CONSTRUCTION AND CHARACTERIZATION OF A MULTILAYER ENZYME ELECTRODE - COVALENT BINDING OF QUINOPROTEIN GLUCOSE-DEHYDROGENASE ONTO GOLD ELECTRODES

Multilayers of quinoprotein glucose dehydrogenase were assembled onto modified gold electrodes. As a primary modifier the bifunctional 3,3'-dithiodipropionic acid bis(N-hydroxysuccinimide ester) was chemisorbed. Glucose dehydrogenase was covalently bound to this activated electrode in a stepwise procedure. In the presence of glucose, the electrode functions as a sensor for electron accepters. Catalytic current, as observed for p-aminophenol, was used to characterize electrode performance. The dependence of the electrode response on the number of enzyme layers showed that the transition from a kinetic to a diffusion-limited sensor is reached at 6-7 enzyme layers. The response of multilayer electrode is stable over a broad range of pH and ionic strength of the bulk solution. It also shows good stability: after 2 months, 75% of its original activity remained.