Phage-borne peptidomimetics as immunochemical reagent in dot-immunoassay for mycotoxin zearalenone

The advantageous characteristics of phage probes and facility of immunoassays were combined to develop a rapid dot-immunoassay for the mycotoxin zearalenone (ZEN). A peptide library of random 12-mers displayed on phage was panned against anti-ZEN antibody. Selected phage-borne peptidomimetics were used as substitute for coating antigen and applied in dot-immunoassay for rapid detecting of ZEN. The binding specificities and reaction kinetics between selected phages and antibody were analyzed by phage ELISA and surface plasmon resonance, respectively. The equilibrium dissociation constant (KD) measured for selected phage (Z5): antibody was 39.8 nM. The cut-off level for this phage-based dot-immunoassay method of detecting ZEN in cereal samples, assessed visually, was 50 μg kg−1 and the final results can be obtained within 10 min. The validation of the method was performed by analyzing the spiked samples with ZEN at five levels (15, 30, 45, 60, and 75 μg kg−1) and naturally contaminated cereal samples, the results were in good agreement with the obtained by the commercial ZEN ELISA kit. These results suggest that phage can act as a useful immunochemical reagent in dot-immunoassay for toxic small molecules.