Electrochemically Assaying Dopamine with p-Doped Silicon Nanowires

Abstract

Neuroblastoma, a pediatric cancer, is characterized by high urinary excretion of dopamine (DA). Silicon nanowires (SiNWs), which are nontoxic and known to resist surface fouling in biological samples, were investigated for practical use as working electrode materials to assay dopamine. Undoped, p-doped, and n-doped SiNWs were deposited onto glassy carbon electrodes (GCEs) and used to measure dopamine in aqueous solution. Within this series, p-doped SiNWs had the highest sensitivity in the series and are the focus of this study. Optimum measurements were obtained at pH 5.0. Cyclic voltammetry (CV) determination of dopamine showed that oxidation at +0.4801 V versus Ag/AgCl provided the highest sensitivity and also for chronoamperometric (CA) analysis. A calibration curve using chronoamperometry showed a linear (R2 = 0.9896) range from 50 to 900 µM. Randles-Sevçik analysis showed that the interaction of dopamine with the electrode surface was diffusion controlled reversibly with coefficients (D) equal to 2.77 × 10−5 and 2.01 × 10−5 cm2·s−1 for the oxidation and reduction potentials, respectively. The sensor was demonstrated to be selective in the presence of uric acid, acetaminophen, H2O2, folic acid, and glucose.