Colorimetric and photothermal double-model immunochromatographic assay based on MoS2@Au nanocomposite for high sensitive detection of imidacloprid in food

In this work, a colorimetric and photothermal double-model immunochromatographic assay for the detection of imidacloprid (IMI) was developed using gold nanoparticles (AuNPs) deposited on two-dimensional layered molybdenum disulphide nanosheets (MoS2 NSs). Here, as a signal amplification carrier, the AuNPs on the surface of MoS2 NSs can be well connected with antibody to prepare the photothermal signal probe, this probe has good biocompatibility and high heat conversion efficiency. It is worthing mentioning that the assay realizes the double-mode signal output of semi-quantitative visual detection and quantitative photothermal detection under 808 nm excitation. Under optimal conditions, the limit of detection (LOD) of assay based on photothermal model for IMI was 0.18 μg L-1 and the visual limit of detection (vLOD) of assay based on colorimetric model was 12 μg L-1. The proposed assay has good specificity and other neonicotinoid pesticide analogues have no effect on assay performance. The detection results of this assay were consistent with that of HPLC, indicating the good accuracy of this proposed quantitative detection method. This double-model assay can be used as a promising candidate for sensitive and rapid detection of IMI, which provides a new strategy for real-time monitoring of pesticide residues in food safety test.