CdAgAlloy@polymer dots of Biginelli polyamide for the highly sensitive and selective recognition of nerve agent mimics in an aqueous and vapor phase

Abstract

In today's world, toxic nerve agents pose a significant threat to humankind, and their detection methodology requires an advanced, facile method with a rapid response that is also handy and economical. For the first time, we fabricated bimetallic CdAg alloy over a Biginelli-based non-conjugated polymer dot (Pdot) surface, with chemical reduction in water. The fabricated CdAgAlloy@Pdots were then fully characterized by the use of physicochemical techniques. The modified surface of the Pdots resulted in increased activity and selectivity, and decreased inter-Pdot distance, with generated surface conductivity towards polar organophosphates. The conductive surface was able to selectively bind polar diethylchlorophosphate (DCP) and diethylcyanophosphonate (DCNP), which are nerve agent mimics, through weak interactions such as dipole–dipole or H-bonding interaction. The sensing mechanism was demonstrated by transmission electron microscopy (TEM), FT-IR, 31P NMR images, and cyclic voltammetry (CV) studies. The limit of detection of the sensor for DCP and DCNP was 0.85 nM and 1.2 nM, respectively. In the presence of DCP, the blue color of CdAgAlloy@Pdots changed to fluorescent greenish-yellow under UV light at 365 nm. Based on these results, we fabricated economic test paper strips for an instant, rapid, and sensitive vapor phase detection of DCP that occurred within a few seconds. Hence, we incorporated many key innovations for DCP detection into the formation of bimetallic CdAg alloy@Pdots, which possess long-term economic and sustainable features for real-world sensing applications.