At the Intersection of Natural Structural Coloration and Bioengineering

Abstract

Most of us get inspired by and interact with the world around us based on visual cues such as the colors and patterns that we see. In nature, coloration takes three primary forms: pigmentary coloration, structural coloration, and bioluminescence. Typically, pigmentary and structural coloration are used by animals and plants for their survival; however, few organisms are able to capture the nearly instantaneous and visually astounding display that cephalopods (e.g., octopi, squid, and cuttlefish) exhibit. Notably, the structural coloration of these cephalopods critically relies on a unique family of proteins known as reflectins. As a result, there is growing interest in characterizing the structure and function of such optically-active proteins (e.g., reflectins) and to leverage these materials across a broad range of disciplines, including bioengineering. In this review, I begin by briefly introducing pigmentary and structural coloration in animals and plants as well as highlighting the extraordinary appearance-changing capabilities of cephalopods. Next, I outline recent advances in the characterization and utilization of reflectins for photonic technologies and and discuss general strategies and limitations for the structural and optical characterization of proteins. Finally, I explore future directions of study for optically-active proteins and their potential applications. Altogether, this review aims to bring together an interdisciplinary group of researchers who can resolve the fundamental questions regarding the structure, function, and self-assembly of optically-active protein-based materials.

A Mini-Review on Reflectins, from Biochemical Properties to Bio-Inspired Applications

“…(1) It is necessary to understand the design of biological materials or biological materials with dynamic and self-regulating functions from a synthetic perspective. Basic research should be carried out to better understand reflectins’ structure, self-assembly, and their tendency to form aggregates under physiological conditions [ 27 , 65 ]. (2) As membrane envelopes serve as amplifiers to the range of tunable sizes of reflectin assemblies [ 22 ], it is necessary to decipher the mechanism of how reflectins interact with cytomembranes.…”

“…Moreover, albeit not for photonic applications, the construction of reflectin assemblies in cells can establish models for wider research fields. As Atrouli et al suggested in their enlightening review, the dynamic self-assembly properties or tendency to form aggregates in vitro causes the potential surrogates of reflectins to simulate the pathogenesis of neurological disorders, because these diseases are supposed to be caused by the formation of misfolded protein aggregates [ 27 ]. Now that we can construct intracellular reflectin-based aggregates in cells, we may better understand how these misfolded proteins trigger neurological diseases under physiological conditions.…”

“…In a biochemical scope, Dr. Morse and his colleagues have accomplished brilliant works and reviewed relevant basic studies [ 14 ]. From the perspective of bio-inspired applications, Chatterjee et al sorted out efforts to apply reflectins as materials to establish color-changing coatings and devices [ 26 ], which is also briefly mentioned by some other reviews [ 27 , 28 , 29 , 30 ]. However, the relationship between the biological prototypes and these man-made systems is poorly considered.…”

Color Biomimetics in Textile Design: Reproduction of Natural Plant Colors through Instrumental Colorant Formulation

“…Color biomimetics in textiles encompasses diverse approaches, spanning from pigmentary to structural coloration, dynamic camouflage, and bioluminescence [9][10][11]. Pigmentary coloration refers to a photochemical process involving selective absorption of incident light, whereas in structural coloration, the process is photophysical, and color depends on how incident light interacts with the physical structure [12][13][14].…”

Investigation of the origin of structural colors in calliphoridae flies for bioinspiration

“…In our daily lives, we observe colors that are generated by two different mechanisms: structural (physical) and pigmentary (chemical) [1][2][3][4]. This paper focuses on structural colorations, which result from the interaction between light and matter.…”