Table Of ContentSPRINGER BRIEFS IN
APPLIED SCIENCES AND TECHNOLOGY
Jürgen Engel
A Critical Survey of
Biomineralization
Control,
Mechanisms,
Functions and
Material Properties
123
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J rgen Engel
A Critical Survey
of Biomineralization
Control, Mechanisms, Functions and Material
Properties
123
JürgenEngel
Department ofBiophysical Chemistry
Biozentrum University of Basel
Basel
Switzerland
ISSN 2191-530X ISSN 2191-5318 (electronic)
SpringerBriefs inApplied SciencesandTechnology
ISBN978-3-319-47710-7 ISBN978-3-319-47711-4 (eBook)
DOI 10.1007/978-3-319-47711-4
LibraryofCongressControlNumber:2016954473
©TheAuthor(s)2017
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Acknowledgements
I am grateful to Prof. Dr. Josephine Adams, University of Bristol, UK, for critical
reading of this manuscript and for many constructive suggestions. Her many cor-
rectionsandcommentsimprovedthetextconsiderably.IalsothankProf.Dr.Hans
PeterBächinger,ShrinersHospitalforChildren,Portland,USA,forcorrectionsand
comments and Dr. Ulrike Engel, Nikon Imaging Centre, University of Heidelberg,
Germany, for many discussions.
