Eye treatment extends the mouse’s sight beyond the visible spectrum

Tired of having to grab your night vision goggles when you want to track someone’s heat signature after dark? Well, biotechnology could one day come to the rescue of all the budding spies. Because the researchers developed a nano-scale injectable antenna, which they used to allow mice to see beyond their normal visual spectrum and into the infrared. The book appears in the newspaper Cell. [Yuqian Ma et al, Mammalian Near-Infrared Image Vision through Injectable and Self-Powered Retinal Nanoantennae]

Like all mammals, we humans can only see light in the visible spectrum, which includes all the colors of the rainbow. This limitation is due to the fact that the photoreceptors in our eyes are only able to detect radiation with a wavelength of around 400 to 700 nanometers. Which means we can’t see infrared and near infrared light, which has slightly longer wavelengths.

And that made scientists think.

“So we’re always curious as to whether we can use a method or technique to allow us to see near infrared light or infrared light. “

Tian Xue of the University of Science and Technology of China. He contacted his colleague Gang Han at the University of Massachusetts Medical School, who designed a tiny device, which he calls an “upconverting nanoparticle.”

[GH]: “We have actually developed nanoparticles, called upconverting nanoparticles, which can actually be activated by this near infrared light. “

Then they tested their system on mice. Nanoparticles attach to photoreceptors in the animal’s retina. There, they absorb infrared radiation and convert it into visible green light.

[GH]: “This green light is absorbed by the retinal cells.”

What the brain then interprets as normal visible light.

This enhanced super-vision allows animals to not only see in the infrared, but to discriminate between the different infrared models. So, for example, they could be taught to navigate to horizontal rather than vertical stripes, patterns that the researchers themselves could not see.

Even Xue found it a little baffling.

[TX]: “When we do the experiment it sometimes seems a little scary because if you don’t wear night vision goggles and when we do the tests we show the model to the animals, in fact in our own eyes we can’t not say near- infrared models, but the injected animal could. They can use models to guide their behaviors very precisely and effectively.

Han says the enhanced infrared detection doesn’t appear to interfere with or replace the animal’s standard visual abilities.

[GH]: “The treated mice were able to perceive these light patterns under daylight conditions, clearly suggesting that the nanoparticles also function in parallel with classical visible vision.”

The technology, in addition to its applications in the military or law enforcement, might even provide a possible solution to color blindness. And best of all, Xue notes, it wouldn’t need batteries.

[TX]: This new nanoparticle technique is stealthy and[es] no need for external power. Nanoparticles directly activated by infrared light itself.

The nanoparticles remained active for up to two months. A similar infrared boost could one day allow us humans to overcome our natural visual limitations. And see it in a whole new light.

—Karen Hopkin

(Text above is a transcript of this podcast)

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