Enhanced Microbial Sensing via Resazurin Reduction Catalyzed by Graphene Oxide, A Versatile Approach for Diagnostics and Electrochemical Applications

Resazurin is a cell viability phenoxazine dye widely employed for bacterial monitoring, as its colorimetric and fluorometric conversion reflects microbial metabolic activity. In this work, we demonstrate that graphene oxide (GO), a two-dimensional nanomaterial with high surface reactivity, markedly accelerates the reduction of resazurin in the presence of Staphylococcus aureus, enabling rapid microbial detection at non-cytotoxic concentrations. Importantly, this GO-mediated enhancement directly supports applications in environmental toxicology. Rapid identification of bacterial contaminants in water and environmental samples is essential for assessing toxic exposures, such as those caused by pathogenic contamination of drinking water. By lowering the time required to detect viable bacteria, the GO–resazurin system provides a sensitive and practical tool for evaluating environmental quality and potential health risks associated with microbial contamination. While the GO and resazurin lack interaction in the absence of cells, the S. aureus metabolism specifically increases electron shuttling of the probe towards the carbon material compared to other tested bacteria. Furthermore, with a comprehensive spectrofluorimetric characterization of resazurin/GO/bacteria interaction, we demonstrate an enhanced resorufin color loss that unveils potential applications in revolutionizing environmental monitoring, pollutant degradation, and microbial fuel cells design. These findings highlight the role of GO as a catalytic enhancer, enabling more sensitive early warning systems in exposure assessment, improving accuracy in pollution monitoring, and facilitating efficient and sustainable remediation strategies for toxic substances removal.