Facile Preparation of Biocompatible Silk Fibroin/Cellulose Nanocomposite Films with High Mechanical Performance

Although regenerated silk fibroin (SF), which has excellent biocompatibility, biodegradability, and a low inflammatory response in vivo, has promising applications in tissue engineering, the mechanical properties and biofunctionality must be further improved to satisfy tissue-engineering applications. Cellulose nanofibrils (CNFs) are promising candidates for bionanocomposite production due to their ultrahigh strength and excellent biocompatibility. In this study, CNFs were extracted directly from microcrystalline cellulose using an aqueous lithium bromide solution, a typical solvent for dissolving SF fibers. As a result, SF/cellulose nanocomposite films with improved tensile strength were fabricated using aqueous lithium bromide solution as a novel solvent system for the dissolution and blending of SF and cellulose. The extracted CNFs were homogeneously dispersed within the composite films through the rapid gelation of cellulose. The degradability of the composite films in a protease XIV solution was strongly dependent upon the SF component, which significantly promoted the degradation rate of composite films. Adhesion and proliferation results showed that SF/cellulose nanocomposite films promoted cell viability. Our work suggests a facile and effective approach for designing SF/cellulose nanocomposites that may have wide potential applications in tissue engineering.