Effect of the pH on the Antibacterial Potential and Cytotoxicity of Different Plasma-Activated Liquids

Biocompatible plasma-treated liquids: A sustainable approach for decontaminating gastrointestinal-infection causing pathogens

Nosocomial infections are a serious threat and difficult to cure due to rising antibiotic resistance in pathogens and biofilms. Direct exposure to cold atmospheric plasma (CAP) has been widely employed in numerous biological research endeavors. Nonetheless, plasma-treated liquids (PTLs) formulated with physiological solutions may offer additional benefits such as enhanced portability, and biocompatibility. Additionally, CAP-infused long-lived reactive oxygen and nitrogen species (RONS) such as nitrite (NO2-), nitrate (NO3-), and hydrogen peroxide (H2O2) can synergistically induce their antibacterial activity. Herein, we investigated those argon-plasma jet-treated liquids, including Ringer's lactate (RL), phosphate-buffered saline (PBS), and physiological saline, have significant antibacterial activity against nosocomial/gastrointestinal-causing pathogens, which might be due to ROS-mediated lipid peroxidation. Combining the conventional culture-based method with propidium iodide monoazide quantitative PCR (PMAxx™-qPCR) indicated that PTLs induce a minimal viable but non-culturable (VBNC) state and moderately affect culturable counts. Specifically, the PTL exposure resulted in pathogenicity dysfunction via controlling T3SS-related effector genes of S. enterica. Overall, this study provides insights into the effectiveness of PTLs for inducing ROS-mediated damage, controlling the virulence of diarrheagenic bacteria, and modulating homeostatic genes.

Ascorbic acid as a modulator of inflammatory response against Candida albicans

Aim: To evaluate the behavior of oral keratinocytes in the presence of Vitamin C (Vit C) and its anti-inflammatory potential. Materials & methods: Oral keratinocytes were initially exposed to 0.1-2.5 mM of Vit C and the metabolic activity and cell migration were evaluated using MTS assay and Ibidi culture inserts, respectively. After, the cells were challenged with Candida albicans and inflammatory markers were analyzed by qPCR. Results: The treatment was not cytotoxic, and the highest concentrations increased the metabolic activity at 24 h. Vit C delayed the cell migration at 48 and 72 h. Interestingly, it downregulated the genes IL-8 and IL-1β. Conclusion: Vit C could be an interesting adjuvant to anti-fungal treatment due to its anti-inflammatory potential.

Novel Energetic Co-Reactant for Thermal Oxide Atomic Layer Deposition: The Impact of Plasma-Activated Water on Al2O3 Film Growth

In the presented study, a novel approach for thermal atomic layer deposition (ALD) of Al2O3 thin films using plasma-activated water (PAW) as a co-reactant, replacing traditionally employed deionized (DI) water, is introduced. Utilizing ex situ PAW achieves up to a 16.4% increase in the growth per cycle (GPC) of Al2O3 films, consistent with results from plasma-enhanced atomic layer deposition (PEALD). Time-resolved mass spectrometry (TRMS) revealed disparities in CH4 partial pressures between TMA reactions with DI water and PAW, with PAW demonstrating enhanced reactivity. Reactive oxygen species (ROS), namely H2O2 and O3, are posited to activate Si(100) substrate sites, thereby improving GPC and film quality. Specifically, Al2O3 films grown with PAW pH = 3.1 displayed optimal stoichiometry, reduced carbon content, and an expanded bandgap. This study thus establishes "PAW-ALD" as a descriptor for this ALD variation and highlights the significance of comprehensive assessments of PAW in ALD processes.

Analyses of the Chemical Composition of Plasma-Activated Water and Its Potential Applications for Vaginal Health

This study aimed to elucidate the unique chemical compositions of plasma-activated water (PAW) and the potential antibacterial efficacy of PAW as a novel vaginal cleanser. We analyzed the ion compositions (four anions: F-, Cl-, NO3-, SO42-; five cations: Na+, NH4+, K+, Mg2+, Ca2+) of several formulations of PAW generated at different electrical powers (12 and 24 V) at various treatment time points (1, 10, and 20 min), and stay durations (immediate, 30, and 60 min). As treatment duration increased, hypochlorous acid (HOCl), Ca2+, and Mg2+ concentrations increased and Cl- concentration decreased. Higher electrical power and longer treatment duration resulted in increased HOCl levels, which acts to prevent the growth of general microorganisms. Notably, PAW had no antibacterial effects against the probiotic, Lactobacillus reuteri, which produces lactic acid and is important for vaginal health. These findings indicate that PAW contains HOCl and some cations (Ca2+ and Mg2+), which should help protect against pathogens of the vaginal mucosa and have a cleansing effect within the vaginal environment while not harming beneficial bacteria.

