Design, Fabrication, and Function of Silk-Based Nanomaterials

Animal silks, consisting of pure protein components, offer an extraordinary combination of strength, elongation, and toughness, exceeding most engineered materials. The secret to this success is their unique nanoarchitectures formed through the hierarchical self-assembly of silk proteins. This natural process contrasts the production of artificial silk materials, which usually are directly constructed as bulk structures from silk fibroin (SF) molecules. A variety of fabrication strategies to control nanostructures of silks or to create functional materials from silk nanoscale building blocks have been developed in the recent years. These emerging fabrication strategies offer an opportunity to tailor the structure of SF at the nanoscale and provide a promising route to produce structurally and functionally optimized silk nanomaterials. Herein, the critical roles of silk nanoarchitectures in property and function of natural silk fibers are reviewed and the strategies of utilization of these silk nanobuilding blocks are outlined. Further, the state-of-the-art techniques to create silk nanoarchitectures and to generate silk-based nanocomponents are summarized. An effective approach to constructing sophisticated silk functional nanocomposites with promising applications in regenerative medicine, drug delivery, and optical and electronic device designs is provided. Further, such insights suggest templates to consider for other material systems.