Surface immobilization of gelatin onto TiO₂ nanotubes to modulate osteoblast behavior

To improve the bioactivity of titanium implants, a homogeneous layer of TiO₂ nanotubes with a diameter of approximately 110nm was prepared by anodization. Gelatin was immobilized onto TiO₂ nanotubes through an intermediate layer of polydopamine. The surface characteristics of different substrates were evaluated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements, respectively. These results demonstrate that gelatin was successfully immobilized onto TiO₂ nanotubes. In vitro cell culture experiments including immunofluorescence staining, cell viability, alkaline phosphatase (ALP), mineralization and the expression of osteogenic genes including runt-related transcription factor 2 (Runx2), ALP, collagen type I (Col I), and osteopontin (OPN) confirm that cell spreading, proliferation and osteoblastic differentiation were improved when cells were seeded onto gelatin-immobilized TiO₂ nanotubes. This resulting material shows great promise as a future material in titanium implant applications.