Non-thermal Atmospheric Pressure Plasma Research Articles

Insight into the generation network of reactive oxygen species in H2O under nonthermal atmospheric-pressure plasma irradiation using a kinetic modeling approach

A kinetic model incorporating the dominant generation networks of reactive oxygen species (ROS) in H2O under nonthermal atmospheric-pressure plasma irradiation was developed in this study. In the proposed model, the minimum necessary elementary reactions involving ROS were considered based on the behaviors of the dissolved O2 and H2O2 observed in plasma-irradiated H2O. The ROS included not only OH radicals but also other ROSs such as OOH, O, and these anionic radicals. The model agrees well with the experimental results for various initial dissolved O2 concentrations, pH values, and input power conditions. Further, the model could predict specific behavior under extrapolated conditions, which are in the presence of H2O2 at the initial conditions. In addition, the reaction rates of elementary reactions involving dissolved O2, which are difficult to measure in the experiments, were simulated by the model. It was found that the reaction rates between the consumption and production reactions of dissolved O2 were balanced at later stages of nonthermal atmospheric-pressure plasma irradiation. The model is expected to provide fundamental guidelines for the effective utilization of nonthermal atmospheric-pressure plasma irradiation.

Non-Thermal Atmospheric Pressure Plasma as an Adjunct to Intestinal Anastomosis: A Pilot Study on Preventing Anastomotic Leaks

Anastomotic leaks remain a significant challenge in intestinal surgery, often leading to severe complications. This study investigated a novel approach to enhance anastomotic healing and reduce the risk of leaks by combining traditional suturing and stapling techniques with non-thermal atmospheric pressure plasma (NTAPP) application. NTAPP, a cold atmospheric plasma generated through the ionization of ambient air, has been shown to possess antimicrobial, hemostatic, and wound-healing properties. NTAPP promotes sterilization, coagulation, and tissue regeneration by generating reactive oxygen and nitrogen species, potentially strengthening anastomotic union. This pilot study evaluated the efficacy of NTAPP in three patients undergoing intestinal anastomosis. Following the standard surgical procedure, NTAPP was applied directly to the anastomotic site. Postoperative outcomes were monitored for six months, including anastomotic leaks and healing rates. Preliminary results demonstrated promising outcomes. All three patients exhibited successful sealing of the anastomosis, with no evidence of leakage during the follow-up period, providing reassurance and confidence in the potential of sutures, staples, and NTAPP. These findings suggest that NTAPP can significantly improve the safety and efficacy of intestinal surgeries by reducing the incidence of anastomotic leaks. While further research with a larger sample is necessary to confirm these initial findings, the results of this study provide a strong foundation for exploring the potential of NTAPP as a valuable adjunct to conventional surgical techniques for preventing anastomotic leaks. This innovative approach could reduce postoperative complications, improve patient outcomes, and enhance the overall quality of care in intestinal surgery.

High-Speed Removal Process for Organic Polymers by Non-Thermal Atmospheric-Pressure Spark Discharge at Room Temperature and Its Mechanism

Heel marks (HMs) are a type of dirt stain consisting of polyester-based urethane rubber on polyvinyl chloride (PVC) floor surfaces. The rapid removal of HMs was achieved by using non-thermal atmospheric-pressure plasma technology. Mimetic HMs were prepared by coating PVC floor samples with HMs to a thickness of 13.9 μm. The removal area, thickness, and volume were measured after applying spark discharges at high voltage and a repetition rate of 50 kHz. The treated surfaces were analyzed by using X-ray photoelectron spectroscopy (XPS) and pyrolysis–gas chromatography with time-of-flight mass spectrometry (Py-GC/TOFMS). Removal rates of 20 mm2/min in area, 52 mm3/min in volume, and 7 μm/min in depth were achieved with an inter-electrode distance of 10.0 mm and an air flow rate of 20 standard liters per minute. A removal depth of 10 μm/min was achieved without air supply. The mechanism of stain removal by spark discharge was modeled by decomposing the original high-molecular-weight molecules in polyester-based urethane rubber into low-molecular-weight molecules, such as methylene diisocyanate (MDI) components. The results of this study may facilitate the development of a novel electric vacuum cleaner capable of removing floor stains.

