Highly Selective Detection of Metronidazole by Self-Assembly via 0D/2D N–C QDs/g-C3N4 Nanocomposites Through FRET Mechanism

Abstract A 0D/2D (0-dimensional/2-dimensional) nanostructure was designed by self-assembly of N–C QDs and carboxylated g-C 3 N 4 nanosheets and used as a fluorescence resonance energy transfer (FRET) fluorescent sensor. The N–C QDs/g-C 3 N 4 nanosheets were synthesized via the amino group on the N–C QD surface and the –COOH of the carboxylated g-C 3 N 4 nanosheets. The mechanism of detection of metronidazole (MNZ) by N–C QDs/g-C 3 N 4 nanocomposites is based on FRET between negatively charged N–QDs and positively charged carboxylated g-C 3 N 4 nanoparticles. N–C QDs/g-C 3 N 4 nanostructures displayed good responses for the detection of MNZ at normal temperature and pressure. The decrease in the fluorescence intensity showed a good linear relationship to MNZ concentration within 0–2.6 × 10 −5  mol/L, and the detection limit was 0.66 μM. The novel FRET sensor will have a great potential in clinical analysis and biological studies. Graphical Abstract