The optimized preparation of HA/L-TiO₂/D-TiO₂ composite coating on porous titanium and its effect on the behavior...

Various surface bioactivation technology has been confirmed to improve the osteogenic ability of porous titanium (pTi) implants effectively. In this study, a three-layered composite coating, i.e. outer layer of hydroxyapatite (HA), middle layer of loose titanium dioxide (L-TiO₂) and inner layer of dense TiO₂ (D-TiO₂), was fabricated on pTi by a combined processing procedure of pickling, alkali heat (AH), anodic oxidation (AO), electrochemical deposition (ED) and hydrothermal treatment (HT). After soaking in simulated body fluid for 48 h, the surface of the AHAOEDHT-treated pTi was completely covered by a homogeneous apatite layer. Using MC3T3-E1 pro-osteoblasts as cell model, the cell culture revealed that both the pTi without surface treatment and the AHAOEDHT sample could support the attachment, growth and proliferation of the cells. Compared to the pTi sample, the AHAOEDHT one induced higher expressions of osteogenesis-related genes in the cells, including alkaline phosphatase, Type I collagen, osteopontin, osteoclast inhibitor, osteocalcin and zinc finger structure transcription factor. As thus, besides the good corrosion resistance, the HA/L-TiO₂/D-TiO₂-coated pTi had good osteogenic activity, showing good potential in practical application for bone defect repair.