Spectroscopic analysis of single and multiphase electrical discharge for clean energy conversion

Abstract In this study, we examined non-thermal atmospheric pressure plasma processes operating under varying conditions using different liquid and gaseous hydrocarbon materials. The light emission from the discharges were analyzed through optical emission spectroscopy to comprehend the products generated in different parameter space. The gaseous products from each of these analyses were also collected and analyzed through gas chromatography. Analysis of the optical emission from the discharge and concentration of the gaseous products show a linear trend between emission intensity ratio Hα/C2 and gas concentration ratio H2/C2Hx. Gas temperature and electronic excitation temperature of different experimental conditions were also compared and indicates that spark discharge relates to higher electronic excitation temperature compared to glow discharge of similar medium. Higher electronic excitation temperature leads to generation of different products from spark discharge compared to glow discharge. Glow discharge generates more of the intermediate products. Whereas spark discharge, because of its higher electronic excitation temperature, leads to higher rate of dissociation and therefore generates more of the dissociated products. Glow discharge, for example generates more of OH and H from the moisture present in the carrier gas as impurity, whereas spark discharge would generate more of Hα and O particles further breaking down the OH bonds. Finally, UV-Vis analysis was performed on the liquid products of the discharge and reveals that the photo-centers and the newly generated soot nano particles absorb the UV range lights and some of the visible range light emission mostly up to ~600nm.

Development of Functionalized Iron Oxide Nanoparticles Through Non-Thermal Atmospheric Pressure Plasma Assisted Polymerization for Reducing Cytotoxicity

Development of Functionalized Iron Oxide Nanoparticles Through Non-Thermal Atmospheric Pressure Plasma Assisted Polymerization for Reducing Cytotoxicity

Non-thermal atmospheric pressure plasma induces selective cancer cell apoptosis by modulating redox homeostasis

BackgroundAnticancer treatments aim to selectively target cancer cells without harming normal cells. While non-thermal atmospheric pressure plasma (NTAPP) has shown anticancer potential across various studies, the mechanisms behind its selective action on cancer cells remain inadequately understood. This study explores the mechanism of NTAPP-induced selective cell death and assesses its application in cancer therapy.MethodsWe treated HT1080 fibrosarcoma cells with NTAPP and assessed the intracellular levels of mitochondria-derived reactive oxygen species (ROS), mitochondrial function, and cell death mechanisms. We employed N-acetylcysteine to investigate ROS’s role in NTAPP-induced cell death. Additionally, single-cell RNA sequencing was used to compare gene expression in NTAPP-treated HT1080 cells and human normal fibroblasts (NF). Western blotting and immunofluorescence staining examined the expression and nuclear translocation of nuclear factor erythroid 2-related factor 2 (NRF2), a key antioxidant gene transcription factor. We also evaluated autophagy activity through fluorescence staining and transmission electron microscopy.ResultsNTAPP treatment increased ROS levels and induced mitochondrial dysfunction, leading to apoptosis in HT1080 cells. The involvement of ROS in selective cancer cell death was confirmed by N-acetylcysteine treatment. Distinct gene expression patterns were observed between NTAPP-treated NF and HT1080 cells, with NF showing upregulated antioxidant gene expression. Notably, NRF2 expression and nuclear translocation increased in NF but not in HT1080 cells. Furthermore, autophagy activity was significantly higher in normal cells compared to cancer cells.ConclusionsOur study demonstrates that NTAPP induces selective cell death in fibrosarcoma cells through the downregulation of the NRF2-induced ROS scavenger system and inhibition of autophagy. These findings suggest NTAPP’s potential as a cancer therapy that minimizes damage to normal cells while effectively targeting cancer cells.

