Cold Atmospheric Plasma Jet Research Articles

Experimental Studies on Physicochemical Parameters of Water Samples before and after Treatment with a Cold Atmospheric Plasma Jet and its Optical Characterization

Cold plasma-liquid interaction becomes a growing interdisciplinary area of research involving plasma physics, fluid science, and chemistry. Plasma-liquid interaction has gained more interest over the last many years due to its potential applications in different fields. Cold atmospheric plasma jet is an emerging technology for surface drinking water treatment to improve quality and surface modification that is chemical-free and eco-friendly. Cold plasma treatment of water samples results in changes in turbidity, pH, and conductivity and in the formation of reactive oxygen and nitrogen species (RONS). As a result, plasma-activated water has a different chemical composition than water and can serve as an alternative technique for microbial disinfection. CAPJ has been generated by a high voltage 5 kV and a high frequency 19.56 kHz power supply. The discharge has been characterized by an optical method. To characterize the cold atmospheric pressure argon plasma jet, discharge plume temperature, and electron rotational and vibrational temperature have been determined. Cold atmospheric argon plasma jet produced at atmospheric condition contains high energetic electrons, ions, UV radiation, reactive oxygen, and nitrogen species named as cold plasma which has a wide range of applications in the biomedical industry, as well as in water treatment. Nowadays, researches have been carried out on ozonation through plasma jet interaction with surface drinking water. In this paper, we compare the change in physical and chemical parameters of surface water used for drinking purposes. The significant change in the physical parameters such as pH, turbidity, and electrical conductivity was studied. In addition, the significant changes in the concentration and absorbance of nitrate, ferrous, and chromium ions with respect to treatment time were studied. Our results showed that plasma jet interaction with surface drinking water samples can be useful for the improvement of water quality and an indicator for which reactive species play an important role in plasma sterilization.

Enhancement Propagation of Protocorms in Orchid (Cymbidium tracyanum L. Castle) by Cold Atmospheric Pressure Air Plasma Jet

Propagation of orchid (Cymbidium tracyanum L. Castle) treated by using an air cold atmospheric pressure plasma jet at room temperature was investigated. The peak-to-peak voltage discharge and flow rate of the air atmospheric pressure plasma jet were set at 10.5 kV and 10 L/min, respectively. The constituent particles of the air cold atmospheric pressure plasma jet were revealed by optical emission spectroscopy. At the end of the jet nozzle, the constituent particles were observed, such as hydroxyl radical ˙OH, N2 first negative system (N2 1 −), N2s positive system (N2 2 +), and atomic oxygen. The average size, average number of buds, fresh and dry weights simultaneously increased by cold air plasma treatment compared with the control ones. The highest positive effects of treated protocorms on average size, average number of buds, fresh and dry weight were significantly improved by 238.2, 475.9, 85.6, and 152.5%, respectively. The transmission electron microscope showed the cytoplasmic cell wall in orchid protocorm disturbed by air cold plasma. Thus, the effects of constituent particles of air plasma might attack in the cell wall of protocorm leading to cell loosening, which improved elongation and released bud dormancy. These results indicated that the propagation of orchid protocorms depended on the effects of air cold plasma treatment with different plasma time durations.

Impact of Short Time Atmospheric Plasma Treatment on Onion Seeds

The paper presents the results of an experiment on the effect of cold plasma (He + O2 and He + Air) generated in a radio frequency cold atmospheric plasma jet on the process of germination of onion cv. Wolska (Allium cepa L.) seeds. In order to determine the impact of the gas flow on the seed surface, CFD simulations and Schlieren imaging were performed and surface characteristics were studied using a digital microscope. Plasma treatment of the seeds was carried out four times (2, 5, 10 and 15 s) with one control group. Pre-sowing plasma stimulation of seeds improved the germination capacity and germination energy for all tested groups in comparison to the control. The best germination capacity and energy were obtained for seeds stimulated with 10 s of plasma treatment. Analysis of the data showed a statistically significant impact of plasma treatment on the onion seed’s germination parameters. Plasma treatment did not induce significant changes on the seed surface, as microscope images showed but length of all plasma-treated seedlings increased in comparison to control.

