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Plasma-activated hydrogels have promising application prospects in the field of transdermal penetration therapy, such as subcutaneous tumours, due to their long-lasting, slow-release properties and ability to be easily applied to skin. In this study, surface air plasma was used to prepare plasma-activated Aristoflex AVC hydrogel (PAH) and plasma-activated water (PAW) by irradiation. The characteristics of PAH and PAW were further studied in terms of reactive oxygen species (ROS) storage, transdermal permeation, and in vitro anticancer effects in an artificial skin model. The experimental results showed that PAH had a prolonged storage time of ROS and more transdermal permeation of ROS through artificial skin in Franz diffusion cell after 30 h compared to PAW, which means PAH could be superior to PAW for long-term applications on the skin surface. The in vitro anticancer effects of PAH in an artificial skin model were also better than those of PAW, reducing the viability of A375 cells without causing damage to HaCaT cells. Our study shows that PAH is superior to PAW in body-surface coating applications and can be used for subcutaneous anticancer applications. [ABSTRACT FROM AUTHOR]

A continuous risk from microbial infections poses a major environmental and public health challenge. As an emerging strategy for inhibiting bacterial infections, plasma‐activated water (PAW) has proved to be highly effective, environmental‐friendly, and non‐drug resistant to a broad range of microorganisms. However, the relatively short lifetime of reactive oxygen and nitrogen species (RONS) and the high spreadability of liquid PAW inevitably limit its real‐life applications. In this study, plasma‐activated hydrogel (PAH) is developed to act as reactive species carrier that allow good storage and controlled slow‐release of RONS to achieve long‐term antibacterial effects. Three hydrogel materials, including hydroxyethyl cellulose (HEC), carbomer 940 (Carbomer), and acryloyldimethylammonium taurate/VP copolymer (AVC) are selected, and their antibacterial performances under different plasma activation conditions are investigated. It is shown that the composition of the gels plays the key role in determining their biochemical functions after the plasma activation. The antimicrobial performance of AVC is much better than that of PAW and the other two hydrogels, along with the excellent stability to maintain the antimicrobial activity for more than 14 days. The revealed mechanism of the antibacterial ability of the PAH identifies the unique combination of short‐lived species (1O2, ∙OH, ONOO− and O2−) stored in hydrogels. Overall, this study demonstrates the efficacy and reveals the mechanisms of the PAH as an effective and long‐term disinfectant capable of delivering and preserving antibacterial chemistries for biomedical applications. [ABSTRACT FROM AUTHOR]

Plasma-activated water (PAW) is considered to be an effective anticancer agent due to the diverse aqueous reactive oxygen and nitrogen species (RONS: ROS and RNS), but the drawback of low dose and short duration of RONS in acidified PAW limits their clinical application. Herein, this Letter presents an innovative therapeutic avenue for cancer treatment with highly-effective alkaline PAW prepared by air surface plasma. This anticancer alkaline formulation is comprised of a rich mixture of highly chemical RONS and exhibited a prolonged half-life compared to acidified PAW. The H2O2, NO2−, and ONOO−/O2− concentrations in the alkaline PAW can reach up to 18-, 16-, and 14-fold higher than that in acidic PAW, and the half-life of these species was extended over 8-, 10-, and 26-fold, respectively. The synergistic potent redox action between these RONS with alkaline pH was shown to be more potent than acidic PAW for cancer cell inhibition in vitro. Furthermore, the alkaline PAW injection treatment also significantly inhibited tumor growth in tumor-bearing mice. The possible reasons are that the alkaline PAW would disturb the acid extracellular milieu leading to the inhibition of tumor growth and progression; moreover, the efficient and durable RONS with alkaline pH could induce significant cell apoptosis by altering cell biomolecules and participating apoptosis-related signaling pathways. These findings offer promising applications for developing a strategy with real potential for tumor treatment in clinical applications. [ABSTRACT FROM AUTHOR]

In this study, a microbubble‐enabled plasma reactor driven by a nanosecond‐pulsed generator was developed to provide an effective means for transferring highly reactive plasma species into liquids for plasma‐activated water (PAW) production. The physicochemical characteristics of PAW at different temperatures were evaluated, and the corresponding antimicrobial effects of PAW against Escherichia coli cells were investigated. Results show that the microbubble‐enabled PAW at a lower temperature (10°C) had the highest antimicrobial activity, resulting in a 2.43 ± 1.02‐log10 reduction of E. coli in PAW. The excellent energy efficiency of the total reactive oxygen and nitrogen species production in PAW is 10.37 g kW−1 h−1. Overall, this study provides much‐needed insights into the microbubble‐enabled plasma chemistries for optimizing the biochemical activity of PAW. [ABSTRACT FROM AUTHOR]