A comparative study of gas temperature determination in non-thermal atmospheric pressure plasma jet by spectral analysis and scattering technique for plasma-catalyst measurements

Comparison and validation of different methods for the measurements of plasma gas temperature were studied. The investigations depend on optical emission spectroscopy OES, laser scattering technique, and line-broadening mechanisms. The rotational temperature of the second positive system SPS (C3 ∏+ u - B3 ∏+ g) around 380 nm, second positive system SPS at 337.1 nm of nitrogen molecule (C3 ∏+ u - B3 ∏+ g), and first negative system FNS at 391.4 nm of nitrogen ion (B2Σu +→X2Σg +) were investigated. Moreover, Raman scattering spectra at 532 nm were used to measure the gas temperature in the plasma jet. Gas temperature from the emission line broadening method was also calculated. The role of non-thermal plasma in assisting NOx reduction over an Ag/Al2O3 catalyst at low temperatures using simulated diesel fuels (toluene) was confirmed. Importantly, a significant activity of both NOx and hydrocarbons oxidation was observed and obtained at low gas temperatures. It was found that there is a clear correlation between the gas temperature and the conversion efficiency of the catalyst under different operating conditions of the plasma reactor. The main objective of this investigation was to confirm the important role of the non-thermal plasma in catalyst activation at low gas temperatures compared to traditional thermal activation.

Advances in Electrostatic Plasma Methods for Purification of Airborne Pathogenic Microbial Aerosols: Mechanism, Modeling and Application.

The transmission of pathogenic airborne microorganisms significantly impacts public health and societal functioning. Ensuring healthy indoor air quality in public spaces is critical. Among various air purification technologies, electrostatic precipitation and atmospheric pressure nonthermal plasma are notable for their broad-spectrum effectiveness, high efficiency, cost-effectiveness, and safety. This review investigates the primary mechanisms by which these electrostatic methods collect and disinfect pathogenic aerosols. It also delves into recent advancements in enhancing their physical and chemical mechanisms for improve efficiency. Simultaneously, a thorough summary of mathematical models related to the migration and deactivation of pathogenic aerosols in electrostatic purifiers is provided. It will help us to understand the behavior of aerosols in purification systems. Additionally, the review discusses the current research on creating a comprehensive health protection system and addresses the challenges of balancing byproduct control with efficiency. The aim is to establish a foundation for future research and development in electrostatic aerosol purification and develop integrated air purification technologies that are both efficient and safe.

Influence of pre-treatment with non-thermal atmospheric pressure plasma on bond strength of TP340 titanium-PEEK direct bonding

Direct bonding of a TP340 titanium to PEEK by hot pressing via pre-treatment of non-thermal atmospheric pressure plasma jet has been demonstrated. The plasma irradiation effect on the bonding surface on the bond strength after hot pressing was investigated. The tensile shear strength of TP340-PEEK joined by hot pressing after plasma pre-treatment was measured by comparing specimens bonded using conventional hot pressing and those bonded using adhesives. The plasma treatment to the TP340 side resulted in the formation of TiO2, which is chemically fed to oxide formation due to the irradiation of oxygen radicals generated by the plasma, resulting in a bond strength of less than 1 MPa, similar to the bond strength of the untreated specimens. The plasma irradiation effect on the PEEK side on the bond strength of TP340-PEEK bonded samples was also investigated. The bonding strength was increased by plasma irradiation to PEEK. As the plasma irradiation time was increased, the bonding strength gradually increased to 9.2 MPa, which is about 19 times higher than the bonding strength without plasma irradiation. These results suggest that oxygen radicals in the atmospheric pressure RF plasma jet produced oxygen-containing surface functional groups on the PEEK surface, which increased the strength of the TP340-PEEK direct joining.

Non-thermal atmospheric-pressure plasma exposure as a practical method for improvement of Brassica juncea seed germination

Here we report that non-thermal atmospheric-pressure plasma exposure can improve Brassica juncea (leaf mustard) seed germination rate from 50 % to 98 %. The commercially relevant germination rate was achieved by plasma exposure for only 10 minutes and the effect sustains at least for one month under an appropriate storage condition. Improved germination by plasma exposure was also observed for Brassica rapa subsp. pekinensis (Chinese cabbage) seeds. The plasma device used is simple. No pure gas flow system is necessary and it is easy to handle. A large number of seeds can be treated by simply scaling up the device. Plasma exposure can be a practical method for improving seed germination of crop plants important for agriculture.

