Polymeric biomaterials are widely used in a wide range of biomedical applications due to their unique properties, such as biocompatibility, multi-tunability and easy fabrication. Specifically, polymeric hydrogel materials are extensively utilized as therapeutic implants and therapeutic vehicles for tissue regeneration and drug delivery systems. Recently, hydrogels have been developed as artificial cellular microenvironments because of the structural and physiological similarity to native extracellular matrices. With recent advances in hydrogel materials, many researchers are creating three-dimensional tissue models using engineered hydrogels and various cell sources, which is a promising platform for tissue regeneration, drug discovery, alternatives to animal models and the study of basic cell biology. In this review, we discuss how polymeric hydrogels are used to create engineered tissue constructs. Specifically, we focus on emerging technologies to generate advanced tissue models that precisely recapitulate complex native tissues in vivo.

  15. Removal of toxic metal ions with magnetic hydrogels.

    Science.gov (United States)

    Ozay, Ozgur; Ekici, Sema; Baran, Yakup; Aktas, Nahit; Sahiner, Nurettin

    2009-09-01

    Hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were synthesized via photopolymerization technique and used for the preparation of magnetic responsive composite hydrogels. These composite hydrogels with magnetic properties were further utilized for the removal of toxic metal ions such as Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from aqueous environments. It was revealed that hydrogel networks with magnetic properties can effectively be utilized in the removal of pollutants. The results verified that magnetic iron particle containing p(AMPS) hydrogel networks provide advantageous over conventional techniques. Langmuir and Freundlich adsorption isotherms were applied for toxic metal removal and both isotherms were fit reasonably well for the metal ion absorptions.

  16. Engineering three-dimensional cell mechanical microenvironment with hydrogels.

    Science.gov (United States)

    Huang, Guoyou; Wang, Lin; Wang, Shuqi; Han, Yulong; Wu, Jinhui; Zhang, Qiancheng; Xu, Feng; Lu, Tian Jian

    2012-12-01

    Cell mechanical microenvironment (CMM) significantly affects cell behaviors such as spreading, migration, proliferation and differentiation. However, most studies on cell response to mechanical stimulation are based on two-dimensional (2D) planar substrates, which cannot mimic native three-dimensional (3D) CMM. Accumulating evidence has shown that there is a significant difference in cell behavior in 2D and 3D microenvironments. Among the materials used for engineering 3D CMM, hydrogels have gained increasing attention due to their tunable properties (e.g. chemical and mechanical properties). In this paper, we provide an overview of recent advances in engineering hydrogel-based 3D CMM. Effects of mechanical cues (e.g. hydrogel stiffness and externally induced stress/strain in hydrogels) on cell behaviors are described. A variety of approaches to load mechanical stimuli in 3D hydrogel-based constructs are also discussed.

  17. Advances in the Fabrication of Antimicrobial Hydrogels for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Carmen M. González-Henríquez

    2017-02-01

    Full Text Available This review describes, in an organized manner, the recent developments in the elaboration of hydrogels that possess antimicrobial activity. The fabrication of antibacterial hydrogels for biomedical applications that permits cell adhesion and proliferation still remains as an interesting challenge, in particular for tissue engineering applications. In this context, a large number of studies has been carried out in the design of hydrogels that serve as support for antimicrobial agents (nanoparticles, antibiotics, etc.. Another interesting approach is to use polymers with inherent antimicrobial activity provided by functional groups contained in their structures, such as quaternary ammonium salt or hydrogels fabricated from antimicrobial peptides (AMPs or natural polymers, such as chitosan. A summary of the different alternatives employed for this purpose is described in this review, considering their advantages and disadvantages. Finally, more recent methodologies that lead to more sophisticated hydrogels that are able to react to external stimuli are equally depicted in this review.

  18. States of Water in Hydrogels Containing with Glyceryl Methacrylate

    Institute of Scientific and Technical Information of China (English)

    LI Qin-hua; LIU Li; HUANG Zhi-rong; LIN Dong-qing

    2014-01-01

    Hydrogel materials were prepared by thermopolymerization with different content of glyceryl methacrylate and hydroxyethyl methacrylate. The different states of water in swelling hydrogels were described and studied by differential scanning calorimetry (DSC). It was found that the hydrophilicity of GMA was stronger than HEMA, the water content and bound water of GMA hydrogel are higher than HEMA hydrogel. With the increase of GMA content, the content of free water in hydrogel increased. When GMA content was lower than 50%, the increase of GMA content also increased the content of bound water; but when GMA content was higher than 50%, the increase of GMA content decreased the content of bound water, which was caused by the chain hydrogen bond formed on the GMA chain with hydroxyl group each other.

  19. 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.

  20. Radiation-chemical preparation of poly(vinyl alcohol) hydrogels

    Science.gov (United States)

    Duflot, Anastasia V.; Kitaeva, Natalia K.; Duflot, Vladimir R.

    2015-02-01

    This work reports the usage of method of radiation-chemical synthesis to prepare cross-linked hydrogels from poly(vinyl alcohol) modified with glycidyl methacrylate. Synthesis kinetics of modified poly(vinyl alcohol) and properties of hydrogels were studied. The gel fraction, swelling, mechanical properties, and water content of the hydrogels were measured. It was found that gel fraction increases with increasing radiation dose, concentration of modified poly(vinyl alcohol), and reaches 60%. It was established by differential scanning calorimetry that a fraction of the "bound" water in hydrogels is 50-70% and independent of gel fraction content. In addition to "bound" and "free" states, water in hydrogels is also present in the intermediate state.

  1. Thermoresponsive hydrogels in biomedical applications: A seven-year update.

    Science.gov (United States)

    Klouda, Leda

    2015-11-01

    Thermally responsive hydrogels modulate their gelation behavior upon temperature change. Aqueous solutions solidify into hydrogels when a critical temperature is reached. In biomedical applications, the change from ambient temperature to physiological temperature can be employed. Their potential as in situ forming biomaterials has rendered these hydrogels very attractive. Advances in drug delivery, tissue engineering and cell sheet engineering have been made in recent years with the use of thermoresponsive hydrogels. The scope of this article is to review the literature on thermosensitive hydrogels published over the past seven years. The article concentrates on natural polymers as well as synthetic polymers, including systems based on N-isopropylacrylamide (NIPAAm), poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO), poly(ethylene glycol) (PEG)-biodegradable polyester copolymers, poly(organophosphazenes) and 2-(dimethylamino) ethyl methacrylate (DMAEMA).

  2. Classification, processing and application of hydrogels: A review.

    Science.gov (United States)

    Ullah, Faheem; Othman, Muhammad Bisyrul Hafi; Javed, Fatima; Ahmad, Zulkifli; Md Akil, Hazizan

    2015-12-01

    This article aims to review the literature concerning the choice of selectivity for hydrogels based on classification, application and processing. Super porous hydrogels (SPHs) and superabsorbent polymers (SAPs) represent an innovative category of recent generation highlighted as an ideal mould system for the study of solution-dependent phenomena. Hydrogels, also termed as smart and/or hungry networks, are currently subject of considerable scientific research due to their potential in hi-tech applications in the biomedical, pharmaceutical, biotechnology, bioseparation, biosensor, agriculture, oil recovery and cosmetics fields. Smart hydrogels display a significant physiochemical change in response to small changes in the surroundings. However, such changes are reversible; therefore, the hydrogels are capable of returning to its initial state after a reaction as soon as the trigger is removed.

  3. Mechanics and chemical thermodynamics of a temperature-sensitive hydrogel

    Science.gov (United States)

    Cai, Shengqiang; Suo, Zhigang

    2011-03-01

    A temperature-sensitive hydrogel is a network of polymers containing monomers, whose interaction with water molecules can be tuned dramatically by changing temperature. In most cases, the swelling ratio of a temperature-sensitive hydrogel changes discontinuously upon heating above or cooling below a critical temperature, which is called volume phase transition. Interestingly, the coexistence of swollen phases and shrunk phases are frequently observed in the experiments for temperature-sensitive hydrogels and additionally, people have also discovered that a uniaxial force can induce phase transition in a temperature-sensitive gel bar .In order to understand these phenomena, we studied the mechanics and chemical thermodynamics of a temperature-sensitive hydrogel bar, by using the free-energy landscape of a bar made from PNIPAM gel. Following Gibbs, we plot the phase diagram of a temperature-sensitive hydrogel bar under uniaxial force. This work is supported by the NSF (CMMI-0800161) and by the MRSEC at Harvard University.

