EPR-Spin Trapping and Flow Cytometric Studies of Free Radicals Generated Using Cold Atmospheric Argon Plasma and X-Ray Irradiation in Aqueous Solutions and Intracellular Milieu

• DOI: 10.1371/journal.pone.0136956
• Publication Date: 2015-08-28T14:32:54Z
• Authors: Hidefumi Uchiyama; Qing-Li Zhao; Mariame Ali Hassan; Gabor Andocs; Nobuyuki Nojima; Keigo Takeda; Kenji Ishikawa; Masaru Hori; Takashi Kondo
• Keywords: Spin trapping

Electron paramagnetic resonance (EPR)-spin trapping and flow cytometry were used to identify free radicals generated using argon-cold atmospheric plasma (Ar-CAP) in aqueous solutions intracellularly comparison with those by X-irradiation. Ar-CAP was a high-voltage power supply unit low-frequency excitation. The characteristics of estimated vacuum UV absorption emission spectra measurements. Hydroxyl (·OH) hydrogen (H) atoms identified the spin traps 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO), phenyl N-t-butylnitrone (PBN). occurrence Ar-CAP-induced pyrolysis evaluated trap 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) DNA constituents, sodium acetate, L-alanine. Human lymphoma U937 cells study intracellular oxidative stress five fluorescent probes different affinities number reactive species. analysis quantification EPR revealed formation enormous amounts ·OH compared that Very small H detected whereas nitric oxide not found. depended on type rare gas yield correlated inversely ionization energy order krypton > argon = neon helium. No exposed Ar-CAP. Intracellularly, ·OH, H2O2, which is recombination product OCl- most likely formed oxygen species after exposure there no practical evidence for NO very superoxides formed. Despite superiority forming radicals, X-rays proved more lethal. mechanism radical an milieu discussed.