Performance of Different Metal–Dye Chelated Affinity Adsorbents of Poly(2-Hydroxyethyl Methacrylate) in Lysozyme Separation

Abstract

The triazine dye Cibacron Blue F3GA was covalently immobilized as an affinity ligand onto microporous poly(2-hydroxyethyl methacrylate) (pHEMA) membranes. Three different metal ions [i. e., Fe(III), Zn(II), or Cu(II)] were then chelated with the immobilized Cibacron Blue F3GA molecules. Lysozyme adsorption onto these affinity adsorbents from aqueous solutions containing different amounts of lysozyme at different pH was investigated in a batch system. Lysozyme adsorption capacity of all of the metal-dye-immobilized membranes was greater than that of the dye-immobilized membranes. The nonspecific adsorption of the protein on the pHEMA membranes was negligible. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The maximum capacity (qm ) of the Fe(III)–Zn(II),–or Cu(II)–dye chelated membranes for lysozyme adsorption (384, 326, and 306 μg/cm2) was greater than that of the dye-immobilized membrane (224 μg lysozyme/cm2), respectively. The dissociation constant (kd ) values were found to be 2.51 × 10−7 M with dye-immobilized membrane, and 2.32 ×10−7×10−7and 2.40 ×10−7 M with the Fe(III)–Zn(II),–and Cu(II)–dye-chelated membranes, respectively. More than 95% of the adsorbed lysozyme was desorbed in 60 min in the desorption medium containing 0.5 M KSCN at pH 8.0.