Characterization and antibacterial performance of ZrNO-Ag coatings

Composite metal nitride-metal (MeN-Me) physical vapor deposited (PVD) films (e.g. TaN-Cu, TiN-Cu, ZrN-Ag, etc.) are often considered for applications such as tribological and antibacterial coatings. In this study, ZrN, ZrO₂-Ag and ZrNO-Ag coatings with different Ag contents were deposited by reactive magnetron sputtering. Monoclinic ZrO₂ and fcc Ag composite structures were obtained when Zr and Ag were cosputtered to react with oxygen. ZrNO-Ag showed a porous structure containing monoclinic ZrO₂, fcc Ag and Zr₂ON₂. Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) and Staphylococcus aureus (S. aureus), major pathogens frequently found in the implant-associated infections, were cultured on the coated samples. The antibacterial effects were determined using in vitro anti-bacterial analyses by a fluorescence staining method employing Syto9 and bacterial viability agar tests. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated by a MTT test assay. It showed that the nanostructure and Ag content of the ZrO₂-Ag and ZrNO-Ag coatings were correlated with the biocidal property. The ZrN coating deposited by magnetron sputtering did not improve the bacterial reduction of A. actinomycetemcomitans and S. aureus. The ZrO₂-Ag and ZrNO-Ag coated samples had lower bacterial retention, and the ZrNO-Ag coatings with silver content of 11.8at.% possessed the best antibacterial performance with excellent HGF cell compatibility as well.