Glutathione (GSH) plays a crucial role in cellular redox homeostasis, immune regulation, and metabolic processes, and its abnormal expression is closely associated with various diseases. Therefore, the development of sensitive and reliable analytical strategies for GSH detection is of significant importance for disease diagnosis and biomedical research. In this work, a photoelectrochemical (PEC) sensing platform based on a Cu2O-modified electrode was developed for the sensitive detection of GSH. Owing to its p-type semiconductor characteristics, Cu2O exhibits strong resistance to interference from reductive substances in complex biological environments. More importantly, Cu2O can react with the thiol group of GSH through a redox process, leading to structural variation of the Cu2O surface and consequently inducing a measurable change in the photocurrent signal. The Cu2O photoelectrode was fabricated on an indium tin oxide (ITO) substrate via electrodeposition and systematically characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and photoelectrochemical measurements. Experimental conditions, including electrodeposition time, applied bias, and reaction time, were optimized to achieve optimal sensing performance. Under the optimized conditions, the PEC sensor exhibited a linear response toward GSH in the concentration range of 1 - 40 μM with a detection limit of 0.38 μM (S/N = 3). In addition, the sensor demonstrated excellent selectivity against various interfering biomolecules and showed satisfactory reproducibility. This study provides a simple and effective PEC sensing strategy for GSH detection and highlights the potential of Cu2O-based photoelectrodes for biochemical analysis and biomedical applications.
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