Use of the Cold Substrate Method for Biomaterials: The Structural and Biological Properties of the Ag Layers Deposited on Ti-6Al-4V

Silver nanofilms were vacuum-deposited on Ti-6Al-4V substrates at low (< 300 K) temperatures to improve their biocompatibility. After the surface of the Ti-6Al-4V samples was coated with Ag over the temperature range from 100 to 300 K, the structural and biological characteristics were investigated. The crystal structure of the Ag thin films was cubic with (111), (200), (220) and (311) peaks. The peak intensity of the Ag thin films increased with decreasing substrate temperature due to the formation of a closed surface structure and an increase in the Ag concentration (from 3.9 to 14.4%) and the film thickness (from 250 to 500 nm). The grain size of the Ag thin films decreased from similar to 300 to similar to 50 nm with decreasing substrate temperature. As the substrate temperature decreased, the surface morphology of the Ag films became homogeneous, and the surface roughness values decreased from 1.72 to 1.41 mu m. An increased corrosion resistance was obtained for the temperature range from 175 to 225 K due to a decrease in the corrosion current (from 1.96x10(-4) to 3.72x10(-6) A, respectively) and an increase in the corrosion potential (from - 0.95 to - 0.64 V, respectively). The biological response of the Ag deposited at 125 K was higher than that of the other samples, and the antibacterial activity of this sample was >= 99.99% after 3 h.