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Phototoxicity of cyclometallated Ir(III) complexes bearing a thio-bis-benzimidazole ligand, and its monodentate analogue, as potential PDT photosensitisers in cancer cell killing.

Marta Martínez-AlonsoCallum G JonesJames D ShippDimitri ChekulaevHelen E BryantJulia A Weinstein
Published in: Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry (2024)
Two novel cyclometallated iridium(III) complexes have been prepared with one bidentate or two monodentate imidazole-based ligands, 1 and 2, respectively. The complexes showed intense emission with long lifetimes of the excited state. Femtosecond transient absorption experiments established the nature of the lowest excited state as 3 IL state. Singlet oxygen generation with good yields (40% for 1 and 82% for 2) was established by detecting 1 O 2 directly, through its emission at 1270 nm. Photostability studies were also performed to assess the viability of the complexes as photosensitizers (PS) for photodynamic therapy (PDT). Complex 1 was selected as a good candidate to investigate light-activated killing of cells, whilst complex 2 was found to be toxic in the dark and unstable under light. Complex 1 demonstrated high phototoxicity indexes (PI) in the visible region, PI > 250 after irradiation at 405 nm and PI > 150 at 455 nm, in EJ bladder cancer cells.
Keyphrases
  • photodynamic therapy
  • fluorescence imaging
  • induced apoptosis
  • molecular docking
  • radiation therapy
  • signaling pathway
  • human health
  • case control
  • quantum dots
  • pi k akt