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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 heavy metal ions on immobilized white-rot fungus Trametes versicolor(Elsevier, 2003) Bayramoglu, G; Bektas, S; Arica, MYTrametes versicolor mycelia were immobilized in carboxymethylcellulose, CMC, beads via entrapment, and the bead containing immobilized fungus spores were incubated at 30 degreesC for 3 days to attain uniform growth on the bead surface. After incubation, the live and heat inactivated immobilized fungus on the CMC beads were used for the biosorption of Cu2+, Pb2+ and Zn2+ ions. Plain CMC beads were used as a control system. The biosorption of Cu2+, Pb2+ and Zn2+ ions by the CMC and both live and inactivated immobilized preparations increased as the initial concentration of Cu2+, Pb2+ and Zn2+ ions in the medium increased. The maximum biosorption capacities for both immobilized live and heat inactivated Trametes versicolor were 1.51 and 1.84 mmol Cu2+, 0.85 and 1.11 mmol Pb2+ and 1.33 and 1.67 mmol Zn2+ per g of dry biosorbents, respectively. Biosorption equilibrium was established in about 1.0h and the equilibrium was well described by Langmuir and Freundlich isotherms. A temperature change in the range of 15-45 degreesC did not affect the biosorption capacity. The affect of pH was also investigated and the maximum adsorption of Cu2+, Pb2+ and Zn2+ ions on the CMC and both live and inactivated immobilized fungal biomass was observed between pH 4.0 and 6.0. The CMC beads with the immobilized fungus can be regenerated using 10 mM HCl, with up to 97% recovery of the metal ions; the biosorbents reused up to five biosorption-desorption cycles without any major loss in the biosorption capacity. (C) 2003 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 Characterisation of tyrosinase immobilised onto spacer-arm attached glycidyl methacrylate-based reactive microbeads(Elsevier Sci Ltd, 2004) Arica, MY; Bayramoglu, G; Bicak, NImmobilisation of tyrosinase onto modified poly(methyl methacrylate-glycidyl methacrylate-divinyl benzene), poly(MMA-GMA-DVB), microbeads was studied. The epoxy group containing poly(MMA-MMA-DVB) microbeads were prepared by suspension polymerisation. The epoxy groups of the poly(MMA-GMA-DVB) microbeads was converted into amino groups with either ammonia or 1,6-diaminohexane (i.e., spacer-arm). Tyrosinase was then covalently immobilised on aminated and the spacer-arm-attached poly(MMA-GMA-DVB) microbeads using glutaric dialdehyde as a coupling agent. Incorporation of the spacer-arm resulted an increase in the apparent activity of the immobilised tyrosinase with respect to the enzyme immobilised on the aminated microbeads. The activity yield of the immobilised tyrosinase on the spacer-arm-attached poly(MMA-GMA-DVB) microbeads was 68%, and this was 51% for the enzyme, which was immobilised on the aminated microbeads. Both immobilised tyrosinase preparation has resistance to temperature inactivation as compared to that of the free form. The temperature profiles were broader for both immobilised preparations than that of the free enzyme. Kinetic parameters were determined for immobilised tyrosinase preparations as well as for the free enzyme. The values of the Michaels constants (K-m) for all the immobilised tyrosinase preparations were significantly larger, indicating decreased affinity by the enzyme for its substrate, whereas V-max values were smaller for the both immobilised tyrosinase preparations. In a 40 h continuous operation with spacer-arm-attached poly(MMA-GMA-DVB) microbeads at 30degreesC, only 3% of immobilised tyrosinase activity was lost. The operational inactivation rate constant (k(opi)) of the immobilised tyrosinase was 1.25 x 10(-5) min(-1). (C) 2003 Elsevier Ltd. All rights reserved.Öğe Covalent immobilisation of invertase onto a reactive film composed of 2-hydroxyethyl methacrylate and glycidyl methacrylate: properties and application in a continuous flow system(Elsevier Science Sa, 2003) Bayramoglu, G; Akgol, S; Bulut, A; Denizli, A; Arica, MYInvertase was covalently immobilised on the poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) (poly(HEMA-GMA)) film. The invertase immobilisation capacity of the films was increased as the GMA ratio increased in the film structure. The immobilised invertase on the poly(HEMA-GMA-3) composition exhibited an activity of 32.7 U cm(-2) film. The optimum temperature of the immobilised invertase increased by 5 degreesC, and the optimal pH values for the free and the immobilised enzymes were determined as 5.0. The