A Family of Highly Efficient Ru(II) Photosensitizers with Enhanced DNA Intercalation

Transition metal photosensitizers are very promising for photobiological and photomedicinal applications, as they possess tunable and rationally altered photophysical, photochemical, and photobiological properties. In our... [ view full abstract ]

Transition metal photosensitizers are very promising for photobiological and photomedicinal applications, as they possess tunable and rationally altered photophysical, photochemical, and photobiological properties.

In our present study, a family of tailor-designed Ru(II) based photosensitizers was synthesized and characterized. This family of photosensitizers, bearing a new bipyridine-type ligand of extended conjugation and an attached anthracene moiety, exhibit, upon light activation, enhanced singlet oxygen generation ability even at excitation wavelengths above 600 nm. The complexes obtained carry either PF₆^- or Cl^- counterions, which determine their hydrophobic or hydrophilic character and, therefore, dictate their solubility in biologically-related media.

All photosensitizers exhibit high efficiency in generating cytotoxic singlet oxygen (ΦΔ -0,8). Additionally, the interaction of these compounds with double-stranded DNA was studied fluoro- and photo-spectroscopically and their bonding 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[1].

REFERENCES

[1] Eleftherios K. Pefkianakis, Theodossis A. Theodossiou, Dimitra K. Toubanaki, Evdokia Karagouni, Polycarpos Falaras, Kyriakos Papadopoulos and Georgios C. Vougioukalakis, Photochemistry and Photobiology, 91, 1191–1202, (2015).