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

摘要

Applying sol gel based coatings to orthopedic metallic implant materials can significantly improve their properties and lifespan in vivo. For this work, niobium (Nb_2O_5) and titanium (TiO_2) 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 Nb_2O_5 at 75 ℃ with 40% weight loss below 400 ℃, and minimal weight loss between 400 and 850 ℃ Regarding TiO_2 an endotherm was present at 92 ℃ with 25% weight loss below 400 ℃, and 4% between 400 and 850 ℃. Phase evolution was determined using High Temperature X-ray Diffraction (HT-XRD) where amorphous-Nb_2O_5 (450 ℃), hexagonal-Nb_2O_5 (525 ℃), orthorhombic-Nb_2O_5 (650 ℃), amorphous-TiO_2 (275 ℃) and tetragonal TiO_2 (500 ℃) 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 Nb_2O_5 (525 ℃) and TiO_2 (500 ℃) 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 TiO_2 (122%) samples when compared to the growing cell population while Nb_2O_5 samples exhibited a range of viability (64-105%), partially dependent on materials atomic structure.