Low-potential amperometric detection of dopamine based on MnO2 nanowires/chitosan modified gold electrode

In this research, a manganese dioxide (MnO2) nanowires/chitosan-modified gold (Au) electrode was successfully fabricated for amperometric determination of dopamine (DA) at a very low working potential (0.00V vs. SCE). The electrochemical properties of the modified Au electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The detection scheme was proposed to involve two major reactions: the chemical oxidation of DA to o-dopaminoquinone by MnO2 nanowires, and then the electro-reduction of o-dopaminoquinone to DA at a low working potential (0.00V vs. SCE), resulting in a distinct reduction response current. The modified Au electrode displays good amperometric response to DA in a wide concentration range 0.10 mu M to 1.10 mM. The fabrication of MnO2 nanowires/chitosan-modified Au electrode is simple and highly reproducible (RSD = 3.8%, n = 5). It exhibits excellent analytical performance in terms of low working potential (0.00V vs. SCE), long shelf-life (90% of its initial response after 1-month storage) and high repeatability (RSD = 2.2%, n = 5). Finally, it was applied to determine DA in real samples directly with high accuracy (99%) and good recovery (99.7-103%), confirming its promising application in routine DA analysis. (C) 2012 Elsevier Ltd. All rights reserved.