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As carbon monoxide has a broad spectrum of biological activities, its production by plasma is a significant advantage in medicine. This paper presents a comparative study of the CO production of two plasma jets: a MHz‐jet and a kHz‐jet. Both were fed with a helium gas with CO2 ${\text{CO}}_{2}$ admixture (0%–1%). CO was produced by CO2 ${\text{CO}}_{2}$ dissociation and its maximal concentration was hundreds of parts per million, which is safe for clinical applications. For the same specific energy input, the CO production was more efficient for the kHz‐jet than the MHz‐jet. Both had antibacterial properties on Escherichia coli, and the addition of CO2 ${\text{CO}}_{2}$ improved them for the MHz‐jet, while it reduced them for the kHz‐jet. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) has anti-inflammatory properties and its production by plasma could be a significant advantage in the field of plasma medicine. We characterized a pulsed kHz-driven plasma jet to produce CO for biomedical applications. With no target interaction, the CO2 conversion into CO, the breakdown voltage and energy delivered to the plasma were investigated for two noble carrier gases: helium and argon. The breakdown voltage and the energy delivered to the plasma in argon gas were twice as high as in helium. The breakdown voltage was barely affected by the gas flow rate and the applied voltage, while it decreased slightly with the excitation frequency because the amount of residual charges increases with the frequency. However, the energy delivered to the plasma was not particularly affected by a change in frequency or gas flow rate, while it increased linearly with the applied voltage. CO production rose from a couple of ppm to about 2000 ppm for a specific energy input from 2 to 2000 J/L (5 × 10−4 to 5200 × 10−4 eV/(atom or molecule)), making this plasma source safe in terms of CO production for biomedical applications. Unlike literature results, the nature of the noble carrier gas did not have an impact on CO production. The CO concentration produced with 0.3% CO2 admixture increased linearly with the specific energy input (SEI) until reaching a plateau at about 2100ppm. This implies that loss processes were negligible and that CO2 dissociation was mainly due to energetic particles such as electrons and excited noble atoms. The conversion decreased with the ratio of CO2. Helium and argon as carrier gases are equivalent in terms of CO production and the CO concentration can be controlled by the SEI and the ratio of CO2. [ABSTRACT FROM AUTHOR]

Featured Application: The objective of the work is to assess the use of non-thermal multi plasma jets for the treatment of infected and chronic wounds in the context of hospital centers. This work is a contribution to the development and implementation of non-thermal plasma technology for decontamination in the perspective of nosocomial and chronic wound innovative therapies. Multi jets devices based on Plasma Gun® technology in static and scanning operation modes and bacterial lawns inoculated with resistant and non-resistant bacterial strains were designed and used. A pilot toxicity study exploring plasma treatment of wound bearing patients, performed with a low voltage plasma applicator, is documented as a first step for the translation of in vitro experiments to clinical care. Bacterial inactivation was demonstrated for Staphylococcus aureus, Pseudomonas aeruginosa and drug resistant S. aureus, P. aeruginosa and Escherichia Coli strains collected from patient wounds at Orleans (France) hospital. A few square centimeter large contaminated samples were inactivated following a single plasma exposure as short as one minute. Samples inoculated with a single but also a mix of three resistant pathogens were successfully inactivated not only right after their contamination but for mature lawns as well. Similar bactericidal action was demonstrated for antibiotic-resistant and non-resistant P. aeruginosa. The time exposure dependent increase of the inhibition spots, following multi jets exposure, is discussed as either the accumulation of reactive species or the likely combinatory action of both the reactive species and transient electric field delivery on inoculated samples. [ABSTRACT FROM AUTHOR]

A new method to deliver carbon monoxide (CO) for medical applications is presented using a kHz‐driven helium plasma jet with a 1% CO2 admixture. Despite being known for its anti‐inflammatory, vasorelaxing, and anti‐apoptotic effects, a possible role of CO generated from plasma for the treatment of various diseases has so far been neglected. Here, we show that CO production of a plasma jet can be tuned from 100 to 2000 ppm. The number of CO molecules produced per pulse is in the range of 1 × 1012 to 1.5 × 1013. To assess the delivery of CO, mouse blood hemoglobin was used as a scavenger of CO and the consequent formation of carboxyhemoglobin was quantified. This study reveals for the first time that plasma can generate and deliver CO for therapeutic interventions. [ABSTRACT FROM AUTHOR]

