Non-thermal Atmospheric Pressure Plasma Research Articles

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.

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.

Characterization of Plasma Activated Water Generated from Gliding Arc Discharge and Its Application on Enhancement of Seed Germination of Radish (Raphanus sativus var. longipinnatus)

In recent decades, generation of plasma activated water (PAW) from non-thermal atmospheric pressure plasma sources has received enormous attention due to their diverse applications. The research described in this paper is mainly focused on the preparation and characterisations of PAW produced from gliding arc discharge (GAD) operated with high voltages (9.7 kV, 50 Hz) power supply system and its use in the enhancement of seed germination of radish. The physical and chemical parameters of the PAW are investigated using a multi-parameter probe and UV-visible spectrometer. There are significant differences in physical parameters like pH and conductivity, and chemical parameters like concentration of nitrates, nitrites, ammonia in untreated and PAW.  But no significant differences in temperature and total dissolved oxygen (TDO) are found. In order to determine the effects of PAW on seed germination, different germination parameters are calculated on radish (Raphanus sativus) which indicates that PAW can enhance the seed germination of radish.

Growth Stimulation of Durum Wheat and Common Buckwheat by Non-Thermal Atmospheric Pressure Plasma.

The grains of durum wheat (Triticum durum Desf.) and achenes of common buckwheat (Fagopyrum esculentum Moench) were tested after treatment with two sources of non-thermal atmospheric pressure plasma (DCSBD, MSDBD) with different treatment times (0, 3, 5, 10, 20, 30, and 40 s). The effect of these treatments was monitored with regard to the seed surface diagnostics (water contact angle-WCA, chemical changes by Fourier transform infrared spectroscopy-FTIR); twenty parameters associated with germination and initial seed growth were monitored. A study of the wettability confirmed a decrease in WCA values indicating an increase in surface energy and hydrophilicity depending on the type of seed, plasma source, and treatment time. Surface analysis by attenuated total reflectance FTIR (ATR-FTIR) showed no obvious changes in the chemical bonds on the surface of the plasma-treated seeds, which confirms the non-destructive effect of the plasma on the chemical composition of the seed shell. A multivariate analysis of the data showed many positive trends (not statistically significant) in germination and initial growth parameters. The repeated results for germination rate and root/shoot dry matter ratio indicate the tendency of plants to invest in underground organs. Durum wheat required longer treatment times with non-thermal plasma (10 s, 20 s) for germination and early growth, whereas buckwheat required shorter times (5 s, 10 s). The responses of durum wheat grains to the two non-thermal plasma sources used were equal. In contrast, the responses of buckwheat achenes were more favorable to MSDBD treatment than to DCSBD.

Influence of pre-treatment using non-thermal atmospheric pressure plasma jet on aluminum alloy A1050 to PEEK direct joining with hot-pressing process

Abstract  Aluminum alloy A1050 to polyetheretherketone (PEEK) direct joining with hot-pressing process via pre-treatment using non-thermal atmospheric pressure plasma jet has been performed. The effect of plasma irradiation on the tensile shear strength of A1050-PEEK direct bonded specimens joined by a combination of hot-pressing process and pre-plasma treatment using non-thermal atmospheric pressure plasma jet was investigated. A1050-PEEK bonded samples with plasma-treated PEEK only showed high tensile shear stress of 13.4 MPa. This increase in tensile shear strength is attributed to the addition of oxygen functional groups on the surface of the PEEK by reactive oxygen species produced by the plasma jet.

Availability and reactivity of N2(v) for NH3 synthesis by plasma catalysis

Production of vibrationally excited N2 (N2(v)) in atmospheric pressure nonthermal plasma and loss of N2(v) by gas-phase reactions and reactions on catalytic surfaces are analyzed to examine the role of N2(v) in NH3 formation by plasma catalysis. Vibrational state-to-state kinetic models complemented with molecular beam mass spectrometry (MBMS) measurements demonstrate that N2(v> 0) is produced with densities 100× greater than the density of N radicals by a radiofrequency atmospheric pressure plasma jet. The experimentally measured loss of N2(v) corresponds with a state-to-state kinetic model that describes loss of N2(v) by surface-mediated vibrational relaxation without consideration of reactions that convert N2(v) to NH3 over the catalyst surface. Rate constants for vibrational relaxation of N2(v) on catalyst surfaces exceed upper bounds on proposed rate constants for NH3 formation reactions from N2(v) over Fe when v < 9, Ni when v < 18, and Ag when v < 39, which indicates that only higher vibrational levels can possibly contribute to catalytic NH3 formation faster than they undergo vibrational relaxation on the surface. Densities of N2(v> 8), vibrational levels that can possibly react over Fe to form NH3 faster than they undergo vibrational relaxation, are less than or similar to N densities at the inlet of the catalyst bed and measured NH3 formation for the investigated conditions in this work, while densities of N2(v> 17) and N2(v> 38) are orders of magnitude below the N density at the inlet of the catalyst bed and the measured NH3 formation. The loss of N2(v) by vibrational relaxation on the surface limits the ability of N2(v) to contribute to catalytic NH3 formation and explains why N2(v) does not produce NH3 in quantities that are comparable to NH3 formation from N even though N2(v > 0) is more abundantly produced by the plasma.

