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Article Dans Une Revue Journal of Physical Chemistry B Année : 2017

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

Résumé

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 × 1011 cm–2 at 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 rmax values 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.
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Dates et versions

hal-01559863 , version 1 (11-07-2017)

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Citer

Mounir Souici, Talat T. Khalil, Dominique Muller, Quentin Raffy, Rémi Barillon, et al.. Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies. Journal of Physical Chemistry B, 2017, 121 (3), pp.497 - 507. ⟨10.1021/acs.jpcb.6b11060⟩. ⟨hal-01559863⟩
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