The molecular motor does not need anyone to operate

A windmill-inspired molecular motor can run on its own, powered by a fluid flow. A research group in Delft has built a motor that is 450 nanometers long and 8 nanometers thick — 10,000 times thinner than a hair. It is the first molecular motor moved by a fluid flow. Researchers Posted Thursday About their molecular machine in Nature Physics.

The motor that the folks at Delft designed have the shape of windmill blades. When a fast stream of fluid moves against it, it pushes against the blades and begins to rotate. Previously, the molecular motor could only be manually operated using pulses of light or electricity. But the new engine does not need anyone: under the right conditions, it rotates on its own, at a rate of ten revolutions per second.

The researchers made a 50-nanometer hole in a thin film. Fluid flow is initiated by placing a “salt gradient” across the membrane. If the interior of the membrane is more salty than the outside, the water flow will move inward until the salt distribution is equalized again. This is simply due to the laws of nature – or more precisely, thermodynamics. The motor exactly fills the hole in the membrane. The salt gradient causes the fluid to move, the blades to rotate and the molecular machine to operate.

approx double scoop

It didn’t matter too much, or the people of Delft had a double scoop. Not only is this the first motor to work on fluid flows, the motor is also made of DNA origami. This is a technique in which chemists can glue pieces of DNA together with pinpoint accuracy to form microstructures. It is the second molecular engine ever made from DNA: just a few weeks ago, a German research group published in temper nature about the first. „Our paper has been sent to temper nature Submit,” says Ces Decker, a professor of molecular biophysics at TU Delft and the study supervisor. “We had hoped to publish together, but it did not go as planned. Ah, that’s how it goes sometimes.”

The field of molecular machinery stands out due to the high expectations, while research remains almost entirely basic. These predictions were confirmed in 2016 by the Nobel Prize, which was awarded to Dutch chemist Ben Feringa, among others. The winners built one of the first working machines: motors that start spinning when a light is shining on them or when an electric current is flowing. Feringa even built a molecular car with spinning wheels.

At the moment, it is not clear what the added value of moving molecules is, but chemists would like to make a comparison with the industrial revolution. When people started building machines on a large scale, the world changed. They expect that such an industrial revolution is imminent in chemistry.

of great value

In addition, there is already tangible evidence that molecular machines can be of great value, Decker says. “In our bodies there are biochemical actuators at the nano-scale, in a way that proves that they work. It all happens at this nanoscale in biology: the interaction between molecules. But developing a nano-engine is still a bit like inventing the wheel. It’s an obvious building block, but It is not immediately clear which devices will become very important in the future.”

“This work is another milestone in the very successful history of nanotechnology,” Andreas Hermann says. He is Professor of Materials and Molecular Systems at the Aachen University of Technology. “This is the first example of an artificial rotary machine inside a thin membrane. In nature, these rotating molecular machines are very important, for example, for the movement of bacteria or the production of fuel in a cell. It is a great achievement to make your own comparable machine.”

“Right now, machines are still little gears that convert energy into mechanical motion,” he continues. “If the team continues to work together with great success, they can link it to the chemical production of valuable molecules, just like what happens in nature when making fuels in cells. Perhaps it is possible to bring about such interactions with the separation of fresh water and sea water by a membrane.”