The unsung mighty molecules Written by Alan Barker, Freelance Writer, British Science Festival Why should we care about supramolecules? They were the subject of the 2016 Nobel Prize in Chemistry but they’re still largely underappreciated. Imogen Riddell wants to change that. She’s delivering this year’s Rosalind Franklin Award Lecture for Physical Sciences and Mathematics at the British Science Festival. Imogen talked to Alan Barker. Your talk is called “The unsung mighty molecules”. What are these molecules and why are they unsung? Well, they’re actually supramolecules. A molecule, is a group of atoms held together by a physical bond, a sharing of electrons. Supramolecules are interactions between molecules that are bonded in some other way – not by sharing electrons. And they’re unsung because they’re new, and we’re only just beginning to learn about them. Can you give us an example of a supramolecule? If you look at DNA, you see two strands of molecules held together similar to a pair of railroad tracks – by a hydrogen bond. That’s not a classical bond. I’m interested in supramolecules that have a different shape: they’re container molecules. Imagine a molecule that’s like a box, with another molecule inside. There’s nothing physically holding them together, so the molecule inside retains its shape and function. A bit like a cool box that can package ice, allowing you to take the ice into the desert and for it to remain frozen What can you use these molecules used for? It’s a very young field, and many potential applications are only just being realised. But I guess one of the big drivers is for medicinal applications. If you can package a drug molecule in a container molecule, for example, you could take it orally so that it would survive the acidic environment of the stomach – enabling it to pass intact into the bloodstream. The other application that most people don’t know about is Febreze. It contains tyre-shaped molecules of different sizes that can capture different odour molecules; when you spray it, some of it is trapping the odour molecules preventing the sensors in your nose detecting the odour. What’s the worst potential application? Military, maybe? Well, when I did my PhD, the group I joined had recently published a paper about encapsulating P4 – white phosphorus, which had recently been used in the Middle East – and we promoted that as a way to mitigate, remediate and contain a spill. I’m not sure that anyone is using it to package some kind of weapon... But you could engineer a molecule to go around and mop up harmful chemicals in the air? That’s a large part of what we do. We have to make the right shape and size to pick up the molecule that we’re after – it’s like a jigsaw. We have container molecules that could capture SF6, which is the arguably the most potent greenhouse gas. It has very high industrial importance and we have nothing to replace it, but we have containers to capture, recycle and reuse it. A lot of research groups are trying to engineer container molecules for CO2... What are you doing in your own research? I’m interested in biomolecules – proteins in particular. Proteins are large structures that will only work when folded in a very specific orientation. If you put them into an unusual environment they might lose that shape and lose their function. If you could package the folded protein, you might be able to put it into a hostile environment and it could start to perform its function there. The biotechnology industry is very interested in this idea. Chemical companies are interested in using proteins – specifically enzymes – to carry out chemical transformations. You might want to create a polymer, for instance, which joins lots of small molecules together. Normally this is done in a solvent in which proteins couldn’t survive; if you could help them to survive in that solvent, you might be able to do things in a more environmentally friendly way. The Unsung Mighty Molecules is at 12.30 on Wednesday 6 September. Book tickets on the British Science Festival website.