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The combined application of ultrasound (US) and plasma microbubble (PMB) is a promising technology against glioblastoma (GBM). Here, we determined the effects of US and PMB (alone and combined) on U‐251 MG GBM and A431 epidermoid carcinoma spheroids under different conditions. The synergistic treatment of US‐ and PMB‐induced tumor sphere cell death in a time‐, dose‐, treatment frequency‐, and reactive oxygen species dependent manner, while multiple treatments augmented this effect. Synergistic treatments significantly reduced three‐dimensional GBM spheroid regrowth and cell proliferation while inducing cytotoxicity, spheroid shrinkage, and damage to the tumor microenvironment. PMB‐induced cytotoxicity throughout the tumor sphere, likely via long‐lived reactive oxygen and nitrogen species (H2O2, NO2−, and NO3−) and other reactive species. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate whether sonoporation of cancer cells using ultrasound (US) technology could enhance the anticancer effects of cold atmospheric plasma. US‐induced transient sonoporation of cancer cells with little to no cytotoxicity observed on the cell lines tested. Synergistic effects of US were observed when combined with both direct and indirect cold atmospheric plasma. These cytotoxic effects were dependent on reactive species production. To the best of our knowledge that is the first time that the effects of those two nonthermal technologies were evaluated in cancer cells, demonstrating a promising combined strategy for cancer therapies, particularly for those with penetration limitations, such as glioblastoma. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of a pin‐to‐plate cold atmospheric plasma (CAP) on U‐251 MG three‐dimensional (3D) glioblastoma spheroids under different conditions. 3D tumorspheres showed higher resistance to the CAP treatment compared to 2D monolayer cells. A single CAP treatment was able to induce cytotoxicity, while multiple CAP treatments augmented this effect. CAP was also able to induce cytotoxicity throughout the tumoursphere, and we identified that reactive oxygen species (ROS) plays a major role, while H2O2 plays a partial role in CAP‐induced cytotoxicity in tumourspheres. We conclude that ROS‐dependent cytotoxicity is induced uniformly throughout glioblastoma and epidermoid tumourspheres by direct CAP treatment. [ABSTRACT FROM AUTHOR]

A large gap pin‐to‐plate, atmospheric‐pressure plasma reactor is demonstrated as means of in vitro study of plasma species interactions with cell cultures. By employing optical emission and optical absorption spectroscopy, we report that the pin‐to‐pate plasma array had an optimal discharge frequency for cell death of 1000 Hz in ambient air for the target cancer cell line, human glioblastoma multiform (U‐251MG). The detected plasma chemistry contained reactive oxygen and nitrogen species including OH, N2, N2+ and O3. We show that by varying the plasma discharge frequency, the plasma chemistry can be tailored to contain up to 8.85 times higher levels of reactive oxygen species (ROS) as well as a factor increase of up to 2.86 for levels of reactive nitrogen species (RNS). At higher frequencies, ROS are more dominant than RNS, which allows for a more dynamic and controlled environment for sample study without modifying the inducer gas conditions. When used for treatment of culture media and cell cultures, variation of the plasma discharge frequency over the range 1000–2500 Hz demonstrated a clear dependence of the responses, with the highest cytotoxic responses observed for 1000 Hz. We propose that the reactor offers a means of studying plasma–cell interactions and possible cofactors such as pro‐drugs and nanoparticles for a large volume of samples and conditions due to the use of well plates. [ABSTRACT FROM AUTHOR]

A plasma's working gas is a significant factor affecting their discharge characteristics and the induced chemistries during plasma–water interactions. However, the effects on the discharge mode and discharge stability have not been fully investigated. This study focuses on the discharge mode transition and stability with nitrogen and oxygen gases. Compared with the oxygen discharge, the nitrogen discharge remained stable over a larger voltage range and long duration time. A diffuse mode discharge had better stability and lower plasma activity for both nitrogen and oxygen gases, whereas a transient spark mode in nitrogen and filament mode in oxygen had lower stability but a higher plasma activity. This study improves the understanding of the physicochemical processes of plasma–water interactions. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate that atmospheric air plasma bubbles are an effective, energy‐efficient, residue‐free alternative to current decontamination techniques. Five to fifteen minutes of plasma‐bubble treatments of inoculated chicken skin led to a significant reduction in colony‐forming units (CFUs). We show that the activation efficiency is dependent on the plasma discharge frequency, with a higher one (2,000 Hz) leading to a higher CFU reduction (1.4 log) as compared with a lower (0.3 log) reduction at 1,000 Hz. Scanning electron microscopy pictures of treated bacteria reveal damage to the cells. An evaluation of the physicochemical properties of the generated plasma‐activated water revealed an increase in conductivity and in ozone, nitrite, nitrate, hydroxyl, and peroxide concentrations with higher frequencies, all contributing to the observed antimicrobial effect. [ABSTRACT FROM AUTHOR]

