From Silkworm to Silk Protein – Sustainably Upcycling Silk By-Products

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The Legend of Silk

The history of silk has unraveled over thousands of years. It is a tale of accidental discovery, fierce protectionism, and the launch of a valued industry. From its origins and exclusivity in China to modern times, where silkworms are farmed around the globe, silk has enchanted industry titans and fashion icons alike.

The legend of silk’s discovery dates back 5,000 years. One day, resting under the shade of the white mulberry tree, Leizu, China’s Yellow Empress was transfixed by a cocoon that fell into her teacup and began to unravel. The Empress located the source of the cocoon – the silk moth bombyx mori – and began cultivating silkworms.

She is said to have invented the reel, which joins the strands into thread, and the loom to weave the threads into vibrant fabric. The discovery of silk and the beginning of sericulture was transformative. It brought riches to China and the “Silk Road” carried the famed fabric and other goods west.

Silk was considered a state secret and successive Chinese rulers prohibited the export of live silkworms, resulting in a monopoly on silk production and trade in silk fabric for centuries. It was not until the 6th Century, when monks smuggled bombyx mori eggs from China, that silk production was introduced in the west.

Silkworms are now cultivated and around the world and woven into prized fabrics, earning silk the title ‘the Queen of Fiber’.

Silk’s Other Secret

Although the silkworm was cultivated solely to make thread and fabric, it continues to amaze us. In its final stage of larval development, the silkworm produces fibroin and sericin, two remarkable natural proteins with a host of uses beyond the traditional application.

Because of their biocompatibility with human skin, silk proteins have captured the attention of scientists who are developing modern biomedical, cosmetic, and industrial applications and see the benefits of using them in various treatments, products, and methods.

Fibroin makes up 75% of the cocoon and is the main ingredient in silk fiber production. But it has an array of additional benefits. Recognized for its compatibility with living tissue, it has been used for medical sutures for decades. Recent research is focused on its “good biocompatibility, slow biodegradability and excellent mechanical properties” in identifying an array of additional bio-medical and industrial uses. From tissue engineering and antibacterial wound dressings to bio-membranes and UV protection, the list of fibroin applications continues to grow.

Sericin, the other protein, holds the filaments coming out of the moth. Until recently, sericin was considered a waste by-product, with high potential but little industrial use due to the lack of industry-standard production.

With 18 amino acids and the potential for polymerization, sericin proteins have demonstrated efficacy in cosmetics products as well as bio-medical functions.

Extracting and offering high-quality silk proteins with consistency and traceability is expensive and challenging to deliver at scale because the proteins are directly linked to sericulture.

SeriTech has developed a solution.

The SeriTech Solution

SeriTech redefines old methods with an innovative, proprietary process to upcycle silk by-products and offer fibroin and sericin proteins at scale.

Raw material supply previously hampered production capacity and the best raw material – the cocoon – remains elusive and costly. “Cocoons are rare to find and are very expensive.” (1) An essential component of the SeriTech solution is the creation of an ecosystem that secures raw material supply.

Inefficient and outdated processes have limited protein production and resulted in inconsistent quality. The goal, uniformity, with protein chain integrity, is shaped by the technique employed. SeriTech has developed a proprietary process to consistently produce fibroin and sericin proteins.

A high temperature, high pressure (HTHP) water degumming procedure, or other method, separates fibroin and sericin. Research indicates the “hot-water extraction is a simple and environmentally friendly method that preserves the main characteristics of silk sericin.” It is the least toxic technique and activates the highest collagen production. Once separated, the company produces uniform, cost-effective proteins with guaranteed molecular quality.

Weaving Technology and Humanity

SeriTech Founder Saimai Cunvong has successfully unified technology and humanity, bridging her family heritage and lifelong attachment to silk farming, in assembling a cooperative of thousands of Thai silk farmers to ensure supply and enable the company’s proprietary technology to function at scale.

“Growing up on a silk farm, I lived the cycle of silk. I was intrigued with the discarded by-product and asked myself: ‘what if there were a way to upcycle this into something useful?’ That set me on a lifelong path of re-discovering silk. We are creating unique, innovative, and effective healthcare and skincare products for the 21st century. SeriTech weaves technology and humanity, the result of my familiarity with sericulture and the benefits of silk proteins.”

In developing its sustainable process, SeriTech upcycles a range of silk waste, typically discarded by fabric maker creating useful proteins from an underutilized by-product. Fibroin for biomedical and industrial uses and sericin proteins for the cosmetics industry.

Continued research into of silk proteins is revealing new and important applications.

The Science of Silk Proteins

“Silk fibers made from fibroin have many uses in textiles (medical and industrial applications) mainly because of the unique properties of fibroin, such as water absorbency, dying affinity, thermo-tolerance, luster and insulation properties. Fibroin is also a raw material for producing precious fabrics, parachutes, tire lining materials, artificial blood vessels and surgical sutures.” (2)

Sericin proteins have an array of applications. The Cosmetic Ingredient Review panels calls sericin silk “glue”. With 18 amino acids it “enables easy cross-linking, copolymerization and blending with other natural or synthetic polymers.”

A review of sericin/calcium phosphate composite materials notes “silk sericin was considered an unutilized protein by-product from the textile industry, generating tons of residues every year. However, much effort has been dedicated to its recovery after being associated with numerous biological properties such as antioxidant, antibacterial, anti-coagulation and regenerative activities.”

SeriTech offers silk proteins in a range of molecular weights and its ability to scale-to-need positions the company at the forefront of the industry. With its capacity to supply proteins and brand-ready products, SeriTech is both a supplier and end user.

The company is now involved in R&D for specific applications for silk proteins, such as cardiovascular grafts, skin tissue regeneration, or collagen boost in ligaments. SeriTech is discussing with several pharmaceutical and biotech companies to co-develop medicinal products.  

Completing the Circle

A fresh understanding of the silkworm and silk proteins has completed the circle. In “Cradle to Cradle: Remaking the Way We Make Things“, the authors state the goal of upcycling is to prevent wasting potentially useful materials by making use of existing ones in creating a product with a higher value from waste of by-product streams.

SeriTech is committed to this philosophy, using ethical and sustainable practices to create a positive impact at each stage of the process, from the silk farmer to you.

SeriTech is excited to develop new applications for silk proteins in its resolve to develop technology that improves access to a range of dermocosmetics, vaccines and other medications. The journey from silkworm to silk protein has created a new legacy for the humble bombyx mori to impact people’s lives again.

FOOTNOTES:

  1. Aramwit, P. Bio-response to silk sericin. Chapter: 11. Kundu, S. In: Silk Biomaterials for tissue engineering and regenerative medicine.  Vol. 74. New Delhi: Woodhead Publishing; 2014:299-329.
  2. Aramwit, P. Siritientong T. and Srichana T. Potential applications of silk sericin, a natural protein from textile industry by-products. Waste Management & Research.  2012;30(3):217-224.