Pd nanoparticle-decorated graphitic C3N4 nanosheets with bifunctional peroxidase mimicking and ON-OFF fluorescence enable naked-eye and fluorescent dual-readout sensing of glucose

In this work, we report a novel naked-eye and fluorescent dual-readout glucose sensing platform based on the bifunctional peroxidase mimicking and ON-OFF fluorescence of Pd nanoparticle-decorated graphitic C3N4 nanosheets (PdNPs/g-C3N4). The PdNPs/g-C3N4 hybrid not only exhibited a strong peroxidase-like activity to catalyze colorless o-phenylenediamine (OPD) into its yellow product OPDox in the presence of H2O2, but it also acted as a turn-off fluorescent sensor for the assembly of the generated OPDox on g-C3N4. When coupled with glucose oxidase (GOx), the platform could provide both visual and fluorescent responses for glucose specifically. Under optimal conditions, the platform was able to detect the target at concentrations as low as 50 M and 0.4 M in the linear ranges of 50-2000 M and 1-1000 M with the naked eye and a fluorometer, respectively. The developed platform integrates the equipment-free merit of naked-eye observation with the excellent performance of fluorometric analysis well, providing a new and powerful tool for both rough assessment and accurate detection of glucose in diabetes management and other applications.