Mechanically Reinforced Injectable Hydrogels

Injectable hydrogels have garnered significant research attention in biomedical applications due to their ability to be delivered to a target site via a minimally invasive route. However, given the inherent tension between injectability and strong mechanics in such hydrogels, the practical use of these materials is limited by the relatively weak mechanical properties typically achievable. In this spotlight article, we describe recent progress in developing approaches for the mechanical reinforcement of injectable hydrogels via three major strategies: manipulating gel concentration/functionalization, using a double/ interpenetrating network structure, and incorporating nanoparticle/nanofiber reinforcing agents into the gel matrix. We particularly highlight our work on using chemically orthogonal in situ-gelling reactive pairs and cellulose nanocrystals as anisotropic nanoparticle reinforcing agents to develop injectable hydrogels with significant mechanical enhancement, improved shear thinning, and in situ-generated anisotropic properties.