Electrochemical enzyme-linked oligonucleotide array for aflatoxin B detection.

In this work, an electrochemical enzyme-linked oligonucleotide array to achieve simple and rapid multidetection of aflatoxin B (AFB) is presented. The assay is based on a competitive format and disposable screen-printed cells (SPCs). Firstly, the electrodeposition of poly(aniline-anthranilic acid) copolymer (PANI-PAA) on graphite screen-printed working electrodes was performed by means of cyclic voltammetry (CV). Aflatoxin B conjugated with bovine serum albumin (AFB-BSA) was then immobilized by covalent binding on PANI-PAA copolymer. After performing the affinity reaction between AFB and the biotinylated DNA-aptamer (apt-BIO), the solution was dropped on the modified SPCs and the competition was carried out. The biotinylated complexes formed onto the sensor surface were coupled with a streptavidin-alkaline phosphatase conjugate. 1-naphthyl phosphate was used as enzymatic substrate; the electroactive product was detected by differential pulse voltammetry (DPV). The response of the enzyme-linked oligonucleotide assay was signal-off, according to the competitive format. A dose-response curve was obtained between 0.1 ng mL and 10 ng mL and a limit of detection of 0.086 ng mL was achieved. Finally, preliminary experiments in maize flour samples spiked with AFB were also performed.