ENZYME ELECTRODES WITH GLUCOSE-OXIDASE IMMOBILIZED ON STOBER GLASS-BEADS

In this study we report the development and experimental evaluation of a miniature Stober glass-coated enzyme electrode for glucose biosenso r applications. The enzyme - glucose oxidase - is chemically immobiliz ed onto the surface of the Stober glass beads after a silanization pro cedure. The sensors were fabricated using grass beads of different rad ii ranging from 20 nm to 100 nm. The overall thickness of the glass co ating was about 1.4 mu m in all cases. Initial calibration curves of t he electrodes show an increase in the response value with decrease in the bead radius. Life-time evaluation tests, however, demonstrate a di fferent behavior of the electrodes. At the end of a 50 day test, the e lectrode with bead radius of 70 nm remained most stable. The response of this electrode was stable over this period of time and no apparent decrease in its sensitivity was observed. This study suggests that the re may be a relation between the immobilized enzyme stability and the porosity of the glass-bead layer. Preliminary tests in undiluted blood plasma suggest that electrodes can be used for glucose measurements i n body fluids.