Dopamine neurotransmitter determination using graphite sheet–graphene nano-sensor

In this study, graphene oxide was electrochemically deposited and reduced on a graphite sheet. The electrode surface morphology was studied by scanning electron microscopy. The performance of the modified electrode in detecting dopamine was investigated. The results indicate that the electrodeposition of reduced graphene oxide onto the electrode surface increases the dopamine oxidation current, decreases the overpotential, and reduces the charge transfer resistance. The efficiency of dopamine detection by this modified electrode was evaluated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The effects of electrolyte pH, potential scan rate, electrode reproducibility, and selectivity were investigated. Furthermore, for the stability test, the chronoamperometry technique was performed, and the results demonstrated that the electrode has excellent stability. This electrode provides a low detection limit of 68 nM and a wide linear range from 0.1 to 1000 µM. For real sample analysis, measurements were successfully conducted on a dopamine ampule as a cardiovascular drug. This nanosensor takes advantage of a simple and rapid fabrication process at a low cost.