Oct 8th 2025|7 min read
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KITAGAWA SUSUMU of Kyoto University, Richard Robson of the University of Melbourne and Omar Yaghi of the University of California, Berkeley will soon be enjoying a trip to Stockholm. They are this year’s winners of the Nobel chemistry prize, chosen for their work on metal-organic frameworks (MOFs). These, said Heiner Linke, who chairs the chemistry-prize committee, are like hotels for chemicals. Or perhaps self-assembling houses, added Olof Ramstrom, another committee member. Or Hermione Granger’s bottomless handbag in the “Harry Potter” books.
As their name suggests, MOFs are made of regularly spaced metallic clusters linked by long, thin organic molecules (in chemistry, “organic” means a molecule that contains at least one carbon and one hydrogen atom). It is the empty space in the resulting structure which makes them so interesting. Size the gaps right and a MOF can store large quantities of other, “guest” chemicals—hence Dr Linke’s hotel analogy. That makes them useful for everything from removing CO2 from industrial exhausts to extracting water from dry desert air.
Dr Robson helped pioneer the field. Inspired by the ball-and-stick models familiar to generations of chemistry students, he worked out how to make copper ions and a chemical called tetracyanotetraphenylmethane assemble themselves into a substance with the same pyramidal crystalline structure as diamonds, but with much bigger cavities in its crystal lattice. Not only a house for chemicals, in other words, but one that will happily build itself given the right conditions.
Dr Kitagawa was given his gong for helping persuade chemists of the promise of these then-new substances. As is often the case in science, Mother Nature had got there first. Chemists already knew about zeolites—minerals that likewise have structures with capacious gaps that can be used to capture other substances. Dr Kitagawa’s work helped convince the field that MOFs had big advantages over their naturally occurring rivals.
For one thing, zeolites are rigid solids. Dr Kitagawa demonstrated that MOFs could be made flexible if desired. And because MOFs are designed from scratch, their chemistry can be tweaked to make them adept at caging a particular target molecule. The near-infinite variety of organic chemistry means the linking molecules can be modified to do almost anything. Some MOFs have linkages that contain catalysts, meaning they can break down the substances they absorb into simpler components.
Dr Yaghi was honoured for his work in making those possibilities real. The committee flagged his creation in 1999 of MOF-5, described as the “paragon and showcase of the entire field”. The hollow structures of zeolites and MOFs mean that—like Ms Granger’s handbag—even small amounts can boast vast internal surface areas. A gram of zeolite might contain several hundred square metres of surface area within itself. MOF-5, by contrast, can manage nearly 3,000 square metres per gram. It is stable at temperatures up to 300°C and the size of its cavities can be tweaked to accommodate all sorts of molecular guests.
These days MOFs are a hot topic. Researchers have created versions that can pull oil spills out of water, store large quantities of hydrogen or methane, remove PFAs—a class of troublesome pollutants—from drinking water, cage drugs before releasing them at specific locations in the body, and even absorb and enzymatically break down antibiotics in the environment. A new and promising field of chemistry, in other words, even if it is one that is, as Dr Ramstrom quipped, “full of holes”.
The prize for physiology or medicine went to Mary Brunkow, Fred Ramsdell and Sakaguchi Shimon, for identifying regulatory T-cells (Tregs), the agents responsible for peripheral immune tolerance. This stops the immune system attacking cells in the body of which it is part. Such self-harm causes autoimmune conditions such as coeliac disease, multiple sclerosis and type-1 diabetes. Too much tolerance, however, can result in a failure to nip cancer in the bud—for one of the immune system’s jobs is to detect and destroy tumours before they get out of hand.
The trio’s journey started in the 1980s, after the paradoxical discovery that removing an organ called the thymus from mice led to an increase in immune activity. The paradox was that the thymus is the place where T-cells, a broad class of immune-system cell with various jobs to do, are made ready for action. Removing it might be expected to suppress immune activity, not boost it. Fascinated by this finding Dr Sakaguchi, who then worked at the Aichi Cancer Centre Research Institute in Nagoya, began searching for the thymus-based police force that was, presumably, keeping the system in check—and, in Tregs, he found it.
