Dopamine-Induced Mineralization of Calcium Carbonate Vaterite Microspheres

Two biogenic materials from mussels are attracting attention from scientists: calcium carbonate (CaCO3), the most widely studied biomineral that composes the shell, or nacre, of mussels, and dopamine, a small catechol-containing biomimetic molecule of adhesive foot proteins secreted by mussels. We have incorporated these two materials into the biomimetic mineralization process to produce stable vaterite microspheres, which are the most unstable crystalline phase of CaCO3. Spherical vaterite crystals were readily formed within two minutes in the presence of dopamine undergoing polymerization and were preserved for over two months in aqueous solution. The microspheres consisted of nanoparticles smaller than 100 nm and exhibited porous and spherulitic cross sections. The prolonged maintenance of spherical structure is attributed to the affinitive interaction between calcium in the vaterite microspheres and catechols from dopamine retarding the dissolution of vaterite and the growth of calcite crystals. The mussel-inspired inducement of a stable vaterite phase suggests a facile route for the synthesis of complex organic−inorganic hybrid materials utilizing biogenic systems.