Design of fluorescent self-assembled multilayers and interfacial sensing for organophosphorus pesticides

This paper details the fabrication of indole (ID) self-assembled multilayers (SAMs) and fluorescence interfacial sensing for organophosphorus (OP) pesticides. Quartz/APES/AuNP/l-Cys/ID film was constructed on l-cysteine modified Quartz/APES/AuNP surface via electrostatic attraction between ID and l-cysteine. Cyclic voltammetry indicates that ID is immobilized successfully on the gold surface. Fluorescence of the Quartz/APES/AuNP/l-Cys/ID film shows sensitive response toward OPs. The fluorescent sensing conditions of the SAMs are optimized that allow linear fluorescence response for methylparathion and monocrotophos over 5.97 × 10−7 to 3.51 × 10−6 g L−1 and 3.98 × 10−6 to 3.47 × 10−5 g L−1, with detection limit of 6.1 × 10−8 gL−1 and 3.28 × 10−6 gL−1, respectively. Compared to bulk phase detection, interfacial fluorescence sensing based on the SAMs technology shows higher sensitivity by at least 2 order of magnitude.