Effect of molecular weight on electro-spinning performance of regenerated silk

Owing to the excellent biocompatibility of silk fibroins (SFs) and ease of fabrication of nano-fibrous webs by the electro-spinning technique, electro-spun SF webs have attracted the attention of researchers for various biomedical applications, including their use as tissue engineering scaffolds and membranes for guided bone regeneration. In this work, the effect of the molecular weight (MW) and concentration of SFs on the structure and properties of the electro-spun SF webs was examined. The fiber morphology and porosity of these SF webs were strongly affected by the viscosity of the SF dope solution. It was found that the electro-spinning rate of the SF solution could be increased significantly (7.5 fold) by controlling the MW and concentration of the SF. Interestingly, as the SF MW and concentration (i.e., s​olution viscosity) increased, the extent of β-sheet crystallization of the SF decreased, leading to a decrease in the overall crystallinity. The strength and elongation of the electro-spun SF web decreased with an increase in the web porosity (i.e., increasing SF concentration) and a decrease in the MW of the SF.