Study on Dopamine Electrochemical Sensing Based on Au@MoS<sub>2</sub>

Dopamine (DA) is a vital neurotransmitter, and accurate detection of its concentration is critical for both clinical diagnostics and neuroscience research. Due to its electrochemical activity, DA is commonly detected using electrochemical methods, which are favored for their simplicity, fast response time, and suitability for in vivo analysis. In this work, a highly sensitive DA electrochemical sensor was developed using an Au@MoS2 composite, created by modifying molybdenum disulfide (MoS2) nanosheets with gold nanoparticles through HAuCl4 reduction, and it was aimed at enhancing DA adsorption and improving detection performance. Scanning Electron Microscopy (SEM), transmission electron microscopy (TEM), Energy Dispersive Spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray Diffraction (XRD) confirmed the successful synthesis of Au@MoS2 and the uniform distribution of gold nanoparticles across the MoS2 nanosheets. Then, the electrochemical characterization demonstrated that the Au@MoS2/GCE exhibited distinct oxidation peaks in a 10 μmol·L–1 DA solution, with significantly enhanced electrochemical activity compared to both unmodified GCE and pristine MoS2. Furthermore, differential pulse voltammetry (DPV) further revealed a strong linear relationship between DA concentration and the current response in the range of 800 nmol·L–1 to 10 μmol·L–1, with a low detection limit (LOD) of 78.9 nmol·L–1 (S/N = 3). Additionally, the sensor showed excellent selectivity against other interfering substances. Moreover, the laser-induced Au@MoS2 (LIAu@MoS2), with its abundance of negatively charged surface defects, enabled the ultra-sensitive detection of the ultra-low concentrations of DA. In conclusion, the successfully fabricated Au@MoS2 based sensor offers advantages such as low cost, ease of operation, and scalability, making it a promising candidate for biosensing applications due to its enhanced DA detection capabilities.