Long-wavelength excitation of carbon dots as the probe for real-time imaging of the living-cell cycle process

Cell-cycle targeting probes are crucial for observing and understanding how different drugs affect the cell stages. Here, we designed and prepared fluorescent F and N co-doped carbon dots (FNCDs) with a long-wavelength excitation, excellent optical stability, high fluorescence quantum yield (57 %), good water-solubility, low toxicity, and anti-photobleaching. The FNCDs have a positively charged surface, which enables easy absorption into DNA and RNA in vitro. For living cells, FNCDs can disperse the 4T1 cell via endocytosis pathways, and label both the nucleolus and chromosome. Due to long-wavelength excitation and excellent anti-photobleaching, we used the FNCDs as probes to directly monitor the cell division of living 4T1 cells, and we obtained the whole progress of cell division for the same cell. The experimental data showed the different chromosome morphologies of living cells in the various stages of cell division. Because of the low cost of raw material and excellent optical stability, FNCDs will hopefully replace dyes as nuclear and chromosome probes. This may open new ways to apply FNCDs in modern biology and cytology.