title: Protein-free formation of bone-like apatite: New insights into the key role of carbonation.
abstract: The nanometer-sized plate-like morphology of bone mineral is necessary for proper bone mechanics and physiology. However, mechanisms regulating the morphology of these mineral nanocrystals remain unclear. The dominant hypothesis attributes the size and shape regulation to organic-mineral interactions. Here, we present data supporting the hypothesis that physicochemical effects of carbonate integration within the apatite lattice control the morphology, size, and mechanics of bioapatite mineral crystals. Carbonated apatites synthesized in the absence of organic molecules presented plate-like morphologies and nanoscale crystallite dimensions. Experimentally-determined crystallite size, lattice spacing, solubility and atomic order were modified by carbonate concentration. Molecular dynamics (MD) simulations and density functional theory (DFT) calculations predicted changes in surface energy and elastic moduli with carbonate concentration. Combining these results with a scaling law predicted the experimentally observed scaling of size and energetics with carbonate concentration. The experiments and models describe a clear mechanism by which crystal dimensions are controlled by carbonate substitution. Furthermore, the results demonstrate that carbonate substitution is sufficient to drive the formation of bone-like crystallites. This new understanding points to pathways for biomimetic synthesis of novel, nanostructured biomaterials.
authors.affiliation: Dept. of Orthopedic Surgery, Columbia University, New York, NY 10032, USA. Electronic address: Alix.c.deymier@gmail.com.
authors.forename: Alix C
authors.initials: AC
authors.lastname: Deymier
authors.affiliation: Dept. of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Nair
authors.affiliation: Dept. of Materials, Imperial College, London SW7 2AZ, UK.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Depalle
authors.affiliation: Dept. of Civil and Environmental Engineering, MIT, Boston, MA 02139, USA.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Qin
authors.affiliation: Dept. of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130, USA.
authors.forename: Kashyap
authors.initials: K
authors.lastname: Arcot
authors.affiliation: CIRIMAT, Université de Toulouse, CNRS/UPS/INP, Ensiacet, Toulouse 31030, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Drouet
authors.affiliation: Dept. of Chemistry, Franklin and Marshall College, Lancaster, PA 17604, USA.
authors.forename: Claude H
authors.initials: CH
authors.lastname: Yoder
authors.affiliation: Dept. of Civil and Environmental Engineering, MIT, Boston, MA 02139, USA.
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Buehler
authors.affiliation: Dept. of Orthopedic Surgery, Columbia University, New York, NY 10032, USA.
authors.forename: Stavros
authors.initials: S
authors.lastname: Thomopoulos
authors.affiliation: Dept. of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130, USA.
authors.forename: Guy M
authors.initials: GM
authors.lastname: Genin
authors.affiliation: Dept. of Earth and Planetary Sciences, Washington University, St Louis, MO 63130, USA. Electronic address: pasteris@levee.wustl.edu.
authors.forename: Jill D
authors.initials: JD
authors.lastname: Pasteris
mesh_terms: D001031:Apatites / Q000737:chemistry*; D001842:Bone and Bones / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry*; D003460:Crystallization; D055119:Elastic Modulus; D011208:Powders; D011506:Proteins / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D002254:Carbonates; D011208:Powders; D011506:Proteins
keywords: Biomineralization; Bone; Calcium phosphate; Carbonate; Substitution