Parameters important in fabricating enzyme electrodes using self-assembledmonolayers of alkanethiols

The fabrication of enzyme electrodes using self-assembled monolayers (SAMs) has attracted considerable interest because of the spatial control over th e enzyme immobilization. A model system of glucose oxidase covalently bound to a gold electrode modified with a SAM of 3-mercaptopropionic acid was in vestigated with regard to the effect of fabrication variables such as the s urface topography of the underlying gold electrode, the conditions during c ovalent attachment of the enzyme and the buffer used. The resultant monolay er enzyme electrodes have excellent sensitivity and dynamic range which can easily be adjusted by controlling the amount of enzyme immobilized. The ma jor drawback of such electrodes is the response which is limited by the kin etics of the enzyme rather than mass transport of substrates. Approaches to bringing such enzyme electrodes into the mass transport limiting regime by exploiting direct electron transfer between the enzyme and the electrode a re outlined.