Influence of Ag content on the antibacterial properties of SiC doped hydroxyapatite coatings

The main goal of the paper is to enhance the resistance to the bacteria of the hydroxyapatite deposited on Ti6Al4V alloy substrate. Hydroxyapatite coatings, enriched with SiC and Ag, were prepared and investigated for this paper. SiC was added to enhance film corrosion resistance, while by Ag addition the improvement of the antibacterial properties was foreseen. The coatings, with different Ag contents, were deposited on Ti6Al4V alloy substrates by co-sputtering of hydroxyapatite, SiC and Ag targets, using a magnetron sputtering system. The films were characterized in terms of elemental and phase composition, texture, morphology, corrosion resistance and antibacterial activity (Staphylococcus aureus MRSA, Staphylococcus aureus ATCC 29213, Streptococcus pyogenes ATCC 19615, Salmonella Typhimurium ATCC 14028), by EDS, XRD, FTIR, SEM and AFM techniques, electrochemical tests and antimicrobial tests. The influence of the Ag content on the film properties was also analysed. The antibacterial efficacies of hydroxyapatite versus Gram-positive bacteria are demonstrated if a small amount of Ag was added in their structure. The hydroxyapatite with Ag content less than 1 at% proves to have a good resistance to the bacteria attack, even if the content is reduced. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.