In the long human effort to understand and replicate the machinery of life, researchers at the University of Ulm have reached a quiet but significant threshold: a synthetic molecular motor that moves autonomously along a chemical track, powered by fuel alone, without any external command. Where biology has long employed proteins like kinesin and myosin to ferry cargo within cells, chemistry has now produced its own walker — humble in its components, profound in its implications. This achievement, years in the making, suggests that the boundary between the living and the constructed grows thinn
German Scientists Create First Autonomous Molecular Motor Powered by Chemical Fuel
The runner moves all on its own as long as it's supplied with fuel.
Mark
So they made a molecule move on its own. What's the actual breakthrough here—is it just that it moves, or is there something about how it moves?
Mimi
The how matters enormously. Before this, every artificial molecular motor needed external control—you had to keep adding chemicals or shining light on it. This one, once you give it fuel, just keeps going. It's autonomous.
Luke
But how long does it actually keep going? The paper says "for hours" when fuel is continuously added. That's not indefinite.
Mimi
Right, it's not perpetual. But it's the principle—the motor is self-sustaining as long as the fuel supply exists. That's what makes it different from the previous versions.
Mark
And the fuel is this molecule called carbodiimide? Is that something you'd actually use in a real application, or is it just a proof of concept?
Mimi
It's a proof of concept right now. The researchers are thinking about pharmaceutical synthesis—using these runners to move phosphate groups to positions that would otherwise be chemically unfavorable. That could unlock new drug compounds.
Luke
But they haven't actually done that yet. The paper demonstrates the principle in a controlled lab setting with glycerol and inositol tracks. Scaling that to pharmaceutical production is a different problem entirely.
Mark
What about the efficiency number—19 out of 100 fuel molecules result in a step. Is that good?
Mimi
For a first autonomous system, it's respectable. It shows the fuel isn't being wasted wildly. But whether it's good enough for industrial use, we don't know yet.
Luke
And the distance calculation—8.3 million kilometers per second—that's a theoretical aggregate, not a single molecule moving that fast. The reader needs to understand that's the collective output of 200 grams of runners all moving at once.
Mark
So what's the next step for them?
Mimi
They want to direct the runners in a single direction and have them transport cargo. Right now they're just stepping along the track. Making them move purposefully and carry things—that's the real engineering challenge ahead.
The Pulse
- For decades, artificial molecular motors required constant external prodding — light, electricity, or added chemicals — making true autonomy an elusive benchmark in nanotechnology.
- The Ulm team's phosphate 'runner' exploits a ring-shaped, spring-loaded molecular structure to snap forward one bond at a time, achieving multiple steps per hour without falling off its track.
- Experimental results were striking: fueled runners moved against their natural equilibrium, with 64 percent reaching a less stable but more advanced position on glycerol tracks, while unfueled controls drifted backward over weeks.
- For the first time, a single synthetic system combines processivity, autonomy, and kinetic asymmetry — three properties previously never united in one artificial molecular machine.
- The path forward points toward pharmaceutical synthesis and directional cargo transport, with the potential to chemically 'push uphill' reactions that nature and industry currently cannot easily perform.
In the long human effort to understand and replicate the machinery of life, researchers at the University of Ulm have reached a quiet but significant threshold: a synthetic molecular motor that moves autonomously along a chemical track, powered by fuel alone, without any external command. Where biology has long employed proteins like kinesin and myosin to ferry cargo within cells, chemistry has now produced its own walker — humble in its components, profound in its implications. This achievement, years in the making, suggests that the boundary between the living and the constructed grows thinner with each careful step.
Inside living cells, proteins like kinesin walk along filaments with quiet purpose, carrying cargo and powering muscle — all fueled by molecules the body produces naturally. Chemists have long tried to build artificial versions of these motors, and they have succeeded, but always with a catch: the machines only moved when pushed from outside, by light, electricity, or added chemicals. Max von Delius, a chemist at the University of Ulm who first made molecules run along tracks during his doctoral work in Edinburgh in 2010, has now crossed a harder threshold. His team built a molecular runner that moves on its own, as long as it is fed fuel.
The components are deliberately simple. The runner is a phosphate group — a molecule present in nearly every metabolic process in living things. The tracks are glycerol, with three attachment points, and inositol, a sugar with five. The central problem was making the phosphate actually step, since molecular bonds are extraordinarily stubborn under normal conditions, with half-lives measured in tens of thousands of years. The solution came from RNA chemistry: when the phosphate grabs two adjacent attachment points simultaneously, it forms a strained, ring-shaped structure — described by von Delius as a cocked crossbow — that snaps one bond within minutes. Add a fuel molecule called carbodiimide, and the cycle begins: the phosphate reaches forward, the ring forms and breaks, the rear foot releases, and the runner advances one step without ever losing contact with the track.
