Discovery Files

Scientists use modified silk proteins to create new nonstick surfaces

Chemical modification of silk proteins makes them repel water better than available nonstick coatings

Researchers at Tufts University have developed a method to make silk-based materials that refuse to stick to water, or almost anything else containing water. In fact, the modified silk, which can be molded into forms like plastic or coated onto surfaces as a film, has nonstick properties that surpass those used on cookware. The material could see applications in consumer products as well as medicine.

Silk is a natural fiber spun by moths and has been used for thousands of years to make durable and fine fabrics — and surgical sutures to close wounds.

More recently, scientists have learned to break down the fibers to their basic protein element — silk fibroin — and reconstitute it into gels, films, sponges and other forms to create everything from implantable orthopedic screws to textile inks that change color in response to body chemistry.

The work is reported in the journal ChemBioChem. The U.S. National Science Foundation provided support though the Center for Nanoscale Systems at Harvard University.

Turning silk into a water repellant material involved covering the surface of the silk fibroin with short chemical chains containing carbon and fluorine, called perfluorocarbons. These chains are very stable and do not react with other chemicals, nor do they interact with proteins and other biological chemicals in the body.

While the natural surface of the silk protein acts like a magnet to water, with negatively and positively charged branches on the silk attracting water, a silk protein covered with perfluorocarbons leaves little for the water to grab on to.

It's not just water that rolls off the nonstick silk, but any substance that has water as a major component, which could include various foods, blood, cells and tissues.

The advantages of highly nonstick surfaces go well beyond medical applications. While there is concern about chemicals absorbed in the body from commercially available nonstick coatings, silk-based nonstick surfaces may offer an alternative option which can be explored for its relative safety.