Dual surface modification strategies for enhanced osteogenesis of titanium through the biomimetic Haversian osteon with deposited CaP to assemble salidroside.

Titanium (Ti) and Ti alloy are the most widely used implant metals, but the limited bioactivity hinders the further clinical application. Aiming to enhance their osteogenesis, dual biomimetic strategies were utilized to decorate the surface of Ti by topological and biochemical cues. Firstly, a series of concentric circles with TiO nanotubes on Ti were fabricated by photolithography and anodic oxidation. Furthermore, hydrothermal deposition and vacuum adsorption were adopted to introduce CaP and then assemble natural product of salidroside (Sal) on TiO nanotubes (Sal/CaP/BTNT). Sal/CaP/BTNT was not only bio-mimicked the features of Haversian osteon in size and composition, but also slowed the release of Sal simultaneously. This biomimetic Haversian osteon induced bone marrow mesenchymal stem cells (BMSCs) to grow along the concentric circles, and was involved in BMP, Wnt/β-catenin, Notch and mechanical signaling pathways. Particularly, the expressions of related genes were up-regulated nearly to 200 % in mechanical signaling pathway compared to that of pure BMSCs. Additional, Sal enhanced osteogenic differentiation of BMSCs via BMP signaling pathway. The dual biomimetic Haversian osteon could promote the proliferation, differentiation and mineralization of BMSCs compared to that of pure BMSCs. In vivo studies showed that the CaP/BTNT and Sal/CaP/BTNT both promoted more new-bone formation than that of the control groups, indicating of their accelerated osseointegration due to the dual biomimetic Haversian osteon. The dual biomimetic strategies endowed Ti the excellent osteogenesis, which provided a promising surface modification strategy of Ti and Ti alloy to accelerate osteogenesis in clinic.