"Plasma Processes & Polymers" is an interdisciplinary journal that focuses on low temperature plasma science. It covers both experimental and theoretical research in materials science, physics, chemistry, and engineering related to plasma sources and plasma-based treatments. The journal aims to provide a platform for researchers to share their findings in this field. The front cover of the journal features an image by Eloïse Mestre, Inna Orel, Daniel Henze, Laura Chauvet, Sebastian Burhenn, Sébastien Dozias, Fabienne Brulé‐Morabito, Judith Golda, and Claire Douat. [Extracted from the article]

Because of their capabilities to generate plasmas that are not confined between electrodes, low-temperature plasma jets offer unique opportunities for applications such as material processing and biomedicine. The need to generate multiple jets in order to cover larger treatment areas has recently become desirable. However, the interaction between neighbouring jets is unavoidable. It is therefore crucial to elucidate the physical processes that occur between jets. In this paper we present the case of two counter-propagating jets generated by two DBD-based devices. We show that the plasma bullets emitted by the two jets interact with each other as soon as they leave their respective DBD device, resulting in a decrease in their velocities. The bullets do not actually meet but rather approach each other at a minimum approach distance. The location of the region of minimum approach is not midway between the nozzles of the jet devices but rather depends on the operating conditions. In addition, we discovered the emergence of a 'secondary' discharge exactly in the region of minimum approach. This discharge exhibits a pink glow, reminiscent of the pink afterglow occurring in some nitrogen discharges. Time-resolved spectroscopic measurements and current measurement analysis showed that the pink glow is a transient negative glow discharge that cannot be attributed to kinetic processes associated with re-excitation of nitrogen molecules. It is rather ignited by electrons accelerated from both jets towards the region of minimum approach. This process is found to be exactly timed with the measured current reversal. [ABSTRACT FROM AUTHOR]

The effectiveness of electrochemotherapy (ECT) in local eradication of tumours in human and veterinary medicine has been proven. ECT consists of increasing the uptake of cytotoxic drugs by means of pulsed electric fields (PEFs) that transiently permeabilise the cell membrane. Still, this tumour treatment includes some drawbacks that are linked to the characteristics of the intense electric pulses (EPs) used. Meanwhile, the emerging field of cancer therapies that are based on the application of non-thermal plasmas (NTP) has recently garnered interest because of their potentialities as rich sources of reactive species. In this work, we investigated the potential capabilities of the combined application of indirect NTP treatment and microsecond PEFs (µsPEFs) to outperform in vitro cell electropermeabilisation, the basis of ECT. Thus, phosphate-buffered saline (PBS) was plasma-treated (pPBS) and used afterwards to explore the effects of its combination with µsPEFs. Analysis of two different cell lines (DC-3F Chinese hamster lung fibroblasts and malignant B16-F10 murine melanoma cells), by flow cytometry, revealed that this combination resulted in significant increases of the level of cell membrane electropermeabilisation, even at very low electric field amplitude. The B16-F10 cells were more sensitive to the combined treatment than DC-3F cells. Importantly, the percentage of permeabilised cells reached values similar to those of cells exposed to classical electroporation field amplitude (1100 V/cm) when the cells were treated with pPBS before and after being exposed only to very low PEF amplitude (600 V/cm). Although the level of permeabilisation of the cells that are treated by the pPBS and the PEFs at 600 V/cm is lower than the level reached after the exposure to µsPEFs alone at 1100 V/cm, the combined treatment opens the possibility to reduce the amplitude of the EPs used in ECT, potentially allowing for a novel ECT with reduced side-effects. [ABSTRACT FROM AUTHOR]

Tunable diode laser absorption spectroscopy was used to measure the spatio-temporal evolution of helium metastable atoms He (2^3S) in an atmospheric plasma jet. The production of these atoms is clearly correlated to the propagation of an ionization wave, the so-called plasma bullet. Whatever the applied voltage, the spatial structure of the density rapidly evolves from a donut shape to a conical form as the plasma propagates. For applied voltages higher than 4.5 kV, a complex transient structure appears at the tip of the jet. [ABSTRACT FROM PUBLISHER]

Cold plasma jets produced by pulsed discharges have recently attracted a lot of attention because of their unusual physical properties enabling the development of new applications, particularly for plasma medicine. ICCD pictures of these jets revealed that they were not continuous plasmas but composed of plasma bullets propagating at very high velocity. In this paper, pictures of the interaction of two counterpropagating bullets have been taken to give insights into the physics of the bullets and to clarify which kind of models could be relevant to describe the bullet properties. [ABSTRACT FROM AUTHOR]