Cellulose–silk fibroin hydrogels prepared in a lithium bromide aqueous solution

Here, we present a new process for the preparation of cellulose–silk fibroin hydrogels using a concentrated lithium bromide (LiBr) aqueous solution. After mixing, the solutions of cellulose and silk fibroin that had each been dissolved separately in aqueous LiBr, the cellulose forms a gel as the solution cools to approximately 70°C, and silk fibroin is regenerated via treatment in methanol. Three grades of cellulose–silk fibroin hydrogels are prepared by controlling the amounts of cellulose and silk fibroin. The gels have highly porous, three-dimensional networks composed of long, interconnected fibrils. Through X-ray diffraction and ATR-FTIR analysis we show that the dissolution-regeneration of cellulose and silk fibroin induces a structural change in the crystal structure of cellulose II and silk II. While the porosity and swelling ratio of cellulose–silk fibroin gels is significantly reduced with the increased silk fibroin content, all the gels show high water uptake. The enzymatic degradation rates of cellulose–silk fibroin gels obviously reflect differences in the silk fibroin content, and cell adhesion and growth on cellulose–silk fibroin gels is enhanced with increased silk fibroin content. These cellulose–silk fibroin gels could provide novel properties that would be useful for biomaterial matrix applications.