This study presents investigations to create antibacterially active thin films by using the atmospheric pressure plasma chemical vapor deposition technique. Silver nitrate solutions are sprayed and converted within the plasma to create and implement formed silver nanoparticles into a growing SiOx‐matrix in situ during the deposition step. Investigation of the films on their bactericidal activity using an Escherichia coli (E. coli) strain shows a strong antibacterial effect of the coatings and additionally a good stability against abrasive wear. The films are characterized by X‐ray photoelectron spectroscopy, SEM, energy dispersive X‐ray spectroscopy, and IR spectroscopy. magnified image
Objectives: Plasma medicine focuses on the application of cold atmospheric pressure plasmas (CAPs) in or on the human body. So far, plasmas have been used to sterilize implant materials or other thermally unstable medical products and have been applied for chemical surface modifications. This study investigates the antimicrobial effect of physical plasmas on microorganisms which cause skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans, depending on the plasma source and the kind of plasma excitation used. Materials: Microorganisms were plated onto MH2 agar plates. Plasma treatment was performed using the plasma sources BLASTER MEF and kinpen 09. To investigate the antimicrobial effects, the following plasma parameters have been varied: working gas, distance from nozzle to surface, electrical power, grid spacing of treatment lines, number of treatments and work piece velocity. Results: The generated plasmas had an antimicrobial effect that depended on the chosen plasma parameters, in particular on the process gas used, the plasma power and the number of treatments performed. Thus, different reactive species were observed by optical emission spectroscopy measurement in the generated plasmas. Conclusions: The study showed that CAPs exhibit profound bactericidal and fungicidal properties in vitro. However, an important factor for the antimicrobial efficacy is the composition of the ‘chemical soup' supplied by the CAP system which can be regulated by the process gases used.
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.
The aim of this study was to test the possibilities of using APCVD and CCVD to create effective antibacterial coatings and to determine their antibacterial activity. SiOx‐layers were created by use of a hexamethyldisiloxane (HMDSO) precursor in combination with silver nitrate solution and silver nanoparticles as additives. A strong antibacterial effect of the APCVD and CCVD coated samples on an Escherichia coli (E. coli) strain could be shown. Layers obtained by CCVD showed a longer‐lasting antibacterial activity. The results were verified using a commercially available microbial cell viability assay basing on the measurement of bacterial adenosine triphosphate (ATP) or by counting of colony forming units (CFU) on agar plates.
The study showed that CAPPs demonstrate strong bactericidal and fungicidal properties in vitro. The selective application of CAPPs for the treatment of wound infections may offer a promising supplementary tool alongside current therapies.
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