Seashells are made of biominerals — inorganic-organic composites with hierarchically organized structures. When seashells or sea urchin spines are broken, the damaged parts are spontaneously repaired in the living organism. Hiroaki Imai and colleagues, Keio University, Japan, have mimicked this process in vitro.

Calcite prisms were partially etched from the surface of a seashell by a diluted acid. Then, crystal growth was performed with a synthetic, acidic polymer in the etched space surrounded by the remaining insoluble, organic framework. After the partial regeneration, the macroscopic morphologies, the mesocrystal structures, and the crystallographic orientation were successfully reproduced on the original prismatic layer.

These results suggest that inorganic–organic composites based on mesocrystals are repaired through the oriented growth of nanocrystals controlled by organic molecules, which could be applied to other materials.

Image: (c) Wiley-VCH

• In Vitro Repair of a Biomineral with a Mesocrystal Structure
  M. Kijima, Y. Oaki, H. Imai,
  Chem. Eur. J. 2011.
  DOI: 10.1002/chem.201003203