Double-decker scaffolds made of silk fibroin

Silk fibroin (SF) of the Bombyx mori silkworm has been widely studied in tissue engineering due to the combination of mechanical strength with versatility in processing and biocompatibility. Electrospinning, freeze drying and salt leaching are commonly used techniques to form 3D-scaffolds. Microarchitecture and fiber orientation within scaffolds can have significant effects on various cell behaviors including cell migration, orientation, adhesion and proliferation dictating cellular function and influencing tissue growth. Afterwards, a final curing manipulating the secondary structure of fibroin (i.e. the ratio between the β-sheets and random-coil regions) is required to improve its water stability and enhance mechanical properties of the scaffold. To accomplish this goal, processes based on the use of organic solvents, water-based annealing or water vapour at room temperature have been proposed. The present work reports the impact of freeze drying method on the architecture and mechanical properties of SF scaffolds aiming to obtain a sponge- or oriented lamellar-like structure by a solvent free process.