Abstract

Currently a basic tenet in biomineralization is that biominerals grow by accretion of amorphous particles, which are later transformed into the corresponding mineral phase. The globular nanostructure of most biominerals is taken as evidence of this. Nevertheless, little is known as to how the amorphous-to-crystalline transformation takes place. To gain insight into this process, we have made a high-resolution study (by means of transmission electron microscopy and other associated techniques) of immature tablets of nacre of the gastropod Phorcus turbinatus, where the proportion of amorphous calcium carbonate is high. Tablets displayed a characteristic nanoglobular structure, with the nanoglobules consisting of an aragonite core surrounded by amorphous calcium carbonate together with organic macromolecules. The changes in composition from the amorphous to the crystalline phase indicate that there was a higher content of organic molecules within the former phase. Within single tablets, the crystalline cores were largely co-oriented. According to their outlines, the internal transformation front of the tablets took on a complex digitiform shape, with the individual fingers constituting the crystalline cores of nanogranules. We propose that the final nanogranular structure observed is produced during the transformation of ACC into aragonite.

Details

Title
Transformation of ACC into aragonite and the origin of the nanogranular structure of nacre
Author
Macías-Sánchez, Elena 1   VIAFID ORCID Logo  ; Willinger, Marc G 2   VIAFID ORCID Logo  ; Pina, Carlos M 3   VIAFID ORCID Logo  ; Checa, Antonio G 1   VIAFID ORCID Logo 

 Department of Stratigraphy and Palaeontology, University of Granada, Granada, Spain; Andalusian Earth Sciences Institute (IACT), UGR – CSIC, Avd. de las Palmeras 4, Armilla, Granada, Spain 
 Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany 
 Department of Crystallography and Mineralogy, Complutense University of Madrid, Geosciences Institute (IGEO) (UCM-CSIC), Madrid, Spain 
Pages
1-11
Publication year
2017
Publication date
Oct 2017
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
1957850349
Copyright
© 2017. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.