Abstract

Among natural materials, silk fibers boast unparalleled strength and elasticity. This has made silk ideal for use in apparel, medical sutures, and other high-performance materials. The unique profile of silk arises from the composition of its repetitive protein domains, which varies between species. We aimed to program the physical properties of synthetic silk in two ways: by modularizing spider silk genes and tuning their properties through directed assembly, and by fusing accessory proteins to silkworm and honey bee silks to expand their functionality. To overcome the challenge of creating large, repetitive, GC-rich genes, we adapted Iterative Capped Assembly to ligate spider silk genes in specific ratios, orders, and lengths. The recombinant silks were expressed in E. coli then spun via standard wet spinning. This provides a platform for standardizing the customization of synthetic silk fibers, and exploring their potential as multipurpose biomaterials.

Projects

Customizing Silk

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

We have adapted a novel cloning technique called iterative capped assembly (ICA) to rapidly and controllably assemble spider silk genes. Our new process will dramatically shorten the time and expense needed to assemble these repetitive parts. Click here to learn more.

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.