Scientists have just discovered something like a superpower from experiments with mice. Using nanotechnology that converts infrared (IR) light into visible light, the researchers gave mice the ability to see in the dark. If the same technique works in humans, it could provide night vision without goggles and possibly combat vision-related diseases.

Nanotechnology gives humans the ability to see in the dark

When injected into the eye, the nanoparticles provide visible light to the sensitive pigments for the vertebrates to see. The pigment is located in specialized cells called photoreceptors, located in the retina at the back of the eye. The combination of pigments in these photoreceptors absorb different colors of light, triggering nerve impulses that travel through the optic nerve to the visual centers of the brain. Humans have three pigments that help us see colors and another that helps us see black and white, especially in dim light. Rats and some primates have only two color pigments and one for dim light.

Researchers have previously added the gene for the third pigment to mice and primates to give them a range of human-like sensitivities to light. But so far, no mammal has been able to see IR light under normal conditions.

Research process

To change that, Xue Tian, ​​a visual physiology specialist at the University of Science and Technology of China, teamed up with Gang Han, a nanoparticle specialist at the University of Massachusetts Medical School in Worcester . Han has previously developed nanotechnology that can convert IR to blue light. Because blue light carries more energy than IR, these so-called switching nanoparticles (UCNPs) must absorb many IR photons before they release a single blue photon. That led Han and Xue to wonder if such nanoparticles on the photoreceptor would convert enough IR into visible light to allow mice to see in the dark.

To find the cause, Han and colleagues first improved the animals’ chances: They tuned the UCNPs to emit green light. (Animal green photoreceptors are more sensitive than blue.) They then coated their UCNPs with a protein that binds to specific sugar molecules on the membranes of the receptor cells. the light. After injecting these substances into the posterior retinas of mice, they found that the UCNPs bind tightly to the photoreceptors and stay there for up to 10 weeks with no apparent lingering side effects.

Experiments were carried out on mice and the results were as expected.

And the nanoparticle injection seems to have brought about the desired effect. The mice that received them showed physical signs of detecting IR light and converting it to visible light. Electrophysiological recordings also showed that IR light triggered neural responses in the retina and visual cortex in the mice implanted with the nanoparticles.

Finally, Xue, Han and their colleagues ran mice through behavioral tests to determine whether the animals with the nanoparticles saw a diffuse haze or were able to recognize patterns. special form and pattern or not. In one test, they swam in a water maze with no exit. On the wall above one route, the researchers projected a triangle and on the other wall, a circle. Below the triangle, the researchers placed a sunken platform so the animals could climb to escape the water.

When the shapes were illuminated with visible light, all the animals quickly learned to associate the comfort of the pedestal with the triangle and immediately swam towards it, even when the researchers Swap the positions of triangles and circles.

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