Surfaces modified with nanometer-thick silver-impregnated polymeric films that kill bacteria but support growth of mammalian cells

Ankit Agarwal, Tahlia L. Weis, Michael J. Schurr, Nancy G. Faith, Charles J. Czuprynski, Jonathan F. McAnulty, Christopher J Murphy, Nicholas L. Abbott

Research output: Contribution to journalArticle

204 Scopus citations

Abstract

Silver is widely used as a biocidal agent in ointments and wound dressings. However, it has also been associated with tissue toxicity and impaired healing. In vitro characterization has also revealed that typical loadings of silver employed in ointments and dressings (~100 μg/cm2) lead to cytotoxicity. In this paper, we report the results of an initial study that sought to determine if localization of carefully controlled loadings of silver nanoparticles within molecularly thin films immobilized on surfaces can lead to antimicrobial activity without inducing cytotoxicity. Polymeric thin films of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) were prepared by layer-by-layer deposition and loaded with ~0.4 μg/cm2 to ~23.6 μg/cm2 of silver nanoparticles. Bacterial killing efficiencies of the silverloaded films were investigated against Staphylococcus epidermidis, a gram-positive bacterium, and it was determined that as little as ~0.4 μg/cm2 of silver in the polymeric films caused a reduction of 6 log10 CFU/mL (99.9999%) bacteria in suspensions incubated in contact with the films (water-borne assays). Significantly, whereas the antibacterial films containing high loadings of silver were found to be toxic to a murine fibroblast cell line (NIH-3T3), the polymeric films containing ~0.4 μg/cm2 of silver were not toxic and allowed attachment, and growth of the mammalian cells. Thus, the results of this study go beyond prior reports by identifying silver-impregnated, polymeric thin films that are compatible with in vitro mammalian cell culture yet exhibit antibacterial activity. These results support the hypothesis that localization of carefully controlled loadings of silver nanoparticles within molecularly thin polymeric films can lead to antimicrobial activity without cytotoxicity. More broadly, this strategy of modifying surfaces with minimal loadings of bioactive molecules indicates the basis of approaches that may permit management of microbial burden in wound beds without impairment of wound healing.

Original languageEnglish (US)
Pages (from-to)680-690
Number of pages11
JournalBiomaterials
Volume31
Issue number4
DOIs
StatePublished - 2010
Externally publishedYes

Keywords

  • Antibacterial activity
  • Cytotoxicity
  • Nanostructured polymer films
  • Silver nanoparticles
  • Wound healing wound-bed engineering

ASJC Scopus subject areas

  • Biomaterials
  • Bioengineering
  • Ceramics and Composites
  • Mechanics of Materials
  • Biophysics

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