A gold-nanoparticle/horizontal-graphene electrode for the simultaneous detection of ascorbic acid, dopamine, uric acid, guanine, and adenine

A novel electrochemical biosensor for the simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA), guanine (GUA), and adenine (ADE) was fabricated by the electrochemical deposition of Au nanoparticles onto a horizontal-graphene-modified tantalum wire (Au/HG) electrode. The graphene layer was grown using hot-filament chemical vapor deposition and shows high potential as a novel biosensor. The incorporation of Au nanoparticles and graphene was confirmed by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. The electrochemical performance of the electrodes was characterized by electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). DPV reveals that AA, DA, UA, GUA, and ADE are detected simultaneously using the Au/HG electrode, exhibiting peaks at − 0.101, 0.112, 0.252, 0.608, and 0.874 V, respectively. In a system containing these five analytes, linear calibration plots for AA, DA, UA, GUA, and ADE were obtained over the 4–600, 0.4–20, 0.6–40, 6–500, and 0.6–40 μM ranges, respectively, with corresponding detection limits of 1.76, 0.02, 0.57, 2.5, and 0.42 μM, respectively. The Au/HG layer shows good electrocatalytic activities toward the redox reactions of AA, DA, UA, GUA, and ADE. This sensing electrode exhibited good selectivities, excellent sensitivities, high stabilities, and low detection limits.