Mice given ‘night vision’ by injecting nanoparticles into their eyes
Ever wanted to see in the dark? We might be a step closer, in light of a study that shows mice can be given infrared “night vision” for up to 10 weeks through a simple injection, and with negligible side effects.
This could serve as the basis for human “super vision” as well as fixing red colour blindness, said senior author Tian Xue at the University of Science and Technology of China in a statement.
The nanotechnology works by binding with the retinal cells in the eye that convert light into electric signals.
Like humans, mice cannot perceive light with a wavelength longer than 700 nanometres, which is at the red end of the visible spectrum. But the nanoparticles absorb light with longer – infrared – wavelengths and convert it into shorter wave light that retinal cells can detect. This converted light peaks at a wavelength of 535 nanometres, so the mice see infrared light as green.
To probe the limits of this infrared perception, Xue and his colleagues performed a suite of tests on the mice.
One involved shining infrared light into their eyes. The pupils of mice given the nanoparticle injection contracted, whereas those injected with an inert, control solution were unaffected. The retina and visual cortex also activated in response to infrared light in the mice with the nanoparticles.
Current infrared technology, which allows the wearer to see heat emitted from objects or animals, is often hampered by bulky batteries and interference from visible light.
But water maze tests demonstrated that the treated mice could distinguish infrared patterns while also exposed to daylight.
In fact, mice taught that a certain infrared pattern led to a submerged platform in the water used the same rule when the pattern was displayed in the visible light range. This suggests the mice perceived the infrared and visible light similarly, the researchers write.
Some mice did develop cloudy corneas after the injection, but this disappeared within a fortnight and occurred at similar rates to those in the control group. The team found no other evidence of damage to the mice’s eyes two months after the experiment.
Journal reference: Cell, DOI: 10.1016/j.cell.2019.01.038