In Situ Assembly Of Ag Nanoparticles(AgNPs)accelerated Wound-healing Capabilities Of A Novel Dressing Fabricated From Silkworm Cocoon

Skin wounds can be seen everywhere in our daily life,slight wound may lead to wound infection,wound place appear red,swollen and fester,more seriousthreatens people’s life.Bacterial infection is the culprit,bacteria can directly remove the wound surface,can cause the wound appear a large number of exudate,decomposition of extracellular matrix protein and a variety of growth factors,prevent skin regeneration and wound closure,significantly affect the process of recovery.Sosterilization eliminate infection in time is the key during wound care.In this study,we combine the advantages of natural fibroin and sericin in cocoon,using the natural structure of silkworm cocoon,preparation of high transparency,high extensibility dressing.Sericin-containing porous silkworm cocoon wound film was initially prepared by treating silkworm cocoons in a Ca Cl2-C2H5OH-H2 O solution,as it is much easier to achieve homogeneous dispersion of sericin.By subsequently immersing SCWF in Ag NO3 aqueous solution,the Ag+ molecules immobilized in the porous silkworm cocoon wound film were reduced in situ to form Ag NPs by sericin in the matrix.At the same time,to evaluate the physical and chemical properties,antimicrobial properties,cytotoxicity and wound healingpropertiesof antimicrobial dressings.The results are as follows:1.Degumming of silk cocoons with papain,on the basis of single-factor experiments,an orthogonal experiment was carried out.Through degumming rate calculation for the silk cocoons material after treatment,scanning electron microscope and mechanical performance testing we found that sericin impact on the structure of cocoon.The content of sericin is lower,the structure of cocoon is loose,flexible andstress decreases,permeability increase.The cytotoxicity experimental results show that the cocoon of pore structure is more advantageous to cell proliferation after 30 min treatment.2.A series of silkworm cocoon wound film(SCWF)wound dressings are prepared by immersion in a Ca Cl2-C2H5OH-H2 O solution for different treatment times.On the basis of single-factor experiments,preparation of SCWF with treatment time and temperaturewas investigated in this paper.The results show that the treatment temperature is 60±2℃,time of 120 min,SCWF-120,exhibits excellent transparency,a high swelling ratio,and good extensibility.These results demonstrate that the proposed approach may be utilized in the design of antibacterial materials with promising applications in wound dressing.3.In the experiment ofthecocoon porous membrane in situ load Ag NPs,throughsingle-factor and L9(34)orthogonal experiment theconcentration of Ag NO3,treatment temperature and treatment time was investigated.The experiment result expresses thatthe optimum process conditions of preparation SCWF-Ag NPs including the concentration of Ag NO3 is 150 m M,treatment temperature is 20℃ and treatment tim is 3h,the study also found thatwith the higher content of silver nanoparticles,SCWF material pore size becomes larger,gas permeability and water absorption performance improved significantly,at the same time the ductility can also get a boost,but breaking strength will decline.4.SCWF-Ag NP150 and SCWF-Ag NP200 dressing exhibited a higherthe physical and chemical properties,to explore more clearly Ag NPs in the role of antimicrobial properties and cytotoxicity.Higher concentration of SCWF Ag NP200 dressings than its antimicrobial properties SCWF-Ag NPs because SCWF-Ag NP200 reductive have been the Ag NPs size is bigger,and has a wide distribution,so the antibacterial performance declines.In addition,we found SCWF-Ag NP150 no significant cytotoxicity by cell culture test,instead of the higher Ag NPs content SCWF-Ag NP200 dressing is higher cytotoxicity.The resultsof SCWF-Ag NP150 excellent biocompatibility,anti-bacterial performance,and good extensibility.5.Furthermore,in vivo experiments indicated that SCWF-Ag NP150 dressing was able to significantly accelerate the healing rate of infected wounds in New Zealand White rabbits compared to the standard Mepitel? dressing,and histological examinations reveal that SCWF-Ag NP150 aided in the successful reconstruction of intact and thickened epidermis.And histological examination revealed that it aided in the successful reconstruction of intact and thickened epidermis during 14 days of healing of impaired wound tissue.