"Nano-Train" Chemical Transport System Developed at Oxford University

Scientists at Oxford University and Warwick University have created a "nano-train" - a nanoscale transport network controlled by DNA.

The systems uses self-assembling tracks up to tens of microns long and "shuttles" made from kinesin, a motor protein. The researchers were able to use the system to concentrate a fluorescent green dye in the center of the network of tracks, causing a colour change.

Nanotrain network created by scientists at Oxford University: green dye-carrying shuttles after 'refuelling' with ATP travel towards the center of the network with their cargoes of green dye Image credit: Adam Wollman/Oxford University.

Systems like this could be used to move other chemical cargo around - for example, collecting dilute chemicals and bringing them together in one spot to allow chemical reactions to happen faster.

More complicated systems could also be made to behave like a construction site, using DNA and motor proteins to move components around a template for directed nanoassembly of much more complex structures.

The research, inspired by the way fish control the color of their skin, was published in Nature Nanotechnology. Fish cells contain melanophores, which in turn contain a network of radiating spokes.

Motor proteins carry pigment around this network -either concentrating it in the center, leaving much of the cell transparent, or spreading it out, giving the cell a more pronounced colouring.

The system developed by the Oxford researchers works in a very similar way. Assembler "nanobots", containing two kinesin motor proteins and a short strand of DNA for control, move around the network constructing the tracks.

The simpler carrier shuttle bots, containing just one kinesin protein, then carry their cargo around the network, using the chemical fuel ATP just like living cells. Adam Wollman from Oxford University's Department of Physics explained the benefit of using DNA strands for control:

"DNA is an excellent building block for constructing synthetic molecular systems, as we can program it to do whatever we need. We design the chemical structures of the DNA strands to control how they interact with each other. The shuttles can be used to either carry cargo or deliver signals to tell other shuttles what to do.

"We first use assemblers to arrange the track into 'spokes', triggered by the introduction of ATP. We then send in shuttles with fluorescent green cargo which spread out across the track, covering it evenly.

"When we add more ATP, the shuttles all cluster in the centre of the track where the spokes meet. Next, we send signal shuttles along the tracks to tell the cargo-carrying shuttles to release the fluorescent cargo into the environment, where it disperses. We can also send shuttles programmed with 'dismantle' signals to the central hub, telling the tracks to break up."



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