Corrosion resistance and cytocompatibility studies of zinc-doped fluorohydroxyapatite nanocomposite coatings on titanium implant

Abstract

In this study, zinc-doped fluoridated hydroxyapatite (ZnFHA) nano-composite coatings were deposited on the surface of commercially pure titanium (Ti-cp) via electrolytic deposition technique. The phase composition, crystallite size, microstructure, and elemental composition of coated specimens were characterized using different techniques including Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis respectively. The influence of coatings on the corrosion behaviour of the specimens was determined by potentiodynamic polarisation in simulated body fluid. In vitro biocompatibility tests, MTT and alkaline phosphatase (ALP) were also employed to assess the cytocompatibility of ZnFHA coating with osteoblast-like MC3T3-E1 cells. Results demonstrated that zinc and fluoride were successfully incorporated into apatite lattice structure. Co-doping of Zn2+ and F− ions decreased hydroxyapatite unit cell volume and grain sizes. Obtained coatings were totally crack-free and dense, which led to decrease in corrosion current densities of Ti-cp in physiological solutions. In addition, cytocompatibility tests demonstrated a good osteoblast proliferation and spreading on ZnFHA. More importantly, results showed that the Zn/F-doping can promote ALP expression, which is a probable effect of a combination of nanostructured surface effects and ion release (Zn2+ and F−). Overall, the ZnFHA coated Ti-cp possesses favourable corrosion resistance and cytocompatibility for the application as biomedical implant material.