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(a) Analysis of oxidative related gene expressions, (b) cell morphology and (c) DNA damage after 3 hr incubation with PTW generated by N 2 , N 2 + H 2 O vapor and N 2 + 0.5% HNO 3 vapor.
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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 plas...
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Surface modification of fiber fabric sometimes needs a large volume of cold plasma to improve its efficiency. This experimental study is based on the treatment of polyamide 66 (PA66) fabrics using large contact-area glow-like plasma, which are produced in the atmospheric air without any dielectric barriers. The atomic force microscopy (AFM) and X-r...
Cold atmospheric plasmas (CAPs) are being used in applications related to dentistry. Potential benefits include tooth whitening/bleaching, the sterilization of dental cavities, and root canal disinfection. Generated reactive species, such as hydroxyl (OH) radicals, play a critical role in the effectiveness of CAPs in dentistry. In the present work,...
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... Soft jet plasmas are created by applying electrical energy to ambient air, creating a high-energy environment that facilitates unique reactions forming various ROS and RNS 43,44 . The formation of nitrogen oxides (NO x ), including NO (nitric oxide), NO 2 (nitrogen dioxide), and N 2 O (nitrous oxide), in a soft jet plasma involves complex chemical reactions 13 . The main reactions leading to NO formation involve the dissociation of nitrogen molecules (N 2 ) and their combination with oxygen molecules (O 2 ) driven by high-energy electrons (e − ) in the plasma (Eq. ...
The aim of this study was to evaluate the antimicrobial efficacy of an air gas soft jet CAP for its potential use in removing oral biofilms, given that plasma-based technologies have emerged as promising methods in periodontology. Two types of biofilms were developed, one by Streptococcus mutans UA 159 bacterial strain and the other by a complex mixture of saliva microorganisms isolated from a patient with periodontitis. This latter biofilm was characterized via Next Generation Sequencing to determine the main bacterial phyla. The CAP source was applied at a distance of 6 mm for different time points. A statistically significant reduction of both CFU count and XTT was already detected after 60 s of CAP treatment. CLSM analysis supported CAP effectiveness in killing the microorganisms inside the biofilm and in reducing the thickness of the biofilm matrix. Cytotoxicity tests demonstrated the possible use of CAP without important side effects towards human gingival fibroblasts cell line. The current study showed that CAP treatment was able to significantly reduce preformed biofilms developed by both S. mutans and microorganisms isolated by a saliva sample. Further studies should be conducted on biofilms developed by additional saliva donors to support the potential of this innovative strategy to counteract oral pathogens responsible for periodontal diseases.
... Plasma-liquid interactions enable the generation of highly reactive species in solution that have been shown to enable various applications, 1 including wound healing, 2 bacterial inactivation, 3 nanoparticle synthesis, 4 and wastewater treatment. 5,6 The short lifetime of many plasma-produced reactive species limits their penetration into the solution to depths on the order of 10 s of nanometers to micrometers. ...
... The authors of the work of Lindsay et al. 21 have shown that convective mixing in the liquid phase increases the concentration of plasma-produced HNO 3 and NO. The authors of the work of Delgado et al. 22 have modeled controlled convective transport, suggesting that liquid flow velocities of the order of 100 m/s would be needed to minimize the transport limitations and avoid recombination of short-lived species before reacting with solutes in the solution. ...
... Therefore, in thin films, the high pH can be seen for a large portion of the film whereas this is not the case in thick films. pH measurements after plasma treatment for HNO 3 and NaNO 3 show a delay in reduction explainable by a reduction in HO − 2 formation from H 2 O 2 at lower pH values 43 (supplementary material, Sec. 4). Despite the overall negligible pH rise for the case when HNO 3 was added to the solution, likely a thin layer with slightly increased pH will still be enabled by the plasma compared to the reference case. ...
