PLATINUM-CATALYZED ENZYME ELECTRODES IMMOBILIZED ON GOLD USING SELF-ASSEMBLED LAYERS

The bonding of enzymes to self-asembled monolayers (SAMs) of alkanethi ols onto gold electrode surfaces is exploited to produce an enzyme bio sensor, The attachment of glucose oxidase to a SAM of 3-mercaptopropio nic acid was achieved using carbodiimide coupling. The resultant biose nsor showed good sensitivity to glucose and a large dynamic range when measured amperometrically via the p-benzoquinone mediator. On the oth er hand, subsequent platinization of the enzyme-SAM: electrode allowed hydrogen peroxide produced in the enzyme reaction to be detected dire ctly, thus obviating the need for an artificial redox mediator. The pe rformance of such sensors constructed on bulk gold electrodes was eval uated and finally compared to that of some preliminary thin-film gold electrodes. Biosensors constructed using the two alternative electrode surfaces have quite different sensitivities, thus reflecting the infl uence of the anchoring surface on the performance of the biosensor.