Simultaneous determination of serotonin, dopamine, and ascorbic acid at a glassy carbon electrode modified with chitosan-alginate hydrogel and reduced graphene oxide

Detection of biologically active components, such as ascorbic acid, dopamine, and serotonin, is significant from the perspective of biomedicine, particularly in the process of disease diagnosis and in the quality control of commercial pharmaceutical products. In this work, a novel electrochemical sensor was developed by modifying a glassy carbon electrode with a hydrogel composed of a polyelectrolyte complex of alginate and chitosan, along with the addition of electrochemically reduced graphene oxide. This biocompatible sensor was applied for the simultaneous determination of ascorbic acid, dopamine, and serotonin using adsorptive square wave voltammetry. The modified GCE demonstrated an excellent electrochemical response towards the target analytes, thanks to the enhanced adsorption of the analytes on the surface of the electrode, facilitated by favorable interactions between analytes and the modifiers. This approach increased the electrode's active surface area and ensured excellent electrode response. The sensor exhibited a broad linear range of the anodic current relative to analyte concentration, achieving low detection limits of 0.094 mu M, 4.18 nM and 3.23 nM for ascorbic acid, dopamine and serotonin, respectively. Additionally, the proposed sensor exhibited good stability, reproducibility of results, selectivity, as well as effectiveness, in the determination of target biological compounds in real sample matrices.