Many applications involving plasma–liquid interactions depend on the reactive processes occurring at the plasma–liquid interface. We report on a falling liquid film plasma reactor allowing for in situ optical absorption measurements of the time-dependence of the ferricyanide/ferrocyanide redox reactivity, complemented with ex situ measurement of the decomposition of formate. We found excellent agreement between the measured decomposition percentages and the diffusion-limited decomposition of formate by interfacial plasma-enabled reactions, except at high pH in thin liquid films, indicating the involvement of previously unexplored plasma-induced liquid phase chemistry enabled by long-lived reactive species. We also determined that high pH facilitates a reduction-favoring environment in ferricyanide/ferrocyanide redox solutions. In situ conversion measurements of a 1:1 ferricyanide/ferrocyanide redox mixture exceed the measured ex situ conversion and show that conversion of a 1:1 ferricyanide/ferrocyanide mixture is strongly dependent on film thickness. We identified three dominant processes: reduction faster than ms time scales for film thicknesses >100 µm, •OH-driven oxidation on time scales of <10 ms, and reduction on 15 ms time scales for film thickness <100 µm. We attribute the slow reduction and larger formate decomposition at high pH to HO2− formed from plasma-produced H2O2 enabled by the high pH at the plasma–liquid interface as confirmed experimentally and by computed reaction rates of HO2− with ferricyanide. Overall, this work demonstrates the utility of liquid film reactors in enabling the discovery of new plasma-interfacial chemistry and the utility of atmospheric plasmas for electrodeless electrochemistry.
... Previous studies [27][28][29] have shown that plasma treatment is highly effective in the destruction of bacteria, pesticides [30], pharmaceuticals [31,32], organic dyes [33], and PFAS [34,35]. ...
The present study focuses on the characterization of a hyperbolic vortex plasma reactor through the comparison of various plasma-atmospheric regimes for the production efficiency of reactive nitrogen (RNS) and reactive oxygen (ROS) species. The research also explores effectiveness in the removal of micropollutants, including pharmaceuticals and per- and polyfluoroalkyl substances (PFAS). The technology includes several degradation mechanisms, such as advanced oxidation, ultraviolet photolysis, ozonation, electrolysis, and shockwave water purification, without the need for additional chemicals. Our results indicate that the plasma of bipolar or "flashover" mode is notably more effective and efficient than both positive or negative polarity. Through the testing of various energy levels, it has been demonstrated that higher energy plasma yields lower efficiency but necessitates shorter treatment times compared to lower energy treatment. When plasma is produced under ambient atmosphere, water chemical properties change significantly in comparison to treatment under argon or nitrogen due to the presence of both oxygen and nitrogen molecules. In a nitrogen atmosphere, the predominant formation is of RNS due to the chemical reactivity of nitrogen exited states, whereas under argon atmosphere, predominantly ROS are generated. Notable advantages of this technology are its scalability and its low energy requirements. The scalability of the technology involves increasing the size of the reactor, the power and electrode count.
... Many studies have demonstrated the high efficacy of cold plasma against a wide range of pathogenic bacteria (Min et al., 2016;Modic et al., 2017;Timmons et al., 2018;Niveditha et al., 2021). Exposing liquid solutions to plasma leads to the production of many free radicals, such as the hydroxyl (•OH⋅) radical oxygen (O), ozone (O 3 ), hydrogen peroxide (H 2 O 2 ) and nitric oxide (NO) radicals that play a significant role in the enhanced antimicrobial effect , (Shaw et al., 2018). ...
... Our results demonstrate that plasma and PAW generated by argon gas at different flow rates and time exposure can result in differing levels of fungal inactivation. The efficiency of antimicrobial activity depends on the chemical species generated by plasma which rely on gas feeding, flow rate, treatment time and environmental factors and microbial species 25,29,30 . In these studies, we demonstrate that the mycelial growth of A. apis can be totally inhibited by argon plasma. ...
... Thus, these reactive oxygen species generated by argon plasma could play important roles in fungal inactivation. Several studies have reported that ROS and RNS produced by plasma play crucial roles in microbial inactivation [23][24][25] . The reactive species can cause oxidative stress, lipid peroxidation, enzyme inactivation, cell leakage and DNA damage [32][33][34] . ...
