Nanoparticles in the eyes allow mice infrared night vision

A nanoparticle-based technology that could perhaps one day allow humans an integrated night vision within their visual system has been developed by a group of researchers from the School of Medicine at the University of Massachusetts. Gang Han, the main author of the research, is in fact performing several experiments on mice by injecting into their eyes a special nanomaterial made from nanoparticle conversion (upconversion nanoparticles, UCNP).

These are organic particles that contain traces of rare earths, erbium and ytterbium that can convert the photons of infrared light into high-energy green light, i.e. light that mammals’ eyes can intercept.

The special nanoparticles have been attached to the photoreceptors of mice’s eyes with a protein bound in turn to a sugar molecule on the surface of the photoreceptors. After this first stage, they injected them behind the retinas.

They then started to test to see if the eyes could see infrared light. In the first phase, the mice were trained to swim towards a visible light that signaled the escape route. In a second phase, the visible light was replaced by infrared light.

Mice with special nanoparticles in their eyes could also see the escape route signal, unlike other mice that had not been injected.

After 10 weeks, the nanoparticles had not yet caused any obvious side effects, although Han himself admits that the level of biocompatibility is not yet completely clear at this stage and that further research will also have to be done to consider possible use in humans.