Abstract: In this study, a highly sensitive and selective electrochemical aptamer sensor (6-mercapto-1-hexanol (MCH)/Apt/AuNPs/rGO-PANi) for acetamiprid (ACE) was prepared based on Au nanocomposites (AuNPs)/reduced graphene oxide (rGO)-polyaniline (PANi). The morphology and structure of the synthesized nanomaterial and the interface of different electrodes were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM)/ energy dispersive X-ray spectrometry (EDX). The electrochemical properties of different electrodes were studied by cyclic voltammetry and electrochemical impedance spectroscopy, and it was found that the AuNPs/rGO-PANi modified electrode showed a large electrochemical active area and excellent electrochemical properties, which could provide an ideal platform for aptamer fixation and electrochemical sensing of ACE. Under optimal conditions, the linear range of MCH/Apt/AuNPs/rGO-PANi for ACE detection was 1.0–100 000.0 ng/L, and the detection limit was 0.15 ng/L at a signal-to-noise (RSN) of 3. A 100-fold excess of common co-existing pesticides did not significantly interfere with the detection of ACE. The prepared aptamer sensor was applied to the detection of cucumbers and sweet potato leaves with recoveries ranging from 94.5% to 98.5%. The accuracy of the developed method was verified by liquid chromatography-mass spectrometry (LC-MS).

Key words: aptamer sensor; acetamiprid; electrochemical impedance method; food analysis