Synthesis and Spectroscopic Study of a Homogenous Bimetallic Os(II) Complex as a New Gastric Cancer Photosensitizer.

A homogenous dinuclear Os(II) complex bisOs was synthesized and fully characterized. The electrochemical cyclic voltammetry study, and density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed to investigate the electronic property. bisOs showed an obvious interaction with lipase and BSA, and can generate singlet oxygen under blue and red LED light irradiation, with a singlet oxygen quantum yield (Φ) of 0.36 in comparison to that of [Ru(bpy)]Cl in acetonitrile. bisOs exhibited moderate to great photocytotoxicity against HGC-27 human gastric cancer cells under blue LED light irradiation, giving the IC value as low as 1.83 μM (PI value is 9.7), while was almost non-cytotoxic in the dark. The cellular singlet oxygen detection in HGC-27 cancer cells exhibited a concentration-dependent manner, and cell uptake of bisOs in A549 cells was as high as 120 ng/10 cells, subcellular colocalization study indicated that bisOs was not accumulated in nucleus, and less likely to target mitochondria. This work provides a new example of dinuclear osmium complex as potential photosensitizer candidate for gastric treatment.