A comparative antibacterial activity and cytocompatibility for different top layers of TiN, Ag or TiN-Ag on nanoscale TiN/Ag multilayers

Surface modification is considered to be an important approach for improving the antibacterial activity and cytocompatibility of titanium alloys. Silver has been extensively studied for improving the antibacterial ability of implants due to its powerful antibacterial activity. Therefore, in this study, TiN/Ag multilayers were deposited on the surface of medical titanium alloys by a multi-arc ion plating system with the top TiN, Ag, and TiN and Ag composite (TiN-Ag) layers. The structure and chemical characteristics of the three groups were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. Scanning electron microscopy (SEM) was used to elucidate the cross-section structures of the multilayers. The surface topography, roughness, friction coefficients, hardness and elastic modulus values for different top layers were obtained by atomic force microscopy (AFM), wear tester and nanoindenter. The biological assays, including cytocompatibility experiments and antibacterial activity, were evaluated by MC3T3-E1 cells, bovine serum albumin (BSA) and Escherichia coli. (E. coli) in vitro. These results confirm that the TiN/Ag multilayers with the exposed TiN-Ag top layer show excellent mechanical properties, antibacterial properties and ideal cytocompatibility, leading to the potential application of these multilayers as body-implanted materials.