  4. Preparation and characterization of bioglass/polyvinyl alcohol composite hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Xu Hong [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Wang Yingjun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Zheng Yudong [College of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Chen Xiaofeng [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Ren Li [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Wu Gang [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Huang Xiaoshan [College of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2007-06-01

    In order to form firm active fixation with the adjacent bone, a new kind of bioactive composite hydrogel was prepared with polyvinyl alcohol (PVA) and bioglass (BG) through ultrasonic dispersion, heat-high-pressure and freeze/thawed technique. A digital speckle correlation method (DSCM) was utilized to characterize the mechanical properties of the series of BG/PVA composites. Results showed that at different load pressures, the composite hydrogel displayed different displacement and deformation in the V field. Results also showed that an increase of PVA percentage (15-30 wt%) or of bioglass percentage (2-10 wt%) in composite hydrogel could lead to an increase in the elastic compression modulus. Scanning electron microscope results indicated that bioglass was uniformly dispersed in the BG/PVA composite hydrogel. The BG/PVA composite hydrogel shows a promising prospect as a new bionic cartilage implantation material.

  5. Structuring of Interface-Modified Polymer Blends

    DEFF Research Database (Denmark)

    Lyngaae-Jørgensen, Jørgen

    1999-01-01

    The paper treats the case where blends of polystyrene (PS), poly (dimethylsiloxane) (PDMS) and a diblock copolymer of PS and PDMS are used as model materials. This modelsystem is predicted to be "stable" in discrete blends in simple shear flow. Stable in the sence that the block copolymer can not...

  6. A Review on Conceptual Blending Theory

    Institute of Scientific and Technical Information of China (English)

    刘丽

    2010-01-01

    The CBT(Conceptual Blending Theory)is rapidly emerging as a major force in cognitive science and provides a unifying umbrella framework for a range of cognitive phenomena.The present paper is to have a general review of the conceptual blending theory through illustrating its four-space theory in order to have a better comprehension of its nature.

  7. Storage studies on mustard oil blends.

    Science.gov (United States)

    Chugh, Bhawna; Dhawan, Kamal

    2014-04-01

    Mustard oil blends were investigated for fatty acid composition and oxidative stability during storage for 3 months at room temperature (15 °C to 35 °C). The blends were prepared using raw mustard oil with selected refined vegetable oils namely; palm, safflower, soybean, rice bran, sunflower and sesame oil (raw). The fatty acid compositions of all these blends were studied using GLC. The developed blends were found to obey the ideal fatty acid ratio as laid down by health agencies i.e. 1:2:1:: SFA:MUFA:PUFA. The oxidative stability of blends was studied by measuring peroxide value (PV), Kries and Thiobarbituric acid (TBA) test. Blends MPSu (mustard oil, palm oil and sunflower oil), MPT (mustard oil, palm oil and sesame oil) and MPGr (mustard oil, palm oil and groundnut oil) were more stable than other blends during storage. The presence of mustard oil in all blends might make them a healthier option for many consumers as it is a rich source of ω-3 fatty acids and has anti-carcinogenic properties.

  8. Enhancing Students' Language Skills through Blended Learning

    Science.gov (United States)

    Banditvilai, Choosri

    2016-01-01

    This paper presents a case study of using blended learning to enhance students' language skills and learner autonomy in an Asian university environment. Blended learning represents an educational environment for much of the world where computers and the Internet are readily available. It combines self-study with valuable face-to-face interaction…

  9. Preparing Teachers for Emerging Blended Learning Environments

    Science.gov (United States)

    Oliver, Kevin M.; Stallings, Dallas T.

    2014-01-01

    Blended learning environments that merge learning strategies, resources, and modes have been implemented in higher education settings for nearly two decades, and research has identified many positive effects. More recently, K-12 traditional and charter schools have begun to experiment with blended learning, but to date, research on the effects of…

  10. Improving Curriculum through Blended Learning Pedagogy

    Science.gov (United States)

    Darojat, Ojat

    2016-01-01

    This paper is a study of blended learning pedagogy in open and distance learning (ODL), involving two universities in Southeast Asia, STOU Thailand and UT Indonesia. The purpose of this study is to understand the issues related to the implementation of blended-learning pedagogy. Qualitative case study was employed to optimize my understanding of…

  11. Blended Learning in Personalized Assistive Learning Environments

    Science.gov (United States)

    Marinagi, Catherine; Skourlas, Christos

    2013-01-01

    In this paper, the special needs/requirements of disabled students and cost-benefits for applying blended learning in Personalized Educational Learning Environments (PELE) in Higher Education are studied. The authors describe how blended learning can form an attractive and helpful framework for assisting Deaf and Hard-of-Hearing (D-HH) students to…

  12. PAIRWISE BLENDING OF HIGH LEVEL WASTE (HLW)

    Energy Technology Data Exchange (ETDEWEB)

    CERTA, P.J.

    2006-02-22

    The primary objective of this study is to demonstrate a mission scenario that uses pairwise and incidental blending of high level waste (HLW) to reduce the total mass of HLW glass. Secondary objectives include understanding how recent refinements to the tank waste inventory and solubility assumptions affect the mass of HLW glass and how logistical constraints may affect the efficacy of HLW blending.

  13. Preparing Teachers for Emerging Blended Learning Environments

    Science.gov (United States)

    Oliver, Kevin M.; Stallings, Dallas T.

    2014-01-01

    Blended learning environments that merge learning strategies, resources, and modes have been implemented in higher education settings for nearly two decades, and research has identified many positive effects. More recently, K-12 traditional and charter schools have begun to experiment with blended learning, but to date, research on the effects of…

  14. Co-continuous polycarbonate/ABS blends

    NARCIS (Netherlands)

    Inberg, J.P.F.; Gaymans, R.J.

    2002-01-01

    Co-continuous PC/ABS (50/50) blends were studied with a variable polybutadiene (PB) content (0–40%) in ABS. Polycarbonate (PC), styrene-acrylonitrile (SAN) and PB were blended in two steps using a twin screw extruder. Rectangular bars were injection moulded and notched Izod impact tested at

  15. Structuring of Interface-Modified Polymer Blends

    DEFF Research Database (Denmark)

    Lyngaae-Jørgensen, Jørgen

    1999-01-01

    The paper treats the case where blends of polystyrene (PS), poly (dimethylsiloxane) (PDMS) and a diblock copolymer of PS and PDMS are used as model materials. This modelsystem is predicted to be "stable" in discrete blends in simple shear flow. Stable in the sence that the block copolymer can not...

  16. Study on combustion characteristics of blended coals

    Institute of Scientific and Technical Information of China (English)

    LI Yonghua; WANG Chunbo; CHEN Hongwei

    2007-01-01

    Power plants in China have to burn blended coal instead of one specific coal for a variety of reasons.So it is of great necessity to investigate the combustion of blended coals.Using a test rig with a capacity of 640 MJ/h with an absolute milling system and flue gas online analysis system,characteristics such as burnout,slag,and pollution of some blended coals were investigated.The ratio of coke and slag as a method of distinguishing coal slagging characteristic was introduced.The results show that the blending of coal has some effect on NOx but there is no obvious rule.SOx emission can be reduced by blending low sulfur coal.

  17. Compatibilizing Bulk Polymer Blends by using Organoclays

    Energy Technology Data Exchange (ETDEWEB)

    Si, Mayu; Araki, Tohru; Ade, Harald; Kilcoyne, A.L.D.; Fischer,Robert; Sokolov, Jonathan C.; Rafailovich, Miriam H.

    2006-03-28

    We have studied the morphology of blends of PS/PMMA,PC/SAN24, and PMMA/EVA and compared the morphologies with and withoutmodified organoclay Cloisite 20A or Cloisite 6A clays. In each case wefound a large reduction in domains size and the localization of the clayplatelets along the interfaces of the components. The increasedmiscibility was accompanied in some cases, with the reduction of thesystem from multiple values of the glass transition temperatures to one.In addition, the modulus of all the systems increased significantly. Amodel was proposed where it was proposed that in-situ grafts were formingon the clay surfaces during blending and the grafts then had to belocalized at the interfaces. This blending mechanism reflects thecomposition of the blend and is fairly nonspecific. As a result, this maybe a promising technology for use in processing recycled blends where thecomposition is often uncertain and price is of generalconcern.

  18. Hydrogel design of experiments methodology to optimize hydrogel for iPSC-NPC culture.

    Science.gov (United States)

    Lam, Jonathan; Carmichael, S Thomas; Lowry, William E; Segura, Tatiana

    2015-03-11

    Bioactive signals can be incorporated in hydrogels to direct encapsulated cell behavior. Design of experiments methodology methodically varies the signals systematically to determine the individual and combinatorial effects of each factor on cell activity. Using this approach enables the optimization of three ligands concentrations (RGD, YIGSR, IKVAV) for the survival and differentiation of neural progenitor cells.

