DNA robot sorts molecules without external input


This "robot", composed of a single strand of DNA, can independently "walk" around a surface, pick up specific molecules and drop them off in selected locations.

In the study, the robots worked together to find and collect fluorescent molecules with individually achieving an 80 per cent chance of successful delivery.

Humanity sends Autonomous machines to explore the far reaches of space, but developing the DNA of robots it can learn to send them to inaccessible corners of the human body. Incidentally, the robots-each built from a DNA molecule of the single-strand variety which consisted of only 53 nucleotides- stood at an unfathomably small height of just 20 nanometers and each step covered a distance of only six nanometers. How rapidly each zipping and unzipping event happens and how much energy it consumes can be predicted for any specified DNA sequence, allowing researchers to regulate how fast the robot travels and how much energy it consumes to do a task. On a special surface was located 3 pink and 3 yellow molecules, the robot had to sort them by color, vary the desired area.

"It is also one of the first examples that we show we can have multiple DNA robots collectively performing the same task".

The nanobot, described in the journal Science, was constructed from three basic building blocks to provide "feet" for walking, an "arm" and "hand" for picking up objects, and a segment that can recognise a specific drop-off point and trigger the release of the cargo. For example, the A strand from one molecule can detach and attach with T from another and same goes for G and C. This property of DNA is essential for multiplication and evolution of genetic traits.

In prior experiments, DNA robots demonstrated their ability to perform simple tasks, but this latest effort ramped up the level of complexity considerably, while also opening a path towards the development of general-purpose DNA robots.

To see if a robot successfully picked up and dropped off the right cargo at the right location, the researchers used two fluorescent dyes to distinguish the molecules. Much more work needs to be done to figure this all out, and to test the DNA robots under different environmental conditions if we're ever going to have these things working in our bodies.

How do they pick up their "cargo"?

"We designed specific drop‐off locations for each type of cargo: If the type matches, the drop‐off location will signal the robot to release the cargo; otherwise the robot will continue to walk around and search for another drop‐off location", explained Qian. Then, they created a track made from DNA by putting one single sample on each peg of the track. However, at the moment, scientists were only able to design the DNA robot and its way of functioning.

Nanobionics researcher Wenlong Cheng from Monash University said the new research is exciting, because the team has designed a modular system with highly specific DNA robots.

"Another application is in the nanoscale device area".

"When you deliver them into the human body, it could potentially create risk if that genetic coding integrates into the genome information", he said. Qian and her colleagues say they could boost the speed by adding an enzyme to give extra thrust, or giving the robot a chemical motor.

The test robot was sent to roam around a 58 nanometre-wide molecular "pegboard" to which it was able to bind its "legs".

The creators compare your robot with assistants from science fiction.

Want more science from across the ABC?