Detection of ochratoxin A by quantum dots–based fluorescent immunochromatographic assay

Ochratoxin A (OTA) is a toxic metabolite produced mainly by Aspergillus and Penicillium species. A quantitative method was developed for the rapid, simple, and sensitive detection of OTA in corn by quantum dots–based fluorescent immunochromatographic assay (QDs-ICA). The CdSe/ZnS QDs–labelled anti-OTA monoclonal antibody (mAb) conjugates were designed as the fluorescent signal probe. The QDs-ICA included the designation of test line (T line) and control line (C line), which were sprayed with optimal concentrations of the OTA-OVA and staphylococcal protein-A (SPA), respectively. Under the optimal experimental conditions, the QDs-ICA exhibited excellent specificity and good accuracy and precision. For qualitative detection, the cut-off value for the T line of the visual detection method was 2.5 ng/mL. For quantitative detection, the linear regression equation of the standard curve was y = 0.366x + 0.514 with a reliable correlation coefficient (R2 = 0.992). Moreover, the 50% inhibition value (IC50) of the QDs-ICA was 0.91 ng/mL, the limit of detection (LOD) was 0.07 ng/mL, and the detection range was 0.05 to 10 ng/mL. In addition, the recovery rates ranged from 91.82 to 100.35% with a coefficient of variation (CV) below 3% for intra-assay, whereas the recovery rates for inter-assay changed from 94.29 to 104.62% with a CV below 10%. These results indicate that the QDs-ICA can serve as a potential large-scale preliminary device for rapid determination of OTA.