Chemically Pre-treated and Biomimetically Coated Titanium for Medical Applications: the True Structure Revealed by Transmission Electron Microscopy

摘要

Scanning (SEM) and cross-sectional transmission (TEM) electron microscopy analyses have been performed to study the transformations induced on the surface of titanium implants by a sequence of chemical treatments having as goal to induce the nucleation and growth of hydroxy-carbonated apatite (HCA). In the first step, an acid etching forms a rough titanium hydride layer, which remains unchanged after subsequent treatments. In a second step, soaking in a NaOH solution induces the growth of nanobelt tangles of nanocrystallized, monoclinic sodium titanate. In a third step, soaking in a simulated body fluid transforms sodium titanate into calcium and phosphorus titanate, by ion exchange in the monoclinic structure. Then, HCA grows and embodies the tangled structure. The interfaces between the different layers are shown to be strong enough to prevent from interfacial decohesion. The role of the titanate structure in the nucleation of HCA is finally discussed.