Vision is essential for humans, with mammals able to detect visible light between 400 and 700 nm on the electromagnetic spectrum. In mammalian photoreceptor cells, light-absorbing pigments, consisting of opsins and retinals, are known as photon detectors. However, the detection of longer wavelength light, such as near-infrared (NIR) light, though a desirable ability, is a formidable challenge for mammals because detecting longer wavelength light, with lower energy photons, requires opsins to have much lower energy barriers. Now, a study from researchers at UMass Medical School develops an augmented injection containing nanoantennae to give night vision to mammals, allowing the animals to see in the range of infrared light. The team states their temporary vision augmentation opens translational opportunities for exploring neural networks in the brain and assisting with vision repair. The opensource study is published in the journal Cell.
Previous studies show the visible spectrum is a small portion of the electromagnetic spectrum observed by the human eye. The detection of longer wavelength light, such as NIR light or infrared light, is impossible. The human eye is unable to see NIR or to project a NIR image to the brain without the aid of complicated and cumbersome electronic devices, such as night-vision goggles which become saturated and lose their ability to function during the day. The current study develops an injectable, self-powered, built-in NIR light nanoantenna which can extend the mammalian visual spectrum to the NIR range.
The current study develops a lectin protein in the form of a nanoparticle that can be delivered in liquid. Results show these proteins guide the nanoantennae and glue them to the outside of retinal photoreceptors in mice. Once anchored on the cells, these microscopic antennae convert NIR into visible, green light. Data findings show the green light is observed by the retinal cell and images are sent and interpreted by the brain as visible light, without the aid of complicated equipment; after two weeks, the ability wore off and the nanoparticles left no adverse effects to the mice or their vision.
The lab states they demonstrated mice injected with these nanoantennae can perceive NIR light, obtain NIR pattern vision, and can differentiate between sophisticated shape patterns such as triangles and circles. Results show the treated mice were able to perceive these light patterns even in daylight conditions, indicating the nanoparticles were working in parallel with conventional vision. Data findings show due to the close proximity of the nanoantennae and photoreceptors, an exceptionally low power NIR LED lamp light is sufficient to activate the nanoparticles.
The team surmises they have developed a short-term augmented injection enabing mice to see in the infrared spectrum, giving them night vision. For the future, the researchers state their results could pave the way to numerous critical applications via mammalian NIR visual ability with the potential to view hidden information from NIR and IR radiation in the universe which is invisible to the naked eye.
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