Carbon quantum dots prepared by pyrolysis: Investigation of the luminescence mechanism and application as fluorescent probes

In this work, the effect of reaction conditions on the preparation of CQDs by pyrolysis was studied. More specifically, CQDs-1 with single emission peak of blue fluorescence and CQDs-2 with double emission peak of yellow fluorescence were prepared by pyrolysis methods in a closed and open environment, respectively. The mechanism of the difference in optical properties of the two types of CQDs had been systematically studied. The results showed that the difference in the degree of graphitization and surface state was the main reason for the difference in the optical properties of the two types of CQDs. The CQDs-2 with dual emission characteristics was used for high sensitivity and high selectivity detection of cephalosporin antibiotics based on the inner-filter effect (IFE). The limit of detection (LOD) was 0.87–2.78 μM, with a good recovery rate (99.4–102%) in the milk spike recovery test. Additionally, the cytotoxicity and cell imaging showed that CQDs-1 and CQDs-2 have potential applications in biological systems.