Enhancing virus multiplication could assist in the rapid production of vaccines against viral diseases. Cold atmospheric plasma (CAP), a physical approach relying on reactive oxygen species to achieve the desirable cellular outcome, was shown to be effective in enhancing virus propagation, where bovine rhinotrachieitis virus and Madin-Darby Bovine Kidney cells were used as the modeling virus and cell line, respectively. CAP was shown to create synergies with virus infection in arresting host cells at the G2/M stage, decreasing cell membrane potential, increasing intracellular calcium level, and inducing selective autophagy. In addition, CAP was demonstrated to suppress virus-triggered immunogenic signaling as evaluated by IRF7 expression. We presented evidences on CAP-triggered maximization of host resources toward virus multiplication that is advantageous for viral vaccine production, and opened a novel regime for applying CAP in the sector of medical care and health. [ABSTRACT FROM AUTHOR]

[Display omitted] • Underwater plasma bubbles were used to degrade cefixime in water. • Complete cefixime degradation with high-energy yield of 1.5 g/kWh. • Degradation of cefixime was conducted by reactive species, especially short-lived OH radicals. • Degradation pathways of cefixime were proposed by intermediates identified by LCMS. • Plasma treatment leads to the loss of antibacterial activity and cytotoxicity of cefixime. Excessive use and indiscriminate discharge of antibiotics inevitably lead to their accumulation in the environment, posing significant ecological and physiological risks. Non-thermal plasma (NTP) is receiving increasing attention as a sustainable technology for the efficient breakdown of these antibiotics as well as other contaminants. However, implementation of NTP technology still faces several hurdles, particularly the maximization of the reactive plasma effects and the practical scaling approaches. In this study, we generated NTP inside forming bubbles with enlarged gas-liquid interfacial areas for efficient delivery of reactive plasma species to target cefixime antibiotic molecules in aqueous solution. The degradation of cefixime was largely dependent on the different number of microholes, air flow rate, discharge power, plasma exposure time and solution properties. Results show that a high-performance degradation was achieved in the 10-microhole reactor with an energy yield of 1.5 g/kWh, after 30 min of plasma treatment. Based on LC-MS analysis, an NTP-initiated cefixime degradation pathway was proposed. Cytotoxicity studies demonstrated that the antibiotic activity of cefixime was effectively and wholly deactivated by the plasma process, and that no toxic effects of the 30 min-treated water were observed toward human cell lines. Furthermore, considering that air was employed as the inducer gas, which results in the formation of reactive nitrogen species in the water, the treated water was able to enhance seedling growth, further contributing to the societal and economic benefits of this plasma-based antibiotic degradation strategy. [ABSTRACT FROM AUTHOR]

Simple Summary: Cold atmospheric plasma (CAP) and plasma-activated medium (PAM) are known to selectively kill cancer cells, however the efficacy of CAP in cancer cells following epithelial-mesenchymal transition (EMT), a process which endows cancer cells with increased stemness, metastatic potential, and resistance to conventional therapies, has not been previously examined. We have used several established models of EMT to show that PAM is significantly more active in cancer cells exhibiting EMT than their epithelial counterparts. We further show that this enhancement correlated with increased levels of reactive oxygen species (ROS) in the mesenchymally-shifted cell lines. Cold atmospheric plasma (CAP) has emerged as a highly selective anticancer agent, most recently in the form of plasma-activated medium (PAM). Since epithelial–mesenchymal transition (EMT) has been implicated in resistance to various cancer therapies, we assessed whether EMT status is associated with PAM response. Mesenchymal breast cancer cell lines, as well as the mesenchymal variant in an isogenic EMT/MET human breast cancer cell system (PMC42-ET/LA), were more sensitive to PAM treatment than their epithelial counterparts, contrary to their responses to other therapies. The same trend was seen in luminal muscle-invasive bladder cancer model (TSU-Pr1/B1/B2) and the non-muscle-invasive basal 5637 bladder cancer cell line. Three-dimensional spheroid cultures of the bladder cancer cell lines were less sensitive to the PAM treatment compared to their two-dimensional counterparts; however, incrementally better responses were again seen in more mesenchymally-shifted cell lines. This study provides evidence that PAM preferentially inhibits mesenchymally-shifted carcinoma cells, which have been associated with resistance to other therapies. Thus, PAM may represent a novel treatment that can selectively inhibit triple-negative breast cancers and a subset of aggressive bladder cancers, which tend to be more mesenchymal. Our approach may potentially be utilized for other aggressive cancers exhibiting EMT and opens new opportunities for CAP and PAM as a promising new onco-therapy. [ABSTRACT FROM AUTHOR]

