A sensitive lateral flow immunochromatographic strip with prussian blue nanoparticles mediated signal generation and cascade amplification

This work reports a low-cost, fast and highly sensitive lateral flow immunoassay (LFIA) platform with Prussian blue nanoparticle (PBNP) as a new reporter, which efficiently mediates an on-demand cascade signal amplification by catalyzing oxidation of chromogenic reagent 3,3′,5,5′-tetramethylbenzidine (TMB). In this case, PBNPs are accumulated on the test line through the specific immune interaction, resulting in a blue-colored line. The colorimetric signal can be further amplified via the peroxidase mimic PBNP-catalyzed TMB oxidation to produce an insoluble blue-violet precipitate. Under an optimal condition, a limit of detection (LOD) at 10 pg mL −1 is achieved for rabbit IgG (RIgG) detection, which is 2–3 orders of magnitude better than the conventional LFIA strip using colloidal gold nanoparticle as a label. A macromolecular RIgG and a small molecular mycotoxin ochratoxin A (OTA) are also successfully analyzed in mimicking samples, demonstrating its good practicability of the proposed platform in a variety of fields.