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International audience; Carbon monoxide (CO) has a bad reputation due to the potentially lethal consequences when inhaled at high concentrations. However, at low doses CO appears to have many beneficial effects for human health and has a broad spectrum of biological activities such as anti-inflammatory, vasodilatory, anti-apoptotic, and anti-proliferative effects [1]. Plasma can generate CO from the dissociation of CO2, and in this context, non-equilibrium plasma at atmospheric pressure is an attractive in situ CO source, since it is able to create CO at low doses from CO2 [2]. Moreover, plasma can be used for biomedical applications and intense research is now being conducted on the potential therapeutic use of plasma for the treatment of different pathologies including cancer and skin wounds. Plasmas are very versatile as they possess the capacity to generate large amounts of reactive species combined with electric field, photons and charged particles. However, the combination of plasma and CO for biomedical applications remains to be fully explored. This presentation will focus on the challenge to develop a plasma reactor to generate controlled quantities of CO that can be used for therapeutic purposes. The reactor is based on plasma jet configuration where the discharge is produced in a coaxial dielectric barrier discharge (DBD) reactor equipped with a quartz capillary tube [3]. Helium with small addition of CO2 goes through the device. To assess and quantify the production of CO from plasma, we developed a system whereby mouse blood hemoglobin, a strong scavenger of CO, interacted with the plasma reaction. Once CO binds to hemoglobin, it forms carboxyhemoglobin (COHb), which can be precisely quantified by light absorption. We will present the first results showing that an indirect and a direct plasma treatment have a different influence on the production of CO and its binding to hemoglobin. [1]B. E. Mann and R. Motterlini, Chem. Commun., no. 41, p. 4197, 2007.[2]E. Carbone and C. Douat, Plasma Med., vol. 8, no. 1, pp. 93–120, 2018.[3]T. Darny, J.-M. Pouvesle, V. Puech, C. Douat, S. Dozias, and E. Robert, Plasma Sources Sci. Technol., vol. 26, no. 4, p. 045008, Mar. 2017.

International audience; Carbon monoxide (CO) has a bad reputation due to the potentially lethal consequences when inhaled at high concentrations. However, at low doses CO appears to have many beneficial effects for human health and has a broad spectrum of biological activities such as anti-inflammatory, vasodilatory, anti-apoptotic, and anti-proliferative effects [1],[2]. Plasma can easily generate CO from the dissociation of CO2, as it has been demonstrated in the laser and energy storage fields [3], [4]. In this context, non-equilibrium plasma at atmospheric pressure is an attractive in situ CO source, since it is able to create CO at low doses from CO2 [5]. Moreover, plasma can be used for biomedical applications and intense research is now being conducted on the potential therapeutic use of plasma for the treatment of different pathologies including cancer and skin wounds. Plasmas are very versatile as they possess the capacity to generate large amounts of reactive species combined with electric field, photons and charged particles. Among these are reactive oxygen and nitrogen species (RONS), such nitric oxide (NO), which are produced by the interaction of the plasma with air. NO is widely studied in the field of Plasma Medicine due to its biological role as signaling molecule that functions very similarly to CO [6]–[8]. In fact, CO and NO could be highly complementary due to the different chemical reactivity of these two gases with intracellular cellular targets. However, the combination of plasma and CO for biomedical applications remains to be fully explored. This contribution will focus on the challenge to develop a plasma reactor to generate controlled quantities of CO that can be used for therapeutic purposes. The reactor is based on plasma jet configuration where the discharge is produced in a coaxial dielectric barrier discharge (DBD) reactor equipped with a quartz capillary tube [9]. Helium with small addition of CO2 goes through the device. To assess and quantify the production of CO from plasma, we developed a system whereby mouse blood hemoglobin, a strong scavenger of CO, interacted with the plasma reaction. Once CO binds to hemoglobin, it forms carboxyhemoglobin (COHb), which can be precisely quantified by light absorption. We will present the first results showing that an indirect and a direct plasma treatment have a different influence on the production of CO and its binding to hemoglobin. References[1]R. Motterlini & R. Foresti, Am. J. Physiol. Cell Physiol, vol. 312, n. 3, C302, (2017).[2]R. Motterlini & L. E. Otterbein, Nature Rev. Drug Discov., vol. 9, n. 9, 728, (2010).[3]H. Hokazono & H. Fujimoto, J. Appl. Phys., vol. 62, no. 5, 1585–1594, (1987).[4]A. Lebouvier, S. A. Iwarere, et al., Energy & Fuels, vol. 27, no. 5, 2712–2722, (2013).[5]C. Douat, P. E. Bocamegra, et al., in 24th International Symposium on Plasma Chemistry, 2019.[6]D. B. Graves, IEEE Trans. Radiat. Plasma Med. Sci., vol. 1, no. 4, 281–292, (2017).[7]E. Carbone & C. Douat, Plasma Med., vol. 8, no. 1, 93–120, (2018).[8]V. N. Ayyagari, A. Januszkiewicz, et al., Toxicology, vol. 197, no. 2, 148–163, (2004).[9]T. Darny, J.-M. Pouvesle, et al., Plasma Sources Sci. Technol., vol. 26, no. 4, 045008, (2017).

