Dynamic self-assembly of reflectins and their contribution to cephalopods coloration

Color modulation in cephalopods is driven by the coordinated action of specialized skin cells that contribute to both pigment-based coloration (chromatophores) and structural coloration (iridophores and leucophores). Reflectins, a family of proteins unique to cephalopods, are highly expressed in these biophotonic structures. In vivo, dynamic structural coloration is regulated by the reversible assembly of reflectin-based structures, which are triggered by phosphorylation events. In vitro studies have shown that reflectins can self-assemble into a variety of architectures from nano- to macro-scales, including colloidal assemblies, liquid–liquid coacervates and hydrogels. Such assembly is responsive to chemical and physical stimuli, such as pH, ionic strength, and mechanical stress. In this review, we highlight the mechanisms of reflectin self-assembly in vitro, using both full-length sequences and truncated variants, and discuss emerging opportunities for engineering novel dynamic biomimetic materials.