Accelerated Healing of Chronic Wounds under a Combinatorial Therapeutic Regimen Based on Cold Atmospheric Plasma Jet Using Contact and Noncontact Styles

Accelerated Healing of Chronic Wounds under a Combinatorial Therapeutic Regimen Based on Cold Atmospheric Plasma Jet Using Contact and Noncontact Styles

The Potential Use of a Cold Atmospheric Plasma Jet for Decontamination of Hospital Surfaces. A Pilot Study

The Potential Use of a Cold Atmospheric Plasma Jet for Decontamination of Hospital Surfaces. A Pilot Study

Analysis of Grounded Substrate Effects on Cold Atmospheric Plasma Jet Irradiation of Cellular and Animal models

Plasma devices with cylindrical and plane geometries generating the nonthermal atmospheric plasma jets are used for the treatment of the cancer cells in vitro and in vivo. It is shown in the simulations and experiment that the grounded substrate placed under the bio target essentially increases the plasma treatment efficiency. Nevertheless the temperature control is needed to avoid the burns in a spot of contact of plasma jet with the mice skin. The measured and calculated local temperature increase with different regimes of plasma device operation is presented. The MTT and iCELLigence assays of the viability of cancer cells in vitro show the efficiency of plasma jet treatment and mice models in vivo demonstrate the safety regime for cold atmospheric pressure plasma irradiation.

Fast approximate learning-based multistage nonlinear model predictive control using Gaussian processes and deep neural networks

Scenario-based model predictive control (MPC) methods introduce recourse into optimal control and can thus reduce the conservativeness inherent to open-loop robust MPC. However, the uncertainty scenarios are often generated offline using worst-case uncertainty bounds quantified a priori, limiting the potential gains in control performance. This paper presents a learning-based multistage MPC (msMPC) for systems with hard-to-model dynamics and time-varying plant-model mismatch. Gaussian Processes (GP) are used to learn state- and input-dependent plant-model mismatch in real-time and accordingly adapt the scenario tree online. Due to the increased computational complexity associated with incorporating the GP predictions into the optimal control problem, the learning-based msMPC (LB-msMPC) law is approximated by a deep neural network (DNN) that is cheap-to-evaluate online and has a small memory footprint, which makes it suitable for embedded applications. In addition, we present a novel algorithm for training the DNN-based controller that uses a GP description of the plant-model mismatch to generate closed-loop simulation data, which ensures the LB-msMPC law is evaluated in regions of the state space most relevant to closed-loop operation. The proposed LB-msMPC strategy is demonstrated on a cold atmospheric plasma jet with applications in (bio)materials processing. The simulation results indicate the promise of the approximate LB-msMPC strategy for control of hard-to-model systems with fast dynamics on millisecond timescales.

Cold atmospheric plasma jet applied for TiO2/carbon fiber composite biomaterial

AbstractIn the present work, Titanium dioxide (TiO2) micro–nanostructured thin films are deposited by a cold atmospheric plasma jet on carbon fiber substrates. The surface morphology, grain size, and structure phase of TiO2 thin films are investigated by scanning electron microscopic (SEM), X-ray diffraction (XRD), and Raman spectrum. As the discharge voltage increased from 5 to 15 kV, the size of these TiO2 particles decreased from 2 to 3 μm to less than 1 μm. The XRD and Raman spectroscopic results show TiO2 on the carbon fiber surface prepared by atmospheric plasma jet is at the mixture phase of anatase and rutile. We also investigated the adhesion and proliferation assays of MC3T3-E1 preosteoblasts on the samples. The surface with smaller TiO2 particles deposited on carbon fiber is more appropriate for attachment of preosteoblasts. Furthermore, the highest proliferation of MC3T3-E1 was found on a sample with smaller TiO2 particles after incubation. Our data suggest that the increased roughness fosters cell attachment and proliferation on the surface of TiO2/carbon fibers.

