Human coronavirus 229E inactivation on porous and nonporous materials using dielectric barrier discharge (DBD) plasma.

Viruses can spread through contaminated aerosols and contaminated surface materials, and effective disinfection techniques are essential for virus inactivation. Nonthermal plasma-generated reactive oxygen and nitrogen species can effectively inactivate the coronavirus. We aim to interpret the coronavirus inactivation level and mechanism of surface interaction with materials with and without dielectric barrier discharge (DBD) plasma treatment. Nonthermal plasma, particularly surface-type DBD plasma, can inactivate human coronavirus 229E (HCoV-229E) on porous (paper, wood, mask) and nonporous (plastic, stainless steel, glass, Cu) materials. Virus inactivation was analyzed using a 50% tissue culture infectivity dose (TCID50) using cell line, flow cytometry, and immunofluorescence. Surfaces contaminated with HCoV-229E were treated at different time intervals (0-5 h) with and without plasma exposure (natural decay in ambient air conditions). HCoV-229E persistence conformed to the following order: plastic > cover glass > stainless steel > mask > wood > paper > Cu with and without plasma exposure. HCoV-229E was more stable in plastic, cover glass, and stainless steel in 5 h, and the viable virus titer gradually decreased from its initial log10 order of 6.892 to 1.72, 1.53, and 1.32 TCID50/mL, respectively, under plasma exposure. No virus was observed in Cu after treatment for 5 h. The use of airflow, ambient nitrogen, and argon did not promote virus inactivation. Flow cytometry and immunofluorescence analysis demonstrated a low expression level of spike protein (fluorescence intensity) during plasma treatment and in E and M genes expression compared with the virus control.

Persistence of Coronavirus on Surface Materials and Its Control Measures Using Nonthermal Plasma and Other Agents.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been responsible for the initiation of the global pandemic since 2020. The virus spreads through contaminated air particles, fomite, and surface-contaminated porous (i.e., paper, wood, and masks) and non-porous (i.e., plastic, stainless steel, and glass) materials. The persistence of viruses on materials depends on porosity, adsorption, evaporation, isoelectric point, and environmental conditions, such as temperature, pH, and relative humidity. Disinfection techniques are crucial for preventing viral contamination on animated and inanimate surfaces. Currently, there are few effective methodologies for preventing SARS-CoV-2 and other coronaviruses without any side effects. Before infection can occur, measures must be taken to prevent the persistence of the coronavirus on the surfaces of both porous and non-porous inanimate materials. This review focuses on coronavirus persistence in surface materials (inanimate) and control measures. Viruses are inactivated through chemical and physical methods; the chemical methods particularly include alcohol, chlorine, and peroxide, whereas temperature, pH, humidity, ultraviolet irradiation (UV), gamma radiation, X-rays, ozone, and non-thermal, plasma-generated reactive oxygen and nitrogen species (RONS) are physical methods.

Anticancer Activity of Liquid Treated with Microwave Plasma-Generated Gas through Macrophage Activation.

Reactive nitrogen species (RNS), including nitric oxide (NO·) has been known as one of the key regulatory molecules in the immune system. In this study, we generated RNS-containing water treated with microwave plasma-generated gas in which the major component was nitric oxide (PGNO), and the effect on the macrophage polarization was investigated. The RNS-containing water was diluted in complete cell culture media (PGNO-solution) into the concentration that did not induce cell death in RAW 264.7 murine macrophages. PGNO-solution upregulates M1-type macrophage activation and downregulates the characteristics of M2-type macrophage at the transcriptional level. In addition, the PGNO-solution-treated M2-like macrophages had higher potential in killing melanoma cells. The anticancer potential was also investigated in a syngeneic mouse model. Our results show that PGNO-solution has the potential to convert the fate of macrophages, suggesting PGNO-solution treatment as a supportive method for controlling the function of macrophages under the tumor microenvironment.

Dynamics of nitric oxide level in liquids treated with microwave plasma-generated gas and their effects on spinach development.

