Graphene oxide-Ag/poly-L-lysine modified glassy carbon electrode as an electrochemical sensor for the determination of dopamine in the presence of ascorbic acid

The graphene oxide (GO) and Ag hybrid matrix GO-Ag were coated onto the glassy carbon electrode (GCE) surface, then, poly-L-lysine films (PLL) were prepared by electropolymerization with cyclic voltammetry (CV) method to prepare GO-Ag/PLL modified glassy electrode (GO-Ag/PLL/GCE). The electrochemical sensor based on GO-Ag/PLL/GCE was used to sensitively determine dopamine (DA) in the presence of ascorbic acid (AA). Electrochemical behaviors of DA and AA mixture were investigated on GO-Ag/PLL/GCE by CV, which gave a baseline separation of the oxidation peak potential by 232 mV. So the modified electrode was suitable for determine of DA in the presence of AA. The GO-Ag/PLL/GCE electrode improved the DA electrochemical catalytic oxidation, which demonstrates that GO-Ag/PLL/GCE has a remarkable electrocatalytic activity towards the oxidation of DA. Moreover, PLL modified electrodes have good stability, excellent permselectivity, more active sites and strong adherence to electrode surface, which enhanced electrocatalytic activity. Under the optimized conditions, there were linear relationships between the peak currents and the concentrations in the range of 0.1-10 mu M for DA, with the limit of detection (LOD) (based on S/N = 3) of 0.03 mu M for DA. The GO-Ag/PLL/GCE sensor was successfully applied to the determination of DA in bovine serum samples and showed high selectivity, sensitivity, and reproducibility. (C) 2015 Elsevier B.V. All rights reserved.