MODIFIED PMMA MONOSIZE MICROBEADS FOR GLUCOSE-OXIDASE IMMOBILIZATION

Glucose oxidase (GOD) was immobilized onto modified polymethylmethacry late (PMMA) microspheres by covalent bonding. Monosize PMMA microbeads with 1.5 mu m diameter were produced by dispersion polymerization of methylmethacrylate by using polyvinyl alcohol as a stabilizer. Hydroxy l groups on the microbeads were first converted to aldehyde groups by periodate oxidation. Three amino compounds, namely ammonium hydroxide, ethylene diamine and hexamethylene diamine were incorporated through the aldehyde groups. Then, GOD molecules were immobilized through the spacer-arms by using glutaraldehyde. The highest amount of immobilizat ion and activity were obtained in which hexamethylene diamine was used as the spacer-arm with 14 atom length, and were 2.1 mg g(-1) polymer and 129 IU g(-1) polymer, respectively. The optimal conditions for GOD immobilization were obtained as follows: pH, 6.0; temperature, 30 deg rees C; immobilization time, 60 min; and GOD initial concentration, 0. 10 mg ml(-1). The optimal conditions for the GOD-immobilized PMMA micr obeads were at pH 6.0 and at a temperature of 30 degrees C. The K-m an d V-max values of the GOD-immobilized PMMA microbeads were, 13.79 mM a nd 26.31 mM min(-1) calculated by non-linear regression, respectively.