Biomimetic Colorants and Coatings Designed with Cephalopod-Inspired Nanocomposites.

Brilliant and dynamic colors in nature have stimulated the design of dyes and pigments with broad applications ranging from electronic displays to apparel. Inspired by the nanostructured pigment granules present in cephalopod chromatophore organs, we describe the design and fabrication of biohybrid colorants containing the cephalopod-specific pigment, xanthommatin (Xa), encased within silica-based nanostructures. We employed a biomimetic approach to encapsulate Xa with amine-terminated polyamidoamine (PAMAM) dendrimer templates, which helped stabilize the pigment during encapsulation. Depending on the concentration of Xa used in the reaction, the resultant biohybrid nanomaterials generated a range of neutral colors of differing hues. When applied as coatings, these colorants can be triggered to change color from yellow/gold to red in the presence of a chemical reducing agent, as we leverage the natural redox-dependent color change of Xa. Altogether, these capabilities demonstrated the ability to process biochromes like Xa as nanomaterials that can be applied as coatings with a tunable and dynamic range.