Fabrication and Mechanical Properties of Engineered Protein‐Based Adhesives and Fibers

Protein‐based structural biomaterials are of great interest for various applications because the sequence flexibility within the proteins may result in their improved mechanical and structural integrity and tunability. As the two representative examples, protein‐based adhesives and fibers have attracted tremendous attention. The typical protein adhesives, which are secreted by mussels, sandcastle worms, barnacles, and caddisfly larvae, exhibit robust underwater adhesion performance. In order to mimic the adhesion performance of these marine organisms, two main biological adhesives are presented, including genetically engineered protein‐based adhesives and biomimetic chemically synthetized adhesives. Moreover, various protein‐based fibers inspired by spider and silkworm proteins, collagen, elastin, and resilin are studied extensively. The achievements in synthesis and fabrication of structural biomaterials by DNA recombinant technology and chemical regeneration certainly will accelerate the explorations and applications of protein‐based adhesives and fibers in wound healing, tissue regeneration, drug delivery, biosensors, and other high‐tech applications. However, the mechanical properties of the biological structural materials still do not match those of natural systems. More efforts need to be devoted to the study of the interplay of the protein structure, cohesion and adhesion effects, fiber processing, and mechanical performance. Recent progress on the design and mechanical investigation of engineered protein‐based biomaterials is reviewed. As the two representative examples, the main discussion is of proteinaceous adhesives and fibers. The hierarchical structures of proteins have a great influence on the mechanical properties of relevant biomaterials. Perspectives and challenges in the field of functional proteins are also presented.