posted on 2024-02-08, 13:12authored byTyler Marlar, John N. Harb
Among nerve agents, V-series nerve
agents are some of
the most
toxic, making low-concentration detection critical for the protection
of individuals, populations, and strategic resources. Electrochemical
sensors are ideally suited for the real-time and in-field sensing
of these agents. While V-series nerve agents are inherently nonelectroactive,
they can be hydrolyzed to electroactive products compatible with electrochemical
sensing. Zr(IV) MOFs are next-generation nanoporous materials that
have been shown to rapidly catalyze the hydrolysis of nerve agents.
This work makes use of these nanomaterials to develop, for the first
time, an MOF-enabled electrochemical sensor for V-series nerve agents.
Our work demonstrates that the VX thiol hydrolysis product can be
electrochemically detected at low concentrations using commercially
available gold electrodes. We demonstrate that low-concentration thiol
oxidation is an irreversible reaction that is dependent on both mass
transport and adsorption. Demeton-S-methylsulfon, a VX simulant, is
used to demonstrate the full range of sensor operation that includes
hydrolysis and electrochemical detection. We demonstrate that MOF-808
rapidly, selectively, and completely hydrolyzes demeton-S-methylsulfon
to less-hazardous dimethyl phosphate and 2-ethylsulfonylethanethiol.
Low-concentration measurements of 2-ethylsulfonylethanethiol are performed
by using electrochemical techniques. This sensor has a limit of detection
of 30 nM or 7.87 μg/L for 2-ethylsulfonylethanethiol, which
is near the nerve agent exposure limit for water samples established
by the United States military. Our work demonstrates the feasibility
of rapid, robust electrochemical sensing of V-series nerve agents
at low concentrations for in-field applications.