International audience; The potential beneficial impact of plasma is being investigated for many biotechnological and medical applications. However, translating promising in vitro results to in vivo (bio)medical outcomes remains a challenging task. One of the major challenges in the translation of plasma technologies to in vivo, and ultimately clinical use, is the lack in the fine control necessary for an efficient and safe use of plasma sources in medical applications; this we attribute to the mutual interaction between plasma and target [1]. Many key fundamental questions on the mechanisms taking place at the interface between plasma and (bio) targets still need to be addressed. While there is an abundance of literature on the biological effects of plasma treatment, there are only a few reports on the physico-chemical characterization of the plasma during the treatment process. Even considering a very simple scenario using a plasma jet to treat a 2D culture of cells in a plastic multi-well plate, it is not known in detail how the physical environment of the micro-well may influence the biological effects of the plasma. Recent research has reported how the geometry of the multi-well plate, as well as the electrical characteristics of the support on which it stands, can have a significant impact on the experiment and its reproducibility [1, 2]. Furthermore, the presence or absence of a liquid and small variations in its depth/volume can completely change the nature and the distribution of the bioactive plasma-generated RONS reaching the bottom of the well [3].As it will be presented, surprisingly, even in small liquid volumes (e.g. 0.2–2 ml) typical of biomedical in vitro experiments, the impinging plasma jet on the biological liquid can induce the formation of fast and complex electro fluid dynamic (EFD) flows. These flows are affected by plasma parameters and can lead to vortex recirculation. Whereas biological effects will always be the focus of plasma medicine, it is important for the advancement of this field to achieve a deeper understanding and a greater awareness of the physico-chemical processes taking place during our plasma biomedical experiments.Acknowledgements: PLASCANCER (INCa-PlanCancer N°17CP087-00), GdR 2025 HAPPYBIO and and ERC APACHE Nº714793).References[1] A. Stancampiano, T.-H. Chung, S. Dozias, J.-M. Pouvesle, L. M. Mir, and E. Robert, IEEE Trans. Radiat. Plasma Med. Sci., Early Acess, 10.1109/TRPMS.2019.2936667 (2019)[2] S. Mohades, A. Lietz, J. Kruszelnicki and M. Kushner, Plasma Process. Polym, e1900179 (2019)[3] S. Sasaki, R. Honda, Y. Hokari, K. Takashima, M. Kanzaki and T. Kaneko, J. Phys. D: Appl. Phys, 49, 334002 (2016)

International audience; Following in vitro assessment of cancer cells and the benefit of a combined treatment based on incubation with plasma treated solution and application of Pulsed Electric Field in the context of reversible cell membrane permeabilization, this work reports on the in vivo evaluation of such combined innovative antitumor approach. Three independent studies, dealing with immunocompetent mice bearing fibrosarcoma tumors and involving control groups, PEF treated group (Bleomycine Electro Chemo Therapy (ECT) and combined plasma treated PBS (p-PBS) and PEF treatments, were performed. A single-shot treatment was applied 12 days after tumor cell injection, and follow up of tumor volume was performed for more than two months. The main conclusions of these studies indicate that (i) p-PBS production and storage was highly reproducible and allow for in vivo studies requiring large volume of such solutions; (ii) Bleomycin, p-PBS, and their combined injection has no antitumor action; (iii) ECT as a reference therapy is efficient, especially for fast growing tumors; (iv) combined p-PBS and ECT treatment allow for a slower tumor growthrate, for fast growing tumors, and lead to a significant increase of the number of tumor regressions; and (v) composition of p-PBS solution for different plasma exposures might be a unique parameter for a fine tuning of the efficiency of the combined antitumor treatment.

International audience; Plasma jets are being intensively researched for cancer therapy with encouraging initial clinical outcomes already realised. However, the fine control of plasma jets remains challenging due to the mutual interaction between plasma and target [1]. Even considering perhaps one of the simplest scenarios in a research laboratory, using a plasma jet to treat a 2D culture of cells in a plastic multi-well plate, it is not known in detail how the physical environment of the micro-well may influence the nature of the plasma jet treatment. This study aims to shed light into this topic by investigating how electro fluid dynamic (EFD) flows influence the delivery of the bioactive plasma-generated RONS when a plasma jet is used to treat a conductive biologically-relevant liquid (i.e. PBS) in a standard tissue culture grade 24-well plate [2]. The results show how the formation of complex EFD flows in the liquid induce a non-uniform distribution of the RONS, especially within the first few seconds of treatment (Fig. 1a). Shortly after the ignition of the plasma jet an initial rapid liquid stream can reach the bottom of the well, whereas a stable vortex mixing is observed few seconds later (Fig. 1b). Experimental results indicate that electric charge accumulation on the liquid surface and plasma induced gas swirling could be the causes of the liquid motions. Furthermore, the liquid depth and the voltage polarity were found to be critical parameters in controlling the delivery of the RONS to the bottom of the well. A multijet plasma source was, then, used for the treatment of PBS (pPBS), which was combined with a pulsed electric field (PEF) to permeabilise B16-F10 murine melanoma cells. Compared to PEF alone, the combined treatment with pPBS (applied before and after PEF exposure) can greatly increase the number of permeabilised cells and the uptake of a model non-permeant molecule (Yo-Pro®-1) to confirm the permeability of the cell membrane (Fig. 1c). This synergistic effect of plasma treated PBS and PEF could open new opportunities for the application of plasma jets in electrochemotherapy

