Cold Atmospheric Plasma Exerts Antimicrobial Effects in a 3D Skin Model of Cutaneous Candidiasis.

Cutaneous candidiasis is characterized by an overgrowth of Candida leading to skin inflammation and infection. Similar to bacteria, Candida can develop tolerance to common antifungal drugs. Cold atmospheric plasma (CAP), with its proven antimicrobial properties, offers a promising alternative to the prevailing methods. Because of plasma heterogeneity each new device must be tested individually for its effectiveness. Antimicrobial activity is usually studied using planktonic microorganisms or animal models, making it difficult to extrapolate the results to the human system. Therefore, a 3D skin model of cutaneous candidiasis for the antimicrobial testing of CAP was established. First, the reaction of the 3D-skin model to Candida infection was examined using various histological and molecular-biological methods. Infection with C. albicans resulted in increased expression and secretion of pro-inflammatory cytokines and augmented expression of antimicrobial peptides. Within 48 h, hyphal growth spread throughout the model and caused tissue damage. Second, the CAP treatment was employed. It was shown that CAP significantly reduced the spread of the yeast in the infected skin models as well as decreased the expression and secretion of the infection markers. The plasma device exhibited a high antifungal activity by completely inhibiting hyphal growth and reducing inflammation at the highest treatment duration.

Antibacterial Silicon Oxide Thin Films Doped with Zinc and Copper Grown by Atmospheric Pressure Plasma Chemical Vapor Deposition.

Zn-doped and Cu-doped SiOx films were synthesized by atmospheric pressure plasma chemical vapor deposition to study their antibacterial efficiency against Gram-negative Escherichia coli and their cytotoxic effect on the growth of mouse cells. Zn-rich and Cu-rich particles with diameters up to several microns were found to be homogeneously distributed within the SiOx films. For both doping elements, bacteria are killed within the first three hours after exposure to the film surface. In contrast, mouse cells grow well on the surfaces of both film types, with a slight inhibition present only after the first day of exposure. The obtained results indicate that the films show a high potential for use as effective antibacterial surfaces for medical applications.

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.