Stabilized Amorphous Calcium Carbonate as a Precursor of Microcoating on Calcite.

Taeyoung Jeon,Il Won Kim,Ye-Eun Na,Dongchan Jang

doi:10.3390/ma13173762

Taeyoung Jeon, Il Won Kim + Show 2 more

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https://doi.org/10.3390/ma13173762

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Abstract

Highly controlled biomineralization of calcium carbonate is via non-classical mesocrystallization of amorphous precursors. In the present study, a simple in vitro assay was developed to mimic the biological process, which involved stabilized amorphous calcium carbonate and a single crystal substrate of calcite. The microcoating layer formed on the calcite substrate displayed mesocrystalline characteristics, and the layers near the substrate were strongly influenced by the epitaxy to the substrate. This behavior was preserved even when the morphology of the coating layer was modified with poly(acrylic acid), a model anionic macromolecule. Interestingly, the extent of the epitaxy increased substantially with poly(ethylene imine), which barely affected the crystal morphology. The in vitro assay in the present study will be useful in the investigations of the biomineralization and bioinspired crystallization of calcium carbonate in general.

Highlights

Natural composite materials, such as woods, bones, teeth, and mollusk shells, exhibit superior mechanical properties, originating from their intricately hierarchical structures [1,2]
amorphous calcium carbonate (ACC) formation under the conditions employed in the present study was confirmed using optical microscopy (OM)
The crystallographic orientation of the coating layer exhibited the control originating from the single crystal substrate

Summary

Introduction

Natural composite materials, such as woods, bones, teeth, and mollusk shells, exhibit superior mechanical properties, originating from their intricately hierarchical structures [1,2]. Mollusk shells and tooth enamel possess high amounts of inorganic crystals (>95%) without showing brittle failure behavior [3,4]. Mollusk shells have been extensively studied as a model system of high-performance composites. Their hierarchical structures of nanograin and microplate have been well documented [3,5,6,7]. The structural construction of the major inorganic phase (calcium carbonate) was via minor organic components, and amorphous calcium carbonate (ACC) is an essential precursor during the control process, which transforms into desired polymorphs and morphologies of crystals most likely through mesocrystallization [7,8,9,10,11,12]

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