Preparation And Performance Study Of Uran Grass Extract/polyvinyl Alcohol Medical Dressing

Skin is the first line of defense for the human body and the environment,which has the function of resisting external bacterial infections and maintaining normal cell growth.The skin needs a medical dressing to protect the wound after it is damaged.Medical dressings maintain antibacterial environment through antibacterial agents and promote healing of skin wounds.Natural antibacterial agents used in medical dressings can overcome the defects of bacterial resistance caused by inorganic antibacterial agents.The safety of organic antibacterial agents is still being studied.Therefore,natural antibacterial agents have become the first choice for trauma medicine.Luteolin in Carex meyeriana Kunth extract has excellent antibacterial properties.It is made into a film shape and is used in the medical field.This breaks through the difficulty that Carex meyeriana Kunth was only used in the low-end and coarse products such as insoles,Sandals.And it broadens the application of Carex meyeriana Kunth.In this paper,the antibacterial Carex meyeriana Kunth extract/polyvinyl alcohol medical dressing was prepared by electrostatic spinning.Firstly,the Carex meyeriana Kunth extract was prepared by hydrothermal method and its antibacterial performance was studied.Then the extract is blended with polyvinyl alcohol for electrospinning.The effects of spinning solution concentration,spinning voltage,and spinning distance on the morphology of nanofibers are investigated.And it obtained the best process by response surface method;Due to the existence of a large number of hydrophilic groups in polyvinyl alcohol,the nanofiber film dressing was modified by glutaraldehyde gas-phase.This improves the water resistance of the film.The specific conclusions are as follows:(1)The solutions of Carex meyeriana Kunth extract are prepared with alcoholic-water mixed solution.And the alcohol-water ratio was 3:1,2:2,1:3,and 0:4,respectively.The in vitro antibacterial method was used to evaluate the bacteriostatic rate of each extract against E.coli and Staphylococcus aureus.The test results were:90.6%,80.5%,79.2%,75.5%and 88.6%,81.2%,75.0%,74.6%.(2)The Box-Behnken design and response surface method are used to establish a prediction model of the nanofiber diameter and the concentration,voltage and distance in the electrospinning process parameters.The model is:Y=-274.49625x₁-257.20875x₂-69.32312x₃-1.29x₁x₂-2.02375x₁x₃+0.305x₂x₃+23.38375x₁²+7.98281x₂²+2.93094x₃²+3631.74 R² is 0.96363,which indicates that the correlation is good.The optimal spinning process determined based on the model is:PVA concentration of 7.21%,spinning voltage of16.51KV,and spinning distance of 14.49cm.The predicted nanofiber diameter is120.99nm,and the experimental measured value is 122.36nm.(3)Glutaraldehyde gas phase cross-linking of nanofiber films.This improves the water resistance of the film.Then the effects of cross-linking time on the contact angle,mechanical properties,antibacterial properties,porosity,and water vapor transmission rate of the nanofiber membrane are studied.The results show that nanofiber membranes perform better after 2h and 4h of crosslinking.