Influence of Ag/Ca ratio on the osteoblast growth and antibacterial activity of TiN coatings on Ti-6Al-4V by Ag and Ca ion implantation

Titanium nitride (TiN) coating has many prominent properties such as chemical stability, high hardness, excellent wear properties, biocompatibility and so on, which make it as a potential candidate for inhibiting the release of toxic ions and improving mechanical properties of dental and orthopedic implants made by titanium-aluminum-vanadium (Ti-6Al-4V). Of course, the biologically inert and poor antibacterial property of TiN limits its application. In this work, TiN coating was firstly deposited on the surface of Ti-6Al-4V substrate to inhibit its toxic ions release. Then, silver (Ag) and calcium (Ca) with different ratios were implanted into TiN coatings by plasma immersion ion implantation and deposition (PIII&D) system to enhance both osteoblast growth and antibacterial activity on the surfaces of TiN coatings. The results show that TiN coating inhibits the release of toxic ions such as Al and V. X-ray photoelectron spectrometer (XPS) and X-ray diffraction (XRD) analyses proved the presence of Ag, Ca on the surface of Ag and Ca implanted TiN (Ag/Ca-TiN). Scanning electron microscopy (SEM) was used to observe the surfaces' morphologies of samples, which takes advantage of distinct detectors to visualize secondary and back-scattering electrons. The protein adsorption experiment showed that the protein adsorption capacities increased with the increase of Ca ratio. When the results of antibacterial and cell adhesion tests were combined, Ag/Ca(2:1)-TiN indicated the best osteoblast adhesion and antibacterial activity in vitro due to the synergistic effect of Ag and Ca. The improved inhibiting ability in releasing toxic ions, osteoblast adhesion and antibacterial activity of the Ag/Ca(2:1)-TiN suggest that it might be a potential choice for surface medication of orthopedic implants clinically.