International audience; We target and report on the use of either single or multi so-called cold atmospheric pressure plasma jets, based on Plasma Gun technology [1], to expose liquid solutions eventually containing seeds or immerged seedlings for agricultural applications. Besides, the upscaling capability of multi jet setups in comparison with single jet devices for the generation of attractive chemicals in solutions, the consideration of the diffusion of plasma produced reactive species in liquid samples is the focus of our investigations. With the single jet configuration, two mode of exposures of liquid samples are considered: a “conventional” protocol where plasma jet plume impinges on the top of the solution and a more rarely investigated and documented method where the plasma jet is “transferred” into gas bubbles exiting from an immerged nozzle [2]. The talk will report on in-bubble plasma generation, water solution treatment using bubble plasma gun device, and the diffusion of reactive species in the liquid container. Using KI coloration as a broad range oxidation reporter, it is measured that while conventional plasma jet exposure leads to very slow and very inhomogeneous reactive species diffusion in the solution, generation of plasma in bubbles induces a sudden, very homogeneous and surprising oxidation of the whole volume of a few mL. Work is in progress to try and simulate the plasma generation in bubble and the consecutive reactive species delivery in the solution. With the conventional protocol, Schlieren visualization indicates that air and helium mixing and flow properties above the liquid surface correlates with the oxidation patterns revealed in the solution. Air entrainment along and inside the plasma plume with plasma jet in free jet mode or impinging over various targets was recently reported with a dielectric barrier discharge based helium plasma jet [3]. Dealing with plasma solution generation using plasma jet and/or treatment of solution containing either attached or suspended cells or samples of interest for agriculture, it is suspected that neither slow diffusion using conventional plasma jet exposure nor opportunity with bubble arrangement were so far considered with sufficient care.References [1] JM Pouvesle, C Cachoncinlle, R Viladrosa, A Khacef, E Robert, S Dozias, Transient plasma ball generation system at long distance, US Patent 8,482,206 [2] A. Hamon, C. Douat, S. Dozias, J.M. Pouvesle, E. Characterization of plasma generation in bubbles with a plasma gun. 22nd International Conference on Gas Discharges and Their Applications GD2018, Inst. Phys. Belgrade; SASA; Univ. Belgrade, Sep 2018, Novi Sad, Serbia. hal-01943383 [3] Y Morabit, RD Whalley, E Robert, MI Hasan, JL Walsh, Turbulence and entrainment in an atmospheric pressure dielectric barrier plasma jet, Plasma Processes and Polymers, e1900217

International audience; This work reports on the interaction of so-called plasma jet with or within liquid solutions. The use ofthe Plasma Gun as an archetypical setup for processing liquid samples or humid tissues in thecontext on plasma biomedical applications but also in a more innovative configuration where plasmajet is immersed in solution to generate plasma in gas bubbles will be discussed. In the "abovesolution" setup, recent experiments have shown that reactive species generation and delivery in theliquid could be very non intuitive, revealing the existence of steady state vortexes, surfaceaccumulation zones, needle-like transient patterns, ... depending on various operating conditionssuch as gas flow, pulse repetition rate, distance to the sample, while being quite universal for variousliquid containers typically used for biomedical applications. Conversely, the in-bubble plasmageneration while being very dependent on the operating conditions as well and on the liquid electricalconductivity, is shown to allow for a, at a first glance surprising, very fast and very homogenousdelivery of reactive species in liquid samples. Plasma generation is gas bubbles will be documented,together with the reactive species generation efficiency versus gas flow rate, number of plasma pulsedelivery in a single bubble. It is shown that plasma generation in gas bubble has drastic impact on thebubble expansion dynamics and that synchronization of plasma pulse generation during the bubblelifetime could be a key parameter to optimize the reactive species generation and balance.Perspectives for multi bubble plasma reactors delivered in large liquid volume processing will bediscussed.

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International audience; The last decade has seen an impressive increase of the research dedicated to the biological applications of low temperature atmospheric pressure plasmas. Medical appli-cations are tacking an increasing place underlined by many clinical trials. They now concern numerous domains, including blood coagulation, dental care, skin decontamination and hygiene, wound and ulcer treatment, dermatology, cancer treatment. Biological applications are also now extended to agriculture and, more recently, to cosmetic. Despite the huge number of in vitro and in vivo experiments, there are still numerous challenges to overcome linked to the nature of the encountered target (biological tissues and materials, organs and their direct environment, liquids) that have a direct effect on the produced plasma itself and on the generated species. That must therefore be taken into account in the applied treatments and complicates the definition of a "plasma dose" expected by many.

International audience; Non-thermal plasmas, produced from dielectric barrier discharges in air or from rare gas plasma jet devices, generate at room temperature, long and short lifetime reactive species (RS) in gaseous phase or in the liquid solution on which they impinge, ionic species, UV photons and intense transient electric fields (EF). In the last decade, the main focus was drawn on the RS to understand and optimize their action in the frame of the broad topic of “Plasma medicine”. More recently, the characterization and implication of EF in biomedical applications is studied, considering the generation of ns to μs duration, kV/cm amplitude features of plasma EF. Plasma have been shown to be a potential alternative to more “conventional technologies” for gene transfer, cell permeabilization, drug delivery in various applications including for cancer therapy. Quite recently, the concepts of reversible electroporation, especially the models of so called pore formation in cell membranes were broaden and detailed involving not only the key role of EF but also the oxidation of cell membrane associated with RS. Thus it appears we attend to a unique opportunity to reach more insights and achieve cell manipulation process optimization with considering the potential complementary or synergistic delivery of pulsed electric fields and plasma for in vitro and in vivo protocols.Besides a quick overview of some significant works focused on the use of non-thermal plasmas in interaction with cell membranes, the lecture will document the results obtained so far with the Plasma Gun developed at GREMI for first, cancer cell permeabilization with various plasma delivery protocols, and second on the first demonstrations of the positive combined action of pulsed electric fields (PEF) and plasma for antitumor action. Cell permeabilization has been performed in vitro for different adherent cell lines, exposed to plasma jet delivered at various pulse repetition rates for short duration and followed with cell incubation in plasma treated solution. The combination of plasma and PEF is studied in vitro and with murine models considering the delivery of pulsed voltage and current pulses (electroporation) together with plasma treated solutions in contact with biological targets (suspended cancer cells in electroporation cuvettes or tumors) at different delays with respect to the electroporation step.AcknowledgmentsWork supported by PLASCANCER project INCa-PlanCancer-n°17CP087-00 and GDR CNRS 2025 HAPPYBIO

