Mechanisms and control of silk-based electrospinning.

Silk fibroin (SF) nanofibers, formed through electrospinning, have attractive utility in regenerative medicine due to the biocompatibility, mechanical properties, and tailorable degradability. The mechanism of SF electrospun nanofiber formation was studied to gain new insight into the formation and control of nanofibers. SF electrospinning solutions with different nanostructures (nanospheres or nanofilaments) were prepared by controlling the drying process during the preparation of regenerated SF films. Compared to SF nanospheres in solution, SF nanofilaments had better spinnability with lower viscosity when the concentration of silk protein was below 10%, indicating a critical role for SF morphology, and in particular, nanostructures, for the formation of electrospun fibers. More interesting, the diameter of electrospun fibers gradually increased from 50 to 300 nm as the concentration of SF nanofilaments in the solution increased from 6 to 12%, implying size control by simply adjusting SF nanostructure and concentration. Aside from process parameters investigated in previous studies, such as SF concentration, viscosity, and electrical potential, the present mechanism emphasizes significant influence of SF nanostructure on spinnability and diameter control of SF electrospun fibers, providing a controllable option for the preparation of silk-based electrospun scaffolds for biomaterials, drug delivery, and tissue engineering needs.