Microstructure, stability and biocompatibility of hydroxyapatite – titania nanocomposites formed by two step sintering process

Abstract

In the present work, we report the characterization of TiO2-hydroxyapatite (HA) nanocomposites obtained by a two-step sintering (TSS) process of a mixture of HA and titanium hydride (TiH2) powders. The reactions underwent by TiH2 in the presence of HA and hydrogen release, and subsequently, titanium oxidation was examined by thermal analysis. A longer holding time in the second sintering stage enabled obtaining a homogenous TiO2-HA (36% rutile) composite with a thermal expansion coefficient of 11.46 · 10−6 C−1 in the 40–1000 °C range. Unconventional TSS process hinders HA decomposition to detrimental tricalcium phosphate (TCP). Wear rate of ceramics was determined by tribological measurements and the material biocompatibility was evaluated using MTT assay. Overall, cell viability results correlated with morphological observations indicated a good biocompatibility of HA-based composites at all tested concentrations. Incorporation of the TiO2 phase in HA by TSS process was found to be an efficient way to prepare bioceramics with improved performances. Keywords: Hydroxyapatite, Two-step sintering (TSS), Thermal analysis, Biocompatibility