Strong and Tough Microgel-Reinforced Hydrogels Through Reversible Metal-Ligand Interaction

Bulk hydrogels have gained attention over the past few years especially in the biomedical field due their high degree of biocompatibility and high water content. Indeed, polysaccharides as Cellulose and its functionalized derivatives, play a fundamental role in the synthesis of nature inspired hydrogels due to their intrinsic biocompatibility and large availability from a great abundance of natural sources. Unfortunately, the poor mechanical properties and poor injectability have restricted their application for repair and replacement of tissues with an elastic modulus lower than 1MPa (“Soft Tissues”). Microgels in jammed state own by their very nature the property of “shear thinning”, key requirements for extrudability, making them a perfect candidate for the application in additive manufacturing and so overcoming the hurdles of the non-injectable bulk ones. Reinforcing microgels with the infiltration by a second hydrogel network and the addition of a further crosslinking degree with the metal ligand coordination, allowed to overcome this issue. Indeed, hydrogels with outstanding mechanical properties, being able to sustain few MPa of mechanical stress applied, have been obtained. These results and the versatility of jammed microgels as ink in the 3D Bioprinting field, would enhance the possibility for the fabrication of hydrogels-based patient specific load bearing scaffolds.