Photosensitizers’ dual functions in photodynamic cancer therapy and ClO- detection
We designed and synthesized the thionated NpImidazole derivatives BS and NS, new heavy-atom-free photosensitizers, which efficiently generates a triplet excited state with high singlet oxygen quantum yield. The introduction of C=S bond to NpImidazole core is essential for increasing spin-orbit coupling (SOC). The fluorescence emission of BS and NS were quenched at standard ambient temperature, accompanying with the increase of ISC process from the singlet states to triplet excited states via thionation. BS and NS showed negligible dark cytotoxicity against HeLa cells in working concentration. In the contrast, BS and NS rapidly induced cell death under blue light irradiation both in normoxia and hypoxia condition. Our current study demonstrates that C=S group can play an important role in type I ROS generation of PSs, which have unprecedented in the previous reports. Finally, the photophysical changes was assigned to the oxidative desulfurization of C=S group of BS and NS to C=O group of the corresponding BO and NO via hypochlorite. The combined results demonstrated the dual function of BS and NS as a fluorescent imaging agent for ClO- and an anti-cancer therapeutic by PDT that showed the potential strategy for “one-for-all” as well as multifunctional agents.
