Preparation of clay–poly(glycidyl methacrylate) composite support for immobilization of cellulase

• SI-ATRP of p(GMA) yields fibrous brushes on clay-polymer composite particles.
• Amino modification of the polymer brushes gives high enzyme binding capacity.
• Immobilization of cellulase on support is simple and applicable to other enzymes.
• Immobilized enzyme preparations have high thermal and storage stabilities.
• Immobilized cellulase preparations can be adapted for industrial application.

A composite material was synthesized by grafting of glycidyl methacrylate onto clay using surface initiation atom transfer radical polymerization (SI-ATRP) technique. Epoxy group of the grafted p(GMA) chains was reacted with hexamethylenediamine (HMDA). The composite material was characterized using scanning electron microscopy (SEM) and FTIR. Cellulase from Trichoderma reesei was immobilized on the aminated composite particles via adsorption and covalent binding methods. The amounts of adsorbed enzyme on the aminated composite particles were 43.4 mg/g. The recovered activities of the adsorbed and covalently immobilized cellulase were found to be 87.7% and 73.2% for the substrate, carboxymethyl cellulose (CMC, 1.0 g/L). The pH stabilities and thermo-stabilities, repeated use and storage stabilities of both immobilized cellulase preparations were evaluated. The immobilized cellulase preparations have better stabilities and higher retained activities with respect to pH, temperature and storage than those of the free enzyme. Operational stability of the covalently immobilized cellulase was tested in a continuous flow system, and the activity loss was about 4% at the end of 48 h operation period.