Cephalopods possess unrivaled camouflage and signaling abilities that are enabled by their sophisticated skin architecture, wherein multiple layers contain chromatophore pigment cells (which act like color filters, and are part of larger chromatophore organs) and different types of reflective cells called iridocytes (which act like biological Bragg stacks) and leucophores (which act like broadband Lambertian diffusers). The optical functionality of these cells (and thus cephalopod skin) is enabled by subcellular structures, which are partially composed of a class of unusual structural proteins known as reflectins. Herein, we highlight studies that investigate reflectins’ structure-function relationships, particularly within the context of stimuli-induced color changing devices and systems. Specifically, we will discuss the how the self-assembly of these proteins enables the manipulation of their light reflecting properties. In addition, we will discuss the multi-faceted properties of this unique class of proteins (e.g. proton conductivity), challenges in working with them, and the future potential of these proteins. Overall, our findings hold relevance for the development of protein-based optoelectronic technologies.
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