Plasma-liquid synthesis of MoOx and WO3 as potential photocatalysts.

Plasmas in contact with liquids represent a green chemistry method for the synthesis of metal oxides. In this work, underwater plasma was used for the synthesis of molybdenum and tungsten oxides. The obtained samples were analyzed by various techniques. Results showed that underwater plasma with Mo electrodes allows obtaining non-stoichiometric molybdenum oxide (MoOx). In the case of tungsten electrodes, monoclinic WO3 was formed. The synthesized oxides have a wide band gap (3.21 eV for MoOx and 3.27 eV for WO3). The photocatalytic and sorption activities of the synthesized oxides towards the decomposition of cationic and anionic dyes (Methylene Blue, Rhodamine B, and Reactive Red 6C) were studied. MoOx shows excellent photocatalytic performance under UV and visible light irradiation. The photocatalytic activity of WO3 under visible light is less than that under UV irradiation.

Cold Plasma-Treated Ringer's Saline: A Weapon to Target Osteosarcoma.

Osteosarcoma (OS) is the main primary bone cancer, presenting poor prognosis and difficult treatment. An innovative therapy may be found in cold plasmas, which show anti-cancer effects related to the generation of reactive oxygen and nitrogen species in liquids. In vitro models are based on the effects of plasma-treated culture media on cell cultures. However, effects of plasma-activated saline solutions with clinical application have not yet been explored in OS. The aim of this study is to obtain mechanistic insights on the action of plasma-activated Ringer's saline (PAR) for OS therapy in cell and organotypic cultures. To that aim, cold atmospheric plasma jets were used to obtain PAR, which produced cytotoxic effects in human OS cells (SaOS-2, MG-63, and U2-OS), related to the increasing concentration of reactive oxygen and nitrogen species generated. Proof of selectivity was found in the sustained viability of hBM-MSCs with the same treatments. Organotypic cultures of murine OS confirmed the time-dependent cytotoxicity observed in 2D. Histological analysis showed a decrease in proliferating cells (lower Ki-67 expression). It is shown that the selectivity of PAR is highly dependent on the concentrations of reactive species, being the differential intracellular reactive oxygen species increase and DNA damage between OS cells and hBM-MSCs key mediators for cell apoptosis.

Dual-Mode Solution Plasma Processing for the Production of Chitosan/Ag Composites with the Antibacterial Effect.

The development of novel biocompatible and biodegradable materials for medical applications has been drawing significant interest in the scientific community for years. Particularly, chitosan loaded with silver nanoparticles (Ag NPs) has a strong antimicrobial potential and could be applied, for example, as wound dressing material. In this work, chitosan/Ag NP composites were produced utilizing a single-step plasma-solution process, which is simple and environmentally friendly. An acetic solution of chitosan containing AgNO3 was treated by the direct current (DC) atmospheric pressure glow discharge, with the liquid serving as either cathode or anode. The plasma-solution system with liquid anode is more useful for the production of Ag NPs. Nevertheless, the NP size is comparable for both cases. The plasma treatment with both polarities led to chitosan degradation. The cleavage of glucosidic chains mostly occurred in the system with the liquid cathode, whereas the side oxidation reactions took place when the solution served as the anode. The oxidation processes were possibly induced by the hydrogen peroxide H2O2 efficiently formed in the last case. The composite materials produced with both polarities of liquid electrode demonstrated the bactericidal action against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and Gram-positive Bacillus subtilis.