Nonclassical crystallization in vivo et in vitro (II): Nanogranular features in biomimetic minerals disclose a general colloid-mediated crystal growth mechanism.
Recent research has shown that biominerals and their biomimetics (i) typically form via an amorphous precursor phase, and (ii) commonly display a nanogranular texture. Apparently, these two key features are closely related, underlining the fact that the formation of biominerals and their biomimetics does not necessarily follow classical crystallization routes, and leaves a characteristic nanotextural imprint which may help to disclose their origins and formation mechanisms. Here we present a general overview of the current theories and models of nonclassical crystallization and their applicability for the advance of our current understanding of biomineralization and biomimetic mineralization. We pay particular attention to the link between nonclassical crystallization routes and the resulting nanogranular textures of biomimetic CaCO3mineral structures. After a general introductory section, we present an overview of classical nucleation and crystal growth theories and their limitations. Then, we introduce the Ostwald's step rule as a general framework to explain nonclassical crystallization. Subsequently, we describe nonclassical crystallization routes involving stable prenucleation clusters, dense liquid and solid amorphous precursor phases, as well as current nonclassical crystal growth models. The latter include oriented attachment, mesocrystallization and the new model based on the colloidal growth of crystals via attachment of amorphous nanoparticles. Biomimetic examples of nanostructured CaCO3minerals formed via these nonclassical routes are presented which help us to show that colloid-mediated crystal growth can be regarded as a wide-spread growth mechanism. Implications of these observations for the advance in the current understanding on the formation of biomimetic materials and biominerals are finally outlined.
Dpto. Mineralogía y Petrología, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain. Electronic address: carlosrn@ugr.es.
Carlos
C
Rodríguez-Navarro
Dpto. Mineralogía y Petrología, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain.
Encarnación
E
Ruiz-Agudo
Department of Materials Science and Engineering, Institute of Glass and Ceramics (WW3), Friedrich-Alexander-University Erlangen-Nürnberg, Martensstrasse 5, 91058 Erlangen, Germany.
Joe
J
Harris
Department of Materials Science and Engineering, Institute of Glass and Ceramics (WW3), Friedrich-Alexander-University Erlangen-Nürnberg, Martensstrasse 5, 91058 Erlangen, Germany; Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander University Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058 Erlangen, Germany.
Stephan E
SE
Wolf
D032701:Biomimetics / Q000379:methods; D002119:Calcium Carbonate / Q000378:metabolism; D003102:Colloids; D003460:Crystallization; D008903:Minerals / Q000737:chemistry / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry* / Q000378:metabolism
D003102:Colloids; D008903:Minerals; D002119:Calcium Carbonate
Amorphous precursor; Biomimetics; Calcium carbonate; Dense liquid precursors; Nanogranular; Nanoparticle-mediated crystal growth; Nonclassical crystallization; PILP