Cellular responses to compound stress induced by atmospheric-pressure plasma in fission yeast.

The stress response is one of the most fundamental cellular processes. Although the molecular mechanisms underlying responses to a single stressor have been extensively studied, cellular responses to multiple stresses remain largely unknown. Here, we characterized fission yeast cellular responses to a novel stress inducer, non-thermal atmospheric-pressure plasma. Plasma irradiation generates ultraviolet radiation, electromagnetic fields and a variety of chemically reactive species simultaneously, and thus can impose multiple stresses on cells. We applied direct plasma irradiation to fission yeast and showed that strong plasma irradiation inhibited fission yeast growth. We demonstrated that mutants lacking sep1 and ace2, both of which encode transcription factors required for proper cell separation, were resistant to plasma irradiation. Sep1-target transcripts were downregulated by mild plasma irradiation. We also demonstrated that plasma irradiation inhibited the target of rapamycin kinase complex 1 (TORC1). These observations indicate that two pathways, namely the Sep1-Ace2 cell separation pathway and TORC1 pathway, operate when fission yeast cope with multiple stresses induced by plasma irradiation.

Generation of Plasma-Activated Fluids for Successful Disinfection of Pseudomonas aeruginosa in Liquid Environments and Determination of Microbial Damage

The application of the non-thermal atmospheric pressure plasma technology is a promising tool for microbial inactivation. During the activation process, many reactive substances and radicals arise associated with physicochemical changes in the fluid and massive pH drop. In this study, we analyzed and optimized plasma activation settings and conditions of water and liquids to obtain inactivation of the waterborne microorganism Pseudomonas aeruginosa in a liquid environment. The minimal electrical output was 60 Watt with 20 min activation time followed by 30 min contact time with 108 cells/mL. Using higher electrical power (&gt;90 W) with a Lab Unit generating plasma-activated water, a shorter activation time (&lt;10 min) was sufficient for bacterial inactivation. The organic and inorganic composition of the activated liquid with different mineral salt concentrations is of utmost importance for the yield of reactive species during the plasma activation process and consequently for the antimicrobial effect. Plasma-activated fluids with high organic and inorganic contents demonstrated lower inactivation efficiencies than low loaded fluids; yet antimicrobial efficacy could be achieved by increasing the electrical power and activation time. For sufficient inactivation of bacterial suspensions, at least half a volume unit of plasma-activated water had to be added after appropriately optimized activation. Further dilutions reduced the antimicrobial effect. PAW lost activity after being left standing for a prolonged time after activation, so for maximizing the antimicrobial effect a direct use after activation is recommendable. Bacterial inactivation was shown by the absence of colony forming units on culture media and, at the molecular level, damage to the membrane and inactivation of enzymes were observed. Plasma-activated fluids demonstrated a high potential in applications as microbiological disinfectant in liquids.

Nem termikus atmoszférikus plazma használata a bőr in situ laphámsejtes karcinómájának kezelésére: esetismertetés

Despite its high incidence, cutaneous squamous cell carcinoma (SCC) remains a treatment challenge. Non-thermal, atmospheric pressure plasma (NTAP) is an emerging modality with a broad range of potential applications in dermatology, including the treatment of actinic keratosis. Given the close relationship between actinic keratosis and SCC, we treated three patients with biopsy-proven in-situ SCC, using NTAP. All three patients have tolerated the treatment very well, and they all reached full clinical resolution of their lesion after 2-5 treatment sessions. This case series highlights the potential role of NTAP in the treatment of SCC.

