Scientists give mice infrared vision, turning them into tiny Predators

Pop culture is full of superheroes and villains that can see their worlds in infrared. Superman can do it. So can the fearsome Predator. Sadly for us, the ability has remained confined to comics and film. Yes, the human eye is a marvel in itself, but the ability to see beyond the visible spectrum is just not within its capabilities.

However, a group of Chinese scientists might have just changed that, creating an injectable nanoparticle that provides superhuman vision.

Researchers from the University of Science and Technology of China and the University of Massachusetts Medical School developed an "ocular nanoparticle" that can detect near-infrared light (NIR). They then injected it directly into the eyes of mice. Their study, published in Cell on Feb. 28, shows that the mice were given "super vision", allowing them to see beyond the visible spectrum, without any effects on their regular vision.

Essentially, they created a Supermouse. This is its origin story -- and no, it (sadly) does not involve any radioactive spiders.

Mouse eyes, like human eyes, are limited to seeing "visible light", which makes up just a tiny portion of the electromagnetic spectrum. Typically, our eyes only respond to wavelengths in the spectrum between approximately 400 and 700 nanometers. 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 cannot see).

To enable the mouse eye to see in infrared, the research team developed a nanoparticle that would shift the wavelength of incoming infrared light (at 980 nanometers) to a wavelength that was detectable by the cells in the eye (535 nanometers). The nanoparticle is so tiny that it can be injected into the inner eye where it attaches to the retinal cells -- those responsible for converting light to electric signals that can be interpreted by the brain. And by shifting the wavelength down to 535 nanometers, the mouse eye should be able to detect the once-invisible infrared light as a green glow. 

The researchers tested if the mouse could detect the light by assessing their pupils. When exposed to light, mouse (and human) pupils contract to regulate how much light is passing into the eye. If the nanoparticles were working, the scientists should be able to shine the invisible infrared light into the eye and still see the pupils contract. 

And that's exactly what happened. Supermouse was born.

Not only that, but the team ran the mice through a series of water Y-mazes in an effort to determine whether they could make out visual patterns in infrared light to find a hidden platform. They trained the mice to associate an infrared light pattern with the platform and then tested both injected mice and non-injected mice to see how they fared.

Mice that did not receive the ocular injections only correctly found the platform 50 percent of the time, but those with the nanoparticles lurking in their eyes were able to do so around 80 percent of the time even in the dark. Moreover, the nanoparticles continued to work for up to 10 weeks without any residual side effects or long-term damage to normal vision. 

Because the new technology is compatible with regular vision, it could provide a new way for mammalian vision enhancement or even open up new avenues to repair normal vision -- you could tinker with the nanoparticles so they parse different wavelengths or alter them enough that they deliver drugs into the eye. 

This isn't a blink and you'll miss it technology either -- there's still a ways to go before we obtain comic book hero levels of infrared vision. The nanoparticles used in this study only pick up a very specific infrared wavelength -- anything outside this would remain invisible. 

But hey, it's still a pretty good origin story. I'm keen for the sequel.