Instant Colorimetric Discrimination and Degradation of GD/VX Nerve Agents Using Amidoxime–Isothiazolone–Polydiacetylene Composites

Abstract

Colorimetric sensors for organophosphorus nerve agent soften couple detection and degradation in a single inseparable process, limiting control over reaction rates and compromising selectivity.Here,we decouple these functions so that rapid neutralization precedes and enables VX-and GD-specific sensing. Highly nucleophilic 3-hydroxypyridyl amidoxime(HPAO) first accelerates the degradation of GD and VX agents. The resulting products-fluoride from GD and thiols fromVX-then trigger orthogonal optical responses. 2-Allyl-5-nitrobenzo[d]isothiazol-3(2H)-one (ITZ) undergoes ring-opening isomerization only with thiols, yielding a subsecondcolorless-to-yellow transition fluoride does not elicit this response. Inparallel, apolydiacetylene-oxime(PDA-Ox)matrixprovidesablue-to-red transition in the presence of organophosphates.Combining these channels yields red for GD and orange for VX, enabling rapid, intuitive visual discrimination,whiledecontaminationproceeds.Becauseneutralizationandsignalingarephysicallyandchemicallyseparated, the kineticsandreadoutcanbeoptimizedindependentlywhilemaintainingorthogonality.Wedemonstrateoperationinfour formats: (i)solution-phasedegradationwithconcurrentsensing,(ii)liquidmappingofcontamination,(iii)wearablepatch-baseddetection, and(iv)PDA-Ox−embeddedpatchesforGD/VXvisualdifferentiation.Thepatchesfurtherexhibitedenvironmentaldurabilityand chemical robustness under deployment-relevant evaluations-includingdiurnal temperature cycling, low-temperature exposure, high-humidity conditioning, photostability, and accelerated aging-as well as interference challenges, usingV-andG-series simulants,maintainingclear seriesdiscriminationuponsimulant exposurewithminimal backgroundcolor change.Wepresent a transformativetechnologythatfundamentallychallengesthetraditional“detect-then-decontaminate”paradigm,offeringpotential for militaryandcivilianchemicaldefensestrategies.