Chloramines of amino acids as precursors of bactericidal activity in cell culture media DMEM and RPMI treated by RF‐driven He/O2 plasma jet

Antibacterial properties and chemical changes of two culture media, Dulbecco's Modified Eagle Medium (DMEM) and Roswell Park Memorial Institute (RPMI), treated by RF‐driven He/O2 plasma jet, were studied using various chemical diagnostics and assessing Escherichia coli inactivation. The antibacterial effect increased with the plasma treatment time and was stronger in RPMI than in DMEM. Formation of organic mono‐ and dichloramines of amino acids in DMEM/RPMI by hypochlorite produced by the reaction of plasma‐generated O atoms with Cl− ions present in culture media were the major causes of the biocidal activity. This behavior was attributed to the action of tertiary chemical products formed by the decay of organic dichloramines. The thiobarbituric acid assay revealed malondialdehyde formation from glucose oxidation as the major component of the media. Cell culture media have been shown to be effective as disinfectants and antitumor agents after treatment with nonthermal plasma. This study presents antibacterial properties and chemical changes in Dulbecco's Modified Eagle Medium (DMEM) and Roswell Park Memorial Institute (RPMI) media treated by He/O2 plasma jet. Chlorination and formation of organic mono‐ and dichloramines of amino acids in media by hypochlorite produced by the reaction of plasma‐generated O atoms with Cl− ions were the major processes accompanied by the biocidal activity of plasma‐modified media.