We’re talking about motors, elevators, even cars just a few nanometers long:
These machines could one day prove quite versatile, allowing scientists to develop artificial switches to release targeted drugs or develop new ways to store energy.
The prize will be split between Jean-Pierre Sauvage, Sir J. Fraser Stoddart, and Bernard L. Feringa "for develop[ing] molecules with controllable movements, which can perform a task when energy is added."
How to make a tiny molecular machine
The Nobel committee credited Sauvage, a professor at the University of Strasbourg, with the first big advance in 1983. Molecules typically join together through covalent bonds, with their atoms sharing electron pairs. But Sauvage’s team figured out how to link two molecules in a mechanical chain, using a copper ion:
Importantly, these molecules aren’t just fixed rigidly together. They're still able to move about. Once you take that step, you can start thinking about tiny machines.
Both Sauvage and Stoddart, of Northwestern University, began tinkering with this concept. In 1991, Stoddart’s research team built a molecular ring that fit around an electron-rich "axle." When he applied heat, the ring moved back and forth on the axle, like a shuttle:
This is called a rotaxane, and Stoddart later demonstrated that you could build extremely small computer chips with this structure.
Then in 1999, Ben Feringa, of the University of Groningen in the Netherlands, showed how to make mechanical motors out of molecules. Normally, molecules spin back and forth erratically. But Feringa created chemical structures that, when exposed to pulses of UV light, spun continuously in one direction:
A spinning motor allow chemist to build even more complex machines — like nanometer-scale cars, which Feringa first built in 2011.
Later in October, scientists around the world will hold the first nanocar race, speeding their creations down a gold atom surface:
So, uh, what can you do with molecular machines?
Everyone loves a good nanocar race, but the real value in molecular machines may lie elsewhere.
As Mark Peplow reports at Nature, some chemists have used the principle behind Feringa’s motor to develop light-activated switches that can deliver drugs in the body exactly where and when they’re needed, vastly increasing their effectiveness.
Other researchers have linked these motors together into long polymers that can heal themselves when scratched, which could lead to scratch-resistant films. Other materials could wind up or shrink when exposed to light — raising the possibility of developing new types of batteries, or adjustable sensors that react to light. Powerful nanomoters might one day help clean up pollution or repair small circuits.
It’s still early days, but chemists are convinced that molecular machines will eventually prove invaluable — doing things no other machines can do. The Nobel committee seems to agree: "Time has clearly shown the revolutionary effect of miniaturising computer technology, whereas we have only seen the initial stages of what could result from the miniaturisation of machines."
- The Nobel committee has a more detailed introduction to the research around molecular machines, and here’s an advanced look at the science.
- Earlier this year in Chemistry World, Victoria Richards looked at where research around molecular machines was heading. And Mark Peplow’s piece in Nature on scientists trying to develop applications is worth reading.