| Tissue damage is one of the factors that affect the quality of life.However,traditional ligand transplantation treatment strategies are limited by the source of the ligand,low matching,immune response.Hydrogels with a three-dimensional network structure are used in tissue engineering and make them promising tissue repair materials.However,conventional hydrogels do not have dynamic reversibility properties,so they cannot restore their structures and performances after injury,and thus lose their proper functions.Therefore,hydrogels with self-healing properties have been developed to solve this shortcoming.The main work of this thesis is to use hyaluronic acid as the raw material and construct a hydrogel network by reversible imine bonds/acylhydrazone bonds,in order to obtain a fast self-healing and injectable hyaluronic acid self-healing hydrogel.Hence,this work followed from the next three aspects:(1)Aldehyde hyaluronic acid(AHA)/Cystamine hydrochloride(Cys)hydrogel system.In an acidic environment,the AHA/Cys hydrogel system was prepared through the imine cross-linking of AHA and Cys.Due to the introduction of dynamic reversible imine bonds,this hydrogel has p H responsiveness and self-healing properties.At room temperature,the hydrogel could achieve a 100% healing efficiency within 10 minutes.This rapid self-healing property also allowed the hydrogel network to quickly reorganize after being destroyed.However,the weak cross-linking method also caused the hydrogel to be not stable enough,and it would be hydrolyzed quickly in the PBS7.4 aqueous solution,which will affect its application.(2)Aldehyde hyaluronic acid(AHA)/3,3’-dithiobis(propionylhydrazide)(DTP)hydrogel system.The AHA/DTP hydrogel was prepared by condensation of the hydrazide group of DTP and the aldehyde group of AHA.The hydrogel was formed within 20 s,which made it possible to implant the hydrogel in the body.The presence of acylhydrazone bonds and disulfide bonds also made hydrogels have rapid selfhealing properties(100% healing within 30 min at 25°C)and multiple responsiveness(p H and redox responsiveness).In addition,the stability of the hydrogel had also been improved,and it could exist stably for more than 10 days in a PBS 7.4 aqueous solution.At the same time,the hydrogel also showed good cytocompatibility to mouse fibroblasts(L929)and mouse neural stem cells(NE-4C).(3)Aldehydated hyaluronic acid(AHA)/hydrazide hyaluronic acid(DHA)hydrogel system.Using hyaluronic acid as raw material,it was modified by aldehyde and hydrazide to obtain AHA and DHA,and AHA/DHA was prepared by using different ratios of hydrazide group and aldehyde group.Under the influence of acylhydrazone bonds and disulfide bonds,the hydrogel could achieve a 100% healing efficiency within60 minutes in an environment of 25°C,and exhibits sensitivity to p H and redox.The hydrogel was also more stable in PBS 7.4 aqueous solution and could exist stably for at least 20 days.In addition,the culture of L929 and NE-4C cells also showed good cell compatibility of the hydrogel.In short,a multiple dynamic covalent bond strategy based on the "Schiff" reaction was used to prepare rapid self-healing hydrogels.Hydrogels have high-efficiency selfhealing properties,good cell compatibility,multiple responsiveness and injectability,and are expected to be widely used in biomedical fields such as drug release,wound hemostasis,soft robots,and nerve repair. |
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