Scientists create biological shield to protect against chemical weapons – including sarin gas

Nanoparticle-wrapped enzyme can be administered before exposure to nerve gas and pesticides in mice.

Children receive treatment following a suspected toxic gas attack in Khan Sheikhun, a rebel-held town in the northwestern Syrian Idlib provinceMohamed al-Bakour/AFP

Scientists in the US and Russia have created a 'biological shield' that can protect against chemical weapons – including sarin, which is suspected to have been used in an attack in the Idlib province of northern Syria on Tuesday [4 April].

Sarin is an extremely potent nerve agent that is considered a weapon of mass destruction. It is estimated to be 26 times more deadly than cyanide and VX. Current reports indicate the latest attack in Syria had killed 58 people and injured many more.

Researchers from the University of North Carolina at Chapel Hill and Moscow State University have now announced a potent enzyme that can reverse and prevent poisoning by pesticides and nerve gas. While their trial was carried out on mice, the team hope it could one day offer protection and treatment to people exposed to these toxins.

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Publishing their findings in the Journal of Controlled Release, scientists were working on an enzyme called organophosphorus hydrolase. At present, animals and humans can be treated with this only after exposure. While early administration is effective at reversing symptoms. However, chemicals like VX and sarin gas work so quickly victims only have seconds to get the treatment.

The drug – atropine combined with pralidoxime – has been used to treat organophosphate-based toxins since WWII. However, they cannot be given to people in advance because of the major shock it causes in the body, the effect of which can be lethal.

Glass tubes to control the contamination of the chemical poison sarin is seen at the 'Bunker-Museum' in Rennsteighoehe, Germany.Reuters

Greene Shepherd, a specialist in clinical toxicology, who was not involved in the research, explained: "Two milligrams of atropine is a typical starting dose to counter organophosphate poisoning and it will make your heart to nearly jump out of your chest. A healthy person could probably survive it, but having something that could be administered in advance of exposure would be a very big deal."

In the study, researchers developed a way to wrap the enzyme into a nanoparticle. This could then be administered before, during and after exposure to organophosphate-based toxins. In mice, the team showed how their nanozyme circulated in the blood for 17 hours after one dose.

They believe this timeframe could be extended by making the nano wrapping even smaller, making it even better at hiding from the body's immune system (the enzyme is seen as a foreign invader so the body's natural response is to attack and clear it).

Any potential trial in humans is still a long way off. "Further evaluation of nano-OPH as a catalytic bioscavenger countermeasure against organophosphorus chemical warfare agents and pesticides is warranted," they wrote.

However, study leader Alexander Kabanov said the results are promising: "It could provide complete protection even if injected many hours before exposure to a lethal dose of toxin. The enzyme is so effective that just one molecule of the enzyme can decompose several thousand of molecules of toxin every second, so the nanozyme appears to be effective at much lower doses than other potential treatments."

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