Investigating the structure and biocompatibility of niobium and titanium oxides as coatings for orthopedic metallic implants

Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb2O5) and titanium (TiO2) oxides were prepared via solution processing in order to determine the effect of atomic arrangement (amorphous/crystalline) on bioactivity. Thermal evaluation on the synthesized materials identified an endotherm for Nb2O5 at 75 degrees C with 40% weight loss below 400 degrees C, and minimal weight loss between 400 and 850 degrees C. Regarding TiO2 an endotherm was present at 92 degrees C with 25% weight loss below 400 degrees C, and 4% between 400 and 850 degrees C. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb2O5 (450 degrees C), hexagonal-Nb2O5 (525 degrees C), orthorhombic-Nb2O5 (650 degrees C), amorphous-TiO2 (275 degrees C) and tetragonal TiO2 (500 degrees C) structures were produced. Simulated body fluid (SBF) testing was conducted over 1,7 and 30 days and resulted in positive chemical and morphological changes for crystalline Nb2O5 (525 degrees C) and TiO2 (500 degrees C) after 30 days of incubation. Rod-like CaP deposits were observed on the surfaces using Scanning Electron Microscopy (FE-SEM) and Grazing Incidence-X-ray Diffraction (GI-XRD) shows that the deposits were X-ray amorphous. Cell viability was higher with the TiO2 (122%) samples when compared to the growing cell population while Nb2O5 samples exhibited a range of viability (64-105%), partially dependent on materials atomic structure. (C) 2015 Elsevier B.V. All rights reserved.