3D-Printed High Strength Bioactive Supramolecular Polymer/Clay Nanocomposite Hydrogel Scaffold for Bone Regeneration

The emerging 3D bioprinting technique that is strongly dependent on the development of bioinks offers a promising opportunity to customize personalized bioscaffolds for precision and individualized therapy of bone defects. Hydrogels are one sort of attractive scaffolding materials due to their resemblance to extracellular matrices. Although much progress has been made in designing and fabricating high strength hydrogels, very few of them have been extended to the treatment of bone defects. In this work, we developed a hybrid bioink composed of a hydrogen bonding monomer (N-acryloyl glycinamide) (NAGA) and nanoclay. The hybrid ink could be conveniently tailored as a high strength PNAGA-Clay composite scaffold under UV light illumination of printed prehydrogel. The hydrogen bonding combined with physical cross-linking of nanoclay contributed to the superior mechanical performances as well as swelling stability of the hydrogels and bioscaffols. The sustainable release of intrinsic Mg²⁺ and Si⁴⁺ from the PNAGA-Clay scaffold was shown to promote the osteogenic differentiation of primary rat osteoblast (ROB) cells. Importantly, this implantable PNAGA-Clay scaffold highly efficiently facilitated the regeneration of new bone in tibia defects of rats. We anticipate that hybridization of the hydrogen bonding monomer with a variety of bioactive inorganic nanoparticles will offer new possibilities to develop numerous bioinks for 3D-printing of desired bioscaffolds to realize individualized repair of degenerated load-bearing tissues.