Ascosphaera apis is a worldwide pathogenic fungi of honeybees that can cause a decline in bee populations. In this study, we investigated the antifungal activity of non-thermal plasma on fungal growth. Spore inactivation after exposure to gas plasma by liquid phase and plasma activated water (PAW) and pathogenicity of A. apis in vivo were also examined. The results demonstrated that the mycelial growth of fungi was completely inhibited after argon plasma treatment. Both gas plasma and PAW exposures resulted in a significant decrease of A. apis spore numbers, maximum reduction of 1.71 and 3.18-fold, respectively. Germinated fungal spores on potato dextrose agar were also reduced after plasma treatment. SEM analysis revealed a disruption in the morphological structure of the fungal spores. The pathogenicity of A. apis on honeybee larvae was decreased after spores treated by gas plasma and PAW with a disease inhibition of 63.61 ± 7.28% and 58.27 ± 5.87%, respectively after 7 days of cultivation. Chalkbrood in honey bees have limited control options and our findings are encouraging. Here, we demonstrate a possible alternative control method using non-thermal plasma for chalkbrood disease in honeybees.
... Direct CAP application has some limitations due to the narrow possibility of delivering RONS to internal target tissues. On the other hand, the indirect approach leads to the production of RONS more exibly by the activation of different kinds of liquids with CAP and their administration as a treatment, regardless the target's anatomic location [5,11,12,15,16]. In this process, the CAP-derived RONS are delivered from the plasma gas phase into the liquid phase, yet leaving a delicate mixture of long-lived RONS, able to further recombine or react again to form intracellular short-lived species [12,14]. ...
Objective: Cold atmospheric plasma (CAP) is a novel therapeutic approach for cancer treatment. It can be used to treat liquids - plasma-activated media (PAM) - which are then transferred to the target as an exogenous source of reactive oxygen and nitrogen species (RONS). The present study aimed at chemically characterizing different PAM and assessing their in vitro selectivity against head and neck cancer cell lines (HNC).
Materials and methods: PAM were obtained by exposing 2 and 5 mL of medium to CAP for 5, 10 and 20 minutes at a 6 mm working distance. Anions kinetics was evaluated by ion chromatography. In addition, inhibition of cell proliferation by MTS assay, apoptosis occurrence and cell cycle modifications by flow cytometry were assessed on primary human gingival fibroblasts (hGF) and the HNC cell lines HSC2, HSC4 and A253.
Results: All the 2 mL conditions showed a significant reduction in cell proliferation whereas for the 5 mL the effect was milder, but the time-dependence was more evident. In addition, hGF were unaffected by the 5 mL PAM, indicating a selectivity for cancer cells.
Conclusions: The media chemical composition modified by CAP exposure influenced cell proliferation by modulating cell cycle and inducing apoptosis in cancer cells, without affecting normal cells.
Clinical Relevance: The present investigation represents a starting point to favour the clinical translation of CAP as a precision medicine tool by proposing an innovative method, namely ion chromatography, to standardize the quantification of plasma-derived RONS and proving its selectivity in inactivating tumor cells over non-malignant cells. These strategies could be applied to identify the optimal parameter configuration to achieve the desired treatment/therapeutic outcome and to aid the definition of clinical protocols.
... NO possesses potent antimicrobial properties, allowing it to target a broad spectrum of pathogenic bacteria, including S. enterica, S. flexneri, and V. parahaemolyticus. The mechanism behind NO antimicrobial action is attributed to the presence of reactive nitrogen species (RNS), such as peroxynitrite (ONOO− ) and NO radical (NO•), which disrupt vital cellular components and critical biological pathways, leading to growth inhibition and eventual bacterial death (Borkar et al., 2023;Fang and Vázquez-Torres, 2019;Machala et al., 2019;Shaw et al., 2018;Zhao and Drlica, 2014). In recent studies, the application of plasma-generated water has emerged as a promising treatment to inhibit the survival and virulence of bacteria (Mai-Prochnow et al., 2021;Wang et al., 2023). ...
... Consequently, disinfection through PG-NOW is a safe method to prevent VBNC formation. As reported earlier, there is growing evidence that RNS in PG-NOW is valuable for bacterial inactivation because it doesn't induce resistant or VBNC bacteria (Shaw et al., 2018) by directly inhibiting their growth. For the successful establishment of infection, pathogenic bacteria require adhesion to host cells, which occurs via the interaction of several bacterial surface proteins (Martino, 2018). ...
