title: How amelogenin orchestrates the organization of hierarchical elongated microstructures of apatite.
abstract: Amelogenin (Amel) accelerates the nucleation of hydroxyapatite (HAP) in supersaturated solutions of calcium phosphate (Ca-P), shortening the induction time (delay period), under near-physiological conditions of pH, temperature, and ionic strength. Hierarchically organized Amel and amorphous calcium phosphate (ACP) nanorod microstructures are formed involving a coassembly of Amel-ACP particles at low supersaturations and low protein concentrations in a slow, well-controlled, constant composition (CC) crystallization system. At the earliest nucleation stages, the CC method allows the capture of prenucleation clusters and intermediate nanoclusers, spherical nanoparticles, and nanochains prior to enamel-like nanorod microstructure formations at later maturation stages. Amel-ACP nanoscaled building blocks are formed spontaneously by synergistic interactions between flexible Amel protein molecules and Ca-P prenucleation clusters, and these spherical nanoparticles evolve by orientated aggregation to form nanochains. Our results suggest that, in vivo, Amel may determine the structure of enamel by controlling prenucleation cluster aggregation at the earliest stages by forming stable Amel-ACP microstructures prior to subsequent crystal growth and mineral maturation.
authors.affiliation: Department of Chemistry, The State University of New York at Buffalo, Amherst, New York 14260, USA.
authors.forename: Xiudong
authors.initials: X
authors.lastname: Yang
authors.forename: Lijun
authors.initials: L
authors.lastname: Wang
authors.forename: Yueling
authors.initials: Y
authors.lastname: Qin
authors.forename: Zhi
authors.initials: Z
authors.lastname: Sun
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Henneman
authors.forename: Janet
authors.initials: J
authors.lastname: Moradian-Oldak
authors.forename: George H
authors.initials: GH
authors.lastname: Nancollas
mesh_terms: D053523:Amelogenin / Q000737:chemistry*; D003460:Crystallization; D003743:Dental Enamel / Q000737:chemistry; D006882:Hydroxyapatites / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D053523:Amelogenin; D006882:Hydroxyapatites