Rational Design of Carbon Dots Featuring High Spectral Overlap with Analyte for Effective Detection of Metronidazole via Inner Filter Effect

The development of fluorescent probe with high spectral overlap with analyte is favorable for the sensing applications via inner filter effect, which requires facile tuning of their structure and photophysical properties. Herein, the rational design of blue emissive carbon dots (B-CDs) is reported for effective detection of metronidazole (MNZ) in both deionized water and real water samples. The design strategy is based on the elaborate choice of precursors that allows precise control over the nitrogen-doping degree and graphitization content of B-CDs. As a result, the as-prepared B-CDs exhibit a specific and quick fluorescence quenching response to MNZ via the IFE mechanism because of their good spectral overlap in absorbance. This approach shows a broad linear range (0.5–160 µm), low detection limit (0.1 µm), and moderate selectivity, suggesting its promise for practical applications in environmental sensing.