  19. Improved electrical properties of Fe nanofiller impregnated PEO + PVP:Li+ blended polymer electrolytes for lithium battery applications

    Science.gov (United States)

    Naveen Kumar, K.; Saijyothi, K.; Kang, Misook; Ratnakaram, Y. C.; Hari Krishna, K.; Jin, Dahee; Lee, Yong Min

    2016-07-01

    Solid polymer-blended electrolyte films of polyethylene oxide (PEO) + polyvinyl pyrrolidone (PVP)/lithium perchlorate embedded with iron (Fe) nanofiller in different concentrations have been synthesized by a solution casting method. The semicrystalline nature of these polymer electrolyte films has been confirmed from their XRD profiles. Polymer complex formation and ion-polymer interactions are systematically studied by FTIR and laser Raman spectral analysis. Surface morphological studies are carried out from SEM analysis. Dispersed Fe nanofiller size evaluation study has been carried out using transmission electron microscopy (TEM). In order to evaluate the thermal stability, decomposition temperature, and thermogravimetric dynamics, we carried out the TG/DTA measurement. Upon addition of Fe nanofiller to the PEO + PVP/Li+ electrolyte system, it was found to result in the enhancement of ionic conductivity. The maximum ionic conductivity has been set up to be 1.14 × 10-4 Scm-1 at the optimized concentration of 4 wt% Fe nanofiller-embedded PEO + PVP/Li+ polymer electrolyte nanocomposite at an ambient temperature. PEO + PVP/Li+ + Fe nanofiller (4 wt%) cell exhibited better performance in terms of cell parameters. Based on the cell parameters, the 4 wt% Fe nanofiller-dispersed PEO + PVP/Li+ polymer electrolyte system could be suggested as a perspective candidate for solid-state battery applications.

  20. Solvent effects on the formation of nanoparticles and multilayered coatings based on hydrogen-bonded interpolymer complexes of poly(acrylic acid) with homo- and copolymers of N-vinyl pyrrolidone.

    Science.gov (United States)

    Zhunuspayev, Daulet E; Mun, Grigoriy A; Hole, Patrick; Khutoryanskiy, Vitaliy V

    2008-12-02

    The formation of hydrogen-bonded interpolymer complexes between poly(acrylic acid) and poly(N-vinyl pyrrolidone) as well as amphiphilic copolymers of N-vinyl pyrrolidone with vinyl propyl ether has been studied in aqueous and organic solutions. It was demonstrated that introduction of vinyl propyl ether units into the macromolecules of the nonionic polymer enhances their ability to form complexes in aqueous solutions due to more significant contribution of hydrophobic effects. The complexation was found to be a multistage process that involves the formation of primary polycomplex particles, which further aggregate to form spherical nanoparticles. Depending on the environmental factors (pH, solvent nature), these nanoparticles may either form stable colloidal solutions or undergo further aggregation, resulting in precipitation of interpolymer complexes. In organic solvents, the intensity of complex formation increases in the following order: methanol complexes on glass surfaces. It was demonstrated that the solvent nature affects the efficiency of coating deposition.

  1. Development and initial characterization of a chemically stabilized elastin-glycosaminoglycan-collagen composite shape-memory hydrogel for nucleus pulposus regeneration.

    Science.gov (United States)

    Mercuri, Jeremy; Addington, Caroline; Pascal, Richard; Gill, Sanjitpal; Simionescu, Dan

    2014-12-01

    Nucleus pulposus (NP) is a resilient and hydrophilic tissue which plays a significant role in the biomechanical function of the intervertebral disc (IVD). Destruction of the NP extracellular matrix (ECM) is observed during the early stages of IVD degeneration. Herein, we describe the development and initial characterization of a novel biomaterial which attempts to recreate the resilient and hydrophilic nature of the NP via the construction of a chemically stabilized elastin-glycosaminoglycan-collagen (EGC) composite hydrogel. Results demonstrated that a resilient, hydrophilic hydrogel which displays a unique "shape-memory" sponge characteristic could be formed from a blend of soluble elastin aggregates, chondroitin-6-sulfate, hyaluronic acid and collagen following freeze-drying, stabilization with a carbodiimide and penta-galloyl glucose-based fixative, and subsequent partial degradation with glycosaminoglycan degrading enzymes. The resultant material exhibited the ability to restore its original dimensions and water content following multi-cycle mechanical compression and illustrated resistance to accelerated enzymatic degradation. Preliminary in vitro studies utilizing human adipose derived stem cells (hADSCs) demonstrated that the material was cytocompatible and supported differentiation towards an NP cell-like phenotype. In vivo biocompatibility studies illustrated host cell infiltration and evidence of active remodeling following 4 weeks of implantation. Feasibility studies demonstrated that the EGC hydrogel could be delivered via minimally invasive methods.

  2. Multifunctional chitosan/polyvinyl pyrrolidone/45S5 Bioglass® scaffolds for MC3T3-E1 cell stimulation and drug release

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Qingqing [Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, 270 Xueyuan Xi Road, Wenzhou, Zhejiang 325027 (China); Li, Wei [Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Cauerstrasse 6, Erlangen 91058 (Germany); Yu, Shanshan; Ma, Liwei [Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, 270 Xueyuan Xi Road, Wenzhou, Zhejiang 325027 (China); Jin, Dayong [Institute for Biomedical Materials and Devices, Faculty of Science, University of Technology Sydney, NSW 2007 (Australia); Advanced Cytometry Labs, ARC Center of Excellence for Nanoscale BioPhotonics, Macquarie University, Sydney, NSW 2109 (Australia); Boccaccini, Aldo R., E-mail: Aldo.Boccaccini@ww.uni-erlangen.de [Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Cauerstrasse 6, Erlangen 91058 (Germany); Liu, Yong, E-mail: yongliu1980@hotmail.com [Institute of Advanced Materials for Nano-Bio Applications, School of Ophthalmology & Optometry, Wenzhou Medical University, 270 Xueyuan Xi Road, Wenzhou, Zhejiang 325027 (China); Advanced Cytometry Labs, ARC Center of Excellence for Nanoscale BioPhotonics, Macquarie University, Sydney, NSW 2109 (Australia)

    2015-11-01

    Novel chitosan–polyvinyl pyrrolidone/45S5 Bioglass® (CS-PVP/BG) scaffolds were prepared via foam replication and chemical cross-linking techniques. The pristine BG, CS-PVP coated BG and genipin cross-linked CS-PVP/BG (G-CS-PVP/BG) scaffolds were synthesized and characterized in terms of chemical composition, physical structure and morphology respectively. Resistance to enzymatic degradation of the scaffold is improved significantly with the use of genipin cross-linked CS-PVP. The bio-effects of scaffolds on MC3T3-E1 osteoblast-like cells were evaluated by studying cell viability, adhesion and proliferation. The CCK-8 assay shows that cell viability on the resulting G-CS-PVP/BG scaffold is improved obviously after cross-linking of genipin. Cell skeleton images exhibit that well-stretched F-actin bundles are obtained on the G-CS-PVP/BG scaffold. SEM results present significant improvement on the cell adhesion and proliferation for cells cultured on the G-CS-PVP/BG scaffold. The drug release performance on the as-synthesized scaffold was studied in a phosphate buffered saline (PBS) solution. Vancomycin is found to be released in burst fashion within 24 h from the pristine BG scaffold, however, the release period from the G-CS-PVP/BG scaffold is enhanced to 7 days, indicating improved drug release properties of the G-CS-PVP/BG scaffold. Our results suggest that the G-CS-PVP/BG scaffolds possess promising physicochemical properties, sustained drug release capability and good biocompatibility for MC3T3-E1 cells' proliferation and adhesion, suggesting their potential applications in areas such as MC3T3-E1 cell stimulation and bone tissue engineering. - Highlights: • Novel genipi–chitosan–polyvinyl pyrrolidone/45S5 Bioglass® scaffolds are prepared. • Resistance to enzymatic degradation of the scaffold is improved significantly. • The resulting scaffold shows enhanced MC3T3-E1 cell adhesion and proliferation. • Release of antibiotic vancomycin from the

  3. Preparation of planar CH{sub 3}NH{sub 3}PbI{sub 3} thin films with controlled size using 1-ethyl-2-pyrrolidone as solvent