Non-Linear Phenomena in Voltage and Frequency Converters Supplying Non-Thermal Plasma Reactors

Atmospheric pressure cold plasmas have recently been the subject of intense research and applications for solving problems in the fields of energy, environmental engineering, and biomedicine. Non-thermal atmospheric pressure plasma sources, with dielectric barrier discharges, plasma jets, and arc discharges, are non-linear power loads. They require special power systems, which are usually designed separately for each type of plasma reactor, depending on the requirements of the plasma-chemical process, the power of the receiver, the type of process gas, the current, voltage and frequency requirements, and the efficiency of the power source. This paper presents non-linear phenomena accompanying plasma generation in the power supply plasma reactor system, such as harmonic generation, resonance, and ferroresonance of currents and voltages, and the switching of overvoltages and pulse generation. When properly applied, this can support the operation of the above-mentioned reactors by providing improved discharge ignition depending on the working gas, thus increasing the efficiency of the plasma process and improving the cooperation of the plasma-generation system with the power supply.

Effects of different plasma treatments on bonding properties of zirconia

This in vitro study was to evaluate the effect of different non-thermal atmospheric pressure plasma (NTP) on shear bond strength (SBS) between yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and self-adhesive resin cement. In this study, The Y-TZP specimens were divided into 4 groups according to the surface treatment methods as follows: Control (no surface treatment), Sb (Sandblasting), AP(argon NTP), and CP(20 % oxygen and 80 % argon combination NTP). Y-TZP specimens were randomly selected from each group to observe and test the following indexes: scanning electron microscope to observe the surface morphology; atomic force microscope to detect the surface roughness; contact angle detector to detect the surface contact angle; energy spectrometer to analyze the surface elements. Then, resin cement (Rely X–U200) was bonded to human isolated teeth with Y-TZP specimens to measure SBS. The results showed that for the SE test, the NTP group was significantly higher than the control group (p < 0.05). The results of the SBS test showed that the SBS values of the NTP group were significantly higher than those of the other groups, regardless of the plasma treatment (p < 0.05). However, there was no significant difference between groups AP and CP in a test of SBS (p > 0.05). This study shows that non-thermal atmospheric pressure plasma can improve the shear bond strength of Y-TZP by increasing the surface energy. The addition of oxygen ratio to argon is more favorable to increase the shear bond strength and is worth further investigation.

Fracture healing on non-union fracture model promoted by non-thermal atmospheric-pressure plasma.

Non-thermal atmospheric-pressure plasma (NTAPP) is attracting widespread interest for use in medical applications. The tissue repair capacity of NTAPP has been reported in various fields; however, little is known about its effect on fracture healing. Non-union or delayed union after a fracture is a clinical challenge. In this study, we aimed to investigate how NTAPP irradiation promotes fracture healing in a non-union fracture model and its underlying mechanism, in vitro and in vivo. For the in vivo study, we created normal and non-union fracture models in LEW/SsNSlc rats to investigate the effects of NTAPP. To create a fracture, a transverse osteotomy was performed in the middle of the femoral shaft. To induce the non-union fracture model, the periosteum surrounding the fracture site was cauterized after a normal fracture model was created. The normal fracture model showed no significant difference in bone healing between the control and NTAPP-treated groups. The non-union fracture model demonstrated that the NTAPP-treated group showed consistent improvement in fracture healing. Histological and biomechanical assessments confirmed the fracture healing. The in vitro study using pre-osteoblastic MC3T3-E1 cells demonstrated that NTAPP irradiation under specific conditions did not reduce cell proliferation but did enhance osteoblastic differentiation. Overall, these results suggest that NTAPP is a novel approach to the treatment of bone fractures.

