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Öğe Dithiocarbamate-incorporated monosize polystyrene microspheres for selective removal of mercury ions(Elsevier Science Bv, 2000) Denizli, A; Kesenci, K; Arica, Y; Piskin, EDithiocarbamate-incorporated monosize polystyrene based microspheres (2 mu m in diameter) were used for selective removal of Hg(II) from aqueous solutions containing different amounts of Hg(II) (10-100 ppm). Adsorption rates were observed as high at the beginning of adsorption and then equilibrium was reached in about 30 min. The maximum Hg(II) adsorption capacity of the dithiocarbamate-incorporated PS microspheres was about 33.2 mg per gram of dry polymer, which was observed at pH 7.0. While non-specific Hg(II) adsorption onto the plain microspheres was 0.85 mg per gram of dry microsphere. The Hg(II) adsorption ability increased with increasing pH, in the range where the solubility of the Hg(II) was not affected by the pH. The preferential (i.e., competitive adsorption) binding of Hg(II) by the microspheres implies that this sorbent system might contain higher-affinity binding sites for Hg(ll) than Cu(II), Cd(II) and Pb(II) ions. More than 96% of the adsorbed Hg(II) was desorbed in 15 min by using 0.1 M HNO3 as an elution agent. The regeneration of the dithiocarbamate-incorporated PS microspheres was also sufficient. (C) 2000 Elsevier Science B.V. All rights reserved.Öğe Monosize and non-porous p(HEMA-co-MMA) microparticles designed as dye- and metal-chelate affinity sorbents(Elsevier Science Bv, 2000) Denizli, A; Yavuz, H; Arica, YCongo red was immobilised onto monosize and non-porous poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) [p(HEMA-co-MMA)] copolymer microparticles (4.0 mu m in diameter). Then Fe(III) ions were complexed by chelation with the immobilised congo red molecules. Different amounts of Fe(III) ions were loaded on the dye-derived microparticles by changing the concentration of Fe(III) ions and pH of the reaction medium. Congo red-derived and Fe(III)-complexed microparticles were used in the adsorption of glucose oxidase, catalase, lysozyme and bovine serum albumin. The maximum adsorption capacities of these microparticles were determined by changing pH and the concentration of the proteins in the adsorption medium. Their adsorption behavior can be described at least approximately with the Langmuir equation. Glucose oxidase, catalase, lysozyme and bovine serum albumin adsorption capacities of the Fe(III) complexed microparticles (165.1, 135.2, 67.6 and 44.5 mg g(-1)) were higher than those of the congo red-immobilised microparticles (125.9, 94.2, 35.8 and 21.2 mg g(-1), respectively). The non-specific adsorption of the proteins on the p(HEMA-co-MMA) microparticles was negligible. The resulting dye- and metal-chelate affinity microparticles have excellent reusability and long term storage stability. (C) 2000 Elsevier Science B.V. All rights reserved.Öğe Poly(styrene-hydroxyethyl methacrylate) monodisperse microspheres as specific sorbent in dye affinity adsorption of albumin(Taylor & Francis Inc, 2004) Uzun, L; Odabasi, M; Arica, Y; Denizli, AIn this study, human serum albumin (HSA) adsorption properties of reactive green HE-4BD-attached monodisperse poly(styrene-2-hydroxyethyl methacrylate) [poly(St-HEMA)] microspheres were investigated. Poly(St-HEMA) microspheres with an uniform size of 4.0 mum in diameter were produced by the dispersion copolymerization of St and HEMA in an ethanol-water medium. Reactive green HE-4BD was covalently attached onto the poly(St-HEMA) microspheres via a nucleophilic substitution reaction between the hydroxyl groups of HEMA and triazinyl chloro groups of dye with the equilibrium coupling capacity of 45.8 mumol dye (g polymer)(-1). The poly(St-HEMA) monodisperse microspheres were characterized by scanning electron microscopy. The effect of concentration of HSA, medium pH, and ionic strength on the adsorption efficiency of dye-attached microspheres were studied in a batch system. The nonspecific adsorption of HSA on the poly(St-HEMA) microspheres was 2.2 mg g(-1). Reactive green HE-4BD attachment significantly