Highly Tough, Stretchable, and Enzymatically Degradable\nHydrogels Modulated by Bioinspired Hydrophobic β‑Sheet\nPeptides

Abstract

Peptide-based\nsupramolecular hydrogels have attracted great attention\ndue to their good biocompatibility and biodegradability and have become\npromising candidates for biomedical applications. The bottom-up self-assembly\nendows the peptides with a highly ordered secondary structure, which\nhas proven to be an effective strategy to improve the mechanical properties\nof hydrogels through strong physical interactions and energy dissipation.\nInspired by the excellent mechanical properties of spider-silk, which\ncan be attributed to the rich β-sheet crystal formation by the\nhydrophobic peptide fragment, a hydrophobic peptide (HP) that can\nform a β-sheet assembly was designed and introduced into a poly­(vinyl\nalcohol) (PVA) scaffold to improve mechanical properties of hydrogels\nby the cooperative intermolecular physical interactions. Compared\nwith hydrogels without peptide grafting (P-HP0), the strong β-sheet\nself-assembly domain endows the hybrid hydrogels (P-HP20, P-HP29,\nand P-HP37) with high strength and toughness. The fracture tensile\nstrength increased from 0.3 to 2.1 MPa (7 times), the toughness increased\nfrom 0.4 to 21.6 MJ m^–3 (54 times), and the compressive\nstrength increased from 0.33 to 10.43 MPa (31 times) at 75% strain.\nMoreover, the hybrid hydrogels are enzymatically degradable due to\nthe dominant contribution of the β-sheet assembly for network\ncross-linking. Combining the good biocompatibility and sustained drug\nrelease of the constructed hydrogels, this hydrophobic β-sheet\npeptide represents a promising candidate for the rational design of\nhydrogels for biomedical applications.