Cold Helium Plasma Research Articles

How does atmospheric pressure cold helium plasma affect the biomechanical behaviour on alkali-lesioned corneas?

BackgroundMelting corneal ulcers are a serious condition that affects a great number of animals and people around the world and it is characterised by a progressive weakening of the tissue leading to possible severe ophthalmic complications, such as visual impairment or blindness. This disease is routinely treated with medical therapy and keratoplasty, and recently also with alternative regenerative therapies, such as cross-linking, amniotic membrane transplant, and laser. Plasma medicine is another recent example of regenerative treatment that showed promising results in reducing the microbial load of corneal tissue together with maintaining its cellular vitality. Since the effect of helium plasma application on corneal mechanical viscoelasticity has not yet been investigated, the aim of this study is first to evaluate it on ex vivo porcine corneas for different exposition times and then to compare the results with previous data on cross-linking treatment.Results94 ex vivo porcine corneas divided into 16 populations (healthy or injured, fresh or cultured and treated or not with plasma or cross-linking) were analysed. For each population, a biomechanical analysis was performed by uniaxial stress-relaxation tests, and a statistical analysis was carried out considering the characteristic mechanical parameters. In terms of equilibrium normalised stress, no statistically significant difference resulted when the healthy corneas were compared with lesioned plasma-treated ones, independently of treatment time, contrary to what was obtained about the cross-linking treated corneas which exhibited more intense relaxation phenomena.ConclusionsIn this study, the influence of the Helium plasma treatment was observed on the viscoelasticity of porcine corneas ex vivo, by restoring in lesioned tissue a degree of relaxation similar to the one of the native tissue, even after only 2 min of application. Therefore, the obtained results suggest that plasma treatment is a promising new regenerative ophthalmic therapy for melting corneal ulcers, laying the groundwork for further studies to correlate the mechanical findings with corneal histology and ultrastructural anatomy after plasma treatment.

Effect of Intermittent Low-Pressure Radiofrequency Helium Cold Plasma Treatments on Rice Gelatinization, Fatty Acid, and Hygroscopicity.

To establish the safe and reproducible effects of cold plasma (CP) technology on food products, this study evaluated the gelatinization parameters, fatty acid profile, and hygroscopic properties of rice grains repeatedly treated with low-pressure radiofrequency (RF) helium CP (13.56 MHz, 140 Pa, 120 W-20s, 0-4 times, and 300 g sample). Compared with the untreated (zero times) sample, with an increase in CP treatment times from one to four on rice, the water contact angle and cooking time decreased, while the water absorption rate and freshness index increased, and the pH value remained unchanged. CP repeating treatments essentially had no effect on the gelatinization enthalpy, but significantly increased the peak temperature of gelatinization. From the pasting profile of rice that has been repeatedly CP treated, the peak, breakdown, and setback viscosities in flour paste decreased. CP repeating treatments on rice did not change the short-range molecular order of starch. Compared with the untreated sample, the first helium CP treatment maintained the content of C18:1n9c, C18:2n6c, and C18:3n3, but the second to fourth CP treatment significantly decreased contents of these fatty acids (FAs) as the C18:0 content increased. The first three CP treatments can increase the water and sucrose solvent retention capacity in rice flours. CP repeatedly treated rice first exhibits the similar monolayer water content and solid surface area of water sorption. Principal component analysis shows that contact angle, pasting parameters, and fatty acid profile in milled rice are quite sensitive to CP treatment. Results support that the effect of low-pressure RF 120W helium CP treatment 20 s on rice grains is perdurable, and the improvement of CP intermittent treatments on rice cooking and pasting properties is an added benefit, and the hygroscopic properties of rice was kept.

