Yazar "Saraydin, D" seçeneğine göre listele

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    Immobilization of Saccharomyces cerevisiae on to acrylamide-sodium acrylate hydrogels for production of ethyl alcohol
    (Elsevier Science Inc, 2003) Öztop, HN; Öztop, AY; Karadag, E; Isikver, Y; Saraydin, D
    Acrylamide/sodium acrylate (AAm/SA) copolymers, prepared by using various crosslinkers, were used in experiments on swelling, diffusion, immobilization of yeast cells (Saccharomyces cerevisiae) and production of ethyl alcohol. AAm/SA hydrogels were used for swelling and diffusion studies in the nutrient medium of the cells. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, diffusional exponent, network constant and diffusion coefficient of the hydrogel/penetrant systems were calculated and evaluated. Yeast cells were immobilized onto the hydrogels by adsorption method during multiplication and ethyl alcohol production of the hydrogels was investigated. Swelling of AAm increased with the addition of SA and ethyl alcohol production increased with increasing SA in the hydrogels. The best system for immobilization is found to be AAm/SA hydrogels containing N,N'-methylenebisacrylamide as crosslinker. (C) 2002 Elsevier Science Inc. All rights reserved.
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    In vivo biocompatibility of radiation crosslinked acrylamide copolymers
    (Elsevier Science Bv, 2004) Saraydin, D; Ünver-Saraydin, S; Karadag, E; Koptagel, E; Güven, O
    In vitro swelling and in vivo biocompatibility of radiation crosslinked acrylamide copolymers such as acrylamide/crotonic acid (AAm/CA) and acrylamide/itaconic acid (AAm/IA) were studied. The swelling kinetics of acrylamide copolymers were performed in distilled water, human serum and some simulated physiological fluids such as phosphate buffer, pH 7.4, glycine-HCl buffer, pH 1.1, physiological saline solution, and some swelling and diffusion parameters have been calculated. AAm/CA and AAm/IA hydrogels were subcutaneously implanted in rats for up to 10 weeks and the immediate short- and long-term tissue response to these implants were investigated. Histological analysis indicated that tissue reaction at the implant site progressed from an initial acute inflammatory response. No necrosis, tumorigenesis or infection was observed at the implant site up to 10 weeks. The radiation crosslinked AAm/CA and AAm/IA copolymers were found well tolerated, non-toxic and highly biocompatible. However, AAm/IA copolymer was not found to be compatible biomaterials, because one of the AAm/IA samples was disintegrated into small pieces in the rat. (C) 2003 Elsevier B.V. All rights reserved.
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    PH-sensitive chitosan films for baker's yeast immobilization
    (Humana Press Inc, 2002) Öztop, HN; Saraydin, D; Çetinus, S
    Dried baker's yeast cells were immobilized on a chitosan film, which is a natural polymer. Prepared chitosan films were treated with glutaraldehyde to facilitate the immobilization of the cells. The effects of the amount of glutaraldehyde, incubation time, pH, and temperature on immobilization were investigated. The amount of glutaraldehyde was chosen to be 0.01% (weight). The highest amount of yeast immobilization was obtained with 5 h incubation. It was determined that optimum temperature for immobilization is 25degreesC, and the optimum pH for immobilization is 6. Immobilized cells were allowed to stand for 3 d in distilled water and buffer solution (pH 6) to investigate the desorption, but no desorption was found. The maximum immobilization capacities were found to be 90 mug protein cm(-2) film in optimum conditions.
