Porous titanium scaffolds with self-assembled micro/nano-hierarchical structure for dual functions of bone regeneration and anti-infection.

Porous titanium (Ti) scaffolds are widely used for bone repair because of their good biocompatibility, mechanical properties, and corrosion resistance. However, pristine Ti scaffolds are bioinert and unable to induce bone regeneration. In this study, chitosan coated bovine serum albumin nanoparticles (CBSA NPs) and oxidized alginate (OSA) were in a layer-by-layer (LbL) manner on Ti scaffolds. The LbL film possessed micro/nano-hierarchical architectures, has the features of nanostructures, and possesses abundant functional groups from CBSA NPs and OSA to improve the surface biocompatibility and biofunctionality of Ti scaffolds. These groups provide active sites for stable and efficient immobilization of bone morphogenic protein-2 (BMP2) through chemical and physical interactions without compromising its bioactivity. The synergistic effect of the hierarchical structure of assembled films and immobilized BMP2 on the scaffold improves cell adhesion, proliferation, and induces osteogenic differentiation of bone marrow stromal cells in vitro. Moreover, this modification also enhances ectopic bone formation bone. Furthermore, grafting of vancomycin on OSA resulted in good antibacterial activity of Ti scaffolds for prevention of infection during the bone healing process. In summary, this NPs-assembling method is convenient and effective to produce nanostructures and to load growth factors and antibacterial agents into Ti scaffolds for bone tissue engineering.