Discriminative detection of various organophosphorus nerve agents and analogues based on self-trapping probe coupled with SERS

Organophosphorus nerve agents (OPNAs) are highly lethal chemical warfare agents (CWAs), which poses a serious threat to human health and safety. The accurate and rapid identification of OPNAs is crucial for medical diagnosis and effective treatment. However, distinguishing between various OPNAs and their analogues using on-site point-of-care testing (POCT) remains challenging. Herein, we present a novel Raman-enhanced strategy that employs a chemical capture probe through a structural differential amplification derivative probe coupled with handheld Raman spectrometry. In this method, 2-(dimethylamino methyl)-3-hydroxypyridine (2-DMAMPD) was designed and used to capture target OPNAs in the plasmonic hotspot for the first time. The formation of strong Au-N bonds between nanoparticles and pyridine significantly enhances the cross-section and specific Raman intensity of OPNAs, facilitating effective amplification and differentiation of subtle structural variations among different OPNAs. In practical application, the probe solution can be directly sprayed on the surfaces contaminated by agents, allowing the entire detection process to be completed within five minutes, with a detection limit of 2 ng/mL (equivalent to an absolute content of 50 pg). It is worth noting that during the process of detection, highly toxic OPNAs can be quickly transformed into low-toxic or non-toxic derivatives, which is of great significance for green detection and protection of the operator.