Damage Induced to DNA by Low-Energy (0-30 eV) Electrons under Vacuum and Atmospheric Conditions

In this study, we show that it is possible to obtain data on DNA damage induced by low-energy (0-30 eV) electrons under atmospheric conditions. Five monolayer lms of plasmid DNA (3197 base pairs) deposited on glass and gold substrates am irradiated with 1.5 keV -rays in ultrahigh vacuum and under atmospheric conditions. The total damage is analyzed by agarose gel electrophoresis. The damage produced on the glass substrate is attributed to energy absorption from -rays, whereas that produced on the gold substrate arises front energy absorption from both the -ray beam and secondary electrons emitted from the gold surface. By analysis of the energy of these secondary electrons, 96 am found to have energies below 30 eV with a distribution peaking at 1.4 eV. ne differences in damage yields recorded with the gold and glass substrates is therefore essentially attributed to the interaction of low-energy electrons with DNA under vacuum and hydrated conditions. From these results, the G values for low-energy electrons are determined to be four and six strand breaks per 100 eV, respectively.