A Mg/Zn-co-doped composite coating on a titanium surface enhances osteogenic activity through the Wnt/β-catenin pathway

Abstract

Although Ti alloys have good biocompatibility and mechanical properties, they lack bioactivity and cannot integrate with surrounding bone tissue when used as implants; thus, their clinical application is limited. In this study, a Mg/Zn-co-doped micro/nanocomposite coating (TZM) was prepared on a Ti alloy surface by plasma electrolytic oxidation (PEO), and the effect of the coating on the biological behaviour of osteoblasts on its surface was observed in experiments conducted in vitro and in vivo. Based on these findings, the role of the Wnt/β-catenin pathway in the effect of TZM on osteogenic differentiation was studied. The results show that TZM had a porous micro/nanostructure and was uniformly co-doped with Mg and Zn. TZM promoted the adhesion, spreading, proliferation and differentiation of MG-63 cells. In vivo experiments showed that Ti implants with the TZM coating stimulated new bone formation and promoted early implant osseointegration. More importantly, the addition of Wnt3a cells cultured on pure Ti (PT) significantly upregulated the level of β-catenin, and the addition of Dkk1 to cells cultured on the TZM surface significantly inhibited β-catenin activity. In conclusion, the preparation of a Mg/Zn-co-doped micro/nanocomposite coating through PEO is a feasible method for enhancing the osteogenic activity of Ti implants, and the Wnt/β-catenin signalling pathway may be involved in the mechanism by which the coating promotes osteoblast differentiation.