- Researchers injected nanoparticles in mice’s eye to make them see and respond to infrared light.
- The technology has minimal side effects, and could be adopted for human eyes in the near future.
The human visual system is capable of detecting light between 400 and 700 nanometers, called visible light. However, the detection of longer wavelength light — near-infrared light — is a tough challenge for mammals.
Now, a team of international researchers has used nanotechnology to enhance the mice vision so that they can see both visible and infrared light. They injected certain nanoparticles in the mice’s eyes whose effect lasted up to 10 weeks, enabling them to see infrared light with enough specificity to differentiate between several shapes.
The side effect of this injection was very minimal: in rare cases, mice developed cloudy corneas, which disappeared within 7 days. Other than this, the team found no damage to the structure or shape of the retina.
What Exactly They Did?
When light enters our eye, the photoreceptor cells in the retina — a specialized type of neuroepithelial cell capable of visual phototransduction — absorb the photons with visible light and transmit relative electric signals to the brain. But since these cells do not absorb longer infrared wavelengths, our eyes are incapable of perceiving infrared light.
In this work, researchers created nanoparticles that attach with photoreceptor cells and behave as infrared light transducers. These nanoparticles are capable of capturing longer infrared wavelengths and emitting shorter light wavelengths.
Reference: Cell Press | doi:10.1016/j.cell.2019.01.038
They do the same when infrared light enters the retina: they make photoreceptor cells absorb shorter wavelengths and transmit a usual electric signal to the brain, as if visible light had entered the eye.
The image represents how injectable nanoparticles enable mice to develop infrared vision without degrading their normal vision | Courtesy of researchers
In this study, researchers found that nanoparticles were able to absorb infrared light 980 nanometers in wavelength and transform it into a wavelength of 535 nanometers, making infrared light appear as the green color.
The team injected these nanoparticles in mice and set up a course of maze tasks to test whether mice could see or respond to the infrared light. As expected, mice responded well to both infrared and visible light in daylight conditions.
What About Human Eye?
According to the researchers, their technology could be adapted for human eyes as well. Along with providing supervision, it could offer curative solutions for red color vision deficits in human eyes.
The technology could be useful for various infrared applications in civilian encryption and military operations. It can be further improved by integrating new organic-based nanoparticles that may yield even brighter infrared vision.