As an emerging sterilization technology, cold atmospheric plasma offers a dry, non-thermal, rapid process that is minimally damaging to a majority of substrates. However, the mechanisms by which plasma interacts with living cells are poorly understood and the plasma generation apparatuses are complex and resource-intensive. In this study, the roles of reactive oxygen species (ROS), nitric oxide (NO), and charged particles (ions) produced by surface dielectric barrier discharge (SDBD) plasma on prokaryotic (Listeria monocytogenes (Gram-positive)) and eukaryotic (human umbilical vein endothelial cells (HUVEC)) cellular function were evaluated. HUVEC and bacterial oxidative stress responses, the accumulation of nitrite in aqueous media, air ion density, and bacterial inactivation at various distances from SDBD actuators were measured. SDBD actuator designs were also varied in terms of electrode number and length to evaluate the cellular effects of plasma volume and power distribution. NO and ions were found to contribute minimally to the observed cellular effects, whereas ROS were found to cause rapid bacterial inactivation, induce eukaryotic and prokaryotic oxidative stress, and result in rapid oxidation of bovine muscle tissue. The results of this study underscore the dominance of ROS as the major plasma generated species responsible for cellular effects, with ions and RNS having a secondary, complimentary role.

Cold Atmospheric plasma has been studied extensively over the last decade with applications ranging from bacterial decontamination to wound healing. Although numerous designs of plasma applicators have been developed for direct exposure, prolonged exposure required for decontamination of tissues and skin may be detrimental to mammalian cells. In this study, we evaluate the effect of plasma generated by surface dielectric barrier discharge (SDBD) on mammalian cells, including HUVEC, Neuroblastoma, and HepG2. SDBD actuator induces flow and can transport plasma‐generated species to the surface being treated. Cell morphology, viability, and functionality are evaluated by incubating cells after exposure to SDBD for 1, 4 and 8 min. All cell types demonstrate retention of viability without any necrotic response, although, with an increase in the number of injured cells, with increase in exposure time. Cell‐specific responses are observed with HUVEC demonstrating highest resilience as compared to neuroblastoma and HepG2 (lowest). Migration assay using HUVEC shows no effect on viability and functionality with 4 min exposure. The 8 min tests demonstrated no additional change in morphology, so we conclude that SDBD does not affect the cell morphology at longer exposure durations as compared to other plasma sources and can be applied safely in medical applications.

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OBJECTIVE To determine whether a stainless steel implant sterilized with a novel cold atmospheric plasma sterilization (CAPS) device adversely affects local tissues in rabbits and whether CAPS was as effective as steam sterilization with an autoclave to inactivate Pasteurella multocida. ANIMALS 31 healthy New Zealand White rabbits. PROCEDURES Steam-autoclaved stainless steel implants inoculated with P multocida underwent a second steam autoclave sterilization (AIA) or CAPS (AICAPS). One AIA implant and 3 AICAPS implants were randomly placed subcutaneously at 4 sites in 21 rabbits (84 implants). These rabbits were monitored daily for 5 days for evidence of systemic illness and local tissue reactions at the implantation sites and then euthanized. Samples were taken from each implant site for bacterial culture and histologic examination. RESULTS Cultures of samples obtained from all sites were negative for bacterial growth. No significant difference was observed in mean skin thickness or erythema between AIA and AICAPS implant sites on any observed day. Also, individual histologic grades for the epidermis, dermis, subcutis, and muscle and total histologic grade were not significantly different between AIA and AICAPS implant sites. CONCLUSIONS AND CLINICAL RELEVANCE Cold atmospheric plasma sterilization was noninferior to steam sterilization of P multocida–contaminated stainless steel implants in the rabbits in the present study. However, studies of the efficacy of CAPS for inactivation of other important bacteria are needed.

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Dielectric Barrier Discharge (DBD) plasma is investigated experimentally to assess sterilization characteristics. DBD plasma is known to be capable of decontaminating materials of bacteria with a treatment time of the order of minutes or less. The four key factors that effect spore inactivation in plasma treatment are heat, UV radiation, free radicals and ions. The inactivation of spores is mostly due to the Lorentzian collisions between the ionized fluid of the plasma and the neutral air, which creates a motive force causing the active species formed to impact onto the contaminant. In this paper we demonstrate using Escherichia coli as the test specimen a 5-log reduction in the total cultivable number of cells within minutes of exposure. We also discuss the mixing characteristics produced by a cylindrical actuator configuration used for enhanced decontamination.

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