Mussel-inspired transformation of CaCO3 to bone minerals

We report a mussel-inspired route to create carbonated bone hydroxyapatite from CaCO3 vaterite microspheres. When catechol-containing dopamine, a biomimetic small molecule of mussel adhesive proteins, was incorporated during the mineralization of CaCO3, the oxidative polymerization of dopamine stabilized the formation of spherical vaterite, the most unstable phase among CaCO3 crystalline structures. Thus-formed vaterite microspheres were readily transformed to carbonated hydroxyapatite crystals when incubated in a simulated body fluid at human body temperature. We found that dopamine not only stabilized the vaterite phase but also influenced the level of conversion to carbonated hydroxyapatites. Considering that carbonated hydroxyapatites are highly bioresorbable, similar to natural bone and dentin, the synthesis of a mussel-inspired hybrid material showing good in vitro bone bioactivity should present a new prospect for future applications in the treatment of bone defects and bone degenerative diseases.