Cold Atmospheric Pressure Plasma Treatment Research Articles

Repeated exposure of the oral mucosa over 12\xa0months with cold plasma is not carcinogenic in mice

Peri-implantitis may result in the loss of dental implants. Cold atmospheric pressure plasma (CAP) was suggested to promote re-osseointegration, decrease antimicrobial burden, and support wound healing. However, the long-term risk assessment of CAP treatment in the oral cavity has not been addressed. Treatment with two different CAP devices was compared against UV radiation, carcinogen administration, and untreated conditions over 12 months. Histological analysis of 406 animals revealed that repeated CAP exposure did not foster non-invasive lesions or squamous cell carcinoma (SCCs). Carcinogen administration promoted non-invasive lesions and SCCs. Molecular analysis by a qPCR screening of 144 transcripts revealed distinct inflammatory profiles associated with each treatment regimen. Interestingly, CAP treatment of carcinogen-challenged mucosa did not promote but instead left unchanged or reduced the proportion of non-invasive lesions and SCC formation. In conclusion, repeated CAP exposure of murine oral mucosa was well tolerated, and carcinogenic effects did not occur, motivating CAP applications in patients for dental and implant treatments in the future.

Combining Biocompatible and Biodegradable Scaffolds and Cold Atmospheric Plasma for Chronic Wound Regeneration.

Skin regeneration is a quite complex process. Epidermal differentiation alone takes about 30 days and is highly regulated. Wounds, especially chronic wounds, affect 2% to 3% of the elderly population and comprise a heterogeneous group of diseases. The prevailing reasons to develop skin wounds include venous and/or arterial circulatory disorders, diabetes, or constant pressure to the skin (decubitus). The hallmarks of modern wound treatment include debridement of dead tissue, disinfection, wound dressings that keep the wound moist but still allow air exchange, and compression bandages. Despite all these efforts there is still a huge treatment resistance and wounds will not heal. This calls for new and more efficient treatment options in combination with novel biocompatible skin scaffolds. Cold atmospheric pressure plasma (CAP) is such an innovative addition to the treatment armamentarium. In one CAP application, antimicrobial effects, wound acidification, enhanced microcirculations and cell stimulation can be achieved. It is evident that CAP treatment, in combination with novel bioengineered, biocompatible and biodegradable electrospun scaffolds, has the potential of fostering wound healing by promoting remodeling and epithelialization along such temporarily applied skin replacement scaffolds.

Cold Atmospheric Pressure Plasma Treatment of Maize Grains-Induction of Growth, Enzyme Activities and Heat Shock Proteins.

Zea mays L. is one of the most produced crops, and there are still parts of the world where maize is the basic staple food. To improve agriculture, mankind always looks for new, better methods of growing crops, especially in the current changing climatic conditions. Cold atmospheric pressure plasma (CAPP) has already showed its potential to enhance the culturing of crops, but it still needs more research for safe implementation into agriculture. In this work, it was shown that short CAPP treatment of maize grains had a positive effect on the vitality of grains and young seedlings, which may be connected to stimulation of antioxidant and lytic enzyme activities by short CAPP treatment. However, the prolonged treatment had a negative impact on the germination, growth, and production indexes. CAPP treatment caused the increased expression of genes for heat shock proteins HSP101 and HSP70 in the first two days after sowing. Using comet assay it was observed that shorter treatment times (30–120 s) did not cause DNA damage. Surface diagnostics of plasma-treated grains showed that plasma increases the hydrophilicity of the surface but does not damage the chemical bonds on the surface.

Design and characterisation of jet cold atmospheric pressure plasma and its effect on Escherichia coli, colour, pH, and bioactive compounds of sour cherry juice

