Two‐Color Two‐Laser DNA Damaging

Abstract

A combination of two‐color pulses allows a high DNA‐damaging efficiency. The first laser pulse is applied to produce Sens.− and DNA.+, and the second laser pulse causes the ejection of an electron from Sens.−, thus making the reaction irreversible. Sens=photosensitizer.

Selective guanine oxidation by UVB-irradiation in telomeric DNA

“…Recently, UVAirradiation in the presence of photosensitizers has been shown to accelerate telomere shortening via DNA damage caused by guanine (G) oxidation, [3][4][5][6] based on electron transfer between G and the photoexcited photosensitizers. [7][8][9][10][11][12][13][14][15] DNA is a principal target of UV-induced cellular damage causing carcinogenesis and photoaging, and it is well known that the most prevalent DNA lesion is the cis-syn cyclobutane thymine dimer induced by UVB irradiation. [16][17][18] However, it is generally accepted that UVirradiation does not induce pyrimidine dimer formation in telomeric DNA.…”

8-Oxo-7,8-dihydro-2′-deoxyguanosine produces a long-lived charge-separated state during the photosensitized one-electron oxidation of DNA resulting in efficient and exclusive degradation

“…The nanosecond transient absorption measurements were performed using the laser flash photolysis technique. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] Briefly, the third-harmonic oscillation (355 nm, FWHM of 4 ns, 6 mJ/ pulse) from a Q-switched Nd:YAG laser (Continuum, Surelight) was used for the excitation light which was expanded to a 1-cm diameter. The light from a xenon flash lamp (Osram, XBO-450) was focused into the sample solution for the transient absorption measurement.…”

Photosensitized one-electron oxidation of DNA

“…Here, we report the first study of nanosecond-laser DNA damage, using a combination of two-color pulses as a promising new strategy to reach a high DNA-damaging efficiency. The first laser pulse was applied for the production of the Sens ؒ− and DNA ؒ+ , and the second laser pulse for the electron ejection from Sens ؒ− [48], making the reaction irreversible [49].…”