Bactericidal efficacy difference between air and nitrogen cold atmospheric plasma on Bacillus cereus: Inactivation mechanism of Gram-positive bacteria at the cellular and molecular level

As an emerging food processing technology, cold atmospheric plasma (CAP) has attracted great attention in the field of microbial inactivation. Although CAP has been proven to effectively inactivate a variety of foodborne pathogens, there is less research on the inactivation of Bacillus cereus, and the exact inactivation mechanism is still unclear. Elucidating the inactivation mechanism will help to develop and optimize this sterilization method, with the prospective application in industrialized food production. This study aims to explore the bactericidal efficacy difference between air and nitrogen CAP on B. cereus, a typical Gram-positive bacterium, and reveals the inactivation mechanism of CAP at the cellular and molecular level, by observing the change of the cell membrane, cell morphological damage, intracellular antioxidant enzyme activity and cellular biomacromolecules changes. The results showed that both air CAP and nitrogen CAP could effectively inactivate B. cereus, which was due to the reactive oxygen and nitrogen species (RONS) generated by the plasma causing bacterial death. The damage pathways of CAP on Gram-positive bacteria could be explained by disrupting the bacterial cell membrane and cell morphology, disturbing the intracellular redox homeostasis, and destroying biomacromolecules in the cells. The differences in active species generated by the plasma were the main reason for the different bactericidal efficiencies of air CAP and nitrogen CAP, where air CAP producing RONS with stronger oxidative capacity in a shorter time. This study indicates that air CAP is an effective, inexpensive and green technology for B. cereus inactivation, providing a basis for industrial application in food processing.

A review on plasma-activated water and its application in the meat industry

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.

Advancements in Plasma Agriculture: A Review of Recent Studies

This review is devoted to a topic of high interest in recent times-the use of plasma technologies in agriculture. The increased attention to these studies is primarily due to the demand for the intensification of food production and, at the same time, the request to reduce the use of pesticides. We analyzed publications, focusing on research conducted in the last 3 years, to identify the main achievements of plasma agrotechnologies and key obstacles to their widespread implementation in practice. We considered the main types of plasma sources used in this area, their advantages and limitations, which determine the areas of application. We also considered the use of plasma-activated liquids and the efficiency of their production by various types of plasma sources.

Neutral - Eradication of As (III) and Congo red (CR) with green iron oxide (GIO) loaded chitosan(C) - (C - GIO) beads by a non - Thermal plasma jet via potential study

In this potential - study, the non - thermal atmospheric pressure plasma is utilized for the neutral - eradication of water contaminants. In the air ambient region, plasma induced reactive species, like as OH^•, O (O₂^-), H₂O₂ (OH^•+OH^•) & NO_x are performed for the oxidative and reductive transformation of As^III (H₃AsO₃) to As^V (H₂As O₄^-) & Fe₃O₄ (Fe³⁺) (C-GIO) to Fe₂O₃ (Fe²⁺). Whereas, the H₂O₂ & NO_x are quantified maximum (max.) in water, which is 144.24 & 111.82 μM, respectively. In the absence of plasma and plasma with C-GIO, the As^III was more eradicated, which is 64.01 and 100.00%. While, the C - GIO (catalyst) synergistic enhancement was performed and proved by the neutral - degradation of CR. Also, the As^V adsorbed on C-GIO adsorption capacity q_max and redox-adsorption yield were evaluated, which are 1.36 mg/g and 20.80 g/kWh, respectively. In this research, the waste material (GIO) was recycled, modified, and utilized for the neutral - eradication of water contaminates, which are organic (CR) and inorganic (As^III) toxicants by the controlling of H and OH^• under the interaction of plasma with catalyst (C-GIO). However, in this research, plasma can't adopt the acidic, which is controlled by the C-GIO via RONS. Moreover, in this eradicative study, various water pH alignments were performed, from neutral to acidic & neutral & base for toxicants removal. Furthermore, according to WHO norms, the arsenic level was reduced to 0.01 mg/l for environmental safety. The kinetic and isotherm studies were followed by the mono and multi-layer adsorption was performed on the surface of C - GIO beads, which is estimated by the fitting of rate limiting constant R² ≈ 1. Furthermore, the C-GIO was examined several characterizations alignments, such as crystal, surface, functional, elemental composition, retention time, mass spectrum, and elemental oriented properties. Overall, the suggested hybrid system is an eco-friendly pathway for the natural - eradication of contaminants, such as organic and inorganic compounds via waste material (GIO) recycling, modification, oxidation, reduction, adsorption, degradation, and neutralization phenomenon.

