Highly efficient near-infrared organic dots based on novel AEE fluorogen for specific cancer cell imaging

Near-infrared emissive organic dots with a high fluorescence quantum efficiency (AEE dots) are prepared by using an amphiphilic polymer poly(styrene-co-maleic anhydride) (PSMA) as the co-encapsulation matrix and a novel small molecule fluorogen (DPPBPA) with high near-infrared emission as the core. The PSMA dots show small particle size of about 20 nm, a large Stokes shift of 304 nm and really high fluorescence quantum efficiency of 20%. The streptavidin-dots are obtained by conjugating streptavidin to carboxyl groups on the surface of PSMA dots. These streptavidin-dots can effectively and specifically label the target cell without any nonspecific binding, such as MCF-7 cells. Together with the negligible cytotoxicity, the near-infrared emissive AEE dots are promising red fluorescent probes for future bioimaging applications.