Self-assembled green composites of silk fibroin and microfibrillated cellulose

Abstract: Regenerated silk fibroin (SF) and microfibrillated cellulose (MFC) offer sustainable options as the next generation of green materials based on their desirable properties for multiple applications, also, can be obtained from underutilized side streams in other industries. To date, the SF-MFC composites manufacture relies on multiple steps and cross-linking reactions, which increase their cost and footprint. We propose a sustainable and green alternative for the composite fabrication by simply inducing secondary structure formation of SF on MFC induced through methanol (MeOH) post-treatment. Molecular interactions between MFC and SF were investigated through charge density and quartz crystal microbalance experiments to determine their self-assembly mechanisms, which showed that the SF tended to adsorb on MFC without hindering its capacity to form β-sheet structures when immersed in MeOH. This methodology allowed the formation of homogeneous cryogels with low weight, good dimensional stability, and high relative porosity without the use of external agents.