HClO-responsive dinuclear Ru(II) complexes for selective imaging and efficient photo-inactivation of intracellular bacteria

Intracellular bacteria (ICB), cloaked by the protective barriers of host cells, pose a formidable challenge to selective and efficient eradication. The employment of activatable photosensitizers based antibacterial photodynamic therapy (aPDT) holds significant potential for selective imaging and photo-inactivation of ICB while minimizing side effects on normal cells. Drawing inspiration from the elevated hypochlorous acid (HClO) levels in ICB infected phagocytes, herein we firstly designed and synthesized a series of HClO-responsive dinuclear Ru(II) complexes (Ru1-Ru3) to achieve such a goal. Initially, the luminescence, 1O2 generation and aPDT activity of these Ru(II) complexes were suppressed due to the quenching effect of the azo group, but were recovered after reaction with HClO in solutions or within ICB infected phagocytes. The detailed results revealed that Ru1 and Ru3 could not only selectively visualize ICB, but also demonstrated remarkable aPDT activity against ICB, surpassing vancomycin both in vitro and in vivo.