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Qiuyan; Chu, Yixia [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Zheng, Xuerong [Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Liu, Zhenya; Liang, Liming [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Qi, Jiakun [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Xin [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu, Gang [School of Chemical Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu, Hui, E-mail: liuhuihebut@163.com [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Chen, Hongjian [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu, Caichi, E-mail: ccliu@hebut.edu.cn [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China)

    2016-06-25

    Recently, planar perovskite solar cells based on CH{sub 3}NH{sub 3}PbI{sub 3} have attracted many researcher's interest due to their unique advantages such as simple cell architecture, easy fabrication and potential multijunction construction comparing to the initial mesoporous structure. However, the preparation of planar perovskite films with high quality is still in challenge. In this paper, we developed a vapor-assisted solution process using a novel and green solvent of 1-Ethyl-2-pyrrolidone (NEP) instead of the traditional N, N-dimethylformamide (DMF) to construct a high-quality perovskite CH{sub 3}NH{sub 3}PbI{sub 3} thin film with pure phase, high compactness, small surface roughness and controlled size. The phase evolution and growth mechanism of the perovskite films are also discussed. Utilizing the NEP of low volatility and moderate boiling point as solvent, we dried the PbI{sub 2}-NEP precursor films at different temperature under vacuum and then obtained PbI{sub 2} thin films with different crystalline degree from amorphous to highly crystalline. The perovskite films with crystal size ranged from hundreds of nanometers to several micrometers can be prepared by reacting the PbI{sub 2} films of different crystalline degree with CH{sub 3}NH{sub 3}I vapor. Moreover, planar-structured solar cells combining the perovskite film with TiO{sub 2} and spiro-OMeTAD as the electron and holes transporting layer achieves a power conversion efficiency of 10.2%. - Highlights: • A novel and green solvent of 1-Ethyl-2-pyrrolidone (NEP) was used to construct high-quality perovskite CH{sub 3}NH{sub 3}PbI{sub 3} thin film. • The CH{sub 3}NH{sub 3}PbI{sub 3} grain with different sizes ranged from hundreds of nanometers to several micrometers can be obtained. • Planar-structured perovskite CH{sub 3}NH{sub 3}PbI{sub 3} solar cells using NEP as solvent achieves a power conversion efficiency of 10.2%.

  4. A Hyaluronan-Based Injectable Hydrogel Improves the Survival and Integration of Stem Cell Progeny following Transplantation

    Directory of Open Access Journals (Sweden)

    Brian G. Ballios

    2015-06-01

    Full Text Available The utility of stem cells and their progeny in adult transplantation models has been limited by poor survival and integration. We designed an injectable and bioresorbable hydrogel blend of hyaluronan and methylcellulose (HAMC and tested it with two cell types in two animal models, thereby gaining an understanding of its general applicability for enhanced cell distribution, survival, integration, and functional repair relative to conventional cell delivery in saline. HAMC improves cell survival and integration of retinal stem cell (RSC-derived rods in the retina. The pro-survival mechanism of HAMC is ascribed to the interaction of the CD44 receptor with HA. Transient disruption of the retinal outer limiting membrane, combined with HAMC delivery, results in significantly improved rod survival and visual function. HAMC also improves the distribution, viability, and functional repair of neural stem and progenitor cells (NSCs. The HAMC delivery system improves cell transplantation efficacy in two CNS models, suggesting broad applicability.

  5. Poly (n-vinyl-2-pyrrolidone) gels and dimethyl siloxanes and ethylene oxides copolymers crosslinked by ionizing radiation; Geis de poli (n-vivil-2-pirrolidona) e copolimeros de dimetilsiloxano e oxido de etileno reticulados por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Souza, A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Nunes, S.P. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica

    1995-12-31

    Poly(N-vinyl-2-pyrrolidone) (PVP) gels, crosslinked by irradiation, have been used for healing of wounds. In this work, a hydrophilic copolymer (dimethyl siloxanes and ethylene oxy - SEO), is added to PVP to improve the mechanical properties. The characterization was performed by DMA, showing that SEO increases the film flexibility, but an excess can inhibit the PVP crosslinking. Crosslinking with electron beam was more effective than with Co-60 source. (author). 5 refs., 2 figs.

  6. 吡咯烷酮羧酸钠吸附卷烟烟气中亚硝胺的研究%Study on L-pyrrolidone Carboxylic Acid-Na to Absorb the N-nitrosamine in Cigarette Smoke

    Institute of Scientific and Technical Information of China (English)

    黄天辉; 黄泰松; 邹克兴; 刘启斌; 李志华; 潘连华

    2012-01-01

    [目的]研究吡咯烷酮羧酸钠对降低卷烟气中亚硝胺的释放量的影响.[方法]对添加吡略烷酮羧酸钠的卷烟的感官指标、物理指标和化学指标进行评价.[结果]与对照烟相比,添加吡咯烷酮羧酸钠的卷烟在香气、刺激性、协调性、杂气和余味等感官指标上有较大的改善;在重量、吸阻、圆周、园度和硬度等物理指标上无明显变化;在焦油、一氧化碳、烟碱、N-亚硝胺等化学指标上均有所降低.[结论]吡咯烷酮羧酸钠对降低卷烟气中焦油、一氧化碳、烟碱、N-亚硝胺等有害成分有一定的效果.%[Objective] To study effects of L-pyrrolidone carboxylic acid-Na on reducing N-nitrosamine in cigarette smoke. [Method] The sensory index, physical index and chemical index in cigarette added with L-pyrrolidone carboxylic acid-Na were evaluated. [Result] Compared with control tobacco, cigarettes added with L-pyrrolidone carboxylic acid-Na was improved in fragrance, throat irritation, harmoniousness, mixed gas and aftertaste, resembled at weight, resistance, roundness and rigidity, and reduced at tar, carbon monoxide, nicotine and N-nitrosamine. [ Conclusion ] L-pyrrolidone carboxylic acid-Na was efficient to reduce the harmful ingredients such as tar, carbon monoxide, nicotine and N-nitrosamine in cigarette smoke.

  7. THE EFFECT OF BLENDING SEQUENCE ON PHASE MORPHOLOGY OF NYLON 6/ABS/SMA BLENDS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The preparation process-dependent phase morphology of blends composed of nylon 6 and acryionitrile-butadienestyrene(ABS)over a composition range of 30-70 wt% using a styrene-maleic anhydride(SMA)copolymer as the compatibilizing agent with a constant content(5phr)was investigated.The results of the scanning electron microscope (SEM)observation revealed that compared with the binary blends of nylon 6 and ABS,the existence of SMA caused a composition shift of phase inversion to a higher weight fraction of nylon 6 when ABS was blended with the preblended nylon 6/SMA blend,while the co-continuous structures could be observed over a considerably narrower composition range when nylon 6 was blended with the pre-blended ABS/SMA blend.An examination through dynamic mechanical analysis (DMA)tests confirmed the results obtained with SEM.It is found that near the phase inversion region a remarkable change in the dynamic storage modulus(G')and the loss tangent(tanδ)appears.Moreover,the influence of blending sequence on the size of dispersed particles has been probed for uncompatibilized and compatibilized blends of nylon 6 and ABS over a wide range of compositions below or beyond the phase inversion points.For the blends of ABS dispersed in a nylon 6 matrix,little discernible effects of blending sequence on particle size could be observed.Furthermore,there exists a significant difference in morphologies of the blends prepared by nylon 6 particles dispersing in a ABS matrix in cases of different blending sequences used.Some possible factors responsible for the above asymmetric behaviors have been proposed.

  8. Soft nanotube hydrogels functioning as artificial chaperones.

    Science.gov (United States)

    Kameta, Naohiro; Masuda, Mitsutoshi; Shimizu, Toshimi

    2012-06-26

    Self-assembly of rationally designed asymmetric amphiphilic monomers in water produced nanotube hydrogels in the presence of chemically denatured proteins (green fluorescent protein, carbonic anhydrase, and citrate synthase) at room temperature, which were able to encapsulate the proteins in the one-dimensional channel of the nanotube consisting of a monolayer membrane. Decreasing the concentrations of the denaturants induced refolding of part of the encapsulated proteins in the nanotube channel. Changing the pH dramatically reduced electrostatic attraction between the inner surface mainly covered with amino groups of the nanotube channel and the encapsulated proteins. As a result, the refolded proteins were smoothly released into the bulk solution without specific additive agents. This recovery procedure also transformed the encapsulated proteins from an intermediately refolding state to a completely refolded state. Thus, the nanotube hydrogels assisted the refolding of the denatured proteins and acted as artificial chaperones. Introduction of hydrophobic sites such as a benzyloxycarbony group and a tert-butoxycarbonyl group onto the inner surface of the nanotube channels remarkably enhanced the encapsulation and refolding efficiencies based on the hydrophobic interactions between the groups and the surface-exposed hydrophobic amino acid residues of the intermediates in the refolding process. Refolding was strongly dependent on the inner diameters of the nanotube channels. Supramolecular nanotechnology allowed us to not only precisely control the diameters of the nanotube channels but also functionalize their surfaces, enabling us to fine-tune the biocompatibility. Hence, these nanotube hydrogel systems should be widely applicable to various target proteins of different molecular weights, charges, and conformations.

