Polypyridyl ruthenium(ii) complexes functionalized with fatty acids for photodynamic therapy and induction of pyroptosis

Abstract

To address the challenges associated with the low cellular uptake efficiency of metal-based anticancer agents and the suboptimal therapeutic efficacy of photodynamic therapy (PDT), a series of polypyridyl ruthenium(II) complexes (Ru–Cn) with tunable carbon chain lengths were rationally designed and synthesized through the incorporation of fatty acid moieties, which confer enhanced lipid solubility and membrane-targeting capabilities. Among these, the octadecanoic acid-modified ruthenium complex (Ru-C18) exhibited superior anticancer activity. Cytotoxicity assays demonstrated that Ru-C18 displayed sub-molar cytotoxic potency under light irradiation. Co-localization studies confirmed its preferential accumulation in lysosomes after cellular internalization. Upon light activation, Ru-C18 efficiently generated singlet oxygen and induced hallmark features of pyroptosis, including plasma membrane blebbing, cellular swelling, and gasdermin-dependent membrane pore formation. Consequently, Ru-C18 significantly suppressed tumor cell proliferation via activation of the pyroptotic pathway. These findings offer new insights into the rational design of highly effective and selectively targeted photodynamic anticancer agents.