Visible light induced antibacterial properties of a Ru(II)–Pt(II) bimetallic complex

Abstract The development of antibiotics with new modes of action and specificity are necessary with the emergence of multidrug resistant Gram-negative bacteria. Antimicrobial photodynamic therapy (aPDT) affords reactive oxygen species, which generally overcomes the conventional bacterial resistance mechanisms, but typical aPDT agents do not strongly associate with Gram-negative bacteria. However, by covalently coupling a Ru-based chromophore with a cis -PtCl 2 bioactive site, covalent interactions with the cell at the Pt moiety provides localization of the singlet oxygen generating chromophore. Reported here is the photoinhibition and photocytotoxicity of Escherichia coli , using the mixed-metal complex [Ru(Ph 2 phen) 2 (dpp)PtCl 2 ] 2+ (Ph 2 phen = 4,7-diphenyl-1,10-phenanthroline and dpp = 2,3-bis(2-pyridyl)pyrazine) in the presence of oxygen and low energy visible light. The Ru(II)–Pt(II) bimetallic complex shows promise as a photoactivated antibacterial agent that interacts with cells in a fundamentally different mode of action than cisplatin.