A nitrogen-doped carbon dot fluorescent probe for sensitive detection of metronidazole in pharmaceutical samples and evaluation of its cytotoxicity and cell imaging performance

a simple hydrothermal method using glucose and ammonium sulfite as precursors and characterized by TEM, XRD, and XPS. A fluorescent detection system for MTZ was constructed based on MTZ-induced fluorescence quenching of N-CDs, showing a linear range of 1.0-125 µM and a detection limit (LOD) of 0.64 µM. The method was verified by HPLC with a relative deviation of <5% and successfully applied to MTZ tablet detection, yielding spiked recoveries of 99.5-100.4% and RSD < 0.5%. Additionally, MTT assay and laser confocal microscopy demonstrated that N-CDs exhibit low cytotoxicity and excellent cell imaging capability. Collectively, the N-CDs provide a simple and reliable multifunctional platform for trace MTZ detection in pharmaceuticals and potential live cell imaging applications.