Heterobimetallic Oxide CoCu₂O₃ Ultrathin Films on FTO Glass: Enzyme-Free Biosensor for Neurotransmitter Dopamine and Serotonin with Factual Analytes

Recognition and monitoring of neurotransmitters like dopamine (DA) and serotonin (SE) have been subjects of great importance in the past few years. Disorder of the quantity of these neurotransmitters may have a detrimental effect on human health. Now, the development of a well-organized monitoring probe for DA and SE detection is vital. Herein, an efficient electrochemical sensor was constructed with copper and cobalt on FTO (fluorine-doped tin oxide) to act as an enzyme-free biosensor for the first time. Structure, composition, and surface morphology of CoCu 2 O 3 were examined by X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy (UV–vis), and atomic force microscopy techniques. Endogenous measurements of DA, SE, and the nature of the electrode were demonstrated using voltammetry and amperometry studies, which showed impressive electroanalytical performance in the detection of DA and SE separately and simultaneously. The biosensing probe shows a detection limit, and its sensitivity is around 0.206 and 0.237 μM and 65.12 and 61.12 μAμM –1 cm –2 for DA and SE, respectively. The fabricated sensor has excellent stability, repeatability, and reproducibility of FTO/CoCu 2 O 3 thin film due to its uniform active sites of the grains, suggesting a future scope in biosensing. It exhibits good selectivity in interference studies with different interferents. With the successful recognition of DA in dopamine hydrochloride injections, DA and SE in goat and hen blood serum samples were tested using the electrode fruitfully. A UV–vis experiment was performed with the reaction mixture before and after electrochemical analysis that proved the presence of oxidized products of DA and SE. The time-dependent density-functional theory method of calculation was utilized to predict the probable structure of intermediates with plausible mechanisms. It is a promising platform for DA and SE biosensing with high efficacy.