Electrochemical detection of enzyme kinetics using a nanofluidic thin layer cell device

Amperometric detection is an attractive detection scheme for mico- and nanofluidic systems as it directly yields an electrical signal. However, this scheme is not often utilized because of its limited sensitivity. We overcome this limitation by employing a nanofluidic device consisting of a solution-filled cavity bounded by two closely spaced parallel electrodes that can amplify the current by repeatedly reducing and oxidizing electroactive species. Here we demonstrate the utility of such a device to measure enzyme kinetics in real time. We compare the conversion of p-cresol into methylquinone by tyrosinase using our nanofluidic device against a standard UV-Vis spectroscopic protocol.