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Guanine‐Based Biogenic Photonic‐Crystal Arrays in Fish and Spiders
Author(s) -
LevyLior Avital,
Shimoni Eyal,
Schwartz Osip,
GavishRegev Efrat,
Oron Dan,
Oxford Geoff,
Weiner Steve,
Addadi Lia
Publication year - 2010
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200901437
Subject(s) - materials science , guanine , amorphous solid , crystal (programming language) , fish <actinopterygii> , anhydrous , crystallography , integument , stack (abstract data type) , photonic crystal , crystal structure , structural coloration , optics , optoelectronics , biology , chemistry , anatomy , organic chemistry , nucleotide , biochemistry , physics , fishery , gene , computer science , programming language
Abstract Biological photonic systems composed of anhydrous guanine crystals evolved separately in several taxonomic groups. Here, two such systems found in fish and spiders, both of which make use of anhydrous guanine crystal plates to produce structural colors, are examined. Measurements of the photonic‐crystal structures using cryo‐SEM show that the crystal plates in both fish skin and spider integument are ∼20‐nm thick. The reflective unit in the fish comprises stacks of single plates alternating with ∼230‐nm‐thick cytoplasm layers. In the spiders the plates are formed as doublet crystals, cemented by 30‐nm layers of amorphous guanine, and are stacked with ∼200 nm of cytoplasm between crystal doublets. They achieve light reflective properties through the control of crystal morphology and stack dimensions, reaching similar efficiencies of light reflectivity in both fish skin and spider integument. The structure of guanine plates in spiders are compared with the more common situation in which guanine occurs in the form of relatively unorganized prismatic crystals, yielding a matt white coloration.