B, N co-doped carbon quantum dots with strong resistance to light bleaching and their application in lysosome-targeted imaging

The construction of efficient lysosome visualization and tracking probes holds significant research value. Herein, boron-nitrogen co-doping carbon quantum dots (BCQDs) with dual-emission fluorescence and lysosome-targeted imaging functionality were successfully synthesized. The BCQDs exhibited dual-emission fluorescence, with the long-wavelength emission at 580 nm significantly suppressing background biological autofluorescence. BCQDs exhibited excellent fluorescence stability under varying Na⁺ concentrations, pH values, storage times, and temperatures, along with outstanding biocompatibility. The boronic acid groups (-B(OH)₂) on BCQDs form reversible boronate esters with cis-diol groups on lysosomal glycoproteins, which are stabilized under acidic conditions, promoting preferential accumulation and targeted localization in lysosomes. A high colocalization coefficient (0.94) with Lyso-tracker Red (LTR) confirmed the specific lysosomal targeting of BCQDs. BCQDs demonstrated superior photostability to LTR, attributed to the boron-nitrogen co-doping which optimized the electronic structure and enhanced surface stability. Therefore, BCQDs served as outstanding lysosome-targeting probes, enabling long-term and high-resolution imaging.