An innovative immunochromatography assay for highly sensitive detection of 17β-estradiol based on an indirect probe strategy

Ultrasensitive and fast screening of small molecule contaminants by immunochromatography assay (ICA) is still challenging in field conditions. Here, a novel indirect probe based ICA (ipICA) for highly sensitive detection of 17 beta-estradiol (E2) was introduced. The strategy was achieved using carboxyl modified Fe3O4 magnetic nanoparticles (MNPs) to label goat anti-mouse antibody (GAMA). The free anti-E2 monoclonal antibody (mAb) rather than labeled mAb was adopted to capture E2 molecules. For comparison, MNPs-based traditional and dual-probe ICAs were also prepared. This strip sensor demonstrated higher sensitivity, with a lowest visible detection limit of 0.2 ng mL(-1), which was 5 and 2 times better than that of the MNPs-based traditional strip and dual-probe strip, respectively. The outstanding performance of this novel sensor mainly benefited from the decreased amount of free mAb and the signal amplification of this strategy. Additionally, this method was successfully applied in the detection of E2 in milk, prawn, fish and chicken samples. The proposed sensor exhibited acceptable accuracy for on-site detection of target analyte in food safety monitoring, also has potential applications for the other small molecule contaminants.