Electrochemically selective detection of dopamine over serotonin by ITO/NiO(OH) electrode

Abstract

Abstract Dopamine and serotonin are the two key neurotransmitters that play vital roles in human central nervous system. It is essential to monitor the level of these neurotransmitters in our body. Enzyme-less or electrochemical detection of such bio-analytes are one of the accurate methods for this purpose. However, proper choice of the semiconductor electrode is crucial. To address this, thin films of nickel-oxy-hydroxide [NiO(OH)] was deposited on indium doped tin oxide (ITO) coated glass substrates using chronoamperometry. Thorough characterization of the deposited films were carried out using x-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, field emission scanning electron microscopy and UV-Vis spectroscopy. For the detailed electrochemical sensing of dopamine and serotonin, cyclic voltammetry (CV), steady-state amperometry, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were carried out in aqueous phosphate buffer solution (pH ~ 7). Electrochemical analyses for dopamine yielded high sensitivity of 11.12 µAµM− 1cm− 2 with a limit of detection of 0.55 µM, i.e., in sub µM level. Whereas, for serotonin, the value of sensitivity and limit of detection were found to be 0.04 µAµM− 1cm− 2 and 1.70 µM, respectively; which are inferior compared to dopamine detection. In addition, with the presence of serotonin as an interfering analyte, the performance of the developed electrode did not suppress much and effectively displayed the results in favour of dopamine; making the developed electrode dopamine selective.