| In the clinical treatment of damaged skin,the traditional way is to use gauze,bandage and other dry dressings to wrap it,in order to stop bleeding,prevent wound infection,and promote wound healing.However,traditional dressings cannot provide a moist environment for the wound to promote cell proliferation.At the same time,dry dressings tend to stick to the wound,resulting in secondary injury of the wound surface during dressing replacement and ultimately delaying the healing process.In recent years,hydrogel as a new dressing plays a positive role in promoting wound healing.Hydrogel material is simple to synthesize.It could provide a structure similar to extracellular matrix and provide a wet environment for wound healing.It is convenient to load drugs in the synthesis process and it is easy to be promoted in clinical.To sum up,hydrogel is an ideal wound dressing.In this study,chitosan,protocatechuic acid,hyaluronic acid was as the raw materials to prepare a hydrogel dressing.The hydrogel dressing loaded zinc oxide nano particles and graphene,for enhancing antibacterial ability.The hydrogel had excellent biocompatibility,adhesion performance,cell proliferation,antibacterial ability and anti-inflammatory effect.The main study of this paper is as follows:（1）Zinc oxide nano particles and graphene oxide were prepared.The antibacterial ability and sterilization mechanism of zinc oxide nano particles and graphene oxide against Staphylococcus aureus and Escherichia coli were studied.The results showed that the concentration of zinc oxide nano particles and graphene oxide was at 1.0mg·m L-1 and 0.5 mg·m L-1 respectively had good antibacterial performance against the two kinds of bacteria.The zinc oxide nano particles attached to the surface of the bacteria,released zinc ions and killed them by destroying the surface of bacteria.Graphene oxide physically destroyed the envelope of bacteria and caused them to rupture.（2）In order to improve the solubility of chitosan in water,chitosan was modified into N-Succinyl chitosan.Protocatechuic acid was grafted onto the amino group of chitosan at C-2 position in order to improve the adhesion and antibacterial performance.Hyaluronic acid was oxidized with sodium periodate to give it a dialdehyde structure.The aldehyde group of oxidized hyaluronic acid and the amino group of modified chitosan reacted with Schiff base to produce hydrogel dressings with good moisture retention,strong adhesion and biocompatibility.Meanwhile,in order to prevent wound infection,zinc oxide nano particles composite graphene oxide was introduced into the hydrogel system to prepare composite hydrogel dressing.The results showed that hydrogels had continuous and stable three-dimensional network structure,short gel time,excellent hydrophilicity and low hemolysis.The hydrogel had low cytotoxicity at low doping level of zinc oxide nano particles composite graphene oxide.（3）A total wound resection model of Sprague Dawley male rats was established.Animal experiments were carried out using the self-made wound dressing and commercial chitosan dressing.The advantages and defects of each material were evaluated by observing the wound morphology and calculating the wound healing rate.Hematoxylin and eosin staining and Masson staining were used to observe the number of inflammatory cells,gland growth,wound epithelialization,collagen fiber growth and muscle fiber growth of damaged tissues from a microscopic perspective.The results showed that the composite hydrogel had the best healing effect on the wound,and the wound healed completely 14 days after the establishment of the wound without obvious scar. |
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