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    Comparison of adsorption performances of metal-chelated polyamide hollow fibre membranes in lysozyme separation
    (Elsevier Science Bv, 2002) Şenel, S.; Kassab, A.; Arıca, Y.; Say, R.; Denizli, A.
    Commercially available microporous polyamide hollow fibres are modified by acid hydrolysis to activate the reactive groups and subsequently binding of the ligand, i.e. Cibacron Blue F3GA. Then the Cibacron Blue F3GA-derived hollow fibres were loaded with different metal ions (i.e. Zn(II), Cu(II), Ni(II)) to form the metal chelate. The internal polymer matrix was characterised by scanning electron microscopy. The effects of pH, initial concentration of lysozyme, metal type and temperature on the adsorption of lysozyme to the metal-chelated hollow fibres were examined in a batch reactor. The non-specific adsorption of lysozyme onto the polyamide hollow fibres was 1.8 mg/g. Cibacron Blue F3GA immobilisation increased the lysozyme adsorption up to 62.3 mg/g. Metal-chelated hollow fibres showed a significant increase of the adsorption efficiency. Lysozyme adsorption capacities of Zn(II), Cu(II) and Ni(Il)-chelated hollow fibres were different. The maximum capacities of Zn(II), Cu(II) or Ni(Il)-chelated hollow fibres were 144.2, 75.2 and 68.6 mg/g, respectively. Significant amount of the adsorbed lysozyme (up to 97%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pH 8.0 and 25 mM EDTA at pH 4.9. Repeated adsorption-desorption process showed that this novel metal-chelated polyamide hollow fibres are suitable for lysozyme adsorption. (C) 2002 Published by Elsevier Science B.V.
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    Dye-affinity hollow-fibres and their lysozyme adsorption-desorption characteristics
    (John Wiley & Sons Ltd, 2001) Şenel, S.; Akgöl, S.; Arica, Y.; Denizli, A.
    Dye-affinity adsorption is increasingly used for protein separation. Hollow-fibres have advantages as adsorbents in comparison to conventional bead supports because they are not compressible and can eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of polyamide hollow-fibres to which Reactive Green HE-4BD was attached for adsorption of lysozyme. The hollow-fibre was characterized by scanning electron microscopy. These dye-carrying hollow-fibres (26.3 mu mol g(-1)) were used in the lysozyme adsorption-elution studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye-attached hollow-fibres was studied in a batch system. The non-specific adsorption of lysozyme on the polyamide hollow-fibres was 1.8 mgg(-1). Reactive Green HE-4BD attachment significantly increased the lysozyme adsorption up to 41.1 mgg(-1). Langmuir adsorption model was found to be applicable in interpreting lead adsorption by Reactive Green HE-4BD attached hollow fibres. Significant amount of the adsorbed lysozyme (up to 95%) was eluted in lh in the elution medium containing 1.0M NaSCN at pH 8.0. In order to determine the effects of adsorption conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We concluded that polyamide dye-affinity hollow-fibres can be applied for lysozyme adsorption without causing any significant conformational changes. Repeated adsorption-elution processes showed that these dye-attached hollow-fibres are suitable for lysozyme adsorption. (C) 2001 Society of Chemical Industry.
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    Zinc ion-promoted adsorption of lysozyme to Cibacron Blue F3GA-attached microporous polyamide hollow-fiber membranes
    (Elsevier Science Bv, 2001) Şenel, S.; Say, R.; Arıca, Y.; Denizli, A.
    Dye-affinity and metal chelate affinity adsorption are increasingly used for protein separation. Synthetic hollow fiber membranes have advantages as support matrices in comparison to conventional bead supports because they are not compressible and they eliminate internal diffusion limitations. The goal of this study was to explore in detail the performance of hollow fibers composed of modified polyamide to which Cibacron Blue F3GA and Zn(II) were attached for adsorption of lysozyme. The polymer matrix was characterized by scanning electron microscopy. These dye-affinity and Zn(II) chelated hollow-fibers were used in the lysozyme adsorption-elution studies. The effects of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye-attached and metal-chelated hollow-fibers were studied in a batch reactor. The effect of Zn(II) loading on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the polyamide hollow-fibers was 1.8 mg g(-1). Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 63.2 mg g(-1). Lysozyme adsorption capacity of the Zn(II) chelated hollow-fibers (144.2 mg g(-1)) was greater than that of the Cibacron Blue F3GA-attached hollow-fibers. A significant amount of the adsorbed lysozyme (up to 97%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pn 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- and metal-chelate affinity chromatography with polyamide hollow-fibers can be applied for lysozyme adsorption without causing any significant conformational changes and denaturation. Repeated adsorption/elution processes showed that these novel dye-attached and Zn(II) chelated hollow-fibers are suitable for lysozyme adsorption. (C) 2001 Elsevier Science B.V. All rights reserved.