The results were clear. Without fuel, phosphate molecules drifted naturally to the outer, most stable edge of the glycerol track over several weeks. With fuel, the majority moved to a less stable middle position within two hours — moving against their natural tendency. On the longer inositol track, unfueled molecules showed no movement after eight weeks; fueled ones traversed all five positions, completing four full steps. The system proved efficient too, with nearly one in five fuel molecules consumed resulting in a successful step.
What makes this work significant is the combination it achieves: processivity, meaning the runner stays on its track; autonomy, meaning it moves without external direction; and kinetic asymmetry, meaning energy drives it away from equilibrium rather than toward it. No synthetic molecular machine had previously united all three. Von Delius and his team now envision using these runners to synthesize pharmaceuticals that are chemically difficult to produce, and eventually to carry molecular cargo in a single directed path. For now, the achievement stands as proof of concept: a machine made of molecules, powered by chemistry, moving without anyone holding the controls.
Inside cells, proteins move with purpose. Kinesin and myosin walk along filaments like tiny legs, ferrying cargo and contracting muscle fibers, all powered by a molecule the body makes naturally. For decades, chemists have tried to build artificial versions of these molecular motors. They succeeded—but only by pulling strings from the outside, adding chemicals or light or electric fields to make the machines go. Max von Delius, a chemist at the University of Ulm, had already made molecules "run" along a track back in 2010 when he was a doctoral student in Edinburgh. But that required constant external nudging. Now, in work he coordinated at Ulm, his team has crossed a threshold: they built a molecular runner that moves on its own, as long as you keep feeding it fuel.
The runner itself is simple—a phosphate group, the kind of thing that shows up in nearly every metabolic process in living things. The tracks are natural too: glycerol, a fatty substance with three spots where the phosphate can attach, and inositol, a sugar with five. The challenge was getting the phosphate to actually step. Bonds between molecules are stubborn. Under normal conditions, it would take roughly 140,000 years for half of them to break. A motor that's supposed to take several steps per hour cannot wait that long.
The researchers found their answer in a trick borrowed from RNA chemistry. When the phosphate group bonds with two adjacent hydroxyl groups at the same time, it forms a ring-shaped structure under tension—von Delius describes it like a cocked crossbow. Inside that strained ring, one of the two bonds snaps within minutes. Here's how a step unfolds: The phosphate group sits relaxed on the track with one attachment point. The researchers add fuel—a water-soluble molecule called carbodiimide, or EDC. The fuel activates the phosphate to grab a second foothold at the next position. The ring forms, tense and temporary. Water breaks one bond. The rear foot releases. The front foot holds. The phosphate moves forward one step without ever falling off the track. Add more fuel, the cycle repeats.
Patrick Alexander Hoffmann, the first author on the study, ran the numbers. Without fuel, 90 percent of the phosphate molecules drifted over weeks to the outer edge of the glycerol track—the spot where they naturally want to sit. With fuel, after about two hours, 64 percent had moved to the middle position, which is less stable but further along the path. On the longer inositol track, the difference was starker: without fuel, nothing moved even after eight weeks. With fuel, the phosphate stepped through all five positions, covering four complete steps. When fuel kept flowing, the motion continued for hours, steady and autonomous, like a real biological motor.
Von Delius calculated the efficiency. One mole of these runners—roughly 200 grams—collectively covers a net distance of about 8.3 million kilometers per second when moving. The fuel does this with remarkable economy: up to 19 out of every 100 fuel molecules consumed result in a successful step. The system now demonstrates three properties that had never been combined before in a synthetic molecular machine: processivity, meaning the runner stays attached to its track; autonomy, meaning it moves on its own once fueled; and kinetic asymmetry, meaning the energy input drives it away from where it would naturally rest. The work closes a gap that has existed in the field for years.
The practical applications are still ahead. Von Delius and his team envision using these runners to synthesize pharmaceuticals that are otherwise hard to make—moving a phosphate group to a position that would normally be unfavorable, essentially pushing it uphill through chemistry. Longer term, they want to direct the runners in a single, specific direction and have them carry molecular cargo. The research was funded by the European Research Council and the German Research Foundation. For now, the achievement is conceptual but concrete: a machine built from molecules, powered by chemistry, moving without a hand at the switch.
Notable Quotes
Our runner moves all on its own as long as it's supplied with fuel.— Max von Delius, University of Ulm
The fuel drives the system into a state it would hardly ever reach on its own—uphill, so to speak.— Patrick Alexander Hoffmann, first author
Want the full story?
Read the original at chemeurope.com ↗