title: Specific local induction of DNA strand breaks by infrared multi-photon absorption.
abstract: Highly confined DNA damage by femtosecond laser irradiation currently arises as a powerful tool to understand DNA repair in live cells as a function of space and time. However, the specificity with respect to damage type is limited. Here, we present an irradiation procedure based on a widely tunable Er/Yb : fiber femtosecond laser source that favors the formation of DNA strand breaks over that of UV photoproducts by more than one order of magnitude. We explain this selectivity with the different power dependence of the reactions generating strand breaks, mainly involving reactive radical intermediates, and the direct photochemical process leading to UV-photoproducts. Thus, localized multi-photon excitation with a wavelength longer than 1 microm allows for the selective production of DNA strand breaks at sub-micrometer spatial resolution in the absence of photosensitizers.
authors.affiliation: Department of Physics, University of Konstanz, D-78457 Konstanz, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Träutlein
authors.forename: M
authors.initials: M
authors.lastname: Deibler
authors.forename: A
authors.initials: A
authors.lastname: Leitenstorfer
authors.forename: E
authors.initials: E
authors.lastname: Ferrando-May
mesh_terms: D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007834:Lasers; D018613:Microscopy, Confocal; D017785:Photons; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D004268:DNA-Binding Proteins; D017382:Reactive Oxygen Species; D000076105:X-ray Repair Cross Complementing Protein 1