A NEW METHOD FOR THE CONTROLLED IMMOBILIZATION OF ENZYME IN INORGANICGELS (LAPONITE) FOR AMPEROMETRIC GLUCOSE BIOSENSING

The feasibility of an amperometric glucose biosensor based on immobili zation of glucose oxidase (GOD) in inorganic gels (laponite) is invest igated. The gels modified with enzyme were deposited onto platinum ele ctrodes and then were exposed to glutaraldehyde vapor. The effects of different parameters (glutaraldehyde crosslinking and time of drying) on the performances of the biosensor have been studied. For optimum co nditions, remarkably good characteristics were obtained: larger dynami c range (0.1-4 mM of glucose), higher i(max) higher sensitivity (three fold better than this obtained through immobilization of enzymes in la ponite films). The main advantage of the biosensor reported here is it s long stability. The biosensor was kept for several weeks in a buffer solution at 4 degrees C. About 450 measurements were done without any loss of the linearity in the range (0.1-4 mM). The possibility of an increase in the amount of enzyme in the biofilm which has been demonst rated, allows us to obtain more sensitive devices.