Shear thinning pectin hydrogels physically cross-linked with chitosan nanogels.

The development of a polymer-nanogel hydrogel based on a pair of polysaccharides is reported for the first time. This new hydrogel exhibits self-healing properties due to physical interactions between soluble pectin chains and chitosan nanogels. The nanogels act as crosslinking agents between pectin chains, leading to the formation of thermos-responsive hydrogel. Due to the dynamic interactions between the chains and the nanogels, the formed network dissociate under applied shear, allowing the hydrogel to flow. Moreover, elimination of the applied shear results in exceptionally fast and comprehensive recovery of the storage modulus, reverting the mixture back into solid form. The viscosity and Young modulus increased with the nanogels concentration while the equilibrium swelling decreased as the nanogels concentration increased suggesting a direct relation between the cross-linking degree and nanogel content. This novel hydrogel displays network recovery suitable for injectable biomedical applications, while benefiting from the advantages of nanogels as carriers.