Yeast Cryptococcus Podzolicus derived fluorescent carbon dots for multicolour cellular imaging and high selectivity detection of pollutant

Novel blue fluorescent carbon dots (CDs- CP ) deriving from yeast Cryptococcus podzolicus 5–2 were successfully prepared via a facile and green hydrothermal synthesis method. It exhibited uniform particle size and possessed good excitation-dependent characteristic. The dead bacterial cells were selectively labled by the CDs- CP , but the live ones not, indicating good potential for the live/dead bacterial differentiation. It was found that the prepared CDs- CP showed low biotoxicity and excellent biocompatibility with multicolour fluorescence emission properties, which provided a new insight on the bioimaging application. In addition, the prepared CDs- CP exhibits high selectivity and sensitivity in Ag(I), 2,4-dinitrophenol (2,4-DNP) and 4-nitrophenol (4-NP) detection with excellent linear ranges of 0–15 μM (R 2  = 0.9945), 0–30 μM (R 2  = 0.9959) and 0–37.5 μM (R 2  = 0.9982), respectively. The low detection limits of Ag(I), 2,4-DNP and 4-NP were 113.57 nM, 73.36 nM and 86.47 nM, respectively. It revealed that static quenching mechanism dominated in Ag(I) quenching of the CDs- CP fluorescent, while those of 2,4-DNP and 4-NP were inner filter effect. The fluorescent CDs- CP was successfully applied to determine the Ag(I), 2,4-DNP and 4-NP in real water samples with satisfactory results. Therefore, it is a good candidate for bioimaging application and environmental pollutant detection.