In this study, we generated water and phosphate buffer treated with microwave plasma-generated gas in which the major component was nitric oxide (PGNO), and investigated the efficiency of the treated water and buffer in fertilization and sanitation. Real time NO level monitored by an electrode sensor was linearly increased over PGNO injection time, and removal of O2 from liquid before PGNO injection accelerated NO assimilation into liquids. Residual NO was still present 16 h after PGNO injection was stopped. H2O2, NO2-, and NO3- were also detected in PGNO-treated liquids. Spinach plants applied with 10 and 30 times diluted PGNO-treated water and 0.5 mM phosphate buffer showed slightly higher height and dry weight than control after 5 weeks. Plants grown with 10 and 30 times diluted PGNO-treated water exhibited the increased tolerance to water deficiency. Significant anti-microbial activity within 1 h was observed in un-diluted and in half-diluted PGNO-treated water and 0.5 mM phosphate buffer. Our results suggest that water or phosphate buffer containing NO, H2O2, NO2-, and NO3- can be produced by PGNO treatment, and that PGNO-treated water or buffer can be used as a potential fertilizer enhancing plant vitality with sanitation effect.

Bacterial inactivation by plasma treated water enhanced by reactive nitrogen species.

There is a growing body of literature that recognizes the importance of plasma treated water (PTW) for inactivation of microorganism. However, very little attention has been paid to the role of reactive nitrogen species (RNS) in deactivation of bacteria. The aim of this study is to explore the role of RNS in bacterial killing, and to develop a plasma system with increased sterilization efficiency. To increase the concentration of reactive oxygen and nitrogen species (RONS) in solution, we have used vapor systems (DI water/HNO3 at different wt%) combined with plasma using N2 as working gas. The results show that the addition of the vapor system yields higher RONS contents. Furthermore, PTW produced by N2 + 0.5 wt% HNO3 vapor comprises a large amount of both RNS and ROS, while PTW created by N2 + H2O vapor consists of a large amount of ROS, but much less RNS. Interestingly, we observed more deactivation of E. Coli with PTW created by N2 + 0.5 wt% HNO3 vapor plasma as compared to PTW generated by the other plasma systems. This work provides new insight into the role of RNS along with ROS for deactivation of bacteria.

Influence of oxygen on generation of reactive chemicals from nitrogen plasma jet.

A nonthermal plasma jet is operated at atmospheric pressure inside a vacuum chamber filled with nitrogen gas. Various chemical compounds are fabricated from nitrogen and water molecules in plasma jet with varying oxygen content. Detailed theoretical investigation of these chemical compounds is carried out in terms of different oxygen ratio ξ. Experimental measurements are also carried out for comparison with theoretical results. Hydroxyl molecules are mostly generated at surface of water, and some of them can penetrate into water. The density of hydroxyl molecules has its maximum without oxygen, and decreases to zero as ξ increases to 0.25. The density of the ammonia of NH3 also deceases as ξ increases to 0.25. On the other hand, theory and experiment show that the density of the NO3 increases drastically as ξ increases to 0.25. The hydrogen peroxide density in plasma activated water deceases, reaches its minimum value at ξ = 0.05, and then increases again, as ξ increases from a small value to a large value. The pH value of the plasma activated water, which is slightly changed to alkali without oxygen, decreases as ξ increases.

Enhancement of cellular glucose uptake by reactive species: a promising approach for diabetes therapy.

It is generally known that antidiabetic activity is associated with an increased level of glucose uptake in adipocytes and skeletal muscle cells. However, the role of exogenous reactive oxygen and nitrogen species (RONS) in muscle development and more importantly in glucose uptake is largely unknown. We investigate the effect of RONS generated by cold atmospheric plasma (CAP) in glucose uptake. We show that the glucose uptake is significantly enhanced in differentiated L6 skeletal muscle cells after CAP treatment. We also observe a significant increase of the intracellular Ca++ and ROS level, without causing toxicity. One of the possible reasons for an elevated level of glucose uptake as well as intracellular ROS and Ca++ ions is probably the increased oxidative stress leading to glucose transport.

Influence of Nitric Oxide generated through microwave plasma on L6 skeletal muscle cell myogenesis via oxidative signaling pathways.

Myogenic precursors are myoblasts that have a potency to differentiate into muscle fibers on injury and maintain the regenerative power of skeletal muscle. However, the roles of exogenous nitric oxide (NO) in muscle development and myoblast differentiation are largely unknown. Therefore, in this study, we examined the effects of exogenous NO generated by a microwave plasma torch on rat myoblastic L6 cell proliferation and differentiation. We observed that the differentiation of L6 myogenic precursor cells into myotubes was significantly enhanced after NO treatment. The expression of the myogenesis marker proteins and mRNA level, such as myoD, myogenin, and myosin heavy chain (MHC), as well as the cyclic guanosine monophosphate (cGMP) level, were significantly increased after the NO treatment, without creating toxicity. Moreover, we observed that the oxidative stress signaling [extracellular-signal-regulated kinase (Erks), and Adenosine monophosphate-activated protein kinase (AMPK)] phosphorylation was higher in NO treated cells than in the control cells [without NO treatment]. Therefore, these results reveal the exogenous NO role in regulating myoblast differentiation through the oxidative stress signaling pathway. Through this work, we can suggest that exogenous NO can help in cell differentiation and tissue regeneration, which provides new possibilities for plasma medicine.

