Dose- and Time-Dependent Cellular Effects of Cold Atmospheric Pressure Plasma Evaluated in 3D Skin Models.

BACKGROUND: Application of cold atmospheric pressure plasmas (CAPs) in or on the human body was termed 'plasma medicine'. So far, plasmas were utilized for sterilization of implants, other heat-sensitive products, or employed for chemical surface modifications. By now, CAPs are further used effectively for wound treatment. The present study analyses the effect of a plasma jet with air or nitrogen as process gas, previously evaluated for antimicrobial efficacy, on human cells using a 3D skin model. METHODS: CAP treatment of 3D skin models consisting of a keratinocyte-containing epidermal layer and a fibroblast/collagen dermal matrix was performed using the Tigres plasma MEF technology. To evaluate the effects on the 3D skin models, the following plasma parameters were varied: process gas, input power, and treatment time. RESULTS: Low CAP doses exhibited good cell compatibility. Increasing input power or elongating treatment intervals led to detrimental effects on 3D skin model morphology as well as to release of inflammatory cytokines. It was further observed that air as process gas was more damaging compared to nitrogen. CONCLUSIONS: Treatment of 3D skin models with the plasma MEF nozzle using air or nitrogen is reported. A clearly dose- and time-dependent effect of CAPs could be observed in which the CAP based on nitrogen exhibited higher cell compatibility than the CAP generated from air. These settings might be recommended for medical in vivo applications such as wound decontamination.

Atmospheric pressure plasma CVD as a tool to functionalise wound dressings.

The main goal of this investigation was the preparation of an antibacterial layer system for additional modification of wound dressings with atmospheric plasma. Furthermore, the modified wound dressings were checked on there bactericidal and cytotoxic activity. The layer system was applied by using a novel atmospheric pressure plasma chemical vapour deposition technique on a variety of textile substrates which are suitable as wound dressing materials. The layer system composed of silicon dioxide with in situ generated embedded silver nanoparticles. The bactericidal activity of the produced wound dressings was investigated against different bacteria like Staphylococcus aureus and Klebsiella pneumoniae while the cytotoxic potential of the coated wound dressings was verified using human keratinocytes. Even at low concentrations of silver precursor a strong antibacterial effect was observed in direct contact with S. aureus and K. pneumoniae. Furthermore, extractions produced from the coated textiles showed a good antibacterial effect. By means of optimised coating parameters a therapeutic window for those wound dressings could be identified. Consequently, the atmospheric pressure plasma chemical vapour deposition technique promise an effective and low cost modification of wound dressing materials.

Pure, transparent-melting starch esters: synthesis and characterization.

Long chain starch esters were prepared by a new method using molten imidazole as solvent for the biopolymer. The advantage is the simplicity of the reaction mixture. Imidazole is acting not only as solvent, but also as reagent and base. The reaction succeeds via the imidazolide, which is formed in situ with an acid chloride. It yields highly pure derivatives, as could be shown by NMR spectroscopy and elemental analysis. No hints for desoxychloro substituents or other impurities could be found. The high quality of the products prepared is responsible for the occurrence of colorless melts. Although DSC measurements show a variety of thermal transitions, the formation of melts in the range of 40 to 255 °C could be observed with a hot stage microscope. The melting behavior can be adjusted by the type of ester moiety and the amount of ester functions introduced. In case of starch palmitates completely transparent melts are obtained within two distinct DS regions namely around 1.5 and 2.2 to 3.0. Upon cooling the melts form homogeneous films on different supports including glass. They show good adhesion and should therefore be a suitable basic material for the preparation of composites like laminated glass.