The Nucleation Mechanism of Fluorapatite–Collagen Composites: Ion Association and Motif Control by Collagen Proteins

Kawska, Agnieszka; Hochrein, Oliver; Brickmann, Jürgen; Kniep, Rüdiger; Zahn, Dirk

doi:10.1002/ange.200800908

Cited by 34 publications

(38 citation statements)

References 15 publications

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“…Insights regarding this interaction have come from simulations in which HAP served as the mineral prototype (24,25). The results suggest collagen peptides can induce solvated ions to form an apatite-like structure aligned along the collagen axis and that terminal carboxyl groups and amine groups exhibit stronger affinity to HAP (100) than to HAP (001).…”

Section: Significancementioning

confidence: 99%

Energetic basis for the molecular-scale organization of bone

Tao

Battle

Pan

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The remarkable properties of bone derive from a highly organized arrangement of coaligned nanometer-scale apatite platelets within a fibrillar collagen matrix. The origin of this arrangement is poorly understood and the crystal structures of hydroxyapatite (HAP) and the nonmineralized collagen fibrils alone do not provide an explanation. Moreover, little is known about collagen-apatite interaction energies, which should strongly influence both the molecular-scale organization and the resulting mechanical properties of the composite. We investigated collagen-mineral interactions by combining dynamic force spectroscopy (DFS) measurements of binding energies with molecular dynamics (MD) simulations of binding and atomic force microscopy (AFM) observations of collagen adsorption on single crystals of calcium phosphate for four mineral phases of potential importance in bone formation. In all cases, we observe a strong preferential orientation of collagen binding, but comparison between the observed orientations and transmission electron microscopy (TEM) analyses of native tissues shows that only calcium-deficient apatite (CDAP) provides an interface with collagen that is consistent with both. MD simulations predict preferred collagen orientations that agree with observations, and results from both MD and DFS reveal large values for the binding energy due to multiple binding sites. These findings reconcile apparent contradictions inherent in a hydroxyapatite or carbonated apatite (CAP) model of bone mineral and provide an energetic rationale for the molecular-scale organization of bone.biomineralization | bone | protein-mineral interface | dynamic force spectroscopy B one is a natural protein-mineral composite consisting of nonstoichiometric nanometer-scale carbonated apatite crystallites inside a fibrillar protein matrix. The matrix is mainly composed of type I collagen and is organized on multiple length scales (1, 2). At the shortest scale, three polypeptide chains form a triple helix referred to as a tropocollagen molecule that is ∼300 nm in length and 1.5 nm in diameter. These helices are arranged in a quasi-hexagonal bundle in which they overlap and intertwine to form microfibrils containing "hole zones," where there is a gap between the N termini of one helix and the C termini of another (3-5). These microfibrils are further bundled both laterally and longitudinally to form native collagen (3, 4).Within this highly organized scaffold, apatite crystallites form nanometer-scale platelets (6-9) with their [001] axes preferentially aligned parallel to the fibril axis (10-15) and the platelet faces defined by {100} crystal planes (16). Recent in vitro investigations of hydroxyapatite (HAP) formation within collagen fibrils revealed a multistage process in which amorphous calcium phosphate (ACP) first infiltrated through the hole zones and then converted into HAP platelets with initial mineral deposition occurring near the hole zones (11, 13). In vitro transmission electron microscopy (TEM) and atomic force microscop...

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Section: Significancementioning

confidence: 99%

Energetic basis for the molecular-scale organization of bone

Tao

Battle

Pan

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Moreover, the interplay of experimental characterization and atomistic simulation provided a very detailed picture of the biomimetic composite, [9,10] and recently led to the creation of a nanometer-sized simulation model mimicking an apatite-collagen composite at the atomic level. [11] For the present study, this model was further extended to encompass a hexagonal pattern of collagen molecules (approximated by (Hyp-Pro-Gly) n , see also references [9,10]) embedded into 20 20 10 unit cells of apatite. [12] Periodic boundary conditions are applied to mimic a bulk material.…”

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confidence: 99%

A Molecular Rationale of Shock Absorption and Self‐Healing in a Biomimetic Apatite–Collagen Composite under Mechanical Load

Zahn

2010

Angew Chem Int Ed

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“…Mitte und rechts: Nukleation und Wachstum von Apatit-Motiven, begünstigt durch die Tripelhelix des Kollagens. [86] Keimbildung und Kristallwachstum Angewandte Chemie zur Aggregation und der Morphologie von Nanokristallen zum Teil bereits mit den gängigen Simulationsmethoden studiert werden.…”

Section: Simulationen Zur Stabilität Von Nanokristallen Und Deren Phaunclassified

Atomistisches Verständnis der Keimbildung und des Kristallwachstums durch molekulare Simulationen

Anwar

Zahn

2011

Angewandte Chemie

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Die Modellierung von Keimbildungsprozessen durch molekulare Simulation ermöglicht nicht nur die Berechnung kinetischer und thermodynamischer Eigenschaften, sondern bietet zugleich mechanistische Einblicke auf atomarer Ebene. Die vielfältigen Möglichkeiten, Experimente durch Modellsimulationen zu ergänzen, sind jedoch mit der Überwindung einer Reihe von technischen Schwierigkeiten verbunden. Keimbildungsprozesse sind seltene Ereignisse, die direkten Brute‐Force‐Molekulardynamiksimulationen nur in Ausnahmefällen zugänglich sind. Erst durch Fortschritte bei der Überbrückung von Zeit‐ und Längenskalen konnten kürzlich entwickelte Ansätze auch solche Simulationen ermöglichen, die lange Zeit als undurchführbar galten. Dabei können einerseits generische Modelle zur Erarbeitung eines allgemeinen Verständnisses genutzt werden. Zum anderen sind aber auch detaillierte Einblicke in realitätsnahe Systeme möglich, sofern die Kristallbildungsprozesse in handhabbare Module unterteilt werden. So können die Assoziation einzelner Ionen in der Lösung, die Bildung von geordneten Motiven, Reifungsreaktionen, Keimbildung und postkritisches Wachstum von Nanokristallen auf molekularer Ebene untersucht werden. Durch die Analyse des Wechselspiels mit additiven Molekülen lassen sich zudem Einblicke in funktionalisierte Nanopartikel und Kompositmaterialien gewinnen.

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The Nucleation Mechanism of Fluorapatite–Collagen Composites: Ion Association and Motif Control by Collagen Proteins

Cited by 34 publications

References 15 publications

Energetic basis for the molecular-scale organization of bone

Energetic basis for the molecular-scale organization of bone

A Molecular Rationale of Shock Absorption and Self‐Healing in a Biomimetic Apatite–Collagen Composite under Mechanical Load

Atomistisches Verständnis der Keimbildung und des Kristallwachstums durch molekulare Simulationen

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