Differential Inactivation of Fungal Spores in Water and on Seeds by Ozone and Arc Discharge Plasma.

Seed sterilization is essential for preventing seed borne fungal diseases. Sterilization tools based on physical technologies have recently received much attention. However, available information is very limited in terms of efficiency, safety, and mode of action. In this study, we have examined antifungal activity of ozone and arc discharge plasma, potential tools for seed sterilization. In our results, ozone and arc discharge plasma have shown differential antifungal effects, depending on the environment associated with fungal spores (freely submerged in water or infected seeds). Ozone inactivates Fusarium fujikuroi (fungus causing rice bakanae disease) spores submerged in water more efficiently than arc discharge plasma. However, fungal spores associated with or infecting rice seeds are more effectively deactivated by arc discharge plasma. ROS generated in water by ozone may function as a powerful fungicidal factor. On the other hand, shockwave generated from arc discharge plasma may have greatly contributed to antifungal effects on fungus associated with rice seeds. In support of this notion, addition of ultrasonic wave in ozone generating water has greatly increased the efficiency of seed disinfection.

A comparative study for the inactivation of multidrug resistance bacteria using dielectric barrier discharge and nano-second pulsed plasma.

Bacteria can be inactivated through various physical and chemical means, and these have always been the focus of extensive research. To further improve the methodology for these ends, two types of plasma systems were investigated: nano-second pulsed plasma (NPP) as liquid discharge plasma and an Argon gas-feeding dielectric barrier discharge (Ar-DBD) as a form of surface plasma. To understand the sterilizing action of these two different plasma sources, we performed experiments with Staphylococcus aureus (S. aureus) bacteria (wild type) and multidrug resistant bacteria (Penicillum-resistant, Methicillin-resistant and Gentamicin-resistant). We observed that both plasma sources can inactivate both the wild type and multidrug-resistant bacteria to a good extent. Moreover, we observed a change in the surface morphology, gene expression and ß-lactamase activity. Furthermore, we used X-ray photoelectron spectroscopy to investigate the variation in functional groups (C-H/C-C, C-OH and C=O) of the peptidoglycan (PG) resulting from exposure to plasma species. To obtain atomic scale insight in the plasma-cell interactions and support our experimental observations, we have performed molecular dynamics simulations to study the effects of plasma species, such as OH, H2O2, O, O3, as well as O2 and H2O, on the dissociation/formation of above mentioned functional groups in PG.

Effects of Mass Flow Rate on the Thermal-Flow Characteristics of Microwave CO2 Plasma.

In this study, the thermal-flow characteristics of atmospheric pressure microwave CO2 plasma were numerically investigated by simulation. The electric and gas flow fields in the reaction chamber with a microwave axial injection torch operated at 2.45 GHz were simulated. The microwave launcher had the standard rectangular waveguide WR340 geometry. The simulation was performed by using the COMSOL Multiphysics plasma model with various mass flow rates of CO2. The electric fields, temperature profiles and the density of electrons were graphically depicted for different CO2 inlet mass flow rates.

Generation mechanism of hydroxyl radical species and its lifetime prediction during the plasma-initiated ultraviolet (UV) photolysis.

Through this work, we have elucidated the mechanism of hydroxyl radicals (OH(•)) generation and its life time measurements in biosolution. We observed that plasma-initiated ultraviolet (UV) photolysis were responsible for the continues generation of OH(•) species, that resulted in OH(•) to be major reactive species (RS) in the solution. The density and lifetime of OH(•) species acted inversely proportional to each other with increasing depth inside the solution. The cause of increased lifetime of OH(•) inside the solution is predicted using theoretical and semiempirical calculations. Further, to predict the mechanism of conversion of hydroxide ion (OH(-)) to OH(•) or H2O2 (hydrogen peroxide) and electron, we determined the current inside the solution of different pH. Additionally, we have investigated the critical criterion for OH(•) interaction on cancer cell inducing apoptosis under effective OH(•) exposure time. These studies are innovative in the field of plasma chemistry and medicine.

