Antibacterial activities and biocompatibilities of Ti-Ag alloys prepared by spark plasma sintering and acid etching

In this work, Ti-Ag sintered alloys (Ti-Ag) with different Ag contents were prepared by a spark plasma sintering (SPS) technique, which is a new, efficient and convenient method of powder metallurgy. The Ti-Ag samples were then treated with a mixture of 40 wt% hydrofluoric acid (HF) and nitric acid (HNO3). The surface features, ion release, antibacterial activities and biocompatibilities of the acid-etched Ti-Ag (Ti-Ag(AE)) samples were systematically characterized. The surface characterization results revealed the formation of micropits and particles with high Ag contents. Antibacterial experiments demonstrated that the antibacterial ratios of the Ti-Ag samples increased significantly after the acid etching treatment, and the particles with high Ag contents are thought to play a key role in the antibacterial mechanism. Biocompatibility experiments indicated that the cell proliferation, cell morphology, and osteoblastic differentiation did not significantly differ between the pure titanium (cp-Ti) and Ti-Ag(AE) samples. The Ti-Ag(AE) samples with 3 wt% and 5 wt% Ag not only possessed sustained antibacterial activities for at least 30 days but also did not have impaired biocompatibility.