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    Cibacron Blue F3GA and Cu(II) derived poly(2-hydroxyethylmethacrylate) membranes for lysozyme adsorption
    (Elsevier Science Bv, 1998) Denizli, A; Senel, S; Arica, MY
    Lysozyme adsorption onto Cibacron Blue F3GA and Cu(II) derived poly(2-hydroxyethyl methacrylate) [poly(HEMA)] membranes was investigated. Microporous poly(HEMA) membranes were prepared by photopolymerization of HEMA. The triazine dye, Cibacron Blue F3GA was attached covalently as a dye-ligand. These dye-membranes with a swelling ratio of 58% (w/w), and carrying different amounts of Cibacron Blue F3GA (between 0.35 and 1.07 mu mol cm(-2)) were used in the lysozyme adsorption studies. The effect of initial concentration and pH on the adsorption efficiency of dye-derived and metal-chelated membranes were studied in a batch reactor. The effect of Cu(II) incorporation on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the poly(HEMA) membranes was 0.9 mu g cm(-2). Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 133.3 mu gcm(-2) Lysozyme adsorption capacity of the Cu(II) incorporated membranes (165.1 mu g cm(-2)) was greater than that of the Cibacron Blue F3GA-attached membranes. More than 85% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 0.5 M potassium thiocyanate (KSCN) at pH 8.0. (C) 1998 Elsevier Science B.V. All rights reserved.
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    Invertase immobilized on spacer-arm attached poly(hydroxyethyl methacrylate) membrane: Preparation and properties
    (John Wiley & Sons Inc, 2000) Arica, MY; Senel, S; Alaeddinoglu, NG; Patir, S; Denizli, A
    Microporous poly(2-hydroxyethyl methacrylate) (pHEMA) membrane was prepared by UV-initiated photopolymerization. The spacer arm (i.e., hexamethylene diamine) was attached covalently and then invertase was immobilized by the condensation reaction of the amino groups of the spacer arm with carboxyl groups of the enzyme in the presence of carbodiimides. The values of the Michael's constant K-m of invertase were significantly larger (ca. 2.5 times) upon immobilization, indicating decreased affinity by the enzyme for its substrate, whereas V-max was smaller for the immobilized invertase. Immobilization improved the pH stability of the enzyme as well as its temperature stability. Thermal stability was found to increase with immobilization and at 70 degrees C the half times for the activity decay were 12 min for the free enzyme and 41 min for the immobilized enzyme. The immobilized enzyme activity was found to be quite stable in repeated experiments. (C) 2000 John Wiley & Sons, Inc.
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    New metal chelate sorbent for albumin adsorption: Cibacron blue F3GA-Zn(II) attached microporous poly(HEMA) membranes
    (John Wiley & Sons Inc, 1998) Denizli, A; Salih, B; Senel, S; Arica, MY
    Poly(2-hydroxyethyl methacrylate) [poly(HEMA)] membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (alpha-alpha'-azobis-isobutyronitrile, AIBN). The triazine dye Cibacron Blue F3GA was attached as an affinity ligand to poly(HEMA) membranes, covalently. These affinity membranes with a swelling ratio of 58% and containing 10.7 mmol Cibacron Blue F3GA/m(2) were used in the albumin adsorption studies. After dye-attachment, Zn(TI) ions were chelated within the membranes via attached-dye molecules. Different amounts of Zn(II) ions [650-1440 mg Zn(II)/m(2)] were loaded on the membranes by changing the initial concentration of Zn(II) ions and pH. Bovine serum albumin (BSA) adsorption on these membranes from aqueous solutions containing different amounts of BSA at different pH was investigated in batch reactors. The nonspecific adsorption of BSA on the poly(HEMA) membranes was negligible. Cibacron Blue F3GA attachment significantly increased the BSA adsorption up to 92.1 mg BSA/m(2). Adsorption capacity was further increased when Zn(II) ions were attached (up to 114.8 mg BSA m(2)). More than 90% of the adsorbed BSA was desorbed in 1 h in the desorption medium containing 0.5M NaSCN at pH 8.0 and 0.025M EDTA at pH 4.9. (C) 1998 John Wiley & Sons, Inc.