Organophosphate pesticides and chemical warfare agents (CWAs) irreversibly phosphorylate and therefore inhibit acetylcholinesterase (AChE), a serine protease that hydrolyzes the neurotransmitter acetylcholine, causing neuromuscular paralysis. In order to effectively sense OP compounds and CWA threats in general, we are developing a system based on a hydrogel swelling/deswelling in response to OP compounds that provides simultaneous detection and actuation capability, allowing automated smart response of a material to an OP threat. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/39731_figure_1.jpg' alt='' />To effectively detect all organophosphate agents that inhibit AChE activity, a polymieric hydrogel is designed that contains weak, reversible AChE inhibitors as pendant groups of a water-soluble polymeric backbone. The presence of the tetrameric enzyme, AChE, leads the pendant inhibitors to bind and occupy most of the active sites of the enzyme, physically crosslinking the polymer to form a highly crosslinked gel. When exposed to OP compounds, the reversible inhibitor is displaced by the strong, irreversible binding of the OP, leading to a reduction in the density of physical crosslinks and consequently swelling of the gel that can actuate chemical sensing into a mechanical response. Our system's flexibility to respond to a wide variety of OP threats (stronger OP ligands), its ability to incorporate multiple inhibitors, the utilization of water as a solvent, as well as the ability to irreversibly absorb OPs and the capability to enhance the sensing signal, make our hydrogel swelling system a strong candidate for OP sensing and response.

Sensing organophosphate compounds through a polymer-protein physical network disruption

247th National Meeting (2014)

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