Study On Construction Of Bionic Antibacterial Multi-functional Dressing Using Electrospinning Technology

Objects:The ideal wound dressing should have many physical and chemical properties such as air permeability,moisture retention,water absorption,antibacterial activity,and promotion of cell migration,differentiation and proliferation.Electrospinning technology can be used to prepare fibrous membranes that are highly similar to the spatial morphology of the extracellular matrix,which has great application potential in wound healing.Nanosilver(AgNPs)has potent and broad-spectrum antibacterial properties,but if it comes into contact with traumatic tissues in large quantities,it will enter the interior of cells and damage cellular DNA,inhibit ATP production,cell proliferation and migration.In this study,we attempted to design and prepare a sandwich-structured bionic antibacterial dressing loaded with AgNPs by electrostatic spinning technique,in order to achieve water absorption,moisture retention,antibacterial activity and tissue growth promotion in wound while overcoming the cytotoxicity of AgNPs and providing an effective tool for wound treatment.Methods:1.A three-layer dressing with an inner layer of polycaprolactone(PCL)/gelatin(Gel),an intermediate layer of PCL/Gel/AgNPs,and an outer layer of pure PCL was prepared using electrostatic spinning technology.2.The electrospun dressings were examined by scanning electron microscopy(SEM),water contact angle detection,moisture retention capacity detection,X-ray diffraction analysis,Ag release test and other related tests to evaluate the spatial morphology of the dressing,loading and released of AgNPs,water absorption and other physical properties of the dressing.3.The agar diffusion method was used to compare the antibacterial performance of bionic dressings with different AgNPs contents with that of silver sulfadiazine(SSD,Urgotul,France)dressing against Escherichia coli.4.After inoculation of normal human skin fibroblasts on the hydrophilic surface of the dressing,the CCK-8 method was applied to measure the effect of electrospun dressing with different AgNPs contents versus SSD dressing on cell proliferation.The growth pattern of the cells on the dressing surface was observed by scanning electron microscopy(SEM)as well as fluorescence microscopy under Phalloidin-i Fluor 488 and DAPI cell staining.5.A full-thickness skin defect model of SD rats was established.Four wound surfaces were made on the back of each rat and covered with Gauze,electrospun dressing without AgNPs(PCL/Gel),electrospun dressing with 10% AgNPs in the middle layer(PCL/Gel/10%AgNPs)and SSD dressing,respectively.The wound healing was observed with naked eye,and the tissue growth process was observed under microscope after HE and Masson staining.Results:1.Electrospinning technology was used to prepare a three-layer structured dressing with an inner layer of polycaprolactone(PCL)/gelatin(Gel),an intermediate layer of PCL/Gel/AgNPs,and an outer layer of pure PCL.2.The inner,middle and outer layers of the electrospun dressing all exhibit a skeleton-like spatial structure of extracellular matrix.The AgNPs particles are successfully loaded on the middle layer of the fibers.The outer layer of the dressing is highly hydrophobic and the inner layer is highly hydrophilic,The maximum water absorption of the dressing is 6.8 times of its own mass,The water evaporation at 37°C for 10 h is 50% of the maximum water absorption.Ag release from electrospinning dressings was positively correlated with the content of Ag in the dressings,but all of them were lower than that from SSD dressings.3.The size of the antimicrobial ring: SSD > PCL/Gel/10% AgNPs > PCL/Gel/5%AgNPs > PCL/Gel/1% AgNPs.4.In CCK-8 tests,there was no significant difference in cell proliferation between electrospun dressings with different AgNPs loading(P > 0.05);SSD dressings had lower cell numbers than all electrospun dressing groups from 1 day after cell inoculation until the end of the observation on day 5(P < 0.05);Scanning electron microscopy and fluorescence microscopy showed that the cells on the surface of the electrospinning dressing adhered well and the cell morphology gradually changed from oval shape to long spindle shape.5.Wound healing rate: PCL/Gel/10% AgNPs > PCL/Gel > SSD > Gauze;the number and density of inflammatory cells in the wound tissue of PCL/Gel/10% AgNPs and SSD groups were similar during wound healing and were lower than the other two dressings;PCL/Gel/10% AgNPs dressing promoted microvessel formation and collagen production at a faster rate than the other three dressings.Conclusions:The electrospinning dressing containing AGNPs has the characteristics of bionics,water absorption,moisturizing,antibacterial,anti-inflammatory and promoting wound healing.This sandwich-like structure design cleverly balanced the antibacterial and antiinflammatory advantages of AgNPs and possible cytotoxicity problems when applied on the wound surface,and is a bionic antibacterial wound dressing worth further investigation.