Study On Preparation And Application Performance Of Eucommia Ulmoides Rubber And Hydrogel Composite Wound Dressing

In daily life,burns,friction,scratches,and other injuries can damage the integrity of the skin and form wounds.Once not properly cared for,wounds can easily develop into chronic wounds,and in severe cases,they can even threaten life.Wound dressings are essential medical materials in the process of wound management.The commonly used wound dressings in clinical practice,such as gauze,bandages,etc.,belong to dry dressings.When used,the dry surface of the wound can easily adhere to the wound,resulting in secondary injury to the wound during replacement and burden on patients.With the gradual maturity of the"wet healing theory",the research and development of moist wound dressings is urgent.Sodium alginate is a common natural polymer polysaccharide,which is cheap,safe,non-toxic and has good biocompatibility;At the same time,the excellent hemostasis of sodium alginate has shown great potential in the field of wound healing.In addition,Eucommia ulmoides rubber is a natural polymer rubber extracted from Eucommia ulmoides tissue,which has good film-forming properties;Eucommia ulmoides rubber film has excellent flexibility and water vapor barrier properties.When used in wound dressings,it can not only prevent the loss of water at the wound site,but also meet the treatment needs of special wounds（joints,etc.）.Chlorogenic acid is an active component of traditional Chinese medicine with good antibacterial activity.Adding chlorogenic acid to wound dressings can effectively reduce the risk of infection by microorganisms such as bacteria.This project designs a composite wound dressing that combines a drug layer with a substrate layer.First,sodium alginate was sulfonated,quaternized and treated with compound chlorogenic acid,and the gel solution obtained was used as the drug layer of the composite wound dressing;Characterize and test its morphology,structure,Zeta potential,swelling performance,rheological properties,and cytotoxicity.Secondly,a simple solution casting method is used to obtain a uniform Eucommia ulmoides rubber film as the base layer of the composite wound dressing.The two are physically combined to obtain antibacterial composite wound dressing;The mechanical properties,water vapor barrier properties,drug release behavior and antibacterial properties of the dressing were studied.The therapeutic effect of the composite wound dressing on the wound was evaluated through animal experiments,and the healing mechanism was further explored by means of histopathology and immunohistochemistry.The main results achieved are as follows:1.Preparation of sulfonated sodium alginate（SSA）,quaternized sodium alginate（QSA）and chlorogenic acid complex sodium alginate（CGA-SA）by chemical and physical methods.The introduction of new functional groups in SSA and QSA resulted in significant changes in their surface morphology,while the morphology of CGA-SA was relatively similar to that of SA,except for a change in pore size,which decreased from 50-150μm to5-15μm;Compared with SA,the Zeta potential of SSA,QSA,and CGA-SA decreased to-9.4 m V,-21.8 m V,and-32.2 m V,respectively.The cytotoxicity test results indicate that SSA,QSA,and CGA-SA all meet the toxicity level I standard,and used as composite dressings has certain biological safety and feasibility.2.Design SSA/EUR,QSA/EUR,and CGA-SA/EUR composite wound dressings by combining the drug layer with the substrate layer.Composite wound dressings have high tensile stress（10.81-12.55 MPa）,high Young’s modulus（39.82-68.01 MPa）,and high elongation at break（253.13%-313.74%）;All composite wound dressings have lower WVP values and are dependent on relative humidity.At high relative humidity（RH=76%）,CGA-SA/EUR wound dressings have the highest WVP value,only 0.39×10^-7g/m/h/Pa;The drug release behavior of wound dressings was determined using the Korsmeyer-Peppas model,and the cumulative drug release amount depends on the p H value of the medium;SSA/EUR wound dressing has obvious inhibitory effect on E.coli and S.aureus（the diameter of the inhibitory ring is 19 mm and 16 mm respectively）,while QSA/EUR and CGA-SA/EUR wound dressing have the same antibacterial effect on Staphylococcus aureus（the diameter of the inhibitory ring is 15 mm）,but have no obvious inhibitory effect on Escherichia coli.Overall,composite wound dressings have strong mechanical properties,good water vapor barrier properties,high cumulative drug release,and excellent antibacterial properties.3.Evaluate the potential application of composite wound dressings using a mouse full skin wound model.Compared with the control group,composite wound dressings can accelerate wound healing.Especially,the CGA-SA/EUR composite wound dressing has the best therapeutic effect,with a wound healing rate of 98%after 11 days of treatment,better than commercially available dressings.The results of histopathology and immunohistochemical analysis showed that the composite wound dressing could promote the wound healing process by promoting the formation of granulation tissue,the deposition of collagen fibers and the formation of early new blood vessels.