title: Amino acid synergetic effect on structure, morphology and surface properties of biomimetic apatite nanocrystals.
abstract: Alanine, arginine and aspartic acid have been used as co-reagents during the synthesis of a biomimetic calcium-deficient hydroxyapatite (CDHA) for the synergistic coupling of synthesis and functionalization. The surface and bulk characterizations are consistent with a binding model in which the amino acid is preferentially bound to the CDHA nanocrystal surface by its lateral chain group. The zeta-potential measurements show that the amino acid-functionalized CDHA surface charge shifts towards neutral compared to CDHA synthesized in the absence of amino acids. Amino acids bound to the crystal induce crystal growth inhibition predominantly at the Ca-rich surfaces during the initial stages of crystallization. Moreover, high-resolution transmission electron microscopy measurements suggest a model for needle-shaped CDHA nanocrystals formation in the presence of either arginine or aspartic acid based on the oriented aggregation of primary crystallite domains specifically along the c-axis direction and the self-assembly of preformed nanoparticles. The results have significant importance for the control of the shape, morphology and aggregation of the CDHA nanocrystals, while the observed surface modifications are of marked importance for the nature, stability and reactivity of the functionalized surfaces produced.
authors.affiliation: Department of Chemistry G. Ciamician, Alma Mater Studiorum, University of Bologna, Via Selmi 2, 40126 Bologna, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Palazzo
authors.forename: Dominic
authors.initials: D
authors.lastname: Walsh
authors.forename: Michele
authors.initials: M
authors.lastname: Iafisco
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Foresti
authors.forename: Luca
authors.initials: L
authors.lastname: Bertinetti
authors.forename: Gianmario
authors.initials: G
authors.lastname: Martra
authors.forename: Claudia Letizia
authors.initials: CL
authors.lastname: Bianchi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cappelletti
authors.forename: Norberto
authors.initials: N
authors.lastname: Roveri
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D017886:Durapatite / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D013055:Spectrophotometry, Infrared; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000596:Amino Acids; D017886:Durapatite; D002118:Calcium