High sensitive immunoassay for multiplex mycotoxin detection with photonic crystal microsphere suspension array.

A novel, sensitive, and high throughput competitive immunoassay for multiplex mycotoxins was established by immobilizing the artificial antigens (Ags) of mycotoxins on the surfaces of three kinds of silica photonic crystal microsphere (SPCM) suspension arrays. The SPCMs were encoded by their reflectance peak positions. Aflatoxin B1 (AFB1), fumonisin B1 (FB1), and citrinin (CIT) spiked in the cereals were extracted, and the fluorescein isothiocyanate (FITC) labeled antibodies (Abs) of these mycotoxins were added into the centrifuge tube which contained the SPCMs of the modified artificial antigens (Ags). The fluorescence signal was collected by an array fluorescent scanner. The limit of detection (LOD) was as low as 0.5, 1, and 0.8 pg/mL for AFB1, FB1, and CIT, respectively. The new method provided a wide linear detection range from 0.001 to 10, 0.001 to 10, and 0.001 to 1 ng/mL for AFB1, FB1, and CIT, respectively. The mean recovery rates are in range of 74.7 ± 4.0% to 127.9 ± 4.4% for the three mycotoxins in corn, peanuts, and wheat. The developed method for mycotoxins was used to assay the AFB1, FB1, and CIT level in 10 naturally contaminated cereal samples, and the results of detection were in agreement with that of a classic enzyme-linked immunosorbent assay (ELISA) method. This method saves a large amount of reagents (10 μL volume) and detection time (<3 h) for multiplex mycotoxin assay.