Micro-subs may soon tour body to kill bugs

THE PROSPECT of miniature robots being let loose inside the body to perform minor surgery has come a step closer with the invention of prototype "molecular motors".

Microscopic engines, powered by chemical fuel or light, could be used to drive the propellers of tiny submarines for repairing internal organs or unclogging blocked blood vessels, in a way reminiscent of the 1966 film Fantastic Voyage.

Two teams of scientists have independently devised motors from complex molecules, which can be manipulated to move or rotate in a watery solution.

Although scientists have observed rotating molecules that move in both directions, research published in the journal Nature demonstrates how the phenomenon can be adapted to make the molecule turn in one direction by expending energy.

One engine, built by Ross Kelly and colleagues at Boston College in Massachusetts, uses chemical fuel to rotate a carbon-based molecule through an angle of 120 degrees. The other, devised by Ben Feringa of the University of Groningen in the Netherlands, shows how light energy can rotate a molecular motor through 360 degrees.

Anthony Davis, professor of organic chemistry at Trinity College, Dublin, says that both inventions provide important evidence that it is possible to build small-scale engines to manipulate or move molecular-sized tools or instruments. "One is a bit like an internal combustion engine where you put in petrol to turn the engine in one direction. The other uses light as a source of fuel," Professor Davis said.

One future application for the light-sensitive device could be to place it on the side of a microscopic particle or instrument that can be moved around using the rotating molecule as a propeller.

"People have imagined micro-robots that would go through your blood vessels to strip them of cholesterol deposits. This molecular engine could be the propeller for such a device," Professor Davis said.

Engineering on a miniature scale has been the dream of scientists since the late Fifties.While physicists and engineers have been producing smaller and smaller devices, working from the top down, chemists are working from the bottom up by synthesising bigger and bigger molecules to perform ever-more complex functions.