Photoactivated Lysosomal Escape of a Monofunctional Pt^II Complex Pt-BDPA for Nucleus Access

A photosensitizing monofunctional Pt complex, Pt-BDPA, was prepared with a BODIPY chromophore. Apart from its DNA binding ability, this complex displays emission at ca. 578 nm and a singlet oxygen quantum yield of 0.133. Confocal imaging revealed that this complex was sequestered in lysosomes via endocytosis in the dark, preventing its access to the nucleus. Profiting from its photoinduced ROS generation ability, this complex undergoes lysosomal escape to access the nucleus upon photoirradiation. The photoinduced ROS still cause a drop in intracellular GSH, favoring the stability of Pt-BDPA and contributing to its nuclear DNA accessibility. This complex displayed distinct cytotoxicity to all tested tumor cell lines upon photoirradiation, and the IC₅₀ values were ca. 3-6 μm, which are distinctly lower than those found with only dark incubation (IC₅₀ >50 μm). These results are consistent with photoactivated lysosomal escape of this photosensitizing Pt complex to access the nucleus.