Performance optimization of injectable chitosan hydrogel by combining physical and chemical triple crosslinking structure.

To improve the biocompatibility and application properties of injectable chitosan hydrogel, an injectable triple crosslinking network hydrogel (CTGP) is prepared by physical interaction, Michael addition and disulfide bond formation based on thiolated chitosan (CS-TGA), β-glycerophosphate (β-GP) and poly(ethylene glycol) diacrylate (PEGDA) without the addition of cytotoxic crosslinkers and catalysts. Compared with the short gelation time of 2 min of CTG hydrogel (without PEGDA) at 37°C, CTGP hydrogel containing different molecular weight of PEGDA exhibits controllable gelation times from 1 to 22 min, which could meet the different demands in clinical application. Further, the compressive modulus is improved differently by introducing PEGDA into the system. The presence of PEGDA in CTGP hydrogel imparts better swelling property, and there is a sustained protein release from the hydrogel without any initial burst. In vitro cytotoxicity and hemolysis reveal that the gel is biocompatible. In vivo subdermal injection into mice models further confirms the non-cytotoxicity of the hydrogel and the hydrogel is highly resistant to degradation.