Antibacterial burst-release from minimal Ag-containing plasma polymer coatings

Biomaterials releasing silver (Ag) are of interest because of their ability to inhibit pathogenic bacteria including antibiotic-resistant strains. In order to investigate the potential of nanometre-thick Ag polymer (Ag/amino-hydrocarbon) nanocomposite plasma coatings, we studied a comprehensive range of factors such as the plasma deposition process and Ag cation release as well as the antibacterial and cytocompatible properties. The nanocomposite coatings released most bound Ag within the first day of immersion in water yielding an antibacterial burst. The release kinetics correlated with the inhibitory effects on the pathogens Pseudomonas aeruginosa or Staphylococcus aureus and on animal cells that were in contact with these coatings. We identified a unique range of Ag content that provided an effective antibacterial peak release, followed by cytocompatible conditions soon thereafter. The control of the in situ growth conditions for Ag nanoparticles in the polymer matrix offers the possibility to produce customized coatings that initially release sufficient quantities of Ag ions to produce a strong adjacent antibacterial effect, and at the same time exhibit a rapidly decaying Ag content to provide surface cytocompatibility within hours/days. This approach seems to be favourable with respect to implant surfaces and possible Ag-resistance/tolerance built-up.