International audience; In this work we developed a plasma source based on a Plasma Gun reactor able to generate small quantities of CO. The production fraction of CO molecules has been measured ex-situ by means of gas chromatography. We showed that the density is in the 100-10000 ppm range. The CO concentration can be controlled by varying the gas mixture and by tuning the applied voltage. In CO clinical application, the typical dose used is in the range of 100-1000 ppm. It means that this plasma reactor is suitable as CO source for biological applications.

International audience; Biological applications of Low Temperature Non Thermal Plasmas (LTNTP) have underwent a very rapid development over the recent years and have, even more recently, attracted a lot of attention in the field of agriculture and related domains. Their ability to fight harmful microorganisms and to promote decontamination makes them particularly attractive in that they do not generate chemical residues that must be reprocessed. They are also very attractive to generate interesting reactive species in liquid media that can then be sprayed or used for watering or for soil fertilization. The quality of seeds not only includes their capacity of rapid germination and fruitful growth, but also their protection against, at least, major well know diseases that can threaten their development (for example diseases provoked by Tilletia caries or Ustilago tritici (smut) in the case of wheat). Taking into account the fact that, in the coming years, the new regulations will lead to the impossibility to use the up to now frequently used chemicals, seed producers will have to find new physical treatments if they don’t want to face problems when putting their production on the market. They are then facing another problem: physical treatment must cure seed from pathogens, but, at the same time, they must be totally safe for seed germination and grow. Also, the longer term effects on plants and potential gene modifications should be considered. Due to seed characteristics, especially design to survive in aggressive environments during the latency period, this represents a huge challenge not easy to overcome. LTNTP appear as a very interesting potential treatment in that domain, especially for very high added value seeds and slip, and can open new routes in agriculture processing.On one hand, due the complex nature of plasmas produced at atmospheric pressure in air, experiments must be conducted to allow determination of plasma components (at least RONS and specific species like CO, UV and Electric field) main action trends. On another hand, due to the increasing use of plasma treated water, it is suitable to find new ways of producing different cocktails of usable reactive species of agricultural interest. Experiments, dedicated to that, have been conducted on various seeds and discharge systems (including jet, multijets, volumic plasmas, low pressure plasmas, bubbling plasma treated water) and will be presented.

International audience; The last decade has seen an impressive increase of the research dedicated to the biomedical applications of low temperature plasmas, especially with plasma sources working at atmospheric pressure. In this new trend, beside decontamination/sterilization and surface treatment that have already a quite long story through low-pressure plasma research and developments, medical applications are tacking an increasing place underlined by the actual numerous clinical trials. Medical applications of low temperature plasmas now concern a very wide range of domains, including primary haemostasis and blood coagulation, dental care, skin decontamination and hygiene, wound and ulcer treatment, dermatology, cancer treatment. Biological applications are also now extended to agriculture and, more recently, to cosmetic. Despite the huge number of in vitro and in vivo experiments there are still numerous challenges to overcome linked to the nature of the encountered target (biological tissues and materials, organs and their direct environment, liquids) that have a direct effect on the produced plasma itself and on the generated species. It is clear that the extremely strong coupling between the characteristics of the plasma and those of the target, as already shown, will play a very important role in the results observed during the treatments. A variation in the chemical or physical characteristics of the target will involve significant differences in the gas flow, the local temperature, or the induced electric field, resulting de facto in variations in the production of the reactive species. It also concerns the transposition of the results between the in vitro and the in vivo experiments that are carried out under extremely different conditions, especially concerning the equivalent electric circuit of the reactor / plasma / biological target assembly. These problems directly affect the identification of the processes involved and currently limit the possibility of a definition of a "dose" in plasma treatments. Recently, study reported led to reflections on non-sustainable tumor response. The loss of effectiveness under long-term plasma treatment of cancer tissue opens questions about plasma application and protocol. It must be considered that the treated area is morphologically and chemically changing over the time, from activated surrounding to more normal tissues that are less humid and bacteriologically cleaner. This aspect is particularly important for the development of efficient systems and protocols in plasma cancer treatment but also for any other plasma therapeutically approaches. It induce a in real-time in situ control of plasma production and at longer term a protocol adaptation taking into account the biological target evolution. Some progress are already done in that domain

International audience; The parameters needed for helium plasma jet to induce a cell membrane permeabilization on cancerous cells for drug delivery purposes have been investigated. Using our optimal settings, different fluorescent molecular markers were used in order to determine pore size, opening kinetics and the importance of endocytosis in the process. It is shown that plasma induced chemistry but also electric field play a role in drug uptake and that endocytosis is one of the mode of membrane permeabilzation.