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    Radiation crosslinked poly(acrylamide/2-hydroxypropyl methacrylate/maleic acid) and their usability in the uptake of uranium
    (Taylor & Francis Inc, 2002) Saraydin, D; Solpan, D; Isikver, Y; Ekici, S; Güven, O
    The terpolymeric poly(acrylamide/2-hydroxy propylmethacrylate/maleic acid) (AAm/HPMA/MA) hydrogels in the rod form have been prepared by gamma radiation of quaternary mixtures of acrylamide/2-hydroxy propylmethacrylate/ maleic acid/water. Spectroscopic and thermal analyses of AAm/HPMA/MA were made. The hydrogels were used in experiments on swelling, diffusion and adsorptions of uranyl ions from aqueous uranyl acetate solutions. For the hydrogels, the parameters of swelling and diffusion were calculated. In the experiment of uranyl ions adsorption, Type L (Langmuir) adsorption isotherm in Giles classification system was found. Binding parameters such as the initial binding constant (K-i), the equilibrium binding constant (K), monolayer coverage (n), site-size (u), maximum fractional occupancy (theta) were calculated for hydrogel/uranyl ion system by using the linearization methods such as Klotz, Scatchard and Langmuir methods. Thermodynamic parameters such as adsorption free energy (DeltaG), adsorption enthalpy (DeltaH) and adsorption entropy (DeltaS) were also calculated. Finally, the effect of MA contents of the hydrogel and irradiation doses was Studied on the adsorption of uranyl ion from its aqueous solution.
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    Synthesis, characterization and evaluation of IPN hydrogels for antibiotic release
    (Taylor & Francis Inc, 2004) Ekici, S; Saraydin, D
    We prepared new ternary interpenetrating polymeric networks (IPN) systems containing chitosan, poly(N-vinylpyrrolidone) and poly(acrylamide) polymers. IPNs were synthesized by radical polymerization of acrylamide monomers in presence of glutaraldehyde (G) and N,N'-methylenebisacrylamide as crosslinkers and the other polymers. These IPNs were named as C-P-A. Glutaraldehyde were used in different concentration to control the network porous of IPNs. Spectroscopic and thermal analyses of these cylindrical shaped IPNs were made with fourier transform infrared spectroscopy analysis, thermogravimetric analysis, and thermomechanical analysis. Swelling studies of IPNs were carried out at pH 1.1 and pH 7.4 at 37degreesC. The swelling and diffusion parameters of IPNs in these solutions were calculated. Amoxicillin as a bioactive species was entrapped to the IPNs during synthesis. In vitro release kinetics of IPNs were investigated. The experimental data of swelling and release studies suggest clearly that the swelling and release process obeys second-order kinetics. The release of the entrapped bioactive species from IPNs depends on the degree of crosslinking of the polymer and pH of the medium at body temperature. We observed that amoxicillin release at pH 1.1 was higher than at pH 7.4. As a result, IPNs-based chitosan with different cross-linker concentration could be promising candidates for formulation in oral gastrointestinal delivery systems.
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    Water uptake in chemically crosslinked poly(acrylamide-co-crotonic acid) hydrogels
    (Elsevier Sci Ltd, 2005) Karadag, E; Üzüm, ÖB; Saraydin, D
    The aim of this study was to investigate that swelling capability of acrylamide (AAm) hydrogels by adding hydrophilic co-monomer such as crotonic acid (CA). Superswelling poly(acrylamide/crotonic) acid, poly(AAm-co-CA) hydrogels were prepared by free radical polymerization in aqueous solution of AAm with CA. For each copolymerization, four different composition of CA and a concentration of multifunctional crosslinkers such as ethylene glycol dimethacrylate (EGDMA) and N,N ''-methylenebisacrylamide (NMBA) were used. Equilibrium swelling, some swelling kinetics parameters such as the initial swelling rate, swelling rate constant, theoretical equilibrium swelling and diffusional parameters such as swelling exponent, swelling constant and diffusion coefficients of hydrogels have been determined by swelling studies. At the end of dynamic swelling tests, relative content of CA on the swelling properties were examined. It has seen that, if CA contents were increased, equilibrium swelling of the hydrogels were higher than. Poly (AAm-co-CA) hydrogels were swollen in the range 1843-2577% in water, while poly(AAm) hydrogels swelled as 1729-1798%. Equilibrium water content of poly(AAm-co-CA) hydrogels were calculated in the range 0.9473-0.9626. Swelling exponents of poly (AAm-co-CA) hydrogels has calculated as 0.58-0.69. Water intake of hydrogels followed a non-Fickian type diffusion. (c) 2004 Elsevier Ltd. All rights reserved.