Abstract: In this study, anodization and hydrothermal treatment techniques were first employed to prepare Sr2+-loaded TiO2 nanotube arrays on the titanium surface. Then, carboxymethyl chitosan (CMCS) coating was fabricated on the nanotube surface by electrophoretic deposition. Finally, NO-releasing molecules (N-Nitroso-N-phenylhydroxylamine ammonium salt, Cupferron) and osteogenic growth peptides (OGP) were sequentially loaded into the nanotubes, achieving synergistically promoting osteoblast adhesion, proliferation, and functional expression by Sr2+, NO gas molecule, and OGP. The results indicated that the functionalized nanotube arrays could not only induce biomimetic deposition of hydroxyapatite (HA), but also continuously release Sr2+ and NO gas signaling molecules, significantly promoting the adhesion and growth of osteoblasts, as well as the expressions of alkaline phosphatase (ALP), osteocalcin (OCN), and Runt related transcription factor 2 (RUNX2). After loading OGP, the osteoblast adhesion, growth, and functional expression were further enhanced. Therefore, the surface modification strategy of the present study can be used to construct the bioactive coating with excellent biocompatibility on titanium alloy surfaces to improve the bone integration ability of titanium-based bone-substituted materials.

Key words: Titanium, Osteoblast, NO gas molecule