These DNA-sized nanobots are made for walking and sorting molecular cargo
The field of nanotechnology is still in its nascent stages, but recent innovations are increasingly making this science fiction world of tiny robots into a reality. New breakthrough research from a team at Caltech has demonstrated the ability of a robot made of a single strand of DNA to explore a molecular surface, pick up targeted molecules, and move them to another designated location.
"Just like electromechanical robots are sent off to faraway places, like Mars, we would like to send molecular robots to minuscule places where humans can't go, such as the bloodstream," says Lulu Qian, co-author on the paper. "Our goal was to design and build a molecular robot that could perform a sophisticated nanomechanical task: cargo sorting."
Previous work by a variety of researchers has successfully demonstrated the creation of such DNA robots, but this is the first time they have been shown to pick up and transport specific molecules.
To test the DNA robots, researchers designed what they called "molecular pegboards." These surfaces are 58-nanometers-by-58-nanometers, with each peg on the board made of a strand of DNA that is complimentary to the robot's "leg and foot." This allows the robot's leg and one of its feet to attach to a peg, while its other foot floats about freely driven by random molecular fluctuations. When the free foot comes into contact with another peg, the robot is pulled to it while the other foot is released. In this way, the robot is able to "walk" across the board following a random path.
Six fluorescent molecules were scattered over the board and it took a single DNA robot 24 hours to explore the entire surface. Additionally, when the robot encounters pegs that have moelcules tethered to them, it is able to pick up said molecule with its "hand" components and continue moving around until it happens across a designated drop-off peg. Although the process is slow, the researchers say it expends very little chemical energy and could be sped up adding more robots to the surface.
"Though we demonstrated a robot for this specific task, the same system design can be generalized to work with dozens of types of cargos at any arbitrary initial location on the surface," says former graduate student working on the project, Anupama Thubagere. "One could also have multiple robots performing diverse sorting tasks in parallel."
The researchers note that this study is still working through basic engineering principles and these DNA robots are currently not designed for specific applications, but this kind of early stage research is a key building block for the future of practical nanotechnology. The potential applications for this technology are far-reaching and Qian is excited over where the research could be heading.
Qian lists a variety of ways these robots could be used in the future, including "using a DNA robot for synthesizing a therapeutic chemical from its constituent parts in an artificial molecular factory, delivering a drug only when a specific signal is given in bloodstreams or cells, or sorting molecular components in trash for recycling."
The research was published in the journal Science.