Highly Sensitive Dopamine Biochemical Sensor Employing Pristine Electrodeposited Reduced Graphene Oxide

Dopamine is a crucial neurotransmitter, and atypical amounts have been linked to various neurological disorders. Nonetheless, the precise and efficient detection of dopamine is impeded by interference from structurally analogous biomolecules such as uric acid and ascorbic acid. A pristine reduced graphene oxide (RGO) on screen-printed gold electrode (SPGE) has been successfully developed for the sensitive and selective detection of dopamine. Reduced graphene oxide (RGO) was synthesised via the electrodeposition method, with manufacturing conditions optimised by varying the concentration of graphene oxide (GO) and the temperature of the water bath. The ideal conditions were determined to be 500 mgmL⁻1 of GO and 40°C, attributed to the elevated C:O ratio of RGO on SPGE, leading to superior electrochemical performance. The optimised RGO/SPGE sensor was evaluated for dopamine detection via square-wave voltammetry (SWV). The findings suggest a high sensitivity of 446.83 µA mM⁻¹cm⁻², with a detection limit (LOD) of 1.2 µM, demonstrating its ability to identify low quantities of dopamine. FTIR analysis demonstrated a significant reduction of GO and the interaction between dopamine and the RGO-modified surface, corroborating the observed electrochemical changes. Electrochemical impedance spectroscopy (EIS) was employed to examine the interfacial charge transfer characteristics of the electrode at different dopamine concentrations. The reduction in charge transfer barrier with rising dopamine concentrations indicates enhanced electron transfer kinetics. The sensor exhibited significant selectivity for dopamine, distinguishing it from interfering substances such as uric acid (UA) and ascorbic acid (AA). Moreover, the sensor exhibited remarkable stability, retaining 91.75% of its initial current response. The sensor has exceptional reproducibility and repeatability, with RSD values of 4.04% and 3.28% (n = 3), respectively. These findings underscore the optimised RGO/SPGE sensor's promise as a reliable and economical electrochemical sensing platform, particularly in biological matrices.