Comparison of Effects of Calcium and Magnesium Doping on the Structure and Biological Properties of NaTaO3 Film on Tantalum

Tantalum is widely used in hip joint replacement and knee joint repair, but its clinical application is limited due to its poor biological activity and weak ability to promote new bone formation. Ca and Mg ions are thought to be involved in bone metabolism and play an important physiological role in the angiogenesis, growth, and mineralization of bone tissue. In this work, NaTaO3 films doped with Ca2+ and Mg2+ were prepared by hydrothermal synthesis and molten salt method. The doping amounts of Ca2+ doped at 450, 550, 650 and 750 °C were 0.59, 3.44, 32.75 and 29.88 at%, and that of Mg2+ doped at 300, 350, 400, 450, 500, 550 and 650 °C were 0.62, 1.03, 1.54, 20.12, 21.38, 14.37 and 0.74 at%, respectively. Ca2+ and Mg2+ are evenly incorporated into NaTaO3 and cause the change of crystal plane spacing without any significant changes of morphologies below 550 and 400 °C respectively. XPS shows that the cations are the A-site substitution of perovskite structure (ABO3). According to the morphology and composition analysis of Ca-incorporated samples and Mg-incorporated samples, the optimal preparation temperature of them is 550 °C and 400 °C, respectively. The results show that for “550 °C-Ca” and “400 °C-Mg” the hydrophilicity is 13.9° and 96.1°, the roughness is 114.3 and 54.3 nm, the doping ion concentration of Ca and Mg is 3.44 and 1.54 at%, and the 7-day ICP results is 69.8 and 1.4 ppm, respectively. In addition, cell proliferation experiments and cell morphology related to biological activity and osteogenic properties are discussed, and it is found that the performance of “550 °C-Ca” is better than “400 °C-Mg”. Ca2+–NaTaO3 is a promising implantable material that will be extensive used in bone implants, joint replacements and dental implants.