A Field-Deployable Multimodal Device Integrated with Paper Strips and LIG Platforms for Rapid Optical–Electrochemical Detection of Organophosphate Nerve Agent Simulants

Abstract

Organophosphorus (OP) nerve agents, including diethylchlorophosphate (DCP) and diethylcyanophosphate (DCNP), represent persistent threats to both human health and environmental safety. The sustainable detection and detoxification of these highly toxic compounds remain a critical global challenge. In this study, we introduce a triphenylamine (TPA)-Bisindolyl methane (BIM) based probe capable of differentiating between two structurally similar nerve agent mimics, diethylchlorophosphate (DCP) and diethylcyanophosphate (DCNP) in semi-aqueous media. The probe self-assembles into nanoscopic aggregates in aqueous environments, yielding dual emission from monomeric and aggregated species. Upon exposure to DCP, rapid hydrogen-bond-assisted aggregation induces a ~21.5-fold fluorescent ‘turn-on’ response, a distinct pink-to-purple colorimetric change, with a low detection limit of 0.14 µM. In contrast, DCNP elicits only weak aggregation and minimal fluorescence modulation, permitting unambiguous differentiation. Additionally, the probe also promotes hydrolytic conversion of DCP to diethyl phosphoric acid, an environmentally benign product, thereby providing sustainable remediation of toxic nerve-agent simulants. Beyond optical sensing, the analytical scope of the probe was expanded to electrochemical detection by immobilizing it onto laser-induced graphene (LIG) electrodes, which provided sensitive and interference-resistant electrochemical sensing. Additionally, pre-coated paper strips and dipstick assays allowed rapid, portable colorimetric and vapor-phase detection of DCP. Collectively, this multimodal and sustainable platform provides a scalable, water-compatible approach for real-time monitoring and detoxification of organophosphorus contaminants in environmental and defense applications.