title: Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells.
abstract: Intricate biomineralization processes in molluscs engineer hierarchical structures with meso-, nano- and atomic architectures that give the final composite material exceptional mechanical strength and optical iridescence on the macroscale. This multiscale biological assembly inspires new synthetic routes to complex materials. Our investigation of the prism-nacre interface reveals nanoscale details governing the onset of nacre formation using high-resolution scanning transmission electron microscopy. A wedge-polishing technique provides unprecedented, large-area specimens required to span the entire interface. Within this region, we find a transition from nanofibrillar aggregation to irregular early-nacre layers, to well-ordered mature nacre suggesting the assembly process is driven by aggregation of nanoparticles (∼50-80 nm) within an organic matrix that arrange in fibre-like polycrystalline configurations. The particle number increases successively and, when critical packing is reached, they merge into early-nacre platelets. These results give new insights into nacre formation and particle-accretion mechanisms that may be common to many calcareous biominerals.
authors.affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Hovden
authors.affiliation: Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA.|Department of Materials Science and Engineering, Institute of Glass and Ceramics, Friedrich-Alexander-University Erlangen-Nürnberg, 91058 Erlangen, Germany.
authors.forename: Stephan E
authors.identifier: http://orcid.org/0000-0002-3747-8097
authors.initials: SE
authors.lastname: Wolf
authors.affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Holtz
authors.affiliation: UMR CNRS 6282 Biogéosciences, Université de Bourgogne Franche-Comté, 6 Boulevard Gabriel, 21000 Dijon, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Marin
authors.affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.|Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA.
authors.forename: David A
authors.identifier: http://orcid.org/0000-0003-4129-0473
authors.initials: DA
authors.lastname: Muller
authors.affiliation: Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA.|Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA.
authors.forename: Lara A
authors.initials: LA
authors.lastname: Estroff
mesh_terms: D060105:Animal Shells / Q000737:chemistry / Q000648:ultrastructure*; D000818:Animals; D008855:Microscopy, Electron, Scanning; D008974:Mollusca / Q000737:chemistry / Q000648:ultrastructure*; D060734:Nacre / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure*
chemical_list: D060734:Nacre