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Direct electron irradiation of DNA in a fully aqueous environment. Damage determination in combination with Monte Carlo simulations

: Hahn, M.B.; Meyer, S.; Schröter, M.A.; Seitz, H.; Kunte, H.J.; Solomun, T.; Sturm, H.

Fulltext ()

Physical chemistry, chemical physics : PCCP 19 (2017), No.3, pp.1798-1805
ISSN: 1463-9076
Deutsche Forschungsgemeinschaft DFG
STU 245/4-1, BI 536/3-1
Journal Article, Electronic Publication
Fraunhofer IZI ()

We report on a study in which plasmid DNA in water was irradiated with 30 keV electrons generated by a scanning electron microscope and passed through a 100 nm thick Si3N4 membrane. The corresponding Monte Carlo simulations suggest that the kinetic energy spectrum of the electrons throughout the water is dominated by low energy electrons (<100 eV). The DNA radiation damage, single-strand breaks (SSBs) and double-strand breaks (DSBs), was determined by gel electrophoresis. The median lethal dose of D-1/2 = 1.7 +/- 0.3 Gy was found to be much smaller as compared to partially or fully hydrated DNA irradiated under vacuum conditions. The ratio of the DSBs to SSBs was found to be 1 : 12 as compared to 1 : 88 found for hydrated DNA. Our method enables quantitative measurements of radiation damage to biomolecules (DNA, proteins) in solutions under varying conditions (pH, salinity, co-solutes) for an electron energy range which is difficult to probe by standard methods.