Nanoparticle eye drops give mice night vision

Pablo Tucker
March 4, 2019

It works by converting the light into shorter wavelengths at the green end of the spectrum so the mice see infrared light as green, similar to night vision goggles.

Researchers from the University of Science and Technology, China, and the University of Massachusetts Medical School (UMass) in the USA, injected the rodents' eyes with a solution filled with nanoparticles.

The Chinese scientists behind the work said that it could pave the way for soldiers to be given "super vision" and help to treat forms of colour-blindness. These findings could lead to advancements in human infrared vision technologies, including potential applications in civilian encryption, security, and military operations.

Prof Gang Han, a biochemist at the University of Massachusetts Medical School, explained: "When light enters the eye and hits the retina, the rods and cones - or photoreceptor cells - absorb the photons with visible light wavelengths and send corresponding electric signals to the brain". But infrared radiation, which has a longer wavelength, is all around us.

By the way, near-infrared light appeared green to the mice.

To test how well the nanoparticles worked, the researchers carried out a number of experiments to determine if the eyes of the mice were picking up infrared light.

Scientists from the University of Massachusetts Medical School and the University of Science and Technology of China have reportedly teamed up and developed technology that gives the ability of night vision to the mammal eye, allowing it to see beyond the visible spectrum and into the infrared region. Wavelengths longer than 700 nanometers are invisible to us and are designated as "infrared" (and even longer wavelengths are things like microwaves and radio waves, which we certainly can not see). The particles were created to absorb the longer IR wavelengths and emit the shorter visible wavelengths, which are in turn absorbed by photoreceptor cells that signal the brain. Mice that were injected with the nanoparticles showed unconscious physical reactions to infrared light detection, while those that received only a buffer solution couldn't see the infrared light.

In rare cases, side effects from the injections such as cloudy corneas occurred but disappeared within less than a week.

"We have shown that both rods and cones bind these nanoparticles and were activated by the near infrared light", Xue said. Tests showed that the mice experience no retinal damage due to the injections.

Prof Han said: "In the future, we think there may be room to improve the technology with a new version of organic-based nanoparticles, made of FDA (Food and Drug Administration) approved compounds, that appear to result in even brighter infrared vision". Once those particles were in a mouse's eye, the proteins guided them to photoreceptor cells in the retina, essentially glueing the particles to those cells.

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