バイオテクノロジーとバイオマテリアル

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Characterization, Properties and Applications of Nonthermal Plasma: A Novel Pulsed-Based Option

James R Ferrell1, Aleksandr S Galov2, Valery A Gostev2, Bruce A Banks3, Steven P Weeks4, Judith A Fulton5 and Christopher J Woolverton6

 The glow discharge from a novel spark-based nonthermal plasma generator is described and characterized using spectrophotometry, radiometry and gas detectors. Spectral information identified ultraviolet radiation within the plasma discharge. High levels of reactive oxygen and nitrogenous species were also detected within the analyzed plasma. The plasma discharge is found to have a significant germicidal effect on Gram-positive bacteria, independent of temperature increase. The ultraviolet radiation and ionized gaseous species are found to contribute to this observed effect, synergistically. Plasma filtration reduced germicidal survivability significantly. The liquid environment in which bacterial cells were exposed to the nonthermal plasma also was important, when determining the efficacy of nonthermal plasma, as a germicidal agent. Staphylococcus aureus cultures exposed to nonthermal plasma for two minutes within low nutrient sources, such as water or phosphate-buffered saline, had very low survival. Cultures exposed to the same plasma interval in nutrient rich liquids tolerated the plasma exposure better, and survived at higher numbers. This plasma discharge is highly bactericidal, due to the high concentrations of known antimicrobial agents, but its effectiveness is subject to a synergistic effect, that depends upon the surrounding environment.