Preparation of Zn2+-chelated poly(HEMA-MAH) cryogel for affinity purification of chicken egg lysozyme

Supermacroporous poly(2-hydroxyethyl methacrylate) [poly(HEMA)]-based monolithic cryogel column was prepared by radical cryocopolymerization of HEMA with N-methacryloyl-L-histidine methyl ester (MAH) as functional comonomer and N,N'-methylene-bisacrylamide (MBAAm) as crosslinker directly in a plastic syringe for affinity purification of lysozyme from chicken egg white. The monolithic cryogel containing a continuous polymeric matrix having interconnected pores of 10-50 mu m size was loaded with Zn2+ ions to form the metal chelate with poly(HEMA-MAH) cryogel. Poly(HEMA-MAH) cryogel was characterized by swelling studies, FTIR, scanning electron microscopy, and elemental analysis. The equilibrium swelling degree of the poly(HEMA-MAH) monolithic cryogel was 5.62 g H2O/g cryogel. Poly(HEMA-MAH) cryogel containing 45.8 mu mol MAH/g was used in the adsorption/desorption of lysozyme from aqueous solutions. The nonspecific adsorption of lysozyme was very low (7.5 mg/g). The maximum amount of lysozyme adsorption from aqueous solution in phosphate buffer was 209 mg/g at pH 7.0. It was observed that lysozyme could be repeatedly adsorbed and desorbed with the poly (HEMA-MAH) cyogel without significant loss of adsorption capacity. (C) 2008 Wiley Periodicals, Inc.