A bioanalytical tool for monitoring athlete health and detecting performance-enhancing drugs: An electrochemical biosensor based on graphene oxide

This study presents the development of an electrochemical immunosensor based on a nanocomposite of nitrogendoped reduced graphene oxide (N-rGO) and copper oxide (CuO) for the detection of erythropoietin (EPO). The sensor demonstrated remarkable stability, repeatability, and biocompatibility, with a linear detection range of 10-2 ng/L to 104 ng/L and a detection limit of 3 pg/L. The sensor exhibited a relative standard deviation of less than 4.4 % for five electrodes detecting 1.0 ng/L EPO, indicating excellent repeatability. The sensor maintained a stable electrochemical current response with less than 3.9 % change after 30 days, demonstrating its long-term stability. The sensor's performance was validated using human serum samples, showing EPO recovery rates ranging from 90.00 % to 98.00 %. These findings suggest that the immunosensor is suitable for clinical applications, contributing to advancements in bioanalytical monitoring and the detection of performance-enhancing drugs.