Super vision
Scientists have created nanoparticles that "taught" mice to see heat
Chinese biotechnologists have created nanoparticles that can connect with light-sensitive receptors of the eyes and convert infrared light into visible radiation. The results of the first experiments on mice were presented in the journal Cell (Ma et al., Mammalian Near-Infrared Image Vision through Injectable and Self-Powered Retinal Nanoantennae).
"We have shown that both rods and cones can connect with our nanoparticles, acquiring the ability to "see" infrared radiation in the near part of its spectrum. We believe that they are fully compatible with human eyes. This will not only help create "super vision", but also help color blind people who are unable to see red," said Tian Xue from Hefei University (in a press release Nanotechnology makes it possible for mice to see in infrared).
The eyes of humans and many other mammals contain two types of light–sensitive cells - cones and rods. Cones allow us to distinguish colors, but at the same time they work only at sufficiently high illumination, and sticks allow us to see silhouettes of objects in the dim light of stars or the Moon.
As experiments of recent years show, the number of different types of cones and their functions differ markedly in different groups and even genera of animals – for example, a person has three types of cones, and some species of birds and reptiles have four types, one of which allows them to see ultraviolet radiation.
Other animals, for example, mantis crayfish, have an even more exotic vision system containing 12 different photoreceptors, each of which distinguishes a certain color. Biologists and engineers have long been trying to copy these "inventions of nature" and teach animals to "see" other physical phenomena, for example, magnetic fields.
Xue and his colleagues eliminated one of the main shortcomings of the vision of all mammals – our inability to see thermal radiation, as do snakes and some invertebrates.
In recent years, as scientists have noticed, physicists have created many different nanoparticles capable of absorbing certain types of electromagnetic waves and converting them into other types of radiation. Many of them are now used in experiments to destroy cancerous tumors, during which these structures penetrate into the tissue and are then "fired" by an infrared laser.
Similar experiments have prompted Chinese biotechnologists to think that similar nanoparticles can be used to "teach" the eyes of humans and other mammals to see thermal radiation.
Guided by this idea, they created microscopic spheres made of compounds of rare earth metals, sodium and fluorine, capable of absorbing infrared rays with a wavelength of about 930 nanometers and converting them into green light. Then they coated these structures with a layer of polymers and proteins necessary for attachment to the shells of photoreceptors.
After testing their work on retinal cell cultures, the scientists injected a small number of similar nanoparticles into the eyes of mice and monitored how their behavior would change. As it turned out, rodents almost instantly learned to react to rays invisible to other animals and avoid those parts of the cells that were "illuminated" by IR lamps.
Subsequent experiments have shown that mice have learned to use their new ability to recognize thermal patterns on the walls of their cells, indicating the presence of food or danger. The rodents maintained "thermal vision" throughout the ten weeks of the experiment and did not experience any health problems.
In the near future, as Xue noted, his team will create safer versions of such nanoparticles that do not contain potentially toxic compounds of rare earth elements. They, as the researchers hope, will not only help a person learn to see in complete darkness, but also allow to cure many eye diseases.
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