Fast and accurate method developed for the detection of chemical warfare agents

Professor of Materials Science and Engineering and Director of the Illinois Materials Laboratory, Paul V. Braun, and Postdoctoral Fellow, Mohammad Amdad AliCREDIT: Department of Materials Science and Engineering of the University of Illinois

Researchers at the University of Illinois at Urbana-Champaign have developed a stamp-sized sensor capable of detecting traces of certain chemical warfare agents, such as sarin, within a few years. minutes. The research is published in ACS Omega.

Sarin is a neurotoxic agent made by humans that can spread as a gas or liquid. According to the Center for Disease Control, exposure to high doses will exceed stimulation of the glands and muscles and may result in loss of consciousness or respiratory failure. Even small doses can cause a long list of distressing and dangerous symptoms.

"Exposure to a low-level neurotoxic agent results in ambiguous signs and symptoms that can not be easily differentiated under other conditions, which may result in delayed treatment and permanent injury," said Paul Braun. Professor of Materials Science and Engineering and Director of the Materials Research Laboratory of Illinois. "If traces can be detected quickly, you can avoid permanent damage to human health."

"There are sophisticated sensors available, but they are bulky and expensive, so some people may be exposed to sarin without knowing it, and it's too late," he said. "Today's miniature sensors only showed the presence of a toxin, not the amount of exposure." Smaller existing sensors may also not be sensitive enough to provide adequate protection.

The technology implemented in this new article builds on previous work by the Braun group, which had developed "chemical black holes" on a small hydrogel surface, which attracted molecules to a point sensor via a gradient chemical potential.

The Braun group knew that the technology had potential but needed to be developed further.

"The problem was that the molecules were moving too slowly," said Braun. "It would take an hour to a day to move molecules a centimeter, and we did not have the best way to perform quantitative detection."

However, the technique of the chemical black hole proved that the science behind a chemical gradient would work, and the next step was to find a "detection technique that could have a real impact".

Knowing that they needed something smaller than slow-moving molecules, the researchers exposed to the DFPase enzyme a safe version of a molecule resembling sarin, which caused the hydrolysis of the molecule and its splitting into several parts. One of these parts was a negatively charged fluoride ion.

"The fluoride ion is easy to detect electrochemically," said Mohammad Amdad Ali, a postdoctoral researcher in Braun's group, and first author of the article. "And, because it's so small, it moves much faster than a molecule.If we have a surface with a positively charged gradient, focusing a point at the center of the sensor that really likes (attracts the Fluoride ion), instead of taking hours, it only takes a few minutes for all the fluoride ions to end up at one point. "

"We managed to create a gel film that not only decomposed the molecule, but also inserted the negatively charged fluoride ions into a sensor embedded in a fluoride-specific ion in the center, and read our amount of fluoride. we know the amount of fluoride we know how much sarin the sensor has been exposed to, "said Braun.

"The electrochemical sensor specific for fluoride ions has a low detection threshold and can therefore detect a very low level of fluoride ions," Ali said. "With the current state of our sensor prototype, we could detect a sarin-type molecule deposited by an aerosol from a vapor concentration as low as 0.01 mg / m3 in less than 10 minutes ", he added.

The next step is to test the sensors in an environment configured to handle the actual neurotoxic agent.

"The ultimate goal is to make something small enough, like a postage stamp, that can be worn on a uniform to detect gases or can be removed to test a surface that will tell in minutes if the product is going to work. agent is present and how much is there, "said Braun.

"It will not tell you about all the toxins, but very few compounds," he said. "If you discover that sarin is present, you have a much better chance of getting the appropriate antidote."

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