National audience

International audience; The last decade has seen an impressive increase of the research dedicated to the biomedical applications of low temperature plasmas, especially with plasma sources working at atmospheric pressure. In this new trend, beside decontamination/sterilization and surface treatment which have already a quite long story through low pressure plasma research and developments, medical applications are tacking an increasing place underlined by the actual numerous clinical trials. Medical applications of low temperature plasmas now concern a very wide range of domains, including primary hemostasis and blood coagulation, dental care, skin decontamination and hygiene, wound and ulcer treatment, dermatology, cancer treatment. Biological applications are also now extended to agriculture and, more recently, to cosmetic. Despite the huge number of in vitro and in vivo experiments there are still numerous challenges to overcome linked to the nature of the encountered target (biological tissues and materials, organs and their direct environment, liquids) that have a direct effect on the produced plasma itself and on the generated species. In this talk, after a presentation of the context, the plasma devices, and the main applications, we will focus on the different problems linked to the plasma/target interaction, including treatments of tissues and liquids. Beside the induced changes in gas flow, the radical production and the potential role of the strong electric field generated around the plasma plume of atmospheric plasma jet systems, we will discuss possible changes induced in microenvironment of living targets. Throughout this presentation, we will emphasize on the fact that plasma diagnostics must be performed in real treatment conditions. We will also tackle the main issues, challenges and opportunities linked to the control of these multimodal action of non-equilibrium cold plasmas on living organisms.

International audience; Plasma interactions with liquids has drawn much attention over the past few years considering the interest of water decontamination or treatment of pharmaceutical products. In this context, we studied the potential of low temperature plasmas created inside bubbles using a Plasma Gun (PG) from which the capillary exit is immersed into liquids. Plasma generation inside rare gas bubbles, as well as bubble growth and shape modifications were evidenced through timeresolved ICCD imaging. In this work, we performed experiments in distilled and tap water. For the same used gas, results clearly show that the plasma propagation inside the bubbles and the bubbles behaviour are strongly dependent of the liquid conductivity. These observations, not only, show the importance of the characteristicsof the liquid on the production of the reactive species, but also the importance of the evolution of these characteristics during the treatment time.

International audience; With the nowadays-rapid development of atmospheric plasma applications in the fields of medicine, decontamination, cosmetic and agriculture, researchers are confronted with the development of new sources for treating large surfaces or volumes or great quantities of liquid or material. Single plasma jets have allowed significant advances and the results are particularly promising, but likely to be limited in the future. The treatment times are indeed rather long due to the very small treated surface area or liquid volume resulting from the produced plasma. Surface DBDs, which allow treatment of quite large areas, quickly find their limits when surfaces are more complex or have great 3D structures. There is a real challenge to develop sources that allow treatment over larger areas while remaining practical and at a reasonable cost. The scale factor then becomes very important and must be treated with the outmost attention. In this context, after a rapid review of available systems, some new developments concerning single jets and plasma jets interactions with liquids, we will present results obtained on the development of the sources allowing to treat large surfaces or volumes realized from multijet systems emanating from a single discharge reactor. Examples of applications will be given in the field of medicine or liquid treatment.This work was supported in part by CNRS PEPS project ACUMULTIPLAS, by the ITMO Cancer in the frame of the Plan Cancer, project PLASCANCER N°17CP086-00, and by ARD2020 Cosmetosciences project PLASMACOSM. XD is supported by Thermo Fisher Sci. INEL/Région Centre Val de Loire PhD fellowship. AH is supported by ME NSR PhD fellowship.

International audience; In plasma medicine and agriculture reactive species produced by non-thermal plasmasources must play an important role. Many studies have been devoted on the effects of reactivespecies such as O, O21Δg, OH, N, NO and NO2 species just to name a few. So far, the CO moleculehas been overlooked.Carbon monoxide (CO) is well known for its toxic effects at high doses. The effects of COcan be quantified via the percentage of carboxyhemoglobin (COHb) it forms in the blood. Thepercentage of COHb in blood strongly depends on, not only the percentage of CO in air, but alsoon the exposure time. CO is however also naturally produced at cellular level, mostly via thecatabolism of heme. At low doses, CO has therapeutic properties. Experimental studies foundseveral positive effects of CO such as anti-inflammatory, vasodilatory and anti-apoptotic effects.It has also an influence on plants and promote the seed germination and increases the rootsformation [1].In this contribution, we will shortly review the reactivity of CO at the molecular level andits effects as a signaling molecule. It will be shown that CO triggers and competes with severalcellular receptors which are sensitive to the NO molecule as well.Many studies have demonstrated over the years that plasmas are able to produced CO from thedissociation of CO2 over a wide range of concentrations. Using glow discharges, dielectric barrierdischarges, nanosecond pulsed discharges or microwave plasmas, CO can be produced from ppmrange to several tens %. Plasmas are flexible sources allowing in situ production of CO andalleviate the risks related to its storage. Additionally, plasmas produce other components ofbiological relevance such as electric fields, heat, ultraviolet radiation, O, NO, NO2 and many otherreactive species. Synergic effects may therefore occur for the treatment of certain afflictions. Forinstance, it has been demonstrated that high doses of NO have a pro-inflammatory action [2] whileexogenous CO can down regulates its effects [3]. Plasmas with CO2 admixtures as a source of COseem then promising in applications such as wound healing and seed germination.References[1] E. Carbone and C. Douat, Plasma Medicine, 8(1):93–120 (2018).[2] Guzik TJ, Korbut R, Adamek-Guzik T. Nitric oxide and superoxide in inflammation and immuneregulation. J Physiol Pharmacol. 2003;54(4):469–87.[3] Ingi T, Cheng J, Ronnett G V. Carbon Monoxide: An Endogenous Modulator of the Nitric Oxide–CyclicGMP Signaling System. Neuron. 1996;16(4):835–42.

