Imidazole–carbazole conjugate for two-photon-excited photodynamic therapy and fluorescence bioimaging

A heavy-atom-free photosensitizer (CI) based on an imidazole-carbazole conjugate exhibited strong fluorescence emission and ROS generation via both type I and II mechanisms. In particular, CI showed efficient photodynamic therapy and fluorescence bioimaging under two-photon (TP) excitation (740 nm) toward HeLa cells with negligible dark toxicity.