Biogenic calcium carbonate forms the inorganic component of seashells, otoliths, and many marineskeletons, and its formation is directed by an ordered template of macromolecules. Classicalnucleation theory considers crystal formation to occur from a critical nucleus formed by theassembly of ions from solution. Using cryotransmission electron microscopy, we found thattemplate-directed calcium carbonate formation starts with the formation of prenucleation clusters.Their aggregation leads to the nucleation of amorphous nanoparticles in solution. Thesenanoparticles assemble at the template and, after reaching a critical size, develop dynamiccrystalline domains, one of which is selectively stabilized by the template. Our findings haveimplications for template-directed mineral formation in biological as well as in synthetic systems.
Materials and Interface Chemistry
Facility/equipment: Research lab