Self-healing and injectable chitosan/konjac glucomannan hydrogel with pH response for controlled protein release.

Dynamic hydrogels with the features of injection, self-healing, and remodeling at the target site have been developed as smart multifunctional biomaterials for drug delivery. However, most self-healing injectable hydrogels are difficult to control protein release after implantation, owing to the deficiency of pH responsiveness, which reduces the bioavailability of proteins. Herein, we propose a facile strategy to endow pH responsiveness into a dynamic hydrogel with both self-healing and injectable capabilities, by crosslinking biomacromolecular backbones via dual pH sensitive dynamic covalent bond. Particularly, oxidized konjac glucomannan (OKGM) can be crosslinked with poly (aspartic hydrazide) (PAHy) and N-carboxyethyl chitosan (CEC) to form dynamic acylhydrazone bonds and imide bonds, respectively, endowing the hydrogel with pH responsiveness and dynamic behaviors. Specifically, PAHy facilitates the formation of acylhydrazone bonds, improving the mechanical properties and pH sensitivity while reducing the degradation behavior of the hydrogels under physiological conditions. Kinetics indicate that the release of bovine serum albumin follows Fick diffusion under different pH conditions. The pH responsive hydrogel with self-healing injectable capabilities has the potential to be used as a controllable and sustain release carrier for protein drugs.