Engine design and experimental assembly. a,b, Sketches of a pedestal and a triangular platform, respectively. Cylinders indicate DNA double helices. c, Schematic illustration of the motor mounting steps. d,e, Rotor arm components. f, Left, schematic illustration of the experimental setup for observing motor dynamics in an inverted TIRF microscope. The pedestal is attached via various biotin-neutravidin linkages to a microscope coverslip. Orange star, Cy5 tints. Blue stars, labeling positions for DNA-PAINT imager strands. On the right, two platinum electrodes are immersed in the liquid chamber from above and connected to a function generator that generates a square-wave alternating current to create a fixed-axis energy modulation that acts on all the motors. Credit: Nature (2022). DOI: 10.1038/s41586-022-04910-y
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A research team led by the Technical University of Munich (TUM) succeeded for the first time in producing a molecular electric motor using the DNA origami method. The tiny machine made of genetic material self-assembles and converts electrical energy into kinetic energy. The new nanomotors can be turned on and off, and the researchers can control the speed of rotation and the direction of rotation.
Whether in our cars, drills, or automatic coffee grinders, motors help us get things done in our everyday lives to accomplish a wide variety of tasks. On a much smaller scale, natural molecular motors perform vital tasks in our bodies. For example, a engine A protein known as ATP synthase produces the molecule adenosine triphosphate (ATP), which our bodies use for short-term storage and energy transfer.
While natural molecular motors are essential, it has been quite difficult to recreate motors on this scale with mechanical properties roughly similar to those of natural molecular motors such as ATP synthase. Now, a research team has built a nanoscale molecular rotary motor that works using the DNA origami method and published their results in Nature. The team was led by Hendrik Dietz, Professor of Biomolecular Nanotechnology at TUM, Friedrich Simmel, Professor of Physics of Synthetic Biological Systems at TUM, and Ramin Golestanian, Director of the Max Planck Institute for Dynamics and Self-Organization.
A self-assembled nanomotor
The new molecular motor consists of DNA:genetic material. The researchers used the DNA origami method to assemble the motor from DNA molecules. This method was invented by Paul Rothemund in 2006 and later developed by the TUM research team. Several long DNA strands serve as a base to which additional DNA strands are attached as counterparts. DNA sequences are selected such that the attached strands and folds create the desired structures.
“We have been advancing this manufacturing method for many years and now we can develop very precise and complex objects, such as molecular switches or hollow bodies that can trap viruses. If you put the DNA strands with the correct sequences in solution, the objects will self-assemble.” Dietz says.
The new nanomotor made of DNA material consists of three components: base, platform and rotor arm. The base is about 40 nanometers tall and is attached to a glass plate in solution via chemical links on a glass plate. A rotor arm up to 500 nanometers long is mounted on the base so it can rotate. Another component is crucial for the engine to work as intended: a platform that sits between the base and the rotor arm. This platform contains obstacles that influence the movement of the rotor arm. In order to pass obstacles and turn, the rotor arm needs to be bent up a bit, like a ratchet.
Structural analysis of the DNA origami engine. a, Different views of a 3D electron density map of the engine block determined by single-particle cryo-EM (see also Extended Data Fig. 4 and in the Electron Microscopy Data Bank (EMDB) under code EMD-14358). b, detail of the cryo-EM map of the engine block represented in different density thresholds in which the three obstacles and the rotor spring can be distinguished. Inset, schematic showing the six preferred residence sites of the rotor arm. c, Exemplary negative-staining TEM images of a motor variant with an attached long rotor arm. Scale bar, 50 nm. d, Exemplary single-particle fluorescence images. Scale bar, 500 nm. The images show the standard deviation of the average intensity per pixel calculated over all frames of the recorded TIRF videos. e, DNA-PAINT images showing the positions of the tip of the rotor arm relative to the triangle platform. Scale bar, 500 nm. Credit: Nature (2022). DOI: 10.1038/s41586-022-04910-y
Nature (2022). DOI: 10.1038/s41586-022-04910-y”/>
Directed motion via AC voltage
With no power supply, the motors’ rotor arms move randomly in one direction or another, driven by random collisions with molecules in the surrounding solvent. However, as soon as AC voltage is applied across two electrodes, the rotor arms directionally and continuously rotate in one direction.
“The new motor has unprecedented mechanical capabilities: it can reach torques in the range of 10 piconewtons per nanometer. And it can generate more energy per second than is released when two ATP molecules are split,” explains Ramin Golestanian, who led the theoretical analysis. of the engine mechanism.
The directed motion of the motors results from a superposition of the fluctuating electrical forces with the forces experienced by the motor. rotor arm due to pawl obstacles. The underlying mechanism performs a so-called “intermittent Brownian ratchet”. The researchers can control the speed and direction of the rotation through the direction of the electric field and also through the frequency and amplitude of the AC voltage.
“The new engine could also have technical applications in the future. If we further develop the engine, we could possibly use it in the future to power user-defined engines.” chemical reactions, inspired by how ATP synthase produces ATP driven by rotation. So, for example, the surfaces could be densely coated with such engines. I would then add starting materials, apply a bit of AC voltage, and the motors would produce the desired chemical compound,” says Dietz.
Anna-Katharina Pumm et al, A DNA Origami Rotary Ratchet Engine, Nature (2022). DOI: 10.1038/s41586-022-04910-y
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Citation: First electric nanomotor made of DNA material (July 21, 2022) Retrieved July 25, 2022 at https://phys.org/news/2022-07-electric-nanomotor-dna-material.html
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