Photoresponsive Ferrocene- Augmented Iridium Polypyridyl Complex as an Oxidase Mimic for Selective Glutathione Sensing: Implications for Cancer Diagnostics and Therapy.

The enzyme-mimic activity of a well-defined structurally characterized organometallic complex, [Ir(ppy)₂(fcbpy)]PF₆(1; ppy = 2-phenylpyridine; fcbpy = 4-ferrocenyl-2,2'-bipyridine), a bimetallic iridium-polypyridyl complex is investigated under light irradiation for the first time. This complex exhibits an extended excited-state lifetime of 592 ns due to bimetallic synergy, and possess oxidase-mimic activity in the presence of light. Leveraging this light-activated oxidase-mimic activity, a simple colorimetric assay is developed that successfully differentiates cancerous cells from normal cells, based on elevated glutathione (GSH) levels. Moreover, in cell viability studies, treatment with 1.25 mg L-1 of [Ir(ppy)₂(fcbpy)]PF₆ resulted in only 32.25% viability in a cancer cell line (A549) compared to the untreated control, highlighting its potent anticancer potential. Importantly, noncancerous cells (BEAS-2B) maintain ≈72% viability at up to 10 mg L-1 of catalyst concentration, indicating selective cytotoxicity toward cancer cells. This study establishes [Ir(ppy)₂(fcbpy)]PF₆ as a promising candidate for both diagnostic and therapeutic applications in cancer, introducing a novel class of organometallic complexes with significant potential in bioassay development and targeted cancer treatment.