Inhibition of glutamine metabolism increases sensitivity to plasma-activated medium-induced cytotoxicity

Non-thermal atmospheric pressure plasma (NTP), an ionized gas containing electrons, ions, radicals, and photons, has various biological effects, including wound healing and anticancer effects. Plasma-activated medium (PAM), which is prepared by irradiating medium with NTP, preferentially kills cancer cells. Large amounts of reactive oxygen species (ROS) and reactive nitrogen species (RNS) included in PAM are closely related to its anticancer effects. The precise mechanism of PAM-induced cytotoxicity is not fully understood; however, PAM exposure has been reported to reduce cellular energy metabolism. Glutamine (Gln) is an important amino acid as an energy source in cancer cells. Gln is converted to glutamate by glutaminase (GLS), and is utilized to synthesize ATP and glutathione (GSH). Expression levels of GLS have been shown to be higher in certain types of cancers. In this study, we examined the effects of GLS inhibition on PAM cytotoxicity using breast cancer MDA-MB-231 cells. Pretreatment with BPTES, a glutaminase 1 (GLS1) inhibitor, dose-dependently enhanced PAM-induced cell death. PAM-induced ROS production and γ-H2AX formation, a DNA damage marker, were increased in cells pretreated with BPTES compared with PAM alone. BPTES pretreatment enhanced a PAM-induced decrease in intracellular GSH, indicating the possibility that BPTES reduces the antioxidant capacity of MDA-MB-231 cells. In addition, BPTES pretreatment enhanced PAM-induced loss of the mitochondrial membrane potential and reduction of ATP production. Moreover, GLS1 knockdown promoted PAM-induced cell death. Taken together, the combination of GLS1 inhibitors such as BPTES is considered to be useful for enhancing the cytotoxic effects of PAM against cancer cells.

Unlocking melanoma Suppression: Insights from Plasma-Induced potent miRNAs through PI3K-AKT-ZEB1 axis

IntroductionMelanoma is a rare but highly malignant form of skin cancer. Although recent targeted and immune-based therapies have improved survival rates by 10–15%, effective melanoma treatment remains challenging. Therefore, novel, combinatorial therapy options such as non-thermal atmospheric pressure plasma (NTP) are being investigated to inhibit and prevent chemoresistance. Although several studies have reported the apoptotic and inhibitory effects of reactive oxygen species produced by NTP in the context of melanoma, the intricate molecular network that determines the role of microRNAs (miRNAs) in regulating NTP-mediated cell death remains unexplored. ObjectivesThis study aimed to explore the molecular mechanisms and miRNA networks regulated by NTP-induced oxidative stress in melanoma cells. MethodsMelanoma cells were exposed to NTP and then subjected to high-throughput miRNA sequencing to identify NTP-regulated miRNAs. Various biological processes and underlying molecular mechanisms were assessed using Alamar Blue, propidium iodide (PI) uptake, cell migration, and clonogenic assays followed by qRT-PCR and flow cytometry. ResultsNTP exposure for 3 min was sufficient to modulate the expression of several miRNAs, inhibiting cell growth. Persistent NTP exposure for 5 min increased differential miRNA regulation, PI uptake, and the expression of genes involved in cell cycle arrest and death. qPCR confirmed that miR-200b-3p and miR-215-5p upregulation contributed to decreased cell viability and migration. Mechanistically, inhibiting miR-200b-3p and miR-215-5p in SK-2 cells enhancedZEB1, PI3K, and AKT expression, increasing cell proliferation and viability. ConclusionThis study demonstrated that NTP exposure for 5 min results in the differential regulation of miRNAs related to the PI3K-AKT-ZEB1 axis and cell cycle dysregulation to facilitate melanoma suppression.

