N, S co-doped carbon dots for temperature probe and the detection of tetracycline based on the inner filter effect

Nitrogen and sulfur co-doped carbon dots (N, S co-doped CDs) were prepared from glutathione with a hydrothermal method and developed for temperature probe as well as fluorescent sensor of tetracycline. The as-prepared N, S co-doped CDs exhibited good optical properties, stability, water solubility and high fluorescence quantum yield(17.5%). The fluorescence intensity of the N, S co-doped CDs varied with temperature in the range of 10–70 °C. Moreover, based on the inner filter effect (IFE), the nanoparticle-based sensor displayed a wide linear range of 0.1–65 μM (R 2 = 0.9916) and provided an exciting detection limit of 0.04 μM (signal-to-noise ratio of 3) for quantifying tetracycline. More strikingly, the N, S co-doped CDs sensing system could commendably resist the interference from potential foreign substances, and achieved satisfactory recoveries, which indicated the excellent selectivity and sufficient accuracy of the sensor for real milk samples analyses. As a simple and effective optical nanosensor, the proposed N, S co-doped CDs hold admirable promise to broaden the applications in food analysis and others fields.