Effect of Gliding Arc Plasma Jet on the Mycobiota and Deoxynivalenol Levels in Naturally Contaminated Barley Grains

Fusarium graminearum and Fusarium meridionale are primary contaminants of barley, capable of producing several mycotoxins, mainly type B trichothecenes and zearalenone. Cold plasma decontamination has been gaining prominence, seeking to control the fungal and mycotoxin contamination of food and feed and to improve product quality. To reach this objective, the present study was divided into two parts. In the first part, F. meridionale and F. graminearum strains were exposed to gliding arc plasma jet (GAPJ). Cell viability tests showed the inactivation of F. meridionale after 15-min treatment, whereas F. graminearum showed to be resistant. In the second part, barley grains were treated by GAPJ for 10, 20, and 30 min, demonstrating a reduction of about 2 log CFU/g of the barley's mycobiota, composed of yeasts, strains belonging to the F. graminearum species complex, Alternaria, and Aspergillus. A decrease in DON levels (up to 89%) was observed after exposure for 20 min. However, an increase in the toxin Deoxynivalenol-3-glucoside (D3G) was observed in barley grains, indicating a conversion of DON to D3G.

Effect of Plasma On-Time with a Fixed Duty Ratio on Reactive Species in Plasma-Treated Medium and Its Significance in Biological Applications

Optimizing the therapeutic range of nonthermal atmospheric pressure plasma (NTAPP) for biomedical applications is an active research topic. For the first time, we examined the effect of plasma on-times in this study while keeping the duty ratio and treatment time fixed. We have evaluated the electrical, optical, and soft jet properties for two different duty ratios of 10% and 36%, using the plasma on-times of 25, 50, 75, and 100 ms. Furthermore, the influence of plasma on-time on reactive oxygen and nitrogen species (ROS/RNS) levels in plasma treated medium (PTM) was also investigated. Following treatment, the characteristics of (DMEM media) and PTM (pH, EC, and ORP) were also examined. While EC and ORP rose by raising plasma on-time, pH remained unchanged. Finally, the PTM was used to observe the cell viability and ATP levels in U87-MG brain cancer cells. We found it interesting that, by increasing the plasma on-time, the levels of ROS/RNS dramatically increased in PTM and significantly affected the viability and ATP levels of the U87-MG cell line. The results of this study provide a significant indication of advancement by introducing the optimization of plasma on-time to increase the efficacy of the soft plasma jet for biomedical applications.

Simultaneous Treatment of Both Sides of the Polymer with a Conical-Shaped Atmospheric Pressure Plasma Jet

A conical-shaped atmospheric pressure plasma jet (CS-APPJ) was developed to overcome a standard limitation of APPJs, which is their small treatment area. The CS-APPJs increase the treatment area but use the same gas flow. In the present work, polypropylene samples were treated by CS-APPJ and characterized by scanning electron microscope (SEM), the contact angle, Fourier-transformed infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). It was observed that the treatment co-occurs on the face directly in contact with the plasma and on the opposite face (OF) of the samples, i.e., no contact. However, the treatment changed the chemical composition on each side; the OF is rougher than the direct contact face (DCF), probably due to the oxygen groups in excess at the DCF and nitrogen in quantity at the OF. Although simultaneous treatment of both sides of the sample occurs for most atmospheric plasma treatments, this phenomenon is not explored in the literature.