SummaryA new system for cold atmospheric pressure plasma (CAPP) generation was designed and characterised. The effects of voltage (10, 15, 20 kV), frequency (10, 15, 20 kHz), gas flow rate (3, 5, 7 L min−1) and percentage of oxygen (0%, 0.5%, 1%) on the plasma jet length (PJL) were investigated. Then, different volumes (5, 10, 15 mL) of sour cherry juice were treated by CAPP to compare their physicochemical properties (colour and pH), Escherichia coli count, and bioactive compounds with samples treated by the conventional process. According to the results, PJL was increased by increasing the voltage and frequency and then remained constant. Also, PJL increases and then decreases by increasing the gas flow rate. Furthermore, CAPP treatment reduced E. coli count but did not alter the colour and pH of samples. Moreover, increasing the voltage, plasma treatment duration, and oxygen percentage enhanced the inactivation of E. coli. The best sterilisation effect was 6‐log cycle decrease in E. coli count which was achieved at a voltage of 19.6 kV, an oxygen concentration of 1%, and a gas flow rate of 4.5 L min−1. Besides, the total phenol content of juice was 277 GAE/100 g and was changed to 279 and 359 after plasma treatment and conventional process, respectively.

Simulation of the improvement in the performance of a silver-based surface plasmon resonance biosensor using experimental results of cold plasma treatment of glass substrate

In this study, the effect of observed pinholes in the Field emission scanning electron microscopy (FESEM) images on the performance of a silver-based surface plasmon resonance (SPR) biosensor is designed and analytically investigated by a finite element method using COMSOL multiphysics. The simulation results show that the sensitivity and figure of merit (FOM) enhancement of biosensor is attributed to the cold atmospheric-pressure plasma (CAP) treatment of glass substrate before deposition; leading to the omission of pinholes. This work is proposing a new way for SPR biosensors development using surface quality control of the deposited thin films with CAP treatment.

Multimodal Imaging Techniques to Evaluate the Anticancer Effect of Cold Atmospheric Pressure Plasma.

Simple SummarySkin cancer still poses a great burden for patients. One of the most promising therapy approaches in recent years is cold atmospheric pressure plasma. The aim of the study was to assess in vivo the effect of cold atmospheric pressure plasma on human squamous cell carcinoma as well as malignant melanoma tumour cell lines in a longitudinal and non-invasive manner with multimodal imaging techniques such as MRI and [18F]FDG PET. By using these techniques and chemiluminescence imaging, we present in the current study that reactive species increase in vivo upon treatment with cold plasma and consequently decrease tumour growth. Therefore, we propose cold atmospheric pressure plasma may be a potential adjuvant therapy option to established standard therapies of skin cancer.Background: Skin cancer is the most frequent cancer worldwide and is divided into non-melanoma skin cancer, including basal cell carcinoma, as well as squamous cell carcinoma (SCC) and malignant melanoma (MM). Methods: This study evaluates the effects of cold atmospheric pressure plasma (CAP) on SCC and MM in vivo, employing a comprehensive approach using multimodal imaging techniques. Longitudinal MR and PET/CT imaging were performed to determine the anatomic and metabolic tumour volume over three-weeks in vivo. Additionally, the formation of reactive species after CAP treatment was assessed by non-invasive chemiluminescence imaging of L-012. Histological analysis and immunohistochemical staining for Ki-67, ApopTag®, F4/80, CAE, and CD31, as well as protein expression of PCNA, caspase-3 and cleaved-caspase-3, were performed to study proliferation, apoptosis, inflammation, and angiogenesis in CAP-treated tumours. Results: As the main result, multimodal in vivo imaging revealed a substantial reduction in tumour growth and an increase in reactive species after CAP treatment, in comparison to untreated tumours. In contrast, neither the markers for apoptosis, nor the metabolic activity of both tumour entities was affected by CAP. Conclusions: These findings propose CAP as a potential adjuvant therapy option to established standard therapies of skin cancer.

Physical modification of Lepidium perfoliatum seed gum using cold atmospheric-pressure plasma treatment

In the present study, cold atmospheric-pressure plasma treatments (5 and 10 kV for 4–20 min) were used for the modification of Lepidium perfoliatum seed gum (LPSG). The content of carbonyl and carboxyl groups, as well as the water-solubility of LPSG increased after the plasma treatments; however, the numbers of surface hydroxyl groups decreased when 5kVplasma was used. Molecular weight and polydispersity index of LPSG significantly increased after exposure to the air plasma at 5 kV, whereas a significant decrease in molecular weight and a significant increase in polydispersity was observed with increase in the plasma voltage and treatment time. The molecular conformation of LPSG changed to a more disordered or less ordered form when higher plasma voltage was used. Results demonstrated that cleavage of C–O–C as well as formation of C–O–C bonds occurred during plasma treatments. The elastic components were always higher than the viscous one meaning that all native LPSG and modified gums dispersions had weak gel characteristics. However, plasma treated gums at 5 kV had stronger intertwined network than the native gum. Meanwhile, the viscoelasticity of treated LPSG at 10 kV was weaker than the native one. All modified and unmodified LPSGs dispersions revealed pseudoplastic flow behavior. 5 kV treated samples displayed higher apparent viscosity, while lower values of apparent viscosity was achieved after plasma treatments at 10 kV. Therefore, this study confirms the eminent ability of cold plasma as a means to modify or modulate food polysaccharides properties.

