Ultra-uniform nanocrystalline hydroxyapatite ceramics via two-step sintering and quenching

The enhancement of the mechanical properties of hydroxyapatite (HA) bioceramics constitutes a significant research focus in the biomedical field. The present study is dedicated to the preparation of ultra-uniform nanocrystalline HA bioceramics and their influence on the mechanical properties and biological performances. First, HA powder with a uniform dispersion was fabricated through a sequential process encompassing low-temperature pre-sintering, ball milling, and gradient centrifugation. Subsequently, the green body underwent the two-step sintering and the quenching process to enhance the density and mechanical strength. The nanoceramics displayed excellent hydrophilicity and increased roughness. The nanoindentation tests revealed that the nanoceramics did not undergo any elastic-plastic deformation, and there was no indentation size effect phenomenon. In vitro biological performances suggested that the nanoceramics have the potential to facilitate osteogenic differentiation of bone marrow mesenchymal stem cells. Therefore, it can be concluded that the construction of ultra-uniform nanocrystalline is an effective approach to improve the mechanical and biological properties of HA bioceramics.