Nanomachines might be in their infancy as far as consumer goods, but they’re real enough to have attracted the attention of the Nobel committee. Jean-Pierre Sauvage, Fraser Stoddart, and Bernard Feringa have been awarded the 2016 Nobel Prize in Chemistry “for the design and synthesis of molecular machines.”
When Richard Feynman took the stage in his bare feet to talk about nanomachines at Caltech in 1984, he had in mind machines on the very smallest physical scale. Feynman wanted to make machines constructed of single atoms, and had some ideas about how that might take place. Things didn’t go exactly the way he envisioned, but his ideas have been made real with the gallery of nanomachines Sauvage, Stoddart, and Feringa have made.
The trio will share equally their 8M kronor (~$900K USD) prize. Their work is both pioneering and interconnected. It started with Jean-Pierre Sauvage’s work creating molecules that linked together like a chain. Normally, molecules are joined by strong covalent bonds in which the atoms share electrons, but in Sauvage’s chain they were instead linked in a whole different way: a mechanical bond. The result is called a catenane. Its parts can move relative to one another, which is a crucial defining characteristic for a machine.
If you were wondering what constitutes a machine, the wheel and axle is the only simple machine that fits this definition, and building on Sauvage’s catenane developments, Stoddart made a moving nano-wheel called a rotaxane in 1993. Feringa followed up with the first molecular motor in 1999, capable of rotating a glass cylinder ten thousand times its size. Since then, they’ve created a whole collection of working nanomachines, including a molecular elevator, an artificial muscle, a ring axle, and even a working four-wheel-drive molecular car.
One important finding that came out of all this research (PDF) is that chemically powered molecular machines, whether synthetic or biological, work the same way on a fundamental level: by selectively harvesting the kinetic energy of Brownian motion. That’s important, because it means there are no fundamental barriers in physics to operating systems at the ultra-tiny scale. (Those of you who are familiar with the way quantum mechanics gleefully throws away our cherished Newtonian assumptions are probably breathing a sigh of relief right about now).
Nanomachines have implications for drug delivery and microsurgery. With their moving parts, nanomachines could even disrupt and defeat biofilms, one of the most pernicious adversaries of internal medicine and transplants.
Modern medicine has achieved some incredible breakthroughs over the past 60 years, but our ability to precisely target infections, cancers, and other types of biological problems differs tremendously depending on what kind of problem it actually is. Even the tightest and most careful usage of radiation treatments for cancer almost always winds up blasting through healthy tissue on the way to the target area. Meanwhile, our primary methods for delivering antibiotics only deliver a tiny percentage of the actual dose you swallow 2-4x per day. The gap between the primitive nanomachines we can build today and the precise, sophisticated machines we would need to build to deliver some of what the technique could offer in the long-term is enormous. But just as the era of air travel began with a tiny hop at Kitty Hawk, the advent of nanomachines has begun with the creation of very simple devices without a clear use-case.
When asked about the practical applications of the nanomachines he and his colleagues developed, Feringa drew a frank comparison to the Wright Brothers. “People were saying, why do we need a flying machine? Now we have a Boeing 747 and an Airbus. That’s a little bit how I feel. The opportunities are great.” We may not know exactly how to apply these nanomachines right now, but continuing basic research will doubtless advance this frontier.
“Now let us talk about the possibility of making machines with movable parts, which are very tiny.” — Richard Feynman