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Transformation of ACC into aragonite and the origin of the nanogranular structure of nacre

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Macías-Sánchez, Elena and Willinger, Marc G. and Pina Martínez, Carlos Manuel and Checa, Antonio G. (2017) Transformation of ACC into aragonite and the origin of the nanogranular structure of nacre. Scientific reports, 7 (12728). pp. 1-11. ISSN 2045-2322

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Official URL: https://www.nature.com/articles/s41598-017-12673-0



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 amorphousto-crystalline transformation takes place. To gain insight into this process, we have made a highresolution 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.


Item Type:Article
Uncontrolled Keywords:Biomineralization; Aragonite
Subjects:Sciences > Geology > Mineralogy
ID Code:55058
Deposited On:23 Apr 2019 08:56
Last Modified:23 Apr 2019 14:11

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