  9. Blending traditional and digital marketing

    Directory of Open Access Journals (Sweden)

    Raluca Dania TODOR

    2016-07-01

    Full Text Available It is a matter of fact that we are in the digital era and internet marketing and social media have a significant impact on the way consumers behave, companies do business and it is a must for companies to adapt to the new reality. Due to the fast evolution of the technology, the continuous increase in demand and supply, the supply chain elongation and the big amount of date, the only solution to face the major changes is the automation of all the processes. But even though the new era of communication is here, specialist suggest that companies should not ignore traditional methods, and to try to blend digital marketing with traditional campaigns in order to achieve their goals.

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

    Science.gov (United States)

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

    2007-01-01

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

  11. Magnetic hydrogel nanocomposites as remote controlled microfluidic valves.

    Science.gov (United States)

    Satarkar, Nitin S; Zhang, Wenli; Eitel, Richard E; Hilt, J Zach

    2009-06-21

    In recent years, hydrogels have attracted attention as active components in microfluidic devices. Here, we present a demonstration of remote controlled flow regulation in a microfluidic device using a hydrogel nanocomposite valve. To create the nanocomposite hydrogel, magnetic nanoparticles were dispersed in temperature-responsive N-isopropylacrylamide (NIPAAm) hydrogels. The swelling and collapse of the resultant nanocomposite can be remotely controlled by application of an alternating magnetic field (AMF). A ceramic microfluidic device with Y-junction channels was fabricated using low temperature co-fired ceramic (LTCC) technology. The nanocomposite was incorporated as a valve in one of the channels of the device. An AMF of frequency 293 kHz was then applied to the device and ON-OFF control on flow was achieved. A pressure transducer was placed at the inlet of the channel and pressure measurements were done for multiple AMF ON-OFF cycles to evaluate the reproducibility of the valve. Furthermore, the effect of the hydrogel geometry on the response time was characterized by hydrogels with different dimensions. Magnetic hydrogel nanocomposite films of different thicknesses (0.5, 1, 1.5 mm) were subjected to AMF and the kinetics of collapse and recovery were studied.

  12. Laminin-111 enriched fibrin hydrogels for skeletal muscle regeneration.

    Science.gov (United States)

    Marcinczyk, Madison; Elmashhady, Hady; Talovic, Muhamed; Dunn, Andrew; Bugis, Faiz; Garg, Koyal

    2017-10-01

    Laminin (LM)-111 supplementation has improved muscle regeneration in several models of disease and injury. This study investigated a novel hydrogel composed of fibrinogen and LM-111. Increasing LM-111 concentration (50-450 μg/mL) in fibrin hydrogels resulted in highly fibrous scaffolds with progressively thinner interlaced fibers. Rheological testing showed that all hydrogels had viscoelastic behavior and the Young's modulus ranged from 2-6KPa. C2C12 myobalsts showed a significant increase in VEGF production and decrease in IL-6 production on LM-111 enriched fibrin hydrogels as compared to pure fibrin hydrogels on day 4. Western blotting results showed a significant increase in MyoD and desmin protein quantity but a significant decrease in myogenin protein quantity in myoblasts cultured on the LM-111 (450 μg/mL) enriched fibrin hydrogel. Combined application of electromechanical stimulation significantly enhanced the production of VEGF and IGF-1 from myoblast seeded fibrin-LM-111 hydrogels. Taken together, these observations offer an important first step toward optimizing a tissue engineered constructs for skeletal muscle regeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Electrically responsive smart hydrogels in drug delivery: a review.

    Science.gov (United States)

    Kulkarni, R V; Biswanath, Sa

    2007-01-01

    Recently, much of the research activity has been focused on the development of stimuli-responsive hydrogels. Such hydrogels can show a response to the external or internal stimuli in the form of rapid changes in the physical nature of the polymeric network. This hydrogel property can be utilized for drug delivery applications. A literature search suggests that current research related to stimuli responsive drug delivery systems deals with temperature sensitive, pH sensitive, glucose sensitive and bio-molecule sensitive hydrogels. Electrically responsive hydrogels have also been recently developed in the form of gel matrices, implants and membranes for drug delivery. Control over the release of drugs such as quantity and timing, is essential to optimize drug therapy. Reports say that the electrically controlled in vitro and in vivo drug release studies have been carried out on polyelectrolyte hydrogels. A pulsatile pattern of drug release was achieved with the alternative application and removal of the electrical stimulus. This article gives an overview of the latest developments in the formulation of drug delivery systems using electrically responsive hydrogels.

  14. Capillary Origami Inspired Fabrication of Complex 3D Hydrogel Constructs.

    Science.gov (United States)

    Li, Moxiao; Yang, Qingzhen; Liu, Hao; Qiu, Mushu; Lu, Tian Jian; Xu, Feng

    2016-09-01

    Hydrogels have found broad applications in various engineering and biomedical fields, where the shape and size of hydrogels can profoundly influence their functions. Although numerous methods have been developed to tailor 3D hydrogel structures, it is still challenging to fabricate complex 3D hydrogel constructs. Inspired by the capillary origami phenomenon where surface tension of a droplet on an elastic membrane can induce spontaneous folding of the membrane into 3D structures along with droplet evaporation, a facile strategy is established for the fabrication of complex 3D hydrogel constructs with programmable shapes and sizes by crosslinking hydrogels during the folding process. A mathematical model is further proposed to predict the temporal structure evolution of the folded 3D hydrogel constructs. Using this model, precise control is achieved over the 3D shapes (e.g., pyramid, pentahedron, and cube) and sizes (ranging from hundreds of micrometers to millimeters) through tuning membrane shape, dimensionless parameter of the process (elastocapillary number Ce ), and evaporation time. This work would be favorable to multiple areas, such as flexible electronics, tissue regeneration, and drug delivery.

  15. 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.

  16. Evaluation of photocrosslinked Lutrol hydrogel for tissue printing applications.

    Science.gov (United States)

    Fedorovich, Natalja E; Swennen, Ives; Girones, Jordi; Moroni, Lorenzo; van Blitterswijk, Clemens A; Schacht, Etienne; Alblas, Jacqueline; Dhert, Wouter J A

    2009-07-13

    Application of hydrogels in tissue engineering and innovative strategies such as organ printing, which is based on layered 3D deposition of cell-laden hydrogels, requires design of novel hydrogel matrices. Hydrogel demands for 3D printing include: 1) preservation of the printed shape after the deposition; 2) maintaining cell viability and cell function and 3) easy handling of the printed construct. In this study we analyze the applicability of a novel, photosensitive hydrogel (Lutrol) for printing of 3D structured bone grafts. We benefit from the fast temperature-responsive gelation ability of thermosensitive Lutrol-F127, ensuring organized 3D extrusion, and the additional stability provided by covalent photocrosslinking allows handling of the printed scaffolds. We studied the cytotoxicity of the hydrogel and osteogenic differentiation of embedded osteogenic progenitor cells. After photopolymerization of the modified Lutrol hydrogel, cells remain viable for up to three weeks and retain the ability to differentiate. Encapsulation of cells does not compromise the mechanical properties of the formed gels and multilayered porous Lutrol structures were successfully printed.

  17. [Experimental implantation of hydrogel into bone].

