A 96-Well Electrochemical Method for the Screening of Enzymatic Activities

The rapid electrochemical screening of enzyme activities in bioelectronics is still a challenging issue. In order to solve this problem, we propose to use a 96-well electrochemical assay. This system is composed of 96 screen-printed electrodes on a printed circuit board adapted from a commercial system (carbon is used as the working electrode and silver chloride as the counter/reference electrode). The associated device allows for the measurements on the 96 electrodes to be performed within a few seconds. In this work, we demonstrate the validity of the screening method with the commercial laccase from the fungus Trametes versicolor. The signal-to-noise ratio (S/N) is found to be the best way to analyze the electrochemical signals. The S/N follows a saturation-like mechanism with a dynamic linear range of two decades ranging from 0.5 to 75 ng of laccase (corresponding to enzymatic activities from 62 x 10(-6) to 9.37 x 10(-3) mu mol min(-1)) and a sensitivity of 3027 mu g(-1) at +100 mV versus Ag/AgCl. Laccase inhibitors (azide and fluoride anions), pH optima, and interfering molecules could also be identified within a few minutes.