Biomineralization I (eBook)

Preface 9
Contents 11
Crystallization of Calcium Carbonate Beneath Insoluble Monolayers: SuitableModels of Mineral – Matrix Interactions in Biomineralization? 13
1 Introduction 14
2 Crystallochemical Aspects of CaCO3 Biomineralization 16
3 Mollusc Shell Formation 20
4 Crystallization of CaCO3 Beneath Monolayers 28
5 Formation of Tabular Aragonite Crystals via a Non- Epitaxial Growth Mechanism 45
6 Conclusions 46
References 50
Self-Organized Formation of Hierarchical Structures 54
1 Introduction: The Hierarchy of Biominerals 54
2 A Hierarchy of Nonclassical Crystallization 56
3 Self-Organization for Morphogenesis on Crystal Growth 58
4 Self-Organization of Branching Morphologies 60
5 Self-Organization of Novel Morphologies 65
6 Oriented Architectures Consisting of Small Building Blocks 71
7 Conclusions: Self-Organization for Hierarchical Structures 79
References 80
Fluorapatite-Gelatine-Nanocomposites: Self- OrganizedMorphogenesis, Real Structure and Relations to Natural Hard Materials 84
1 Introduction 85
2 Experimental (Double Diffusion and Liesegang Bands) 88
3 Form-Development (Macroscopic Length-Scale) 90
4 Overall Characterization of the Fractal Composite Aggregates 100
5 The Virgin Composite Seed (Fractal Series) 111
6 Ion-Impregnation (Pre-Structuring) of the Gelatine-Gel 118
7 Electrical Fields (Fractal Series) 126
8 The Biomimetic Composite in Relation to Natural Hard Materials 130
9 First Applications 132
10 Conclusion and Prospective 133
References 134
Inorganic-Organic Interfacial Interactions in Hydroxyapatite Mineralization Processes 137
1 Introduction 138
2 Organic Matrix-Mediated Crystallization of HAp 140
3 Atomic Scale {100} Interfacial Structure in HAp 155
4 Concluding Remarks 160
References 161
Detoxification Biominerals 164
1 Hemozoin Biomineralization 165
2 Biomineralization of Cadmium Sulfide 176
3 Noble Metal Biomineralization 183
4 Summary 189
References 191
Author Index Volumes 251–271 195
Subject Index 205

Fluorapatite-Gelatine-Nanocomposites: Self-OrganizedMorphogenesis, Real Structure and Relations to Natural Hard Materials (p. 74-75)

Abstract The biomimetic system fiuorapatite-gelatine (in aqueous solutions) is perfectly suited for the study of biomimetic steps closely related to steps in osteo- and dentinogenesis. Although representing a relatively low level of complexity, the biomimetic system still includes all aspects of complexity, such as metastability, self assembly, self-similarity, fractals, pattern-formation, hierarchy, and others. The present review is focused on the morphogenesis and real structure of fiuorapatite-gelatine-nanocomposites and is structured in a sequence from macroscopic/bulk-properties to mesoscopic and finally microscopic observations, in part also supported by atomistic simulations. The field encompasses a large variety of components reaching from basic science to applications. Keywords Applications · Atomistic simulations · Electrical dipole fields · Fluorapatite · Gelatine · Morphogenesis · Nanocomposites

1 Introduction

The biomimetic system fiuorapatite-gelatine bears strong resemblance to the biosystem hydroxyapatite (HAP)-collagen which plays a decisive role in the human body (vertebrates in general) as functional material in the form of bone [1, 2] and teeth [3, 4]. In the bio-systems, the hierarchical and self-similar organization of nanocomposite structures is of prominent relevance [5–8], with HAP-protein (collagen) nanocomposite structures dominated by a close orientational relationship between the triple-helical collagen molecules (arranged in the form of fibrils) and the HAP nanocrystals which .rst nucleate in the gaps between neighboring protein molecules. In these arrangements, the crystallographic c-axes of theHAP nanocrystals are oriented parallel to the longitudinal direction of the fibrils [9, 10].

As the development of bone and teeth proceeds during processes of high complexity involving metabolisms and cell activities of living system, it was a consistent decision to clearly reduce the level of complexity by restricting the investigations to water-soluble gelatine (denatured collagen) and aqueous solutions of the appropriate ions needed for the formation of apatite. The biomineralization process is then mimicked by a double diffusion system in which the ions migrate into a gelatine gel from opposite reservoirs containing solutions of calcium and phosphate/fiuoride, respectively. The mobility of the protein (gelatine) in the gel thereby eases rearrangements of the protein fibers during processes of self-organization.

1.1 Basic Idea and Conception

The chemical system under consideration raised great hopes as being representative of a materials combination that had been optimized during the processes of evolution, and which would allow us to gain deeper insight into the general principles of biomineralization (the formation of inorganic/organic nanocomposites). This task is a real challenge and has to be tackled on all length scales accessible by various methods of investigation. Therefore, the present review is structured in a sequence from macroscopic/bulk-properties to mesoscopic and finally microscopic observations. We are still far away from a perfect understanding of all the experimental indications obtained so far, but it has already become clear that the first steps in this direction have been taken showing promising future trends. The field encompasses all the components from basic science to applications. With respect to materials properties and applications an increasing interest is clearly reflected by the presently increasing number of publications dealing with apatite-gelatine composites [11–14].