Preparation of a silk fibroin spongy wound dressing and its therapeutic efficiency in skin defects.

A novel silk fibroin spongy wound dressing (SFSD) incorporated with nano-Ag particles was prepared by coagulating with 1.25-5.0% (v/v) poly(ethylene glycol diglycidyl ether) (PGDE). The mechanical properties, moisture permeability and hygroscopicity of SFSD, and the nano-Ag release behavior from SFSD were evaluated. The results showed that the soft SFSD had satisfying tensile strength and flexibility, as well as excellent moisture permeability and absorption capability of wound exudates. The moisture permeability was 101 g/m(2) per h and the water absorption capacity of SFSD was 595.2% and 251.9% of its own weight in dry and wet states, respectively. The nano-Ag in the SFSD was released continuously at a relatively stable rate in PBS resulting in a remarkable antibacterial property. A rabbit model was used to dynamically observe the healing process of full-thickness skin defects. Full-thickness wounds were created on the dorsal side of rabbits, which were covered with SFSD and porcine acellular dermal matrix (PADM) for comparison. The mean healing time of the wounds covered with SFSD was 17.7 ± 2.4 days, significantly shorter than that with PADM. The histological analysis showed that the epidermal cell layer formed with SFSD was very similar to normal skin, suggesting that SFSD may provide a good component for the development of new wound dressings.