Self-Healing Injectable Polymer Hydrogel via Dynamic Thiol-Alkynone Double Addition Crosslinks

Introduction of dynamic thiol-alkynone double addition crosslinks in a polymer network enable the formation of a self-healing injectable polymer hydrogel. A 4-arm polyethylene glycol (PEG) tetra-thiol star polymer is crosslinked by a small molecule alkynone via the thiol-alkynone double adduct, to generate a hydrogel network under ambient aqueous conditions (buffer pH=7.4 or 8.2, room temperature). The mechanical properties of these hydrogels can be easily tuned by varying the concentration of polymer precursors. Through the dynamic thiol-alkynone double addition crosslink, these hydrogels are self-healing and shear thinning, as demonstrated by rheological measurements, macroscopic self-healing and injection tests. These hydrogels can be injected through a 20G syringe needle and recover after extrusion. In addition, good cytocompatibility of these hydrogels is confirmed by cytotoxicity test. This work shows the application of a new type of dynamic covalent chemistry in the straightforward preparation of self-healing injectable hydrogels, which may find future biomedical applications such as tissue engineering and drug delivery.