Injectable poly(ethylene glycol)/chitosan-based in situ hydrogel with wonderful mechanical property for wound dressing

To increase the water solubility of chitosan and enhance the mechanical strength of chitosan-based in-situ hydrogel, poly(ethylene glycol) monomethyl ether-grafted chitosan (PCS) was fabricated by a simple and efficient modification method with hexamethylene diisocyanate (HDI) as bridging agent, and then a series of poly(ethylene glycol)/chitosan-based in situ hydrogels (PCS@gel) were prepared from PCS and aldehyde-terminated poly(ethylene glycol) (DF-PEG) as cross-linking agent. The resultant PCS shows good water solubility in the absence of acid and its solid content is up to 8 wt%. By studying the effects of the mass ratio of PCS to DF-PEG and their solid content on the gel time and properties of PCS@gel, the results demonstrate that increasing the solid content of precursor solution can significantly shorten the gel time and improve its mechanical properties and adhesion strength. When the mass ratio of PCS to DF-PEG is 1:1, PCS@gel has a shorter gel time and higher mechanical strength. While the mass ratio of PCS to DF-PEG is 5:1, PCS@gel has better adhesion properties. Besides, PCS@gel also has good self-healing ability, antibacterial effect, low cytotoxicity and the ability to promote cell migration. Therefore, PCS@gel will have a promising application as a wound dressing.