title: Radiation Damage to DNA: The Indirect Effect of Low Energy Electrons.
abstract: We report the effect of DNA hydration level on damage yields induced by soft X-rays and photo-emitted low energy electrons (LEEs) in thin films of plasmid DNA irradiated in N2at atmospheric pressure under different humidity levels. Contrary to a dilute solution of DNA, the number of H2O molecules per nucleotide (Γ) in these films can be varied from Γ=2.5 to ~33, where Γ≤20 corresponds to layers of hydration and Γ=33 to an additional bulk-like water layer. Our results indicate that DNA damage induced by LEEs does not increase significantly until the second hydration shell is formed. However, this damage increases dramatically as DNA coverage approaches bulk-like hydration conditions. A number of phenomena are invoked to account for these behaviors including: dissociative electron transfer from water-interface electron traps to DNA bases, quenching of dissociative electron attachment to DNA and quenching of dissociative electronically excited states of H2O in contact with DNA.
authors: Groupe en Sciences des Radiations, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors: Elahe
authors: E
authors: Alizadeh
authors: Instituto de Física Fundumental, Consejo Suporior de Investigaciones Científicas, Madrid, Spain.
authors: Ana G
authors: AG
authors: Sanz
authors: Instituto de Física Fundumental, Consejo Suporior de Investigaciones Científicas, Madrid, Spain.
authors: Gustavo
authors: G
authors: García
authors: Groupe en Sciences des Radiations, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors: Léon
authors: L
authors: Sanche
keywords: DNA damage; humidity level; interface electron; solvation; strand breaks