DNA robots

The Dinky Amigos spend much of their time in a double line (or double strand) paired with their best friends. The line is not straight. Rather it wiggles into a shape that looks something like a spiral staircase. This is known as a double helix. Sometimes, however this double strand has to split and become two single strands. For example during replication,  which occurs when a cell grows or gets damaged and both strands are copied to make two new double stranded helices.

When in a double strand,  the Dinky Amigos pair up with their best friends. Gina and Crispin like each other the most. If there are lots of Gina and Crispin’s cousins in a single strand, then this strand may not stay single for very long.


There will be a loop in the line known as a hairpin. A spontaneous hairpin is rather inconvenient in the cell, which has mechanisms to try and prevent this. This is also extremely inconvenient to the lab researcher. They too have mechanisms to try and prevent them. (Hairpin loops are not entirely unwanted, and spend much of their useful life in the cell telling others when to stop.)

But happily for the hairpin (and indeed Gina and Crispin), it has become the latest darling for engineers at John Hopkins University in the US for a potentially new function – robotics.

Hydrogel squares have been embedded with specific DNA sequences. These Dinky Amigo line-ups can encourage their friends in the hairpin loop to join them. Once attracted by the sequence, the loop straightens out – thus increasing the size of the gel. This straightened sequence then encourages the Dinky Amigos in other hairpins to join in. Lots of hairpins can join together, making the hydrogel stretch further. In this way, researchers have managed to increase the size of a 1cm x 1cm square to 100 times its size.


By creating different sequences on the gel and adding in greater or lesser concentrations of the hairpin, the hydrogel sample can be encouraged to bend or fold. The creation of a Terminator Hairpin means that researchers can also stop the process. This terminator has a loop like the other hairpins, but no sequence which will attract others.

This technology is breaking new ground for the area of soft robotics and could eliminate the need for batteries or wires. Similarly, it may be opening a door in the field of smart medicine, where artificially intelligent tools are designed to assist with a medical diagnosis. Research is still at an early stage, but patents are pending and hope is high that the humble hairpin may transform technology and create DNA robots.