S. enterica, S. flexneri, and V. parahaemolyticus bacteria are globally recognized to cause severe diarrheal diseases, consisting of Type III Secretion System (T3SS) effectors that help in bacterial infection and virulence in host cells. This study investigates the properties of multi-electrode cylindrical DBD plasma-generated nitric oxide water (MCDBD-PG-NOW) treatment on the survival and virulence of S. enterica, S. flexneri, and V. parahaemolyticus bacteria. The Colony Forming Unit (CFU) assay, live/dead cell staining, lipid peroxidation assay, and bacteria morphological analysis showed substantial growth inhibition of bacteria. Moreover, to confirm the interaction of reactive nitrogen species (RNS) with bacterial membrane biotin switch assay, DAF-FM, and FTIR analysis were carried out, which established the formation of S-nitrosothiols in the cell membrane, intracellular accumulation of RNS, and changes in the cell composition post-PG-NOW treatment. Furthermore, the conventional culture-based method and a quantitative PCR using propidium monoazide showed minimal VBNC induction under similar condition. The efficiency of bacteria to adhere to mammalian colon cells was significantly reduced. In addition, the infection rate was also controlled by disrupting the virulent genes, leading to the collapse of the infection mechanism. This study provides insights into whether RNS generated from PG-NOW might be beneficial for preventing diarrheal infections.
... Recently, CAP has emerged as a new therapy that can deliver reactive oxygen nitrogen species (RONS) for biomedical applications [13][14][15][16][17][18][19][20] . CAP is a multi-component, chemically active, and highly reactive ionized gas that is generated at room temperature under atmospheric conditions, usually from noble gases (i.e., helium or argon), and ows into ambient air or is directly created in air. ...
... CAP is a multi-component, chemically active, and highly reactive ionized gas that is generated at room temperature under atmospheric conditions, usually from noble gases (i.e., helium or argon), and ows into ambient air or is directly created in air. The species created by CAP are mainly reactive oxygen nitrogen species (RNS), such as NO• and nitrogen dioxide (NO 2 ), as well as reactive oxygen species (ROS), such as ozone (O 3 CAP has shown to induce a variety of biological effects, such as blood coagulation 23 , tissue regeneration 24,25 , sterilization 13,23,26 , wound healing 23,27,28 , cancer cell death [14][15][16][17]21,23,26,29,30 , activation of immune cells 31,32 , and virus inactivation 33,34 . The type and concentration of CAP-generated species delivered to cells depend on the CAP operating conditions, controlled by the design of the source, including the con guration of the electrodes. ...
... As shown inSupplementary Fig. S3, the control cells exhibited typical thin and elongated morphology, while hGF cells stimulated with CAP, in particular at the longer exposure times (120s and 180s), showed morphological modi cations with loss of their elongated aspect and a reduction in cell number.DiscussionSoft jet plasmas are created by applying electrical energy to ambient air, creating a high-energy environment that facilitates unique reactions forming various RONS41,42 . The formation of nitrogen oxides (NO x ), including NO (nitric oxide), NO 2 (nitrogen dioxide), and N 2 O (nitrous oxide), in a soft jet plasma involves complex chemical reactions13 . The main reactions leading to NO formation involve produced by combining NO and NO 2 through a condensation reaction (Eqn. ...
The aim of this study was to evaluate the antimicrobial efficacy of an air gas soft jet CAP for its potential use in removing oral biofilms, given that plasma-based technologies have emerged as promising methods in periodontology. Two types of biofilms were developed, one by Streptococcus mutans UA 159 bacterial strain and the other by a complex mixture of saliva microorganisms isolated from a patient with periodontitis. This latter biofilm was characterized via Next Generation Sequencing to determine the main bacterial phyla. The CAP source was applied at a distance of 6mm for different time points. A statistically significant reduction of both CFU count and XTT was detected after 60s of CAP treatment, while the treatment for 120s resulted in both biofilms eradication. CLSM analysis supported CAP effectiveness in killing the microorganisms inside the biofilm and in reducing the thickness of the biofilm matrix. Cytotoxicity tests demonstrated the possible use of CAP without important side effects towards human gingival fibroblasts cell line. The current study showed that CAP treatment was able to eradicate preformed biofilms developed by both S. mutans and the complex mixture of saliva microorganisms, representing a potential innovative strategy to counteract oral pathogens responsible for periodontal diseases.
