Using water molecules to read electrical activity in lipid membranes

EPFL researchers were able to map out in real time how charges are transported across and along membranes simply by observing the behavior of adjacent water molecules. Credit: Jamani Caillet/EPFL

Researchers from the Laboratory for fundamental BioPhotonics (LBP) in EPFL's School of Engineering were able to track these moving charges in real time in a completely non-invasive manner. Rather than observing the membranes themselves, they looked at the surrounding water molecules, which, in addition to keeping the membrane intact, change orientation in the presence of electrical charges. So by 'reading' their position, the researchers were able to create a dynamic map of how charges are transported across a membrane.

The researchers' method has just been published in the journal Proceedings of the National Academy of Sciences (PNAS). It could shed light on how ion channels function, along with other processes at work in membranes. This clinically viable method could potentially also be used to directly track ion activity in neurons, which would deepen researchers' knowledge of how nerve cells work. “Water molecules can be found wherever there are lipid membranes, which need these molecules to exist,” says Sylvie Roke, head of the LBP. “But until now, most studies on membranes didn't look at these molecules. We've shown that they contain important information.”

The researchers did this by using a unique second-harmonic microscope that was invented at the LBP. The imaging efficiency of this microscope is more than three orders of magnitude greater than that of existing second-harmonic microscopes. With this microscope, the researchers obtained images of water molecules at a time scale of 100 milliseconds.

To probe the lipid membranes' hydration, the researchers combine two lasers of the same frequency (femtosecond pulses) in a process that generates photons with a different frequency: this is known as second-harmonic light. It is generated only at interfaces and reveals information on the orientation of water molecules. “We can observe what's happening in situ, and we don't need to modify the environment or use bulky markers like fluorophores that would disturb water molecules' movement” says Orly Tarun, the publication's lead author.

Unexpected charge fluctuations are observed

With this method, the researchers observed charge fluctuations in membranes. Such fluctuations were previously unknown and hint at much more complex chemical and physical behavior than is currently considered.

###

Reference: O. Tarun, C. Hannesschläger, P. Pohl, and S. Roke, A label-free and charge-sensitive dynamic imaging of lipid membrane hydration on millisecond time scales, PNAS

Laboratory of fundamental BioPhotonics (LBP) – Julia Jacobi Chair of Photomedicine

Media Contact

Sylvie Roke
sylvie.roke@epfl.ch
41-216-931-191

 @EPFL_en

http://www.epfl.ch/index.en.html 

Media Contact

Sylvie Roke EurekAlert!

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Lighting up the future

New multidisciplinary research from the University of St Andrews could lead to more efficient televisions, computer screens and lighting. Researchers at the Organic Semiconductor Centre in the School of Physics and…

Researchers crack sugarcane’s complex genetic code

Sweet success: Scientists created a highly accurate reference genome for one of the most important modern crops and found a rare example of how genes confer disease resistance in plants….

Evolution of the most powerful ocean current on Earth

The Antarctic Circumpolar Current plays an important part in global overturning circulation, the exchange of heat and CO2 between the ocean and atmosphere, and the stability of Antarctica’s ice sheets….

Partners & Sponsors