Preparation And Performance Study Of Antibacterial Chitosan/polyvinyl Alcohol Loaded Silver Sponge Dressing

In recent years,antibacterial sponge dressings have shown broad application prospects in wound healing,such as skin wounds,burns and diabetic wounds.The ideal wound dressing should have breathability,antibacterial properties and provide a moist environment that promotes wound healing.In this study,chitosan and polyvinyl alcohol with good biological properties were used as the main materials to prepare composite sponges.Chitosan has antibacterial、hemostatic and biodegradable properties.The addition of polyvinyl alcohol increases the mechanical properties of the dressing.Although chitosan has a certain antibacterial ability,it is not enough to provide a sterile environment for wounds.So nanosilver is added to increase the antibacterial performance of the composite sponge.In the follow-up study,curcumin and nanosilver are used for synergistic antibacterial.The main research content and experimental results are as follows:(1)Explore the best concentration ratio of chitosan and polyvinyl alcohol.After chitosan and polyvinyl alcohol were crosslinked by glutaraldehyde,glycerin was added as a plasticizer to improve the flexibility and mechanical properties of the composite,and then freeze-dried to prepare a composite sponge dressing.The basic performance of the composite sponge dressing was explored with three different concentration ratios(chitosan: polyvinyl alcohol 1:1,1:2,2:1).(2)The chitosan is used to prepare nano silver particles to increase the antibacterial ability of the composite sponge dressing.The method is simple,green,environmentally friendly,and does not require the addition of additional chemical reagents.The diameter of nano silver particles is about 10-20 nm,the maximum characteristic absorption peak is at 410 nm,and the pore diameter of the composite sponge dressing is about 100-250μm.This method uses three concentration gradients to prepare antibacterial dressings,with silver content of 0.01%,0.05%,and 0.1%,respectively.The cytotoxicity of composite sponge dressings with different silver content was tested through experiments,and the cell survival rates were 91%,82%,and 71%.(3)Nano-silver antibacterial has broad-spectrum antibacterial properties and is not easy to produce drug resistance,but the cytotoxicity produced by nano-silver is also a problem of widespread concern.Therefore,in subsequent studies,the antibacterial part of the composite sponge dressing was improved,using nano-silver and curcumin for synergistic antibacterial.Add tannic acid and ferric chloride to the curcumin solution.After the tannic acid and ferric chloride are coordinated and combined,a stable film is formed on the surface of curcumin,and then silver nitrate solution is added to utilize the surface of the curcumin particles.Tannic acid reduces silver nitrate to nano-silver particles.The diameter of the curcumin and nano silver particles(Cur@Ag)prepared by the method is about 20-80 nm,and the maximum characteristic absorption of the antibacterial agent is 430 nm.The cell survival rate of the composite sponge dressing containing nano-silver and curcumin was 91%,85%,and 81%,which was about 10%higher than that of the nano-silver composite sponge dressing prepared by the chitosan in-situ reduction method.(4)The elongation at break of the composite sponge is 25%-40%,and the tensile strength is 1.5 MPa-2.2 MPa.Compared with the pure chitosan polyvinyl alcohol sponge,the composite sponge with antibacterial agent has relatively better mechanical properties.The silver content of the composite sponge dressing prepared by this method is 0.001%,0.002%,and 0.003%,respectively.The minimum inhibitory concentration of curcumin against bacteria is 300μg/ml.In synergistic antibacterial,the curcumin concentration is 50 μg/ml.The dosage of curcumin is reduced by 6 times.The minimum inhibitory concentration of nano silver is 0.01%.But the synergistic antibacterial concentration of nano silver is 0.001%,which is about 10 times lower than using nano silver antibacterial alone.The synergistic antibacterial significantly enhances the antibacterial ability of curcumin and nano silver.(5)Establish a rat full-thickness skin wound model to study the effect of composite sponge dressing on wound healing.By wound healing area,H&E staining and Masson staining observation shows that compared with the control group treated with gauze,rats using the composite sponge dressing prepared in this study increased the wound healing area by about 10% within 15 days.The capillaries increase to form a continuous and uniform epithelial tissue,and the content of fibrous tissue also increases.