Development of an electrochemical immunosensor to determine zearalenone in maize using carbon screen printed electrodes modified with multi-walled carbon nanotubes/polyethyleneimine dispersions

Abstract

An electrochemical immunosensor is developed to determine zearalenone (ZEA) mycotoxin in maize samples. It is based on the use of a composite, which was prepared from anti-ZEA poly-clonal antibody bonded to gold nanoparticles immobilized on multi-walled carbon nanotubes/polyethyleneimine dispersions. Carbon screen printed-electrodes (CSPE) were used in the electrochemical transduction stage. The immunoassay is based on a direct competitive assay between ZEA in maize samples and ZEA labeled with horseradish peroxidase enzyme (ZEA-HRP). ZEA determination was performed by amperometry, using an applied potential of −0.3 V. The H2O2, which was not consumed by HRP, was reduced at the electrochemical immunosensor surface. Thus, the reduction current was proportional to the amount of ZEA present in samples. All experimental variables involved in the construction of the electrochemical immunosensor were optimized. The linear concentration range is from 1 × 10−4 to 1 × 10−1 ng mL−1. The limit of detection and SC50 were 0.15 pg mL−1 and 2 pg mL−1, respectively. In addition, an acceptable accuracy, with a percentual coefficient of variation (%CV) less than 20%, and recovery percentages close to 105% were found. The electrochemical immunosensor has great advantages such as no pre-treatment of the sample is required, the sample volume is of 20 μL, the experiments require short times and a very low limit of detection is obtained. Results obtained with this electrochemical immunosensor were compared with those determined by HPLC-fluorescence detection, obtaining a very good correlation. The proposed immunosensor is a valuable alternative tool to determine ZEA in maize samples.