v
Contents
1 Introduction... .... .... ..... .... .... .... .... .... ..... .... 1
1.1 What Is Biomineralization?.... .... .... .... .... ..... .... 1
1.2 Discovery and History ... .... .... .... .... .... ..... .... 1
1.3 Linkage with the Extracellular Matrix.... .... .... ..... .... 3
1.4 Why This Book? .. ..... .... .... .... .... .... ..... .... 4
References. .... .... .... ..... .... .... .... .... .... ..... .... 4
2 Chemistry and Minerals. ..... .... .... .... .... .... ..... .... 5
2.1 Biominerals... .... ..... .... .... .... .... .... ..... .... 5
2.2 How to Detect Biomineralization? .. .... .... .... ..... .... 6
Reference . .... .... .... ..... .... .... .... .... .... ..... .... 6
3 Biominerals and Their Function in Different Organisms..... .... 7
3.1 Calcium Carbonate Biominerals .... .... .... .... ..... .... 7
3.2 Silica Biominerals and Silia Biomineralization. .... ..... .... 9
3.3 Iron Oxide Biominerals .. .... .... .... .... .... ..... .... 10
References. .... .... .... ..... .... .... .... .... .... ..... .... 11
4 Different Types of Molecular Control of Biomineralization... .... 13
4.1 Genetic Control ... ..... .... .... .... .... .... ..... .... 13
4.2 Transport Processes in Biomineralization . .... .... ..... .... 14
4.3 The Central Process: Mineral Formation.. .... .... ..... .... 14
Reference . .... .... .... ..... .... .... .... .... .... ..... .... 15
5 Enamel is the Hardest Biomaterial Known... .... .... ..... .... 17
5.1 Formation of Enamel by Vectorial Secretion
from Ameloblasts.. ..... .... .... .... .... .... ..... .... 17
5.2 Biomineralization Is a Replacement of Proteins
by Mineral ... .... ..... .... .... .... .... .... ..... .... 21
5.3 Gene Deletions and Pathological States .. .... .... ..... .... 23
5.4 Open Questions and Speculations... .... .... .... ..... .... 23
References. .... .... .... ..... .... .... .... .... .... ..... .... 27
vii
viii Contents
6 Formation of Mollusk Shells... .... .... .... .... .... ..... .... 29
6.1 Morphology and Structures.... .... .... .... .... ..... .... 29
6.2 Role of Secretion and Organic Matrix: Many Data
and Many Questions..... .... .... .... .... .... ..... .... 32
6.3 Little Genetic Overlap Between Shell Proteins. .... ..... .... 37
References. .... .... .... ..... .... .... .... .... .... ..... .... 40
7 The Glasshouse of Diatoms.... .... .... .... .... .... ..... .... 41
7.1 Formation of the Siliceous Cell Wall During Cell Division .... 43
7.2 Si(OH) Uptake by Silicic Acid Transporters.. .... ..... .... 44
4
7.3 Does a Matrix of Extracellular Proteins Model
the Cell Wall?. .... ..... .... .... .... .... .... ..... .... 45
7.4 Exocytosis, Secretion, and the Cytoskeleton May
Determine Cell Wall Shape ... .... .... .... .... ..... .... 47
References. .... .... .... ..... .... .... .... .... .... ..... .... 48
8 In Vitro Studies of Mineral–Protein Interactions .. .... ..... .... 51
8.1 Solid-State NMR .. ..... .... .... .... .... .... ..... .... 51
8.2 Comparison of Biogenic and Solvent-Grown Crystals .... .... 53
References. .... .... .... ..... .... .... .... .... .... ..... .... 53
9 What Can We Learn from Biology for Material Science?.... .... 55
9.1 Materials by Biological Methods ... .... .... .... ..... .... 56
9.2 Materials by Bioinspired Processes.. .... .... .... ..... .... 56
References. .... .... .... ..... .... .... .... .... .... ..... .... 57
10 Biomineralization Processes for Future Research.. .... ..... .... 59
10.1 Life with Compass: Magnetotactic Bacteria ... .... ..... .... 59
10.2 The Largest Biosilica Structure on Earth: The Deep
Sea Glass Sponge.. ..... .... .... .... .... .... ..... .... 60
References. .... .... .... ..... .... .... .... .... .... ..... .... 61
11 Outlook .. .... .... .... ..... .... .... .... .... .... ..... .... 63
References. .... .... .... ..... .... .... .... .... .... ..... .... 64
Chapter 1
Introduction
1.1 What Is Biomineralization?
Some600millionyearsago,biologicalevolutionalteredthegenesofmollusksina
way that enabled them to incorporate calcium carbonate in the form of its mineral
calcite. The shells of the mollusks provided an effective protection of the delicate
softbodyoftheorganism.Themergingoforganicandinorganiccompoundswasa
big achievement in evolution. Today, mineral incorporation is observed in many,
but not all, living organisms. About 40 different inorganic materials and many
formsofmineralsareused.Themineralsareusuallyinamicrocrystallineformbut
may also be amorphous or in a glass-like state. Functions of mineralizations are
manifold, but usually an improvement of mechanical strength is observed. Unique
mechanical properties were achieved, and this attracts the interest of workers in
materials science. Over geological timescales, whole mountains have been formed
by the deposition of biologically formed minerals.
Thechemical natureofbiominerals,thesites ofdeposition,thetype ofcrystals,
and the patterns of deposition are all genetically controlled by the organism.
Processeswhichlackthiscontrol,suchasossification,donotfallwithinthefieldof
biomineralization.
1.2 Discovery and History
The term biomineralization was coined by Heinz Löwenstam who discovered and
studied mineralized tissues in a wide range of animals from different phyla.
Löwenstam (often called Lowenstam in English texts) was born in Germany in
1912anddiedinCaliforniain1993.Hestudiedbiology,crystallography,geology,
and paleontology in Munich. As a Jew, he was not allowed to finish his Ph.D. at
this university under the Nazi rules and emigrated to the USA in 1936. He started
©TheAuthor(s)2017 1
J.Engel,ACriticalSurveyofBiomineralization,
SpringerBriefsinAppliedSciencesandTechnology,
DOI10.1007/978-3-319-47711-4_1
2 1 Introduction
his field studies in Israel and continued in Chicago. Later he was appointed full
professor at Caltech, where he developed isotope techniques together with
Harold C. Urey. He applied very many different techniques combined with a deep
interest in biological evolution and mechanisms. Long interviews with Heinz
Löwenstam were published in the Archives of the California Institute of
Technology in 1988 [1]. These are still accessible and provide a highly interesting
biography with deep insights in history of science (Fig. 1.1).
I met Heinz Löwenstein in 1963, when I was a postdoctoral fellow at the
Weizmann Institute of Science. I learned from him about snails with mineralized
teeth and other strange topics. These were completely new to me at this time.
Löwenstam impressed me as a scientist and person. Stephen Weiner, a former
student of Löwenstam, is at present director of the Department of Crystallography
attheWeizmannInstitute.In1989,Löwenstam andWeinerpublishedabook“On
Biomineralization” [2]. This book and early reviews [3–6] opened a new field of
biology.
It was shown that mineralization occurs in very many different organisms,
rangingfrombacteria,algae,mollusks,andcoralstoplantsandmammalstomention
a few examples. In the words of evolutionary biologists, biomineralization devel-
opedinallphyla.Manydifferentinorganiccompoundsareinvolved,andtheseoccur
intheformofvariousminerals.Biomineralsusuallydifferfromthemineralsfound
inthe inorganic environmentand from thethermodynamically most stable forms.
My first touch with biomineralization happened by meeting Heinz Löwenstam.
At this time and in the following 40 years, I was working on the structure and
function of collagens and other proteins of the connective tissue (skin, cartilage,
blood vessels, and others), all of mammalian origin. Typical constituents of con-
nective tissues are very large multifunctional proteins, which are located in the
extracellularmatrix(ECM).ManyoftheECMproteinsareintimatelyconnectedto
minerals in calcified tissues such as bone or teeth. The focus of the work of my
research group was on the side of the proteins, but I maintained an interest how
these proteins may catalyze and control mineralization. I was fascinated by the
Fig.1.1 HeinzA.
Löwenstaminhislaboratory
attheCaliforniaInstituteof
Technology,Pasadena,USA,
from[1]
