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Article Dans Une Revue Radiation Physics and Chemistry Année : 2016

Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations

Michel Fromm
Omar Boulanouar
  • Fonction : Auteur

Résumé

In this paper we present in a first part the latest results of our group which are in relation with the study of DNA damages inflicted by low energy electrons (0-20 eV) in ultra-high vacuum as well as in air under atmospheric conditions. A short description of the drop-casting technique we developed to produce thin and nanometre-scaled DNA layers onto graphite sheets is given. We provide the absolute cross-section for loss of supercoiled topology of plasmid DNA complexed with 1,3diaminopropane (Dap) in the vacuum under 10 eV electron impact and suggest a specific pathway for the dissociation of the transient negative ion formed by resonant capture of such a low energy electron (LEE) by the DNA's phosphate group when complexed to Dap. Well-gauged DNA-Dap layers with various nanometre-scaled thicknesses are used to evaluate the effective attenuation length of secondary photo-LEEs in the energy range (0-20 eV). The values of 11-16 nm for DNA kept under atmospheric conditions are in good agreement with the rare literature data available and which are stemming from computer simulations. In a second part, we describe the method we have developed in order to expose liquid samples of plasmid DNA to ultra-soft X-rays (Al Kα line at 1.5 keV) under hydroxyl radical scavenging conditions. We provide an experimentally determined percentage of indirect effects in aqueous medium kept under standard conditions of 94.7 ± 2.1 % indirect effects; in satisfactory agreement with the data published by others (i.e. 97.7%) relative to gamma irradiation of frozen solutions (Tomita et al., 1995).
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Dates et versions

hal-03558190 , version 1 (04-02-2022)

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Michel Fromm, Omar Boulanouar. Low energy electrons and ultra-soft X-rays irradiation of plasmid DNA. Technical innovations. Radiation Physics and Chemistry, 2016, 128, pp.44 - 53. ⟨10.1016/j.radphyschem.2016.05.025⟩. ⟨hal-03558190⟩
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