INNV-13. SYNERGISTIC EFFECT OF COLD ATMOSPHERIC PLASMA IN COMBINATION WITH TEMOZOLOMIDE TO TREAT GLIOBLASTOMA IN A NON-INVASIVE MOUSE XENOGRAFT MODEL

Abstract INTRODUCTION A primary limitation in anti-cancer therapy is the resistance of cancer cells to chemotherapeutic drugs. However, combination therapy may be an effective approach for reducing drug derived toxicity and evading drug resistance, resulting in improved clinical treatment of cancer. Our prior work demonstrated effective treatment of glioblastoma (GBM) with cold atmospheric plasma (CAP) technology with minimal effect to normal cells. Consequently, CAP may serve as a strong candidate for combination therapy with the classical antineoplastic alkylating agent Temozolomide (TMZ) to treat GBM. OBJECTIVES To determine the in vivo co-efficacy of CAP and TMZ to “sensitize” GBM. METHODS An in vivo study was performed using the CAP jet device (He-gas) to determine the effect of combined CAP–TMZ treatment. U87MG-luc glioblastoma cells were implanted intracranially in athymic nude NU(NCr)-Foxn1nu/immunodeficient mice. He-CAP (or control He alone) was non-invasively applied over the skin for 60sec to developed tumors on the first day of the treatment followed with 6.5 mg/kg TMZ or vehicle control treatment for 5 days for two weeks (n=5/group). In vivo bioluminescence imaging was used to monitor tumor volume on the 6th, 9th and 13th treatment day. RESULTS In vivo bioluminescence imaging revealed a marked 8.0±3.2 fold increase in tumor volume in control animals (He-vehicle). Treatment with He-TMZ (6.7±2.5 fold) or CAP-vehicle (4.8±1.7 fold) in isolation had minimal effect in preventing tumor growth. However, combined CAP-TMZ co-treatment virtually prevented increases in tumor volume over 2 weeks (1.8±0.2 fold). CONCLUSIONS Collectively, these findings indicate an effective synergistic treatment method for GBM combining CAP with TMZ. Future investigations look to incorporate radiation into the treatment regimen as well as primary GBM cell models.

On cold atmospheric-pressure plasma jet induced DNA damage in cells

To investigate the potential role of the hydroxyl radical (•OH) in cold atmospheric plasma (CAP) jet treatment, two fluorescence-based methodologies are utilised to measure DNA strand breaks. The first comprises a model system of a double-stranded DNA oligomer, where the respective strand ends are tagged with fluorophore and quencher molecules; and the second, a cell culture system reporting DNA strand breaks using the γ-H2AX assay. During the various CAP jet treatments, optical emission spectroscopy is used to detect the •OH in the gas phase and electron spin resonance is used to detect the •OH in solution. The CAP jet production of the •OH is shown to correlate to CAP jet induced DNA damage both with the DNA model and in biological cells. Results indicate that the CAP jet induces a higher degree of DNA damage when the CAP plume is in contact with the target solution. The potential of a ‘plasma screen’ based upon a hydrogel film, as a method to remove the DNA-damaging •OH species from reaching skin cells, is shown to significantly reduce DNA damage whilst facilitating the delivery of hydrogen peroxide. These findings could aid in the development of CAP jet-based applications where DNA damage is the objective (e.g. in cancer treatment) and others where it is to be avoided, e.g. in open-wound treatment and dermatology.

