A fluorescent immunochromatographic strip test using Quantum Dots for fumonisins detection.

A fluorescent immunochromatographic strip test (ICST) based on the use of Quantum Dots (QD) was developed and applied to detect fumonisins in maize samples. A limit of detection for fumonisin B1 of 2.8 µg L(-1) was achieved, with an analytical working range of 3-350 µg L(-1), corresponding to 30-3500 µg kg(-1) in maize flour samples, according with the extraction procedure. The time required to perform the analysis was 22 min, including sample preparation. Recovery values in the range from 91.4% to 105.4% with coefficients of variation not exceeding 5% were obtained for fortified and naturally contaminated maize flour samples. To evaluate the possible improvements due to the use of QD for ICST technology, we performed a direct comparison of the proposed QD-ICST to a gold nanoparticles- and a chemiluminescent-ICST previously developed for fumonisins detection, in which the same immunoreagents were employed.

Novel multiplex fluorescent immunoassays based on quantum dot nanolabels for mycotoxins determination.

The aim of this manuscript was the development of easy-to-operate quantum dots (QDs)-based immunochemical techniques for simultaneous screening of several mycotoxins in cereals. Two different approaches for multiplex fluorescent immunosorbent assay (FLISA) were employed. In the first approach a multiwell plate in which the different wells express a different mycotoxin (deoxynivalenol, zearalenone, aflatoxin B1, T2-toxin and fumonisin B1) was considered as a multiplex because each sample was pretreated once and then will be distributed over a series of wells within the same plate (single-analyte multiplex, SAM). The entire assay allows the simultaneous determination of all compounds. For the double-analyte multiplex (DAM) two different specific antibodies were co-immobilized in one single well. Zearalenone and aflatoxin B1 were simultaneously determined, provided their conjugates are labeled with QDs which are fluorescent in different parts of the spectrum, by scanning the assay outcome at two different wavelengths. The limits of detection (LOD) for the simultaneous determination of deoxynivalenol, zearalenone, aflatoxin B1, T2-toxin and fumonisin B1 by SAM FLISA were 3.2, 0.6, 0.2, 10 and 0.4 µg kg(-1), respectively, while for the DAM FLISA they were 1.8 and 1 µg kg(-1) for zearalenone and aflatoxin B1, respectively. SAM FLISA principle was also presented in a qualitative on-site format and tested for on-site multiplex determination of four mycotoxins in cereals. The achieved cut-off values of 500, 100, 2 and 100 µg kg(-1) for deoxynivalenol, zearalenone, aflatoxin B1 and T2-toxin respectively. For simplification of multiassay results' evaluation the conjugates with QDs of different colors were used.