Electrochemical immunosensor array using a 96-well screen-printed microplate for aflatoxin B1 detection.

A novel analytical immunosensor array, based on a microtiter plate coupled to a multichannel electrochemical detection (MED) system using the intermittent pulse amperometry (IPA) technique, is proposed for the detection of aflatoxin B1 (AFB1). In the present work, the electrochemical behaviour and electroanalytical performance of the thick-film carbon sensors (also designated as screen-printed electrodes) incorporated in the multichannel electrochemical plate were first evaluated. Then the 96-well screen-printed microplate was modified in accord with a competitive indirect enzyme-linked immunoassay (ELISA) format for aflatoxin B1 detection. The measurements were performed using both spectrophotometric and electrochemical procedures and the results of the calibration curves, detection limit (LOD), sensitivity and reproducibility of the respective assay systems were evaluated. The immunoassay was then applied for analysis of corn samples spiked with AFB1 before and after the extraction treatment, in order to study the extraction efficiency and the matrix effect, respectively. These studies have shown that using this system, AFB1 can be measured at a level of 30 pg/mL and with a working range between 0.05 and 2 ng/mL. Good recoveries (103+/-8%) were obtained, demonstrating the suitability of the proposed assay for accurate determination of the AFB1 concentration in corn samples. The specificity of the assay was assessed by studying the cross-reactivity of PAb relative to AFB1. The results indicated that the PAb could readily distinguish AFB1 from other aflatoxins, with the exception for AFG1.