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 electro de in a stepwise procedure. In the presence of glucose, the electrode functions as a sensor for electron accepters. Catalytic current, as ob served for p-aminophenol, was used to characterize electrode performan ce. The dependence of the electrode response on the number of enzyme l ayers showed that the transition from a kinetic to a diffusion-limited sensor is reached at 6-7 enzyme layers. The response of multilayer el ectrode is stable over a broad range of pH and ionic strength of the b ulk solution. It also shows good stability: after 2 months, 75% of its original activity remained.