• Underwater plasma bubbles facilitated mass transfer of highly reactive species. • Plasma catalytic bubbles using CeO 2 enhanced the AP removal efficiency. • Catalytic performance and durability of CeO 2 were improved by plasma activation. • Degradation mechanisms of AP were proposed by intermediates identified by LCMS. Interactions between effects generated by non-thermal plasma (NTP) and catalysts are increasingly investigated, ranging from energy conversion and material synthesis to pollutant degradation (e.g. volatile organic compounds, VOCs) and water purification. To make the water ecosystem more environmentally and economically sustainable, green and efficient wastewater treatment technologies are urgently required. In this study, a plasmacatalytic bubble column reactor was designed to generate underwater plasma bubbles (PBs) for efficient delivery of plasma-produced gaseous reactive oxidative species to the liquid phase for subsequent applications. This system shows great potential for degrading a stubborn water contaminant azophloxine (AP), which was further enhanced with an addition of CeO 2 catalysts, resulting in the catalytic oxidation of the azo dyes. Moreover, the performances and durability of CeO 2 were further improved via plasma pre-activation. The plasma-treated CeO 2 (CeO 2 -P) displayed a combination of favourable properties, such as a higher concentration of oxygen vacancies and Ce3+ (observed by XPS), a narrowed energy bandgap, and an increased specific surface area (by 41.39%). Compared with the sole PBs and PBs/CeO 2 systems, the highest removal efficiency and kinetic constant up to 99.5% and 0.907 min−1, respectively, were achieved in the PBs/CeO 2 -P system. Reactive species trapping corroborated that ·OH and ·O 2 – played an integral part in AP degradation. Finally, intermediates in the process of AP degradation were identified and a degradation pathway was proposed. This research would offer a promising remediation methodology for water purification via the integration of underwater plasma bubbles and CeO 2 catalysts. [ABSTRACT FROM AUTHOR]

Complete degradation of mixtures of organic pollutants is a major challenge due to their diverse degradation pathways. In this work, a novel microplasma bubble (MPB) reactor was developed to generate plasma discharges inside small forming bubbles as an effective mean of delivering reactive species for the degradation of the target organic contaminants. The results show that the integration of plasma and bubbles resulted in efficient degradation for all azo, heterocyclic, and cationic dyes, evidenced by the outstanding energy efficiency of 13.0, 18.1 and 22.1 g/kWh with 3 min of processing, in degrading alizarin yellow (AY), orange II (Orng-II) and methylene blue (MB), individually. The MPB treatment also effectively and simultaneously degraded the dyes in their mixtures such as AY + Orng-II, AY + MB and AY + Orng-II + MB. Scavenger assays revealed that the short-lived reactive species, including the hydroxyl (OH) and superoxide anion (O 2 −) radicals, played the dominant role in the degradation of the pollutants. Possible degradation pathways were proposed based on the intermediate products detected during the degradation process. The feasibility of this proposed strategy was further evaluated using other common water pollutants. Reduced toxicity was confirmed by the observed increases in human cell viability for the treated water. This work could support the future development of high performance- and energy-efficient wastewater abatement technologies. Unlabelled Image • A plasma bubble column was developed for pollutant degradation. • Underwater microplasma bubbles facilitated mass transfer of reactive species. • Efficient and simultaneous degradation of dye mixtures was demonstrated. • Outstanding energy efficiency for pollutant degradation was obtained. [ABSTRACT FROM AUTHOR]

Microbial food contamination can be caused by bacteria, viruses or protozoa at different stages during food processing and storage. The resulting foodborne disease in humans are common and can be severe, especially in children, the elderly or immunocompromised persons. Several viruses have been recognised to account for a large proportion of foodborne illnesses, including human norovirus (HNoV) and hepatitis A virus (HAV). Disinfection methods are needed in all areas of the food processing environment and cold atmospheric plasma (CAP) has emerged as a new technology with antimicrobial activity. CAP is generated by applying an electric field to a gas causing the formation of many active species including reactive oxygen and nitrogen species. This review evaluates the available data on CAP as a potential use for the inactivation of foodborne viruses, including studies using surrogates. We demonstrate the different types of CAP delivery for virus inactivation, including direct and indirect treatments using dielectric barrier discharges (DBD), atmospheric pressure plasma jets (APPJ) and plasma-activated water (PAW). The effect of particular CAP species and the resulting mode of action is also discussed. CAP can successfully inactivate foodborne viruses and its potential as a non-toxic, residue-free sanitation system for fresh foods makes it highly attractive to the industry. However, the lack of standard devices or protocols makes it difficult to meaningfully translate findings. Thus, we propose future research steps that are necessary for upscaling, dose standardisation and following translation to the industry in the near future. • Cold atmospheric plasma (CAP) can successfully inactivate foodborne viruses. • Reactive oxygen and nitrogen species are important for viral inactivation. • Non-toxic, residue-free sanitation system is highly attractive to the food industry. • Standardisation of devices and treatment protocols is necessary for upscaling. [ABSTRACT FROM AUTHOR]

