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

Abstract

Apatite for the structure: Nucleation mechanisms of apatite–collagen composites at the atomistic level of detail have been investigated. Peculiar motifs of the apatite crystal structure were identified in which formation is promoted by ion association to the biomolecule. Apart from acting as a nucleation seed for ionic ordering, collagen triple helices (see picture; red bands) also induce orientation control in these motifs.

A Novel Water‐Soluble Hexanuclear Bismuth Oxido Cluster – Synthesis, Structure and Complexation with Polyacrylate

“…[30] By employing the Kawska-Zahn approach to model crystal aggregation, the association of polyacrylate (Sokalan ® PA15) and sodium ions to [Bi 6 O 4 (OH) 4 ] 6+ was studied in aqueous solution. [31] The association of a single polyacrylate ion may already imply considerable structural changes in the [Bi 6 O 4 -(OH) 4 ] 6+ ion. In two out of three simulation runs (taken as a rough estimate from ten independent runs), the cluster was degenerated from an octahedral motif to a tetrahedral motif (Figure 8).…”

“…By using a docking/relaxation procedure, which is described in detail in ref., [31] the association of up to three polyacrylate ions and a sufficiently large number of Na + ions to allow charge neutrality was investigated in aqueous solution. In the overall system, the solutes are embedded in more than 4000 water molecules, placed in a periodic simulation cell of approximate dimensions of 5 nm ϫ 5 nmϫ 5 nm.…”

Embryonic States of Fluorapatite–Gelatine Nanocomposites and Their Intrinsic Electric‐Field‐Driven Morphogenesis: The Missing Link on the Way from Atomistic Simulations to Pattern Formation on the Mesoscale

“…[3][4][5][6][7][8][9][10][11][12][13][14] This finding is consistent with previous suggestions that in the early stages of morphogenesis the protein macromolecules are less mineralized. [15] 2.2. TEM Results…”

“…2) and is clearly controlled by the collagen triple-helix. [15] Thus, it was speculated that the shape development of the nanocomposite may start from this kind of pre-embryonic state.…”

“…Although the apatite-like motifs are initially and preferably incorporated into the triple-helix, later stages of aggregate growth also exhibit Ca 3 F motif formation lateral to the biomolecule. Strikingly, incorporation into the collagen triple-helix induces the orientation of the triangle motifs with the triangle plane more or less perpendicular to the long axis of the macromolecule [15].…”