Non-thermal plasma with 2-deoxy-D-glucose synergistically induces cell death by targeting glycolysis in blood cancer cells.

In this study, we show the selective and efficient anti-cancer effects of plasma (at a low dose) when cell metabolic modifiers are also included. 2-deoxy-D-glucose (2-DG), a glycolytic inhibitor, was used with effective doses of non-thermal plasma, synergistically attenuating cell metabolic viability and inducing caspase-dependent and independent cell death. The combination treatment decreased the intracellular ATP and lactate production in various types of blood cancer cells in vitro. Taken together, our findings suggest that 2-DG enhances the efficacy and selectivity of plasma and induces the synergistic inhibition of cancer cell growth by targeting glycolysis and apoptosis. Specifically, this treatment strategy demonstrated an enhanced growth inhibitory effect of plasma in the presence of a metabolic modifier that was selective against cancer cells, not non-malignant cells. This is the first study to report the advantage of combining plasma with 2-DG to eradicate blood cancer cells. Finally, we conclude that 2-DG with non-thermal plasma may be used as a combination treatment against blood cancer cells.

Photodynamic Anticancer Activity of CoFe2O4 Nanoparticles Conjugated with Hematoporphyrin.

This work reports the synthesis and the characterization of water-soluble and biocompatible photosensitizer (PS)-conjugated magnetic nanoparticles composed of a cobalt ferrite (CoFe2O4) magnetic core coated with a biocompatible hematoporphyrin (HP) shell. The photo-functional cobalt ferrite magnetic nanoparticles (CoFe2O4@HP) were uniform in size, stable against PS leaching, and highly efficient in the photo-generation of cytotoxic singlet oxygen under visible light. With the CoFe2O4@HP, we acquired in vitro MR images of cancer cells (PC-3) and confirmed good biocompatibility of the CoFe2O4@HP in both normal and cancer cells. In addition, we confirmed the potential of the CoFe2O4@HP as an agent for photodynamic therapy (PDT) applications. The photodynamic anticancer activities in 25, 50, and 100 µg/mL of CoFe2O4@HP were measured and found to exceed 99% (99.0, 99.4, and 99.5%) (p < 0.002). The photodynamic anticancer activity was 81.8% (p < 0.003). From these results, we suggest that our CoFe2O4@HP can be used safely as a type of photodynamic cancer therapy with potential as a therapeutic agent having good biocompatibility. Moreover, these photo-functional magnetic nanoparticles are highly promising for applications in versatile imaging diagnosis and as a therapy tool in biomedical engineering.

Induced apoptosis in melanocytes cancer cell and oxidation in biomolecules through deuterium oxide generated from atmospheric pressure non-thermal plasma jet.

Recently, atmospheric-pressure non-thermal plasma-jets (APPJ) are being for the cancer treatment. However, APPJ still has drawbacks such as efficiency and rise in temperature after treatment. So, in this work, a synergetic agent D2O vapour is attached to APPJ which not only increase the efficiency of plasma source against cancer treatment, but also controlled the temperature during the treatment. OD generated by the combination of D2O + N2 plasma helped in enhancing the efficiency of APPJ. We observed OD induced apoptosis on melanocytes G361 cancer cells through DNA damage signalling cascade. Additionally, we observed that plasma induces ROS, which activated MAPK p38 and inhibits p42/p44 MAPK, leading to cancer cell death. We have also studied DNA oxidation by extracting DNA from treated cancer cell and then analysed the effects of OD/OH/D2O2/H2O2 on protein modification and oxidation. Additionally, we attempted molecular docking approaches to check the action of D2O2 on the apoptosis related genes. Further, we confirmed the formation of OD/OH simultaneously in the solution using optical emission spectroscopy. Moreover, the simultaneous generation of D2O2/H2O2 was detected by the use of confocal Raman spectroscopy and density measurements.

Influence of nanosecond pulsed plasma on the non-enzymatic pathway for the generation of nitric oxide from L-arginine and the modification of graphite oxide to increase the solar cell efficiency.

