Identification and classification of silks using infrared spectroscopy.
Lepidopteran silks number in the thousands and display a vast diversity of structures, properties and industrial potential. To map this remarkable biochemical diversity, we present an identification and screening method based on the infrared spectra of native silk feedstock and cocoons. Multivariate analysis of over 1214 infrared spectra obtained from 35 species allowed us to group silks into distinct hierarchies and a classification that agrees well with current phylogenetic data and taxonomies. This approach also provides information on the relative content of sericin, calcium oxalate, phenolic compounds, poly-alanine and poly(alanine-glycine) β-sheets. It emerged that the domesticated mulberry silkmoth Bombyx mori represents an outlier compared with other silkmoth taxa in terms of spectral properties. Interestingly, Epiphora bauhiniae was found to contain the highest amount of β-sheets reported to date for any wild silkmoth. We conclude that our approach provides a new route to determine cocoon chemical composition and in turn a novel, biological as well as material, classification of silks.
Department of Life Sciences, Imperial College London, London SW7 2AZ, UK Department of Zoology, University of Oxford, Oxford OX1 3PS, UK m.boulet-audet@imperial.ac.uk.
Maxime
M
Boulet-Audet
Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
Fritz
F
Vollrath
Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK.
Chris
C
Holland
D000818:Animals; D001097:Arachnida / Q000378:metabolism*; D012831:Bombyx / Q000378:metabolism; D002129:Calcium Oxalate / Q000737:chemistry; D009036:Moths / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D010636:Phenols / Q000737:chemistry; D010802:Phylogeny; D047030:Sericins / Q000737:chemistry; D047011:Silk / Q000737:chemistry* / Q000145:classification*; D013055:Spectrophotometry, Infrared
D010455:Peptides; D010636:Phenols; D047030:Sericins; D047011:Silk; D002129:Calcium Oxalate
Cocoon; Lepidopteran; Multivariate analysis; Phylogenetic; Silkworm