3D-printable self-healing and mechanically reinforced hydrogels with host–guest non-covalent interactions integrated into covalently linked networks

) and acryloylated tetra-ethylene glycol-modified adamantane (A-TEG-Ad). Subsequently, a host-guest supramolecular hydrogel (HGGelMA) was obtained through copolymerization between the arms of HGSM and gelatin methacryloyl (GelMA) to form a covalently crosslinked network. The HGGelMA was robust, fatigue resistant, reproducible and rapidly self-healing. In HGGelMA, the covalent crosslinking maintained its overall shape whereas the weak reversible non-covalent host-guest interactions reinforced its mechanical properties and enabled it to rapidly self-heal upon fracturing. The reversible non-covalent interactions could be re-established upon breaking, so as to heal the hydrogel and dissipate energy to prevent catastrophic fracture propagation. Furthermore, the precursors of the HGGelMA were sufficiently viscous and could be rapidly photocrosslinked to produce a robust scaffold with an exquisite internal structure through 3D printing. The 3D-printed HGGelMA hydrogel scaffold was biocompatible, promoted cell adhesion and proliferation, and supported tissue in-growth. Our strategy of integrating non-covalently linked HGSM in a covalently linked hydrogel network represents a new approach to the development of natural polymers into biocompatible hydrogels with improved strength as well as desired self-healing and 3D-printability.