Cyclooxygenase-2-targeting fluorescent carbon dots for the selective imaging of Golgi apparatus

Golgi apparatus is an important organelle responsible for transporting proteins in cells. Accurate monitoring of Golgi apparatus status by targeting fluorescence imaging technology is of great significance for visualization of Golgi apparatus' physiological status. Cyclooxygenase-2 (COX-2) is a protease on the Golgi apparatus surface of cells. By means of hydrogen bonding between COX-2 and sulfonamide groups, orange-emitting Golgi apparatus-targeting carbon dots (GTCDs) were developed for the efficient imaging monitoring of Golgi apparatus. GTCDs were synthesized from p-phenylenediamine and benzene sulfonamide by one-step solvothermal methods. GTCDs had uniform size (∼3.36 nm), graphitized structure, maximum emission wavelength of 612 nm, low cytotoxicity, 24 h metabolic time, and good photostability. In addition, GTCDs had an excellent Golgi apparatus-targeting effect (average Pearson's co-localization coefficient = 0.92) and ultrafast imaging capability of Golgi apparatus (imaging immediately after the addition of GTCDs). The selective targeting of GTCDs to Golgi apparatus was attributed to the binding of the sulfonamide moiety on the surface of GTCDs to the active pocket site of COX-2 in Golgi apparatus through hydrogen bonds, which led to the localization of GTCDs to Golgi apparatus. It is believed that GTCDs have great potential in the fields of precise organelle imaging and targeting drug delivery as Golgi apparatus-targeting biological fluorescent probes.