20 October 2023

Nanomotor created from DNA: it makes pulsating movements

The miniaturized device works as a million-fold smaller version of an expander - a strength-training device for the hand. The development is described in the journal Nature Nanotechnology.

The researchers have developed a chemically driven nanomotor made of DNA molecules that is powered by a clever mechanism and makes pulsating movements - clenching and unclenching. Joined with other tiny components, the motor would be suitable for building nanorobots and nanomachines.

The motor is similar to an expander, a hand grip strength trainer in which two handles are connected by a spring into a V-shaped structure. To train, the grips are brought together by overcoming the resistance of the spring. If the grip is released, the spring returns the handles to their original position. "Our engine uses a similar principle. But the grips do not press against each other, but rather pull together," says Prof. Michael Famulok, co-author of the study from the University of Bonn.

The nanomotor is made up of long strands of DNA comprising almost 14,000 nucleotides. "Handles" are formed from 18 densely packed helices, between which an additional strand of DNA is stretched. Along it moves RNA polymerase attached to one of the "handles", which copies the stored information letter by letter.

The copying attracts the handles to each other. Near the end, a terminating nucleotide sequence is inserted into the DNA strand binding the handles, which signals the polymerase to let go of the DNA. When this happens, the "spring" relaxes and the handles separate. The process is then repeated.

The engine uses "nucleotide soup" as fuel. Each nucleotide has a small tail made up of three phosphate groups - triphosphate. To attach a new "letter" the polymerase removes two of these phosphate groups. This releases energy, which is used to join the nucleotides together.

In experiments, the researchers have shown that the motor can be combined with other nanostructures to create complex moving "cars." Scientists are working on a "clutch" that will allow the motor's power to be used only at the right moments, leaving the motor to idle the rest of the time.
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