“These three laureates . . . have opened this entire field of molecular machinery and shown us that you can make machine-like function at the molecular level,” said Olof Ramström, a member of Nobel chemistry committee.
He compared Sauvage, Stoddart and Feringa's breakthroughs to the invention of the first crude electric motors. Scientists in the early 19th century could not envision the countless ways that their spinning cranks and wheels would be put to use. But they had already “created a revolution,” he said.
Biology produces molecular machines all the time — they power our organs and allow our bodies to function. The motor protein kinesin is a model example: It literally walks along microtubules in the cell to transport cargo from one end to the other.
But since the 1950s, researchers have dreamed of manufacturing an apparatus that could function in the same way. The physicist and Nobel laureate Richard Feynman gave a seminal lecture on the subject in 1959, envisioning a “great future” in which “we can arrange the atoms the way we want; the very atoms, all the way down.”
Sauvage produced the first breakthrough in this effort in 1983, when he succeeded in producing two ring-shaped molecules linked by an easily manipulated mechanical bond. This was the first time chemists had manufactured a molecule that could be manipulated in this way. Later, Sauvage modified the structure so that one ring rotated around the other.
In 1991, Stoddart reinvented the wheel on a microscopic scale. He created a ring of molecules that moved along an axle in a controlled manner when heat was added. This shuttle zipped back and forth between two sites, powered only by the collisions of the molecules around it. The machine was eventually used to build a “molecular abacus” that could store information.
Feringa built on both of these breakthroughs to create the world's first molecular motor, a tiny spinning blade that rotates continually on an axis, in 1999. That molecule was developed into a “nanocar,” whose four wheels rotate to move the microscopic structure forward along a plane, like a minuscule car with four-wheel drive. Feringa also showed that the molecule could be used to rotate a glass rod thousands of times larger than the motor itself.
The researchers had to overcome two major challenges to produce their miniature machines, Nobel committee member Sara Snogerup Linse explained. First, they had to create molecules whose bonds were easily manipulated — links that worked more like a door hinge than a nail or glue.
“The other challenge is that molecular systems always want to reach equilibrium,” she said. “So it's a major challenge to create motion in one defined direction.”
Sauvage, 71, was born in France and is a professor emeritus at the University of Strasbourg as well as director of research emeritus at the National Center for Scientific Research in France. The Edinburgh-born Stoddart, 74, is a chemistry professor at Northwestern University, in Illinois. He has also been awarded a knighthood by Queen Elizabeth II for his scientific work. Feringa, 65, of the Netherlands, is a professor of organic chemistry at the University of Groningen.
The three laureates will share the prize of 8 million Swedish krona (almost 1 million U.S. dollars) equally.
“I feel a bit like the Wright Brothers,” Feringa said Wednesday in a phone call to the Royal Swedish Academy of Sciences, where the prize was announced. “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.”
The Dutch chemist said it's difficult to predict exactly where his innovations will lead. One application might be tiny medical robots that can travel through the bloodstream to search out a cancer cell or deliver medicine to a precise spot.
Asked whether he had any “nightmares” about the ways his work might be applied, Feringa demurred.
“I’m not so worried about it because once we are able to design these nanorobots, we will also have the opportunity to build in all kinds of safety devices if we need them,” he said.
Sauvage, Stoddart, Feringa and other researchers in their field have built about five dozen varieties of molecular machines in the past two decades. They include knots, switches, shuttles, rotors, pumps and chains, all at chemistry's smallest scale. The structures are still fragile and difficult to scale up; a car powered by a molecular engine is still a distant dream.
But the chemistry principles behind molecular machines are already being put to use. In 2015, researchers in Germany showed that you could take advantage of the weak mechanical bonds that operate molecular machines to create a version of the potent anti-cancer compound combretastatin A-4 that is turned on and off by light. This may allow doctors to target very specific areas of tissue and avoid destroying healthy cells.
Other labs have succeeded in using molecular machines to produce tiny peptide assembly lines and more-resilient plastics (including a film that can endure being beaten by a hammer).
“This field has come a long way,” Stoddart told Nature in 2015. “Now we have to start showing it's useful.”
This post has been updated.
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