title: Comparison of free radicals formation induced by cold atmospheric plasma, ultrasound, and ionizing radiation.
abstract: Plasma medicine is increasingly recognized interdisciplinary field combining engineering, physics, biochemistry and life sciences. Plasma is classified into two categories based on the temperature applied, namely "thermal" and "non-thermal" (i.e., cold atmospheric plasma). Non-thermal or cold atmospheric plasma (CAP) is produced by applying high voltage electric field at low pressures and power. The chemical effects of cold atmospheric plasma in aqueous solution are attributed to high voltage discharge and gas flow, which is transported rapidly on the liquid surface. The argon-cold atmospheric plasma (Ar-CAP) induces efficient reactive oxygen species (ROS) in aqueous solutions without thermal decomposition. Their formation has been confirmed by electron paramagnetic resonance (EPR) spin trapping, which is reviewed here. The similarities and differences between the plasma chemistry, sonochemistry, and radiation chemistry are explained. Further, the evidence for free radical formation in the liquid phase and their role in the biological effects induced by cold atmospheric plasma, ultrasound and ionizing radiation are discussed.
authors.affiliation: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan. Electronic address: rehman.mu84@yahoo.com.
authors.forename: Mati Ur
authors.initials: MU
authors.lastname: Rehman
authors.affiliation: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan.
authors.forename: Paras
authors.initials: P
authors.lastname: Jawaid
authors.affiliation: Tateyama Machine Co., Ltd., Business Promotion Department, 30 Shimonoban, Toyama, 930-1305, Japan.
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Uchiyama
authors.affiliation: Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan. Electronic address: kondot@med.u-toyama.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
mesh_terms: D001274:Atmospheric Pressure; D003080:Cold Temperature; D004560:Electricity; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D006371:Helium / Q000737:chemistry; D058626:Plasma Gases / Q000737:chemistry*; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000737:chemistry; D012996:Solutions; D014465:Ultrasonics
chemical_list: D005609:Free Radicals; D058626:Plasma Gases; D017382:Reactive Oxygen Species; D012996:Solutions; D006371:Helium
keywords: Cell killing; Cold atmospheric plasma; EPR spin trapping; Free radicals; Ionizing radiation; Platinum nanoparticles; Reactive oxygen species; Ultrasound