Rapid lateral-flow immunoassay for the quantum dot-based detection of puerarin

In this study, a rapid (within 10 min) quantitative lateral-flow immunoassay using a quantum dots (QDs)-antibody probe was developed for the analysis of puerarin (PUE) in water and biological samples. The competitive immunoassay was based on anti-PUE monoclonal antibody conjugated with QDs (detection reagent). Secondary antibody was immobilized on one end of a nitrocellulose membrane (control line) and PUE-bovine serum albumin conjugate was immobilized on the other end (test line). In the quantitative experiment, the detection results were scanned using a membrane strip reader and a detection curve (regression equation: y=−0.11 ln(x)+0.979, R2=0.9816) representing the averages of the scanned data was obtained. This curve was linear from 1 to 10 μg/mL. The IC50 value was 75.58 ng/mL and the qualitative detection limit of PUE was 5.8 ng/mL. The recovery of PUE added to phosphate-buffered saline and biological samples was in the range of 97.38-116.56%. To our knowledge, this is the first report of the quantitative detection of a natural product by QDs-based immunochromatography, which represents a powerful tool for rapidly screening PUE in plant materials and other biological samples.