Towards Understanding a Dynamic Cephalopod Protein Reflectin
Biomaterials have the unique ability to actively respond to environmental stimuli for the purpose of motility, metabolism, and, in the case of some animals, camouflage. Proteins often serve these critical biological functions because of their multi-scale, hierarchical functionality and specific chemical activity. Cephalopods- octopus, cuttlefish, and squid- posses a unique family of proteins known as reflectins which imbue these creatures with their remarkable camouflage abilities. The cephalopod, therefore, may serve both as a source of inspiration towards developing new materials and a subject of study to better understand the activity and self-assembly of proteins in general. Herein, a selection of cephalopod-inspired materials is reviewed from the literature. The merits, unique properties, and challenges of developing these dynamic materials are discussed. Next, an exotic protein implicated as the active material in biophotonic organelles of a loliginid squid known as reflectin isoform A1 (RfA1) is characterized. By deploying a variety of advanced X-ray scattering techniques and a suite of biophysical characterizing methods, the geometry and self-assembly of this protein is observed both in the solvated and solid state. Altogether, this work holds relevance towards fundamentally understanding the reflectin protein family and towards developing the field of self-actuating, reconfigurable materials.