▎ 摘　　要

A promising electrochemical biosensor for simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA) was fabricated by electrochemical deposition of MgO nanobelts on a graphene-modified tantalum wire (denoted as MgO/Gr/Ta) electrode. The MgO nanobelts and graphene were verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performances of the electrodes were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The CV results show that AA, DA and UA could be detected simultaneously using MgO/Gr/Ta electrode with peak-to-peak separation of 300 mV, 147 mV and 447 mV for AA-DA, DA-UA and AA-UA, respectively. In the threefold co-existence system, the linear calibration plots for AA, DA and UA were obtained over the concentration range of 5.0-350 mu M, 0.1-7 mu M and 1-70 mu M with detection limits of 0.03 mu M, 0.15 mu M and 0.12 mu M, respectively. The modified electrode shows excellent selectivity, good sensitivity and good stability, making it attractive as a sensor for simultaneous detection of AA, DA and UA in biological fluids. (C) 2015 Elsevier Ltd. All rights reserved.