Structure, function, and self-assembly of single network gyroid ( I 4 ₁ 32) photonic crystals in butterfly wing scales

Abstract

Complex three-dimensional biophotonic nanostructures produce the vivid structural colors of many butterfly wing scales, but their exact nanoscale organization is uncertain. We used small angle X-ray scattering (SAXS) on single scales to characterize the 3D photonic nanostructures of five butterfly species from two families (Papilionidae, Lycaenidae). We identify these chitin and air nanostructures as single network gyroid (I4 1 32) photonic crystals. We describe their optical function from SAXS data and photonic band-gap modeling. Butterflies apparently grow these gyroid nanostructures by exploiting the self-organizing physical dynamics of biological lipid-bilayer membranes. These butterfly photonic nanostructures initially develop within scale cells as a core-shell double gyroid (Ia3d), as seen in block-copolymer systems, with a pentacontinuous volume comprised of extracellular space, cell plasma membrane, cellular cytoplasm, smooth endoplasmic reticulum (SER) membrane, and intra-SER lumen. This double gyroid nanostructure is subsequently transformed into a single gyroid network through the deposition of chitin in the extracellular space and the degeneration of the rest of the cell. The butterflies develop the thermodynamically favored double gyroid precursors as a route to the optically more efficient single gyroid nanostructures. Current approaches to photonic crystal engineering also aim to produce single gyroid motifs. The biologically derived photonic nanostructures characterized here may offer a convenient template for producing optical devices based on biomimicry or direct dielectric infiltration.biological meta-materials | organismal color | biomimetics | biological cubic mesophases

Structure and optical function of amorphous photonic nanostructures from avian feather barbs: a comparative small angle X-ray scattering (SAXS) analysis of 230 bird species

“…10-15 mm 3 but vary with taxon [49]). The azimuthally averaged scattering profiles were calculated from the CCD-collected two-dimensional SAXS speckle diffraction patterns using the freely available Matlabimplemented software, XPCSGUI, developed by beamline 8-ID (http://8id.xor.aps.anl.gov/UserInfo/Analysis/) at 200 equal q-partitions, and with customized masks to filter out the beam stop [15,38,50]. SAXS data from the feathers of Cittura cyanotis and the yellow throat of Psarisomus dalhousiae (see electronic supplementary material, tables S1 and S2) were collected using a 7.35 keV beam (1.68 Å , 50 mm horizontal  50 mm vertical, 9.24 m camera length, 50  0.1 s exposures) on a Pilatus2M detector at beamline I22 of the Diamond Light Source, Didcot, UK.…”

Direct Laser Desorption Ionization of Endogenous and Exogenous Compounds from Insect Cuticles: Practical and Methodologic Aspects

“…For example, pigmentation in flies, bees, and wasps is attributed to the presence of aromatic compounds heavily involved in cross-linking of the extracellular matrix, as well as to the occurrence of melanin in black-colored cuticle [35]. In the case of moth and butterfly wings, electron microscopy has revealed that cuticular structures are arrayed in multilayers or contain photonic crystals [36], both of which produce optical interference and can contribute to iridescent coloring.…”

Tunable structural color in organisms and photonic materials for design of bioinspired materials

“…For example, gyroid and related phases have been reported recently [91,92]. Galusha et al have grown diamond-structured 3D photonic crystals by replicating the beetle shell using the sol-gel technique [93].…”