Modeling of the ion in cold helium plasma II: transport properties of in helium

A detailed modeling of N transport properties in helium gas has been performed by employing Monte Carlo calculations based on ab initio collision cross-sections reported by our group in a preceding paper (S Paláček et al 2022 Plasma Sources Sci. Technol. 31 105004). A broad range of the reduced electric field () is considered to provide data directly usable in macroscopic modeling of processes in cold helium plasmas. The N mobility in helium gas at room temperature (T = 300 K), the characteristic energies of its longitudinal and transversal diffusion, and the rate constant of the N dissociation induced by collisions with helium atoms have been calculated. The effect of the N initial rotational-vibrational excitation is investigated as well as the effect of the rotational alignment of the N molecule. A direct comparison with N/He mobility experimental data is performed as well as indirect tests of theoretical estimates of the characteristic diffusion energies by comparing the latter with pseudo-experimental data obtained from mobility experiments via an inverse-method approach.

Cold Plasma Pretreatment Promoting Penicillin Accumulation in Penicillium Chrysogenum

Penicillin is the most important class of β-lactam antibiotics. The improvement of high-yielding strain has always been the focus of low-cost industrial production. In this study, Penicillium chrysogenum CICC 40654 was pretreated by helium cold plasma, and then used for fermentation to synthesize penicillin. Through single factor test and orthogonal one, the optimal values of pretreatment parameters such as discharge power, discharge time and helium working pressure were discussed. Results showed that the strain pretreated at 130 W and 100 Pa for 35 s had the highest penicillin synthesis (more than 30 μg/g dried mycelium biomass) on fermentation for 3 days, which was about 79.7% higher than that of the control. In summary, green and efficient cold plasma pretreatment enhanced its ability of penicillin accumulation of Penicillium chrysogenum. This study will provide a new methodological basis for improving industrial strains for high-yield biomedicine.

Effects of Air and Helium Cold Plasma on Sensory Acceptability and Quality of Fresh Sea Bass (Dicentrarchus labrax)

Effects of Air and Helium Cold Plasma on Sensory Acceptability and Quality of Fresh Sea Bass (Dicentrarchus labrax)

Modeling of the ion in cold helium plasma: dynamics of collisions and cross-sections

A detailed dynamical study is presented for /He collisions running in the electronic ground state of the collision complex. Hybrid, quantum–classical dynamical calculations have been performed considering a broad range of collision energies (E coll = 0.01–100 eV) and various initial rotational–vibrational excitations of the ion. Both non-reactive and reactive ( collision-induced dissociation) cross-sections have been calculated with the momentum-transfer approximation applied to the former ones. A thorough comparison with pseudo-experimental data obtained from mobility measurements reported in the literature via an inverse-method approach has been performed and the effect of the rotational alignment of the ion on calculated cross-sections has been assessed and analyzed.

THE EFFECT OF GAS FLOWS OF VARIOUS DEGREES OF IONIZATION ON THE DIELECTRIC PARAMETERS OF BLOOD IN VITRO

The aim of the study was to evaluate the dielectric properties of blood when treated with various ionized and non-ionized gas streams.
 Material and methods. The effects of gas flows were studied on 10 whole blood samples of practically healthy volunteers divided into 5 portions (control, treatment with helium, argon and cold plasma obtained from them for 1 min.). The dielectric properties of the biological fluid were studied by microwave dielectrometry on the permeability and conductivity of the biological fluid.
 Results. It was revealed that the presence of ionization and the type of carrier gas directly determine the nature of their effect on a model biological object (whole blood). It has been found that non-ionized helium and argon fluxes increase the permeability of the biological fluid without affecting its conductivity. On the contrary, ionized flows demonstrate more pronounced and specific shifts in the dielectric characteristics of blood. Helium cold plasma significantly increases the conductivity of the biological fluid while maintaining its conductivity, and argon plasma reduces both studied indicators.

The Effect of Cold Helium Plasma on Microcirculation in the Periwound Zone after Experimental Thermal Injury

The Effect of Cold Helium Plasma on Microcirculation in the Periwound Zone after Experimental Thermal Injury

A Prospective, Randomised, Controlled, Split-Face Clinical Trial to Assess the Safety and the Efficacy of Cold Atmospheric Plasma in the Treatment of Acne Vulgaris

