An electrochemical biosensor based on graphene oxide-modified glucose oxidase for non-invasive glucose detection in multiple biofluids

Purpose Monitoring and controlling blood glucose levels is central to diabetes management. To address the pain and infection risks associated with conventional invasive detection methods, this study aims to present a chitosan (CS)/glucose oxidase (GOx)-graphene oxide (GO)/screen-printed carbon electrode (SPCE) electrochemical biosensor that enables direct electron transfer between GOx and the SPCE, allowing noninvasive glucose detection in complex biological fluids. Design/methodology/approach The sensor was fabricated using SPCE as the substrate, which was pretreated to significantly enhance electrochemical performance – reducing electron transfer resistance by over 50% and increasing peak current response by more than 1.5-fold. Subsequently, the GOx-GO composite was immobilized onto the working electrode surface, followed by drop-casting of CS to form a selective diffusion barrier. Findings The biosensor was characterized using multiple electrochemical techniques, demonstrating a linear detection range of 0.01–2.4 mM, a low limit of detection (LOD) of 0.01 mM and a sensitivity of 5.015 µA·mM−1cm−2. It also exhibited excellent repeatability (relative standard deviation = 2.2% for n = 4) and long-term stability (⩾14 days). In addition, the sensor exhibited excellent selectivity and anti-interference capability in glucose detection across various human biofluids, with high accuracy and reliability in analytical results. Originality/value In summary, the developed CS/GOx-GO/SPCE biosensor offers a simple, low-cost fabrication process and demonstrates great potential for practical applications in noninvasive, painless glucose monitoring, owing to its high sensitivity, low LOD and wide linear range.