The Power of Silk
An age-old material offers tantalizing solutions to a range of contemporary problems
For 5,000 years, humans have hijacked the fibers the little silkworm needs for its cocoon to produce fine textiles. Before spinning it into its familiar fibrous form, the worm stores its silk in a liquid solution in its body. Fiorenzo Omenetto, a bioengineer who works with lasers and fiber optics, was intrigued by silk’s transition from liquid to solid.
“To me, it was similar to the way glass is made into optical fiber,” he said. “We can take this manufacturing process and hack it.”
Omenetto, the Frank C. Doble Professor of Engineering and associate dean for research at Tufts School of Engineering, gave the keynote address at the 2016 edition of Bates-Andrews Day, the dental school’s annual student research symposium.
A Magical Solution
Describing myriad projects underway in his lab—“It’s a bit of a laundry list,” he said—Omenetto said the dizzying array of sci-fi-sounding solutions to many of our problems rest on the malleability of the silk protein. His research team manipulates silk’s molecular structure as it changes from its liquid state into a solid. The scientists can produce liquids of varying viscosities, or clear plastic-like sheets, or prism shapes that reflect light.
“If you have access to the magical solution that the [silkworm] has, then you can morph it into many different shapes relevant to technology today,” he said. “That’s the beauty of bottom-up assembly.”
Among the projects his team is working on is an implantable chip that can be switched on and off via an external remote control, like a cell phone. Left in a patient after surgery, the chip can be activated to heat up after an operation, killing off localized bacterial infection and eliminating the need for antibiotics. His lab is also looking at how implantable silk-based devices in the form of reflective prisms could deliver chemotherapy drugs and, via optics, report back on how much of the drug remains in the device.
“Light comes in and is bounced back by faces of the prism,” he said. “As the drug is delivered, the reflectivity changes, and there’s a correlation between the amount of drug released and a change in reflectivity. So it’s a nice way to monitor what is happening,” he said. This tightly controlled drug-delivery could change the way chemotherapy is given or potentially open up new forms of treatment that respond to conditions within the body.
“If you have access to the magical solution that the [silkworm] has, then you can morph it into many different shapes relevant to technology.”
Diaphanous and pliant, silk is also remarkably strong, able to support one-third as much as steel. It’s also nontoxic and biocompatible. “Cells like interfacing with it,” he said.
Omenetto and his colleagues have produced silk-based inks and circuitry that can sense the presence of bacteria. Most interesting to the dentists in the room, these tiny sensors could be “tattooed” on teeth to provide information about levels of bacteria in the mouth—information that would help determine treatment protocols for periodontitis, for example. The biodegradable inks and circuits can also be embedded in materials like surgical gloves or stuck onto foods, ensuring that doctors and diners alike are aware of the presence of deadly microbes.
Speaking of foods, the researchers are also working on a silk-based coating for perishable foods. By locking oxygen away from fruits and veggies, the coating could keep them fresher at room temperature for much longer. Omenetto and his team are looking into similar technology to help stabilize vaccines, which typically depend on refrigeration to remain active—something that can be hard to come by in developing countries where vaccines are often most needed. Similar technology could be used to stabilize blood for easier transport and testing.
Silk’s potential could extend beyond biomedical applications, Omenetto said. Because the material dissolves in water and is absorbed easily by living organisms, silk devices can be programmed to dissolve once they’ve served their purpose, he said, showing a video of a model plane with silk-based wings dissipating in water after a test flight.
But these sustainable materials will not be widely accepted unless they perform at least as well as the less-green ones in our devices today, Omenetto said. “We are taking small steps towards what could be done in this arena. I hope I gave you some ideas,” he told the dentists. “You can start working with this unusual interface as well.”
Talking Back at Bates Day
Bates Day is a Tufts tradition that dates back to 1930, but this year, a new technology marked the transition of the annual student science forum into the 21st century. Known as Bring Your Own Device (BYOD) Peer Review, the new twist allowed students and visitors viewing the student posters and other projects on display to offer real-time feedback via their cell phone, tablet or computer.
All presenters were provided with an individual web address and QR code—a scannable square code akin to a supermarket barcode—that they could display on their posters. Visitors to the poster were able to type in the web address or scan the QR code to access a survey specific to the presentation and provide immediate feedback. Presenters were able to access the surveys immediately after Bates Day.
“Large numbers of people are moving through the exhibits, and it can be hard to engage with students directly and difficult to ask questions and give feedback,” says Jennipher Murphy, education technology senior administrator at the School of Dental Medicine. “BYOD gives visitors the opportunity to reflect on the presentation and to give immediate, meaningful feedback to the student. It can also motivate people who might be hesitant to give feedback face-to-face.”
With meetings of the American Dental Education Association and International Association of Dental Research just days away, student presenters were eager for input. Mansi Jailwala, D17, said a lot of people who stopped by her poster used the new technology. Her project surveyed her classmates about their experiences with and attitudes about domestic violence as well as its role in the dental curriculum. Shawheen Saffari, D16, who worked with a number of collaborators said practicing before a friendly crowd is the best way to make sure he speaks as eloquently as possible for the whole group. “Constructive feedback is always welcome,” he said. –Jacqueline Mitchell