Scientists at the cutting edge of nanotechnology are on the path to the seemingly impossible: creating an injection that allows us to see in the dark. This research opens the door to brand new therapeutic interventions.

The mammalian eye can only respond to a small band of wavelengths.

Generally, the range is 400–700 nanometers. Of course, the full spectrum of light is much broader.

At the longer end of this spectrum is near infrared (NIR) and infrared light (IR).

No mammals can detect these types of light.

Night vision goggles allow the user to detect these otherwise-invisible wavelengths, but they are cumbersome. Also, during daytime conditions, they become saturated with light and no longer function properly.

Recently, researchers at the University of Science and Technology of China and the University of Massachusetts Medical School in Boston started looking for ways to boost vision in mammals at NIR wavelengths without the need for wearable technology.

Integrating nanotech and vision

The work forms part of a new wave of research focused on integrating nanoparticles with biological systems. By inserting minuscule sensors or devices into living tissue, it might be possible to impart useful new capabilities.

Modern medicine is already finding uses for this. In one review, the authors explain, "There are now many prominent examples of nanomaterials being used to improve human health, in areas ranging from imaging and diagnostics to therapeutics and regenerative medicine."

The most recent investigation appears in the journal Cell. Gang Han, Ph.D. — who is an associate professor of biochemistry and molecular pharmacology — led the scientists.

In their paper, the scientists explain how they injected "photoreceptor-binding upconversion nanoparticles" into mice, which allowed the animals to see in the dark.

More specifically, they used a subretinal injection technique, which many ophthalmologists now commonly use.

The innovative experiments involved "gluing" so-called nanoantennae to the retinal photoreceptors of mice. Once there, the nanoantennae converted NIR light into visible green light. So, without the need for any external equipment, the rodents were able to perceive NIR light.

The team used lectin nanoparticles to shepherd the nanoantennaes into place.

A new way to approach vision

By putting the mice through a series of tests, the team proved that the animals could distinguish complex patterns in NIR light.

Also, because the nanoantennae were positioned so closely to the photoreceptors, only very low levels of NIR light were needed to trigger the nanoparticles, thereby allowing light perception.

Importantly, this did not affect the animals' daylight vision.

After around 2 weeks, their ability to see in the dark wore off. The mice appeared to experience no adverse effects, such as inflammation or cell death. Of course, the findings are fascinating, but the implications extend beyond general intrigue.

"These nanoantennae will allow scientists to explore a number of intriguing questions, from how the brain interprets visual signals to helping treat color blindness."

Gang Han, Ph.D.

According to the authors, "Endowing mammals with NIR vision capacity could also pave the way for critical civilian and military applications."

Of course, because this procedure involves an injection into the eye, its general use will be limited. However, it might open the door to less invasive ways of improving eyesight. As the authors explain:

"[I]n addition to visual ability enhancement, this nanodevice can serve as an integrated and light-controlled system in medicine, which could be useful in the repair of visual function as well as in drug delivery for ocular diseases."

These are early findings, so more work will be needed before scientists can use the technique widely; however, already, these results are intriguing and fascinating in their own right.

By Tim Newman, Medical News Today