Amorphous Silk Fibroin Nanofiber Hydrogels with Enhanced Mechanical Properties.

Silk fibroin (SF) hydrogels have been engineered as universal substrates for various tissue regenerations and drug delivery. Although different physical and chemical crosslinking strategies are developed to form SF hydrogels with suitable performances, a significant gap remains to match specific requirements of various tissues. Here, amorphous SF nanofibers with more tyrosine residues outside the surfaces are used to replace traditional SF. Under the same crosslinking conditions, the use of amorphous SF nanofibers results in tougher properties, four times higher stiffness than that from traditional SF solutions. Unlike previous SF hydrogels, the SF nanofiber hydrogels show high tunability in wide modulus range of 0.6-160 kPa under low SF concentrations (below 5 wt%), showing improved mechanical match with various soft tissues. Better stability and cytocompatibility are also achieved, further confirming the superiority of the hydrogels as the tissue substrates. Therefore, a feasible strategy is developed to optimize the performances of SF hydrogel via tuning the nano-structural state in aqueous solutions, which will enrich SF-based hydrogel family in future.