Biodegradable ceramic matrix composites made from nanocrystalline hydroxyapatite and silk fibers via crymilling and uniaxial pressing

Abstract The treatment of severe bone loss and resultant large bone gaps is a challenge due to the need to stimulate bone growth using a biomaterial that biodegrades slowly and has mechanical properties similar to the surrounding bone. This work proposes a novel biodegradable nanocomposite to address these needs. The first step of the technology is to prepare composite powders consisting of 5 wt% or 15 wt% silk fibers and nanocrystalline hydroxyapatite. Both are biodegradable materials. The composite powders are prepared using cryomilling. The second step is uniaxial pressing of the powders at a pressure up to 1 GPa and a temperature of 80 °C. This leads to a homogenous and dense ceramic matrix composite with good adhesion between the nano-hydroxyapatite and silk fibers. The nano-hydroxyapatite retains its nanocrystalline form. The compressive strength is 275 MPa and the bending strength is 160 MPa, which are comparable to the strength of cortical bone.