Ben Feringa Nobel laureate explains how tiny chemical machines could change the world
Windows that clean themselves, cars that mend their own scratches, and precision antibiotics that only act in the exact site of an infection. Those are just some of the life-enriching inventions that could be made possible by “molecular machines”, according to Nobel prizewinning chemist Ben Feringa.
He says recent innovations in chemistry could pave the way to a greener and healthier future, enabled by tiny programmable devices, a millionth of a millimetre across, made from molecules engineered to move in response to stimuli, such as light, electricity or heat. “These molecular machines might have a dramatic effect on how we make materials and on what kind of smart functions we can do in the future,” says Feringa.
Feringa and two colleagues, Jean-Pierre Sauvage and Fraser Stoddart, received the 2016 Nobel Prize in Chemistry for the invention of molecular machines. He says their inspiration came from nature. “Your body is full of machines,” explains Feringa, noting that muscles can move thanks to natural molecular motors that literally “walk” along a filament. Similarly, tiny rotary motors—analogous to those found in cars, with proteins rotating inside a cellular bearing—allow bacteria to swim. Molecular machines imitate those biological processes with synthetic molecules.
Molecular machines for smart antibiotics
One example is smart antibiotics that help address antimicrobial resistance (AMR), where disease-causing bacteria evolve to withstand widely-used drugs. With conventional antibiotics, “the antibiotic goes everywhere in your body, and it also affects all the bacteria in your gut—the good bacteria,” says Feringa. Besides interfering with your digestive system, exposing bacteria to antibiotics unnecessarily increases the risk of them developing a resistance and causing incurable infections. “We want to have the antibiotic switched on exactly on the spot where the infection is,” he says. “We build in a tiny switch, like a light switch—a tiny molecular machine—and then with a flash of light we can switch the antibiotic on.” The problem of AMR won’t go away, but restricting antibiotics to the site of an infection will slow it down.
These tiny nanomachines could also be used to make new coatings for glass and paint, enabling windows and solar panels to clean themselves by shedding dirt and grease, and cars to repair their own scratches by knitting the molecules back together. Those examples are probably still a decade or so from the market, says Feringa. “My prediction is that 10 years from now you’ll have the first of these kinds of smart windows or self-cleaning windows in several places,” he says. “It might be 20 years until you can buy an expensive car which has a coating that repairs itself.”
Molecular machines are just one example of how chemical engineering can imitate nature, something Feringa says needs to happen on a broader scale to produce a greener, more circular economy. He points to the biological motors in the human body that produce its fuel. “They produce, per 24 hours, half your bodyweight in the molecular fuel, called ATP (adenosine triphosphate),” says Feringa. “Now you might enjoy a good meal, but you don’t eat half your bodyweight in fuel every day.” So where does all that fuel come from? Most of it is recycled from the body’s existing resources. “Nature knows how to recycle materials very effectively,” he says. “We have to learn from that, to translate how to do it in the chemical industry.”
Nanotechnology is already in the chemical industry. For example, catalysts—which spark or accelerate reactions between other chemicals—are often “designed with nano-scale precision,” Feringa notes. Greater precision in chemical processes could help to reduce energy use, such as by making it possible to create some reactions at lower temperatures.
Even as the burning of fossil fuels is phased out, oil will continue to have uses in petrochemistry—making plastics, for example. While that doesn’t have to be a problem in itself, petroleum-based plastics are difficult to recycle and often end up getting burnt, releasing carbon dioxide into the atmosphere. Chemists therefore need to come up with sustainable methods to break plastics down into recyclable components, find cleaner substitutes for petroleum–based building blocks in plastics, or both.
“A simple piece of plastic usually is not one component, it’s several components, and we have to separate them and make the pure starting materials, otherwise the chemical process does not work,” says Feringa. “It’s also important to come in with ‘step-in’ solutions from green materials: Instead of burning wood, use it to make a nice component to make plastic.” Feringa himself worked on a patented method for turning cellulose into polymers. However, “these are not separate worlds,” he cautions, “you cannot say suddenly ‘we will take wood and we will replace all these materials from the petrochemical industry.’”
Thanks to recent innovations, Feringa is optimistic about the prospect of a cleaner chemical industry. Feringa himself helped develop a new chemical process for manufacturing industrial detergents, the only by-product of which is water. Meanwhile, Shell recently demonstrated a method for turning carbon dioxide back into kerosine using wind-generated electricity. “Of course this is far away from a large scale application,” Feringa notes. “But they made 500 litres of kerosene and they had it mixed with the fuel of the plane,” which flew successfully.
As chemistry increasingly imitates nature, Feringa expects carbon dioxide to be recycled into other materials and fuels, as well as kerosine, noting “this is exactly what the green plant does.” Photosynthesising plants extract carbon dioxide from the air, and using sunlight as an energy source, they convert it into carbohydrates, such as starch and cellulose. That in turn provides the fruit and vegetables we eat and the wood we use for building. “If we can take CO2 from the air and we can have smart chemical processes in our industry to convert it into materials or fuel, we have a circular system,” Feringa explains. “This is the chemistry of the future.”
While it is a “long process” that will span generations, he argues sustainable chemistry is achievable if scientists join forces with industry to reduce waste, and employ greener inputs and more recycling. “This is exactly what we do in our advanced research centre, CBBC in the Netherlands,” he adds. Education is important too. “It’s a challenge for our young people,” Feringa notes. “We have to train our students and young people to go towards these opportunities, be daring and develop the methods and techniques and the skills to build the industry of the future—and that is what we are going to do.”
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