The increase in antibiotic resistance requires effective non-antibiotic therapies for acne. Cold atmospheric plasma (CAP) inactivates bacteria and improves wound healing, but its effect on acne has not been investigated. The objective of this controlled split-face study was to assess safety and efficacy of CAP in moderate acne. One side of the face received 8–10 treatments with cold helium plasma within 4–6 weeks; follow-up was two and four weeks thereafter. Acne lesions were counted, followed by global acne severity ratings. Of the 34 patients included, 29 completed the study. No serious adverse events occurred. The two facial sides did not significantly differ in the number of inflammatory and non-inflammatory lesions. An interaction effect of number and type of treatment was found for inflammatory lesions. Lesion reduction after 10 treatments was significantly higher on the treated than on the untreated side. Percentage of patients reporting improved aesthetics was higher for the treated than for the untreated side after treatment completion (79% vs. 45%) and at the two- (72% vs. 45%) and four-week follow-up (79% vs. 52%). In conclusion, CAP was safe with excellent tolerability, showed moderate reduction in acne lesions and led to higher patient-based ratings of aesthetics than non-treatment.

Cold helium plasma jet does not stimulate collagen remodeling in a 3D human dermal substitute

Cold Atmospheric Plasma (CAP) is an emerging physical approach displaying encouraging antitumor and wound healing effects both in vitro and in vivo. In this study, we assessed the potential of direct CAP to remodel skin collagens using an original tissue-engineered human dermal substitute model rich in endogenous extracellular matrix (ECM) covered with 600 µl of culture medium and treated with CAP for 30 and 120 s. Our results indicated that Reactive Oxygen and Nitrogen Species (RONS) such as H2O2, NO3– and NO2– were produced in the medium during treatment. It appeared that in the CAP-treated dermal substitutes 1) cell viability was not altered, 2) pro-collagen I secretion was not modified over 48 h of culture after treatment, 3) global activity of matrix metalloproteinases MMPs was not modulated over 48 h after treatment, and 4) no change in hydroxyproline content was observed over 5 days after treatment. In order to confirm the efficiency of our device, we showed that the plasma-activated culture medium induced cell apoptosis and growth delay using a 3D human tumor spheroid model. In conclusion, no effect of direct CAP treatment was monitored on dermal ECM production and degradation, indicating that CAP does not stimulate collagen remodeling at the tissue scale.

Development of non-thermal atmospheric plasma torch utilizing high voltage power supply

In this paper, we report the successful development of non-thermal atmospheric plasma torch employing high voltage power supply. Usually atmospheric plasma is generated at high temperature (>1000 °C) and it is quite a challenge to generate cold plasma (<150 °C). The plasma torch in this assembly uses helium gas. The length of helium plasma glow discharge in this research is studied and optimized, with flow rate varied from 2 to 7 liters per mins, at varied applied voltage of 1.20 to 2.00 kV. The generated cold helium plasma has tunable length of around 5 to 35 mm, as cold as 26 °C. The plasma setup in this study is projected to be suitable for future applications in several fields such as industrial wastewater processing, as well as food processing, or agricultural field.

Cold helium plasma as a modifier of free radical processes in the blood: in vitro study

We studied the influence of various exposures (1, 2, 3, 5, 10 and 15 min.) effects of cold helium plasma on the state of free radical processes in the biological fluid (human blood). It was found that the nature of the response of antioxidant systems of blood to cold plasma treatment is directly determined by exposure, as evidenced by the results of chemiluminescence assessment of the intensity of free radical processes and total antioxidant activity, as well as the dynamics of the concentration of malonic dialdehyde. At the same time, the short-term processing mode of biological fluid allows us to establish the presence of a two-phase influence of the factor on oxidative processes (“the phenomenon of the antioxidant window”).

Inactivation of Salmonella on black peppercorns using an integrated ultraviolet-C and cold plasma intervention

A nonthermal process that applies ultraviolet (UV)–C and helium cold plasma (CP) simultaneously (UV-CP) has been investigated as an intervention technology to inactivate Salmonella on black peppercorns. The optimum CP treatment voltage and UV-CP treatment time for inactivating Salmonella on black peppercorns were predicted using a model equation as 9.7 kV and 22.1 min, respectively, which non-thermally inactivated Salmonella by 3.7 log CFU/g. UV-CP treatment yielded a stronger bactericidal activity than UV treatment alone, without inducing photoreactivation. In addition, UV-CP-induced reactive species were similar to those found in individual UV and CP treatments. Furthermore, UV-CP treatment caused a profound deformation of Salmonella morphology and a greater extent of DNA damage than UV or CP treatment did alone. UV-CP treatment did not alter the color or 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity; however, it lowered the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and piperine concentration in the peppercorns. The findings of this study demonstrate the potential application of UV-CP treatment for decontamination of black peppercorns.