Illustration: Klawe Rzeczy/Getty Images/Unsplash
A few years later, in 2001, Dr Brunkow and Dr Ramsdell, who working at Celltech Chiroscience, a British biotech firm, investigated a strain of mice which develop a severe and lethal autoimmune disorder. They found the cause was a mutation in a gene called Foxp3—and that people with IPEX, a serious autoimmune condition, have similar mutations. Two years later, Dr Sakaguchi connected the dots and proved that Foxp3 governs the development of Tregs.
Peripheral immune tolerance is now an area of great interest in drug development. Being able to tweak that tolerance offers a rich seam of pharmaceutical potential.
Treating cancer needs less tolerance—in other words, fewer Tregs. One approach is to develop antibodies which flag Tregs for destruction by other cells of the immune system. Those with autoimmune conditions, however, need more tolerance. That might involve extracting Tregs, multiplying them and then re-introducing them into the body. The upshot of the work of Drs Brunkow, Ramsdell and Sakaguchi may thus be therapies for two quite different sorts of diseases: an excellent example of physiology leading to medicine in the way the prize’s double name alludes to.
Quantum computers, the topic that gave interest to the physics prize, are, some believe, the Next Big Thing. But the chips that would be needed to make them, though small on a human scale, are huge compared with the sub-atomic one that is the normal realm of quantum mechanics. It was for bridging this gap that John Clarke, John Martinis and Michel Devoret, working at the time at Berkeley, have received their award. They showed that a phenomenon called quantum tunnelling not only operates at a macro as well as a micro scale, but does so in a way that can be encoded into the quantum equivalent of the bits (electrical representations of the numbers one and zero) at the centre of conventional computing. Such “qubits”, in which ones and zeros are blended together rather than remaining separate, can be used to perform calculations intractable to conventional bits.
Quantum tunnelling is the ability of quantum objects (electrons, say) to appear on the far side of a barrier (often some sort of energy barrier) without actually leaping over it or physically passing through it. One type of radioactive decay, for example, depends on so-called alpha-particles (helium nuclei) tunnelling through the energy barrier that would otherwise keep them inside an atomic nucleus.
Cool things near to absolute zero, however, and such effects happen at a larger scale. At these temperatures, materials become superconducting, meaning electrons can pass through them without resistance. The electrons themselves can also merge into bigger structures called Bose-Einstein condensates which are able to quantum-tunnel across, say, gaps in a copper wire.
Such tunnellable gaps are called Josephson junctions. The contribution Drs Clarke, Martinis and Devoret made was to show, using a copper tube filled with powdered copper attached to a Josephson junction (an approach they call an artificial atom), that the current across the gap was, itself, quantised—ratcheting up and down stepwise, rather than continuously.
And there things rested until, in 1999, some researchers in Japan realised that if you could control the up and down ratcheting, you might use it to build a device that could process bits or, rather, since this would be a quantum device, qubits. That led to the invention of what are called phase qubits, which are oscillations between quantised energy levels in a Josephson junction. Those have led, in turn, to a more robust qubit design called a transmon, which Dr Devoret helped develop.
Whether quantum computers will live up to the hype remains to be seen. Cryptographers fear they will make currently uncrackable ciphers crackable. Biologists hope they will unveil the details of how protein molecules fold up into the shapes they need to assume to do their jobs. But perhaps the main lesson from the work of Dr Brunkow, Dr Ramsdell and Dr Sakaguchi is that the consequences of research are unpredictable, and that what appears abstruse may sometimes lead to unexpected, concrete outcomes. ■
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This article appeared in the Science & technology section of the print edition under the headline “Onwards and upwards!”
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