Ultrafast Fabrication of Self-Healing and Injectable Carboxymethyl Chitosan Hydrogel Dressing for Wound Healing.

Herein, a new type of injectable carboxymethyl chitosan (CMCh) hydrogel wound dressing with self-healing properties is constructed. First, CMCh samples are homogeneously synthesized in alkali/urea aqueous solutions. Subsequently, trivalent metal ions of Fe3+ and Al3+ are introduced to form coordination bonds with CMCh, leading to an ultrafast gelation process. A series of hydrogels can be obtained by altering the concentration of CMCh and the relative content of metal ions. Owing to the dynamic and reversible characteristics of the coordination bonds, the hydrogel exhibits self-healing, self-adaption, and thermoresponsive ability. Moreover, due to the interaction between the amino groups on CMCh and SO42-, the hydrogel undergoes phase separation and can be painlessly detached from the skin with little residue. Taking advantage of all these characteristics, the hydrogel is used as a wound dressing and can significantly accelerate skin tissue regeneration and wound closure. This hydrogel has great potential in the application of tissue engineering.