Biomimetic synthesis of bone-like nanocomposites using the self-organization mechanism of hydroxyapatite and collagen

To fabricate an artificial bone material having bone-like nanostructure and chemical composition, a composite composed of hydroxyapatite (HAp) and collagen was synthesized under a biomimetic condition through the self-organization mechanism between HAp and collagen. The hydroxyapatite/collagen (HAp/Col) composite prepared demonstrated bone-like orientation that the c-axes of HAp nanocrystals were regularly aligned along collagen fibrils. Considering crystallography, driving force of the self-organization of HAp and collagen was assumed to be an interaction between their surfaces, i.e., Ca 2+ ions on the HAp crystals and dissociated carboxyl residues on the collagen molecules. Biocompatibility of the HAp/Col composite was similar to or better than that of HAp ceramics that are known to have an excellent biocompatibility. Bone tissue reactions of the composite demonstrated osteoclastic resorption of the composite followed by new bone formation by osteoblasts, which is very similar to the reaction of a transplanted autogenous-bone. From these results, we conclude that the HAp/Col composite can be successfully utilized as an artificial bone material in both the medical and dental fields as an in vivo filler and in vitro tissue regenerator.