Adaptable hydrogels with secondary reinforcement for regenerative medicine

While injectable hydrogels are able to be delivered in a minimally invasive way, they typically rely either on polymerization in situ, which is difficult to control in a surgical setting, or are designed to be shear-thinning, which results in mechanically weak gels with fast erosion rates. To address these limitations, we have designed several injectable double-network hydrogels that undergo two stages of crosslinking: the first stage provides cell protection during injection and rapid hydrogel self-healing, while the second stage reinforces the hydrogel in situ to minimize erosion and to provide a dynamic range of tunable mechanical properties. These novel, double-network hydrogels combine the advantages of traditional physical and covalent crosslinking and have a wide tuning range of storage moduli (~ 50 to 5,000 Pa below 5 wt% polymer). Several different types of crosslinking strategies and engineered biopolymers have been employed in these designs, which allows for customization for a variety of injectable, minimally invasive, regenerative medicine applications.