Abstract

Double-network (DN) hydrogels have been confirmed to possess versatile mechanical properties. Herein, we fabricated a stretchable, tough, and self-recoverable DN hydrogel containing a physically cross-linked carboxymethylated curdlan (CMCD) network and a covalently cross-linked polyacrylamide (PAAm) network. The coupled hydrogen bonding and ionic associations of CMCD macromolecules as a sacrificial architecture endowed the CMCD/PAAm DN hydrogel with tunable, multiple, and recoverable mechanical properties within a large scope. The CMCD microcrystal network was transformed into a homogeneous structure via osmotic stress. The resulting DN hydrogel exhibited stretchable and tough mechanical properties with a tensile strength of 0.69 MPa and an elongation at a break of 2185% at a high water content of approximately 75%. The hydrogel was evaluated through in vitro cell experiments, including cytotoxicity evaluation, live/dead fluorescence microscopy, flow cytometry analysis, and in vivo cartilage repair. Our results show that the DN hydrogel manifests its competence for growth-factor-free cartilage repair and has great potential as a scaffold for cartilage repair.