Chemically Hydrophobic and Structurally Antireflective Nanocoatings in Papilio Butterflies

Moth-eye nanostructures, known for their biological antireflective properties, are formed by a self-assembly
mechanism. Understanding and replicating this mechanism on artificial surfaces open avenues for the engineering of bioinspired
multifunctional nanomaterials. Analysis of corneal nanocoatings from butterflies of the genus Papilio reveals a variety of
nanostructures with uniformly strong antiwetting properties accompanied by varying antireflective functionalities. Interestingly, while
the structural features of the nanocoatings determine the antireflective functionality, the antiwetting is controlled by their chemical
composition, an unusual trait among insects. The availability of whole-genome sequences for several Papilio species allowed us to
identify the corneal proteome, including the protein responsible for the nanocoating assembly, CPR67A. The high hydrophobicity of
this protein, coupled with its capacity to mediate self-assembly, underlies the formation of unique multifunctional Papilio
nanostructures and permits the development of bioinspired artificial nanocoatings. Our findings pave the way for biomimetic
nanomaterials and guide the engineering of nanostructures with predefined functionalities.