Bone-like peptide/hydroxyapatite nanocomposites assembled with multi-level hierarchical structures

Inspired by nature's strategy for creating organic/inorganic hybrid composite materials, we developed a simple but powerful method to synthesize bone-like peptide/hydroxyapatite nanocomposites using a mussel-mimetic adhesive, polydopamine. We found that polydopamine was uniformly coated in a graphite-like layered structure on the surface of self-assembled diphenylalanine (Phe-Phe, FF) nanowires and enabled the epitaxial growth of c-axis-oriented hydroxyapatite nanocrystals along the nanowires, which is similar to mineralized collagen nanofibers of natural bone. The mineralized peptide nanowires were further organized in relation to each other and then readily hybridized with osteoblastic cells, resulting in the formation of multi-level hierarchical structures. They were found to be nontoxic and enabled efficient adhesion and proliferation of osteoblastic cells by guiding filopoidal extension.