Ultrasensitive magnetic ELISA of zearalenone with pre-concentration and chemiluminescent detection

- An ultrasensitive magnetic ELISA of zearalenone (ZEN) was developed.
- Magnetic nanoparticles allowed to implement the ELISA in a pseudo-homogeneous mode.
- Pre-concentration of ZEN was combined with chemiluminescence detection.
- The developed assay allows detecting up to 4 pg/mL of ZEN.
- The assay provides ZEN control in wine with detection limit of 0.03-0.05 ng/g.

In this study, an enzyme-linked immunosorbent assay (ELISA) of mycotoxin zearalenone (ZEN) based on magnetic iron nanoparticles (MNPs) was developed. Highly dispersed MNPs used as carriers to immobilize anti-ZEN antibodies allowed the immunoassay to be carried out in a pseudo-homogeneous mode through the rapid formation of immune complexes in the reaction media, their separation by a magnetic field, and the heterogeneous detection of the bound peroxidase label. The traditional colorimetric substrate of a peroxidase label was changed to a highly sensitive chemiluminescent one for the detection of specific complexes' formation. The developed analysis consisted of two main stages: first, the interaction of MNP-based immunosorbent with free ZEN in a large-volume sample and its transfer to a smaller volume (preliminary concentration of the analyte) and then binding with ZEN-peroxidase complexes. A proposed novel combination of a 50-fold pre-concentration of ZEN with chemiluminescence detection allows for the determination of zearalenone with the detection limit of 4 pg/mL. Therefore, more than an order of magnitude increase of the assay sensitivity was achieved compared with the same assay format with colorimetric detection (0.06 ng/mL) or chemiluminescent MNP-ELISA without a pre-concentration of the analyte (0.1 ng/mL). The analysis was validated for the determination of zearalenone in wine. An assay based on magnetic concentration and chemiluminescent detection can be proposed as a universal analytical tool for the rapid assessment of food contamination by mycotoxins and other hazardous substances.

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