Visual molecules change shape in nanotubes

Photos of changing shapes in the retina - an important element of vision - can help us understand how we look, a result recently published by researchers in Japan. .

Using illuminated electron microscopy, Kazu Suenaga and colleagues at the National Institute of Advanced Science and Technology (AIST) photographed a single retinal molecule. by attaching them to a carbon - 60 molecule in nanotubes. The team said that this work could lead to the creation of devices such as artificial eyes.

When the retinal molecules are stimulated by light, they change the shape of the bent word (cis) to straight (trans) . This shape triggers a class of biochemical reactions and eventually leads to an electrical impulse that will be sent along the optic nerve, thus allowing us to see.

To discover this mechanism, Suenaga and colleagues began by attaching a single retinal molecule to a fulleren carbon molecule so they could put this hybrid Ret - C60 into the nanotube. Single wall carbon. In this way the nanotubes act as a ' specimen holder '.

Diagram of molecules in the experiment. Cis retinal molecules
and trans are attached to C60 fullerenes in nanotubes. (Photo: VLVN)

Next, the researchers equipped an illuminated electron microscope with aberration correction to increase the spatial resolution without increasing the accelerating voltage of the microscope greater than 120 kV. With this average voltage and the fact that the sample lies in the carbon nanotubes, the biological molecules are not destroyed by the electron beam in the microscope.

The researchers achieved a 0.14 nm resolution, equal to the distance between two carbon molecules. This means they can see C-C bonds in the retina molecule when the shape changes from cis to trans.

"The dynamic nature of the retina molecule answers the sight," explains Suenaga. 'Our experiment thus allows us to discover how we see with the eye at the molecular level. It is said that the human eye is one of the most efficient receivers. If we can accurately change the retinal molecules at the single-molecule level, we can produce devices like artificial eyes, for example. '

Because the samples were not destroyed in a microscope, the development team said that the technique could be used to look at other molecules, not just for the retina molecule.'For example, to study phenomena that have been recognized at the molecular level such as protein bends or steric obstruction,' Suenaga said. The work is published in Nature Nanotechnology.