A mimotope peptide-based dual-signal readout competitive enzyme-linked immunoassay for non-toxic detection of zearalenone.

In this study, a mimotope peptide-based non-toxic photoelectrochemical (PEC) competitive enzyme-linked immunoassay (ELISA) was established for ultrasensitive detection of zearalenone (ZEN) with dual-signal readout. Using the phage display technique (PDT), a mimotope peptide of ZEN could be harvested by selecting a peptide from a phage-display peptide library, which avoided using mycotoxin itself and minimized potential damage to operators. The tyramine-modified rutile TiO mesocrystals (Tyr-RMC) with outstanding PEC properties were utilized as reporter units to label the mimotope peptide. The fabricated peptide@Tyr-RMC probe could anchor on the antibody-modified electrode via competitive immune recognition of free target ZEN. When subjected to catalysis of HRP-HO, the Tyr-RMC composite was deposited at the enzyme reaction site, causing rolling circle extension of the reporter unit chains. By merit of the brilliant signal amplification effect of tyramine signal amplification (TSA), dramatically enhanced photocurrent response and enormously increased electrochemical impedance could be determined. Combining all of these advantages, the developed dual-signal readout non-toxicity immunoassay could effectively decrease environmental interference. Also, the designed dual-signal readout biosensor demonstrated a wide linear range between 10 and 1 ng mL with a low detection limit of 1 × 10 ng mL, which provides a valuable reference for developing highly efficient, secure and sensitive detection methods and indicates promising applicability in food testing.