Structural Characterization of the Transient Amorphous Calcium Carbonate Precursor Phase in Sea Urchin Embryos

Politi, Yael; Levi‐Kalisman, Yael; Raz, Sefi; Wilt, Fred H.; Addadi, Lia; Weiner, Steve; Sagi, Irit

doi:10.1002/adfm.200600134

Cited by 209 publications

(270 citation statements)

References 42 publications

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“…However, it has been suggested that water molecules may be present as part of an initial hydrated ACC phase that subsequently transforms into the anhydrous phase (7,18). Our data are in good agreement with this mechanism, and we suggest that they represent direct observation of the dehydration step for freshly deposited ACC.…”

Section: Resultssupporting

confidence: 87%

“…Our data are in good agreement with this mechanism, and we suggest that they represent direct observation of the dehydration step for freshly deposited ACC. Because this type 2 phase is the most abundant in fresh spicules it is likely to be the same anhydrous ACC phase observed with bulk methods (18,19) and now confirmed to be formed from an earlier transient phase. We note that the probing depth in these experiments is only 3 nm.…”

Section: Resultssupporting

confidence: 60%

“…Thus only the fresh material that is deposited on the spicule surface upon thickening is sampled. A recent EXAFS study showed that the transient ACC phase at this stage has a short-range order that resembles the mature crystalline phase (18), which might be the origin of the prominent peak 2. The type 2 mineral is therefore intermediate between fully disordered, probably hydrated ACC and crystalline calcite with respect to both spicule development stage and crystallinity.…”

Section: Resultsmentioning

confidence: 87%

“…1 shows spectra acquired from a 48-h embryo spicule with a pixel size of 200 nm. At this stage the spicule is at the triradiate stage of development and is composed of 70-90% ACC (18). The spectra were extracted from areas near the tip and along 1 of the spicule radii.…”

Section: Resultsmentioning

confidence: 99%

“…No crystallization front can be detected at the micrometer scale. Extended X-ray absorption fine structure (EXAFS) spectroscopy at the Ca K-edge showed that even at early stages, when the mineral is still predominantly amorphous, it already has a nascent short-range order around the calcium ions similar to that in calcite (18). In contrast to stable biogenic ACC, which contains 1 water molecule per CaCO 3 , the amorphous phase in the spicules is mostly anhydrous when the spicules are extracted at an advanced developmental stage (12,19).…”

mentioning

confidence: 99%

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Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule

Politi

Metzler²,

Abrecht³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

377

420

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Sea urchin larval spicules transform amorphous calcium carbonate (ACC) into calcite single crystals. The mechanism of transformation is enigmatic: the transforming spicule displays both amorphous and crystalline properties, with no defined crystallization front. Here, we use X-ray photoelectron emission spectromicroscopy with probing size of 40–200 nm. We resolve 3 distinct mineral phases: An initial short-lived, presumably hydrated ACC phase, followed by an intermediate transient form of ACC, and finally the biogenic crystalline calcite phase. The amorphous and crystalline phases are juxtaposed, often appearing in adjacent sites at a scale of tens of nanometers. We propose that the amorphous-crystal transformation propagates in a tortuous path through preexisting 40- to 100-nm amorphous units, via a secondary nucleation mechanism.

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Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 60%

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Transformation mechanism of amorphous calcium carbonate into calcite in the sea urchin larval spicule

Politi

Metzler²,

Abrecht³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

377

420

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Biomineralization: Self‐Assembly Processes

Chen

2005

Encyclopedia of Inorganic Chemistry

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This article focuses on biomineralization processing involving nanoparticle self‐assembly. Biomineralization is a process of depositing inorganic or inorganic–organic hybrid materials as complex shapes or as hierarchical structures on various size scales having unique properties. Emerging nonclassical crystallization methods of self‐assembly are summarized, including oriented attachment, mesocrystal growth from amorphous precursors, and polymer particle assembly from polymer‐induced liquid precursors. Recent progress in understanding biomineralization in nature and biomimetic mineralization via nanoparticle self‐assembly directed by organic molecules is summarized. Crystallization in organisms commonly involves biopolymer‐induced nucleation and growth, self‐assembly of nanobuilding blocks, and organization of amorphous precursors. A better understanding of biomineralization in organisms and self‐assembly process, in general, will lead to the rational design and synthesis of functional materials having well‐defined hierarchical structures, controlled length scales, and desired properties under environment‐friendly conditions.

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