Mesenchymal Stem Cells Adhesion on Micro-to-Nano-Scaled Hierarchical Ti Implants Fabricated by Powder Metallurgy and Anodization

Abstract

The osseointegration of titanium (Ti) implants highly depends on their surface properties, including roughness, wettability and composition. Ti surfaces with micron-scale roughness have demonstrated more rapid bone apposition compared with polished ones. Besides, Ti implants with nanostructured surface also exhibit better cell adhesion and proliferation behavior. However, the optimal surface for bone regeneration is still unknown, partly due to the difficulty in fabricating surfaces with highly reproducible micron-and nanotopography. In this study, Ti implants with two hierarchies of roughness were fabricated by powder metallurgy, followed by anodization treatment to obtain self-assembled TiO2 nanotubes on the micro-roughened surface. X-ray diffraction (XRD), scanning electron microscopy (SEM), 3D Laser Scanning Microscope (3D LSM), and fluorescence microscope were used to investigate the properties of the samples. Ra of the powder metallurgy surface was about 5 μm, while, nanotubes of around 100 nm in diameter were observed after the anodization process. Compared with the reference samples, i.e., the ones with either smooth or single-level-structure surfaces, the ones with micro-to-nanoscaled hierarchical topography exhibited lower contact angle, higher protein adsorption and significantly improved mesenchymal stem cells (MSCs) early adhesion.