(110)-Exposed Gold Nanocoral Electrode as Low Onset Potential Selective Glucose Sensor

ABSTRACT A straightforward electrochemical deposition process was developed to grow gold nanostructures, including nanocoral, nanothorn, branched belt, and nanoparticle, on carbon electrodes by reducing HAuCl4 under constant potentials inmixtures containing CTAC and/or NaNO3. Among the nanostructures, the quasi-one-dimensional nanocoral electrode showed the highest surface area. Because of this, it provided excellent electrochemical performances in cyclic voltammetric (CV) studies for kinetic-controlled enzyme-free glucose oxidation reactions. In amperometric studies carried out at 0.200 V in PBS (pH 7.40, 0.100 M), the nanocoral electrode showed the highest anodic current response. It also offered the greatest sensitivity, 22.6 µAmM-1cm-2, an extended linear range, 5.00 × 10-2 mM to 3.00 × 101 mM, and a low detection limit, 1.00 × 101 µm among the electrodes investigated in this study. In addition, the glucose oxidation by the nanocoral electrode started at-0.280 V, more negative than the one of using a commercial Au electrode as the working electrode. This is attributed to the presence of exposed Au (110) surfaces on the electrode. The feature was applied to oxidize glucose selectively in the presence of ascorbic acid (AA) and uric acid (UA), common interferences found in physiological analytes. With an applied voltage at-0.100 V, the AA oxidation (started at-0.080 V) can be avoided while the glucose oxidation still provides a significant response