International audience; Single plasma jets have allowed significant advances in in vivo or directly on human experiments(e.g. [1], [2]). The results are particularly promising, but, ultimately, they couldbe limited in thefuture due to the fact that the treatment times are rather long due to the very small surface areatreated by the produced plasma. There is a real challenge to develop sources that allow treatmentover larger areas while remaining practical and at a reasonable cost. To this end, there arealready flexible or rigid surface DBDs but they require an extremely small distance between thereactor and the treated tissues, which limits their use in many situations (particularly when thetreated surfaces exhibit large variations in the surface morphology leading to points ofattachment of streamers and therefore to a very inhomogeneous treatment). "Ideal" sources aretherefore sources with the flexibility of a jet and treatment surfaces comparable to large DBDs. Itis in this spirit that we have developed a new generation of applicators based on a single PlasmaGun system and able to generate a multitude of jets (from tens up to few hundreds) fromtheprimary plasma jet, as shown in Fig. 1.Fig. 1: Multijet plasma source from single Plasma GunBefore proceeding to in vivo treatments, we qualified the sourcesthrough in vitro experiments ofdecontamination on colonies grown on agar plates in traditional Petri dishes, to check theequivalence of each of the jets generated, as well as on colonies grown onvery large agarsurfacesscanned with our system,to check large surface treatment feasibility. The results are extremelyencouraging and demonstrate the effectiveness of the multijet system, which allows both theprocessing of large-scale targets as well as the reductionof the processing times that otherwisecan be prohibitive with single-jet systems.We will present experimental results obtained on thegeneration of different types of multijets, as well as results obtained with one multijet plasmasource on the decontamination of multi-resistant bacterial colonies grown from hospital inpatientsamples.AcknowledgementsThis work was supported by the CNRS PEPS project ACUMULTIPLAS and the ITMO Cancerin the frame of the Plan Cancer, project N°17CP086-00.References[1] L. Brulé et al, Plos One 7, 0052653 (2012)[2] H R Metelmannet al, CPM, 9, 6(2018)

International audience; Over the past decade, there has been a growing interest in the development of cold atmosphericpressure plasmas for new biomedical applications. This so called Plasma Medicine concernsvarious clinical indications, including infectious diseases and recently, cancer treatment [1].Besides encouraging demonstrations, it has been shown that tolerance and safety issues should beconsidered with great care for any therapeutic application [2]. A new generation of applicators,able to generate multiple jets from a single primary plasma jet, has been developed and qualifiedthrough in vitro experiments. Moreover, they have shown multiple interests (cf. the presentation ofTh. Maho and colleagues in this conference).Using one of these multijet plasma sources, we have proceeded to in vivo treatments on healthymice skin. Various assays have been carried, on nude mice (hairless mice) and CBl57/6 mice (hairymice), which skins have different properties. The distance between the nozzle and the skin surfaceof the treated mouse can be adjusted by applying a spacer (in order to guarantee a constant gapduring treatment - spacer not shown). The presence or absence of skin damages caused by theplasma was assessed as a function of time, distance and delivered power.Fig. 1: Assays of multijet plasma source from single Plasma Gunon Nude mouse (left) and CBl57/6 mouse (right)Between the applicator and the target, plasma jets could appear either clearly separated from eachother or as a more diffuse discharge. Depending on the distance set between the nozzle and thetissue, different thermal effects and skin damages have been observed. The experimental resultsobtained from the characterization of these variables and their effects on the healthy mouse skinsurface will be presented. These promising results will be used as guidance for the application ofmultijet plasma on decontamination procedures (cf. the presentation of Th. Maho et al.).AcknowledgementsThis work was supported by the CNRS PEPS project ACUMULTIPLAS and the ITMO Cancer inthe frame of the Plan Cancer, project N°17CP086-00.References[1] M. Vandamme et al, Plasma Medicine 1(1): 27-43 (2011)[2] S. Kos et al, PLoS ONE 12(4), e0174966 (2017)

International audience; Atmospheric pressure plasma jets have demonstrated their ability in biomedical applications thanks to their low gas temperature and their capacity to produce radicals, ions, electrons, UV radiation and electric fields. However the understanding of the interactions between the plasma and living cells and tissues is still far from being completely understood. Recently, Robert et al characterized two components of the electric field from a plasma jet and showed that the latter can propagate deeply in tissues on several mm [1]. In this work, we focus on the study of the electric field induced by the plasma and its influence on the cell membrane. Propidium iodide, dextran sulfate and plasmid DNA are used to measure the permeability of the membrane, while an electro-optic probe is used to measure the longitudinal and the radial components of the electric field. The two components are both spatially and temporally resolved. To investigate the contribution of the electric field on the cell membrane, a dielectric barrier is used between the plasma and the biological target. A comparison with and without the barrier will be presented for both biological and agriculture applications. [1] E. Robert et al, 2015, Phys. Plasmas 22 122007

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International audience; The study of plasma jets operating in free jet mode and on conductive targets relevant for biomedical applications is discussed. The simultaneous diagnostics of helium metastable through laser absorption, electric field (EF) with an electro-optic probe and current appears as a unique approach to get deep insights on the mechanisms triggered when primary ionization wave (IW), driving the plasma jet propagation, impacts the target. Secondary IWs, back and forth travelling from the plasma jet powered electrode and the grounded target, is measured and may result, depending on the operating parameters of the device, in the transition to a glow like discharge. In such situation, huge enhancement of reactive species production is triggered in connection with significant increase of current flowing through the target. This study allow for a better analysis of the plasma jet delivery on target relevant for biomedical applications and open up opportunities to control reactive species concentration and current amplitude in such experiments. These experimental results are in good agreement with modeling work recently published by group of M.J. Kushner (University of Michigan) on the plasma jet touching or not targets of various natures. The second aspect of the study deals with the characterization of both the amplitude and the topology of the transient EF generated in the vicinity of the plasma jets. Time resolved longitudinal and radial EF, with respect to the jet propagation axis, having amplitudes ranging from a few to a few tens of kV/cm have been measured. There also a good agreement is achieved with modeling data from the group of A. Bourdon (LPP laboratory) which allow extending this diagnostics to region where experimental analysis is hard or disturbing with our probe. It is probably worth considering such intense EF with respect to their potential impact on biological samples.

