A Family of Potent Ru(II) Photosensitizers with Enhanced DNA Intercalation: Bimodal Photokillers

摘要

A new family of Ru(II)-based photosensitizers was synthesized and systematically characterized. The ligands employed to coordinate the ruthenium metal center were the commercially available 2,2-bipyridine and a pyridine-quinoline hybrid bearing an anthracene moiety. The complexes obtained carry either PF6(-) or Cl- counterions. These counterions determine the complexes' hydrophobic or hydrophilic character, respectively, therefore dictating their solubility in biologically related media. All photosensitizers exhibit characteristic, relatively strong and wide UV-Vis absorption spectral profiles. Their high efficiency in generating cytotoxic singlet oxygen was established (up to phi similar to 0.8). Moreover, the interaction of these photosensitizers with double-stranded DNA was studied fluoro- and photospectroscopically and their binding affinities were found to be of the order of 3x10(7)M(-1). All complexes are photocytotoxic to DU145 human prostate cancer cells. The highest light-induced toxicity was conferred by the photosensitizers bearing Cl- counterions, probably due to the looser ionic chaperoning of Cl-, in comparison to PF6(-), leading to higher cell internalization.