Controlling Mineral Morphologies and Structures in Biological and Synthetic Systems

被引:1167
作者
Meldrum, Fiona C. [1 ]
Coelfen, Helmut [2 ]
机构
[1] Univ Bristol, Sch Chem, Bristol BS8 1TS, Avon, England
[2] Max Planck Inst Colloids & Interfaces, D-14424 Potsdam, Germany
基金
英国工程与自然科学研究理事会;
关键词
D O I
10.1021/cr8002856
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
In this article, we have reviewed and discussed the topic of morphological development and control of biogenic and bioinspired minerals. Given the extent of morphological variation in both biology and synthetic systems, this is necessarily an enormous topic, and as such we have aimed to capture the principal elements of this subject by focusing on CaCO3 and silica. CaCO3 and silica are two of the most abundant biominerals, have been widely studied in biomimetic systems, and serve to illustrate the routes available for controlling the morphologies of crystalline and amorphous materials, respectively. One clear message delivered by our review of mineral morphologies in synthetic systems is that complex morphologies need not be restricted to nature; purely synthetic, inorganic minerals can adopt morphologies that are every bit as remarkable as their natural counterparts. A very good example of this are the "biomorphs" discussed in section 4.2.7. Garcia Ruiz and Hyde, who are at the forefront of this field, have already addressed this question. Entirely inorganic and abiotic biomorphs have been produced that d isplay morphologies almost identical to the supposed cyanobacterial microfossils from the Precambrian Warrawoona chert formation in Western Australia. These are reputed to be the oldest terrestrial microfossils. These findings have certainly also to be considered in the field of "nanobes", which are reported to be dwarf forms of bacteria, 0.05-0.2 μm in size-that is, about one-tenth of the diameter and one-thousandth of the volume of ordinary bacteria. They would, thus, be the smallest form of life on earth, Interestingly, nanobes are found to be enormously abundant in minerals and rocks. The discussion of extraterrestrial magnetite, where the resemblance of these crystals to the magnetosomes found in magnetotactic bacteria is considered indicative of former life on Mars, needs also to consider possible abiotic morphogenesis scenarios of the kind summarized in this review. Given the morphological and structural control of crystals that can be achieved in purely synthetic systems, it could be argued that the existing crystallographic and morphological evidence cannot conclusively support the existence of former life on Mars. A key issue arising from this discussion is that biology has devised ways to control mineral morphologies and structures with almost perfect reproducibility. Many of these "biological" morphologies can be produced synthetically and can be found in geological samples. However, the abiotic samples require a unique microenvironment that is often difficult to characterize and reproduce. This is still one of the major obstacles in the application of bioinspired approaches to mineralization reactions. A large number of potent additives have already been identified and used to control the crystallization and morphology of a wide range of minerals. However, the mechanisms by which these additives operate throughout the entire morphogenesis process are often time-dependent and are extremely difficult to access. Further, biomineralization processes, which form the inspiration for many strategies applied to mineralization in synthetic systems, are also very complex and difficult to study. Many questions remain to be answered on the structural, morphological, and orientational control of biominerals in vivo. Study of mineral formation in both biological and synthetic systems clearly offers a challenging analytical problem, where a multicomponent system varies in time and space over orders of magnitude. Nevertheless, remarkable results have already been achieved. Morphogenesis processes certainly depend on the nature of the mineral - for example, whether it is amorphous, single crystalline, or polycrystalline. The production of complex morphologies from amorphous materials such as silica or ACC appears relatively straight-forward, as these isotropic materials can me molded to any desired shape using templating approaches. A wider range of strategies are available for the morphological control of single-crystal and polycrystalline materials. Templating is again a general strategy and has been successfully applied to both single crystals and polycrystals. While it has been widely applied to polycrystalline materials, where it is clear that small units can be packed to form any selected morphology, templating of single crystals has received less attention. This is partly because this method is restricted by the requirement that the equilibrium size of the crystal under the applied growth conditions must exceed the length scale of the template and partly because it is often assumed that single crystals cannot be produced with complex morphologies by such a simple route. Looking beyond templating approaches, soluble additives are widely used to control crystalline morphologies. In the thermodynamic regime, the action of additives can be understood in terms of face-selective additive adsorption, which is displayed in the final morphology as a consequence of Wulff's rule. The mechanisms operating in the kinetic regime are often quite different. Amorphous or even liquid precursors are frequently found, and the reaction can proceed via several metastable polymorphs, following Ostwald's rule of stages. In this regime, the crystallization pathway often does not follow the classical textbook view of layerwise atom/ion/molecule addition to a critical crystal nucleus but instead proceeds