Ru, Os, Rh mixed-metal complexes are a potential novel class of oxygen independent photosensitizers for photodynamic therapy (PDT)

摘要

Mixed-metal supramolecular complexes coupling Ru and Os light absorber units to a central, reactive Rh site have been designed of the type [{(bpy)_2M(dpp)}_2RhCl_2]~(5+). These complexes possess intense metal-to-ligand charge transfer transitions when excited at 500-700 nm making them good light absorbers. The presence of the Rh site introduces low lying metal-to-metal charge transfer states that are capable of visible light induced photocleavage of DNA via an oxygen independent pathway. We report here a study of the photodynamic action of supramolecular mixed-metal complexes showing that these systems inhibit cell replication after exposure to light while displaying no impact on cell replication in the dark. This photodynamic action has been studied using cultured Vero cells with a pre-incubation with the complexes, rinsing to remove complex from the media, followed by photo-activation and cell growth assay. The photodynamic action of this new series of complexes can be tuned as a function of components of the supramolecular assembly and complexes capable of coupling to targeting proteins and fluorescent reporter groups have been synthesized.