Tiny DNA robots can sort and carry molecular cargo

Researchers from the California Institute of Technology (Caltech) have designed and synthesised robots from strands of DNA. 

The DNA robots were able to collect, transport and sort molecules, bringing the power of autonomous co-operation to the nanoscale – something normally reserved for much larger machines. 

The work, published in Science, demonstrates how a single strand of DNA can be designed to perform simple tasks. 

“It is one of the first steps toward developing the building blocks for general-purpose DNA robots,” said lead author Lulu Qian from Caltech. 

Alan Rowan, a materials chemist from the University of Queensland not involved with the research, called the study “an inspirational piece of science using the unique coding of life: nanometre-sized DNA polymers”.

The team fashioned their DNA robots from nucleotide modules that are combined to carry out a function. In this case, the robots consisted of a “leg” with two “feet” for walking, an “arm” and “hand” for picking up cargo, and a segment that could recognise a specific drop-off point and signal to the hand to release the molecule it was carrying. These functions are shown in a simple animation below. 

Conceptual animation of a single-stranded dna robot (blue) taking a single step on a linear track (gray).
Conceptual animation of a single-stranded DNA robot (blue) taking a single step on a linear track (gray).

The robots were designed to pick up two different fluorescent molecules – a yellow dye and a pink dye – then distribute them to two distinct regions on a small surface. The fluorescent molecules allowed the researchers to track the cargo as it were sorted by the robots.

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Each robot successfully sorted six scattered molecules, three pink and three yellow, into their correct places within 24 hours. 

If this isn’t fast enough for you, simply adding more DNA robots to the surface reduced the time it took to sort the molecules. 

Although each robot could only carry one molecule at a time, in the future the scientists believe DNA robots with multiple “hands” could be used to carry different molecules simultaneously and work together in nanoscale factories to build therapeutic molecules.

“We’d like to develop more building blocks for DNA robots to perform more diverse functions,” said Qian. “We are also interested in adding simple communication between robots, so they can cooperatively perform more complex tasks, like a swarm.”

However, it could be a while before these robots play a significant role in our daily lives.

“This is a first small step towards parallel processing at the nanoscale,” said Rowan. “How to integrate these devices into genuine modern-day applications remains a challenge which will take decades.”

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