Scientists have taken a big step forward to inject eyes with night vision



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An incredible new nanotechnology could one day allow us to see in the dark. It works on mice, and nothing says that it would not be as effective on other mammals. The only drawback – how are you with the needles to the eyeball?

Research conducted by the China University of Science and Technology has produced particles that adhere to light-detecting cells in the retina and help them respond to near-infrared (NIR) wavelengths. .

The back of our eye, where the retina is located, acts as an inverted television screen. While the full spectrum of light falls on its cells, certain wavelengths trigger chemical reactions that we perceive either in color or in intensity.

The rod-shaped cells tell our brain how bright it is. They react strongly to light waves with a size of about 500 nanometers, but struggle to react beyond 640 nanometers, well in the red part of the spectrum.

We also have three types of conical photoreceptor cells cone-shaped, each sensitive to its own parts of the spectrum. Together, they provide our brain with the detail needed to distinguish colors.

But these cones also do not detect light greater than 700 nanometers, which means that anything above the red part of the spectrum is totally invisible to us.

It's a shame. For us, darkness is often washed in low-energy, low-wavelength portions of the spectrum. A number of animals, such as snakes and frogs, have come up with methods to exploit these wavelengths to track their prey or better see the night.

Unfortunately, mammals have never managed to evolve what it takes to even see the edge of this infrared spectrum. We humans are relatively lucky. The mice only have rods and two types of conical cells, all of which end at slightly shorter wavelengths than ours.

There are chemistry quirks that can help us glimpse a flash of NIR light, but in general, an infrared landscape is strictly forbidden to us, human beings.

Large night vision goggles can capture this radiation and amplify it at visible wavelengths, but wearing this technology is bulky and can not be used in daylight.

The nanoparticles developed by the researchers of this latest innovation behave like miniature night vision devices. Only these rely directly on light-sensitive cells.

Called photoreceptor-binding up-converting nanoparticles, they are a protein designed to adhere to rod and cone photoreceptors and transform long wavelengths into shorter ones.

The result is a nanoscale device that acts as a tiny antenna, absorbing invisible NIR radiation and transforming it into a color more likely to trigger stems and cones in action, painting the world in shades of green. .

Injected to mice, the whole process seems to work brilliantly. Nanoantennae have been shown to not only stick to photoreceptors, but a weakly brilliant LED at 980 nanometers induces retinal responses that affect the visual cortex of the brain.

In a more practical experiment, the treated mice were able to differentiate simple shapes such as triangles and circles illuminated by the LED under various conditions. Better still, they were still able to see very well under normal daylight conditions.

The change of vision did not have any terrible side effects either. The only problem the team found was cloudiness in the eyes of the mice.

The visual system of the mouse is sufficiently similar to that of humans so that we can expect that a version of this method will work for us as well. In fact, there is even some kind of strange precedent.

A few years ago, biohackers developed a similar process using a light-sensitive substance called Chlorine e6 to make the retina generally more sensitive to light. Applied as eye drops, subjects may see longer distances in low light conditions.

The question of whether this promises true technology or whether it is simply an overexcited experience is debatable. Eye drops would certainly be better than an injection into the eyeball, but this new nanotechnology relies on much more rigorous scientific basis.

It is not difficult to find interesting uses for such technology. Military applications aside, who would not want to see better at night? Astronomers, for one.

"We can have the ability to visualize all the hidden information of the NIR and IR rays in the Universe, which are invisible to our bare eyes," says biochemist Gang Han of the University of Medicine's Faculty of Medicine. Massachusetts.

But there are also serious benefits for research in the form of experimental tools to study visual processes at new levels.

"Through this research, we have broadened the applications of our nanoparticle technology, both in the lab and in translation," Han said.

"These nanoantennae will allow scientists to explore a number of fascinating questions, ranging from how the brain interprets visual cues to the treatment of color blindness."

This research was published in Cell.

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