Silver activation on thin films of Ag–ZrCN coatings for antimicrobial activity

• Published in: Materials Science & Engineering C 2015-10, Vol.55 (C), p.547-555
• Main Authors: Ferreri, I., Calderon V., S., Escobar Galindo, R., Palacio, C., Henriques, M., Piedade, A.P., Carvalho, S.
• Format: Article
• Language: English
• Subjects: Activation; Activation analysis; Anti-Infective Agents - chemistry; Anti-Infective Agents - pharmacology; Antiinfectives and antibacterials; Austenitic stainless steels; Bacterial adhesion; Biomaterial; Coated Materials, Biocompatible; Coatings; Cyanides - chemistry; Failure; Heat resistant steels; Microscopy, Electron, Scanning; Photoelectron Spectroscopy; Science & Technology; Silver; Silver - chemistry; Silver activation; Sputtering; Staphylococcus epidermidis; Surface chemistry; Surgical implants; Thin films; Zirconium - chemistry
• ISSN: 0928-4931; 1873-0191; 0928-4931
• DOI: 10.1016/j.msec.2015.05.071

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 316L, 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 5min. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11at.% 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. •Silver activation is a simple and low cost process to silver ionization enhancement.•Silver particle shape and cover ratio were changed after the activation procedure.•Ag–ZrCN coatings showed antimicrobial effect after the silver activation procedure.•Antimicrobial activity attributed to silver oxidation and ion release to the medium.