increased the HSA adsorption up to 221 mg g(-1). The langmuir adsorption model was found to be applicable in interpreting HSA adsorption by reactive green HE-4BD attached microspheres. Significant amount Of the adsorbed HSA (up to 92%) was eluted in 1 hr in the elution medium containing 1.0-M NaCl. To determine the effects of adsorption conditions on possible conformational changes of HSA structure, fluorescence spectrophotometry was employed. We resulted that poly(St-HEMA) dye-affinity microspheres can be applied for HSA adsorption without causing any significant conformational changes. Repeated adsorption/ elution processes showed that these dye-attached monodisperse microspheres are suitable for HSA adsorption.Öğe Protein A-immobilized microporous polyhydroxyethylmethacrylate affinity membranes for selective sorption of human-immunoglobulin-G from human plasma(Vsp Bv, 2000) Denizli, A; Arica, YMicroporous membranes made of poly(2-hydroxyethylmethacrylate) [poly(HEMA)] carrying protein A were used for selective sorption of human-IgG from human plasma. Poly(HEMA) membranes were prepared by a photo-polymerization technique, and activated by cyanogen bromide (CNBr) in an alkaline medium (pH 11.5). Bioligand protein A was then immobilized by covalent binding onto these CNBr-activated membranes. The amount of immobilized protein A was controlled by changing pH and the initial concentrations of CNBr and protein A. The non-specific adsorption of protein A on the plain poly(HEMA) membranes was 2.9 mu g cm(-2). Maximum protein A immobilization was observed at pH 9.5. Up to 180 mu g cm(-2) was immobilized on the CNBr-activated poly(HEMA) membranes. The maximum adsorption of human-IgG on the protein A-immobilized poly(HEMA) membranes was observed at pH 8.0. The non-specific adsorption of human-IgG onto the plain poly(HEMA) membranes was low (about 4.4 mu g cm(-2)). Higher human-IgG adsorption values (up to 394 mu g cm(-2)) were obtained in which the protein A-immobilized poly(HEMA) membranes were used. Much higher amounts of human-Igg (up to 489 mu g cm(-2)) were adsorbed from human plasma. Up to 91 % of the adsorbed human-IgG was desorbed by using 0.1 M aminoacetic acid as elution agent. The adsorption-desorption cycle was repeated ten times using the same polymeric membranes. There was no remarkable reduction in the adsorption capacity of the protein A-immobilized poly(HEMA) membranes.Öğe Removal of cadmium(II) ions from human plasma by thionein modified pHEMA based membranes(Elsevier Science Bv, 2000) Denizli, F; Arica, Y; Denizli, AMicroporous poly(2-hydroxyethylmethacrylate) [pHEMA] membranes carrying Cibacron Blue F3GA and/or thionein were prepared and used for cadmium(II) removal from human plasma. pHEMA membranes were produced by a photopolymerization of HEMA in the presence of azobisisobutyronitrile. The reactive dye-ligand Cibacron Blue F3GA was then covalently attached onto the pHEMA membranes. The maximum dye-loading was 1.07 mu mol/cm(2). Then, thionein was adsorbed onto the Cibacron Blue F3GA-carrying membranes. The maximum amount of thionein adsorbed was 0.92 mu mol/cm(2). The aqueous swelling properties and contact angle lair underwater) of the pHEMA membrane were not observed to change following derivatisation with Cibacron Blue F3GA. These hydrophilic membranes (contact angle value: 45.3 degrees) with a swelling ratio of 58% (w/w), and carrying Cibacron Blue F3GA and/or thionein were used in the Cd(II) removal studies. The maximum amounts of Cd(II) removed from human plasma by Cibacron Blue F3GA-attached and Cibacron Blue F3GA-attached/thionein adsorbed pHEMA membranes were of 1.72 mu mol used as pectively. Cd(II) ions could be repeatedly adsorbed and desorbed with both types of these novel metallo-peptide affinity pHEMA membranes without noticeable loss in their Cd(II) adsorption capacity. (C) 2000 Elsevier Science B.V. All rights reserved.