The Fine Structure of Bone

Jackson, Sylvia Fitton; Randall, J. T.

doi:10.1038/178798a0

Cited by 22 publications

(11 citation statements)

References 3 publications

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“…15,16 The mechanism by which collagen directs the orientation of these intrafibrillar HAp crystals is also a topic of debate. 15,[17][18][19] HAp forms within specific gap regions inside the collagen fibrils (also called the hole zone) containing rectangular (2D) channels, 1,12,13,20 that have long been thought to both induce nucleation 9,[21][22][23] and provide an organized organic matrix that guides epitaxial growth (Figure 1). 9,13,18,21 This mechanism has been recently called into question, however, by the demonstration that the HAp platelets in bone are covered by a hydrated amorphous layer that would preclude such molecular recognition.…”

Section: Introductionmentioning

confidence: 99%

Intermolecular Channels Direct Crystal Orientation in Mineralized Collagen

Nudelman

Eren

et al. 2020

Preprint

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The mineralized collagen fibril is the basic building block of bone, commonly pictured as a parallel array of ultrathin carbonated hydroxyapatite (HAp) platelets distributed throughout the collagen. This orientation is often attributed to an epitaxial relationship between the HAp and collagen molecules inside 2D voids within the fibril. Although recent studies have questioned this model, the structural relationship between the collagen matrix and HAp, and the mechanisms by which collagen directs mineralization remain unclear. Here, we use XRD to reveal that the voids in the collagen are in fact cylindrical pores with diameters of ~2 nm, while electron microscopy shows that the HAp crystals in bone are only uniaxially oriented with respect to the collagen. From in vitro mineralization studies with HAp, CaCO3 and γ-FeOOH we conclude that confinement within these pores, together with the anisotropic growth of HAp, dictates the orientation of HAp crystals within the collagen fibril.

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Section: Introductionmentioning

confidence: 99%

Intermolecular Channels Direct Crystal Orientation in Mineralized Collagen

Nudelman

Eren

et al. 2020

Preprint

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“…Recently, a variety of biomass materials (e.g., pig bone, fish scale, barley straw, and bamboo) have been employed as precursors to synthesize HPCs, due to their versatile microstructures, rich heteroatom elements and sustainable resource. Among them, animal bones that possess a unique three dimensional (3D) ordered microstructure, with apatite minerals being sandwiched among the collagen fibrils, are regarded as the promising precursors for the synthesis of HPCs . The collagen fibrils in animal bones are attractive as the carbon precursors, with nitrogen as dopant, to form N‐doped carbon materials, while the apatite minerals can act as a hard template to control the porous structure, resulting in a 3D hierarchically porous carbon network with rich N‐doping and large SSA.…”

Section: Introductionmentioning

confidence: 99%

Towards High‐Performance Electrocatalysts for Oxygen Reduction: Inducing Atomic‐Level Reconstruction of Fe‐N_x Site for Atomically Dispersed Fe/N‐Doped Hierarchically Porous Carbon

Zhang

Dou

et al. 2018

Chemistry A European J

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A rational and effective strategy for the synthesis of a high-performance non-precious metal electrocatalyst for oxygen reduction reaction (ORR) was developed by inducing reconstruction of Fe-N site on pig-bone-derived nitrogen-doped hierarchically porous carbon. The resultant Fe/N-doped carbon electrocatalyst possessed abundant atomically dispersed non-planar Fe-N ORR active sites, with absolute presence of active D1 (Fe -N ) and D3 (N-Fe -N ) sites, as well as large specific surface area and three-dimensional porous structure with hierarchical micro-/meso-/macro-pore distribution, which increased the utilization of active sites and promoted mass transport of ORR reactants. This resulted in a remarkably superior ORR activity with half-wave potential of 0.87 V (20 mV higher than Pt/C) and kinetic current density of 10.9 mA cm at 0.85 V (2.3-fold of Pt/C) in alkaline electrolyte. This methodology provides a route for atomic-level design of high-performance ORR electrocatalyst.

