A novel “on–off–on” fluorescent probe based on carbon dots for dual-detecting rifampicin and levofloxacin

In this work, carbon dots (CDs) with blue fluorescence emission were synthesized using citric acid and cysteine through simple one-pot hydrothermal method. Under the optimal experimental conditions, the fluorescence intensity of the CDs could be quenched by rifampicin (RIF), with a good linear relationship ( R 2 = 0.9925), and the limit of detection (LOD) was determined to be 0.687 μg mL −1 . Furthermore, the quenched fluorescence of CDs-RIF system could be restored by levofloxacin (LEV), the fluorescence intensity of CDs-RIF was continuously enhanced with the increase of the LEV concentration, which also showed a good linear relationship ( R 2 = 0.9929), and the LOD was 0.965 μg mL −1 . Based on this discovery, a low-cost fluorescent probe with dual-detection performance was constructed and applied for the rapid and accurate detection of RIF and LEV residues in actual samples.