A Promising Wound Dressing from Regenerated Silk Fibroin Sponge with Sustain-ed Release of Silver Nanoparticles

A silk fibroin(SF)spongy wound dressing incorporated with silver nanoparticles(Ag-NPs)was developed for biomedical applications.Ag-NPs were efficiently synthesized in situ via ultra violet(UV)with AgNO_(3) as precursor and silk fibroin as reducing and protecting agent,respectively.After lyophilization,the formed silk fibroin spongy wound dressing(SFWD)exhibited polyporous morphology and inner lamellae structures,with uniform dispersion of Ag-NPs.The porous structure provided SFWD with the ability to absorb tissue exudatealmost 6 times of its own weight,which could guarantee the sustained release of Ag-NPs.By methanol treatment,SFWD showed much improved mechanical properties and more stable to protease XIV.The cyto-compatibility of SFWD was supported by normal adherence and proliferation of NIH3T3 fibroblasts in sponges extracting culture medium.More important,the SFWD showed significant growth inhibition in both plate culture assays and bacterial suspension assays,with Gram-positive(Staphylococcus aureus)and Gram-negative(Pseudomonas aeruginosa and Escherichia coli).In a cutaneous excisional mouse model,the average healing rates of SFWD was significantly higher than control and commercial bandages.The hematoxylin-eosin(HE)staining results of the wound section also showed that SFWD could recruit more cells and promote tissue formation on the wound edges.