1α,25-Dihydroxyvitamin D3-loaded hierarchical titanium scaffold enhanced early osseointegration.

Accelerated osseointegration is well considered as a critical facilitated factor for titanium scaffold longevity，but immensely limited by bioinert material surfaces and restricted biological responses in vivo. Here, we fabricated three-dimensional printed porous titanium scaffold modified with titanium dioxide (TiO2) nanotubes (p-TNTs), for mimicking the hierarchical trabecular bone structure and building local drug delivery system to accelerate osseointegration. The scaffold at macro and micro gradient was manufactured by selective laser melting process with pure titanium powder according to the computer-aided design (CAD), which could be further anodized to construct nano-gradient frameworks and drug-loading districts. Sequentially, 1α,25-Dihydroxyvitamin D3 (VD3) was loaded into anodized TiO2 nanotubes，thermo-sensitive hydrogel Pluronic F-127 (F-127) was coated and charged as a bio-cap for control release. Biological responses in vitro and in vivo was evaluated, showing significant osteogenesis enhancement of hierarchical structure with local drug delivery. It suggests that a promising bioactive implant system may provide a far-reaching impact on accelerating and enhancing early osseointegration.