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Öğe Affinity dye-ligand poly(hydroxyethyl methacrylate)/chitosan composite membrane for adsorption lysozyme and kinetic properties(Elsevier Science Sa, 2003) Bayramoglu, G; Yilmaz, M; Arica, MYA composite membrane from 2-hydroxyethyl methacrylate (HEMA) and poly(hydroxyethyl methacrylate)/chitosan (pHEMA/chitosan) was synthesized via UV initiated photo-polymerization in the presence of an initiator alpha,alpha'-azoisobutyronitrile (AIBN). Procion Brown MX 5BR was then covalently immobilized onto composite membrane as a dye-ligand. The binding characteristics of a model protein (i.e. lysozyme) to the dye-ligand immobilized affinity membrane have been investigated from aqueous solution using the plain composite membrane as a control system. The experimental data was analyzed using two adsorption kinetic models, the pseudo-first-order and the pseudo-second-order, to determine the best-fit equation for the adsorption of lysozyme onto affinity composite membrane. The second-order equation for the adsorption of lysozyme on the dye-ligand membrane systems is the most appropriate equation to predict the adsorption capacity for the affinity membrane. The reversible lysozyme adsorption on the affinity membrane obeyed the Freundlich isotherm. The lysozyme adsorption capacity of the plain membrane and the dye-ligand affinity membrane were 8.3 and 121.5 mg ml(-1), respectively. (C) 2002 Elsevier Science B.V. All rights reserved.Öğe Affinity membrane chromatography: relationship of dye-ligand type to surface polarity and their effect on lysozyme separation and purification(Elsevier, 2004) Arica, MY; Yilmaz, M; Yalcin, E; Bayramoglu, GTwo different dye-ligands, i.e. Procion Brown MX-5BR (RB-10) and Procion Green H-4G (RG-5) were immobilised onto poly(2-hydroxyethylmethacrylate) (pHEMA) membranes. The polarities of the affinity membranes were determined by contact angle measurements. Separation and purification of lysozyme from solution and egg white were investigated. The adsorption data was analysed using two adsorption kinetic models the first order and the second order to determine the best-fit equation for the separation of lysozyme using affinity membranes. The second-order equation for the adsorption of lysozyme on the RB-10 and RG-5 immobilised membranes systems is the most appropriate equation to predict the adsorption capacity for the affinity membranes. The reversible lysozyme adsorption on the RB-10 and RG-5 did not follow the Langmuir model, but obeyed the Temkin and Freundlich isotherm model. Separation and purification were monitored by determining the lysozyme activity using Micrococcus lysodeikticus as substrate. The purities of the eluted lysozyme, as determined by HPLC, were 76 and 92% with recovery 63 and 77% for RB-10 and RG-5 membranes, respectively. For the separation and purification of lysozyme the RG-5 immobilised membrane provided the best results. The affinity membranes are stable when subjected to sanitization with sodium hydroxide after repeated adsorption-elution cycles. (C) 2004 Elsevier B.V. All rights reserved.Öğe Biosorption of Hg2+, Cd2+, and Zn2+ by Ca-alginate and immobilized wood-rotting fungus Funalia trogii(Elsevier, 2004) Arica, MY; Bayramoglu, G; Yilmaz, M; Bektas, S; Genc, OFunalia trogii biomass was immobilized in Ca-alginate gel beads. The live and beat inactivated immobilized forms were used for the biosorption of Hg2+, Cd2+ and Zn2+ ions by using plain Ca-alginate gel beads as a control system. The effect of pH was investigated and the maximum adsorption of metal ions on the Ca-alginate and both live and inactivated immobilized fungal preparations were observed at pH 6.0. The temperature change between 15 and 45 degreesC did not affect the biosorption capacity. The biosorption of Hg2+, Cd2+ and Zn2+ ions on the Ca-alginate beads and on both immobilized forms was studied in aqueous solutions in the concentration range of 30-600 mg/L. The metal biosorption capacities of the heat inactivated immobilized E trogii for Hg2+, Cd2+ and Zn2+ were 403.2, 191.6, and 54.0 mg/g, respectively, while Hg2+, Cd2+ and Zn2+ biosorption capacities of the immobilized live form were 333.0, 164.8 and 42.1 mg/g, respectively. The same affinity order on a molar basis was observed for single or multi-metal ions (Hg2+ > Cd2+ > Zn2+). The Langmuir and the Freundlich type models were found to exhibit good fit to the experimental data. The experimental data were analyzed using the first-order (Langergren equations) and the second order (Ritchie equations). The experimental biosorption capacity with time is found to be best fit the second-order equations. The alginate-fungus system could be regenerated by washing with a solution of hydrochloride acid (10 mM). The percent desorption achieved was as high as 97. The biosorbents were reused in five biosorption-desorption cycles without significant loss of their initial biosorption capacity. (C) 2004 Elsevier B.V. All rights reserved.