Utilization of gold nanoparticles-bismuth vanadate photocatalyst-based photoelectrochemical sensor for caffeine detection in biological samples of athletes: A sporting perspective

This study presents a photo sensor for caffeine (CA) detection, employing gold nanoparticles (Au NPs) immobilized on bismuth vanadate on indium tin oxide substrate (Au-BiVO 4 /ITO). The characterization of the Au-BiVO 4 /ITO electrode was investigated by surface analysis, crystallography and electrochemical methods. The incorporation of Au NPs into the BiVO 4 structure has significantly increased the photocatalytic performance of the material, especially its photocurrent response. This modification has increased the photocurrent from the initial value of 200 µA to more than 300 µA. The Au-BiVO 4 /ITO PEC sensor demonstrated enhanced photocurrent responses to CA under visible light, compared to BiVO 4 /ITO. Under optimized conditions, the PEC sensor showed a linear correlation between analytical signal and CA concentration from 0.3 to 270 μM, with obtained detection limit of 0.08 μM. Using the standard addition way, it measured CA in serum and urine samples from athletes, achieving average recovery rates of 99.4 % in serum and 97.8 % in urine, which indicates high accuracy. Moreover, the results showing strong agreement with standard HPLC analysis and demonstrating high recovery efficiency. Furthermore, the sensor demonstrated excellent performance with acceptable figure of merit for CA measurement, making it suitable for reliable analytical applications in biological samples.