Effects of Extraction Conditions on Banana Peel Polyphenol Oxidase Activity and Insights into Inactivation Kinetics Using Thermal and Cold Plasma Treatment.

The objective of this work was to characterize banana peel polyphenol oxidase (PPO) and to study the inactivation kinetics during thermal and cold atmospheric pressure plasma treatment. Since varietal differences in enzyme characteristics are a well-known phenomenon, ‘Prata’ banana peel PPO was characterized, and PPO activity and thermal stability of the peel PPO of the two dessert banana cultivars ‘Cavendish’ and ‘Prata’ were compared to identify the cultivar better suited for industrial food applications. A crude extract obtained from the peels of the Brazilian banana variety ‘Prata’ revealed highest PPO activities (46.0–55.2 nkat/mL) at 30–40 °C in a range of pH 6.0–6.5 after addition of 0.5 g/gsample polyvinylpyrrolidone and 0.5% (v/v) Triton X-100 during extraction. ‘Cavendish’ PPO activity was four times higher. Banana peel PPO exhibited the highest affinity towards dopamine (KM = 0.94 mM). Thermal inactivation of ‘Prata’ and ‘Cavendish’ PPO was achieved at 90 °C after 5 and 15 min, respectively, whereas cold plasma treatment did not decrease PPO activity below 46% of the initial enzyme activity. The inactivation behavior of PPO could successfully be described by a two-fraction model indicating at least two types of isoenzymes with different thermal stability. The overall high thermal stability was mainly attributed to membrane-bound PPO. The results may help to prevent enzymatic browning of banana peels and thereby facilitate their valorization as food ingredients.

Inactivation of Listeria monocytogenes and Salmonella on Stainless Steel by a Piezoelectric Cold Atmospheric Plasma Generator

Cold atmospheric pressure plasma (CAP) is a novel non-thermal technology that is gaining increasing importance as a decontamination method. Stainless steel is a widespread food contact surface used in food-processing environments. In this study, for the first time, a low-voltage piezoelectric CAP device that uses ambient air was assessed for its antimicrobial efficiency against Salmonella and Listeria monocytogenes. These inoculated on stainless steel at different exposure times (0–300 s), two different distances (10 and 20 mm), and two different cleanliness levels (clean and protein-soiled). Two inactivation models were compared to study the inactivation kinetics of the pathogens. The results showed that CAP treatment effectively reduced L. monocytogenes and Salmonella levels. The Weibull + tail model showed better goodness of fit than the Weibull model. Protein-soiled coupons showed a protective effect to cold plasma inactivation achieving lower reductions compared to clean stainless-steel coupons for both L. monocytogenes and Salmonella. Longer distances from the plasma source decreased the decontamination efficiency of CAP; however, the difference in pathogen reduction was less pronounced at longer exposure times. This study demonstrates the capacity of a low-voltage piezoelectric CAP device to effectively reduce the levels of both foodborne pathogens on stainless-steel surfaces and the potential to adopt this technology by the food industry as a disinfection process of surfaces to reduce cross-contamination and thus increase safety.

The Influence of Cold Atmospheric Pressure Plasma-Treated Media on the Cell Viability, Motility, and Induction of Apoptosis in Human Non-Metastatic (MCF7) and Metastatic (MDA-MB-231) Breast Cancer Cell Lines.

