Injectable\nSelf-Healing and Anti-Dissolving Low-Molecular-Weight\nHydrogels Enabled by Ionic Cross-Linking for Cell Encapsulation

Injectable behavior is often observed in polymer-based\nhydrogels\nyet is rarely achieved in low-molecular-weight hydrogels (LMWHs),\nthe realization of which may boost the development of new soft materials\nfor biomedical applications. Here, we report on injectable self-healing\nand antidissolving LMWHs that are formed through a simple ionic cross-linking\nstrategy, showing a fundamental application for the encapsulation\nof living cells. The LMWHs are formed by simply mixing Ca<sup>2+</sup> with negatively charged supramolecular polymers. Surprisingly, the\nresultant hydrogels are capable of rapidly self-healing within seconds\nafter damage, showing an unexpected injectable function. When the\nhydrogel is injected into an aqueous medium, continuous macroscopic\nhydrogel fibers can be produced. Interestingly, the hydrogel can remain\nintact in the aqueous medium, showing impressive antidissolving behavior\nwhich is less observed in other LMWHs. Furthermore, the hydrogel is\ndemonstrated to be nontoxic and can be used as a cytocompatible scaffold\nfor living cells. This work may open an avenue toward injectable and\nantidissolving LMWHs for the ever-expanding list of applications in\nbiotherapy and bioprinting.