CuO@GCN nanocomposite modified SPCE for sensitive and selective detection of caffeine

Abstract

Caffeine (1,3,7-trimethylxanthine), a naturally occurring alkaloid extensively consumed worldwide, and its excessive consumption is associated with adverse physiological responses including insomnia, cardiovascular stress, and anxiety disorders. This study is designed to develop an electrochemical based approach for the quantitative analysis of caffeine in real samples. Graphitic carbon nitride (GCN) and copper oxide nanoparticles (CuO) synthesized by pyrolysis approach and co-precipitation method, respectively. Then graphitic carbon nitride-based copper oxide nanocomposite (CuO@GCN NC) was synthesized by hydrothermal process. The successfully synthesis and nanostructure of CuO-GCN NC was confirmed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR). The heterostructured CuO@GCN loaded on surface of screen-printed carbon electrode (SPCE) provided abundant electroactive sites and promoted rapid interfacial electron transfer, resulting in enhanced electrochemical performance toward caffeine oxidation. A linear calibration plot was obtained for caffeine detection in phosphate buffer solution at pH 7.0 over the concentration range of 0.5–90 µM. The CuO@GCN/SPCE sensor showed a sensitivity of 0.11 µA µM^− 1. The limit of detection was calculated using the equation LOD = 3σ/S, where σ and S represents the standard deviation and slope of the calibration curve. Based on this method, the detection limit (LOD) was found to be 0.017 µM. The developed method showed excellent stability and reproducibility with RSD of less than 5%. These findings demonstrate that the CuO@GCN/SPCE provides a simple, cost-effective, and reliable electrochemical sensing platform with significant potential for routine food quality monitoring and real-time caffeine analysis.