Ruthenium Ion-Complexed Carbon Nitride Nanosheets with Peroxidase-like Activity as a Ratiometric Fluorescence Probe for the Detection of Hydrogen Peroxide and Glucose.

Detection of hydrogen peroxide is of great significance for clinical diagnosis and biomedical research. Ratiometric detection represents an effective method that is generally based on horseradish peroxidase. In the present study, ruthenium ion-complexed carbon nitride (Ru-C3N4) nanosheets are found to serve as a peroxidase mimic and can catalyze the conversion of o-phenylenediamine to fluorescent 2,3-diaminophenazine in the presence of H2O2. The produced 2,3-diaminophenazine also results in the apparent quenching of the Ru-C3N4 photoluminescence due to the inner filter effect. These unique characteristics can be exploited for the construction of an effective, peroxidase-free ratiometric fluorescence framework for the detection of H2O2 and glucose, which has also been used in the successful detection of glucose in human serum. Results from this study not only demonstrate a new peroxidase mimic but also provide a novel ratiometric fluorescence platform for the detection of H2O2 and metabolites involving reactions of H2O2 generation in the absence of horseradish peroxidase.