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Honolulu, Hawaii, United States, 2006/10/03 - Researchers in Germany developed a new method for producing antibacterial metal/polymer nanocomposite coatings, where silver and gold nanoparticles are only incorporated in a thin surface layer.
The potential use of antiimicrobial surface coatings ranges from medicine, where medical device infection is associated with significant healthcare costs, to the construction industry and the food packaging industry. Thin films which contain silver have been seen as promising candidate coatings. Silver is known as one of the oldest antimicrobial agents. Silver ions are thought to inhibit bacterial enzymes and bind to DNA. Silver has been used effectively against different bacteria, fungi and viruses. Researchers in Germany developed a new method for producing antibacterial metal/polymer nanocomposite coatings, where silver and gold nanoparticles are only incorporated in a thin surface layer. The new material shows a greatly enhanced antibacterial efficiency of the thin films.
Dr. Vladimir Zaporojtchenko, from the Chair for Multicomponent Materials at the University of Kiel in Germany,explained the new findings to Nanowerk: "We developed a new co-deposition process based on sputtering to protect a surface against growth of bacteria by depositing a thin nanocomposite film consisting of silver particles in a fluoropolymer matrix. The well-known antibacterial activity of silver is greatly enhanced by depositing an additional very thin layer of gold clusters. The much more effective release of silver ions form the coating is attributed to the combination of clusters of silver with clusters of the nobler gold."
Zaporojtchenko is first author of a recent paper, titled "Physico-chemical and antimicrobial properties of co-sputtered Ag–Au/PTFE nanocomposite coatings", that was published in the September 11, 2006 online edition of Nanotechnology.
Different silver-based approaches for preventing microbial adhesion have been proposed previously. However, the resulting materials have shown controversial or sometimes disappointing clinical results. Conventional ionic silver preparations such as silver nitrate are quickly inactivated in biological fluids because different biologically inactive complexes are formed. Other techniques like impregnation of silver in the bulk material lead to ineffective use of the expensive impregnated silver particles and decrease of the antibacterial efficiency because of the longer diffusion lengths of the bulk materials. As a result, large quantities of silver cannot be used to provide antimicrobial activity.
"It is therefore necessary to optimize the antimicrobial coating according to defined silver ion release and to required time" says Zaporojtchenko. "Therefore, it seems more effective to use nanocomposite coatings with embedded silver nanoparticles, which provide a very large effective surface for metal ion release."
Read the full article on the Nanowerk website.
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By Michael Berger, Copyright 2006 Nanowerk, LLC