Alkaline phosphatase-triggered dual-signal immunoassay for colorimetric and electrochemical detection of zearalenone in cornmeal

Zearalenone (ZEN), as one of the most important foods and feeds pollutant mycotoxins , is threatening human and animal health. Here, we have developed a dual-signal immunoassay triggered by alkaline phosphatase (ALP) for detecting ZEN in cornmeal. The immobilized ZEN-bovine serum albumin and free ZEN in the sample were competitively bound to an anti-ZEN monoclonal antibody (McAb). Then, the ALP labeled goat anti-mouse IgG (ALP-IgG) combined with the McAb. ALP catalyzed ascorbic acid 2-phosphate to produce L -ascorbic acid (AA). AA converted potassium ferricyanide (K 3 [Fe(CN) 6 ]) to potassium ferrocyanide (K 4 [Fe(CN) 6 ]), which reacted with ferric ion (III) to promote the formation of Prussian blue nanoparticles (PB NPs). Consequently, the solution appeared multicolor changes. Meanwhile, PB NPs had a maximum absorption peak at 700 nm. It could be monitored by an UV–vis spectrometer. As an electron transfer medium, K 3 [Fe(CN) 6 ] was consumed gradually along with PB NPs formation. Therefore, electrochemical detection was also used for detecting ZEN. Under the optimum conditions, the logarithm of ZEN concentration showed a good linear relationship with the absorbance from 0.2 to 0.8 ng/mL (R 2 = 0.987) and the differential pulse voltammetry peak current from 0.125 to 0.5 ng/mL (R 2 = 0.993). The limits of detection of colorimetric and electrochemical methods were 0.04 and 0.08 ng/mL, respectively. The recovery rates of ZEN from cornmeal samples were in the range of 80–120%, and relative standard deviations were lower than 10%. The results demonstrated that the dual-signal immunoassay has a high sensitivity for ZEN detection in corn samples.