Mesoporous immunosensor applied to zearalenone determination in Amaranthus cruentus seeds

Abstract

We describe an electrochemical immunosensor for zearalenone (ZEA) determination in Amaranthus cruentus seeds by an enzyme immunoassay sandwich type. The device is based on a screen-printed carbon electrode (SPCE) modified with amino mesoporous silica (MCM-41) synthetized with Fe2O3 in situ. Mesoporous material enlarges the surface available for anti-ZEA antibodies immobilization. SPCE/MCM-41-Fe2O3 was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and cyclic voltammetry. ZEA in the sample previously pretreated was recognized and captured by anti-ZEA on SPCE/MCM-41-Fe2O3. Then, the horseradish peroxidase (HRP)-conjugated anti-ZEA-antibody was added, and the substrate solution (H2O2 + 4-terbutylcatechol (4-TBC)) reacted with the HRP that catalyzed the oxidation of 4-TBC to 4-terbutylbenzoquinone (TBQ). Finally, the enzymatic product was detected at −100 mV, and the current was proportional to the ZEA present in the sample. The calibration plot exhibited a linear range from 1.88 to 45 ng mL−1, and the limit of detection was 0.57 ng mL−1 (r2 = 0.998). The coefficient of variation inter- and intra assay was below 6%. Our method achieved a good selectivity, stability and reproducibility for ZEA detection in A. cruentus seeds.