retained activity of the immobilised invertase was between 53 and 85%. Kinetic parameters were determined for immobilised invertase as well as for the free enzyme. The values of the Michael's constant K-m of invertase were significantly larger, ca. 2.7 times upon immobilisation, indicating decreased affinity by the enzyme for its substrate, whereas V-max was smaller for immobilised invertase. Activity of the immobilised invertase was quite stable with respect to free counterpart. After 168 h reaction, only 8% of immobilised invertase activity was lost. The operational inactivation rate constant (k(opi)) of the immobilised invertase at 35 degreesC with 200 mM sucrose was 8.23 x 10(-6) min(-1). (C) 2002 Elsevier Science 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 Poly(2-hydroxyethylmethacrylate)/chitosan dye and different metal-ion-immobilized interpenetrating network membranes: Preparation and application in metal affinity chromatography(John Wiley & Sons Inc, 2003) Bayramoglu, GComposite membranes were synthesized with 2-hydroxyethylmethacrylate and chitosan (pHEMA/chitosan) via an ultraviolet-initiated photopolymerization technique in the presence of an initiator (alpha,alpha'-azobisisobutyronitrile). The interpenetrating network (IPN) membranes were improved by the immobilization of dye molecules via hydroxyl and amino groups on the membrane surfaces from the IPNs. A triazidine dye (Procion Green H-4G) was covalently immobilized as a ligand onto the IPN membranes. The protein showed various affinities to different chelated metal ions on the membrane surfaces that best matched its own distribution of functional sites, resulting in a distribution of binding energies. In support of this interpretation, two different metal ions, Zn(II) and Fe(III), were chelated with the immobilized dye molecules. The adsorption and binding characteristics of the different metal-ion-chelated dye-immobilized IPN membranes for the lysozyme were investigated with aqueous solutions in magnetically stirred cells. The experimental data were analyzed with two adsorption kinetic models, pseudo-first-order and pseudo-second-order, to determine the best fit equation for the adsorption of lysozyme onto IPN membranes. The second-order equation for the lysozyme-dye-metal-chelated IPN membrane systems was the most appropriate equation for predicting the adsorption capacity for all the tested adsorbents. The reversible lysozyme adsorption on the dye-immobilized and metal-ion-chelated membranes obeyed the Temkin isotherm. The lysozyme adsorption capacity of the pHEMA/chitosan dye, pHEMA/chitosan dye-Zn(II), and pHEMA/chitosan dye-Fe(III) membranes were 2.54, 2.85, and 3.64 mg cm(-2), respectively. The nonspecific adsorption of the lysozyme on the plain pHEMA/chitosan membrane was about 0.18 mg cm(-2). (C) 2003 Wiley Periodicals, Inc.Öğe Polyethyleneimine-grafted poly (hydroxyethyl methacrylate-co-glycidyl methacrylate) membranes for reversible glucose oxidase immobilization(Elsevier Science Sa, 2004) Arica, MY; Bayramoglu, GGlucose oxidase (GOD) was immobilized onto polyethyleneimide (PEI) grafted poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) (poly(HEMA-co-GMA)) membranes. The maximum GOD immobilization capacities of the poly(HEMA-co-GMA-4)-PEI membrane were 84 mug/cm(2). The activities of GOD-immobilized onto poly(HEMA-co-GMA-1-5)-PEI membranes were in the range 7.6-14.5 U/cm(2). The storage conditions for the immobilized enzyme preparations were studied and the immobilized enzymes had a long-storage stability (only 7 and 24% activity decrease in 3 months under wet and dry storage conditions, respectively). (C) 2004 Elsevier B.V. All rights reserved.Öğe Polyethylenimine-grafted and HSA-immobilized poly(GMA-MMA) aff inity adsorbents for bilirubin removal(Wiley-Blackwell, 2005) Arıca, M. Yakup; Yalçın, Emine; Bayramoglu, GThe epoxy-group-containing microspheres from cross-linked glycidyl methacrylate and methyl methacrylate, poly(GMA-MMA), were prepared by suspension polymerisation. The epoxy groups of the poly(GMA-MMA) microspheres were used for grafting with an anionic polymer polyethylenimine (PEI) to prepare non-specific affinity adsorbents (poly (GMA-MMA)-PEI) for bilirubin removal. The specificity of the poly(GMA-MMA) -PEI adsorbent to bilirubin was further increased by immobilization of human serum albumin (HSA) via adsorption onto PEI-grafted poly(GMA-MMA) adsorbent. Various amounts of HSA were immobilized on the poly (GMA-MMA) -PEI adsorbent by changing the medium pH and initial HSA concentration. The maximum HSA content was obtained at 68.3 mg g(-1) microspheres. The effects of pH, ionic strength, temperature and initial bilirubin concentration on the adsorption capacity of both adsorbents were investigated in a batch system. Separation of bilirubin from human serum was also investigated in a continuous-flow system. The bilirubin adsorption on the poly(GMA-MMA)-PEI and poly(GMA-MMA)-PEI-HSA was not well described by the Langmuir model, but obeyed the Freundlich isotherm model. The poly(GMA-MMA) -PEI affinity microspheres are stable when subjected to sanitization with sodium hydroxide after repeated adsorption-desorption cycles. (C) 2004 Society of Chemical Industry.