Journal Article

PreJuSER-7

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Nucleation and Growth of CaCO3 Mediated by the Egg-White Protein Ovalbumin: A Time-Resolved in-situ Study Using Small-Angle Neutron Scattering

Pipich, V.FZJ* ; Balz, M. ; Wolf, S. E. ; Tremel, W. ; Schwahn, D.FZJ*

2008
American Chemical Society Washington, DC

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Please use a persistent id in citations: doi:10.1021/ja801798h

Abstract: Mineralization of calcium carbonate in aqueous solutions starting from its initiation was studied by time-resolved small-angle neutron scattering (SANS). SANS revealed that homogeneous crystallization of CaCO 3 involves an initial formation of thin plate-shaped nuclei which subsequently reassemble to 3-dimensional particles, first of fractal and finally of compact structure. The presence of the egg-white protein ovalbumin leads to a different progression of mineralization through several stages; the first step represents amorphous CaCO 3, whereas the other phases are crystalline. The formation and dissolution of the amorphous phase is accompanied by Ca (2+)-mediated unfolding and cross-linking of about 50 protein monomers showing the characteristic scattering of linear chains with a large statistical segment length. The protein complexes act as nucleation centers for the amorphous phase because of their enrichment by Ca (2+) ions. SANS revealed the sequential formation of CaCO 3 starting from the amorphous phase and the subsequent formation of the crystalline polymorphs vaterite and aragonite. This formation from less dense to more dense polymorphs follows the Ostwald-Volmer rule.

Keyword(s): Calcium Carbonate: chemistry (MeSH) ; Calcium Chloride: chemistry (MeSH) ; Crystallization (MeSH) ; Neutron Diffraction (MeSH) ; Ovalbumin: chemistry (MeSH) ; Protein Conformation (MeSH) ; Protein Folding (MeSH) ; Scattering, Small Angle (MeSH) ; Water: chemistry (MeSH) ; Calcium Chloride ; Calcium Carbonate ; Water ; Ovalbumin ; J

Note: Record converted from VDB: 12.11.2012

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Contributing Institute(s):

1. Neutronenstreuung (IFF-5)
2. Streumethoden (IFF-4)
3. JCNS (Jülich Centre for Neutron Science JCNS (JCNS) ; JCNS)

Research Program(s):

1. Kondensierte Materie (P54)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)

Appears in the scientific report 2008

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