Sol-Gel Fabricated Tio₂ Coating on Titanium Surface Promoted In Vitro Osteoblasts Differentiation

Titanium has been used for biomedical devices due to its excellent biocompatibility, which is based partly on its 2-8 nm thick titanium oxide layer. However, the relatively poor surface hardness, wear resistance and metal release of these layers may cause some problems in clinical application. In this study, titanium surfaces were modified using a TiO₂ sol-gel coating, in order to improve surface properties and osteoblast function. No significant difference in surface roughness was observed between titanium and TiO₂ sol-gel discs. The surface of TiO₂ sol-gel discs possessed more wettability than titanium discs. The X-ray diffraction results showed amorphous TiO₂ phase on titanium discs, whereas TiO₂ sol-gel surfaces presented TiO₂ rutile and anatase phase. After 4 hours, the number of osteoblasts seeded on TiO₂ surface was significantly higher than those on titanium discs. The mRNA expression of bone sialoprotein and osteocalcin were also higher on day 5 and 7, respectively. Enzyme-linked immunosorbent assay(ELISA) analysis confirmed the increase of osteocalcin protein synthesis in osteoblasts grown on the TiO₂ sol-gel surface. Alizarin red-S staining showed higher amount of calcium deposition from osteoblasts cultured on TiO₂ surface than those on titanium discs at day 20. In conclusion, TiO₂ sol-gel coated-titanium could enhance osteoblasts differentiation and promote mineralization, indicating its potential in improving osseointegration for clinical application.