Glucose Sensor Carrying Monomolecular Layer of Glucose Oxidase Covalently Bound to Tin(IV) Oxide Electrode

Glucose oxidase was covalently immobilized, as a monomolecular layer, onto a tin(IV) oxide (SnO2) electrode via (1) 2, 4, 6-trichoro-1, 3, 5-triazine or (2) 3-aminopropyltriethoxysilane and glutaraldehyde, to give an amperometric glucose sensor. The sensor thus obtained exhibited an order-of-magnitude higher specific sensitivity (i.e. sensitivity per immobilized enzyme molecule) and, even without continuous oxygen supply, a higher upper detection limit than a conventional type sensor carrying a crosslinked glucose oxidase membrane. The sensors showed a long-term stability (>1 month). When this sensor was applied to a flow injection glucose analyzer system, it showed a wide dynamic range (10-5-10-1M) and high analysis frequency (15 samples h-1 at a flow rate of 0.5ml min-1). The sensor was also used as a detector in a high performance liquid chromatograph system. The amount of glucose in a control serum was determined, in good agreement with the value determined by conventional methods.