Inactivation pathways of reactive species generated by low temperature atmospheric pressure plasma

Summary form only given. Non thermal atmospheric gas plasmas have been exploited in biology, medicine, dentistry, and material science as a novel technology for health care. The unique enhanced helium gas-phase chemistry of the plasma plume is obtained when the electrons undergo collisions with the background gas and facilitate the formation of radical and metastable states. As a result, the plasma does not cause any thermal damage, since the heavy species such as the ions and neutrals remain within the biologically tolerant temperature regime [Laroussi, M., 2009]. The production of different reactive species such as metastable helium atoms help produce short-lived and long-lived reactive species (O, O₂, O₂^-, O₃, OH, NO, and NO₂) [Laroussi, M., et al., 2005] when air molecules mix with the plume. The plasma pencil utilizes high voltage pulses to generate low temperature atmospheric pressure plasma which has been shown to effectively kill bacteria on innate surfaces, in different media and under different growth conditions [Laroussi, M., et al., 2011]. However, the significant details involved in differentiating the specific reactive species that cause this response still remain elusive. In this paper, bacterial killing as a direct result of reactive species generated by the plasma pencil has been investigated by combining electrical and optical diagnostic techniques with bacterial killing assays.