Silk fibroin/sodium alginate composite porous materials with controllable degradation

In this study, silk fibroin (SF)/sodium alginate (SA) porous materials (PMs) with different blend ratios were generated using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as crosslinking agent by a simple freeze-dried method. Degradation experiment of SF/SA PMs have been systematically investigated up to 18 days in Collagenase IA solution at 37 °C, Phosphate buffer saline (PBS) solution without enzyme was used as a control. The results showed SF/SA 50/50 PMs exhibited a lowest rate of weight loss, about 68% of the weight retained within 18 d in Collagenase IA solution. SEM images indicated Collagenase IA can degrade fibroin leading to collapse of the pure SF PMs, while SF/SA 50/50 PMs still possessed integrity of pore structure during enzyme degradation with increasing exposure time. The crystalline structure of the SF in the SF/SA PMs changed to silk II after degradation for 18 d. Furthermore, the results of the in vivo degradation by subcutaneous implantation in rats showed that all PMs can be degraded at different levels, and exhibited good subcutaneous histocompatibility to the host animals. The degradability was strongly correlated to the blend ratios in a series of SF/SA composite PMs, and insights gained in this study can serve as a guide to match desired degradation behavior with specific applications for the SF/SA composite PMs.