Öğe Removal of heavy metal ions from aquatic solutions by membrane chromatography(Elsevier Science Bv, 2000) Denizli, A; Say, R; Arica, YPolyvinylalcohol membranes were prepared by a solvent casting technique. Metal-complexation ligand, i.e. monochlorotriazinyl-dye Cibacron Blue F3GA was then attached. These membranes with a high water content of 119%, and containing 8.7 mmol Cibacron Blue F3GA/m(2) were used in the adsorption/stripping of some selected heavy metal ions [Cu(II), Hg(II), Pb(II) and Cd(II)] from aquatic solutions containing varying initial concentration of metal ions. Adsorption rates were very high, and equilibrium was achieved in about 10 min. The non-specific adsorption of heavy metal ions on the plain membranes was low [0.63 mmol/m(2) for Cu(II), 0.75 mmol/m(2) for Hg(II), 0.94 mmol/m(2) for Pb(II) and 1.22 mmol/m(2) for Cd(II)]. The maximum adsorptions of heavy metal ions onto the Cibacron Blue F3GA-attached affinity membranes for non-competitive conditions were 16.9 mmol/m(2) for Hg(II), 19.2 mmol/m(2) for Cu(II), 25.8 mmol/m(2) for Pb(II), 32.4 mmol/m(2) for Cd(II). The observed order in adsorption was found to be Cd(II) > Pb(II) > Cu(II) > Hg(II). Different behavior was observed for competitive adsorption. The order of affinity was Cu(II) > Cd(II) > Hg(II) > Pb(II). Regeneration of polyvinylalcohol membranes was done by using 0.1 M HNO3 in 30 min. Heavy metal ions could be repeatedly adsorbed and stripped without significant decrease in adsorption capacity. The experimental data of adsorption from solutions containing metal ions were found to correlate well with Langmuir isotherm equation. (C) 2000 Elsevier Science B.V. All rights reserved.Öğe Synthesis and adsorption properties of poly(2-hydroxyethylmethacrylate-co-methacrylamidophenylalanine) membranes for copper ions(Elsevier Science Bv, 2000) Denizli, A; Say, R; Patir, S; Arica, YIn the first step of this study, the metal complexing ligand, 2-methacrylamidophenylalanine (MAPA), was synthesized by using methacrylochloride and phenylalanine. The MAPA monomer was characterized by NMR. Then, poly(2-hydroxyethylmethacrylate -co-2-methacrylamidophenylalanine) [p(HEMA-co-MAPA)] membranes were prepared by UV-initiated photo-polymerization of HEMA and MAPA in the presence of an initiator (azobisisobutyronitrile? AIBN). p(HEMA-co-MAPA) membranes were characterized by FTIR and elemental analysis. These p(HEMA-co-MAPA) affinity membranes with a swelling ratio of 133.2%, and containing 18.9 mmol MAPA/m(2), were used in the adsorprion-desorption of copper(II) ions from synthetic solutions. Adsorption equilibria was reached in about 2 h. The maximum adsorption of Cu(II) ions onto pHEMA was about 0.54 mmol Cu(II)/m(2). The MAPA incorporation significantly increased the Cu(II) adsorption capacity by chelate formation of Cu(II) ions with MAPA molecules (23.8 mmol Cu(II)/m(2)), which was observed at pH 7.0. The chelating membrane can be easily regenerated by 0.1 M HNO3 with higher effectiveness. (C) 2000 Elsevier Science B.V. All rights reserved.Öğe Synthesis and mechanical properties of interpenetrating networks of polyhydroxybutyrate-co-hydroxyvalerate and polyhydroxyethyl methacrylate(Elsevier Sci Ltd, 1998) Gursel, I; Balcik, C; Arica, Y; Akkus, O; Akkas, N; Hasirci, VNaturally occurring, biocompatible, and biodegradable polyhydroxybutyrate-co-hydroxyvalerate (PHBV), and synthetic, non-degrading polyhydroxyethylmethacrylate (PHEMA) membranes were prepared and their mechanical properties were studied. Their performances were compared with the interpenetrating networks (IPN) prepared by photopolymerization of HEMA in the presence of PHBV. The modulus of elasticity, failure stress and failure strain indicated that the IPNs are viscoelastic with properties closer to PHEMA but much stronger than PHEMA homopolymers. Incorporation of PHBV (7, 14 and 22% I-IV) affected the mechanical properties positively. Increasing the PHBV content increased the modulus of elasticity and failure stress nearly in all samples tested. PHBV (7, 14, and 22% HV, 300 mg) samples showed an approximately 17-30 fold increase in terms of modulus of elasticity and 7-10 fold increase in terms of failure stress. The scanning electron micrographs of the membranes showed that the PHEMA membranes are more porous than the PHBV membranes but the IPN structure displayed channels on the membrane surface indicating that HEMA polymerization was achieved by using the PHBV as a scaffold. With the use of the present technique, it is possible to synthesize supramolecular structures from molecules that are not compatible and miscible with each other. