Preparation Of In Situ Crosslinked Hyaluronic Acid Composite Hydrogel And Its Application In Skin Wound Repair

Objective:（1）Hyaluronic acid（HA）was modified to prepare acylhydrazide functionalized HA.Then,tetrachloroauric acid（HAu Cl₄）was reduced in situ by acylhydrazide functionalized HA to form Au NPs,to prepare in-situ crosslinked HA composite hydrogel with injectability,3D printability and photothermal effect.（2）Explore and evaluate the functionality of HA composite hydrogels.Methods:（1）Three different types of acylhydrazide functionalized HA were prepared by esterification of hydrazide monomers with HA.Then,the three different types of acylhydrazide functionalized HA were mixed with HAu Cl₄ to prepare different types of in-situ cross-linked HA composite hydrogels.The structure of the prepared products was analyzed by nuclear magnetic hydrogen spectroscopy and infrared spectroscopy,and the substitution rate of acylhydrazide functionalized HA was detected by TNBS UV-vis spectroscopy.The micro-morphology,swelling ratio and elastic modulus of the hydrogel were characterized by scanning electron microscope,gravimetric method and mechanical testing machine,respectively.（2）The injection method,3D printing technology and real-time temperature detection under near-infrared excitation were used to explore the injectability,3D printing and photothermal properties of the HA composite hydrogels.（3）The cytotoxicity of HA compound hydrogels was detected by CCK8 method,and the effects of HA composite hydrogels combined with photothermal therapy on skin wound healing and wound healing characteristics were explored through mouse skin wound models and HE staining..Results:（1）Three different types of hydrazide functionalized HA（i.e.HA-C,HA-An and HA-D）were successfully prepared,with an average substitution rate of 9.5%.HA-C,HA-A and HA-D were mixed with HAu Cl₄ in the form of solution to form in-situ crosslinked hydrogels;among them,in HA-C/Au hydrogel and HA-A/Au hydrogel,HAu Cl₄ was reduced to AuNPs,in situ,while the mixture of HA-D and HAu Cl₄ gelled but did not show the formation of Au NPs;the mixture of unmodified HA and HAu Cl₄ did not gelate and did not show the formation of Au NPs.Three kinds of HA composite hydrogels had interpenetrating network structure,adjustable swelling properties and certain elastic modulus.（2）Three kinds of HA composite hydrogels had injectability and3D printability.The HA composite hydrogel formed in situ Au NPs had high photothermal conversion efficiency.（3）The results of CCK8 showed that three kinds of HA composite hydrogels had good biocompatibility.Animal experiments showed that HA combined with hydrogel combined with photothermal therapy could significantly promote the repair of skin trauma and reduce the inflammatory response of skin trauma tissue.Conclusion:（1）The in-situ cross-linked HA composite hydrogels with injectability,3D printing and high-efficiency photothermal effect were successfully prepared in a gentle manner.（2）HA compound hydrogels as a wound dressing combined with photothermal therapy can significantly reduce the inflammatory response of skin wound tissues and promote the repair of skin wounds..