Andreas Pfuch

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.

Thin antimicrobial silver, copper or zinc containing SiO x films on wood polymer composites (WPC) applied by atmospheric pressure plasma chemical vapour deposition (APCVD) and sol–gel technology

Microbial colonization of wood and wood polymer composites (WPC) by bacteria and mould can cause aesthetic damage, negative impact on mechanical properties or even health hazards. This work investigated the structural morphology, elemental composition and antimicrobial properties of thin functional silicon oxide films deposited on WPC using atmospheric pressure chemical vapour deposition (APCVD) and sol–gel technology. Scanning electron microscopy results indicated the creation of flat, thin and closed films on top of the surface of this material. By embedding of active agents such as silver, copper or zinc, the APCVD films became slightly rougher. The corresponding sol–gel-films showed a certain number of cracks. The elemental composition of the films was investigated by X-ray photoelectron spectroscopy and depth profiling indicating the integration of active agents into the created SiOx film matrices. Moreover, the possibility to generate combinations of active agents in one layer could be demonstrated. BacTiter-Glo® tests as a part of antibacterial investigations showed strong bactericidal properties for silver and copper as well as sufficient properties for zinc-containing layers against Escherichia coli. Antimycotic effects on mould strains Aspergillus niger, Paecilomyces variotii, Penicillium funiculosum and Trichoderma viride were low for films containing only one active agent. Significant improvements in activity were achieved by the combination of these active agents.

Normal Pressure CVD - an Easy and Sustainable Method for Technical Surface Functionalisation

The PYROSIL ® technique is a well known process which is used to produce SiOx layers by using Combustion Chemical Vapour Deposition (C-CVD) in order to modify surfaces and their properties like the adhesion promotion. Another method to deposit oxides at atmospheric pressure is the use of potential free plasmas like plasma blaster or plasma jets for the decomposition of the precursors (AP-CVD). As precursors liquid and gaseous compounds or suspensions with nanoparticles can be used, which are pyrolysed by flame or plasma. The process energy especially during the flame treatment serves additional as a heating source for the substrate. The APor C-CVD coatings have the potential for several different applications e.g. antireflective coatings on glass for solar industry, antimicrobial or photo catalytic coatings. Current results and several different aspects for the application of this technology will be presented.

Wie Klebungen einfacher validiert werden können

Mit einer neuartigen Zentrifugentechnik [1, 2] wird der Zugversuch, der bisher nur als Ein-Proben-Prüfung unter Verwendung einer Zugprüfmaschine durchgeführt werden konnte, nun als Mehr-ProbenPrüfung in einer analytischen Zentrifuge realisiert. Damit können die Klebfestigkeit von Klebverbindungen, die Haftfestigkeit von Beschichtungen [3] und die Verbundfestigkeit von Kompositwerkstoffen untersucht werden. Die Idee dabei: Die Proben müssen zur Prüfung nicht mehr beidseitig eingespannt, sondern nur noch einseitig unterstützt werden, wodurch ein einfaches Einstecken der zu prüfenden Proben ausreichend ist. Zudem können bis zu acht Proben gleichzeitig unter identischen Bedingungen geprüft werden. Bezüglich der Validierung von Klebverbindungen lag es nahe, die hiermit gegebene Möglichkeit der Mehr-Proben-Prüfung auch auf die Mehr-Proben-Fähigkeit der Prozessschritte Vorbehandlung und Kleben zu erweitern.