Cold atmospheric single plasma jet for RONS delivery on large biological surfaces

Several attempts have been made to deliver reactive oxygen and nitrogen species (RONS) produced by non-thermal plasma onto large surfaces in a controllable way compatible with skin treatments. In this paper, the effect of pulse frequency, in the range 0.5–20 kHz, on the discharge behavior was studied on skin tissue models to evaluate potential treatment changes. This has been done through electrical characterization, visualization of the helium flow (by Schlieren technique), produced plasma jet modifications (ICCD imaging) and RONS measurements. The results show that, in addition to its well known important role in the production of the chemical species, the applied discharge frequency plays a very significant role in the size of the treated surface. An enhancement of NO*, OH* and O* production in the gas phase at the higher frequency is reported and assigned to the stronger mixing of the helium flow with ambient air. The efficacy of plasma jet on transporting RONS on/into agarose gel and pig skin has been evaluated. The distribution of the reactive species on the target, or passing through, is strongly dependent on the discharge frequency and consequently induces pH variations. The present study supports a new way for enlarging the treated surface by using a simple jet at high frequency in the 20 kHz range, leading, with appropriate gas flow and distance to target, to conditions of RONS production that are compatible with potential uses for biomedical or cosmetic applications.

Non-Thermal Plasma Application in Tumor-Bearing Mice Induces Increase of Serum HMGB1.

The application of cold atmospheric plasma (CAP) in cancer therapy could be one of the new anticancer strategies. In the current work, we used cold atmospheric plasma jet for the treatment of cultured cells and mice. We showed that CAP induced the death of MX−7 mouse rhabdomyosarcoma cells with the hallmarks of immunogenic cell death (ICD): calreticulin and heat shock protein 70 (HSP70) externalization and high-mobility group box 1 protein (HMGB1) release. The intensity of HMGB1 release after the CAP treatment correlated directly with the basal extracellular HMGB1 level. Releasing from dying cells, HMGB1 can act as a proinflammatory cytokine. Our in vivo study demonstrated that cold atmospheric plasma induces a short-term two-times increase in serum HMGB1 level only in tumor-bearing mice with no effect in healthy mice. These findings support our hypothesis that CAP-dependent HMGB1 release from dying cancer cells can change the serum HMGB1 level. At the same time, we showed a weak cytokine response to CAP irradiation in healthy mice that can characterize CAP as an immune-safety physical antitumor approach.

Helium/Argon-Generated Cold Atmospheric Plasma Facilitates Cutaneous Wound Healing.

Cold atmospheric plasma jet (CAPJ) or non-thermal plasma jet has been employed in various biomedical applications based on their functions in bactericidal activity and wound healing. However, the effect of CAPJ generated by a particular composition of gases on wound closure and the underlying mechanisms that regulate wound healing signals remain elusive. In the present study, we investigated the impact of helium (He)- or a gas mixture of He and argon (He/Ar)-generated CAPJ on cell proliferation, which is a pivotal step during the wound healing process. With careful treatment duration control, He/Ar-CAPJ effectively induced keratinocyte proliferation and migration mediated through the activation of epithelial-to-mesenchymal transition (EMT) and cell cycle progression, which was evidenced by a decrease in E-cadherin levels and increases in N-cadherin, cyclin D1, Ki-67, Cdk2, and p-ERK levels. Rat wound healing studies showed that He/Ar-CAPJ treatment facilitated granulation tissue formation and mitigated inflammation in cutaneous tissue, resulting in accelerated wound closure. These findings highlight the possibility that He/Ar-CAPJ can be developed as a therapeutic agent for enhancing wound healing.

Inactivation efficacy and mechanisms of plasma activated water on bacteria in planktonic state.

The study aimed to investigate the inactivation efficacy and mechanisms of plasma activated water (PAW) on selected bacteria in planktonic state. Plasma activated water was generated using an atmospheric cold plasma jet at 15, 22 and 30kV for 5min. Escherichia coli, Listeria innocua, Staphylococcus aureus, Aeromonas hydrophila, Pseudomonas fluorescens and Shewanella putrefaciens were selected as the representative bacterial species. Each bacterial suspension was inoculated into PAW immediately after generation, and the viable counts at different exposure times of 0·5, 1, 3, 5 and 24h during 4°C storage were measured to determine the inactivation efficacy. Scanning electron microscopy images of the bacteria were conducted to examine the structural changes. Physicochemical properties of PAW, including pH, conductivity, oxidation reduction potential (ORP), and reactive species of H2 O2 , NO2 - and NO3 - were measured. The results demonstrated that inactivation efficacy was in positive correlation with voltage and exposure time. Gram-negative bacteria were more susceptible to PAW than Gram-positive bacteria. Morphology damage was observed for all the bacterial species. PAW was significantly acidified, conductivity and ORP were significantly increased, and reactive species were detectable after 48h. This study offered a better understanding of the inactivation mechanisms of PAW, and the inactivation efficacy can be affected by voltage, exposure time and bacterial species. This study demonstrated the potential usage of PAW as an alternative disinfectant.

