DNA Microviscosity Converts Ruthenium Polypyridyl Complexes to Effective Photosensitizers

A unique radiative decay engineering strategy using DNA microviscosity for the generation of ruthenium polypyridyl complex (RPCs) mediated singlet oxygen for selective damage of DNA and killing cancer cells is reported. This investigation also demonstarte the effect of light-driven RPCs on bacterial growth arrest, through DNA nick, and differential localization in cancer and non-cancer cells. Moreover, upon binding with DNA, RPCs experience high local microviscosity, which causes significant enhancement of the excited state lifetime and thus generates singlet oxygen. The visible-light-triggered singlet-oxygen efficiently produce nick in DNA and inhibits bacterial growth. RPCs also localize inside the nucleus of the cancer cell and in the vicinity of the nuclear membrane of non-cancerous cells, confirmed by live-cell confocal microscopy. The results provide a facile platform for the novel antibiotic intended discovery combined with cancer therapy.