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Cold atmospheric pressure plasmas have emerged as a promising new tool for medical applications. Compared to conventional thermal plasma, such as arc coagulators and desiccators, cold plasma can be more selective in its application and may be used for effective sterilization of skin and wound tissue, wound healing and tissue regeneration, cancer treatment and blood coagulation. One of the key questions that has to be answered before these plasma technologies are introduced in medical practice is the safety of plasma treatment of living tissues, i.e. toxic dose levels of plasma exposure should be determined. It is well established that porcine (pig) skin closely resembles human skin; hence we evaluated the potential toxic effects of plasma treatment on intact and wounded skin in a Yorkshire pig model. Varying doses of Floating Electrode Dielectric Barrier Discharge (FE-DBD) and microsecond Pin-to-Hole Spark Discharge (PHD) plasmas were applied to determine a dosage regime where tissue damage occurs.

A lab-scale, tunable, single-filament, point-to-point nonthermal dieletric-barrier discharge (DBD) plasma device was built to study the mechanisms of inactivation of aerosolized bacterial pathogens. The system inactivates airborne antibiotic-resistant pathogens efficiently. Nebulization mediated pre-optimized (4 log and 7 log) bacterial loads were challenged to plasma-charged aerosols, and lethal and sublethal doses determined using colony assay, and cell viability assay; and the loss of membrane potential and cellular respiration were determined using cell membrane potential assay and XTT assay. Using the strategies of Escherichia coli wildtype, over-expression mutant, deletion mutants, and peroxide and heat stress scavenging, we analyzed activation of intracellular reactive oxygen species (ROS) and heat shock protein (hsp) chaperons. Superoxide dismutase deletion mutants (ΔsodA, ΔsodB, ΔsodAΔsodB) and catalase mutants ΔkatG and ΔkatEΔkatG did not show significant difference from wildtype strain, and ΔkatE and ΔahpC was found significantly more susceptible to cell death than wildtype. The oxyR regulon was found to mediate plasma-charged aerosol-induced oxidative stress in bacteria. Hsp deficient E. coli (ΔhtpG, ΔgroEL, ΔclpX, ΔgrpE) showed complete inactivation of cells at ambient temperature, and the treatment at cold temperature (4°C) significantly protected hsp deletion mutants and wildtype cells, and indicate a direct involvement of hsp in plasma-charged aerosol mediated E. coli cell death.

Summary Background Onychomycosis affects almost 6% of the world population. Topical azoles and systemic antifungal agents are of low efficacy and can have undesirable side effects. An effective, non‐invasive therapy for onychomycosis is an unmet clinical need. Objective Determine the efficacy threshold of non‐thermal atmospheric plasma (NTAP) to treat onychomycosis in an in vitro model. Methods A novel toe/nail‐plate model using cadaver nails and agarose media inoculated with Candida albicans was exposed to a range of NTAP doses. Results Direct exposure of C albicans and Trichophyton mentagrophytes to 12 minutes of NTAP results in complete killing at doses of 39 and 15 kPulses, respectively. Onset of reduced viability of C albicans to NTAP treatment through the nail plate occurs at 64 kPulses with 10× and 100× reduction at 212 and 550 kPulses, respectively. Conclusions NTAP is an effective, non‐invasive therapeutic approach to onychomycosis that should be evaluated in a clinical setting.

In this article we report initial experiments applying nonequilibrium atmospheric pressure, pulsed, floating electrode dielectric barrier discharge in ophthalmology. We show that plasma can be applied to the eye both ex vivo in explanted pig eyes and in vivo in live rabbits and pigs. The results show effective sterilization below the threshold of significant damage to the cornea. This research is in the initial stages but is instrumental in the understanding of plasma's ability to become a novel therapeutic tool in ophthalmology.