Although many animals have evolved intrinsic transparency for the purpose of concealment, the development of dynamic, that is, controllable and reversible, transparency for living human cells and tissues has remained elusive to date. Here, by drawing inspiration from the structures and functionalities of adaptive cephalopod skin cells, we design and engineer human cells that contain reconfigurable protein-based photonic architectures and, as a result, possess tunable transparency-changing and light-scattering capabilities. Our findings may lead to the development of unique biophotonic tools for applications in materials science and bioengineering and may also facilitate an improved understanding of a wide range of biological systems.

High-temperature data retention is a critical hurdle for the commercialization of emerging nonvolatile memories. For Conductive-Bridge RAM (CBRAM) [1], we discuss hightemperature retention in terms of the physics of quantum point contacts, and we report on a family of CBRAM cells that achieve excellent retention at temperatures exceeding 200ºC.

Naturally occurring and recombinant protein-based materials are frequently employed for the study of fundamental biological processes and are often leveraged for applications in areas as diverse as electronics, optics, bioengineering, medicine, and even fashion. Within this context, unique structural proteins known as reflectins have recently attracted substantial attention due to their key roles in the fascinating color-changing capabilities of cephalopods and their technological potential as biophotonic and bioelectronic materials. However, progress toward understanding reflectins has been hindered by their atypical aromatic and charged residue-enriched sequences, extreme sensitivities to subtle changes in environmental conditions, and well-known propensities for aggregation. Herein, we elucidate the structure of a reflectin variant at the molecular level, demonstrate a straightforward mechanical agitation-based methodology for controlling this variant’s hierarchical assembly, and establish a direct correlation between the protein’s structural characteristics and intrinsic optical properties. Altogether, our findings address multiple challenges associated with the development of reflectins as materials, furnish molecular-level insight into the mechanistic underpinnings of cephalopod skin cells’ color-changing functionalities, and may inform new research directions across biochemistry, cellular biology, bioengineering, and optics.

Biomolecular proton conducting materials have been touted as promising for seamlessly and directly interfacing natural biological systems with traditional artificial electronics. As such, proton conduction has been explored for a variety of protein- and polypeptide-based materials. Within this context, cephalopod structural proteins called reflectins have demonstrated several favorable properties, including outstanding electrical figures of merit as proton conductors and intrinsic biocompatibility with cellular systems. However, the processing of reflectins into films has typically used low-throughput material-intensive strategies and has often required organic solvents. Herein, we report the preparation of devices from active layers fabricated via inkjet printing of reflectin solubilized in water and the systematic evaluation of their electrical performance. Taken together, our findings represent a step forward in the manufacturing and development of unconventional bioelectronic platforms from the reflectin family of proteins.