Breast cancer remains the most common type of cancer, occurring in middle-aged women, and often leads to patients’ death. In this work, we applied a cold atmospheric pressure plasma (CAPP)-based reaction-discharge system, one that is unique in its class, for the production of CAPP-activated media (DMEM and Opti-MEM); it is intended for further uses in breast cancer treatment. To reach this aim, different volumes of DMEM or Opti-MEM were treated by CAPP. Prepared media were exposed to the CAPP treatment at seven different time intervals and examined in respect of their impact on cell viability and motility, and the induction of the apoptosis in human non-metastatic (MCF7) and metastatic (MDA-MB-231) breast cancer cell lines. As a control, the influence of CAPP-activated media on the viability and motility, and the type of the cell death of the non-cancerous human normal MCF10A cell line, was estimated. Additionally, qualitative and quantitative analyses of the reactive oxygen and nitrogen species (RONS), generated during the CAPP operation in contact with analyzed media, were performed. Based on the conducted research, it was found that 180 s (media activation time by CAPP) should be considered as the minimal toxic dose, which significantly decreases the cell viability and the migration of MDA-MB-231 cells, and also disturbs life processes of MCF7 cells. Finally, CAPP-activated media led to the apoptosis of analyzed cell lines, especially of the metastatic MDA-MB-231 cell line. Therefore, the application of the CAPP system may be potentially applied as a therapeutic strategy for the management of highly metastatic human breast cancer.

Plasma medicine and wound management: Evaluation of the antibacterial efficacy of a medically certified cold atmospheric argon plasma jet

Objectives: A major problem for wound healing is contamination with bacteria, often resulting in biofilm formation and wound infection, which, in turn, needs immediate intervention such as surgical debridement and through irrigation. A topical treatment with cold atmospheric pressure plasma (CAP) for wound disinfection may present an alternative and less painful approach.Methods: This study investigated the antibacterial effects of a cold atmospheric pressure argon plasma jet (kINPen® MED) as a CAP source, using the three-dimensional Staphylococcus aureus immunocompetent biofilm system hpBIOM in addition to a standard planktonic test. Furthermore, skin cell compatibility was evaluated using a keratinocyte (HaCat) model.Results: CAP treatment (0–240 s) followed by incubation (15, 120 min) within the CAP-treated media showed slight bactericidal efficacy under planktonic conditions but no effect on biofilms. However, indirect CAP treatment of keratinocytes performed under the same conditions resulted in a significant decrease in metabolic activity. Short CAP treatment and exposure time (30 s; 15 min) induced a slight increase in the metabolic activity; however, longer treatments and/or exposure times led to pronounced reductions up to 100%. These effects could partially be reversed by addition of catalase, indicating a dominant role of CAP-generated hydrogen peroxide.Conclusions: These results indicate that plasma treatment does not lead to the desired disinfection or significant reduction in the bacterial burden of Staphylococcus aureus in a wet milieu or in biofilms. Thus, treatment with CAP could not be recommended as a single anti-bacterial therapy for wounds but could be used to support standard treatments.

Enhanced In situ Activity of Peroxidases and Lignification of Root Tissues after Exposure to Non-Thermal Plasma Increases the Resistance of Pea Seedlings

Improving the germination of economically important crops and the condition of young plants is a major challenge currently facing agricultural practice. Pea (Pisum sativum L.) is one of the four most important cultivated legumes, along with groundnut (Arachis hypogaea L.), soybean (Glycine max L.) and beans (Phaseolus vulgaris L.). Due to the high protein content (23–33%), there is an interest in growing this crop as a source of protein for humans and animals. In this study, we focused on the effect of Cold Atmospheric Pressure Plasma (CAPP) on the decontamination and germination of pea seeds, on young seedling growth and production parameters, and on increasing their resistance and mechanical strength. We can state that germination increased by 10 to 25% after plasma treatment, and the most significant decontamination effect was detected when using non-thermal plasma generated in the ambient air (A-variants) and in the nitrogen atmosphere (N-variants). The increased in situ activity of peroxidases (POX) in the cell walls of A-variants and N-variants is also closely related to the increase in the mechanical strength of the cell walls and thus contributes to the higher resistance of these seedlings. This is also illustrated by the differences in lignin deposition among the different variants after CAPP treatment. To our knowledge, this is the first study concerning the influence of CAPP on the lignification of root tissues and on increasing the strength and resistance of plants.

