Preparation of Nitrogen and Boron Codoped Carbon Quantum Dots and Their Application in Long‐Term Real‐Time Tracking and Imaging of Living Cells

Using mung beans as a biomass carbon source, nitrogen and boron codoped carbon quantum dots (N,B‐CQDs) are synthesized via a one‐step solvothermal method. The structure, optical properties, and biocompatibility of N,B‐CQDs are systematically investigated. Characterization results reveal that N,B‐CQDs exhibited uniform particle size distribution (≈3 nm), abundant surface functional groups, and excellent fluorescence properties, with a maximum emission wavelength of 460 nm and excitation wavelength‐dependent behavior. Stability tests demonstrate that N,B‐CQDs maintained high fluorescence intensity (>80%) under light exposure, physiological‐salt conditions, and different pH levels. Biotoxicity experiments confirm that even at high concentrations (500 μg mL −1 ), the viability of MCF‐7 cells remained above 93%, indicating excellent biocompatibility. Furthermore, live‐cell imaging studies show that N,B‐CQDs could stably track cells in real‐time over extended periods, with fluorescence signals transmitted to daughter cells for more than six generations, and their antiphotobleaching performance is significantly superior to that of the traditional dye DAPI. The experimental results demonstrate that N,B‐CQDs can serve as an ideal noninvasive fluorescent probe for long‐term real‐time tracking and imaging of living cells, with broad application prospects.