    Science.gov (United States)

    Korbelár, P; Vacík, J; Dylevský, I; Sulc, J; Hulvert, J

    1989-02-01

    In spite of the rapid development of various natural and artifical implants of bone tissue, bones or whole joints, no material was found as yet which would maximally resemble the structure of the bone tissue and would also be maximally compatible. The present study deals with the application possibilities of unsoluble hydrophilic gels (hydrogels) as substitutes of bone tissue in experiment. The study concerns above all their biocompatibility with regard to the porous qualities of the implant and to its chemical structure, and evaluates their behaviour in the spongious and compact bone. It was used polyhydroxyethylmethacrylate (polyHEMA) which is crossling with small amount of glycoldimethacrylate when by changing of ratio monomer: water is possible obtain from homogeneous to macroporous structure of polymers. The macroporous structure was increased and the surface of the macroporous structure of polymers. The macroporous structure was increased and the surface of the macroporous, sinterted HEMA modified and implanted. The so-called double porosity was thus obtained. The implants were prepared in the form of cylinders (3.5 mm in diameter) in 8 different modifications and surgically implanted into the subtrochanteric and supracondylic part of the rabbit femurs. 42 animals were operated on. The obtained preparations were then evaluated macroscopically, and histologically processed in half-thin cuts (3-4 micrones). 124 samples were thus obtained. Some samples were radiographically contrasting. The rabbits were killed at intervals from 1-6 months, i.e. 32-193 days. It was found that the hydrogels modifications used in the experiment are biocompatible, their compatibility increasing in dependence on the increasing porosity. The non-porous and microporous hydrogels are not compatible and are damarked. The sintered macroporous gel is surrounded by a thin fibrine membrane signifying a high degree of compatibility with the bone tissue. By adding metacrylate acid to the

  18. Injectable bioadhesive hydrogels with innate antibacterial properties

    Science.gov (United States)

    Giano, Michael C.; Ibrahim, Zuhaib; Medina, Scott H.; Sarhane, Karim A.; Christensen, Joani M.; Yamada, Yuji; Brandacher, Gerald; Schneider, Joel P.

    2014-06-01

    Surgical site infections cause significant postoperative morbidity and increased healthcare costs. Bioadhesives used to fill surgical voids and support wound healing are typically devoid of antibacterial activity. Here we report novel syringe-injectable bioadhesive hydrogels with inherent antibacterial properties prepared from mixing polydextran aldehyde and branched polyethylenimine. These adhesives kill both Gram-negative and Gram-positive bacteria, while sparing human erythrocytes. An optimal composition of 2.5 wt% oxidized dextran and 6.9 wt% polyethylenimine sets within seconds forming a mechanically rigid (~\

  19. Hydrogels for osteochondral repair based on photocrosslinkable carbamate dendrimers.

    Science.gov (United States)

    Degoricija, Lovorka; Bansal, Prashant N; Söntjens, Serge H M; Joshi, Neel S; Takahashi, Masaya; Snyder, Brian; Grinstaff, Mark W

    2008-10-01

    First generation, photocrosslinkable dendrimers consisting of natural metabolites (i.e., succinic acid, glycerol, and beta-alanine) and nonimmunogenic poly(ethylene glycol) (PEG) were synthesized divergently in high yields using ester and carbamate forming reactions. Aqueous solutions of these dendrimers were photocrosslinked with an eosin-based photoinitiator to afford hydrogels. The hydrogels displayed a range of mechanical properties based on their structure, generation size, and concentration in solution. All of the hydrogels showed minimal swelling characteristics. The dendrimer solutions were then photocrosslinked in situ in an ex vivo rabbit osteochondral defect (3 mm diameter and 10 mm depth), and the resulting hydrogels were subjected to physiologically relevant dynamic loads. Magnetic resonance imaging (MRI) showed the hydrogels to be fixated in the defect site after the repetitive loading regimen. The ([G1]-PGLBA-MA) 2-PEG hydrogel was chosen for the 6 month pilot in vivo rabbit study because this hydrogel scaffold could be prepared at low polymer weight (10 wt %) and possessed the largest compressive modulus of the 10% formulations, a low swelling ratio, and contained carbamate linkages, which are more hydrolytically stable than the ester linkages. The hydrogel-treated osteochondral defects showed good attachment in the defect site and histological analysis showed the presence of collagen II and glycosaminoglycans (GAGs) in the treated defects. By contrast, the contralateral unfilled defects showed poor healing and negligible GAG or collagen II production. Good mechanical properties, low swelling, good attachment to the defect site, and positive in vivo results illustrate the potential of these dendrimer-based hydrogels as scaffolds for osteochondral defect repair.

  20. Blended Learning in Action: A Practical Guide toward Sustainable Change

    Science.gov (United States)

    Tucker, Catlin R.; Wycoff, Tiffany; Green, Jason T.

    2017-01-01

    Blended learning has the power to reinvent education, but transitioning to a blended model is challenging. Blended learning requires a fundamentally new approach to learning as well as a new skillset for both teachers and school leaders. Loaded with research, examples, and resources, "Blended Learning in Action" demonstrates the…

  1. Synthesis and characterization of antibacterial carboxymethylcellulose/CuO bio-nanocomposite hydrogels.

    Science.gov (United States)

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

    2015-02-01

    In this study, carboxymethyl cellulose/CuO nanocomposite hydrogels have been synthesized through the in situ formation of CuO nanoparticles within swollen carboxymethyl cellulose hydrogels. The aim of the study was to investigate whether these hydrogels have the potential to be used in antibacterial applications. The formation of CuO nanoparticles in the hydrogels was confirmed using X-ray diffraction and scanning electron microscopy studies. In addition, swelling behavior of nanocomposite hydrogels was investigated in various pH values and salt solutions. Furthermore, the CuO nanocomposite hydrogels were tested for antibacterial activities. The antibacterial activity of the nanocomposite hydrogels was studied by inhibition zone method against Escherichia coli and Staphylococcus aureus. The nanocomposite hydrogels demonstrated excellent antibacterial effects. Therefore, the developed carboxymethyl cellulose/CuO nanocomposite hydrogels can be used effectively for biomedical application.

  2. Green synthesis of tea Ag nanocomposite hydrogels via mint leaf extraction for effective antibacterial activity.

    Science.gov (United States)

    Jayaramudu, Tippabattini; Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Sadiku, E R; Mohana Raju, Konduru; Amalraj, John

    2017-10-01

    In this report, we investigated the swelling behavior and antibacterial property of nanosilver composite hydrogels made from tea with polyacrylamide via a free-radical polymerization and green process technique. This is probably for the first time; tea-based nano silver composite hydrogels were developed. The composite hydrogels comprise embedded nano silver particles in the tea hydrogel matrix via a green process with mint leaf extract. The size of the nano silver particles in the hydrogel matrix was found to be < 10 nm. The nano silver composite hydrogels formed and their blank hydrogels from the mint leaf were characterized by using ultraviolet-visible spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy, thermogravimetric analysis and X-ray diffraction studies. The nano silver composite hydrogels developed exhibit eminent antibacterial activity against Escherichia coli and Staphylococcus aureus. This clearly indicates that the nano silver composite hydrogels are potential candidates for antimicrobial applications.

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

    Science.gov (United States)

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

    2015-03-01

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

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

    Science.gov (United States)

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

    2015-10-28

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

  5. Relations between blended learning possibilities and teachers' approaches to blended learning

    DEFF Research Database (Denmark)

    Stenalt, Maria Hvid; Nielsen, Tobias Alsted; Bager-Elsborg, Anna

    Higher Education has embraced blended learning as a way of enhancing quality in teaching and helping students to learn. This presentation addresses relations between blended learning possiblities presented to teachers in a teacher training project and teachers’ approaches to blended learning. We...... suggest that in order to identify the level of impact of integrating technologies in teaching and learning, we need to understand the factors influencing approaches to design of courses for blended contexts. Participants in the teacher training project come from the Department of Law at Aarhus University......: • Optain locally-embedded knowledge about blended learning • Develop opportunities for law students to receive (more) feedback • Comply with strategic aims The results so far suggest that teachers provide a disciplinary perspective on the key dimensions of blended learning, which influences...

  6. 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.

  7. Three-dimensional biomimetic mineralization of dense hydrogel templates.

    Science.gov (United States)

    Liu, Gao; Zhao, Dacheng; Tomsia, Antoni P; Minor, Andrew M; Song, Xiangyun; Saiz, Eduardo

    2009-07-29

    An electric-current-assisted method was used to mineralize dense hydrogels and create hydroxyapatite/hydrogel composites with unique hierarchical structures. The microstructure of the final material can be controlled by the mineralization technique and the chemistry of the organic matrix. A hydroxyapatite/hydrogel composite was obtained with a large inorganic content (approximately 60% of the weight of the organics). After being heated to 1050 degrees C, the sintered inorganic phase has a very uniformly distributed porosity and its Brunauer-Emmett-Teller (BET) surface area is 0.68 m(2)/g.

  8. Microscale Strategies for Generating Cell-Encapsulating Hydrogels

    Directory of Open Access Journals (Sweden)

    Ali Khademhosseini

    2012-09-01

    Full Text Available Hydrogels in which cells are encapsulated are of great potential interest for tissue engineering applications. These gels provide a structure inside which cells can spread and proliferate. Such structures benefit from controlled microarchitectures that can affect the behavior of the enclosed cells. Microfabrication-based techniques are emerging as powerful approaches to generate such cell-encapsulating hydrogel structures. In this paper we introduce common hydrogels and their crosslinking methods and review the latest microscale approaches for generation of cell containing gel particles. We specifically focus on microfluidics-based methods and on techniques such as micromolding and electrospinning.