This work provides an insight into the generation of excited nitrogen species by allowing noble gases to interact both with one another and ambient air. He and Ar were utilized to generate the optimum selectivity process to create reactive nitrogen species. An optimum setting for the generation of excited molecular nitrogen species, based on their excited energy levels, was obtained when using a mixture of Ar‐He at a ratio of 10:1. At that point, when a voltage of 27 kV is applied to the system, it reached the maximum efficiency for selectivity processes to occur which allowed for a greater non‐radiative transfer of energy through the mixture of noble gas atoms and into the molecular nitrogen present in ambient air. [ABSTRACT FROM AUTHOR]

Atmospheric air plasma has previously been shown to be a novel and effective method for biofilm eradication. Here we study the effects of plasma on both microbial inactivation and induced structural modification for forming biofilms. New structures are created from aggregates of extracellular polysaccharides and dead bacterial cells, forming a protective and resilient matrix in which the remaining living cells grow and reproduce under proper growth conditions. The new colonies are found to be more resilient in this state, reducing the efficacy of subsequent plasma treatment. We verify that the observed effect is not caused by chemicals produced by plasma reactive species, but instead by the physical processes of drying and convection caused by the plasma discharge. [ABSTRACT FROM AUTHOR]

The potential of cold plasma as a food processing aid has been demonstrated for a range of processes and products. The potential applications of plasma technology are extensive and include microbial decontamination, pest control, toxin elimination, food and package functionalisation and many others. However, studies reported to date have principally been at laboratory scale. This paper discusses the status and challenges of transferring the technology to the industry. The major challenges discussed for adoption of atmospheric plasma as a food processing tool by industry are (1) demonstration of product/process specific efficacies; (2) development of process compatible technology designs and scale‐up; (3) effective process control and validation; (4) regulatory approval; and (5) consumer acceptance. [ABSTRACT FROM AUTHOR]

Plasma-activated liquids (PAL) attract increasing interest with demonstrated biological effects. Plasma exposure in air produces stable aqueous reactive species which can serve as chemical diagnostics of PAL systems. Here, we tailor aqueous reactive species inside plasma-activated water (PAW) through treating water with AC air spark and glow discharges in contact with water. Chemical probing demonstrated species specificity between two types of PAW. Spark discharge PAW contains [ABSTRACT FROM AUTHOR]

Recent reports indicate that atmospheric cold plasma (ACP) treatment of seeds can enhance their germination, however, the mechanisms of action are not yet entirely clear. In the present work, we report on the effects of plasma treatment on wheat seed germination and seedling growth. Additionally, changes in the surface chemistry and characteristics of the wheat seeds exposed to plasma were investigated. Treatments of 30–60 s significantly enhanced the germination rate and showed positive effects on seedling growth. ACP resulted in changes of seed surface and chemical characteristics including water uptake and contact angle values. Changes in seed pH and total titratable acidity, as well as nitrites, nitrates, and malondialdehyde concentrations were also recorded. [ABSTRACT FROM AUTHOR]

Front Cover: The cold plasma‐based inner‐surface decontamination is of particular relevance to biofouling of pipelines, both industrial and clinical. A helium porous plasma jet based on gas diffuser was designed, with the aim of decontaminating inner surfaces of relevant contaminated structures. The porous plasma jet operates with discharge modes in ambient air and inside vessels. Its decontamination capacity is demonstrated by inactivation efficacy of Pseudomonas aeruginosa biofilm as a well characterised biofilm model. Further details can be found in the article by Peng Lu, Dana Ziuzina, Patrick J. Cullen, and Paula Bourke (e1800055). [ABSTRACT FROM AUTHOR]

We present a helium porous plasma jet based on gas diffuser, designed with the aim of decontaminating inner surfaces of contaminated structures, e.g., pipes. The porous plasma jet operates with three discharge modes in ambient air and inside a vessel. Its decontamination capacity is demonstrated by evaluating the inactivation efficacy of biofilm form of Pseudomonas aeruginosa, adherent to inner surface of a glass vial. Plasma treatments for 5 min with filament mode and double region helium discharge mode reduced bacterial numbers by 2.4 and 2.5 Log10 CFU/ml. Plasma treatment with double region air‐like discharge mode was the most effective, reducing bacterial cells by 4.5 Log10 CFU/ml, which demonstrates porous plasma jet could provide an efficient approach for inner surface decontamination. A helium porous plasma jet has been presented. With the proper discharge mode, it significantly inactivates Pseudomonas aeruginosa biofilm adherent to the inner surface of a glass vial by greater than 4 Log10 CFU/ml. The porous plasma jet presented can provide an efficient alternative for the inner surface sterilization in relevant sectors, such as medical device, food and pharmacy industries. [ABSTRACT FROM AUTHOR]