AMPEROMETRIC GAS-DIFFUSION ENZYME ELECTRODE

An amperometric enzyme gas-diffusion electrode has been developed whic h combines a porous, air breathing gas-diffusion electrode with an enz yme [glucose oxidase (GOD)] immobilized with Nafion into its porous ca talytic layer. The catalytic layer contains pyrolyzed Cotetramethoxyph enylporphyrine (CoTMPP), which is very active towards the electrochemi cal oxidation of H2O2. The behavior of this electrode was investigated when the oxygen needed for the enzymatic reaction was supplied from t he air (in the gas phase) through the porous structure of the gas-diff usion electrode. It was shown that in the presence of the substrate (g lucose), the amperometric signal obtained in this mode of operation wa s much higher than that obtained when only the oxygen dissolved in the electrolyte was involved in the enzymatic reaction. The developed enz yme gas-diffusion electrode allows a versatile and rapid change in the O-2 concentration in the zone where the enzymatic reaction is taking place. This electrode can be used as a model system for the investigat ion of the influence of O-2 On the performance of both the peroxide or the mediated enzyme electrodes in an effort to develop oxygen indepen dent biosensors.