Preparation And Properties Of Regenerated Silk Fibroin Silver-loaded Wound Dressing

As the largest organ in human body,skin not only protects our normal metabolism,but also plays an important role in preventing ultraviolet radiation,bacterial infection,foreign body invasion and other harmful environmental factors.However,external injury often lead to tissue necrosis and damage the skin.According to the characteristics of ideal wound dressing,a silk fibroin spongy wound dressing?SFWD?incorporated with silver nanoparticles?Ag-NPs?was developed for biomedical applications.Ag-NPs were efficiently synthesized in situ via ultra violet?UV?with AgNO₃ as precursor and silk fibroin as reducing agent and protecting agent,respectively.Then the resultant solutions were lyophilized into sponge.The sponge was characterized with Scanning Electron Microscopy?SEM?and Fourier Transform Infrared Spectroscopy?FTIR?,and the formation of Ag-NPs was confirmed with Energy Dispersive Spectrometer?EDS?.The sponge exhibited uniform polyporous morphology with inner lamellae structures,which loaded with Ag-NPs.Besides,the porous structure provided it with the ability to absorb tissue exudate,and 6 times of its own weight of aqueous solution was able to be absorbed.More?-sheet structures were induced by methanol immersion?from 17.32%to 39.41%?.Increasing the SF concentration and induced by methanol,the sponge showed improved tensile strength and more stable to Protease XIV.SF concentration dominated tensile strength,and?-sheet dominated the stability.The antibacterial activity of sponge was confirmed with Gram-positive?Staphylococcus aureus?and Gram-negative?Pseudomonas aeruginosa and Escherichia coli?,all of which showed significant growth inhibition in both plate culture assays and bacterial suspension assays.Besides,the cytocompatibility of Ag-NPs loaded sponge was supported by normal adherence and proliferation of NIH3T3 fibroblasts in sponges extracting culture medium,compared with fresh cell culture medium in vitro.Furthermore,through scanning electron microscopy?SEM?,we observed that a great quantity of cells adhered to the Ag-NPs loaded sponge.A cutaneous excisional mouse model was used to dynamically observe the healing process of full-thickness skin defect.The full-thickness wounds were created on dorsal sides of mice,which were covered with SFWD and control sponge.The average healing rates of SFWD was markedly higher than control,and hematoxylin-eosin staining?H&E?showed the same,suggesting SFWD may provide a useful strategy for development of new wound dressing.