A Platinum(II) Complex of Heptamethine Cyanine for Photoenhanced Cytotoxicity and Cellular Imaging in Near‐IR Light

Controlled generation of cytotoxic agents with near‐IR light is a current focus of photoactivated cancer therapy, including that involving cytotoxic platinum species. A heptamethine cyanine scaffolded PtII complex, IR797‐Platin exhibits unprecedented Pt−O bond scission and enhancement in DNA platination in near‐IR light. This complex also displayed significant singlet oxygen quantum yield thereby qualifying as a near‐IR photodynamic therapeutic agent. The complex showed 30–60 fold enhancement of cytotoxicity in near‐IR light in various cancer cell lines. The cellular imaging properties were also leveraged to observe its significant co‐localization in cytoplasmic organelles. This is the first demonstration of a near‐IR light‐initiated therapy involving the cytotoxic effects of both active cisplatin and singlet oxygen. A platinum(II) complex of heptamethine cyanine, IR797‐Platin, showed near‐IR light‐induced Pt−O bond dissociation leading to enhanced DNA platination. IR797‐Platin also showed significant singlet oxygen generation, which resulted in mitochondria‐targeted PDT effects in cancer cells.