via the self-assembly of nanoparticulate precursor units. Self-assembly mechanisms including "oriented attachment" and "mesocrystal formation", both of which have been identified in synthetic mineralization systems, can be summarized under the term "nonclassical crystallization". These mechanisms display the common feature that they lead to the formation of a single-crystal product by elimination of nanoparticle interfaces through crystallographic fusion. The distinction between single crystals formed by classical crystallization and nonclassical nanoparticle-mediated crystallization should, therefore, be based on the nature of the nucleation event. In the former case, a single nucleation event occurs, while nanoparticle-mediated crystallization is associated with multiple nucleation events. Nonclassical crystallization has also been reported for a number of biominerals and clearly offers a number of advantages over traditional ion-by-ion crystal-growth mechanisms. For example, nanoparticle-based crystallization scenarios where nanoparticles can be synthesized at one location prior to transportation to the mineralization site, avoids high salt concentrations with their associated high osmotic pressures and the transport of large solution volumes for the precipitation of sparingly soluble salts. While the traditional approach is to use biological system as an inspiration for the synthetic, it is clear that the converse can also hold true, and mineralization in synthetic systems can provide insight into possible mechanisms active in biomineralization processes. This is especially important as it is generally far easier to identify mechanisms for controlled synthetic systems than it is for in vivo environments. Current developments undoubtedly demonstrate that it will probably be possible to control the morphologies of all inorganic and many organic crystals forming via ions. This can be achieved using a suite of methods including flexible molecular templates, rigid templates, tailored self-assembly mechanisms, and other strategies discussed in this review. These emerging bioinspired approaches may also provide a starting point for developing alternative pathways, leading to the formation of minerals and crystals with complex morphologies. As an extension of this strategy, there is also a requirement to examine the relationship between the structural type and complexity (shape, size, phase, dimensionality, hierarchy, etc.) of materials and their properties. This is likely to result in novel applications in many areas of materials science and other related fields. Biominerals, with their complex morphologies and properties optimized for their function, also provide a unique inspiration for materials design. Despite being formed under ambient conditions from inorganic minerals with comparatively poor physical properties, nature creates materials whose properties challenge those of many synthetic products. Adopting a similar approach, it should be possible to optimize materials properties by controlling and defining their structures, organization, and morphologies. In this respect, morphosynthesis is an important component in the rapidly developing field of bottom-up synthesis in nanotechnology. As this review shows, although significant work remains to be carried out in this area, many significant mechanisms of morphological and structural control in biomineralization and bioinspired mineralization have already been identified that could be readily applied to the field of synthetic materials. © 2008 American Chemical Society.
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页码:4332 / 4432
页数:101
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共 733 条
[1]   Mollusk shell formation: A source of new concepts for understanding biomineralization processes [J].
Addadi, L ;
Joester, D ;
Nudelman, F ;
Weiner, S .
CHEMISTRY-A EUROPEAN JOURNAL, 2006, 12 (04) :981-987
[2]   INTERACTIONS BETWEEN ACIDIC MACROMOLECULES AND STRUCTURED CRYSTAL-SURFACES - STEREOCHEMISTRY AND BIOMINERALIZATION [J].
ADDADI, L ;
WEINER, S .
MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 1986, 134 (1-4) :305-322
[3]   Taking advantage of disorder: Amorphous calcium carbonate and its roles in biomineralization [J].
Addadi, L ;
Raz, S ;
Weiner, S .
ADVANCED MATERIALS, 2003, 15 (12) :959-970
[4]   A CHEMICAL-MODEL FOR THE COOPERATION OF SULFATES AND CARBOXYLATES IN CALCITE CRYSTAL NUCLEATION - RELEVANCE TO BIOMINERALIZATION [J].
ADDADI, L ;
MORADIAN, J ;
SHAY, E ;
MAROUDAS, NG ;
WEINER, S .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1987, 84 (09) :2732-2736
[5]   INTERACTIONS BETWEEN ACIDIC PROTEINS AND CRYSTALS - STEREOCHEMICAL REQUIREMENTS IN BIOMINERALIZATION [J].
ADDADI, L ;
WEINER, S .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1985, 82 (12) :4110-4114
[6]   CRYSTAL PROTEIN INTERACTIONS STUDIED BY OVERGROWTH OF CALCITE ON BIOGENIC SKELETAL ELEMENTS [J].
AIZENBERG, J ;
ALBECK, S ;
WEINER, S ;
ADDADI, L .
JOURNAL OF CRYSTAL GROWTH, 1994, 142 (1-2) :156-164
[7]   Patterned crystallisation on self-assembled monolayers with integrated regions of disorder [J].
Aizenberg, J .
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 2000, (21) :3963-3968
[8]   Control of macromolecule distribution within synthetic and biogenic single calcite crystals [J].
Aizenberg, J ;
Hanson, J ;
Koetzle, TF ;
Weiner, S ;
Addadi, L .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1997, 119 (05) :881-886
[9]   Crystallization in patterns: A bio-inspired approach [J].
Aizenberg, J .
ADVANCED MATERIALS, 2004, 16 (15) :1295-1302
[10]   MORPHOGENESIS OF CALCITIC SPONGE SPICULES - A ROLE FOR SPECIALIZED PROTEINS INTERACTING WITH GROWING CRYSTALS [J].
AIZENBERG, J ;
HANSON, J ;
ILAN, M ;
LEISEROWITZ, L ;
KOETZLE, TF ;
ADDADI, L ;
WEINER, S .
FASEB JOURNAL, 1995, 9 (02) :262-268