A novel matrix for hydrophobic interaction chromatography and its application in lysozyme adsorption

A novel 1-naphthylamine (NA) coupled poly(2-hydroxyethyl methacrylate-co-N-methacryloyl-(L)-histidine methyl ester) [NA-PHEMAH] supermacroporous monolithic hydrophobic cryogel was prepared via covalent coupling of NA to PHEMAH for adsorption of lysozyme from aqueous solution. Firstly, PHEMAH monolithic cryogel was prepared by radical cryocopolymerization of HEMA with MAH as a functional comonomer and N,N'-methylene-bisacrylamide (MBAAm) as a crosslinker directly in a plastic syringe, and then NA molecules were covalently attached to the imidazole rings of MAH groups of the polymeric structure. The prepared, NA-PHEMAH, supermacroporous monolithic hydrophobic cryogel was characterized by scanning electron microscopy (SEM). The effects of initial lysozyme concentration, pH, salt type, temperature and flow rate on the adsorption efficiency of monolithic hydrophobic cryogel were studied in a column system. The maximum amount of lysozyme adsorption from aqueous solution in phosphate buffer was 86.1 mg/g polymer at pH 8.0 with a flow rate of 1 mL/min. It was observed that lysozyme could be repeatedly adsorbed and desorbed with the NA-PHEMAH monolithic hydrophobic cryogel without significant loss of the adsorption capacity.