A bioinspired and hierarchically structured shape-memory material

• Published in: Nature materials Vol. 20; no. 2; pp. 242 - 249
• Main Authors: Cera, Luca, Gonzalez, Grant M., Liu, Qihan, Choi, Suji, Chantre, Christophe O., Lee, Juncheol, Gabardi, Rudy, Choi, Myung Chul, Shin, Kwanwoo, Parker, Kevin Kit
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2021; Nature Publishing Group
• Subjects: 639/301/54; 639/638; Actuation; Biocompatibility; Bioengineering; Biomaterials; Biomimetics; Chemistry and Materials Science; Condensed Matter Physics; Fabrication; Fibers; Keratin; Keratins - chemistry; Materials Science; Nanotechnology; Optical and Electronic Materials; Printing, Three-Dimensional; Reconfiguration; Scaffolds; Self-assembly; Shape memory; Shear stress; Smart materials; Smart Materials - chemistry; Spinning (materials); Structural hierarchy; Textiles; Three dimensional printing; Tissue Engineering; Tissue Scaffolds - chemistry
• ISSN: 1476-1122; 1476-4660; 1476-4660
• DOI: 10.1038/s41563-020-0789-2

Shape-memory polymeric materials lack long-range molecular order that enables more controlled and efficient actuation mechanisms. Here, we develop a hierarchical structured keratin-based system that has long-range molecular order and shape-memory properties in response to hydration. We explore the metastable reconfiguration of the keratin secondary structure, the transition from α-helix to β-sheet, as an actuation mechanism to design a high-strength shape-memory material that is biocompatible and processable through fibre spinning and three-dimensional (3D) printing. We extract keratin protofibrils from animal hair and subject them to shear stress to induce their self-organization into a nematic phase, which recapitulates the native hierarchical organization of the protein. This self-assembly process can be tuned to create materials with desired anisotropic structuring and responsiveness. Our combination of bottom-up assembly and top-down manufacturing allows for the scalable fabrication of strong and hierarchically structured shape-memory fibres and 3D-printed scaffolds with potential applications in bioengineering and smart textiles. Shear-aligned keratin protofibres are used to fabricate shape-memory fibres and three-dimensional scaffolds that respond to water.