DNA nanotechnology has become one of the great hopes of molecular manufacturing in which large-scale objects could potentially be assembled from the most basic building blocks, atom-by-atom. Research is slowly revealing that many of the assumptions about DNA manufacturing are accurate, such as the ability of meeting design specifications down to atomically precise accuracy.
In the latest development for DNA manufacturing, researchers at Purdue University have developed a DNA motor that can transport nanoparticles up and down a carbon nanotube. While protein-based motors are doing this all the time in biological systems, the DNA the researchers have developed marks the first time that a synthetic molecule has been used to accomplish the same feat.
The DNA-based motor does not travel as fast as a protein-based motor does, but it does have the benefit of being controlled, of operating outside its natural environment and can be switched on or off.
The research, which was published in the journal Nature Nanotechnology (“A synthetic DNA motor that transports nanoparticles along carbon nanotubes”), demonstrated that DNA enzymes could transport cadmium sulfide nanocrystals along the length of a single-walled nanotube, deriving energy to carry its cargo by eating up RNA left along its path.
"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," said Jong Hyun Choi, a Purdue University assistant professor of mechanical engineering, in a press release.
The DNA enzyme has a core and two arms that come out from the top and bottom of the core. Movement of the DNA occurs as that core of the DNA enzyme cleaves a strand off the RNA. After one strand of RNA has been sliced off, the upper arm of the DNA enzyme grabs onto another strand of RNA and pulls the entire body along.
When the researchers concede that the DNA is slower at moving then their protein-based counterparts, they aren’t kidding. It took 20 hours for the DNA motor to move down the length of the carbon nanotube, which was several microns long.
While the researchers believe that increasing the temperature and acidity of the environment could speed up the process, it’s not clear how much they could speed it up.
It’s also not clear how RNA will always be around to help DNA motors to travel around in different environments. While molecular manufacturing adherents will no doubt be encouraged by this research, we may not need to worry about “grey goo” overrunning our planet as nanobots go about eating everything up to feed themselves.
Illustration: Tae-Gon Cha/Purdue University