Using spider silk to detect molecules

January 13, 2016 by Emmanuel Barraud, Ecole Polytechnique Federale de Lausanne
Using spider silk to detect molecules

At EPFL, fiber optics specialists have discovered some unique qualities of spider silk when it comes to conducting light and reacting to certain substances.

"It's unexpected and extremely promising!" Luc Thévenaz, the professor in charge of EPFL's Group for Fibre Optics, recently experienced a eureka moment in his research. Picking up on an idea proposed by a discussion group of the European Space Agency, he shifted his attention away from traditional fibers made of glass and focused on the silk strands that spiders produce for their webs. These strands are perfectly cylindrical, smooth, transparent and extremely solid – some of the same characteristics as glass-based fibers.

But there is one major difference: while glass is inert, is made up of very long proteins rolled into a helix structure whose bonds are sensitive to a number of chemical substances.

Reusable chemical sensors

"The helix in the silk strands unwinds whenever polar molecules like acetic acid and ammonia come into contact with its bonds," said Dr. Thévenaz. "This measurably modifies the way the strands conduct light, and it gave us the idea of using them to make ."

The researchers discovered another remarkable property, that the change in the helix structure was completely reversible. A sensor using spider silk could thus be used several times over. "We are looking at the possibility of creating silks by adding molecules meant to react with the substances to be tested. That is often impossible with glass fibers, which we have to heat to more than 1,000°C in order to stretch," said the researcher. Also, because silk is biodegradable, it is ideal for sensors that could be implanted in a living body without needing to be removed later on.

Spiders at work

At EPFL, doctoral student Desmond Chow and post-doc Kenny Hey Tow are working on natural silk strands with a diameter of 5 microns. They were produced by Australian Nephila edulis spiders grown at the Department of Zoology of the University of Oxford. Synthetic silks exist, but they are expensive and do not work as well as real ones.

The researchers stretch a silk strand taut in a tiny bracket and direct a laser beam at one end of the strand. At the other end, a polarization analyzer is used to measure infinitesimal changes in the light passing through it. If a gas that interacts with the silk strand is present, the device will pick up on this immediately.

This research is still in the early stages, but it is already firing the imagination of the fiber optics specialist. "We have presented it at several conferences, where it was met with significant interest," he said. The study is in the running for research funds. "We are entering a totally new domain that has yet to be explored," said Dr. Thévenaz.

Explore further: Spiders sprayed with carbon nanotubes spin superstrong webs

Related Stories

Spiders sprayed with carbon nanotubes spin superstrong webs

May 6, 2015

(Phys.org)—A team of researchers working in Italy has found that simply spraying a spider with a carbon nanotube solution can cause the spider to spin stronger webs. In their paper they have uploaded to the preprint server ...

Silkworms spinning spider webs

January 3, 2012

(PhysOrg.com) -- A spiders silk is strong and more elastic and has a large range of possible medical applications. However, spiders have a history of being territorial and prone to cannibalism, so the idea of having a large ...

Recommended for you

New fuel cell technology runs on solid carbon

January 22, 2018

Advancements in a fuel cell technology powered by solid carbon could make electricity generation from resources such as coal and biomass cleaner and more efficient, according to a new paper published by Idaho National Laboratory ...

Bio-renewable process could help 'green' plastic

January 19, 2018

When John Wesley Hyatt patented the first industrial plastic in 1869, his intention was to create an alternative to the elephant tusk ivory used to make piano keys. But this early plastic also sparked a revolution in the ...

Simulations show how atoms behave inside self-healing cement

January 19, 2018

Researchers at Pacific Northwest National Laboratory (PNNL) have developed a self-healing cement that could repair itself in as little as a few hours. Wellbore cement for geothermal applications has a life-span of only 30 ...

Looking to the sun to create hydrogen fuel

January 18, 2018

When Lawrence Livermore scientist Tadashi Ogitsu leased a hydrogen fuel-cell car in 2017, he knew that his daily commute would change forever. There are no greenhouse gases that come out of the tailpipe, just a bit of water ...

A new polymer raises the bar for lithium-sulfur batteries

January 18, 2018

Lithium-sulfur batteries are promising candidates for replacing common lithium-ion batteries in electric vehicles since they are cheaper, weigh less, and can store nearly double the energy for the same mass. However, lithium-sulfur ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Chem
not rated yet Jan 16, 2016
Good Discovery, appreciated

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.