title: Direct electron irradiation of DNA in a fully aqueous environment. Damage determination in combination with Monte Carlo simulations.
abstract: 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 Si3N4membrane. 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 D1/2= 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.
authors.affiliation: Free University Berlin, Department of Physics, D-14195 Berlin, Germany. hahn@physik.fu-berlin.de and Bundesanstalt für Materialforschung und Prüfung, D-12205 Berlin, Germany. tihomir.solomun@bam.de.
authors.forename: Marc Benjamin
authors.identifier: http://orcid.org/0000-0002-5050-7083
authors.initials: MB
authors.lastname: Hahn
authors.affiliation: Bundesanstalt für Materialforschung und Prüfung, D-12205 Berlin, Germany. tihomir.solomun@bam.de and University of Potsdam, Institute of Biochemistry and Biology, D-14476 Potsdam, Germany.
authors.forename: Susann
authors.initials: S
authors.lastname: Meyer
authors.affiliation: Bundesanstalt für Materialforschung und Prüfung, D-12205 Berlin, Germany. tihomir.solomun@bam.de.
authors.forename: Maria-Astrid
authors.initials: MA
authors.lastname: Schröter
authors.affiliation: Fraunhofer-Institut für Zelltherapie und Immunologie, Institutsteil Bioanalytik und Bioprozesse, D-14476 Potsdam, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Seitz
authors.affiliation: Bundesanstalt für Materialforschung und Prüfung, D-12205 Berlin, Germany. tihomir.solomun@bam.de.
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Kunte
authors.affiliation: Bundesanstalt für Materialforschung und Prüfung, D-12205 Berlin, Germany. tihomir.solomun@bam.de.
authors.forename: Tihomir
authors.initials: T
authors.lastname: Solomun
authors.affiliation: Bundesanstalt für Materialforschung und Prüfung, D-12205 Berlin, Germany. tihomir.solomun@bam.de and Technical University Berlin, D-10587 Berlin, Germany.
authors.forename: Heinz
authors.identifier: http://orcid.org/0000-0002-8091-4077
authors.initials: H
authors.lastname: Sturm
mesh_terms: D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D004583:Electrons; D009010:Monte Carlo Method; D010957:Plasmids / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D014867:Water / Q000737:chemistry*
chemical_list: D017655:Silicon Compounds; D012996:Solutions; D014867:Water; D004247:DNA; C032734:silicon nitride