  9. Anion-Responsive Metallopolymer Hydrogels for Healthcare Applications

    Science.gov (United States)

    Zhang, Jiuyang; Yan, Jing; Pageni, Parasmani; Yan, Yi; Wirth, Adam; Chen, Yun-Ping; Qiao, Yali; Wang, Qian; Decho, Alan W.; Tang, Chuanbing

    2015-01-01

    Metallopolymers combine a processable, versatile organic polymeric skeleton with functional metals, providing multiple functions and methodologies in materials science. Taking advantage of cationic cobaltocenium as the key building block, organogels could be simply switched to hydrogels via a highly efficient ion exchange. With the unique ionic complexion ability, cobaltocenium moieties provide a robust soft substrate for recycling antibiotics from water. The essential polyelectrolyte nature offers the metallopolymer hydrogels to kill multidrug resistant bacteria. The multifunctional characteristics of these hydrogels highlight the potential for metallopolymers in the field of healthcare and environmental treatment. PMID:26202475

  10. ON SWELLING CHARACTERISTICS AND MECHANISM OF TEMPERATURE SENSITIVE HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    YU Xisheng; TONG Shuixin; SUN Yishi

    1990-01-01

    A series of N-substituted acrylamide monomers and the temperature sensitive hydrogels of their copolymer with N, N ' methylene-bis -acrylamide (Bis) have been synthesized. The effects of monomer structures, composition of the initial monomer mixture, polymerization temperature, the extent of ionization of the network and the presence of acid, base, salt or organic compound on the formation and the swelling characteristics of the temperature sensitive hydrogels have been systematically studied. The mechanism of the temperature sensitive phase transformation of the hydrogels was also investigated.

  11. Morphology Evolution of Polycarbonate-Polystyrene Blends During Compounding

    DEFF Research Database (Denmark)

    Chuai, Chengzhi; Almdal, Kristoffer; Johannsen, Ib;

    2001-01-01

    The morphology evolution of polycarbonate-polystyrene (PC/PS) blends during the compounding process in three blending methods of industrial relevance, namely melt blending, re-melt blending in a twin-screw extruder and tri-melt blending in an injection-moulding machine, was investigated using......-empirical model. The results show that the formation of co-continuous morphology strongly depends on blend composition and melt blending method, whereas the model prediction for phase inversion deviates from the experimental values. Further, we found that the initial mechanism of morphology evolution involves...

  12. Lipogels: surface-adherent composite hydrogels assembled from poly(vinyl alcohol) and liposomes

    Science.gov (United States)

    Jensen, Bettina E. B.; Hosta-Rigau, Leticia; Spycher, Philipp R.; Reimhult, Erik; Städler, Brigitte; Zelikin, Alexander N.

    2013-07-01

    illustrating the potential of the lipogels as a drug eluting interface for biomedical applications. Electronic supplementary information (ESI) available: Paclitaxel calibration curve and images of DIC of PLL blended PVA physical hydrogels, lipogel FRAP, and different cell lines attached to lipogels are available. See DOI: 10.1039/c3nr01662e

  13. Chronic ethanol intake modifies pyrrolidon carboxypeptidase activity in mouse frontal cortex synaptosomes under resting and K+ -stimulated conditions: role of calcium.

    Science.gov (United States)

    Mayas, María Dolores; Ramírez-Expósito, María Jesús; García-López, María Jesús; Carrera, María Pilar; Martínez-Martos, José Manuel

    2008-07-04

    Pyrrolidon carboxypeptidase (Pcp) is an omega peptidase that removes pyroglutamyl N-terminal residues of peptides such as thyrotrophin-releasing hormone (TRH), which is one of the neuropeptides that has been localized into many areas of the brain and acts as an endogenous neuromodulator of several parameters related to ethanol (EtOH) consumption. In this study, we analysed the effects of chronic EtOH intake on Pcp activity on mouse frontal cortex synaptosomes and their corresponding supernatant under basal and K+ -stimulated conditions, in presence and absence of calcium (Ca2+) to know the regulation of Pcp on TRH. In basal conditions, chronic EtOH intake significantly decreased synaptosomes Pcp activity but only in absence of Ca2+. However, supernatant Pcp activity is also decreased in presence and absence of calcium. Under K+-stimulated conditions, chronic EtOH intake decreased synaptosomes Pcp activity but only in absence of Ca2+, whereas supernatant Pcp activity was significantly decreased only in presence of Ca2+. The general inhibitory effect of chronic EtOH intake on Pcp activity suggests an inhibition of TRH metabolism and an enhancement of TRH neurotransmitter/neuromodulator functions, which could be related to putative processes of tolerance to EtOH in which TRH has been involved. Our data may also indicate that active peptides and their degrading peptidases are released together to the synaptic cleft to regulate the neurotransmitter/neuromodulator functions of these peptides, through a Ca2+ -dependent mechanism.

  14. Influence of water dilution on percutaneous absorption of N-vinyl-2-pyrrolidone in vivo and ex vivo in rats and ex vivo in humans.

    Science.gov (United States)

    Marquet, Fabrice; Payan, Jean-Paul; Beydon, Dominique; Wathier, Ludivine; Ferrari, Elisabeth; Grandclaude, Marie-Christine

    2015-11-01

    N-vinyl-2-pyrrolidone (NVP) is mainly used as a monomer in the production of polyvinylpyrrolidone or copolymers. Percutaneous absorption is an important source of exposure in the work environment. However, few studies have investigated this route of absorption. In this study, percutaneous absorption of neat or aqueous NVP solutions was measured in vivo and ex vivo in rats, and ex vivo in humans. Penetration and absorption fluxes were very similar following in vivo exposure to neat NVP (0.54 and 0.43 mg/cm(2)/h, respectively). Exposing rats to a 50% aqueous solution of NVP increased both fluxes threefold (to 1.48 and 1.55 mg/cm(2)/h, respectively). Ex vivo, the absorption flux increased with solutions from 10 to 25% of NVP, reached a plateau (between 25 and 50% in rat, 25 and 75% in human) and then decreased with neat NVP. In vivo and ex vivo absorption fluxes measured using rat skin were similar, supporting the hypothesis that the ex vivo measurements were a good representation of what was observed in vivo. Thus, for humans, the ex vivo measurements are likely the same as would be determined in vivo.

  15. Chain length effect on dynamical structure of poly(vinyl pyrrolidone)–polar solvent mixtures in dilute solution of dioxane studied by microwave dielectric relaxation measurement

    Indian Academy of Sciences (India)

    R J Sengwa; Sonu Sankhila

    2006-08-01

    Dielectric relaxation study of the binary mixtures of poly(vinyl pyrrolidone) (PVP) (Mw = 24000, 40000 and 360000 g mol-1) with ethyl alcohol (EA) and poly(ethylene glycol)s (PEGs) (Mw = 200 and 400 g mol-1) in dilute solutions of dioxane were carried out at 10.1 GHz and 35°} C. The relaxation time of PVP–EA mixtures was interpreted by the consideration of a wait-and-switch model in the local structure of self-associated ethyl alcohol molecules and also the PVP chain length as a geometric constraint for the reorientational motion of ethyl alcohol molecules. The formation of complexes and effect of PVP chain length on the molecular dynamics, chain flexibility and stretching of PEG molecules in PVP–PEG mixtures were explored from the comparative values of dielectric relaxation time. Further, relaxation time values in dioxane and benzene solvent confirm the viscosity independent molecular dynamics in PVP–EA mixtures but the values vary significantly with the non-polar solvent environment.

