PREPARATION AND AMPEROMETRIC GLUCOSE SENSITIVITY OF COVALENTLY BOUND GLUCOSE-OXIDASE TO (2-AMINOETHYL)FERROCENE ON AN AU ELECTRODE

A multilayer film consisting of glucose oxidase (GOx) and (2-aminoethyl)ferrocene (2-AF) as an electron mediator has been prepared on an Au electrode with the use of glutaraldehyde as a cross-linking agent. The amount of GOx and 2-AF deposited on the electrode is varied by changing the concentration of 2-AF relative to that of GOx in the preparation bath, and the highest deposition is obtained at an optimum concentration of 2-AF. Interestingly, the molar ratio of 2-AF to GOx in the film is similar to 10, independent of relative compositions of 2-AF to GOx in the preparation bath. The prepared electrode exhibits fast amperometric responses to glucose, its sensitivity being almost proportional to the amount of the immobilized GOx. Kinetic studies employing voltammetry and rotating disk electrode measurements suggest that the reaction rate is controlled by glucose oxidation by GOx and/or the electron mediation of 2-AF rather than diffusion of glucose in the film.