Nanoscale machines move liquid mountains

Controlled by light, transport the equivalent of world's tallest buildings

A molecular shuttle system

For the first time, nanoscale machines have moved macroscale objects—droplets of liquid that they can even transport up a slope. Researchers working on the project say that the feat is equivalent to a conventional mechanical machine using a millimeter displacement of pistons to lift an object twice the height of the world's tallest building.The scientists, from Edinburgh, Groningen and Bolognam, covered a gold surface with synthetic molecular "shuttles." Components of the shuttles move up and down by a millionth of a millimeter when exposed to ultraviolet light. This occurs because a chemical reaction takes place in one part of the molecule that causes it to repel another part. The changes in position alter the surface tension of a droplet of liquid placed on the gold surface.

In this way, the researchers have used their shuttles to shift microliter drops of diiodomethane both across a flat surface and up a one millimeter, 12-degree slope against the force of gravity.

While a tiny movement, it's considered a large leap forward for nanotechnology, as until now molecular machines largely haven't interacted with objects in the everyday world.

"Nature uses molecular machines in virtually every biological process and, when we learn how to build and control such structures, we will surely find they have the potential to revolutionize molecular-based technologies, from health care to 'smart' materials," says principal researcher David Leigh of the University of Edinburgh. "Molecular machines could be used to make artificial muscles, surfaces that change their properties in response to electricity or light or even—one day in the future—to move objects about a room using a laser pointer."

The research was announced at the BA Festival of Science in Dublin, and was reported in the journal Nature Materials.