Abstract

Spiders have evolved an arsenal of silk threads for various applications, using combinations of highly-repetitive silk proteins. These fibers have an extremely high range of tensile strength and elasticity, and along with their low immunogenicity, are desired by the military, medical, and fashion industries. However, spider silk farming is impractical, and alternatives are necessary for large-scale production. Inspired by nature’s design, we aim to engineer E. coli to produce genetically programmed synthetic fibers, and standardize the customization of their physical and functional properties. We have adapted Iterative Capped Assembly to modularize and flexibly control the assembly of silk domains that confer strength or elasticity in specific ratios. Varying the composition of the silk genes, or adding other functional proteins will allow precise fine-tuning of the resulting properties, and expand their practical utility. This platform can be readily applied to assemble other highly-repetitive proteins, or large genes from libraries of parts.

Projects

Customizing Silk

Modifying the genetic structure of silk can create a diverse new range of biomaterials.

With spider silk as our basis, we started to experiment with the genetic structure of silk. We rearranged portions of the repetitive DNA code to see how it affected the strength, elasticity, and spinning capabilities using Golden Gate Cloning and Iterative Capped Assembly. Click this text to learn about this portion of our project in-depth.

Functionalizing Fibers

By attaching various proteins, we can create silk with specific applications.

Glowing silk is an idea that appeals both to the scientific and artistic worlds. It is a proof of concept for the scientists, demonstrating how we are able to functionalize silk fibers, and an interesting new material to work with for the artists. This method can be applied to different kinds of proteins with different functions as well, but every idea has to start small. To see how we attached GFP to our silk constructs, click this text.

Processing Silk

Engineering our silk is only half the work, creating a tangible product is the rest.

After some stumbles in the beginning of summer when our makeshift rotary jet spinner failed to work, we decided to look into different methods of spinning synthetic fibers. We tested extrusion with a syringe pump, which gave us very thin, fragile fibers. Click this text to jump into the action and watch fibers take shape from solution.