The redox mediator hexacyanof errate(II/III) has been electrodeposited on nickel by anodization of porous nickel electrodes In aqueous electrolytes containing hexacyanoferrate(II) Ions. Cyclic voltammetry of the resultant nickel hexacyanoferrate films reveals the presence of two peaks corresponding to the hexacyanoferrate(II/III) redox couple. The redox films catalyze the oxidation of reduced nicotinamide adenine dinucleotide (NADH) with a decrease In overvoltage of ~150 mV compared to unmodified electrodes. The steady-state current response at +0.2 V vs. Ag/AgCl In 0.1 M sodium perchlorate containing 0.01 M sodium phosphate, pH 7.5, Increases linearly with NADH concentration. The nickel hexacyanoferrate films are capable of reoxidlzlng enzymlcally generated NADH. In the presence of soluble or immobilized alcohol dehydrogenase, a rapid rise In current was observed after addition of ethanol, reaching steady state within 30-60 s. The hexacyanoferrate-modHied nickel electrode possesses many of the features desirable for use as an amperometric sensor for oxldoreductase substrates. © 1987, American Chemical Society. All rights reserved.
