Deactivation of bilirubin oxidase by a product of the reaction of urate and O2

The wired bilimbin oxidase (BOD) bioelectrocatalyst is superior to pure platinum as an electrocatalyst of the four-electron electroreduction of O-2 to water. Not only is its overpotential for O-2 reduction lower, but unlike platinum, it is not affected by organic compounds like glucose. The wired BOD-coated carbon cathode operates for > 1 week at 37degreesC in a glucose-containing physiological buffer solution. One of its key applications would be in a glucose-O-2 biofuel cell, which would operate in living tissues. The cathode is, however, short-lived in serum, losing its electrocatalytic activity in a few hours. Here we show that the damaging serum component is a product of the reaction of urate and dissolved oxygen. Exclusion of urate, by application of Nafion(TM) film on the cathode, improves the stability in serum. (C) 2004 Elsevier B.V. All rights reserved.