Hahn, M.B.M.B.HahnMeyer, S.S.MeyerSchröter, M.A.M.A.SchröterSeitz, H.H.SeitzKunte, H.J.H.J.KunteSolomun, T.T.SolomunSturm, H.H.Sturm2022-03-052022-03-052017https://publica.fraunhofer.de/handle/publica/25172910.1039/c6cp07707bWe 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.en610541620journal article