Nanofiber Induced Silk Fibroin Nanofiber/Silk Fibroin (SFNF/SF) Fibrous Scaffolds for 3D Cell Culture

Fibrous 3D scaffold with small fiber diameter has the similar topographic and structural characteristics of native extracellular matrix (ECM), which provides the beneficial microenvironment for cell adhesion, growth, migration, proliferation. However, the pore structure of the biopolymer scaffold is crucial for cell regulation and tissue regeneration in practical application. In this report, we proposed a nanofiber induced silk fibroin nanofibers/silk fibroin (SFNF/SF) fibrous scaffold with homogeneous micron pores using fast freeze-drying technology under − 196 °C. The physical, chemical and biological performance of the scaffold was investigated. Ethanol post treatment of the scaffold led to the conformation transition of silk fibroin from random coil (silk I) to beta-sheet (silk II) and increase of the crystallinity of the scaffold, which greatly improved the stability of the scaffold in water. Scaffolds made from 2 to 6% SFNF/SF solution with SFNF/SF ratio ranging from 1:1 to 1:8 exhibited three dimensional (3D) fibrous structure with porosity of 80–85% and pore size ranging from 5 to 15 μm due to the entanglement of the nanofibers. And the fibrous structure of the scaffolds can be adjusted by controlling the concentration of the SFNF/SF solution and the SFNF/SF ratio. Cell culture suggested that the 3D fibrous network structure with micron pores showed advantages for cell migration comparing with the lamella structure scaffold. After 7 day’s culture, cells migrated to about 240 μm inside the 6% 1:1 scaffold, while only about 160 μm inside the 6% 1:16 scaffold. The nanofiber induced micro porous SFNF/SF scaffolds by fast freeze-drying technology is potential for preparation of micron porous scaffold.