AMPEROMETRIC PROCESSES WITH GLUCOSE-OXIDASE EMBEDDED IN THE ELECTRODE

Amperometric biosensors are based on processes that allow measured currents to be directly related to concentrations of unknown substrate sample. Mechanisms often depend on an electron-transfer mediator and on redox or dehydrogenase enzyme catalysis using the enzyme in the bathing phase. This study answers two questions: Can an electrode-embedded enzyme remain active? Can an embedded enzyme contribute roughly the same catalytic current as the corresponding electrode using enzyme homogeneously distributed in the solution? The redox enzyme glucose oxidase was embedded directly in a graphite powder electrode with poly(vinylchloride) as a binder. Ferrocene monocarboxylic acid was the electron-transfer mediator. The enzyme electrode remained active and stable for more than a year in a dried state in a refrigerator. The measured electrochemical catalytic current obeyed the classical theory that assumes constant catalyst activity which, in this case, is on the electrode surface or just inside the electrode.