Squid-Inspired Engineering of Optically-Dynamic Mammalian Cells
Cephalopods (e.g., squid, octopus, and cuttlefish) possess astounding camouflage and signaling capabilities, which are enabled by their sophisticated skin architecture. Specifically, the color-changing capabilities of cephalopods are enabled by chromatophore pigment cells (as part of larger chromatophore organs) and different types of reflective cells, called iridocytes and leucophores. The optical functionality of these cells (and thus cephalopod skin) critically rely upon subcellular structures composed of a class of unusual structural proteins known as reflectins. Herein, I detail strategies for the engineering of optically-dynamic mammalian cells containing reflectin-based architectures. For this purpose, I begin by establishing a relationship between the self-assembled structure and optical function of a prototypical reflectin variant and demonstrate that this protein can be expressed within mammalian cells. Next, I establish that the full-length reflectin isoform, from which the prototypical variant is derived, can be externally stimulated to scatter light and that mammalian cells can also be engineered to have such optically-dynamic capabilities. Furthermore, I leverage existing methods for predicting the refractive index of a wild-type reflectin isoform to gain insight into the correlation between the optical properties of the protein when assembled into nanoparticles in vitro and when expressed within mammalian cells. Finally, I explore the mechanism by which reflectin-expressing cells are able to reorganize the protein and design a bioelectronic platform to control this process. Altogether, these findings offer robust methodologies for the production of reflectins and hold promise for the future development of biophotonic and biomedical technologies based on and inspired by reflectins.