UC Irvine

Cephalopods possess astounding camouflage abilities that are enabled by their sophisticated skin, which contains organs called chromatophores and cells called iridocytes and leucophores. The light reflecting and scattering capabilities of some of these cells are facilitated by subcellular structures primarily composed of an unusual structural protein known as reflectin. Previously it was shown that reflectin can be expressed in human cells, where it self-assembles into structures that are responsive to the external salt stimulation. Nevertheless, the three-dimensional characterization and control of the reflectin aggregation in human cells (via external stimulation and genetic modifications) have not been well characterized at the intracellular level. Here, we three-dimensionally characterize the subcellular morphology and arrangement of reflectin-based structures within engineered human cells and demonstrate external control over the self-assembly and refractive index distributions of these structures upon chemical stimulation and genetic engineering. Our findings may lead to the development of unique biomolecular tools for label-free holotomography imaging, facilitate understanding of reversible transparencies in cephalopods, and hold potential for obtaining dynamic living materials with customizable optical properties (e.g., camouflage and tunable transparency) for various applications in biotechnology, synthetic biology, and optical engineering.