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International audience; In this work we present Schlieren images of a Plasma Gun discharge fed not only with helium but also for the first time with neon and argon buffers. It is demonstrated that efficient gas flow channelling is observed with operation of the PG with any of the three gases. Such gas flow channelling is also proven to be dependent on voltage polarity and frequency. Analysis of the role of molecular admixtures (N2 or O2) confirms the non-thermal nature of the effect and the potential crucial role of large negative ions.

International audience; He (23S) helium metastable is a key state in the energetic transfers occurring in atmospheric pressure plasma jets now widely used for applications related to biology or material processing. Its measurement mainly relies on laser absorption which is not always easy to perform. In this work, we show that a simple way to follow the time evolution of this state can be found in the late time evolution of the transitions emitted from the N2+B state which is mainly populated by Penning ionisation from He (23S).

International audience; In this preliminary work, we showed that a kHz plasma jet can induce cell membrane permeabilization. Those results have been compared to electropermeabilization and indicate that permeabilization by plasma is less efficient, which is probably due to the fact that in electropermeabilization a current gets through the cells. We also showed that chemistry and/or electric field induced by plasma plays a role in cell permeabilization.

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International audience; Compelling evidence suggests that Cold Atmospheric Pressure Plasma (CAPPs) has potential as a new cancer therapy. However, knowledge about cellular signaling events and toxicity subsequent to plasma treatment of is still poorly documented. The aim of this study was to focus on the interaction between 3 different types of plasma (He, He-O2, He-N2) and human epithelial cell lines to gain better insight into plasma-cell interaction. We choose epithelial cell lines (human keratinocytes, human fibroblasts, human colorectal carcinoma and skin melanoma) to gain insight into plasma-cell interaction and to determine which cellular pathways are induced by CAPP treatment in normal and malignant cells. We provide evidence that the proteasome, a major intracellular proteolytic system which is important for tumor cell growth and survival, is a target for (He or He-N2) CAPP. This is accompanied by apoptosis, DNA damage, mitochondrial dysfunction and mild oxidative protein damage. By differential label-free quantitative proteomic analysis we found that CAPP triggers antioxidant and cellular defense but also seen cancerous processes in keratinocytes. Moreover we found that malignant cells are more resistant to CAPP treatment than normal cells. However, reactiveoxygen and nitrogen species (RONS) are not the only actors involved in cell death; electric field and charged particles could play a significant role especially for He-O2 CAPP. Particular attention was paid to the contribution of the electric field (EF) and RONS in cellular response to plasma treatment. Taken together, our findings provide insight into potential mechanisms of CAPP-induced cell death.

International audience; Cold atmospheric pressure plasmas have demonstrated their ability in biomedical applications thanks to their low gas temperature and their capacity to produce radicals, ions, electrons, UV radiation and electric field. However, the understanding of the interactions between plasma, living cells and tissues is still far from being completely understood. Several studies have shown that plasma could be used to enhance cell permeabilization to deliver chemotherapy [1] or nucleic acids [2].In this work, we investigated the parameters needed for helium plasma to induce a cell membrane permeabilization on cancerous cells for drug delivery purposes. Using our optimal settings, different fluorescent molecular markers were used in order to determine pore size, opening kinetics and the importance of endocytosis in the process. We were able to deliver propidium iodide in almost 30% of HeLa cells 30 minutes after plasma treatment generated at 14kV, a frequency of 100Hz during 100s using 0.5slm of helium. No significant cytotoxicity was measured 24h after treatment. Efficient drug delivery was obtained using molecules up to 70kDa (figure 1). Experiments using plasma activated media were done to understand the contribution of radical formation on cell membrane permeabilization. The influence of plasma-generated electric field has also been investigated. For this purpose, a dielectric barrier was used between the plasma and the biological target. A comparison with and without the barrier will be presented for biological application. In conclusion drug delivery using plasma is dependent of the electric field, endocytosis and plasma-induced chemistry. Figure 1. Fluorescence microscopy of HeLa cells 30 minutes after treatment by helium plasma in the presence of propidium iodide, 70kDa FITC-Dextran or 150kDa FITC-Dextran.References[1] W. Zhu, et al., Scientific Report, 6, 21974 (2016).[2] M. Jinno, et al., Arch. Biochem. Biophys, 605, 59 (2016).

