The proposed work involves the design and testing of new enzyme-based amperometric glucose sensors where electrical communication between the flavin redox centers of glucose oxidase and an electrode is achieved via a network of donor-acceptor relays chemically bound to a highly flexible, insoluble, high molecular weight polymer. Improvements in stability and selectivity will be pursued through the use of protective polymer coatings and novel enzyme immobilization procedures. The optimized sensors should have widespread technological applications in areas such as the clinical laboratory, veterinary health care, the research laboratory, and the food industry. With the use of protective polymer coatings to prevent fouling of the sensor in biological fluids, and electron transfer mediators which are covalently attached to an insoluble polymer to prevent their diffusion away from the electrode, the development of a reusable in vitro blood glucose monitor (for self-monitoring by diabetic patients) appears feasible. The polymeric relay systems are also amenable to needle-type probes which could be useful for many research applications.