Chemical weapons are a dangerous and all-too-real threat. Now, a team of scientists has developed a new compound that can deactivate chemical weapons — including nerve agents like sarin — in just minutes.
A team from Northwestern University in Evanston, Illinois, have found inspiration for the new compound in enzymes called phosphotriesterases. Usually produced by bacteria, these proteins deactivate some pesticides — and nerves gases — in milliseconds. Problem is, those enzymes can break down easily, losing their ability to halt the actions of the dangerous compounds.
So the researchers attempted to reproduce the same effects using a synthetic catalyst. Science describes nicely how they went about the process:
They started with metal-organic frameworks (MOFs), a recently developed class of porous compounds composed of metals arranged in a crystalline network linked by carbon-based molecules. MOFs are highly adaptable materials... and because MOFs are porous, they have large surface areas that can rapidly create chemical bonds, making them good candidates for catalysts.
In the natural enzyme, phosphotriesterase, two zinc atoms act as so-called Lewis acids, which accept electrons to bind with the nerve agent. Once the agent has bonded, hydrolysis occurs — a water molecule attacks the agent, slicing and dicing essential chemical bonds, thereby deactivating it. The scientists designed a MOF with a similar structure, but they replaced the zinc with zirconium, which likewise behaves as a Lewis acid and makes for an ultrastable MOF.
In tests published in Nature Materials, the team used their catalyst to deactivate a pesticide similar to nerve agents but safer to use in the lab. Experiments showed that the new compounds — known as NU-1000 — deactivated half of the pesticide in 15 minutes. Further testing by US army facilities has shown that it neutralises half of the nerve agent GD — more toxic than the well-known sarin — in just three minutes. The researchers claim that that's 80 times faster than any previous compound has managed.
It's still not perfect, though. Indeed, the natural version — though fragile — works up to 100,000 times faster, so the team certainly has some way to go before it's as good as nature itself. But for now, it's a significant milestone in the quest to keep the world safe from chemical warfare. [Nature Materials via Science]
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