Non-destructive integration of spark-discharge produced gold nanoparticles onto laser-scribed graphene electrodes for advanced electrochemical sensing applications

Gold nanoparticles (AuNPs) decorated graphene materials are preferable materials in a wide range of electrochemical applications, however, the current methods for preparing them have several limitations. Herein, we have developed a green, solution-free, and non-destructive method for the in-situ generation of AuNPs on laser-scribed graphene electrodes (LSGEs), addressing the limitations of traditional preparation methods. This novel technique, contrasting with the conventional solution-based electrochemical deposition, utilizes spark discharge to modify LSGEs, demonstrating superior performance in sensors and biosensors applications. Through comprehensive characterizations (scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM)), we observed significant distinctions in particle size, metal loading, stability, surface-to-volume ratio, and graphene quality between spark-discharge produced AuNPs (SP-AuNPs) and electrodeposition produced AuNPs (EC-AuNPs). The average particle sizes of the SP-AuNPs and EC-AuNPs are 10 nm and 38 nm, respectively. The SP-AuNPs modified LSGEs demonstrate exceptional electroanalytical performance in dopamine detection, with a broad detection range (0.6–90 µM) and low LOD (0.40 µM), further validated in human neuroblastoma cells SH-SY5Y. Our findings suggest that the spark discharge method represents a significant advancement in the synthesis of metal nanoparticle enhanced LSG electrodes, with broad implications for electrochemical sensing, biosensing, and biomedical applications.