... Recently, there has been a growing interest in cold atmosphere plasma (CAP) sources due to emerging plasma applications such as cancer treatment [1][2][3][4], skin treatment [5][6][7][8], sterilization [9][10][11][12], wound healing [13,14], and plasma-activated medium [15][16][17][18]. In the last two decades, several CAPs have been introduced for these applications in research and commercial products, e.g., plasma pencil and kINPen [19][20][21]. ...
... The minimum plasma jet length was observed to be 7 mm at [flow rate (L/min), applied voltage (kV)] = [1,8], and the maximum jet length was acquired to be 17 mm at [flow rate (L/min), applied voltage(kV)] = [3,10]. Although increased applied voltage contributes to the enhancement of jet length, a part of the input energy is spent on heating the discharge gas as well as the reactor, resulting in variation of jet temperature with respect to input parameters. ...
A multiple-capillary Ar plasma jet was successfully generated by an advanced dielectric barrier discharge reactor. The reactor consisted of four quartz capillaries arranged separately and covered by two ring-shaped electrodes, which were isolated by a liquid dielectric. The advantages of the reactor included less Ar consumption (ranging from 1 to 3 L/min to obtain a total cross-sectional area of four individual plasma flow components of 3.14 mm2 at the capillary orifices) and low gas temperatures (not exceeding 40 °C). The obtained temperature is suitable for implementing various biomedical applications such as wound healing, dental treatment, and cancer therapy. Furthermore, the plasma jet spread when it interreacted with dielectric materials or skin, resulting in an enlarged effective plasma treatment area of approximately 8 mm2. Analysis of optical emission spectra of the plasma jet indicated the existence of several reactive species, suggesting that the plasma device holds potential for biomedical applications and material surface treatments.
... They found that the optimal inactivation, at 0.45 and 2.45 log 10 reduction CFU.mL −1 against E. coli and S. aureus, respectively, was achieved with 99% Ar (and 1% O 2 ) at 4 L.min −1 for 11.5 min of treatment. Shaw et al. (2018) revealed that the gas mixture of nitrogen and 0.5 wt% of vapor nitric acid led to the highest antimicrobial inactivation of PAW against E. coli compared to other gas mixtures, such as nitrogen and nitrogen with water vapor. In addition, Ali et al. (2021) showed that in comparison with a gas mixture of argon and oxygen, higher reductions of chlorothalonil and thiram pesticide residues on tomato were achieved by PAW when the air was introduced during plasma discharge, which is associated with the enhanced RONS production in PAW when using air as the working gas. ...
Meat is a nutritious food with a short shelf life, making it challenging to ensure safety, quality, and nutritional value. Foodborne pathogens and oxidation are the main concerns that lead to health risks and economic losses. Conventional approaches like hot water, steam pasteurization, and chemical washes for meat decontamination improve safety but cause nutritional and quality issues. Plasma‐activated water (PAW) is a potential alternative to thermal treatment that can reduce oxidation and microbial growth, an essential factor in ensuring safety, quality, and nutritional value. This review explores the different types of PAW and their physiochemical properties. It also outlines the reaction pathways involved in the generation of short‐lived and long‐lived reactive nitrogen and oxygen species (RONS) in PAW, which contribute to its antimicrobial abilities. The review also highlights current studies on PAW inactivation against various planktonic bacteria, as well as critical processing parameters that can improve PAW inactivation efficacy. Promising applications of PAW for meat curing, thawing, and decontamination are discussed, with emphasis on the need to understand how RONS in PAW affect meat quality. Recent reports on combining PAW with ultrasound, mild heating, and non‐thermal plasma to improve inactivation efficacy are also presented. Finally, the need to develop energy‐efficient systems for the production and scalability of PAW is discussed for its use as a potential meat disinfectant without compromising meat quality.
