Influence of Ag alloying on the antibacterial properties, bio-corrosion resistance and biocompatibility of α-Nb5Si3 nanocrystalline coating

To improve the corrosion resistance and impart the bioactivity and antibacterial functionalities to titanium alloys for biomedical applications, alpha-(Nb1-xAgx)(5)Si-3 compounds, with three different Ag contents, were deposited on Ti-6A1-4V by double cathode glow discharge method. The new alpha-(Nb1-xAgx)(5)Si-3 coatings, each about 16 im in thickness, exhibited a compact uniform structure, composed of equiaxed nanocrystalline grains. Nanoindentation measurements revealed that Ag alloying reduced the hardness (H) and elastic modulus (E) values of the alpha-(Nb1-xAgx)(5)Si-3 coatings. Compared to Ti-6A1-4V, the alpha-(Nb1-xAgx)(5)Si-3 coatings exhibited improved corrosion resistance in Ringer's physiological solution, as well as newly added in-vitro bioactivity and antibacterial ability against both E. coll. and S. aureus. A MTT assay experiment shows that the two alpha-(Nb1-xAgx)(5)Si-3(x = 0 and 0.05) coatings were as non-cytotoxic as bare Ti-6A1-4V. However, the MC3T3-E1 osteoblastlike cell viability for the alpha-(Nb0.9Ag0.1)(5) Si s coating was slightly reduced, suggesting that the proliferation of MC3T3-E1 osteoblast-like cell was affected to some degree by excess Ag added to alpha-Nb5Si3. Overall, the alpha-(Nb0.9Ag0.1)(5) Si s coating provides an attractive combination of good bioactivity, high corrosion resistance and new antibacterial function, and thus demonstrates great potential for applications in orthopedic devices.