Intercalation of Sea Urchin Proteins in Calcite: Study of a Crystalline Composite Material

• DOI: 10.1126/science.250.4981.664
• Publication Date: 2006-10-05T22:10:14Z
• Authors: Amir Berman; Lia Addadi; Åke Kvick; Leslie Leiserowitz; Mitch Nelson; Stephen Weiner
• Keywords: Cleavage (geology); Crystal (programming language)

Sea urchin skeletal elements are composed of single crystals calcite. Unlike their synthetic counterparts, these do not have well-developed cleavage and consequently much more resistant to fracture. This phenomenon is due in part the presence acidic glycoproteins occluded within crystals. By means x-ray diffraction with synchrotron radiation, it shown that protein calcite only slightly decreases coherence length but significantly increases angular spread perfect domains In biogenic calcite, 1/3 1/4 as 20 50 times wide. It proposed macromolecules concentrated at mosaic boundaries oblique deavage planes responsible for change fracture properties. These results may be important material sciences, because unusual nature this material, namely, a composite based on controlled intercalation inside single-crystal lattices.