Introducing adaptive cold atmospheric plasma: The perspective of adaptive cold plasma cancer treatments based on real-time electrochemical impedance spectroscopy

Following the understanding of the cold atmospheric plasma jet control, the optimization of plasma parameters for biomedical applications has become an important area of research in the field of plasma-based cancer treatment. A real-time feedback signal is usually required by a control algorithm, such as a self-adaptive plasma jet, which is designed to automatically self-optimize its parameters to adapt to a variety of biomedical applications and situations. In this paper, we introduce the potential of replacing the cell viability or cell stress assay with electrochemical impedance spectroscopy (EIS) to provide a real-time feedback signal for a model predictive control (MPC) method aided by machine learning. The EIS frequency is in the kHz to GHz regime. Therefore, the MPC method is not only designed for minimizing the cancer cell viability, but also considered to optimize cell membrane behaviors and other chemical species dialing. Since these signals are in the range of GHz, we introduce alternatives for the impedance analyzer to measure the impedance spectrum, including a Fabry–Pérot resonator and one of its scanning-array variations.

Evaluation of the anticancer effects induced by cold atmospheric plasma on leukemia stem cells

The application of cold atmospheric plasma (CAP) in cancer treatment has received extensive attention. However, little research was observed on the anticancer effects of CAP to tumor stem cells. Here, we analyzed the discharge characteristics of a CAP jet and plasma-induced effects on acute myeloid leukemia (AML) stem cells. Our results showed that the most active particles can be produced when helium is doped with 0.5% oxygen and the jet device is driven by a pulsed power supply. And when using this plasma jet device to treat acute myeloid leukemia (AML) stem cells, it is found that CAP jet can effectively inhibit the cell activity of AML stem cells, which provides new ideas for the treatment of AML.

Measuring the air fraction and the gas temperature in non-thermal argon plasma jets through the study of the air influence on the collisional broadening of some argon atomic emission lines

Cold atmospheric argon plasma jets have shown to be very promising in medicine and they are being currently used for therapeutical uses such as the healing of wounds or the treatment of tumors. Because they run in the open atmosphere, they generate copious amounts of reactive oxygen and nitrogen species, which play an outstanding role in their biological action. But, in this kind of reactor, unknown amounts of air enter the plasma region depending on the experimental conditions, changing the chemistry in them, and eventually their effects. In this work, we propose a new spectroscopic method to measure the amount of air in argon non-thermal (including cold atmospheric) plasma jets through the collisional broadening of Ar I 840.86 and Ar I 842.46 nm emission lines. The method allows the simultaneous determination of the gas temperature. For validation purposes, it was applied to a microwave-induced plasma jet working at different operational conditions. Results were consistent with those obtained from the rotational temperature derived from simulations of N2 (2nd positive system) rovibrational band.

