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Innovation

Nano-optical switches to restore sight?

Californian researchers are using light to control biological nanomolecules and proteins. They think it's possible to put some of their nano-photoswitches in the cells of the retina, restoring light sensitivity in people with degenerative blindness such as macular degeneration.' It will be a long time before this comes out of the lab...
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Written by Roland Piquepaille, Inactive on

Californian researchers are now using light to control biological nanomolecules and proteins. They think it can help them to develop treatments for eye diseases, such as the loss of the light detectors in the retina which is a major cause of blindness. So they envision to put some of their nano-photoswitches in the cells of the retina, 'restoring light sensitivity in people with degenerative blindness such as macular degeneration.' It will be a long time before this comes out of the lab, but read more...

This research is being done at the University of California at Berkeley and involves several professors and their labs, including Ehud Isacoff, Richard Kramer, Dirk Trauner and John Flannery.

And here is a short explanation of what they did.

The development involves altering an ion channel commonly found in nerve cells so that the channel turns the cell on when zapped by green light and turns the cell off when hit by ultraviolet light. The researchers demonstrated in 2004 that they could turn cultured nerve cells on and off with this optical switch. Since then, [...,] they've injected photoswitches into the eyes of rats that have a disease that kills their rods and cones, and have restored some light sensitivity to the remaining retinal cells.

Apparently, you can do many things with these photoswitches. Here are two examples below (Credit for image and caption: UC Berkeley). "At top, it can be used to stuff a molecule into the active site of an enzyme, either activating or inactivating the enzyme. At bottom, it can be used to force two molecules together, like a nanotweezer. Different colors of light force these transitions: light with a wavelength of 500 nanometers (green) kinks the molecule; 380 nanometer-wavelength light (ultraviolet) unkinks it."

A light-activated nanotweezer diagram

Now, what will this research drive to?

"The research will focus on one major application: restoring the response to light in the eyes of people who have lost their photoreceptor cells, in particular, the rods and cones in the most sensitive part of the retina," Isacoff said. "We plan to develop the tools to create a new layer of optically active cells for the retina."

And the researchers have even more ambitious goals for the future. If it's possible to stimulate a nerve cell, it should also be possible to develop treatments for other diseases. But don't you think they should focus on retina reactivation for the moment?

For more technical information, the researchers have already described a re-engineered glutamate receptor sensitive to light in an article published by Nature Chemical Biology under the name "Allosteric control of an ionotropic glutamate receptor with an optical switch" (Volume 2, Number 1, Pages 47-52, January 2006). Here are two links to the abstract and to the full paper (PDF format, 6 pages, 359 KB).

Sources: Robert Sanders, UC Berkeley News, via EurekAlert!, October 31, 2006; and various websites

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