International audience; Among the many diverse applications of non-thermal atmospheric pressure plasmas (NTAPP), the treatment of liquids has recently drawn a lot of attention, especially for organic pollutant degradation [1]. There are number of possibilities to apply the NTAPP on/in the liquid reported in the literature. In this work, we report on the use of plasma plume produced by a Plasma Gun directed immersed in the solution to be treated. In this case, the plasma is directly produced in the liquid volume without any electrode in contact with the solution.In this work, the plasma is generated with the baseline Plasma Gun [2] setup with a thin diameter (180 μm inner diameter) flexible silicone capillary immersed in a liquid sample and flushed with small rare gas flow rate. A Neon plasma was used with a gas flux of 12,4 sccm, the positive polarity pulse repetition rate was 2 kHz, the silicone capillary of the Plasma Gun is immersed in a quartz tank allowing for absorption spectroscopy measurement during plasma treatment. As a first assessment of plasma in liquid delivery, we investigated the impact of a pulsed atmospheric plasma streams (PAPS) [2] in acetone solutions.Figure 1 represents the spectral absorption of a water solution containing 1000 ppm of acetone, without treatment and for various plasma treatment times. A time dependent evolution of the absorption spectrum over the range from 200 to 400 nm is measured. As we can see, the plasma changes the spectral absorption mainly in the wavelength domain of 280 to 360 nm. Control experiment with only the gas flow applied in the liquid solution verifies that then no change in the absorption spectrum is observed. Most of the changes we observed with plasma where between 280 and 360 even for higher concentration of acetone, but not for pure acetone. This indicates that reactive species generated in the water buffer probably play a critical role in the pollutant chemical degradation. By-products of the liquid solution plasma treatment have not so far been analyzed.[1] E. Marotta et al, Plasma.Proc.Polym 8 867–75.[2] E. Robert et al, Plasma Sources Sci. Technol. 21 (2012) 034017 (12pp)Fig. 1. Absorption profiles for a water/1000 ppm acetone solution treated by Plasma Gun for various treatment times in comparison with not treated solution.

International audience; The use of cold atmospheric pressure plasma jets for in vivotreatments implies most of the time plasma interaction with conductive targets. The effect of conductive target contact on the discharge behavior is here studied for a grounded metallic target and compared to the free jet configuration. In this work, realized with a Plasma Gun, we measured helium metastable HeM (23S1) concentration (by laser absorption spectroscopy) and electric field (EF) longitudinal and radial components (by electro-optic probe). Both diagnostics were temporally and spatially resolved. Mechanisms after ionization front impact on target surface have been identified. The remnant conductive ionized channel behind the ionization front electrically transiently connects the inner high voltage electrode to the target. Due to impedance mismatching between ionized channel and target, a secondary ionization front is initiated and rapidly propagates from the target surface to the inner electrode through this ionized channel. This leads to a greatly enhance HeM production inside the plasma plume and the capillary. Forward and reverse dynamics occur with further multi reflections of more or less damped ionization fronts between the inner electrode and the target as long as ionized channel is persisting. This phenomenon is very sensitive to parameters such as target distance and ionized channel conductivity affecting electrical coupling between these two andevidenced using positive or negative voltage polarity and nitrogen admixture. In typical operating condition for the plasma gun used in this work, it has been found that after the secondary ionization front propagation, when the ionized channel is conductive enough, a glow like discharge occurs with strong conduction current. HeM production and all species excitation, especially reactive ones, are then driven by high voltage pulse evolution. The control of forward and reverse dynamics, impacting on the production of the glow like discharge, will be useful for biomedical applications on living tissues.

International audience

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International audience; Atmospheric pressure plasma jets are non-thermal plasmas and have the ability to create reactive species. These features make it a very attractive tool for biomedi-cal applications. In this work, we studied NO and N 2 O production, which are two species having biomedical properties. NO plays a role in the vascularization and in ulcer treatment, while N 2 O is used as anesthetic and analgesic gas. In this study, the plasma source is similar to the COST Reference Microplasma Jet (–APPJ). Helium is used as feed gas with small admixtures of molecular nitrogen and oxygen of below 1%. The absolute densities of NO and N 2 O were measured in the effluent of an atmospheric pressure RF plasma jet by means of ex-situ quantum-cascade laser absorption spectroscopy via a multi-pass cell in Herriot configuration. We will show that the species' production is dependent on several parameters such as power, flow and oxygen and nitrogen admixture. The NO and N 2 O densities are strongly dependent on the N 2-O 2 ratio. Changing this ratio allows for choosing between a NO-rich or a N 2 O-rich regime [1]. [1] Douat et al, PSST, 25 (2016) 025027

International audience

International audience; In the last decade, plasma jets generated in ambient air at room temperature have found an impressive number of material processing and biomedical applications [1, 2]. While being generated in simple discharge reactors, dielectric barrier discharge or miniaturized plasma torch, it has been rapidly evidenced that their reliable operation and diagnostics was quite challenging and strongly application dependent. In this invited lecture, we will emphasize on the necessity and benefit first to perform plasma diagnostics not only in situation of free jet expansion but more informatively with including target used or mimicking those involved for plasma jet in operation for any dedicated application. It is also crucial to perform combined diagnostics to entangle the number and cross correlated physico chemical phenomena inherent with plasma jet delivery. Recent measurements including gas flow diagnostics with or without plasma operation through Schlieren visualization, species density assessment with IR laser absorption or laser induced fluorescence techniques [3], plasma propagation dynamics and emission diagnostics with fast, eventually wavelength filtered, ICCD imaging, but also electric field measurements [4] will be presented. The necessity to combine various experimental data but also the confrontation with simulation results [5] will be enlighten in the diagnostics of electric fields, radical generation over surface, helium metastable generation and discharge propagation and counter propagation on metallic targets. AcknowledgmentsX.D. is supported through a Région Centre Val de Loire/INEL PhD fellowship.References[1]Penkov O.V. et al, J. Coat. Technol. Res., 12 (2), 225-23 (2015)[2]Laroussi M , IEEE Trans. Plas.Sci., 43 (3), 703-712 (2015)[3]Ries D. et al, J. Phys. D: Appl. Phys. 47 275401 (2014)[4]Robert E. et al, Phys. Plasmas, 22, 122,007 (2015)[5]Bourdon A. et al, accepted PSST (2016)