Fabrication of water-stable silk fibroin scaffolds through self-assembly of proteins

Silk fibroin (SF) is a promising biomaterial and has been widely used in tissue engineering. However, most of the currently used fabrication techniques require the use of organic solvents that cannot be removed thoroughly. The residual organic solvents reduce the proliferation capacity of cells. In this study, we developed water-insoluble SF scaffolds by a simple temperature induced method without the addition of organic or inorganic substances. Temperature was used to tune the self-assembly of SF during the freezing process, which resulted in water stable porous scaffolds directly. Compared with the traditional methanol treated scaffolds, the current scaffolds presented a less crystalline structure, lower elasticity modulus and faster degradation rate. In addition, human umbilical vein endothelial cells (HUVECs) showed an enhanced adhesion capacity, better spreading morphology and a faster proliferation rate on the scaffold. Investigation of the scaffold formation mechanism revealed that the performance of the current scaffold was dominated by the storage time and temperature, which tuned the self-assembly process of SF by controlling the molecular activity and contributed to the low crystallinity of the structure and water-insolubility. The results indicated that this low crystallinity scaffold holds great promise as a candidate for soft tissue repair materials.