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.Öğe Synthesis of Poly[(hydroxyethyl methacrylate)-co-(methacrylamidoalanine)] Membranes and Their Utilization as an Affinity Sorbent for Lysozyme Adsorption(Wiley-V C H Verlag Gmbh, 2001) Garipcan, B; Bereli, N; Patir, S; Arica, Y; Denizli, AVarious adsorbent materials have been reported in the literature for protein separation. We have developed a novel and new approach to obtain high protein-adsorption capacity utilizing a 2-methacrylamidoalamne-containing membrane. An amino acid ligand 2-methacrylamidoalanine (MAAL) was synthesized from methacrylochloride and alanine. Then, poly[(2-hydro-xyethel methacrylate)-co-(2-methacrylamidoalanine)] [p(HEMA-co-MAAL)] membranes were prepared by UV-initiated photopolymerization of HEMA and MAAL. The synthesized MAAL monomer was characterized by NMR spectrometry. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, scanning electron microscopy,FT-IR spectroscopy and elemental analysis. These membranes have large pores; the micropore dimensions are around 5-10 mum. p(HEMA-co-MAAL) affinity membranes with a swelling ration of 198.9%, and containing 23.9 (mmol MAAL).m(-2) were used in the adsorption of lysozyme (0.1-3.0 mg.ml(-1)) and at different pH values (4.0-8.0). The effect of Cu(II) incorporation on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the pHEMA membranes was 0.9 mug-cm(-2). Incorporation of MAAL molecules into the polymeric structure significantly increased the lysozyme adsorption up to 2.96 mg.cm(-2). The lysozyme-adsorption capacity of the membranes incorporated with Cu(III) (9.98 mg.cm(-2)) was greater than that of the p(HEMA-co-MAAL) membranes. More than 85% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl. The p(HEMA-co-MAAL) membranes are suitable for repeated use for more than 5 cycles without noticable loss of capacity. These features make p(HEMA-co-MAAL) membrane a very good candidate for bioaffinity adsorption. Adsorption rates of lysozyme: MAAL loading: 23.9 mmol.m(-2); pH: 7.0; temperature: 20 degreesC; total external membrane surface area in each batch: 100 cm(2).l(-1); Each point is the average of five parallel studies.Öğe Therapeutic affinity adsorption of iron(III) with dye- and ferritin-immobilized pHEMA adsorbent(John Wiley & Sons Inc, 2001) Yavuz, H; Arica, Y; Denizli, AMicroporous poly(2-hydroxyethylmethacrylate) (pHEMA) films carrying cibacron blue F3GA, Congo red, and ferritin were prepared and used for iron(III) removal from human plasma. pHEMA films were produced by a photopolymerization of 2-hydroxyethylmethacrylate in the presence of azobisisobutyronitrile. The reactive dye ligands cibacron blue F3GA, Congo red, and bioligand ferritin were then covalently attached to the pHEMA films. The maximum dye loadings were 1.07 and 0.80 mu mol/cm(2) for cibacron blue and Congo red, respectively. The maximum amount of ferritin attached was 1.04 x 10(-3) mu mol/cm(2). Characterizations of the films were achieved by contact-angle, water-uptake, and scanning electron microscopy studies as well as atomic force microscopy images. The aqueous water-uptake properties and contact angles lair underwater of the pHEMA films did not change after derivatization with cibacron blue F3GA, Congo red, and ferritin. These hydrophilic films (contact angle = 45.3 degrees), having a swelling ratio of 58% (w/w) and carrying cibacron blue F3GA, Congo red, and ferritin, were used in Fe(III) removal studies. The maximum amounts of Fe(III) removed from human plasma by cibacron blue F3GA-, Congo red-, and ferritin-attached pHEMA films were 3.80 mug/cm(2) for cibacron blue F3GA, 4.41 mug/cm(2) for Congo red, and 8.1 mug/cm(2) for ferritin-attached films. Fe(III) ions could be repeatedly adsorbed and desorbed with these affinity pHEMA films without a noticeable loss in their Fe(III) adsorption capacity. (C) 2001 John Wiley & Sons, Inc.
