A xanthine oxidase colloidal gold enzyme electrode for amperometric biosensor applications

An electrode has been prepared based on xanthine oxidase adsorbed to colloidal gold and evaporated onto the surface of glassy carbon. This electrode responds to xanthine or hypoxanthine in the absence of added mediator by electrochemical oxidation of the enzymatic oxidation product, uric acid, at the electrode surface. The electrode can also be used in the presence of an electron transfer mediator to detect other substrates for xanthine oxidase such as 4-hydroxypyrimidine.