Quantum dot-based lateral-flow immunoassay for rapid detection of rhein using specific egg yolk antibodies

The lateral-flow immunoassays based on novel fluorescent labels have been receiving increasing attention. Here, we developed a rapid, quantitative, lateral-flow immunoassay for rapid and accurate detection of rhein (RHE). The competitive immunoassay used anti-RHE IgY (immunoglobulin of yolk) probe conjugated with QDs as reporter. Our results showed that the immunochromatographic strip can be applied for qualitative and quantitative analysis of RHE in samples. For quantitative analysis, the strips were scanned by a membrane-strip reader, and a detection curve (y = -0.128ln(x) + 1.7627, correlation coefficient = 0.9792) representing the averages of the scanned data was obtained. The detection range was 80-5000 ng mL^-1 and the qualitative-detection limit for RHE was 98.2 ng mL^-1. To our knowledge, this is the first report of the quantitative detection of a natural product by QDs-IgY immunochromatography, which creates a new strategy to detect the harmful or index component of TCM and may be applied as a supplement or alternative to instrument detection.