Synergistic effects of oxidative and acid stress on bacterial membranes of Escherichia coli and Staphylococcus simulans.

Oxidative stress in combination with acid stress has been shown to inactivate a wide spectrum of microorganisms, including multi-resistant bacteria. This occurs e.g.

Electrical properties determine the liquid flow direction in plasma-liquid interactions.

During atmospheric pressure plasma impingement, plasma induced liquid flow will influence the transport and distribution of plasma generated charged and reactive species in liquids. We use particle image velocimetry and supplementary pH, conductivity and temperature measurements to investigate electrical properties of an AC kHz plasma jet interacting with water and electrolytes. We observe that the dominant driving mechanism in low conductive solutions are surface forces such as shear stresses and stagnation-pressure induced dimpling.

Two separate mechanisms are involved in membrane permeabilization during lipid oxidation.

Lipid oxidation is a universal degradative process of cell membrane lipids that is induced by oxidative stress and reactive oxygen and nitrogen species (RONS) in multiple pathophysiological situations. It has been shown that certain oxidized lipids alter membrane properties, leading to a loss of membrane function. Alteration of membrane properties is thought to depend on the initial membrane lipid composition, such as the number of acyl chain unsaturations.

Towards plasma jet controlled charging of a dielectric target at grounded, biased, and floating potential.

Electric field and surface charge measurements are presented to understand the dynamics in the plasma-surface interaction of a plasma jet and a dielectric surface. The ITO coated backside of the dielectric allowed to impose a DC bias and thus compare the influence of a grounded, biased and floating potential. When imposing a controlled potential at the back of the target, the periodical charging is directly dependent on the pulse length, irrespective of that control potential.

Quantification of surface charging memory effect in ionization wave dynamics.

The dynamics of ionization waves (IWs) in atmospheric pressure discharges is fundamentally determined by the electric polarity (positive or negative) at which they are generated and by the presence of memory effects, i.e. leftover charges and reactive species that influence subsequent IWs.

Antibacterial and safety tests of a flexible cold atmospheric plasma device for the stimulation of wound healing.

Cold atmospheric plasma (CAP) devices generate an ionized gas with highly reactive species and electric fields at ambient air pressure and temperature. A flexible dielectric barrier discharge (DBD) was developed as an alternative antimicrobial treatment for chronic wounds. Treatment of Staphylococcus aureus in collagen-elastin matrices with CAP for 2 min resulted in a 4 log reduction.

Safety and bactericidal efficacy of cold atmospheric plasma generated by a flexible surface Dielectric Barrier Discharge device against Pseudomonas aeruginosa in vitro and in vivo.

Background: Cold atmospheric plasma (CAP), which is ionized gas produced at atmospheric pressure, could be a novel and potent antimicrobial therapy for the treatment of infected wounds. Previously we have shown that CAP generated with a flexible surface Dielectric Barrier Discharge (sDBD) is highly effective against bacteria in vitro and in ex vivo burn wound models. In the current paper, we determined the in vitro and in vivo safety and efficacy of CAP generated by this sDBD device.

In-situ monitoring of an organic sample with electric field determination during cold plasma jet exposure.

Pockels-based Mueller polarimetry is presented as a novel diagnostic technique for studying time and space-resolved and in-situ the interaction between an organic sample (a layer of onion cells) and non-thermal atmospheric pressure plasma. The effect of plasma is complex, as it delivers electric field, radicals, (UV) radiation, non-uniform in time nor in space. This work shows for the first time that the plasma-surface interaction can be characterized through the induced electric field in an electro-optic crystal (birefringence caused by the Pockels effect) while at the same moment the surface evolution of the targeted sample is monitored (depolarization) which is attached to the crystal.

Revealing Plasma-Surface Interaction at Atmospheric Pressure: Imaging of Electric Field and Temperature inside the Targeted Material.

The plasma-surface interaction is studied for a low temperature helium plasma jet generated at atmospheric pressure using Mueller polarimetry on an electro-optic target. The influence of the AC kHz operating frequency is examined by simultaneously obtaining images of the induced electric field and temperature of the target. The technique offers high sensitivity in the determination of the temperature variation on the level of single degrees.