In this work, we demonstrated the action of nanosecond pulsed plasma (NPP) on the generation of nitric oxide (NO) from the non-enzymatic pathway and on the modification of graphite oxide (GO) sheets to increase polymer solar cells (PSCs) efficiency. NO is an important signal and an effector molecule in animals, which is generated from the enzyme-catalyzed oxidation of L-arginine to NO and L-citrulline. Hence, L-arginine is an important biological precursor for NO formation. Therefore, we developed a new non-enzymatic pathway for the formation of NO and L-citrulline using NPP and characterized the pathway using NO detection kit, NMR, liquid chromatography/capillary electrophoresis-mass spectrometry (LC/CE-MS) for both quantitative and qualitative bioanalysis. We then synthesized and modified the functional groups of GO using NPP, and it was characterised by X-ray photoelectron spectroscopy (XPS), confocal Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) imaging, cathodoluminescence (CL) and work function using γ-FIB. Further, we also tested the power conversion efficiency of the PSCs devices with modified GO that is similar to the one obtained with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) as HTL. This work is perceived to have great implications for inexpensive and efficient methodology for NO generation and modification of GO, which are applicable in materials from nanomaterials to biomolecules.

Non-thermal plasma treatment diminishes fungal viability and up-regulates resistance genes in a plant host.

Reactive oxygen and nitrogen species can have either harmful or beneficial effects on biological systems depending on the dose administered and the species of organism exposed, suggesting that application of reactive species can possibly produce contradictory effects in disease control, pathogen inactivation and activation of host resistance. A novel technology known as atmospheric-pressure non-thermal plasma represents a means of generating various reactive species that adversely affect pathogens (inactivation) while simultaneously up-regulating host defense genes. The anti-microbial efficacy of this technology was tested on the plant fungal pathogen Fusarium oxysporum f.sp. lycopersici and its susceptible host plant species Solanum lycopercicum. Germination of fungal spores suspended in saline was decreased over time after exposed to argon (Ar) plasma for 10 min. Although the majority of treated spores exhibited necrotic death, apoptosis was also observed along with the up-regulation of apoptosis related genes. Increases in the levels of peroxynitrite and nitrite in saline following plasma treatment may have been responsible for the observed spore death. In addition, increased transcription of pathogenesis related (PR) genes was observed in the roots of the susceptible tomato cultivar (S. lycopercicum) after exposure to the same Ar plasma dose used in fungal inactivation. These data suggest that atmospheric-pressure non-thermal plasma can be efficiently used to control plant fungal diseases by inactivating fungal pathogens and up-regulating mechanisms of host resistance.

Optical and structural properties of plasma-treated ZnO nanostructures.

We studied the effect of plasma treatment on the structural and optical properties of ZnO nanostructures prepared by chemical bath deposition in an aqueous solution of Zn(NO3)2 and hexamethylenetetramine. The room-temperature photoluminescence (PL) spectrum of the as-grown ZnO nanostructures exhibited two emission bands due to exciton emission and defect emission. After treating with hydrogen plasma, the treated ZnO nanostructures exhibited stronger exciton emission than the as-grown, untreated ZnO nanostructures in their respective cathodoluminescence and PL spectra. The low-temperature PL spectrum of the hydrogen plasma-treated ZnO nanostructures showed a strong exciton emission at 3.34 eV, attributing to the bound exciton and its longitudinal optical-phonon sidebands. The strong exciton emission is thought to be due to the combined effect of exciton emission enhancement by defect passivation and optical confinement resulting from nanostructure geometry.

Effects of background fluid on the efficiency of inactivating yeast with non-thermal atmospheric pressure plasma.

Non-thermal plasma at atmospheric pressure has been actively applied to sterilization. However, its efficiency for inactivating microorganisms often varies depending on microbial species and environments surrounding the microorganisms. We investigated the influence of environmental factors (surrounding media) on the efficiency of microbial inactivation by plasma using an eukaryotic model microbe, Saccharomyces cerevisiae, to elucidate the mechanisms for differential efficiency of sterilization by plasma. Yeast cells treated with plasma in water showed the most severe damage in viability and cell morphology as well as damage to membrane lipids, and genomic DNA. Cells in saline were less damaged compared to those in water, and those in YPD (Yeast extract, Peptone, Dextrose) were least impaired. HOG1 mitogen activated protein kinase was activated in cells exposed to plasma in water and saline. Inactivation of yeast cells in water and saline was due to the acidification of the solutions by plasma, but higher survival of yeast cells treated in saline may have resulted from the additional effect related to salt strength. Levels of hydroxyl radical (OH·) produced by plasma were the highest in water and the lowest in YPD. This may have resulted in differential inactivation of yeast cells in water, saline, and YPD by plasma. Taken together, our data suggest that the surrounding media (environment) can crucially affect the outcomes of yeast cell plasma treatment because plasma modulates vital properties of media, and the toxic nature of plasma can also be altered by the surrounding media.