Atmospheric cold plasma (ACP) is an emerging non-thermal food sterilization technology. This study investigated the effects of ACP on the antioxidant membrane-bound triterpenoid carotenoid pigment (staphyloxanthin, STX) in S. aureus. Results showed that the survival rate of S. aureus in water (1.3 × 107 CFU/mL) after ACP treatment for 5, 10, 15, 20 min significantly decreased to 55.0%, 18.5%, 9.7% and 4.1%, accompanied by a decrease of STX content from 448.8 to 276.7, 80.3, 45.1 and 19.7 μg/mL, respectively. Particularly, 20-min ACP-treated S. aureus became more susceptible (4.79 times) to hydrogen peroxide (0.1 M) attack most probably due to the decrease of STX. ACP also caused a decrease in the cell membrane potential (MP), accumulation of intracellular reactive oxygen species (ROS), and cell necrosis. Pearson correlation analysis indicated that the survival rate, MP, intracellular ROS, and cell necrosis were all highly correlated to STX content, indicating that STX contributed to ACP-induced physiological alterations in S. aureus. These results demonstrated that STX was an important attack target during ACP inactivation of S. aureus. This study proposes a novel antibacterial mechanism of ACP against S. aureus from the perspective of STX, which would accelerate the development of ACP in food sterilization. Noting that pigmentation is a hallmark of multiple foodborne pathogenic microbes, this work shows the exciting potential of inactivating foodborne pathogens through destroying their intrinsic pigments. [Display omitted] • ACP could reduce staphyloxanthin (STX) content from 448.8 to 19.7 μg/mL and inactivate 95.9% of S. aureus in water. • ACP-pretreated S. aureus became more susceptible (4.79 times) to H 2 O 2 exposure most probably due to the decrease of STX. • STX concentration was highly correlated with survival rate, cell membrane potential, intracellular ROS, and cell necrosis. [ABSTRACT FROM AUTHOR]

The chemistry, antimicrobial efficacy and energy consumption of plasma-activated water (PAW) was optimized by altering the discharge frequency, ground-electrode configuration, gas flow rate and initial water conductivity for two reactor configurations, i.e., air pin-to-liquid discharge and air plasma-bubble discharge in water. The ratio of NO 2 − and NO 3 − formation was altered to optimise the antimicrobial effects of PAW, tested against two Gram-negative bacteria. An initial solution conductivity of 0.2 S·m−1 and 2000-Hz discharge frequency with the ground electrode positioned inside the pin reactor showed the highest antimicrobial effect resulting in a 3.99 ± 0.13-log 10 reduction within 300 s against Escherichia coli and 5.90 ± 0.24-log 10 reduction within 240 s for Salmonella Typhimurium. An excellent energy efficiency of reactive oxygen and nitrogen species (RONS) generation of 10.1 ± 0.1 g·kW−1·h−1 was achieved. Plasma-activated water (PAW) is deemed as an eco-friendly alternative to chemical disinfection because its bactericidal activity is temporary. Optimizing the design and operation of PAW reactors to achieve high inactivation rates of more than 5-log 10 reductions, as demonstrated in this work, will support the industrial application of this technology and the scaleup at industrial level. • Increasing discharge frequency from 1000 to 2000 Hz improved the antimicrobial characteristics of PAW by the pinreactor • Increasing initial liquid conductivity in the pin reactor increased the bacterial inactivation to 1.74–4.4-log 10 reduction • Ground electrode inside the pin reactor caused higher E. coli (3.99-) and S. Typhimurium (5.90-log 10 reduction) inactivations • Altering ground-electrode position from inside to outside the bubble reactor changed the NO 2 −/ NO 3 − ratio from 0.92 to 2.69 • The optimal PAW configuration, achieving more than 5-log reduction of S. Typhimurium , was the pin-to-liquid discharge [ABSTRACT FROM AUTHOR]