Effects of cold atmospheric-pressure plasma on the rheological properties of gum Arabic

The main focus of current research was on the effect of cold atmospheric-pressure plasma (CAP) on the rheological properties of gum Arabic (GA). GA powder was treated by dielectric barrier discharge (DBD) plasma with ambient air at different times (20, 40, and 60 min). The rheological properties of both natural and treated-gum dispersions were specified. The results showed the CAP treatment time had a notable and non-linear effect on the rheological parameters of the treated gums. Compared with control, all treated-gum dispersions showed higher apparent viscosity within the applied shear rate range (0.01–400 s−1). The highest viscosity (50 s−1) belonged to the dispersion of the gum treated for 20 min. CAP treatment significantly (p < 0.05) increased the shear-thinning behavior of the treated-gum dispersions. Power-law was the best model for describing the flow behavior of natural GA and treated-gum dispersions. The obtained dynamic rheological parameters (G′ and tan δ) revealed that CAP treatment reinforced the elastic properties of treated-gum dispersions, and the shortest treatment time, 20 min, was more effective in this case. Overall, it was found that the CAP-treated gums by strengthening the elastic features of dispersions could be obtained for new applications in the production of foodstuffs especially beverages.

Cold atmospheric pressure plasma‐assisted removal of aflatoxin B1 from contaminated corn kernels

AbstractMycotoxins, the toxic secondary metabolites produced by filamentous fungi, are found in up to 80% of global food and feed crops. Here, we report on the complete removal of aflatoxin B1 (AFB1) from the artificially contaminated corn kernels with an indirect cold atmospheric pressure plasma (CAP) treatment generated with a surface barrier discharge system working in ambient air. Surface analysis of the corn kernels revealed the presence of minor changes in the treated samples, indicating that indirect CAP treatments induced slight oxidation of the corn kernel surface. This study not only proposes CAP as an effective food processing method for the decontamination of mycotoxins but also presents the first step towards acceptance of CAP technology as a safe food processing method.

Indirect Cold Atmospheric Pressure Plasma treatment on Melanoma and Fibroblast Cells

Cold atmosphere plasma has been shown as a promising technology for certain cancer treatments. In this paper, we report indirect plasma treatment using CAP discharged in cell culture medium and study the effect of identical plasma stimulated culture medium on melanoma cancer cells and fibroblast cells cultured in vitro. The results of MTT assay, migration assay, ROS detection, and alizarin red assay show that plasma-treated medium can have a strong negative effect on melanoma cancer cells compared with the control group. However, the plasma-treated medium has a less cytotoxic effect on fibroblast cells than that on melanoma cancer cells at the same treatment. This result is attributed to the production of reactive oxygen species in the plasma-treated medium to induce apoptosis and inhibit melanoma cell proliferation and further cell metastasis. According to the results, this study shows the potential of CAP plasma treatment for anti-cancer therapy.

Cold atmospheric‐pressure plasma treatment of turmeric powder: microbial load, essential oil profile, bioactivity and microstructure analyses

SummaryTurmeric powder treated by cold atmospheric‐pressure plasma (CAPP) at 25 kV for various times of 3, 5 and 7 min was examined for microbial load, essential oil profile, colour parameters, total phenolic content, total flavonoid content, antioxidant activity and microstructure. CAPP treatment caused a reduction of approximately 1.5 log CFU g−1 in aerobic viable cell count of turmeric powder, which was most pronounced during the first 3 min of the treatment. The inactivation kinetic was fitted to the Weibull model with R2 of 0.9913 and RMSE of 0.0641. Gas chromatography–mass spectrometry analysis of essential oils identified twelve different components for turmeric powder of which 1,8‐Cineole, α‐Terpinolene and trans‐Caryophyllene were lost and ar‐Turmerone and α‐Zingiberene experienced considerable increases after plasma treatment. The double‐edged effect of plasma treatment was also observed on bioactivity. Scanning electron microscopy showed formation of super‐agglomerates in plasma‐treated samples due probably to coalescence of the granules with plasma‐damaged walls.

