Golgi-targeting red-emissive carbon dots: synthesis, properties and bioimaging

Golgi-targeting carbon dots have garnered significant attention in the field of subcellular organelle imaging owing to their exceptional photoluminescence properties, specific Golgi-targeting abilities, and favorable biocompatibility. Currently reported Golgi-targeting carbon dots primarily exhibit emission wavelengths in the blue and orange spectral regions, which suffer from reduced imaging accuracy because of interference from endogenous tissue autofluorescence and limited tissue penetration. To overcome these disadvantages, red-emissive Golgi-targeting carbon dots (RGCDs) were synthesized using a solvothermal method, with Nile blue, a fluorescent dye known for its large conjugated structure, as the carbon source, and benzene sulfonamide, a known Golgi-targeting ligand, as the targeting moiety. Results demonstrate that RGCDs exhibit superior optical properties, with an emission wavelength centered at 645 nm. Moreover, RGCDs exhibit low cytotoxicity, with rabbit hepatocarcinoma cell viability remaining above 80 % at a concentration of 400 μg/mL. Furthermore, co-localization imaging with a commercial Golgi-targeting dye yielded a high Pearson correlation coefficient of 0.87, indicating that RGCDs possess both long-wavelength emission and specific Golgi targeting capabilities. Additionally, AutoDock simulation analysis confirmed that the sulfonamide groups on the surface of the RGCDs bind to cyclooxygenase-2, a known Golgi-associated protein, enhancing the imaging capabilities of RGCDs.