The fashion industry has estimated greenhouse gas emissions (GHGs) between 5-10% of global GHGs, which is expected to grow 30% by 2030. Materials derived from crude oil and methane account for 2/3 of textiles, including polyester and nylon. Most synthetic textiles are not biodegradable, so an inevitable consequence is plastic pollution. Microplastic pieces of the pollutants are now recognized as omnipresent human health risks. Fossil-based dyes and pigments in textiles also cause environmental harm. As textile manufacture primarily occurs in developing nations, under-resourced communities bear the environmental burden of our fashion industry.

Sustainability is a top issue for fashion industry leaders. The top ten fashion companies, including H&M, Lululemon, Adidas, and Inditex, have committed to using more sustainable materials, even at increased financial cost. Textile dyeing is also a large concern, and fashion companies have shown interest in more sustainable dyeing processes. However, innovative textiles must achieve durability, comfort, performance, and quality hand feel at a palatable price for general consumers. Our Track I Convergence Accelerator project aimed to create biobased textile innovations that can match or surpass fossil-based synthetics at prices accessible to general consumers. Our design philosophy leveraged renewable, inexpensive plant biomass as a majority component while using small quantities of engineered recombinant proteins to dramatically improve fiber performance, hand feel, coloration, and aesthetics.

In this project, we demonstrated the novel fabrication of hemp textiles infused with small quantities of recombinant spider silk protein. We chose hemp bast fiber (Image 1) as a base matrix because hemp is a renewable and biodegradable material that grows quickly, with less water usage and ecological footprint than cotton. Despite the environmental benefits of hemp fibers, hemp yarns and fabrics are typically relegated to workwear and functional accessories, as they are considered too rough, stiff, and dull for fashionwear. Hemp also lacks the extensibility and toughness of synthetic fibers. Our work developed a new process for infusing commercially purchased hemp yarns and fabrics with recombinant spider silk proteins (spidroins) to enhance their properties for textile applications. This process used deionized water as a solvent and did not require reactive chemicals for fixation. From the start, we prioritized cost efficiency, and our process was designed to use a minimal amount of spidroin solution. We found that the properties of hemp yarns can be noticeably enhanced with as little as 0.25 wt% spidroin in the final material. Our infusion process improved the softness, toughness, strength, luster, and flame retardancy of the material.

We developed a preliminary cost model of our production process to assess market penetration potential. Based on our experimental results, we estimated the production cost of our silk-infused hemp fabric to be $31 per square yard, making it competitive with existing luxury fabrics and far cheaper than other biobased textiles recently marketed (e.g., made using algae, fruit peels, mycelium, recombinant protein).

Our project also investigated scaling up spidroin production using an E. coli strain engineered in our lab specifically for producing recombinant spidroins. We worked towards developing a purification protocol that required a minimal number of steps to decrease the overall production cost. Traditionally, recombinant spidroins are purified using a complex multi-step process. We developed a one-step protocol that simultaneously disinfects and purifies the recombinant spidroins.

Lastly, our project explored the development of chromoproteins as a biodegradable and renewable, yet mostly unexplored, alternative to synthetic dyes and pigments. Naturally made by corals and sea anemones, where they function as photo-protectants, chromoproteins display a variety of vibrant colors under visible light. Our work synthesized a panel of five vivid chromoprotein colors (Image 2) using E. coli hosts. Our results demonstrated a method for improving their production speed. We also showed that that incorporating chromoproteins into a silk coating enabled color retention when dried and furthermore protected the chromoprotein against detergent. Hemp fabrics could be dyed by simply immersing the fabrics in an aqueous chromoprotein solution without mordants or chemical fixatives, thus suggesting that chromoproteins can potentially be utilized as an eco-friendly textile dye.

Last Modified: 09/30/2024
Modified by: Runye H Zha