EU project aims at ultimate in miniaturisation: molecular machines

Making minute, molecular motors is the ultimate goal of the EU-funded SYNNANOMOTORS project, which was one of the winners of the Descartes Prize for Transnational Collaborative Research at the
recent European Science Awards.

‘Nature uses molecular motors and machines for every single biological process,’ said project coordinator Professor David Leigh of the University of Edinburgh in the UK. With these machines,
biological systems harness the sun’s energy, communicate, perceive the world around them and control our movements.

In contrast, mankind currently relies on machines based on ‘macro’ technologies. All our pharmaceuticals and materials are based on the static properties of these substances. Once you get down
to the nano-scale, molecules and atoms behave very differently, and this is what the researchers hope to exploit.

‘We’re used to machines in the big world,’ explained Professor Leigh. ‘What our work is about is trying to shrink this concept down to the ultimate in miniaturisation, where the machines are
molecules themselves.’

The inspiration for the project was a chance discovery. Professor Leigh and his team were trying to create a large, ring-shaped molecule as part of an attempt to create novel chemical sensors.
Instead, they produced two interlocked ring-shaped molecules which looked like a chain link.

Further research of this system led to the production of compounds called rotaxanes, in which a ‘wheel’ molecule fits round an ‘axle’ molecule. It was with these molecules that the
SYNNANOMOTORS team create the first molecular motor, when they used a surface modified with rotaxanes to transport a drop of liquid uphill. In this case, shining a light in front of the drop
caused the molecules to move in such a way that the water was effectively propelled along by the minute motors.

The project partners hope that this technology could one day be used to transport cargos, such as drugs, around the body. Meanwhile the nano-motors are also finding applications in information
storage. In a system with two interlocked rings, changing the orientation of the rings changes the properties of the substance. For example, in one orientation it might be fluorescent, in
another not. This means information can be ‘read’ optically from a polymer film covered in the molecules.

The first commercial applications of these miniscule motors are already in the pipeline, as project participant Professor Wybren Jan Buma of the University of Amsterdam in the Netherlands
explained.

‘If you put a very thin layer of these molecules on a surface, and then you touch them with a very sharp tip, of one atom across, and push on it, then you get patterns,’ he told CORDIS News.
The resulting pattern of droplets can be controlled, and a spin off company is now using this technique for identification and counterfeiting purposes. ‘So it is something that we are using
already,’ he added.

The project partners include European experts in chemistry, physics, surface science and nanotechnology. However, when accepting the award, Professor Leigh paid tribute to the hard work of the
younger members of the consortium. ‘I’m sure there’ll be lots of pizza and beer in the lab to celebrate!’ he said.

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