Biphasic calcium phosphates/tantalum pentoxide hybrid layer and its effects on corrosion resistance and biocompatibility of titanium surface for orthopedic implant applications

Our aim in this study was to enhance the corrosion resistance and biocompatibility of Ti surfaces by producing a multifunctional hybrid layer of biphasic calcium phosphates (BCPs)/tantalum pentoxide (Ta₂O₅) on Ti surfaces for orthopedic implant applications. It is known that the biological response to calcium phosphate is exceptional; the stability of Ta₂O₅ is superior to that of the TiO₂ which forms spontaneously on Ti and its alloys. In this study, a simple hydration-condensation process was first used to create a Ta₂O₅ layer on Ti surfaces. We then applied a bioactive BCPs layer over the Ta₂O₅ layer using a rapid electrochemical cathodic deposition process. The resulting hybrid layer with satisfactory adherence was shown to greatly enhance the corrosion resistance of Ti in simulated blood plasma, while also promoting the surface hydrophilicity, bioactivity, and bone cell adhesion. Our results indicate that the inner Ta₂O₅ layer provides good resistance to corrosion, while the bioactive outer BCPs layer further enhances not only the corrosion resistance but also the in vitro biocompatibility. These characteristics make the proposed hybrid layer on Ti surfaces ideal for potential orthopedic implant applications.