Plasma Treated Water Solutions (PTWS) recently emerged as a novel tool for the generation of Reactive Oxygen and Nitrogen Species (ROS and RNS) in liquids. The presence of ROS with a strong oxidative power, like hydrogen peroxide (H2O2), has been proposed as the main effector for the cancer-killing properties of PTWS. A protective role has been postulated for RNS, with nitric oxide (NO) being involved in the activation of antioxidant responses and cell survival. However, recent evidences proved that NO-derivatives in proper mixtures with ROS in PTWS could enhance rather than reduce the selectivity of PTWS-induced cancer cell death through the inhibition of specific antioxidant cancer defenses. In this paper we discuss the formation of RNS in different liquids with a Dielectric Barrier Discharge (DBD), to show that NO is absent in PTWS of complex composition like plasma treated (PT)-cell culture media used for in vitro experiments, as well as its supposed protective role. Nitrite anions (NO2-) instead, present in our PTWS, were found to improve the selective death of Saos2 cancer cells compared to EA.hy926 cells by decreasing the cytotoxic threshold of H2O2 to non-toxic values for the endothelial cell line.

Magnesium plays a pivotal role in the formation, growth, and repair of bone tissue; therefore, magnesium-based materials can be considered promising candidates for bone tissue engineering. This study aims to functionalize the surfaces of three-dimensional (3D) porous poly-ε caprolactone (PCL) scaffolds with magnesium-containing coatings using cold plasma-assisted deposition processes. For this purpose, the radiofrequency (RF) sputtering of a magnesium oxide target was carried out in a low-pressure plasma reactor using argon, water vapor, hydrogen, or mixtures of argon with one of the latter two options as the feed. Plasma processes produced significant differences in the chemical composition and wettability of the treated PCL samples, which are tightly related to the gas feed composition, as shown by X-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) analyses. Cytocompatibility assays performed with Saos-2 osteoblast cells showed that deposited magnesium-containing thin films favor cell proliferation and adhesion on 3D scaffold surfaces, as well as cell colonization inside them. These films appear to be very promising for bone tissue regeneration.

Reactive oxygen and nitrogen species (RONS) can be generated in liquids by different cold plasma processes. These species can influence cell biology and pathological states, and trigger wound healing, disinfection, and cancer treatments. The optimization of plasma sources' configurations and experimental conditions is fundamental to dose-produced RONS in liquids. This research is a case study comparing RONS generation (H 2 O 2 and NO 2 − ) in water, after exposure to two different atmospheric pressure cold dielectric barrier discharge (DBD) plasma sources: a plasma jet-DBD and a planar-DBD operating in contact with the liquid and in remote, respectively. The data demonstrate that the reactor geometry and the treatment modality strongly impact the generation of the active species in water.