Insect wings are interesting and attractive as unique examples of bioinspired and biomimetic materials. They exhibit multi-functional features and provide a natural model for developing a functional device based on organic polymers. Although there are many studies on the structures of insect wings using spectroscopic or morphological methods, only a few focused on their chiral properties.
The present work is unprecedented in that it focused on the supramolecular chiral aspect of a targeted insect hindwing sample. We report the application of a multi-dimensional vibrational circular dichroism system (MultiD-VCD) to the hindwings of an insect (Anomala albopilosa (male) ). The MultiD-VCD system with a QCL (quantum cascade laser) was recently developed for the microscopic two-dimensional mapping of VCD signals. The mapping was performed at the spatial resolution of 100 mm on insect hindwing tissue. As a result, it was revealed that the insect hindwing is composed of segregated microdomains consisting of proteins with different secondary structures. The uniqueness of the present method is demonstrated by the following aspects: (i) the observed microscopic distribution of proteins is unattainable by conventional FT-IR spectroscopy; (ii) the identification of a secondary structure of a protein is realized in situ with no pretreatment of the biological sample, such as coating, grinding or solvent extraction.
The Journal of Physical Chemistry Letters
Subject of Research
Mapping of Supramolecular Chirality in Insect Wings by Microscopic Vibrational Circular Dichroism Spectroscopy: Heterogeneity in Protein Distribution