Green synthesis of graphitic carbon nitride nanosheet (g-C3N4) and using it as a label-free fluorosensor for detection of metronidazole via quenching of the fluorescence.

In this research, g-C3N4nanosheets were facilely fabricated by thermal polymerization and then exfoliated into ultrathin nanosheets through ultrasonication in water media. Low-cost C-N nanosheets prepared by melamine possessed a highly π-conjugated structure and fluorescence property. In the present study, the g-C3N4nanosheet was used as a switch-off fluorescence sensor for rapid and sensitive sensing of metronidazole in biological fluids. These nanosheets were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The fluorescence of the solution of the g-C3N4nanosheets was quenched effectively by metronidazole through two mechanisms: fluorescence resonance energy transfer and the formation of a donor-acceptor charge-transfer complex between π-electron rich donors. Under optimal conditions, the detection linear range for metronidazole was found to be from 0.01 to 0.10µgml-1, with a limit of detection (LOD) of 0.008µgml-1 which can cover standard range of metronidazole in real samples. Moreover, the proposed method has offered a green, rapid, and sensitive probe for quantitative determination of metronidazole in drug and biological fluids.