Emergence of large-scale chirality in photonic crystals in insects and butterflies

The biological world is filled with chiral structures, formed from a soup of building blocks that usually include both achiral and chiral molecules. In this talk, I will focus on chiral structures that emerge at the scale of hundreds of nanometers in solid insect nanostructures, and that then act as biophotonic crystals. Of particular interest in this context are the Gyroid nanosolids that form in several butterflies, as highly ordered 3D network-like porous materials, and which then contribute in particular to green coloration. I will review in particular what we understand (and not understand) about the formation of these structures; in this context, the fortuitous discovery of a butterfly nanostructure in Thecla Opisena is noteworthy. It appears to show a time-frozen snapshot of various stages of the formation which allows us to infer properties of the formation from high-resolution electron and X-ray tomography images.

Wilts et al, Science Advances 3, e1603119 (2017)
Winter et al, PNAS, 112, 12911 (2015)