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Djeghdi K, Schumacher C, Bauernfeind V, Gunkel I, Wilts BD, Steiner U. Anoplophora graafi longhorn beetle coloration is due to disordered diamond-like packed spheres. SOFT MATTER 2024; 20:2509-2517. [PMID: 38389437 PMCID: PMC10933740 DOI: 10.1039/d4sm00068d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 02/16/2024] [Indexed: 02/24/2024]
Abstract
While artificial photonic materials are typically highly ordered, photonic structures in many species of birds and insects do not possess a long-range order. Studying their order-disorder interplay sheds light on the origin of the photonic band gap. Here, we investigated the scale morphology of the Anoplophora graafi longhorn beetle. Combining small-angle X-ray scattering and slice-and-view FIB-SEM tomography with molecular dynamics and optical simulations, we characterised the chitin sphere assemblies within blue and green A. graafi scales. The low volume fraction of spheres and the number of their nearest neighbours are incompatible with any known close-packed sphere morphology. A short-range diamond lattice with long-range disorder best describes the sphere assembly, which will inspire the development of new colloid-based photonic materials.
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Affiliation(s)
- Kenza Djeghdi
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
- National Competence Center in Bioinspired Materials, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Cédric Schumacher
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
| | - Viola Bauernfeind
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
- National Competence Center in Bioinspired Materials, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Ilja Gunkel
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
- National Competence Center in Bioinspired Materials, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
| | - Bodo D Wilts
- National Competence Center in Bioinspired Materials, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
- Department of Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Straße 2A, 5020 Salzburg, Austria.
| | - Ullrich Steiner
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
- National Competence Center in Bioinspired Materials, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
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Jessop AL, Millsteed AJ, Kirkensgaard JJK, Shaw J, Clode PL, Schröder-Turk GE. Composite material in the sea urchin Cidaris rugosa: ordered and disordered micrometre-scale bicontinuous geometries. J R Soc Interface 2024; 21:20230597. [PMID: 38471532 PMCID: PMC10932713 DOI: 10.1098/rsif.2023.0597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 02/12/2024] [Indexed: 03/14/2024] Open
Abstract
The sponge-like biomineralized calcite materials found in echinoderm skeletons are of interest in terms of both structure formation and biological function. Despite their crystalline atomic structure, they exhibit curved interfaces that have been related to known triply periodic minimal surfaces. Here, we investigate the endoskeleton of the sea urchin Cidaris rugosa that has long been known to form a microstructure related to the Primitive surface. Using X-ray tomography, we find that the endoskeleton is organized as a composite material consisting of domains of bicontinuous microstructures with different structural properties. We describe, for the first time, the co-occurrence of ordered single Primitive and single Diamond structures and of a disordered structure within a single skeletal plate. We show that these structures can be distinguished by structural properties including solid volume fraction, trabeculae width and, to a lesser extent, interface area and mean curvature. In doing so, we present a robust method that extracts interface areas and curvature integrals from voxelized datasets using the Steiner polynomial for parallel body volumes. We discuss these very large-scale bicontinuous structures in the context of their function, formation and evolution.
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Affiliation(s)
- Anna-Lee Jessop
- School of Mathematics, Statistics, Chemistry and Physics, Murdoch University, Murdoch, Australia
| | - Allan J. Millsteed
- School of Mathematics, Statistics, Chemistry and Physics, Murdoch University, Murdoch, Australia
| | - Jacob J. K. Kirkensgaard
- Niels Bohr Institute, University of Copenhagen, Kobenhavn, Denmark
- Department of Food Science, University of Copenhagen, Kobenhavn, Denmark
| | - Jeremy Shaw
- Centre for Microscopy, Characterisation, and Analysis, University of Western Australia, Perth, Australia
| | - Peta L. Clode
- Centre for Microscopy, Characterisation, and Analysis, University of Western Australia, Perth, Australia
- School of Biological Sciences, University of Western Australia, Perth, Australia
| | - Gerd E. Schröder-Turk
- School of Mathematics, Statistics, Chemistry and Physics, Murdoch University, Murdoch, Australia
- Research School of Physics, The Australian National University, Canberra, Australia
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