Uniform Hexagonal Plates of Vaterite CaCO3 Mesocrystals Formed by Biomimetic Mineralization

• Published in: Advanced functional materials 2006-05, Vol.16 (7), p.903-908
• Main Authors: Xu, A.-W., Antonietti, M., Cölfen, H., Fang, Y.-P.
• Format: Article
• Language: English
• Subjects: Biomimetics; Biomineralization; Calcium carbonate; Calcium carbonate, vaterite; Crystal growth; vaterite
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200500716

Vaterite mesocrystals with hexagonal morphology and uniform size have been successfully synthesized in the presence of a N‐trimethylammonium derivative of hydroxyethyl cellulose via aggregation‐mediated crystallization using a simple gas‐diffusion method. The uniform hexagonal plates display sharp facets and edges, even though they are formed by the aggregation of nanocrystals. The results demonstrate that each vaterite plate can be explained as consisting of aggregates of nanoparticles that share the same three‐dimensional orientation. A mechanism for the formation of hexagonal vaterite mesocrystals made of primary nanoparticles and hexagonal units is also presented. An understanding of the mesoscale transformation process will be helpful in controlling the aggregation‐driven formation of complex higher‐order structured materials and will provide new insights into biomineralization mechanisms. For example, the spines of sea urchins can be discussed within the framework of the mesocrystal concept. This study could provide an additional tool for designing advanced materials and could be used for the synthesis of more complex crystalline three‐dimensional structures. Hexagonal plates of vaterite CaCO3 mesocrystals (see figure) with a narrow size distribution are grown via aggregation‐mediated pathways in the presence of an N‐trimethylammonium derivative of hydroxyethyl cellulose. The mesoscale transformation involving cooperative reorganization of coupled inorganic and organic components could provide new insights into biomineralization mechanisms.