Electron-induced damage of DNA and its components: Experiments and theoretical models

It is now over ten years since the seminal experiments of Leon Sanche's group in Sherbrooke have compellingly shown that subexcitation electrons interacting with DNA coulc cause the occurrence of specific resonant processes which in turn would eventually lead to either single or double strand breaks in DNA materials, to the damaging of its molecular components and possibly to biological apoptosis. Since then a great deal of activity has been spurred by that initial work with experiments and computations being carried out in several laboratories around the world. Hence, several components of the DNA molecular structure and make-up, i.e. from the purinic and pyrimidinic bases to the sugar and phosphate fragments, have been analysed in detail in the gas phase, on thin-film deposits on noble metals, and in some form of condensed phase, in interaction with low energy electrons. Likewise, several theoretical and computational approaches have been directed at the study of the molecular processes deemed to be crucially involved in the various steps of the energy deposition by the impinging electron onto the molecular networks. The aim of the present review is therefore to put together, after these ten years of intense activity, the major findings which have been consolidated from the broad variety of existing experiments and, at the same time, the main computational approaches which describe the extent of molecular damage following the initial electron attachment process. The present field, in fact, is becoming mature enough to profitably stand an overall evaluation of its experimental and theoretical/computational results and to further construct, from such a review, a starting point for the assessment of its future directions. After a detailed analysis of the experimental data, in the gas phase and in other phases, we shall therefore report the main computational tools and theoretical concepts employed today for the interpretation of the measurements at the molecular level. An overall analysis of the subject will be attempted in the last Section of this review. (C) 2011 Elsevier B.V. All rights reserved.