Modelling of turbulent reacting flow for a cold atmospheric pressure argon plasma jet

A two-dimensional, axisymmetric model of turbulent reacting flow for a cold atmospheric pressure argon plasma jet has been developed. The model is formulated within the framework of boundary-layer theory and allows to study the transport and chemical processes in the jet with low computational effort. The generation of primary reactive gas species is described using a local zero-dimensional reaction kinetics model. The proposed modelling approach is validated against available experimental data. The computations are performed for a turbulent cold plasma jet operated in argon with admixtures of oxygen, air and water. The effect of a shielding gas on the transport and chemical processes is discussed. The modelling results are compared with the results of quantitative schlieren diagnostics (for Ar), molecular-beam mass spectrometry (for Ar, N2, O2), laser-induced fluorescence (for NO), two-photon absorption laser-induced fluorescence (for O), ultraviolet absorption (for O3) and cavity ring-down (for HO2) spectroscopy measurements. It is shown that turbulent diffusion across the jet is an important factor influencing the behaviour of reactive species that are of interest for practical applications.

Selective treatments of prostate tumor cells with a cold atmospheric plasma jet

Background: Low temperature plasma is an ionised gas generated at atmospheric pressure with the temperature of heavy particles (ions, molecules, atoms) close to room temperature. Recent progress highlighted the efficiency of plasma to induce cell death in many cancer cell lines. In the current context of the emergence of the use of cold plasma for medical purposes, this article aims to study the effect of a cold plasma of helium on ex-vivo prostate cells.Methods: A cold atmospheric plasma torch was developed to treat different tumor cells. Parameters like electric voltage, gas flow, cell/torch distance, and exposure time were studied to improve the effects of plasma onto two human prostate tumor cells lines, with different metastatic potential, LNCaP and PC3 and then, compared to human prostate epithelial cells P69. The plasma torch operated by a voltage up to 10 kV, without any risk of arcing, exhibited a visible plasma plume up to about 70 mm, with a temperature close to room temperature. The induced temperature rise due to the plasma treatment is measured to ensure that observed results are not thermal effects. After plasma treatment, microscopy and MTT analyses are achieved to measure cells viability. An ordinary one-way ANOVA test were used between two groups with p-value less than 0.05.Results: An optimized protocol leads to the tumor cells death with regard to cell viability. Cold plasma treatment exhibits differential effect, regarding tumor status of cells without any significant influence of thermal effect (temperature increases of only few degrees Celcius above room temperature). The results show that non-tumor cells P69 are less sensitive to cold plasma exposure with a cell viability of 67% after 120 s of treatment, compared to tumor cell lines LNCaP and PC3, respectively at cell viability of 29% and 23% for the same treatment time.Conclusion: The cold helium plasma treatment showed a selective effect on prostate cells, with an enhanced apoptosis way for tumor cells, whereas the healthy cells are more resistant to the treatment. Moreover, during the treatment, the surface temperature rises only few degrees Celcius. This result is very promising for future in-vivo treatments.

Generation of cold atmospheric plasma jet by a coaxial double dielectric barrier reactor

In this study, the generation of cold atmospheric plasma jet was investigated in a coaxial double dielectric barrier configuration conjugated with a microsecond voltage pulse generator. The advanced reactor comprised two coaxial dielectric tubes of different diameters with two ring-shaped electrodes covering outside the larger tube. The electrodes were immersed in a liquid dielectric (i.e. transformer oil) in order to isolate them from the ambient air, which completely prevented the direct sparks formation between them within the investigated range of the applied voltage. The He discharge gas was fed to the inner tube while either air, N2, or O2 as a shielding gas was introduced into the gap between the two dielectrics. The result revealed that with these shielding gases, the unwanted abnormal discharge in the inter-dielectric gap was extinguished and the plasma discharge occurred only in the He gas in the inner tube. Consequently, the electrical power delivered to the He discharges maintained at a level of around 1 W with a considerable variation in the applied voltage. Meanwhile, the discharge power of the unshielded jet was almost tripled as the applied voltage was increased from 7 to 10 kV. Interestingly, the cold plasma jet generated by the alternative reactor design in this study, which had the electron density up to 2.5 × 1013 cm−3, consumed relatively less He gas with less restriction on the high voltage range applied. The design also enhanced the possibility to control the plasma chemistry and jet temperature by changing the shielding gas. Therefore, the reactor is capable of producing a cold atmospheric plasma jet for the emerging plasma application such as plasma medicine and bio-applications.