Programing Performance of Silk Fibroin Superstrong Scaffolds by Mesoscopic Regulation among Hierarchical Structures.

To design higher-strength natural scaffold materials, wool keratin (WK) rich in α-helix structures is used as a well-defined foreign substrate, which induces the formation of β-crystallites in silk fibroin (SF). Consequently, the macroscopic properties of silk materials (such as the rheological properties of SF hydrogels and the mechanical properties of stents) can be manipulated by governing the change in the hierarchical mesoscopic structure of silk materials. In this work, by monitoring the structure and morphology in the SF gel process, the mechanism of the effect of keratin on SF network formation was speculated, which was further used to design ultra-high-strength protein scaffolds. It has been confirmed that WK accelerates the gelation of SF by reducing the multistep nucleation barrier and increasing the primary nucleation sites, and then establishing a high-density SF domain network. The modulus of the protein composite scaffold prepared by this facile strategy can reach 11.55 MPa, and the MC-3T3 cells can grow well on the scaffold surface. The results suggest that freeze-dried biocompatible SF-based scaffolds are potential candidates for bone tissue engineering.