Transiently malleable multi-healable hydrogel nanocomposites based on responsive boronic acid copolymers

The design of materials that mimic aspects of self-healing, as observed in nature, is of paramount importance as they could solve a number of problems in the biomedical field, such as the elimination of (bio-) material failure after prolonged use, improved integration at the interface with living tissues and more robust biomechanical performance. In this report, we propose the fabrication of soft hydrogels comprising a polymer matrix of poly(vinyl alcohol) mixed with a thermoresponsive boronic acid copolymer that is subsequently impregnated with poly(vinyl pyrrolidone) coated gold nanoparticles. The gels are crosslinked by the formation of reversible boronate ester bonds that can be remotely disrupted by a thermal or optical stimulus, endowing the gels with thermally-induced transient malleability that is optically trackable. It is demonstrated that the gels exhibit excellent healing properties within minutes even without the application of external stimuli. The rapid formation of the gels in concert with their fast and mild gel-sol phase transition under biologically relevant conditions is demonstrated by the encapsulation and release of cells in vitro. The proposed materials constitute a versatile cytocompatible platform for the construction of remotely healable soft gels for biomedical applications.