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“…These findings indicate that at least under the conditions described here, the ability to form needle-shaped crystals was unique to the interaction between calcium phosphates and the three amelogenin fragments employed in the present study. The occurrence of nanoscale needle-shaped and parallel organized crystals is predominantly a feature of vertebrate biominerals such as bone, dentin, and developing enamel (Fitton-Jackson and Randall, 1956; Diekwisch et al, 1995; He and George, 2004), even though invertebrates are entirely capable of promoting needle-shaped calcium carbonate spicules, albeit with relatively thicker diameters (Beniash et al, 1999). Our data also indicated that only the C-terminus augmented polyproline fragment promoted the growth of short, thin, and parallel nanoscale crystals, while both the amelogenin N-terminus and the polyproline region alone appeared to fuse individual crystals into thicker subunits.…”

Section: Discussionmentioning

confidence: 99%

The expanded amelogenin polyproline region preferentially binds to apatite versus carbonate and promotes apatite crystal elongation

Gopinathan

Jin²,

Liu

et al. 2014

Front. Physiol.

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The transition from invertebrate calcium carbonate-based calcite and aragonite exo- and endoskeletons to the calcium phosphate-based vertebrate backbones and jaws composed of microscopic hydroxyapatite crystals is one of the great revolutions in the evolution of terrestrial organisms. To identify potential factors that might have played a role in such a transition, three key domains of the vertebrate tooth enamel protein amelogenin were probed for calcium mineral/protein interactions and their ability to promote calcium phosphate and calcium carbonate crystal growth. Under calcium phosphate crystal growth conditions, only the carboxy-terminus augmented polyproline repeat peptide, but not the N-terminal peptide nor the polyproline repeat peptide alone, promoted the formation of thin and parallel crystallites resembling those of bone and initial enamel. In contrast, under calcium carbonate crystal growth conditions, all three amelogenin-derived polypeptides caused calcium carbonate to form fused crystalline conglomerates. When examined for long-term crystal growth, polyproline repeat peptides of increasing length promoted the growth of shorter calcium carbonate crystals with broader basis, contrary to the positive correlation between polyproline repeat element length and apatite mineralization published earlier. To determine whether the positive correlation between polyproline repeat element length and apatite crystal growth versus the inverse correlation between polyproline repeat length and calcium carbonate crystal growth were related to the binding affinity of the polyproline domain to either apatite or carbonate, a parallel series of calcium carbonate and calcium phosphate/apatite protein binding studies was conducted. These studies demonstrated a remarkable binding affinity between the augmented amelogenin polyproline repeat region and calcium phosphates, and almost no binding to calcium carbonates. In contrast, the amelogenin N-terminus bound to both carbonate and apatite, but preferentially to calcium carbonate. Together, these studies highlight the specific binding affinity of the augmented amelogenin polyproline repeat region to calcium phosphates versus calcium carbonate, and its unique role in the growth of thin apatite crystals as they occur in vertebrate biominerals. Our data suggest that the rise of apatite-based biominerals in vertebrates might have been facilitated by a rapid evolution of specialized polyproline repeat proteins flanked by a charged domain, resulting in apatite crystals with reduced width, increased length, and tailored biomechanical properties.

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The Fine Structure of Bone

Cited by 22 publications

References 3 publications

Intermolecular Channels Direct Crystal Orientation in Mineralized Collagen

Intermolecular Channels Direct Crystal Orientation in Mineralized Collagen

Towards High‐Performance Electrocatalysts for Oxygen Reduction: Inducing Atomic‐Level Reconstruction of Fe‐N_x Site for Atomically Dispersed Fe/N‐Doped Hierarchically Porous Carbon

The expanded amelogenin polyproline region preferentially binds to apatite versus carbonate and promotes apatite crystal elongation

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The Fine Structure of Bone

Cited by 22 publications

References 3 publications

Intermolecular Channels Direct Crystal Orientation in Mineralized Collagen

Intermolecular Channels Direct Crystal Orientation in Mineralized Collagen

Towards High‐Performance Electrocatalysts for Oxygen Reduction: Inducing Atomic‐Level Reconstruction of Fe‐Nx Site for Atomically Dispersed Fe/N‐Doped Hierarchically Porous Carbon

The expanded amelogenin polyproline region preferentially binds to apatite versus carbonate and promotes apatite crystal elongation

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Towards High‐Performance Electrocatalysts for Oxygen Reduction: Inducing Atomic‐Level Reconstruction of Fe‐N_x Site for Atomically Dispersed Fe/N‐Doped Hierarchically Porous Carbon