Electrochemical aptasensor based on exonuclease III-mediated signal amplification for sensitive detection of vomitoxin in cornmeal

Abstract

Vomitoxin (DON) residues in grains are of great concern to public health. Herein, a label-free aptasensor was constructed to detect DON distributed in grains. Cerium-based metal-organic framework composite gold nanoparticles (CeMOF@Au) were used as substrate materials to facilitate electron transfer and provided more binding sites for DNA. The separation of DON-aptamer (Apt) complex and cDNA was achieved by magnetic separation technique based on magnetic beads (MBs), ensuring the specificity of the aptasensor. Exonuclease III (Exo III)-assisted cDNA cycling process strategy would be triggered when cDNA was separated and introduced to the sensing interface for further signal amplification. Under optimal conditions, the constructed aptasensor presented a wide detection range from 1 × 10−8 mg·mL−1 to 5 × 10−4 mg·mL−1 for DON, and the detection limit was 1.79 × 10−9 mg·mL−1, including a satisfactory recovery in cornmeal sample spiked with DON. The results showed that the proposed aptasensor had high reliability and promising application potential in detecting DON.