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    Nonporous monosize polymeric sorbents: Dye and metal chelate affinity separation of lysozyme
    (John Wiley & Sons Inc, 2000) Denizli, A; Yavuz, H; Garipcan, B; Arica, MY
    Lysozyme adsorption onto dye-attached nonporous monosize poly(2-hydroxyethyl-methacrylate-methylmethacrylate) [poly(HEMA-MMA)] microspheres was investigated. Poly(HEMA-MNA) microspheres were prepared by dispersion polymerization. The monochloro-triazine dye, Cibacron Blue F3GA, was immobilized covalently as dye-ligand. These dye-affinity microspheres were used in the lysozyme adsorption-desorption studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye-attached and metal-chelated microspheres were studied in a batch reactor. Effect of Cu(II) chelation on lysozyme adsorption was also studied. The nonspecific adsorption of lysozyme on the poly(HEMA-MMA) microspheres was 3.6 mg/g. Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 247.8 mg/g. Lysozyme adsorption capacity of the Cu(II) incorporated microspheres (318.9 mg/g) was greater than that of the Cibacron Blue F3GA-attached microspheres. Significant amount of the adsorbed lysozyme (up to 97%) was desorbed in 1 h in the desorption medium containing 1.0M NaSCN at pH 8.0 and 25 mM EDTA at pH 4.9. In order to examine the effects of separation conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We conclude that dye-attached and metal-chelate affinity chromatography with poly(HEMA-MMA) microspheres can be applied for lysozyme separation without causing any significant changes and denaturation. Repeated adsorption/desorption processes showed that these novel dye-attached monosize microspheres are suitable for lysozyme adsorption. (C) 2000 John Wiley & Sons, Inc.
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    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, A
    Various 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.