In situ magnesium-doped calcium phosphate microtube-reinforced magnesium-doped hydroxyapatite composites with tunable mechanical properties and biodegradability

Abstract

Hydroxyapatite, commonly employed in bone defect repair, demonstrates limitations in load-bearing applications due to its poor mechanical property and biodegradability. This research introduces an innovative bone substitute material, namely, in situ magnesium-doped calcium phosphate microtube (Mg-CaPMT)-reinforced magnesium-doped hydroxyapatite composites (Mg-CaPMT/Mg-HA) inspired by microtube material with outstanding mechanical property and capillary tube in a plant. The in situ Mg-CaPMT, with a ~7 μm diameter and 400-500nm wall thickness, was formed by pore-forming carbon fiber (CF) and the coating on it. These microtubes are uniformly distributed within Mg-HA matrix. The composites can meet load-bearing bone requirements, demonstrating compressive strength of 167.0±20.7MPa and fracture toughness of 2.04±0.13MPa·m1/2. Notably, it exhibits exceptional permeability and biodegradability, attributed to capillary action by the Mg-CaPMT structure. The adjustable mechanical and biological properties of Mg-CaPMT/Mg-HA, based on microtube dimensions, content, and composition, offer a versatile solution for repairing various bone defects in load-bearing areas.