Effect of cold helium plasma on the catalytic activity of certain erythrocyte dehydrogenases of rat blood

The work is aimed at clarifying the effect of cold helium plasma on the catalytic properties of lactate- and aldehyde dehydrogenase in rat blood erythrocytes. The effect was studied in 20 white Wistar rats. Upon completion of the full course of exposures (1 exposure per day for 5 days), blood samples were taken from all animals with subsequent erythrocyte isolation performed by standard differential centrifugation for assessing the activity of lactate dehydrogenase (LDH) and aldehyde dehydrogenase (AlDH). When assessing LDH activity, both direct and reverse reactions were considered. Gas flow microwave ionisation was applied to the synthesis of cold plasma using a special device developed at the Institute of Applied Physics, Russian Academy of Sciences. The plasma treatment was established to provide stimulation of LDH activity in both direct and reverse reactions. In the direct reaction, erythrocytic LDH activity in rats with plasma-treated skin almost doubled (94 %) against 48 % of activity growth in the reverse reaction. Rat blood erythrocyte AlDH tends to moderate inactivation, with catalytic properties observed to decrease by 13 %. Thus, treating the skin of healthy rats with cold helium plasma was demonstrated to stimulate the energy metabolism of blood cells, with moderate activity inhibition for AlDH presenting one of the detoxification enzymes. The nature of the observed shifts indicates their adaptability. In general, according to the obtained data, the modulation of free radical processes was confirmed to play a key role in the molecular-cellular mechanisms of the cold helium plasma action on the biological system.

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.

Efficacy of cavity liners with/without atmospheric cold helium plasma jet for dentin remineralization

Aim: This study aimed to assess the efficacy of cavity liners with/without the atmospheric cold plasma jet (ACPJ) for dentin remineralization. Material and methods The occlusal third of 24 extracted third molars was cut. An occlusal cavity was prepared in the dentin of each tooth with 1 mm depth and 2 mm diameter and demineralized with 37% phosphoric acid for 1 min. The teeth were randomly divided into 8 groups (n = 3). The first control group only underwent demineralization with phosphoric acid. The second control group underwent demineralization and helium plasma jet. Groups 3 to 5 were filled with calcium hydroxide (CH), RetroMTA (MTA) and Biodentine. Groups 6 to 8 were subjected to ACPJ, and all the groups were sealed with polycarboxylate. After 2 weeks of immersion in water, the teeth were longitudinally sectioned and their mineral content was analyzed using energy-dispersive X-ray spectroscopy (EDX). Results The interaction effect of ACPJ and type of liner was not significant (p > 0.05). Application of ACPJ in combination with liner had a significant effect on calcium and phosphorous contents (p < .05). The calcium and phosphorous contents in the control groups were significantly lower than other groups (p < .05). The calcium and phosphorous contents in the CH group were higher than the control but significantly lower than the MTA and Biodentine groups. The values in the MTA and Biodentine groups were the same and higher than other groups. Conlusion All three cavity liners significantly increased the calcium and phosphorous contents of dentin. This increase was significantly greater by the MTA and Biodentine and enhanced by the ACPJ.

