title: Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies.
abstract: Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90-3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a maximum in the 150-200 keV energy range; as for LET, it peaks at 90 keV. We also show that fragmentation starts to be significant for proton fluences greater than 1 × 1011cm-2at the Bragg-peak energies. Finally, we determine the average proton track radial extension, rmax, corresponding to an occupation probability of 100% DSB in the Bragg-peak region. The rmaxvalues determined are in excellent agreement with the radial extensions of proton tracks determined by simulation approaches in water. When plotted as a function of LET, both SSB and DSB cross sections bend back at high LETs.
authors.affiliation: Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement , 16 Route de Gray, 25030 Besançon Cedex, France.|Laboratoire de Physique des Rayonnements et Applications, Université de Jijel , BP 98, Ouled Aissa, Jijel 18000, Algérie.
authors.forename: Mounir
authors.initials: M
authors.lastname: Souici
authors.affiliation: Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement , 16 Route de Gray, 25030 Besançon Cedex, France.
authors.forename: Talat T
authors.initials: TT
authors.lastname: Khalil
authors.affiliation: Laboratoire ICube, CNRS-Université de Strasbourg , 23 rue du Loess, 67037 Strasbourg, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Muller
authors.affiliation: Institut Pluridisciplinaire Hubert Curien, UMR CNRS 7178 , 23 rue du Loess, BP 28, 67037 Strasbourg Cedex 2, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Raffy
authors.affiliation: Institut Pluridisciplinaire Hubert Curien, UMR CNRS 7178 , 23 rue du Loess, BP 28, 67037 Strasbourg Cedex 2, France.
authors.forename: Rémi
authors.initials: R
authors.lastname: Barillon
authors.affiliation: Laboratoire de Physique des Rayonnements et Applications, Université de Jijel , BP 98, Ouled Aissa, Jijel 18000, Algérie.
authors.forename: Abdelfettah
authors.initials: A
authors.lastname: Belafrites
authors.affiliation: Université de Bordeaux, CNRS/IN2P3, Centre d'Etudes Nucléaires de Bordeaux Gradignan, CENBG , Chemin du Solarium, BP 120, 33175 Gradignan, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Champion
authors.affiliation: Université de Bourgogne Franche-Comté, UMR CNRS 6249 Chrono-Environnement , 16 Route de Gray, 25030 Besançon Cedex, France.
authors.forename: Michel
authors.identifier: 0000-0002-3344-7621
authors.initials: M
authors.lastname: Fromm
mesh_terms: D004247:DNA / Q000737:chemistry*; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D018499:Linear Energy Transfer; D010957:Plasmids; D011091:Polyesters / Q000737:chemistry; D011522:Protons
chemical_list: D011091:Polyesters; D011522:Protons; D004247:DNA