Activity enhancement of a screen-printed carbon electrode by modification with gold nanoparticles for glucose determination

We have successfully developed a highly sensitive electrochemical sensor strip for a home blood-sugar monitoring device by a single-step straightforward procedure. The strip consists of a pair of screen-printed carbon electrodes, which work as counter and working electrodes in the chronoamperometric mode. To remedy the poor electrochemical activity of the printed carbon electrode, a small amount of gold nanoparticles was immobilized on the electrode. In the presence of glucose oxidase, the electrode modified with 2-nm particles showed about a five times higher sensitivity for glucose oxidation than the bare printed carbon electrode, and there was a significant dependence of the current on the particle diameter. Based on these observations, we have elucidated the glucose oxidation mechanism, which is comprised of two key factors, i.e. (1) electron transfer between the gold particles, and (2) electronic coupling between the gold particles and glucose oxidase.