A hierarchically graded bioactive scaffold bonded to titanium substrates for attachment to bone

In this paper we report a Ti-based, hierarchical porous scaffold anchored to Ti substrates, prepared by synthesizing hydroxyapatite-calcium carbonate-Ti three-layer spheres and combining a modified plasma spraying process and an anodic oxidation treatment. The hierarchical porous scaffolds were composed of 100-350 μm interconnecting macropores, 0.2-90 μm pores and ∼100 nm nanopores with >70% porosity. At the same time, the scaffolds also had the graded structures constructed by bioactive TiOx in surface transforming to metallurgy-bondable Ti in bottom. Mechanical property tests demonstrated that the porous scaffolds had similar Young's modulus with natural bone and strong bonding strength with the Ti substrates. The simulate body fluid immersion showed that bone-like apatite layer could form rapidly at scaffold surface. The in vitro cell incubation demonstrated that the porous scaffolds had good cellular compatibility and could correctly regulate cascade gene expression of primary osteoblasts. The intramuscular implantations indicated the porous scaffolds had high osteoinductivity and the bone implantations demonstrated that the scaffolds could facilitate new bone growth and have strong bonding strength with surrounding bone.