Graphitic Carbon Nitride Nanosheets-Based Ratiometric Fluorescent Probe for Highly Sensitive Detection of H₂O₂ and...

Graphitic carbon nitride (g-C₃N₄) nanosheets, an emerging graphene-like carbon-based nanomaterial with high fluorescence and large specific surface areas, hold great potential for biosensor applications. Current g-C₃N₄ nanosheets based fluorescent biosensors majorly rely on single fluorescent intensity reading through fluorescence quenching interactions between the nanosheets and metal ions. Here we report for the first time the development of a novel g-C₃N₄ nanosheets-based ratiometric fluorescence sensing strategy for highly sensitive detection of H₂O₂ and glucose. With o-phenylenediamine (OPD) oxidized by H₂O₂ in the presence of horseradish peroxidase (HRP), the oxidization product can assemble on the g-C₃N₄ nanosheets through hydrogen bonding and π-π stacking, which effectively quenches the fluorescence of g-C₃N₄ while delivering a new emission peak. The ratiometric signal variations enable robust and sensitive detection of H₂O₂. On the basis of the glucose converting into H₂O₂ through the catalysis of glucose oxidase, the g-C₃N₄-based ratiometric fluorescence sensing platform is also exploited for glucose assay. The developed strategy is demonstrated to give a detection limit of 50 nM for H₂O₂ and 0.4 μM for glucose, at the same time, it has been successfully used for glucose levels detection in human serum. This strategy may provide a cost-efficient, robust, and high-throughput platform for detecting various species involving H₂O₂-generation reactions for biomedical applications.