Stabilized, purified silk protein serves as green chemistry platform

Scientists have long sought ways to take advantage of the high strength of natural silk protein in new materials, but its incorporation has been hindered by the inability to stabilize the protein in water. Now, a company known as Evolved By Nature (EBN; Boston, Mass.; www.evolvedbynature.com) has developed a process to purify and solubilize silk protein, allowing its use as a starting material for a host of different silk-based materials from the same chemistry platform.

EBN envisions the silk protein platform as a way to replace petroleum-based chemicals with environmentally friendly and better-performing materials. For example, EBN CEO Greg Altman says biodegradable silk can replace finishing compounds for textiles, replace synthetic emulsifiers and other additives in cosmetic products, and coat fabric in performance apparel.

The process to make what EBN calls Activated Silk begins with waste cocoons from silkworms in the natural silk fabric industry. The cocoons are subjected to an extraction process to separate two components of the silk — sericin and fibroin. The fibroin is dissolved in a specially developed salt solution that reversibly interrupts the hydrogen bonds that are present in the amino acid beta sheets (a common protein motif) of the silk protein. The solution then goes through a diafiltration process to remove the salt, leaving a silk protein dissolved in aqueous solution. The solubilized silk can then be used to bind with other molecules or polymers.

In bringing its Activated Silk to market, Evolved By Nature is pursuing two commercial markets initially: textile finishing and cosmetics. Altman plans for the company to expand into other areas in the near future. “There are over 75 unique molecular configurations for natural silk protein,” he says, “so we can manipulate the silk polymer to do a wide variety of things.”