A novel route to prepare dry-spun silk fibers from CaCl2-formic acid solution

Regenerated silk fibroin (RSF) fibers with high strength and extensibility were firstly dry-spun from CaCl2-formic acid (FA) solution. The dissolution of degummed silk in CaCl2-FA was simple and efficient, and featured nanofibril-preservation. The preserved nanofibrils were responsible for the good physical properties of RSF fibers from such a spin solution. The simple and efficient spin process of RSF is very useful in an effort to utilize waste material and produce functional materials, such as biodegradable silk sutures.