Remote delivery of hydroxyl radicals via secondary chemistry of a nonthermal plasma effluent

Plimpton, S. Reed; Gołkowski, Mark; Mitchell, David; Austin, Chad; Golkowski, C.; Voskuil, Martin I.

doi:10.1002/bit.24853

Cited by 24 publications

(28 citation statements)

References 50 publications

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“…Higher humidity of the process gas led to higher inactivation rates and this was attributed to the formation and impact of hydroxyl radicals (Hähnel et al ). However, since the gas‐phase lifetime of hydroxyl radicals is reported to be very short, it is unlikely that hydroxyl radicals created in the discharge reach the target in a remote operation mode when the distance to the treatment site is more than 1 cm (Plimpton et al ). But even though hydroxyl radicals represent a short‐lived species, their contribution to the sporicidal effect cannot be ruled out, since at high humidity, they might be produced by the reaction of the long‐lived species such as ozone with water molecules close to the sample surface (Jeon et al ).…”

Section: Discussionmentioning

confidence: 99%

Inactivation of bacterial endospores on surfaces by plasma processed air

Krämer

Hasse

Guist

et al. 2020

Journal of Applied Microbiology

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Aims In case of biological hazards and pandemics, personal protective equipment of rescue forces is currently manually decontaminated with harmful disinfectants, primarily peracetic acid. To overcome current drawbacks regarding supply, handling and disposal of chemicals, the use of plasma processed air (PPA) represents a promising alternative for surface decontamination on site. In this study, the sporicidal efficiency of a portable plasma system, designed for field applications, was evaluated. Methods and Results The developed plasma device is based on a dielectric barrier discharge (DBD) and operated with ambient air as process gas. PPA from the plasma nozzle was flushed into a treatment chamber (volume: 300 l) and bacterial endospores (Bacillus subtilis and Bacillus atrophaeus) dried on different surfaces were treated under variable conditions. Reductions in spores by more than 4 log10 were found within 3 min of PPA exposure. However, the presence of endospores in agglomerates or in an organic matrix as well as the complexity of the respective surface microstructure negatively affected the inactivation efficiency. When endospores were embedded in a dried protein matrix, mechanical wiping with swabs during exposure to PPA increased the inactivation effect significantly. Gaseous ozone alone did not provide a sporicidal effect. Significant spore inactivation was only obtained when water vapour was injected into the PPA stream. Conclusion The results show that endospores dried on surfaces can be reduced by several orders of magnitude within few minutes in a treatment chamber which is flushed with PPA from of a DBD plasma nozzle. Significance and Impact of the Study Plasma processed air generated on site by DBD plasma nozzles could be a suitable alternative for the disinfection of various surfaces in closed rooms.

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Section: Discussionmentioning

confidence: 99%

Inactivation of bacterial endospores on surfaces by plasma processed air

Krämer

Hasse

Guist

et al. 2020

Journal of Applied Microbiology

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“…Several nonthermal plasma generators display higher levels of hydroxyl radicals, compared with non-water vapor plasma discharges, when supplied with water vapor [18,19,25]. Alteration of the amount of oxygen in the starting plasma, gaseous medium has been shown to affect the amount of nitrogen oxide during association with nitrogen.…”

Section: Plasma Spectra Characteristicsmentioning

confidence: 99%

“…Several recent studies have referenced the use of water vapor in the generation of nonthermal plasma. These studies have identified discharge spectra profiles, composed of elevated hydroxyl radicals and hydrogen peroxide [18,19]. This current paper does not discuss the use of humidified air or water vapor as a source of plasma starting material.…”

Section: Introductionmentioning

confidence: 99%

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

Ferrell¹,

Aleks²,

Galov³

et al. 2013

J Biotechnol Biomaterial

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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.

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“…Plasma, a partially ionized gas, has proven to have a broad range of industrial and biomedical applications (Bogaerts et al, ; Chen, ; Daeschlein et al, ; Fricke et al, ; Kolacyak et al, ; Park et al, ; Plimpton et al, ). Cold atmospheric plasma (CAP) in general is plasma generated at atmospheric pressure and its rotational temperatures (gas temperatures) are close to ambient temperatures.…”

Section: Introductionmentioning

confidence: 99%

Induction of apoptosis in human myeloid leukemia cells by remote exposure of resistive barrier cold plasma

Thiyagarajan

Anderson

Gonzales

2013

Biotech & Bioengineering

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Cold atmospheric plasma (CAP), an ambient temperature ionized gas, is gaining extensive interest as a promising addition to anti-tumor therapy primarily due to the ability to generate and control delivery of electrons, ions, excited molecules, UV photons, and reactive species such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) to a specific site. The heterogeneous composition of CAP offers the opportunity to mediate several signaling pathways that regulate tumor cells. Consequently, the array of CAP generated products has limited the identification of the mechanisms of action on tumor cells. The aim of this work is to assess the cell death response of human myeloid leukemia cells by remote exposure to CAP generated RNS by utilizing a novel resistive barrier discharge system that primarily produces RNS. The effect of variable treatments of CAP generated RNS was tested in THP-1 cell (human monocytic leukemia cell line), a model for hematological malignancy. The number of viable cells was evaluated with erythrosine-B staining, while apoptosis and necrosis was assessed by endonuclease cleavage observed by agarose gel electrophoresis and detection of cells with the exclusionary dye propidium iodide and fluorescently labeled annexin-V by flow cytometry and fluorescent microscopy. Our observations indicate that treatment dosage levels of 45 s of exposure to CAP emitted RNS-induced apoptotic cell death and for higher dosage conditions of ≥50 s of exposure to CAP induced necrosis. Overall the results suggest that CAP emitted RNS play a significant role in the anti-tumor potential of CAP.

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Remote delivery of hydroxyl radicals via secondary chemistry of a nonthermal plasma effluent

Cited by 24 publications

References 50 publications

Inactivation of bacterial endospores on surfaces by plasma processed air

Inactivation of bacterial endospores on surfaces by plasma processed air

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

Induction of apoptosis in human myeloid leukemia cells by remote exposure of resistive barrier cold plasma

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