Achieving efficient photodynamic therapy under both normoxia and hypoxia using cyclometalated Ru(ii) photosensitizer through type I photochemical process

• Published in: Chemical science (Cambridge) Vol. 9; no. 2; pp. 502 - 512
• Main Authors: Lv, Zhuang, Wei, Huanjie, Li, Qing, Su, Xianlong, Liu, Shujuan, Zhang, Kenneth Yin, Lv, Wen, Zhao, Qiang, Li, Xianghong, Huang, Wei
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 2018
• Subjects: Anticancer properties; Charge transfer; Coumarin; Hydroxyl radicals; Hypoxia; Oxidation; Photodynamic therapy; Singlet oxygen; Substrates
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c7sc03765a

Photodynamic therapy (PDT) through the generation of singlet oxygen utilizing photosensitizers (PSs) is significantly limited under hypoxic conditions in solid tumors. So it is meaningful to develop effective PSs which can maintain excellent therapeutic effects under hypoxia. Here we reported a coumarin-modified cyclometalated Ru(ii) photosensitizer (
), which exhibits lower oxidation potential and stronger absorption in the visible region than the coumarin-free counterpart. The evaluation of the PDT effect was performed under both normoxia and hypoxia. The results showed that
has a better therapeutic effect than the coumarin-free counterpart in
experiments. Especially under hypoxia,
still retained an excellent PDT effect, which can be attributed to the direct charge transfer between the excited PS and an adjacent substrate through a type I photochemical process, forming highly-oxidative hydroxyl radicals to damage tumor cells. The anti-tumor activity of
was further proven to be effective in tumor-bearing mice, and tumor growth was inhibited remarkably under PDT treatment.