Pharmaceutical drugs have an environmental cost in addition to a financial one. The average pharma plant uses nearly 15 times as much energy per square foot as a commercial office building, some of which is used for the chemical reactions required to make common medicines such as anti-malarial drugs.
Now, researchers in the Netherlands say they’ve found a way to cut these energy costs by using sunlight and an artificial leaf to manufacture drugs whenever and wherever, from the jungle to the craters of Mars.
Their work, published last month in Angewandte Chemie, a journal of the German Chemical Society, demonstrated the production of medically relevant chemicals (including an intermediate form of the anti-malarial drug artemisinin) using modified solar concentrators, which capture light much like leaves do.
A team led by Timothy Noël, an associate professor at the Eindhoven University of Technology in the Netherlands, combined these solar concentrators—which, adorably, can be made to look like actual leaves—with tiny pathways called microchannels. Ingredients sit in these channels, which look a bit like the veins on a leaf, and are spurred to react by energy from sunlight. To produce ascaridole, an anti-worm drug, the researchers used a lamp equipped with a bulb that simulated typical solar conditions, but they used natural light to make the anti-malarial precursor.
“Solar energy is abundantly available but is too diffuse to be really useful to carry out chemistry,” Noël said in an email. “We have overcome this issue by making a reactor which can harvest solar energy and focus that energy to reaction channels.”
Noël and his team created a prototype version of this technology in 2016, which consisted of a silicone grid dyed red. In the years since, they switched the grid to be made of plexiglass and dyed it red, green, and blue. The leaf-shaped versions highlight the similarities between the microchannels and naturally occurring veins in leaves, but Noël said the reactors used in their experiments tend to be squares for ease of calculation. Still, the leaf-shaped design works the same as the square, he said.
In 2018, Noël’s team added a feedback system to the prototype that keeps light production from the solar concentrator constant during changes in weather and cloud cover. Noël said that the latest version has a lifetime of around 20 years and can be produced at less than $55 USD per square meter. Mass production may further lower these costs, he added.
In addition to cutting costs, the solar reactors sped up the chemical reactions tested. In one case, reaction time dipped from six hours to five minutes. Noël said this is due to the use of the microchannels, which he contrasted with the way light permeates the ocean: As you wade deeper into the sea and look down, you’ll stop seeing your feet, as light only reaches the top layers of the water. Similarly, in a large reaction chamber exposed to light, the energy will only reach the exterior and not permeate to the middle. Microchannels maximize the amount of reagent exposed to light and accelerate the reaction, he said.
The team's nature-inspired approach could allow for the production of medicine outside a pharmaceutical lab, even locally to where specific drugs are needed.
“Using a reactor like this means you can make drugs anywhere, in principle, whether malaria drugs in the jungle or paracetamol on Mars,” Noël said in a 2016 statement. “All you need is sunlight and this mini-factory.”