A dopamine electrochemical sensor based on gold nanoparticles/over-oxidized polypyrrole nanotube composite arrays

A novel sensor based on a gold nanoparticles (Au NPs)/over-oxidized polypyrrole (OPPy) nanotube (NT) composite arrays electrode proved to be highly effective for electrochemical determination of dopamine (DA). Oriented Au NPs/OPPy NT arrays were electrodeposited by using zinc oxide (ZnO) nanowire (NW) arrays as templates. The morphologies of ZnO NW arrays, OPPy NT arrays, and Au NPs/OPPy NT arrays were studied by scanning electron microscopy (SEM). Electrochemical behaviors of the modified electrodes were characterized by cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. The Au NPs/OPPy NT arrays electrode had strong catalytic activity toward the oxidation of DA. The peak currents obtained from SWV increased linearly with increasing DA concentrations in the range of 25 nM to 2.5 μM. The simultaneous analysis of ascorbic acid (AA) and DA was investigated, the results demonstrated that the Au NPs/OPPy NT arrays electrodes exhibited good selectivity and sensitivity for the determination of DA without interference by the oxidation of AA.