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

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.