Cerium Ion-Incorporated Titanium Metal Implants of Enhanced Bioactivity for Biomedical Applications

The enhancement in the performance of metallic bone implants based on commercially pure titanium (CP-Ti) by incorporation of cerium (Ce) ions onto the surface was evaluated. The incorporation of Ce ions onto the CP-Ti surface was carried out by a simple two-step chemical treatment method, where an initial NaOH treatment and then a subsequent treatment with different molar concentrations of ceric nitrate solution followed by heat treatment at 600 °C were carried out. The modified surfaces were observed using field emission scanning electron microscopy (FE-SEM), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), X-ray photoelectron spectroscopy (XPS), the laser Raman spectroscopic technique, high-resolution transmission electron microscopy (HR-TEM), and atomic force microscopy (AFM). The formation of a nanonetwork structure by the initial NaOH treatment and the replacement of Na ions with Ce ions along with different phases of TiO₂ was evident from the surface characterization results. The transition of rutile TiO₂ to anatase TiO₂ in the modified surface is evident from the Raman spectra with respect to the treatment of higher to lower concentrations of ceric nitrate solution. The presence of two different oxidation states of Ce (Ce³⁺ and Ce⁴⁺) and improvement in the surface wettability were also distinct in the modified samples. Thus, the incorporated Ce ions over the nanostructured titania network showed low cytotoxicity, good cell adhesion, and enhanced extracellular mineralization on MG-63 cells with better protein adsorption in BSA medium. Taken together, the thus-improved nanostructured surface morphology with the anatase TiO₂ phase and distinct extracellular mineralization in the Ce-incorporated Ti metal with good biocompatibility make it a promising candidate for bone implant applications.