Microspheres as building blocks for hydroxyapatite/polylactide biodegradable composites

A new generation of organic/inorganic composites is offering a promising approach for creating biocompatible and biodegradable materials with mechanical properties that match that of human bone better than traditional metallic implants. Here, we report a novel technique whereby hydroxyapatite powder is encapsulated in polylactide-based microspheres, processed by an emulsion-solvent evaporation method, and then used as the building blocks to produce dense, microstructurally-uniform composites through a hot pressing route. The mechanical properties of these composites––both ab initio and after in vitro degradation in a simulated environment- were subsequently characterized. Although despite in vitro degradation remains an issue, the Young’s modulus, bending strength and fracture resistance were higher than the corresponding minimum values for human cortical bone. These results suggest that the hot-pressing of hydroxyapatite/polylactide microspheres can be a viable route for the synthesis of load-bearing bone-replacement materials.