Cold atmospheric pressure air plasma jet disinfection of table eggs: Inactivation of Salmonella enterica, cuticle integrity and egg quality

Eggshell cuticles are first lines of defense against egg-associated pathogens, such as Salmonella enterica serovar Enteritidis (SE). Infections from eggs contaminated with this strain remain a significant risk. In addition, changes in the cuticle are closely related to changes in egg safety. The emerging non-thermal atmospheric pressure plasma technology enables a high rate of microbial inactivation at near-ambient temperatures, making it ideal for food safety applications. This study examines the effects of a cold atmospheric pressure air plasma jet (CAAP-J) on eggshell cuticle and egg quality whilst inactivating SE. Shell eggs inoculated with SE (7 log10 cfu/egg) were used as the samples to test the decontamination performance of the device. The tests were conducted using an industrial CAAP-J with different power levels (600–800 W), exposure times (60–120 s), at a fixeddistance of 20 mm from the plasma jet and an air flow rate of 3600 L/h. It was found that the best results were obtained after 120 s at maximum plasma power (800 W). Subsequent to the implementation of this plasma procedure, it was determined that no viable cells could be detected. After CAAP-J treatment, the temperature remains below 50.5 °C, thereby minimizing the risk of altering egg quality. All specific measurements (egg white pH, yolk pH, yolk color, HU, and eggshell breaking strength) have shown that CAAP-J treatment has no negative effect on egg quality. No changes in eggshell cuticle quality after CAAP-J treatment was confirmed through scanning electron microscope (SEM).

Improvement of transdermal absorption rate by nonthermal biocompatible atmospheric pressure plasma

Nonthermal biocompatible plasma (NBP) is a promising option for improving medication absorption into the human skin. Currently, most plasma devices for cosmetics employ a floating-electrode plasma source for treating the skin. Human skin serves as the ground electrode in the floating-electrode plasma discharge, and discharge occurs between the skin and electrodes of the device. In this in vitro study, we aimed to evaluate the effect of NBP on the skin permeation of niacinamide. We have quantified the transdermal absorption rates of niacinamide in both untreated skin and skin treated with NBP for a duration of 10 s. The absorption of niacinamide for both without and with NBP treatment was observed until 12 h incubation time. Without plasma treatment, the human skin exhibited stable and low transdermal absorption of niacinamide up to 12 h. However, the NBP treatment significantly increased the transdermal absorption of niacinamide from 0.5 h to 6 h and continuously increased skin penetration over a duration of more than 12 h incubation period. The obtained results suggest that NBP-treated human skin showed a 60-fold higher penetration rate than non-treated skin. The increased penetration rate of niacinamide can be mainly attributed to plasmaporation subsequent to NBP treatment. The findings of this study demonstrate that NBP treatment results in remarkable skin permeability, making it a promising candidate for both cosmetic and pharmaceutical delivery applications.

On the Effect of Non-Thermal Atmospheric Pressure Plasma Treatment on the Properties of PET Film.

The aim of the work was to investigate the effect of non-thermal plasma treatment of an ultra-thin polyethylene terephthalate (PET) film on changes in its physicochemical properties and biodegradability. Plasma treatment using a dielectric barrier discharge plasma reactor was carried out in air at room temperature and atmospheric pressure twice for 5 and 15 min, respectively. It has been shown that pre-treatment of the PET surface with non-thermal atmospheric plasma leads to changes in the physicochemical properties of this polymer. After plasma modification, the films showed a more developed surface compared to the control samples, which may be related to the surface etching and oxidation processes. After a 5-min plasma exposure, PET films were characterized by the highest wettability, i.e., the contact angle decreased by more than twice compared to the untreated samples. The differential scanning calorimetry analysis revealed the influence of plasma pretreatment on crystallinity content and the melt crystallization behavior of PET after soil degradation. The main novelty of the work is the fact that the combined action of two factors (i.e., physical and biological) led to a reduction in the content of the crystalline phase in the tested polymeric material.

From seed to sprout: Unveiling the potential of non-thermal plasma for optimizing cucumber growth

Background and aimsNumerous strategies for enhancing seed germination and growth have been employed over the decades. Despite these advancements, there continues to be a demand for more effective techniques, driven by the growing global population. Recently, various forms of non-thermal atmospheric pressure plasma have garnered attention as environmentally friendly, safe, and cost-effective methods to enhance the agricultural and food sectors. This study explores the remarkable impact of non-thermal plasma (NTP) treatment on cucumber (Cucumis sativus L.) seed germination. MethodsA cost-effective, custom-designed power supply operating at line frequency was used for treating seeds, with exposure times ranging from 1 to 7 min. Various germination parameters, including water contact angle measurements, mass loss, water imbibition rate, and seedling length, were evaluated to assess the impact of plasma treatment on seed germination. ResultsCucumber seeds exposed to NTP treatment for 3 min and 5 min durations showed significant germination improvements, notably a 57.9 ± 4.25 % higher final germination percentage, 14.5 ± 3.75 % reduced mean germination time, and a remarkable 90.6 ± 4.64 % increase in germination index compared to the control. These results suggest that NTP treatment enhanced seed coat permeability, triggered essential biochemical processes, and expedited water absorption and nutrient assimilation, ultimately fostering faster and more synchronized germination. ConclusionsOur findings underscore the potential of NTP as an innovative approach to improving seed germination in agricultural practices.