Öğe Preparation and application of spacer-arm-attached poly (hydroxyethyl methacrylate-co-glycidyl methacrylate) films for urease immobilisation(Elsevier Science Bv, 2003) Bayramoglu, G; Altinok, H; Bulut, A; Denizli, A; Arica, MYImmobilisation of urease onto plain and six-carbon spacer-arm (i.e. 1,6-diaminohexane) attached poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) [poly (HEMA-GMA)] films was studied. The epoxy groups containing poly(HEMA-GMA-1-3) films were prepared by UV-initiated photopolymerisation of 2-hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA). The spacer arm (i.e. 1,6-diaminohexane) was attached through the epoxy groups of the films. Urease was then covalently immobilised either on the plain or on the spacer-arm-attached poly(HEMA-GMA-2) films using Glutaric dialdehyde as a coupling agent. Incorporation of the spacer-arm resulted in an increase in the apparent activity of the immobilised urease with respect to the enzyme immobilised on the plain films. The urease immobilisation capacity of the films was increased as the GMA ratio increased in the film structure. The activity yield of the immobilised urease on the spacer-arm-attached poly(HEMA-GMA-2) films was 53%, and 36% for the enzyme immobilised on the plain poly(HEMA-GMA-2) films. Both immobilised urease preparations have resistance to temperature inactivation when compared to that of the free form. The temperature profiles were broader for both immobilised preparations than that of the free enzyme. Kinetic parameters were determined for immobilised urease preparations as well as for the free enzyme. The values of the Michaelis constants K(m) for all the immobilised urease preparations were significantly larger, indicating decreased affinity by the enzyme for its substrate, whereas V(max) values were smaller for both immobilised urease preparations. In an 80-h continuous operation with spacer-arm-attached poly(HEMA-GMA-2) films at 35 degreesC, only 7% of immobilised urease activity was lost. The operational inactivation rate constant (k(opi)) of the immobilised urease was 1.51 x 10(-5) min(-1). (C) 2003 Elsevier B.V. All rights reserved.Öğe Surface energy components of a dye-ligand immobilized pHEMA membranes: Effects of their molecular attracting forces for non-covalent interactions with IgG and HSA in aqueous media(Elsevier, 2005) Bayramoglu, G; Arica, MYIn the present paper, we report the study of the adsorption behaviour of human immunoglobulin G (IgG), human serum albumin (HSA) and polyethylenimine (PEI) onto surfaces of Procion Green HE-4BD (PG) immobilized poly(hydroxyethylmethacrylate) (pHEMA) membranes. The adsorption behaviour of the IgG and HSA onto surfaces of the PG-PEI complexed membrane was also studied. Surface wettability and hydrophilicity of all the membranes were investigated by static contact angle measurements. The measurements of the contact angle to various test liquids, i.e., water, glycerol, formamide, diiodomethane (DIM) and ethylene glycol on the investigated membranes were made by sessile drop method. In accordance to the Young equation, the smaller the surface tension of the test liquid, the smaller becomes the contact angles measured on all the investigated membranes surfaces. The highest contact angles were obtained with water, whereas ethylene glycol gave the lowest contact angles for all the tested membranes. Component and parameters of the surface free energy of all the investigated membranes were calculated from measured contact angle values using two methods (the geometric mean by Fowkes and acid-base by van Oss). HSA adsorption was enhanced after complexation of PEI with the immobilized dye-ligand. The adsorption of proteins and PEI significantly changed both the contact angles and component of surface free energies of the investigated membranes. (c) 2005 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.
