Production and processing of zein nanoparticles as structural colorants.

The emergence of structural coloration in nature requires precise control over material selection, processing, assembly, and distribution to create monodispersed nanostructured arrays. Such control has been historically difficult to replicate and scale for materials applications due to feedstock heterogeneity or complex assembly conditions. We explore the application and processing of an unconventional biomaterial, zein protein, as a template for structural coloration that may overcome these challenges. We leverage the spontaneous assembly of zein as nanoparticles using antisolvent precipitation to create structures with diameters ranging from 180 to 220 nm-a size regime that enables structural color formation. When cast as films, the nanoparticles produce amorphous coatings that display a reflectance peak at 410 nm indicative of violet-blue coloration, highlighting a unique avenue for these biomaterials as structural colorants.