Poly(EGDMA/AAm) copolymer beads: a novel carrier for enzyme immobilization

Abstract

In this study, we evaluated a new carrier (i.e., the poly(EGDMA/AAm copolymer beads) for enzyme immobilization. Two different types of copolymer beads with different swellabilities with an average diameter of about 200 μm were produced by suspension copolymerization of the respective comonomers, with or without using toluene. BPO and PVA were used as the initiator and the stabilizer. The copolymer beads produced without toluene were nonporous and nonswellable. While porous and swellable (swelling ratio: 14.28%) beads were obtained in which toluene was used as the diluent. Both type of beads were modified by using glutaraldehyde and hexamethylene diamine as the coupling agent and the spacer-arm, respectively. Immobilization of a model enzyme (i.e., glucose oxidase) was studied to show the feasibility of using these beads as an enzyme carrier. More enzyme, but with very low activities, were immobilized on the beads with relatively lower swellabilities. While much higher activities were observed on the beads with relatively higher swellabilities prepared with toluene. Incorporation of the spacer-arm (i.e., hexamethylene diamine) increased the apparent activity of the immobilized enzyme. The optimal glutaraldehyde concentrations to achieve the highest immobilized enzyme activities for the swellable and nonswellable beads were 23.1 and 4.8% (v/v), respectively, while the optimal hexamethylene diamine concentrations to achieve the highest immobilized enzyme activities for these beads were 0.10 and 0.16 mmol/ml, respectively.