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Antimicrobial effects and dissolution properties of silver copper mixed layers

: Gotzmann, G.; Jorsch, C.; Wetzel, C.; Funk, H.W.R.


Surface and coatings technology 336 (2018), S.22-28
ISSN: 0257-8972
Fraunhofer FEP ()
silver; copper; mixed coating; Escherichia coli; antibacterial; dissolution

Within the last years, research in the areas of hygiene and healthcare has focused on the resurgence of antimicrobial coatings to prevent infections and control their spreading. We used a physical vapor deposition technology to deposit coatings of either silver or copper individually or as mixtures on flexible polymeric substrates. Five combinations of silver and copper coatings were produced with a thickness of 50. nm. The respective amounts of silver and copper on the coated surfaces were determined using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX). The antimicrobial characteristics of silver and copper against Escherichia coli K12 (E. coli) were investigated, focusing on the possible synergistic effects of the two metals. The deposited coatings showed homogeneous mixtures of silver and copper clusters. The mixtures of silver and copper as well as pure silver showed antimicrobial properties. In contrast, pure copper did not exhibit antimicrobial effects. The dissolution behavior of copper and silver was determined by incubation of mixed layers in physiological media (synthetic sweat). Copper coatings proofed to be fully dissolvable whereas silver showed lower solubility. With increasing copper content in the mixed coatings, the dissolution of silver increased as well. The observed dissolution behavior was correlated to the results of the antimicrobial activity of the investigated coatings.