Non-thermal atmospheric pressure plasma treatment increases hydrophilicity and promotes cell growth on titanium alloys in vitro

Most medical implants are made of titanium. When titanium is exposed to air for a long time, hydrocarbons are deposited and the surface becomes hydrophobic. Cell attachment is important for bone ingrowth to occur on the implant surface, and hydrophilicity can enhance this. We examined whether non-thermal atmospheric pressure plasma treatment could increase the hydrophilicity of the titanium surface. Samples coated with four widely used coating types [grit blasting, micro arc oxidation (MAO), titanium plasma spray (TPS), and direct metal fabrication (DMF)] were treated with plasma. Each of the four surface-treated samples was divided into groups with and without plasma treatment. We analysed wettability by surface analysis and evaluation of contact angles, cell proliferation, and adhesion using scanning electron microscopy (SEM), confocal laser scanning microscopy, absorbance tests, and alkaline phosphatase (ALP) activity assay; four different Ti6Al4V surface types were compared. After plasma treatment, the contact angle was reduced on all surfaces, and the carbon content was reduced on all surfaces based on X-ray photoelectron spectroscopy (XPS) surface analysis. Under confocal laser scanning, the cell layer was thicker on the plasma-treated samples, especially in groups TPS and DMF. Cell proliferation was 41.8%, 17.7%, 54.9%, and 83.8% greater for the plasma- than non-plasma-treated grit blasting, MAO, TPS, and DMF samples, respectively. Hydrophilicity increased significantly under plasma treatment, and biological responsivity was also improved.

Hydrogen from cellulose and low-density polyethylene via atmospheric pressure nonthermal plasma

The valorization of waste, by creating economic value while limiting environmental impact, can have an essential role in sustainable development. Particularly, polymeric waste such as biomass and plastics can be used for the production of green hydrogen as a carbon-free energy carrier through the use of nonthermal plasma powered by renewable, potentially surplus, electricity. In this study, a Streamer Dielectric-Barrier Discharge (SDBD) reactor is designed and built to extract hydrogen and carbon co-products from cellulose and low-density polyethylene (LDPE) as model feedstocks for biomass and plastic waste, respectively. Spectroscopic and electrical diagnostics, together with modeling, are used to estimate representative plasma properties, namely electron and excitation temperatures, number density, and power consumption. Cellulose and LDPE are plasma-treated for different treatment times to characterize the evolution of the hydrogen production process. Gas products are analyzed using gas chromatography to determine the mean hydrogen production rate, production efficiency, hydrogen yield, selectivity, and energy cost. The results show that the maximum hydrogen production efficiency for cellulose is 0.8 mol/kWh, which is approximately double that for LDPE. Furthermore, the energy cost of hydrogen production from cellulose is 600 kWh/kg of H2, half that of LDPE. Solid products are examined via scanning electron microscopy, revealing the distinct morphological structure of the two feedstocks treated, as well as by elemental composition analysis. The results demonstrate that SDBD plasma is effective at producing hydrogen from cellulose and LDPE at near atmospheric pressure and relatively low-temperature conditions in rapid-response and compact processes.

A novel approach to expedite wound healing with plasma brush of cold flame

Excessive or persistent infection is a major contributing factor in impeding chronic wound healing. Wound bed preparations using antiseptics do not necessarily target the entire bacterial spectrum, and the highly proliferating granulation tissue may be sensitive to the cytotoxic effects, impairing tissue repair. Non-thermal gas atmospheric pressure plasmas are partially ionized gases that contain highly reactive particles while the gas phase remains near room temperature, thus having the capability of accessing small irregular cavities and fissures and killing bacteria because of the diffusive nature of gas phase plasma species that are chemically reactive, providing an ideal approach to topical wound disinfection. A non-thermal plasma brush device of novel design has been developed that is suitable for clinical application in the disinfection of oral and wound bacteria. In vivo studies have indicated that the plasma brush treatment rendered no harmful effect on healthy skin or tissues, while it could improve wound healing in Pseudomonas aeruginosa biofilm infected wounds exposed to an optimized treatment with argon plus 1% nitrogen (Ar + N2) plasma.