A Self‐Thickening and Self‐Strengthening Strategy for 3D Printing High‐Strength and Antiswelling Supramolecular Polymer Hydrogels as Meniscus Substitutes

Abstract 3D printing of high‐strength and antiswelling hydrogel‐based load‐bearing soft tissue scaffolds with similar geometric shape to natural tissues remains a great challenge owing to insurmountable trade‐off between strength and printability. Herein, capitalizing on the concentration‐dependent H‐bonding‐strengthened mechanism of supramolecular poly( N ‐acryloyl glycinamide) (PNAGA) hydrogel, a self‐thickening and self‐strengthening strategy, that is, loading the concentrated NAGA monomer into the thermoreversible low‐strength PNAGA hydrogel is proposed to directly 3D printing latently H‐bonding‐reinforced hydrogels. The low‐strength PNAGA serves to thicken the concentrated NAGA monomer, affording an appropriate viscosity for thermal‐assisted extrusion 3D printing of soft PNAGA hydrogels bearing NAGA monomer and initiator, which are further polymerized to eventually generate high‐strength and antiswelling hydrogels, due to the reconstruction of strong H‐bonding interactions from postcompensatory PNAGA. Diverse polymer hydrogels can be printed with self‐thickened corresponding monomer inks. Further, the self‐thickened high‐strength PNAGA hydrogel is printed into a meniscus, which is implanted in rabbit's knee as a substitute with in vivo outcome showing an appealing ability to efficiently alleviate the cartilage surface wear. The self‐thickening strategy is applicable to directly printing a variety of polymer‐hydrogel‐based tissue engineering scaffolds without sacrificing mechanical strength, thus circumventing problems of printing high‐strength hydrogels and facilitating their application scope.