title: An NMR Study of Biomimetic Fluorapatite - Gelatine Mesocrystals.
abstract: The mesocrystal system fluoroapatite-gelatine grown by double-diffusion is characterized by hierarchical composite structure on a mesoscale. In the present work we apply solid state NMR to characterize its structure on the molecular level and provide a link between the structural organisation on the mesoscale and atomistic computer simulations. Thus, we find that the individual nanocrystals are composed of crystalline fluorapatite domains covered by a thin boundary apatite-like layer. The latter is in contact with an amorphous layer, which fills the interparticle space. The amorphous layer is comprised of the organic matrix impregnated by isolated phosphate groups, Ca3F motifs and water molecules. Our NMR data provide clear evidence for the existence of precursor complexes in the gelatine phase, which were not involved in the formation of apatite crystals, proving hence theoretical predictions on the structural pre-treatment of gelatine by ion impregnation. The interfacial interactions, which may be described as the glue holding the composite materials together, comprise hydrogen bond interactions with the apatite PO4(3-) groups. The reported results are in a good agreement with molecular dynamics simulations, which address the mechanisms of a growth control by collagen fibers, and with experimental observations of an amorphous cover layer in biominerals.
authors.affiliation: Institut für Experimentelle Physik, TU Bergakademie Freiberg, Leipziger Straße 23, 09596 Freiberg, Germany.|Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Vyalikh
authors.affiliation: Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Simon
authors.affiliation: University of Konstanz, Physical Chemistry, POB 714, D-78457 Konstanz, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Rosseeva
authors.affiliation: Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Buder
authors.affiliation: Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Scheler
authors.affiliation: Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Kniep
mesh_terms: D001031:Apatites / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D003460:Crystallization; D005780:Gelatin / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry
chemical_list: D001031:Apatites; D005780:Gelatin; C025105:fluorapatite