Physically cross-linked gellan gum/hydrophobically associated polyacrylamide double network hydrogel for cartilage repair

Biopolymer hydrogels have attracted much attention as scaffolds for tissue engineering owing to the unique physical features analogous to native extracellular matrices. However, the poor mechanical property and fast degradation greatly limit their application in cartilage repair. Herein, a robust physically cross-linked gellan gum/hydrophobically associated polyacrylamide double network hydrogel is developed. Benefitting from the synergistic energy dissipation mechanism, the resultant hydrogel exhibits outstanding mechanical properties, which is comparable with native cartilage. Moreover, the physically cross-linked double network hydrogel displays excellent anti-fatigue, wear resistant, self-healing, and stability in the physiological environment. Owing to the feature of natural biopolymer and the absence of toxic chemical cross-linking agents, the double network hydrogel demonstrates excellent biocompatibility and can promote the adhesion and proliferation of chondrocytes. Based on the comparable mechanical performance and excellent biocompatibility, the hydrogel is explored as cartilage substitute for the repair of damaged cartilage. The in vivo evaluation in a cartilage defect rabbit model indicates that the hydrogel can serve as a growth-factor-free scaffold to promote the repair of cartilage defect. This study shows the potential of a robust biopolymer hydrogel for cartilage regeneration.