Öğe Evaluation of lysozyme adsorptive behaviour of pHEMA-based affinity membranes related to the surface energy and its components to be used in chromatographic fields(Elsevier, 2004) Bayramoglu, G; Yilmaz, M; Arica, MYWe have studied the influence of the surface energy and its components of two different dye-ligand immobilised poly(hydroxyethylmethacrylate) (pHEMA) membranes to the adsorption of a protein "lysozyme" from aqueous solutions. For this purpose, macroporous pHEMA membranes were prepared by UV-initiated photo-polymerisation. Two different affinity dye-ligands (i.e. Reactive Brown-10 (RB-10) and Reactive Green-5 (RG-5)) were immobilised onto pHEMA membranes. The adsorption of lysozyme on the affinity membranes was carried out from solutions in the concentration range 0.05-3.00 mg/ml. The measurements of the contact angle for water, glycerol, formamide, diiodomethane (DIM), ethylene glycol and dimethylsulphoxide (DMSO) on plain, both RB-10 and RG-5 immobilised and their lysozyme covered counterpart pHEMA membranes were made. In accordance to the Young equation, the smaller the surface tension of the test liquid, the smaller becomes the contact angle measured on the membrane samples surfaces. The highest contact angles were obtained with water, whereas DMSO gave the lowest contact angles for all the tested membranes. The surface energy parameters of the investigated membranes were calculated from the measured contact angle values, using the mostly used three methods (i.e. the harmonic mean by Wu, the geometric mean by Fowkes and acid-base by van Oss). The adsorption of lysozyme significantly changed both the contact angles and component of surface free energy. It was found that the immobilisation of both dye-ligand increased the lysozyme adsorption capacity of the affinity membranes most significant, although there is not very large difference of surface energy between plain and both dye-ligand immobilised pHEMA membranes. (C) 2004 Elsevier B.V. All rights reserved.Öğe Surface properties of Reactive Yellow 2 immobilised pHEMA and HEMA/chitosan membranes: characterisation of their selectivity to different proteins(Elsevier, 2004) Arica, MY; Yilmaz, M; Yalcin, E; Bayramoglu, GPoly(hydroxyethyl methacrylate), pHEMA, and a composite pHEMA/chitosan networks were synthesized in the membrane form via UV initiated photo-polymerisation in the presence of an initiator alpha,alpha'-azoisobutyronitrile. Reactive Yellow 2 (RY-2) was covalently immobilised as a dye-ligand onto both membranes. The polarity and surface energy of the investigated membranes were determined by contact angle measurement. The incorporation of chitosan in the pHEMA networks produced more hydrophilic surface, as indicated by contact angle analysis. The binding characteristics of lysozyme, gamma-globulins, human serum albumin (HSA) and bovine serum albumin (BSA) to pHEMA-RY-2 and pHEMA/chitosan-RY-2 affinity membranes have been investigated from aqueous solution and their dye-ligand free forms were used as control systems. When chitosan was incorporated in the pHEMA network as a cationic polymer led to higher adsorption capacity for the lysozyme. Selective adsorption behaviour was also observed in the case of pHEMA/chitosan-RY-2 membrane for the lysozyme. The non-specific adsorptions of the lysozyme on the pHEMA and pHEMA/chitosan membranes were about 1.9 and 7.2 mg/ml, respectively. These were negligible for all others investigated proteins. The lysozyme adsorption data was analysed using the first-order and the second-order models. The first-order equation in both affinity membrane systems is the most appropriate equation to predict the adsorption capacities of the adsorbents. The adsorption isotherms well fitted the combined Langmuir-Freundlich model. A theoretical analysis has been conducted to estimate the thermodynamic contributions (changes in enthalpy, entropy and Gibbs free energy) for the adsorption of lysozyme to both dye-ligand immobilised membranes. The adsorption capacities of both dye-ligand immobilised membranes increased with increasing the temperature while decreased with increasing the NaCl concentration. Both affinity membranes are stable when subjected to sanitization with sodium hydroxide after repeated separation-elution cycles. (C) 2004 Elsevier B.V. All rights reserved.
