Highly purified plasmid DNA both with and without amino acids (glycine and arginine) was irradiated using a cold plasma under ambient conditions. Damage to the plasmid DNA in the form of single- and double-strand breaks was determined by gel electrophoresis. Depending on either the molar ratio of the amino acid: nucleotide mixture or the type of amino acid used, some measure of protection of the DNA can be achieved. (C) 2010 Elsevier B.V. All rights reserved.