Application of a mercapto-terminated binuclear Cu(II) complex modified Au electrode to improve the sensitivity and selectivity for dopamine detection

A new mercapto-terminated binuclear Cu(II) complex, [Cu2Cl2(mtboc)(2)(C12H8N2)(2)] [mtboc =2-( methylthio)benzo[d]oxazole-5-carboxylic acid] (Cu2), was synthesized and characterized by single-crystal X-ray diffraction studies. The Cu2 complex was then immobilized on the surface of Au electrodes through S-Au bonds to form a self-assembled monolayer. The electrochemical properties of the as-prepared Cu2- modified Au electrode (Au/Cu2) were investigated using cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry (DPV). Moreover, as a biomimetic sensor for the determination of dopamine (DA) and uric acid (UA), the Au/Cu2 electrode exhibited excellent electrocatalytic activity for the oxidation of DA with a faster electron-transfer rate (6.61 s(-1)). The DPV technique was used for the trace determination of DA. The dependence of current vs. concentration was linear from 0.2 to 30 mu M with a regression coefficient of 0.9975, and the detection limit of DA was similar to 0.08 mu M. Furthermore, the modified electrode clearly separated the DA signal from the interference effect of UA, thus realizing the simultaneous detection of DA and UA. Finally, the method was applied to the selective and precise analysis of DA in commercial injection and urine samples. (C) 2014 Elsevier B.V. All rights reserved.