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Integrating DNA nanotechnology and RNA to transport nanoparticles along nanotubes

Credit: Purdue University image/Tae-Gon Cha

Another recent nanotechnology research advance in line with the theme of next month’s “Foresight Technical Conference: Integration“, integrating nanodevices and nanomaterials into more complex systems, is the combination of a DNA walker motor, RNA fuel, a carbon nanotube track, and a nanoparticle cargo, all mimicking the biological molecular machinery of protein motors using ATP fuel to walk along microtubule tracks (also made of protein) inside cells. A hat tip to ScienceDaily for reprinting this Purdue University press release written by Emil Venere “DNA motor ‘walks’ along nanotube, transports tiny particle:”

Researchers have created a new type of molecular motor made of DNA and demonstrated its potential by using it to transport a nanoparticle along the length of a carbon nanotube.

The design was inspired by natural biological motors that have evolved to perform specific tasks critical to the function of cells, said Jong Hyun Choi, a Purdue University assistant professor of mechanical engineering.

Whereas biological motors are made of protein, researchers are trying to create synthetic motors based on DNA, the genetic materials in cells that consist of a sequence of four chemical bases: adenine, guanine, cytosine and thymine. The walking mechanism of the synthetic motors is far slower than the mobility of natural motors. However, the natural motors cannot be controlled, and they don’t function outside their natural environment, whereas DNA-based motors are more stable and might be switched on and off, Choi said.

“We are in the very early stages of developing these kinds of synthetic molecular motors,” he said.

New findings were detailed in a research paper published this month in the journal Nature Nanotechnology [abstract].

In coming decades, such molecular motors might find uses in drug delivery, manufacturing and chemical processing.

The new motor has a core and two arms made of DNA, one above and one below the core. As it moves along a carbon-nanotube track it continuously harvests energy from strands of RNA, molecules vital to a variety of roles in living cells and viruses.

The Nature Nanotechnology paper was authored by graduate students Tae-Gon Cha, Jing Pan and Haorong Chen; former undergraduate student Janette Salgado; graduate student Xiang Li; Chengde Mao, a professor of chemistry; and Choi.

“Our motors extract chemical energy from RNA molecules decorated on the nanotubes and use that energy to fuel autonomous walking along the carbon nanotube track,” Choi said.

The core is made of an enzyme that cleaves off part of a strand of RNA. After cleavage, the upper DNA arm moves forward, binding with the next strand of RNA, and then the rest of the DNA follows. The process repeats until reaching the end of the nanotube track.

Researchers used the motor to move nanoparticles of cadmium disulfide along the length of a nanotube. The nanoparticle is about 4 nanometers in diameter.

The researchers combined two fluorescent imaging systems to document the motor’s movement, one in the visible spectrum and the other in the near-infrared range. The nanoparticle is fluorescent in visible light and the nanotubes are fluorescent in the near-infrared.

The motor took about 20 hours to reach the end of the nanotube, which was several microns long, but the process might be sped up by changing temperature and pH, a measure of acidity.

The 2007 Technology Roadmap for Productive Nanosystems pointed to the potential of combining nanotechnologies based on mimicking biological systems with a variety of synthetic nanoparticles and nanomaterials. The above work demonstrates a significant step along this path to molecular manufacturing. Perhaps the fact that this work was done in a mechanical engineering department is an indication that more engineers are looking toward rather esoteric provinces of the molecular sciences for potential advances in manufacturing technology, ultimately leading, we hope, to high throughput atomically precise manufacturing.
—James Lewis, PhD

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