  16. Preparation and surface properties of mesoporous silica particles modified with poly(N-vinyl-2-pyrrolidone) as a potential adsorbent for bilirubin removal

    Energy Technology Data Exchange (ETDEWEB)

    Timin, Alexander, E-mail: a_timin@mail.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); Rumyantsev, Evgeniy, E-mail: evr@isuct.ru [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); Lanin, Sergey N., E-mail: SNLanin@phys.chem.msu.ru [Chemistry Department, Physical Chemistry Division, Lomonosov Moscow State University, 1-3 Leninskie Gory, 119991 Moscow (Russian Federation); Rychkova, Sveta A. [Chemistry Department, Physical Chemistry Division, Lomonosov Moscow State University, 1-3 Leninskie Gory, 119991 Moscow (Russian Federation); Guseynov, Sabir S. [Krestov Institute of Solution Chemistry of Russian Academy of Sciences, 153000 Ivanovo (Russian Federation); Solomonov, Alexey V. [Inorganic Chemistry Department, Ivanovo State University of Chemistry and Technology (ISUCT), 7, Sheremetevsky prosp., 153000 Ivanovo (Russian Federation); Antina, Elena V. [Krestov Institute of Solution Chemistry of Russian Academy of Sciences, 153000 Ivanovo (Russian Federation)

    2014-10-15

    The surface of silica particles was modified with polyvinyl pyrrolidone (PVP) through sol–gel process. The different experimental techniques, i.e., thermogravimetric analysis (TGA and DTG), nitrogen adsorption, scanning electron microscopy (SEM), laser diffraction analysis (LDA), fourier transform spectroscopy (FTIR) are used to characterize the pure non-functionalized and functionalized silicas containing different amount of PVP. It was shown that PVP-modified silica samples have well developed porous structure; the values of specific surface area for PVP-modified silicas are in the range of 140–264 m{sup 2} g{sup −1}. While the non-functionalized silica shows the low surface area (S{sub BET} = 40 m{sup 2} g{sup −1}). The BJH analysis showed that PVP can be used as an effective agent to increase an average pore size and total pore volume. The results indicate that PVP functionalized silicas show a potential as effective adsorbents for bilirubin removal compared to other available adsorbents. - Highlights: • PVP functionalized silicas were synthesized via sol–gel method. • Modification of silica by PVP leads to the formation of mesoporous structure. • PVP functionalized mesoporous silicas demonstrate good adsorption properties for bilirubin removal.

  17. Effect of poly(vinyl pyrrolidone) on the morphology and physical properties of poly(vinyl alcohol)/sodium montmorillonite nanocomposite films

    Institute of Scientific and Technical Information of China (English)

    Dibyendu Mondal; Md. Masud R. Mollick; Biplab Bhowmick; Dipanwita Maity; Mrinal K. Bain; Dipak Rana; Asis Mukhopadhyay; Kausik Dana; Dipankar Chattopadhyay

    2013-01-01

    Nanocomposites of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP) and sodium montmorillonite (NaþMMT) were prepared by solution mixing and then cast into films. X-ray diffraction analysis and images of transmission electron microscopy establish the formation of PVA/NaþMMT intercalated nanocomposite. Exfoliated and highly intercalated PVA/PVP/NaþMMT nanocomposite formed in the presence of PVP. Inclusion of PVP in PVA/NaþMMT matrix enhances the hydrogen bonding interactions between PVA and NaþMMT and thus increases the mechanical properties and thermal stability of PVA/PVP/NaþMMT nanocomposites compared to PVA/NaþMMT nanocomposite. The interactions between PVA, PVP and NaþMMT were established by the Fourier transform infrared spectroscopy. The moisture absorption tendency of both the PVA and PVA/PVP films reduced after the incorporation of NaþMMT at 75% constant relative humidity. Differential scanning calorimetry studies show that the presence of PVP and NaþMMT both are responsible for reducing the heat of fusion, and crystallinity of PVA. The flow behavior of the PVA, PVA/PVP and its nanocomposite solutions has been also studied. Water vapor permeability of PVA/PVP/NatMMT composite films decreased in the presence of nanoclay due to increasing tortuous paths for diffusion.

  18. Radiation synthesized poly(n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles as LSPR-based optical sensor for mercury ions estimation

    Energy Technology Data Exchange (ETDEWEB)

    Misra, Nilanjal; Kumar, Virendra, E-mail: vkrawat75@gmail.com, E-mail: vkumar@barc.gov.in; Goel, Narender Kumar; Varshney, Lalit [Bhabha Atomic Research Centre, Radiation Technology Development Division (India)

    2015-07-15

    Poly(n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles (PVP-Au-NPs) have been synthesized via a green-{sup 60}Co-Gamma radiolytic route and employed as a localized surface plasmon resonance (LSPR)-based optical sensor for estimation of trace quantities of Hg{sup 2+} ion in aqueous solutions. The in situ generated PVP-Au-NPs were characterized using UV–vis spectroscopy, transmission electron microscopy, and particle size analysis techniques. Reaction conditions were optimized to obtain uniformly dispersed PVP-Au-NPs with average particle size of 7.1 ± 1.6 nm (±s), which exhibited a narrow LSPR band at ∼527 nm. The decrease in LSPR band intensity of PVP-Au-NPs with increase in Hg{sup 2+} ion concentration was found to be linear in the Hg{sup 2+} ion concentration range of 0–100 nM. The LSPR-based PVP-Au-NPs optical sensor system was found to be selective for Hg{sup 2+} and independent of interference from other metal ions such as Ca{sup 2+,} Cu{sup 2+}, Cd{sup 2+}, and Fe{sup 2+} up to a concentration of 500 nM.

  19. Fabrication and characterization of superparamagnetic poly(vinyl pyrrolidone)/poly(L-lactide)/Fe{sub 3}O{sub 4} electrospun membranes

    Energy Technology Data Exchange (ETDEWEB)

    Savva, Ioanna; Constantinou, Demetris [University of Cyprus, Department of Mechanical and Manufacturing Engineering, Nicosia (Cyprus); Marinica, Oana [National Center for Engineering of Systems with Complex Fluids, University “Politehnica” Timisoara, Timisoara (Romania); Vasile, Eugeniu [METAV Research and Development, Bucharest (Romania); Vekas, Ladislau [Center for Fundamental and Advanced Technical Research, Romanian Academy, Timisoara Branch, Timisoara (Romania); Krasia-Christoforou, Theodora, E-mail: krasia@ucy.ac.cy [University of Cyprus, Department of Mechanical and Manufacturing Engineering, Nicosia (Cyprus)

    2014-02-15

    The fabrication of magnetoactive fibrous nanocomposite membranes based on poly(vinyl pyrrolidone) (PVP), poly(L-lactide) (PLLA) and pre-formed oleic acid coated magnetite nanoparticles (OA Fe{sub 3}O{sub 4}) is presented. The aforementioned materials have been prepared by means of the electrospinning technique following a single-step fabrication process. The PVP/PLLA/OA Fe{sub 3}O{sub 4} nanocomposite membranes were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that provided information on the fiber diameters as well as on the morphological and dimensional characteristics of the OA Fe{sub 3}O{sub 4} nanoparticles embedded within the fibers. The thermal stability of these materials was evaluated by means of thermal gravimetric analysis (TGA) measurements. Finally, vibrational sample magnetometry (VSM) analysis disclosed superparamagnetic behavior at room temperature. The combination of the hydrophilic, biocompatible and photo-crosslinkable PVP with the biodegradable PLLA and the superparamagnetic OA Fe{sub 3}O{sub 4} nanoparticles within these materials allows for the future development of crosslinked fibrous magnetoactive nanocomposites exhibiting high stability in aqueous solutions, with potential use in biomedical and environmental applications. - Highlights: • Fabrication and characterization of electrospun fibrous membranes. • PVP and PVP/PLLA membranes. • PVP/PLLA/Fe{sub 3}O{sub 4} magnetoactive nanocomposite membranes. • Tunable superparamagnetic behavior at room temperature.

  20. Fumaric acid monoethyl ester-functionalized poly(D,L-lactide)/N-vinyl-2-pyrrolidone resins for the preparation of tissue engineering scaffolds by stereolithography.

    Science.gov (United States)

    Jansen, Janine; Melchels, Ferry P W; Grijpma, Dirk W; Feijen, Jan

    2009-02-01

    Polymer networks were prepared by photocross-linking fumaric acid monoethyl ester (FAME) functionalized, three-armed poly(D,L-lactide) oligomers using N-vinyl-2-pyrrolidone (NVP) as diluent and comonomer. The use of NVP together with FAME-functionalized oligomers resulted in copolymerization at high rates, and networks with gel contents in excess of 90% were obtained. The hydrophilicity of the poly(D,L-lactide) networks increases with increasing amounts of NVP, networks containing 50 wt % of NVP absorbed 40% of water. As the amount of NVP was increased from 30 to 50 wt %, the Young's modulus after equilibration in water decreased from 0.8 to 0.2 GPa, as opposed to an increase from 1.5 to 2.1 GPa in the dry state. Mouse preosteoblasts readily adhered and spread onto all prepared networks. Using stereolithography, porous structures with a well-defined gyroid architecture were prepared from these novel materials. This allows the preparation of tissue engineering scaffolds with optimized pore architecture and tunable material properties.