Ultrasensitive and simultaneous monitoring of multiple small-molecule pollutants on an immunochromatographic strip with multilayered film-like fluorescent tags

A wide variety of small-molecule pollutants is harmful to human health, and their highly sensitive universal and rapid detection in complex environments remains a challenge. Herein, a multiplexed and ultrasensitive immunochromatographic strip (ICS) was developed for the universal analysis of three kinds of different pollutants based on multilayered fluorescent nanofilm-guided signal amplification. Flexible three-dimensional nanofilms (GO–MQD) with large surface areas, high quantum dot (QD) loading, superior luminescence, and good stability were synthesized through the electrostatic adsorption-mediated layer-by-layer assembly of three layers of small QDs onto two-dimensional graphene oxide (GO) nanosheets, modified with specific antibodies, and utilized as enhanced fluorescent tags in the ICS method for quantitative target detection. By combining the GO–MQD nanofilms and multiplexed ICS, the proposed assay can rapidly and sensitively detect aflatoxin B1, clenbuterol, and kanamycin in actual samples/environmental samples (pork extract, milk, river water, and lake water) with low detection limit (0.87, 2.04, and 0.81 pg/mL), fast testing time (15 min), good stability and high reproducibility (RSD