title: Silver nanoparticles and polymeric medical devices: a new approach to prevention of infection?
abstract: OBJECTIVE
  Implantable devices are major risk factors for hospital-acquired infection. Biomaterials coated with silver oxide or silver alloy have all been used in attempts to reduce infection, in most cases with controversial or disappointing clinical results. We have developed a completely new approach using supercritical carbon dioxide to impregnate silicone with nanoparticulate silver metal. This study aimed to evaluate the impregnated polymer for antimicrobial activity.
  
  
  METHODS
  After impregnation the nature of the impregnation was determined by transmission electron microscopy. Two series of polymer discs were then tested, one washed in deionized water and the other unwashed. In each series, half of the discs were coated with a plasma protein conditioning film. The serial plate transfer test was used as a screen for persisting activity. Bacterial adherence to the polymers and the rate of kill, and effect on planktonic bacteria were measured by chemiluminescence and viable counts. Release rates of silver ions from the polymers in the presence and absence of plasma was measured using inductively coupled plasma mass spectrometry (ICP-MS).
  
  
  RESULTS
  Tests for antimicrobial activity under various conditions showed mixed results, explained by the modes and rates of release of silver ions. While washing removed much of the initial activity there was continued release of silver ions. Unexpectedly, this was not blocked by conditioning film.
  
  
  CONCLUSIONS
  The methodology allows for the first time silver impregnation (as opposed to coating) of medical polymers and promises to lead to an antimicrobial biomaterial whose activity is not restricted by increasing antibiotic resistance.
authors.affiliation: Biomaterials-Related Infection Group, School of Medical and Surgical Sciences, University of Nottingham, Nottingham NG7 2UH, UK.
authors.forename: Franck
authors.initials: F
authors.lastname: Furno
authors.forename: Kelly S
authors.initials: KS
authors.lastname: Morley
authors.forename: Ben
authors.initials: B
authors.lastname: Wong
authors.forename: Barry L
authors.initials: BL
authors.lastname: Sharp
authors.forename: Polly L
authors.initials: PL
authors.lastname: Arnold
authors.forename: Steven M
authors.initials: SM
authors.lastname: Howdle
authors.forename: Roger
authors.initials: R
authors.lastname: Bayston
authors.forename: Paul D
authors.initials: PD
authors.lastname: Brown
authors.forename: Peter D
authors.initials: PD
authors.lastname: Winship
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Reid
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D001672:Biocompatible Materials; D002245:Carbon Dioxide; D006801:Humans; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry*; D019736:Prostheses and Implants / Q000382:microbiology*; D012826:Silicone Elastomers / Q000737:chemistry / Q000494:pharmacology*; D012834:Silver / Q000737:chemistry / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000517:prevention & control; D013212:Staphylococcus epidermidis / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D001672:Biocompatible Materials; D012826:Silicone Elastomers; D002245:Carbon Dioxide; D012834:Silver