Charge separation and photosensitized damage in DNA mediated by naphthalimide, naphthaldiimide, and anthraquinone.

J Phys Chem B

The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.

Published: August 2010

Charge-separation and charge-recombination dynamics and oxidative DNA degradation were investigated for DNA modified with a photosensitizer (Sens) naphthalimide (NI), naphthaldiimide (ND), or anthraquinone (AQ). In all three Sens-modified DNA systems, the formation of long-lived charge-separated states was observed in which the lifetime increased with increasing numbers of A-T base pairs between Sens and the neighboring G-C base pair. The lifetime of the charge-separated state correlated well with the DNA damage yield, indicating that the charge-separated state provides time for the irreversible DNA oxidative damage to occur. The quantum yield of DNA damage was the lowest for ND-modified DNA due to the slow reaction of ND radical anion with molecular oxygen; the process needed to preclude charge recombination. The AQ-modified DNA resulted in the highest charge separation and subsequent DNA damage yield, which would be partly explained by the formation of the spin-forbidden triplet radical ion pairs during charge separation.

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http://dx.doi.org/10.1021/jp102483kDOI Listing

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