Novel chemiluminescent immunochromatographic assay using a dual-readout signal probe for multiplexed detection of pesticide residues†
A novel immunochromatographic assay (ICA) using a dual-readout signal probe was developed for multiplexed detection of pesticide residues by adopting methyl parathion and fenpropathrin as model analytes. Luminol-reduced Au nanoparticles (LRAuNPs) were synthesized and utilized in the proposed ICA platform as a colorimetric/chemiluminescent (CL) dual-readout probe. The methyl parathion antibody and fenpropathrin antibody were tagged with the prepared LRAuNPs to conduct spatially-resolved multiplexed detection. After the occurrence of two immunoreactions on the test strip, the probes were captured by the immobilized antigens on the two test zones. The red color resulting from the accumulation of captured LRAuNPs was adopted as the visual and semi-quantitative readout. For the sensitive quantitative detection of the analytes, the CL signals caused by the luminophore in the LRAuNPs were collected after triggering the luminol-H2O2 CL reaction. Under the optimal conditions, the detection limits for methyl parathion and fenpropathrin were 0.17 ng mL−1 and 0.10 ng mL−1 (S/N = 3), respectively. The whole procedure for ICA was completed within 15 min. The present ICA protocol was successfully applied for detection of pesticide residues in spiked traditional Chinese medicine samples. This dual-readout ICA platform showed merits such as low cost, time efficiency, easy operation and high sensitivity. Its application potential has been demonstrated in the rapid screening and field detection of multiple pesticide residues.