| An ageing population increases the proportion of older people whose cutaneous wounds is difficult to heal,which has affected social harmony and reduced people's happiness index.Thereinto,bacterial infection is one of the significant factors affecting wound healing process,of which wound exudate,containingsa large number of inflammatory cytokines and proteases that reduce the speed of wound healing.However,the new nano dressing has good antibacterial and healing effects,its research and development gives patients with chronic wounds hope to cure and allivate suffering,and its market prospect is broader.Polyvinyl alcohol(PVA)has good mechanical properties,high hydrophilicity,film-forming ability,cohesiveness and biocompatibility,etc.Sodium alginate(SA)has extensive sources and low price,and it has good biocompatibility and high hydrophilic,which is ideal for fibrosis and film forming.So,its prospects is broader in the field of drug release system and pharmaceutical industry.PVA/SA nanofibers prepared by electrostatic spinning have the characteristics of minor diameter and high specific surface area and porosity.Furthermore,introducing antibacterial agent——berberine(BER)into PVA/SA nano fiber can effectively improve the antimicrobial properties of materials,because of the synergistic effect of PVA/SA and antimicrobial agents.The average diameter of PVA/SA nanofibers is used as response value to fitting two polynomial regression model,through the analysis of variance and significant test,the interaction between SA concentration and distance,SA mass fraction and voltage,voltage and distance has significant influence on the nano fiber average diameter.A prediction model for diameter of nanofibers by response surface is:Y=6781.30-50.60X1-239.98X2-314.64X3-4327.34X4+1.57X1X2+0.99X1X3-21.95X1X4+7.03X2X3-30.29X2X4-64.23X3X4+0.34X1^2+2.93X2^2+6.88X3^2+5332.75X4^2,The R2 value is 0.8807.The reliability and experimental value of the model are in good agreement with the predicted values.Based on the analysis of response surface diagram,the minimum diameter—242.12nm when SA content was 31.85%,voltage was 18.00kV,distance was 14.19cm,flow rate was 0.61ml/h.Using fuzzy evaluation method to evaluate different ratios of PVA:SA,Nano fiber membrane had the best comprehensive performance when PVA/SA was 10:0.,followed by 8:2,next was 7:3,and finally was 6:4.That is,with the increase of SA content,the comprehensive properties of PVA/SA nanofibers are reduced.Using ethanol solution of calcium chloride as cross-linking agent to crosslink the PVA/SA/BER nano fiber membrane.When calcium chloride concentration was 4%,the cross-linking time was 4h,water absorption properties of PVA/SA/BER nano fiber was best,its absorption rate was 1257%,the maximum value of fracture strength reached 4.17MPa,and the fracture strength was 100.48%higher than that before cross linking.When the dosage of berberine was 6%,the inhibition rate of PVA/SA/BER nanofibers on Escherichia coli was 99.41%,and the inhibition rate to Staphylococcus aureus was 97.89%. |
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