Cold atmospheric pressure plasma treatment for adhesion improvement on polypropylene surfaces

Cold atmospheric pressure plasma from a plasma jet was used to improve the adhesion properties of polypropylene (PP). Differences in adhesion were at first observed for either air or N2 as process gas, tested on a PP-acrylic pressure sensitive adhesive (PSA) model system. For a deeper understanding changes in the surface chemistry and topography on PP after plasma jet treatment, using several different O2/N2 mixtures, were investigated in a comprehensive surface analytical study. Independent of the gas composition a majority of plasma induced polar groups exist as water soluble low molecular weight oxidized material (LMWOM), located within the first few nanometers. Consequently, the observed changes in the surface chemistry for various process gas compositions are mainly attributed to differences in the formed LMWOM. However, these chemical changes indicated also differences in the interaction mechanism of plasma reactive species with the polymer surface and therefore, in the resulting plasma-polymer etching process. Hence, significant changes in the topography have been observed for different process gas compositions, which could be reliably correlated with the obtained adhesion results.

Cold plasma decontamination of stainless steel food processing surfaces assessed using an industrial disinfection protocol

Cold atmospheric pressure plasma (CAP) stands out among new decontamination technologies, as it offers rapid antimicrobial action against a broad spectrum of foodborne pathogens, while minimally affecting the exposed target. Furthermore, it is low-cost, environmentally friendly and requires no consumables, allowing for scale-up and adaptation to meet industrial needs. This study evaluated an indirect CAP device against two common foodborne pathogens on stainless steel surfaces. The EN 13697:2015 protocol for chemical disinfectants was adopted, which simulates realistic conditions typically found in a food-processing facility. The impact of distance from the CAP source, treatment time and protocol parameters were investigated.It was demonstrated that distance from the CAP source was the most important factor. The system achieved a >3.55 logCFU/mL and 2.06 logCFU/mL reduction of Listeria monocytogenes and Salmonella typhimurium, respectively at 5 mm distance within 3 min. It was observed that the CAP exposure had a negligible effect on the stainless steel surface morphology. The results demonstrate that CAP is an effective means of reducing microbial loading in such environments.

Influence of Cold Atmospheric Pressure Plasma on Pea Seeds: DNA Damage of Seedlings and Optical Diagnostics of Plasma

Cold atmospheric pressure plasma treatment is currently being explored as an alternative way to improve the germination and growing parameters of plant seeds. However, it is important to pay attention to the effect of plasma treatment on DNA damage of the seeds as well as detailed characteristics of plasma composition and parameters. The aim of this work was to study the DNA damage of plasma-treated pea seeds (Pisum sativum L.) and plasma parameters such as the chemical composition of plasma gaseous compounds and plasma radiation. Seeds were treated with plasma using the diffuse coplanar surface barrier discharge generated in different working gases (ambient air, nitrogen, oxygen and different mixtures of oxygen and nitrogen) at atmospheric pressure and at 60 s, 180 s and 300 s exposure times. DNA damage was studied using the single cell-gel electrophoresis called the comet assay and the plasma parameters were investigated by Fourier transform infrared spectroscopy and optical emission spectroscopy. Experiments in different ratios of oxygen and nitrogen were realized in order to understand the reaction mechanism between the ambient air plasma and the treated seeds. Based on our results, ambient air plasma appears to be the most advantageous for the plasma treatment due to no significant DNA damage because of the proper combination of plasma composition in combination with water vapor present in ambient air.

Application of cold atmospheric pressure plasmas for high-throughput production of safe-to-consume beetroot juice with improved nutritional quality

A one-step, highly-efficiency, and low-cost cold atmospheric pressure plasma (CAPP)-based method for obtaining safe-to-consume beetroot juice (BRJ) with enhanced nutritional quality is presented. Three reaction-discharge systems with different CAPPs were studied to check how the composition and physicochemical properties changed during CAPP treatment of BRJ. To identify reactive species occur in gas phase of applied CAPP for BRJ treatment, optical emission spectrometry was used. Finally, the cytotoxicity of so-obtained BRJ to human epithelial colorectal adenocarcinoma (Caco-2) and human non-malignant intestine microvascular endothelial cells (HIMEC) was assessed. Based on the performed analyses it was found that controlled CAPP treatment of BRJ changes the fraction pattern of elements in addition to increase the content of phenolic compound presents in BRJ. Furthermore, the defined CAPP treatment of BRJ inhibits proliferation of Caco-2 cell lines, exhibiting non-cytotoxic effect for HIMEC non-malignant endothelial cells. As a result, safe-to-consume BRJ of improved nutritional quality was produced.