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

Colorimetric sensors for organophosphorus nerve agents often 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 from VX─then trigger orthogonal optical responses. 2-Allyl-5-nitrobenzo[d]isothiazol-3(2H)-one (ITZ) undergoes ring-opening isomerization only with thiols, yielding a subsecond colorless-to-yellow transition; fluoride does not elicit this response. In parallel, a polydiacetylene-oxime (PDA-Ox) matrix provides a blue-to-red transition in the presence of organophosphates. Combining these channels yields red for GD and orange for VX, enabling rapid, intuitive visual discrimination, while decontamination proceeds. Because neutralization and signaling are physically and chemically separated, the kinetics and readout can be optimized independently while maintaining orthogonality. We demonstrate operation in four formats: (i) solution-phase degradation with concurrent sensing, (ii) liquid mapping of contamination, (iii) wearable patch-based detection, and (iv) PDA-Ox-embedded patches for GD/VX visual differentiation. The patches further exhibited environmental durability and chemical robustness under deployment-relevant evaluations─including diurnal temperature cycling, low-temperature exposure, high-humidity conditioning, photostability, and accelerated aging─as well as interference challenges, using V- and G-series simulants, maintaining clear series discrimination upon simulant exposure with minimal background color change. We present a transformative technology that fundamentally challenges the traditional "detect-then-decontaminate" paradigm, offering potential for military and civilian chemical defense strategies.