Generation of DNA photolesions by two-photon absorption of a frequency-doubled Ti:sapphire laser
The formation of spatially localized regions of DNA damage by multiphoton absorption of light is an attractive tool for investigating DNA repair. Although this method has been applied in cells, little information is available about the formation of lesions by multiphoton absorption in the absence of...
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Published in | Journal of photochemistry and photobiology. B, Biology Vol. 102; no. 2; pp. 161 - 168 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Switzerland
Elsevier B.V
07.02.2011
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Subjects | |
Online Access | Get full text |
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Summary: | The formation of spatially localized regions of DNA damage by multiphoton absorption of light is an attractive tool for investigating DNA repair. Although this method has been applied in cells, little information is available about the formation of lesions by multiphoton absorption in the absence of exogenous or endogenous sensitizing agents. Therefore, we have investigated DNA damage induced
in vitro by direct two-photon absorption of frequency-doubled femtosecond pulses from a Ti:sapphire laser. We first developed a quantitative polymerase chain reaction assay to measure DNA damage, and determined that the quantum yield of lesions formed by one-photon absorption of 254
nm light is 7.86
×
10
−4. We then measured the yield of lesions resulting from exposure to the visible femtosecond laser pulses, which exhibited a quadratic intensity dependence. The two-photon absorption cross section of DNA has a value (per nucleotide) of 2.6 GM at 425
nm, 2.4 GM at 450
nm, and 1.9 GM at 475
nm. A comparison of these
in vitro results to several
in vivo studies of multiphoton photodamage indicates that the onset of DNA damage occurs at lower intensities
in vivo; we suggest possible explanations for this discrepancy. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 1011-1344 1873-2682 |
DOI: | 10.1016/j.jphotobiol.2010.11.004 |