Polyaniline supported MWCNT/TiO2/Ag3PO4 nanocomposite for electrochemical determination of dopamine

Dopamine (DA) is a neurotransmitter that plays a vital role in the brain's reward and pleasure centers which are also involved in regulating movement and emotional responses and can cause various disorders if increased or decreased from its optimal concentration. Thus, it is essential to develop rapid and simple methods for the determination of its concentration. In the present study, polyaniline-supported MWCNT/TiO 2 /Ag 3 PO 4 nanocomposite was synthesized by in situ polymerization method and its structure and composition were characterized by X-ray diffraction (XRD), and Fourier transform infrared (FTIR). The electrochemical behaviors of TiO 2 , MWCNT, Ag 3 PO 4 , MWCNT/TiO 2 , TiO 2 /Ag 3 PO 4 , MWCNT/TiO 2 /Ag 3 PO 4 , and PANI(MWCNT/TiO 2 / Ag 3 PO 4 ) modified Pt electrodes were studied using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) in the presence of 2 mM K 3 Fe(CN) 6 /0.1 M KCl. The result showed that PANI-supported MWCNT/TiO 2 /Ag 3 PO 4 nanocomposite was a more electroactive substrate. The same was observed towards the oxidation of dopamine due to the high electrocatalytic activity and high surface area of PANI. At the optimized condition (pH 4), the electrode was used as an electrochemical sensor for the determination of dopamine in a standard solution. The electrode exhibited a linear range (10–80, 5–120 μmol L −1 ), detection limits (1.51, 2.76 μmol L −1 (3σ/s) and sensitivity (4.31, 1.025 = slope/area) using Differential Pulse Voltammetry (DPV) and CV, respectively. DA followed a quasi-reversible process and its diffusion coefficient was 1.61*10 −5 cm 2 /. The proposed sensor showed good selectivity towards DA in the presence of other electroactive compounds like ascorbic acid and is a promising DA-sensor due to its low detection limit, high sensitivity and good selectivity.