Estimation of the Microcirculatory Response to the Effect of Cold Helium Plasma

Abstract—This study was aimed at estimating the microcirculatory response to local application of cold helium plasma. Experiments were performed with 20 healthy male Wistar rats, which were divided into two groups of 10 rats each. Rats of one (control) group (n = 10) were tested once for microcirculatory indices. Rats of the other (test) group (n = 10) were treated daily with cold helium plasma for 5 days. Plasma was applied to the surface of the skin on the back; the duration of the exposure was 1 min. Cold helium plasma was generated with a special device, which was designed and constructed at the Institute of Applied Physics (Nizhny Novgorod, Russia) and utilized microwave-induced ionization of gas flow. Microcirculation was tested by laser Doppler flowmetry, using an LAKK-M device (Moscow, Russia). A short course (five daily procedures) of cold helium plasma treatment moderately decreased the intensity of blood flow through small vessels. The effect was associated with nitric oxide-dependent vasodilation and optimization of the role that bypass mechanisms play in microcirculation. Cold helium plasma treatment was assumed to exert a proadaptive hemodynamic effect.

Effects of Helium Cold Plasma on Erythrocyte Metabolism.

The effects of helium cold plasma on some parameters of metabolism of rat erythrocytes were studied after a course exposure (10 daily procedures, 1 min each). The intensity of free-radical processes in erythrocyte membranes, malondialdehyde concentration, and aldehyde dehydrogenase activity were analyzed. The exposure to helium cold plasma led to a significant increase in malondialdehyde level mostly associated with inhibition of its utilization. These changes were not related to activation of malondialdehyde synthesis in LPO reactions.

Sorption equilibrium moisture and isosteric heat of cold plasma treated milled rice

Abstract To promote industrial adoption of cold plasma as a sustainable and safe processing technology for rice, data on equilibrium moisture content (EMC) for cold plasma treated milled rice of five Chinese varieties were collected by a gravimetric method at 11–96% equilibrium relative humidity (ERH) and a temperature range of 15–35 °C. Nine models were fitted well to the sorption data, with the modified Guggenheim–Anderson–deBoer equation (3-MGAB), modified Henderson equation (MHE), and a polynomial equation being the best fits. At a constant ERH, the EMC was negatively correlated with temperature, whereas there was a strong effect of temperature on the sorption isotherms of the milled rice. Initially, the isosteric heats of sorption for the cold plasma treated rice decreased rapidly with increasing sample moisture content (MC); however, when MC was higher than 15% of the wet basis (w.b.), further increases in MC caused a slight decrease in heat sorption values. The heat of vaporization of the milled rice approached the latent heat of pure water at a moisture content of ~17.5% w.b., which was ~2500 kJ/kg. The isosteric heat of sorption values of the milled rice predicted by the modified Chung-Pfost equation (MCPE) and MHE models negatively correlated with temperature. At 70% ERH, the safe-storage MC of the cold plasma treated rice were ≤14.5% w.b. at 25 °C. In comparison to the untreated milled rice, the cold plasma treated rice with 120 W for 20 s and 60 s significantly decreased the water contact angle and increased kernel broken index, without significantly changing the appearance quality of milled rice. The cold plasma treated rice with 120 W-20 s had insignificantly higher EMC than that of 120 W-60 s at the studied temperature range. This study demonstrates that helium cold plasma treatment insignificantly changed hygroscopic property of milled rice whilst maintaining the appearance quality.

Cold plasma poration and corrugation of pumpkin seed coats

The treatment of seeds and plants by electrically generated cold atmospheric pressure plasma can accelerate seed germination and radicle growing rates. The plasma generated reactive oxygen and nitrogen species, UV photons, and high frequency electromagnetic fields can penetrate into seed coats and modify their surface properties. Atomic force microscope data shows that cold helium or argon plasma induces strong corrugation of pumpkin seed coats, produces pores and surface defects. These structural deformations and poration enhance water uptake by seeds during the imbibing process, accelerate seeds germination, and increase seed growth. The cold atmospheric pressure plasmas treatment of pumpkin seeds also decreases the apparent contact angle between a water drop and the seed surface, thereby improving the wetting properties of seeds surfaces. Magnetic resonance imaging studies show acceleration of water uptake in pumpkin seeds exposed to a cold plasma jet. Reactive nitrogen and oxygen species, high frequency electromagnetic fields and photons emitted by the plasma jets accelerate germination of pumpkin seeds both independently and synergistically. These results show that cold plasma can be used in agriculture for acceleration of seed germination, increasing growth of plants seedlings, poration and corrugation of the bio-tissue surfaces.