Immobilisation and characterisation of the demineralised, fully hydrated organic matrix of nacre – An atomic force microscopy study

Launspach, Malte; Rückmann, Klaudia; Gummich, Meike; Rademaker, Hanna; Doschke, Holger; Radmacher, Manfred; Fritz, Monika

doi:10.1016/j.micron.2012.03.014

Cited by 7 publications

(6 citation statements)

References 32 publications

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“…These fibrous matrices were stained by Calcofluor white (Fig. A,B) is indicative for polysaccharides such as chitin that is a common compound in mollusk shells (Degens et al ., ; Jeuniaux, ; Weiner & Traub, ; Launspach et al ., ). The fibrous matrices could be also stained in the other investigated bivalves shells (Fig.…”

Section: Discussionmentioning

confidence: 97%

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

et al. 2014

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Symbiont-bearing and non-symbiotic marine bivalves were used as model organisms to establish biosignatures for the detection of distinctive symbioses in ancient bivalves. For this purpose, the isotopic composition of lipids (δ13C) and bulk organic shell matrix (δ13C, δ34S, δ15N) from shells of several thiotrophic, phototrophic, or non-symbiotic bivalves were compared (phototrophic: Fragum fragum, Fragum unedo, Tridacna maxima; thiotrophic: Codakia tigerina, Fimbria fimbriata, Anodontia sp.; non-symbiotic: Tapes dorsatus, Vasticardium vertebratum, Scutarcopagia sp.). ∆13C values of bulk organic shell matrices, most likely representing mainly original shell protein/chitin biomass, were depleted in thio- and phototrophic bivalves compared to non-symbiotic bivalves. As the bulk organic shell matrix also showed a major depletion of δ15N (down to -2.2 ‰) for thiotrophic bivalves, combined δ13C and δ15N values are useful to differentiate between thio-, phototrophic, and non-symbiotic lifestyles. However, the use of these isotopic signatures for the study of ancient bivalves is limited by the preservation of the bulk organic shell matrix in fossils. Substantial alteration was clearly shown by detailed microscopic analyses of fossil (late Pleistocene) T. maxima and Trachycardium lacunosum shell, demonstrating a severe loss of quantity and quality of bulk organic shell matrix with time. Likewise, the composition and δ13C-values of lipids from empty shells indicated that a large part of these compounds derived from prokaryotic decomposers. The use of lipids from ancient shells for the reconstruction of the bivalve's life style therefore appears to be restricted.

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Section: Discussionmentioning

confidence: 97%

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

et al. 2014

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“…Nacre is a textbook example showing how evolation can lead to high‐performance materials by blending intrinsically weak constituents, CaCO 3 (aragonite) and collagen‐related biopolymers, in a composite. It shows a unique integration of remarkable tensile strength toughness, and electrical conductivity which supplies a strategy for constructing integrated materials.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance TiO₂ Nanoparticle/DOPA‐Polymer Composites

Liaqat

Tahir

Schechtel

et al. 2015

Macromol. Rapid Commun.

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Many natural materials are complex composites whose mechanical properties are often outstanding considering the weak constituents from which they are assembled. Nacre, made of inorganic (CaCO3 ) and organic constituents, is a textbook example because of its strength and toughness, which are related to its hierarchical structure and its well-defined organic-inorganic interface. Emulating the construction principles of nacre using simple inorganic materials and polymers is essential for understanding how chemical composition and structure determine biomaterial functions. A hard multilayered nanocomposite is assembled based on alternating layers of TiO2 nanoparticles and a 3-hydroxy-tyramine (DOPA) substituted polymer (DOPA-polymer), strongly cemented together by chelation through infiltration of the polymer into the TiO2 mesocrystal. With a Young's modulus of 17.5 ± 2.5 GPa and a hardness of 1.1 ± 0.3 GPa the resulting material exhibits high resistance against elastic as well as plastic deformation. A key feature leading to the high strength is the strong adhesion of the DOPA-polymer to the TiO2 nanoparticles.

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“…One of the most commonly found, and hence extensively studied, biominerals is calcium carbonate, CaCO 3 . , Calcium carbonate features a number of polymorphs, with calcite being the most thermodynamically favored polymorph at room temperature and pressure, while aragonite is a less thermodynamically favored polymorph under ambient conditions, but can be stabilized and organized by proteins, − such as in the nacre layer (mother of pearl) of mollusk shells. − The nacre layer has been the subject of numerous studies that have characterized a range of properties, for example, composition, ,, assembly, and mechanical properties. ,− Previous in vitro studies have shown it is possible to control crystallization of the CaCO 3 polymorph via addition of biomolecules, notably those proteins associated with the nacre layer of mollusk shells. − These proteins include the framework class, which are affiliated with the silk-gel/β-chitin coating on the exterior of the nacre tablets, and the intracrystalline class, which are found as intracrystalline inclusions within the mineral tablets themselves (intracrystalline proteins). ,− Thus, to develop new materials strategies that are nacre-based, we will require a better understanding of these two nacre-affiliated protein classes.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium Conformational Ensemble of the Intrinsically Disordered Peptide n16N: Linking Subdomain Structures and Function in Nacre

Brown

Rodger²,

Evans

et al. 2014

Biomacromolecules

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n16 is a framework protein family associated with biogenic mineral stabilization, thought to operate at three key interfaces in nacre: protein/β-chitin, protein/protein, and protein/CaCO3. The N-terminal half of this protein, n16N, is known to be active in conferring this mineral stabilization and organization. While some details relating to the stabilization and organization of the mineral are known, the molecular mechanisms that underpin these processes are not yet established. To provide these molecular-scale details, here we explore current hypotheses regarding the possible subdomain organization of n16N, as related to these three interfaces in nacre, by combining outcomes of Replica Exchange with Solute Tempering molecular dynamics simulations with NMR experiments, to investigate the conformational ensemble of n16N in solution. We verify that n16N lacks a well-defined secondary structure, both with and without the presence of Ca(2+) ions, as identified from previous experiments. Our data support the presence of three different, functional subdomains within n16N. Our results reveal that tyrosine, chiefly located in the center of the peptide, plays a multifunctional role in stabilizing conformations of n16N, for intrapeptide and possibly interpeptide interactions. Complementary NMR spectroscopy data confirm the participation of tyrosine in this stabilization. The C-terminal half of n16N, lacking in tyrosine and highly charged, shows substantive conformational diversity and is proposed as a likely site for nucleation of calcium carbonate. Finally, dominant structures from our predicted conformational ensemble suggest the presentation of key residues thought to be critical to the selective binding to β-chitin surfaces.

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Immobilisation and characterisation of the demineralised, fully hydrated organic matrix of nacre – An atomic force microscopy study

Cited by 7 publications

References 32 publications

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

High‐Performance TiO₂ Nanoparticle/DOPA‐Polymer Composites

Equilibrium Conformational Ensemble of the Intrinsically Disordered Peptide n16N: Linking Subdomain Structures and Function in Nacre

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Immobilisation and characterisation of the demineralised, fully hydrated organic matrix of nacre – An atomic force microscopy study

Cited by 7 publications

References 32 publications

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

The isotopic biosignatures of photo‐ vs. thiotrophic bivalves: are they preserved in fossil shells?

High‐Performance TiO2 Nanoparticle/DOPA‐Polymer Composites

Equilibrium Conformational Ensemble of the Intrinsically Disordered Peptide n16N: Linking Subdomain Structures and Function in Nacre

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High‐Performance TiO₂ Nanoparticle/DOPA‐Polymer Composites