title: Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity.
abstract: Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr+Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5% (w/v) NaClO solution for 5 min. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at.% of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the film's surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release.
authors.affiliation: GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal; CEB, Centre for Biological Engineering, LIBRO-Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Campus of Gualtar, 4700-057 Braga, Portugal. Electronic address: isabelferreri@gmail.com.
authors.forename: I
authors.initials: I
authors.lastname: Ferreri
authors.affiliation: GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal; CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Calderon V
authors.affiliation: Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, 28049 Madrid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Escobar Galindo
authors.affiliation: Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Palacio
authors.affiliation: CEB, Centre for Biological Engineering, LIBRO-Laboratório de Investigação em Biofilmes Rosário Oliveira, University of Minho, Campus of Gualtar, 4700-057 Braga, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Henriques
authors.affiliation: CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra, Portugal.
authors.forename: A P
authors.initials: AP
authors.lastname: Piedade
authors.affiliation: GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal; CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Carvalho
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D020099:Coated Materials, Biocompatible; D003486:Cyanides / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D012834:Silver / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D020099:Coated Materials, Biocompatible; D003486:Cyanides; D012834:Silver; D015040:Zirconium
keywords: Bacterial adhesion; Biomaterial; Silver activation; Sputtering