Carminic Acid Based Red Dye from Scale Insects Detected in Red Ruby-Crowned Kinglet Feathers by Surface-Enhanced Raman Scattering

Xuanyi Wu; Santiago Sanchez-Cortes; Ioanna Kakoulli

doi:10.1002/cplu.202100178

Carminic Acid Based Red Dye from Scale Insects Detected in Red Ruby-Crowned Kinglet Feathers by Surface-Enhanced Raman Scattering

Chempluschem. 2021 Jul 19;86(8):1074-1079. doi: 10.1002/cplu.202100178. Online ahead of print.

Authors

Xuanyi Wu^{1

2}, Santiago Sanchez-Cortes³, Ioanna Kakoulli^{1

2}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), 410 Westwood Plaza, Los Angeles, CA, USA.
² Molecular and Nano Archaeology Laboratory UCLA, 410 Westwood Plaza, Los Angeles, CA, USA.
³ Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano, 121, 28006, Madrid, Spain.

PMID: 34402223
DOI: 10.1002/cplu.202100178

Abstract

In most birds, red feather color is linked to diet and attributed to carotenoids contained in plants and fruits. In the red crown feathers of the Ruby-crowned Kinglet (Regulus calendula), a new biopigment was identified based on carminic acid, the main coloring compound of cochineal (Dactylopius coccus) and other scale insects. This has revealed a potential new class of carminic acid-based biopigments, not previously identified in feathers. In this research, red crown feathers of a Ruby-crowned Kinglet were analyzed by surface-enhanced Raman scattering (SERS) employing synthesized silver star-shaped colloids as the nanoplasmonic platform. Results indicated peaks at 450, 670, 1290-1312, 1355, 1410, 1570, 1620 cm^-1 in the feather SERS spectra characteristic of carminic acid. SERS has proven to be an extremely sensitive, non-destructive technique for the identification of different feather biopigments, even at trace quantities and in the presence of other predominant coloring substances.

Keywords: Raman spectroscopy; dyes/pigments; feathers; fiber optics reflectance spectroscopy; ornithology.

Abstract

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