Strong, Self-Healing Gelatin Hydrogels Cross-Linked by Double Dynamic Covalent Chemistry

Hydrogels constructed from natural sources have received increased attention recently, including applications in biomedical fields. They are protein or polysaccharide cross-linked scaffolds that display water retention and are able to recognize host cargos. Their excellent biocompatibility does not always combine with high mechanical strength (up to 136 kPa) and thermostability, making them less useful in biomedical applications. This paper reports biocompatible gelatin hydrogels, double cross-linked via imine and Diels-Alder (DA) dynamic covalent frameworks. They showed integrated advantages of adjustable and durable mechanical strength, good thermal stability, biocompatibility for promoting cell growth and reasonable degradable rate. These hydrogels possess remarkable self-healing property, acid/alkali resistance at 65 °C and good integrity in organic solvents at 130 °C, holding great potential for biomedical applications in the areas such as cartilage regeneration, articular reconstruction or soft robotics.