Liquid Silk & Shellfish Biomaterials as an Alternative to Plastics
Ruini Xiong, Crystal Zheng
Floor Location : S 046 N
The Liquid Silk and Shellfish project was inspired by the current issue of plastic waste and the environmental damage done by plastic drinking straws. While exploring liquid silk as an insoluble, durable and compostable biomaterial, we have linked to the issue of global plastic waste and the local Vancouver straw regulations. Although many biomaterials are being produced to reduce plastic waste, there is often a tradeoff of strength for sustainability. Our project explores the combination of silk and chitosan derived from shellfish waste to produce a sustainable and viable plastic alternative. By melting silk fibres to their protein building blocks and blending these with shellfish derived chitosan, we created several samples of plastic-like films. While this offers a compostable plastic alternative, it can also be used as a biocompatible “body bandage” for tissue engineering and for drug delivery.
Bombyx mori (silkworm) cocoons have been historically regarded for their fibre strength. Silk is famous for producing the familiar smooth and shining cloth, but it is less known scientific properties. Scientists have developed silk as a biomaterial that can be used in medical research due to its good biocompatibility. Our experiment doesn’t require high grade silk cocoons. Rather than unravelling each cocoon for thread, we cut up and melted them into their protein building blocks. This way, we allow the proteins to reassemble in water and form films upon drying. There are three structures in natural silk: silk I, silk II, and an air & water assembled interfacial silk III. Silk II structure is insoluble in water, which can be used to form strong films. Chitosan is a natural polymer, obtained from shells of shellfish - a large amount of waste from the seafood industry. Today, chitosan is used as a scaffolds in tissue engineering and high value wound healing application due to its biocompatibility and biodegradability. Combining chitosan with silk produces a strong SF/CS film with silk’s water-insoluble properties and stable structure, while chitosan fills in the gaps to increase durability. A chemical crosslinker, such as dextran sulfate, forms more stable bonds between the silk fibroin and chitosan.
For sustainability and to make this product free of silk worms, we can make DNA recombinants and grow proteins with yeast using DNA barcoding. This is much more efficient and cuts the long process of washing off sericin and melting down the silk fibroin. In addition to producing silkworm free silk, we may be able to trigger more Silk II structure formation using.