Fabrication of electrochemical sensor based on polyzincon nanolayer for dopamine detection

In this research, electrochemical sensor based on the polyzincon-modified glassy carbon electrode was fabricated to detect the dopamine. For this purpose, the glassy carbon electrode was modified by using cyclic voltammetry between -1 and 2.2 V and scan rate of 0.07 V/s for 6 cycles in a phosphate buffer (0.1 M) at pH 7 containing 0.1 mM zincon. Investigation on electrocatalytic activity and the electrochemical active surface showed that the surface area has increased for the modified electrode as compared to the glassy carbon electrode. The electrochemical impedance spectroscopy indicated the enhanced electron transfer between the electrode and redox probe for the polyzincon modified electrode. Based on the results, the anodic and cathodic peak currents increased with the scan rates and linear relation between peak current and scan rate and its square root indicated a dual character containing diffusion and adsorption-controlled processes on the surface. Detection of dopamine on surface of the modified electrode by differential pulse voltammetry method showed two linear range of 0.2-1 μM and the range of 1-100 μM with a limit of detection of 0.06 μM. Also, relative standard deviation for 5 replicates measurements in 20 μM dopamine solution was calculated as 4.5%. The designed sensor has advantages such as simplicity, low cost, high accuracy and sensitivity, and a suitable limit of detection that is able to compete with the latest electrodes in dopamine detection.