Preparation And Properties Of Hydrogel Hybrid Dressing For Diabetic Wound Repair

Diabetes is one of the largest chronic diseases in the world,which seriously endangers human health.The main reason why diabetes wounds are difficult to heal is that diabetes ulcers often occur in the foot,which is prone to lower limb vascular lesions,resulting in poor angiogenesis and insufficient blood supply to the foot wounds.In addition,factors such as hyperglycemia,infection,long-term inflammation and hypoxia are also important factors affecting wound healing of diabetes.These factors cause diabetic wounds to take longer to heal than normal wounds,even lead to amputation.In view of these factors,designing and preparing wound dressings to promote diabetic wound healing remains a great challenge.Hydrogels have become good candidates for wound dressings with its good hygroscopicity and biocompatibility.Compared with traditional dressings,hydrogels are beneficial to hemostasis,and can also provide a physical barrier for microbial infection,keep the environment moist,ensure the penetration of oxygen,and meet the physiological environment requirements for wound healing.More importantly,the nanomaterials can be stably dispersed in the porous network structure of the hydrogel to achieve antibacterial and oxygen production properties.Therefore,based on the above requirements,a multifunctional hydrogel composite dressing was prepared to promote wound repair in diabetes.The research work of this paper mainly includes the following aspects:Bacterial infections and hypoxia must be addressed in chronic wounds.In the present study,degradable hydrogel dressings were prepared by dextran macromers,and then polydopamine（PDA）nanoparticles and manganese dioxide（MnO₂）nanoparticles were introduced to endow the hydrogel dressings with antibacterial properties and oxygenation performance.The scanning electron microscopy（SEM）was used to explored the porous structure of hydrogel,and the nanoparticles were well dispersed in the hydrogel could be seen from the electron microscope picture.The biodegradation properties of the hydrogels were characterized by SEM and weight loss test,and the results showed that the dextran hydrogels prepared were prepared in this study owed good enzymatic degradation performance.The photothermal performance results demonstrated that PDA nanoparticles owed excellent photothermal conversion efficiency,which could trigger photothermal therapy to kill bacteria and remove bacterial biofilms.In addition,MnO₂ nanoparticles catalyzed endogenous hydrogen peroxide（H₂O₂）to generate oxygen（O₂,16 mg/L）.A diabetic wound model was used to demonstrate that the degradable hydrogel with photothermal effect could effectively promote wound healing within 14 days.In diabetic wounds,high blood sugar levels not only hinder wound healing,but also facilitate the aggregation and growth of bacteria to form bacterial biofilms.Furthermore,diabetic ulcers mostly occur on the feet,which bear the full weight of the human body and a lot of exercise demands.Local movement can easily tear the foot wound and cause the dressing to fall off after trauma.In this study,an antibacterial adhesive hydrogel dressing with hypoglycemic effect was prepared.Polydopamine/acrylamide（PDA/AM）hydrogels with adhesion properties were prepared.And then Glucose oxidase（GOx）and MnO₂ nanoparticles were added to the PDA/AM hydrogel to promote wound repair in diabetes.The hydrogel had a uniform porous structure and excellent swelling properties.GOx reduced hyperglycemia to normal levels and prevented over-oxidation of catechols.The compression test and adhesion test showed that the compressive strength of the hydrogel was 55 k Pa,which could bear foot pressure;the adhesion strength was 32.69 k Pa,which could be tightly attached to the wound to prevent falling off.The photothermal conversion efficiency of MnO₂ nanoparticles was 66.1%.Antibacterial experiments results showed that under near-infrared 808 nm irradiation after 10 min,the bactericidal efficiency of E.coli and S.aureus were 97.87%and 99.99%,respectively,and the biofilm was completely eliminated.In addition,the H₂O₂ produced by the decomposition of glucose under the catalysis of GOx,which could generate oxygen by the catalysis of MnO₂.In vitro hemostasis tests and in vivo mouse liver hemorrhage experiments demonstrated that the multifunctional hydrogel possessed excellent blood cell and platelet adhesion properties,it could stop bleeding rapidly and effectively.A mouse diabetic wound model was used to evaluate the promoting effect of multifunctional hydrogel on wound healing and angiogenesis,and the results showed that the multifunctional hydrogels could produce abundant oxygen,promote angiogenesis and accelerate the healing of diabetes wounds.Frequent replacement of wound dressings at the wound can easily lead to tearing of the wound and secondary injury of the wound tissue.Therefore,wound dressings are urgent to be prepared to promote the repairing and monitoring of chronic diabetic wounds in real time.Herein,multifunctional conductive hydrogel dressings were prepared based on cascade reactions in this study.Besides,the addition of aluminum ions endowed the hydrogel dressing with excellent electrical conductivity（3.2 S/m）.The results showed that the hydrogel dressing owed excellent compressive properties and adhesion properties.Under the action of GOx and catalase（CAT）,it could effectively reduce blood glucose level and generate abundant oxygen to promote angiogenesis.At the same time,the hydrogels prepared in this study had outstanding antibacterial properties and cell compatibility.Because of the excellent adhesion properties,the prepared hydrogel could firmly attach to the wound,and it is also easy to adhere to other objects,which may cause tearing and infection of the wound.Therefore,this study further optimized the wound dressing by compounding the non-woven fabric and the hydrogel to prepare the hydrogel/non-woven composite dressing.The tests showed that the hydrogel/non-woven composite dressing had good moisture absorption and compression properties,and could effectively kill bacteria and promote L929 cell growth and proliferation.In addition,3D hydrogel/non-woven sensor array could be assembled by multiple hydrogels according to the size of the wound,which could be applied to monitor the wound healing of diabetes foot in real time.In summary,the multifunctional hydrogel/non-woven composite dressing possessed the functions of hemostasis,antibacterial,hyperglycemia control and oxygen generation to accelerate the repairing of diabetic wounds,it could also own the advantages of simple and convenient operation,which could accurately detect the degree of wound healing,and had broad application prospects in the field of diabetic chronic wound repair.