Rapid-Forming and Self-Healing Agarose-Based Hydrogels for Tissue Adhesives and Potential Wound Dressings.

To meet the progressive requirements of advanced engineering materials with superior physicochemical performances, self-healing and injectable hydrogels (AD hydrogels) based on agarose with pH-response were prepared through dynamic covalent Schiff-base linkages by simply mixing nontoxic agarose-ethylenediamine conjugate (AG-NH2) and dialdehyde-functionalized polyethylene glycol (DF-PEG) solutions. The self-healing and injectable capabilities of the hydrogels without any external stimulus are ascribed to dynamic covalent Schiff-base linkages between the aldehyde groups of DF-PEG and amine groups on AG-NH2 backbone. It is demonstrated that the AD hydrogels possess interconnected porous morphologies, rapid gelation time, excellent deformability, and good mechanical strength. The incorporated Schiff's base imparts the hydrogels to the remarkable tissue adhesiveness. In vivo hemostatic tests on rabbit liver demonstrate that the hydrogels are able to stanch the severe trauma effectively. Compared with the conventional gauze treatment, the total amount of bleeding sharply declined to be (0.19 ± 0.03) g, and hemostasis time was strikingly shorter than 10 s after treating with AD hydrogels. In summary, the self-healing ability, cytocompatibility, and adhesion characteristic of the pH-responsive hydrogels make them promising candidates for long-lived wound dressings in critical situations.