Comparison of Electron Densities and Temperatures in Helium and Argon Nonthermal Atmospheric-Pressure Plasmas by Continuum Spectral Analysis

Comparison of Electron Densities and Temperatures in Helium and Argon Nonthermal Atmospheric-Pressure Plasmas by Continuum Spectral Analysis

Activation of the hair follicle stem cells by low temperature pulsed plasma jet

The issue of hair loss has become an increasing concern due to growing societal pressures. Currently available hair loss treatments often produce unsatisfactory results, cause significant physical damage, and are costly. Non-thermal atmospheric pressure plasma has been widely used in various biomedical fields, including sterilization, coagulation promotion, and cancer treatment. This paper pioneered the use of a kind of portable pulsed plasma jet power supply in the resting period of mouse hair follicle, and found that plasma jet can effectively shorten the resting period of mouse hair follicle, so that they re-enter the regeneration period and grow hair. Plasma jet provides a new treatment method for hair loss that is cheap, simple, highly effective, has no side effects and has broad application prospects.

In vivo study on the repair of rat Achilles tendon injury treated with non-thermal atmospheric-pressure helium microplasma jet.

Non-thermal atmospheric-pressure plasma (NTAPP) has been widely studied for clinical applications, e.g., disinfection, wound healing, cancer therapy, hemostasis, and bone regeneration. It is being revealed that the physical and chemical actions of plasma have enabled these clinical applications. Based on our previous report regarding plasma-stimulated bone regeneration, this study focused on Achilles tendon repair by NTAPP. This is the first study to reveal that exposure to NTAPP can accelerate Achilles tendon repair using a well-established Achilles tendon injury rat model. Histological evaluation using the Stoll's and histological scores showed a significant improvement at 2 and 4 weeks, with type I collagen content being substantial at the early time point of 2 weeks post-surgery. Notably, the replacement of type III collagen with type I collagen occurred more frequently in the plasma-treated groups at the early stage of repair. Tensile strength test results showed that the maximum breaking strength in the plasma-treated group at two weeks was significantly higher than that in the untreated group. Overall, our results indicate that a single event of NTAPP treatment during the surgery can contribute to an early recovery of an injured tendon.

Study of dual Z-scheme photocatalytic response of TiO2/Ag/ZnO coating on plasma-modified cotton fabric for self-cleaning application

An innovative approach was adopted to improve the photocatalytic response of nanoparticle-coated cotton fabric for self-cleaning application. Fabrics with layers of TiO2, Ag, and ZnO nanoparticles were assessed for photodegradation of Rhodamine B, methyl orange, and methyl red. A dual-scheme charge transfer method was designed for the photocatalytic activity of TiO2/Ag/ZnO nanoparticles on cotton fabric. To produce the multilayer structure of nanoparticles, the fabric was first functionalized with atmospheric pressure nonthermal plasma and then sonochemically coated with TiO2/Ag/ZnO in a layered form. The plasma functionalization enhanced the stability of TiO2/Ag/ZnO nanoparticles on the fabric. It was revealed that a combination of Ag, TiO2, and ZnO nanoparticles produced a Schottky barrier among the silver metal and metal oxides (TiO2 and ZnO), resulting in enhanced photocatalytic properties. Methyl red underwent the highest photocatalytic degradation of 93% over the designed photocatalyst-coated fabric after 120 min of light exposure. This study provides a promising strategy for improving the photocatalytic self-cleaning efficacy of nanocoated fabrics.

Nanoscale visualization of the anti-tumor effect of a plasma-activated Ringer's lactate solution.

Plasma-activated Ringer's lactate solutions (PALs), which are Ringer's lactate solutions treated with non-thermal atmospheric-pressure plasma, have an anti-tumor effect and can be used for chemotherapy. As the anti-tumor effect of the PAL is influenced by the cell-treatment time, it is necessary to monitor the structural changes of the cell surface with non-invasive, nanoscale, and time-lapse imaging to understand the anti-tumor effect. In this study, to characterize the anti-tumor effect of the PAL, we used scanning ion conductance microscopy (SICM), using glass nanopipettes as probes, to visualize the structural changes of the cell surface. SICM time-lapse topographic imaging visualized a decrease in the movement of lamellipodia in normal cells and cancer cells after the PAL treatment. Furthermore, in normal cells, protrusive structures were observed on the cell surface. Time-lapse imaging using SICM allowed us to characterize the differences in the morphological changes between the normal and cancer cells upon exposure to the PAL.