Investigation of the antimicrobial activity at safe levels for eukaryotic cells of a low power atmospheric pressure inductively coupled plasma source

Unraveling the permeation of reactive species across nitrated membranes by computer simulations

Reactive oxygen and nitrogen species (RONS) are involved in many biochemical processes, including nitro-oxidative stress that causes cancer cell death, observed in cancer therapies such as photodynamic therapy and cold atmospheric plasma. However, their mechanisms of action and selectivity still remain elusive due to the complexity of biological cells. For example, it is not well known how RONS generated by cancer therapies permeate the cell membrane to cause nitro-oxidative damage. There are many studies dedicated to the permeation of RONS across native and oxidized membranes, but not across nitrated membranes, another lipid product also generated during nitro-oxidative stress. Herein, we performed molecular dynamics (MD) simulations to calculate the free energy barrier of RONS permeation across nitrated membranes. Our results show that hydrophilic RONS, such as hydroperoxyl radical (HO₂) and peroxynitrous acid (ONOOH), have relatively low barriers compared to hydrogen peroxide (H₂O₂) and hydroxyl radical (HO), and are more prone to permeate the membrane than for the native or peroxidized membranes, and similar to aldehyde-oxidized membranes. Hydrophobic RONS like molecular oxygen (O₂), nitrogen dioxide (NO₂) and nitric oxide (NO) even have insignificant barriers for permeation. Compared to native and peroxidized membranes, nitrated membranes are more permeable, suggesting that we must not only consider oxidized membranes during nitro-oxidative stress, but also nitrated membranes, and their role in cancer therapies.

Cold Atmospheric Pressure Plasma Treatment Modulates Human Monocytes/Macrophages Responsiveness

Monocytes are involved in innate immune surveillance, establishment and resolution on inflammation, and can polarize versus M1 (pro-inflammatory) or M2 (anti-inflammatory) macrophages. The possibility to control and drive immune cells activity through plasma stimulation is therefore attractive. We focused on the effects induced by cold-atmospheric plasma on human primary monocytes and monocyte-derived macrophages. Monocytes resulted more susceptible than monocyte-derived macrophages to the plasma treatment as demonstrated by the increase in reactive oxygen (ROS) production and reduction of viability. Macrophages instead were not induced to produce ROS and presented a stable viability. Analysis of macrophage markers demonstrated a time-dependent decrease of the M1 population and a correspondent increase of M2 monocyte-derived macrophages (MDM). These findings suggest that plasma treatment may drive macrophage polarization towards an anti-inflammatory phenotype.

Effects and safety of atmospheric low-temperature plasma on bacterial reduction in chronic wounds and wound size reduction: A systematic review and meta-analysis

The use of atmospheric low‐temperature plasma (AP) on chronic wounds and its effect on microbial bioburden in open wounds has not been explored with a systematic review and meta‐analysis. PRISMA guidelines were followed and PubMed, Embase, CENTRAL, and CINAHL databases searched for randomised controlled trials (RCTs), which compared AP with no AP for the management of open, chronic wounds. The primary outcomes of reduction of bioburden or wound size were included. Meta‐analyses were performed; odds ratio (OR) and 95% confidence intervals (CIs) were extracted and pooled in a random effects model.

Four RCTs investigated the effect of AP on chronic wound healing. Chronic wounds treated with AP did not show a significant improvement in healing (AP vs control: OR = 1.46; 95% CI = 0.89‐2.38; P = 0.13). Five further RCTs investigated the reduction of bioburden in wounds, but AP demonstrated no significant reduction of bioburden (AP vs control: OR = 0.85; 95% CI = 0.45‐1.62; P = 0.63). All nine RCTs recorded the presence of any severe adverse events (SAEs) in the 268 patients studied, with only one unrelated SAE identified in each group (AP vs control: OR = 1.00; 95% CI = 0.05‐19.96; P = 1.00). Use of AP in wound care is safe, but the retrieved evidence and meta‐analysis show that there is no clinical benefit of AP in chronic open wounds using currently available AP device settings.

Atmospheric Pressure Pulsed Plasma Induces Cell Death in Photosynthetic Organs via Intracellularly Generated ROS

The toxicity of atmospheric-pressure pulsed plasma on plant leaf tissues is studied. A nanosecond-pulsed plasma jet is applied to Arabidopsis thaliana leaves. In case of cotyledon, cell death is induced by treatment of only a few seconds. Cell death is also induced in the adult leaf by only 5 seconds of plasma treatment. Plasma induced reactive oxygen species (ROS) accumulation across the tissues within plasma-treated area. Plasma also induced direct physical damage to epidermis tissue of treated area but merely no damage to mesophyll. Thus, we propose direct physical damage in epidermis and ROS accumulation across the treated area induced cell death by plasma treatment. Plasma treatment with same duration in different organ also induced ROS accumulation but not plant death, suggests damage on photosynthetic organ by oxidative stress might be direct reason to induce cell death. We could also observe similar plasma induced death in Solanum esculentum, Petunia axillaris, and Nicotiana benthamiana but death is induced only in treated area. Thus, we propose atmospheric plasma induce oxidative stress in photosynthetic organ to induce cell death in plants.