No abstract

The application of non‐thermal (cold) plasmas in medicine holds great promise. Non‐thermal plasma devices have been used to directly ablate cells, induce apoptosis, facilitate cell transfection, lay down bioscafolds, and sterilize heat sensitive materials. Although the reactive species (RS) generated by the plasmas have been implicated in all of these processes, the biological mechanisms of action are poorly understood and the potential adverse effects largely unknown. In this work, we used a parallel electrode dielectric barrier discharge (DBD) and the atmospheric pressure glow discharge torch (APGD‐t) to assess the possible negative effects of direct and indirect plasma treatment of mammalian cells and naked DNA. HeLa cells demonstrated an oxidative stress response when placed in direct contact with the plasma. No lipid peroxidation resulted from the application of the plasma to the cells. Both plasma sources were shown to be able to fragment naked DNA in PBS and to cause DNA double‐strand breaks (DSBs). Sequencing of treated plasmid DNA introduced into electrocompetent bacterial cells showed no evidence of mutations. We conclude that the reactive nature of non‐thermal plasmas can create oxidative stresses and may have unintended negative biological effects on cells.

A miniature nonthermal atmospheric plasma jet was used to deposit patterns of plasma polymers on standard Pyrex Petri dishes from an argon/acetylene gas mixture. The injection of the C 2 H 2 monomer through the powered capillary electrode ending in the nozzle section allowed a stable operation of the plasma jet and the successful deposition of plasma-polymer tracks ≈500 μm wide. The line-averaged gas temperature was measured from the OH molecular band emission originating from the entrainment of air into the plasma jet. The gas temperature decreased monotonically from ≈440 K at the nozzle exit to ≈385 K at 5 mm downstream. The emission profiles of the C 2 (516 nm) band showed a peak ≈0.5 mm downstream the nozzle exit. The maximum emission for the CH band (431 nm) was obtained at the torch exit. An ATR-FTIR spectroscopy analysis of the deposited plasma-polymer films revealed the presence of C-H, O-H, and C = O functional groups. Mammalian cells grown on the argon/acetylene plasma-treated dishes showed migration and greater density compared to the control and dishes treated with an argon plasma jet. This preliminary study opens the door to the localized enhancement of cell coverage on various substrates (shape and material).Index Terms-Atmospheric pressure glow discharge (APGD) jet, cell growth and proliferation, plasma polymer, plasma spectroscopy.

BackgroundTransferring genes and drugs into cells is central to how we now study, identify and treat diseases. Several non-viral gene therapy methods that rely on the mechanical disruption of the plasma membrane have been proposed, but the success of these methods has been limited due to a lack of understanding of the mechanical parameters that lead to cell membrane permeability.MethodsWe use a simple jet of inert gas to induce local transfection of plasmid DNA both in vitro (HeLa cells) and in vivo (chicken chorioallantoic membrane). Five different capillary tube inner diameters and three different gases were used to treat the cells to understand the dependency of transfection efficiency on the dynamic parameters.ResultsThe simple setup has the advantage of allowing us to calculate the forces acting on cells during transfection. We found permeabilization efficiency was related to the dynamic pressure of the jet. The range of dynamic pressures that led to transfection in HeLa cells was small (200 ± 20 Pa) above which cell stripping occurred. We determined that the temporary pores allow the passage of dextran up to 40 kDa and reclose in less than 5 seconds after treatment. The optimized parameters were also successfully tested in vivo using the chorioallantoic membrane of the chick embryo.ConclusionsThe results show that the number of cells transfected with the plasmid scales with the dynamic pressure of the jet. Our results show that mechanical methods have a very small window in which cells are permeabilized without injury (200 to 290 Pa). This simple apparatus helps define the forces needed for physical cell transfection methods.

These data demonstrate that the skin surface is primarily hydrophobic and paradoxically becomes more wettable through its lipidic component, especially the sebum. Emulsions seemed to interact with the skin and change its CST as would do their continuous phase only.