A lysosomal targeted NIR photosensitizer for photodynamic therapy and two-photon fluorescence imaging

The design and synthesis of near-infrared (NIR) emissive fluorophores for the imaging of organelles and photodynamic therapy have received enormous attention. Hence, the development of NIR emissive fluorophores for high-fidelity lysosome targeting, two-photon fluorescence imaging, and the inducing of photo-triggered cancer-cell apoptosis is highly desirable. In this study, a novel lysosome-targeting two-photon fluorescent photosensitizer (TTRh-CN) is prepared and comprehensively investigated. TTRh-CN demonstrates near-infrared (NIR) emission, good biocompatibility, and superior photostability, and it can act as a two-photon fluorescent agent for the clear visualization of living cells and the vascular system within tissue, with deep-tissue penetration abilities. Furthermore, TTRh-CN can efficiently produce ROS in conjunction with lysosomes in situ upon light irradiation, which can damage lysosomes, up-regulate LC3 and Beclin1, increase BAX release, and induce cell apoptosis. The efficacy of TTRh-CN as a photosensitizer is explored in vivo. All these results confirm that TTRh-CN can serve as a potential platform for the two-photon fluorescence imaging of cells/tissue and for organelle-specific photodynamic therapy.