A biosensor-based immunoassay for rapid screening of deoxynivalenol contamination in wheat

A surface plasmon resonance (SPR) based indirect inhibitive immunoassay was developed for the rapid quantification of concentrations of the trichothecene mycotoxin deoxynivalenol (DON). A DON-biotin conjugate was synthesized and immobilized to a streptavidin coated SPR sensor surface to measure free anti-DON antibody added to a sample. For analysis, ground wheat was extracted with 10% (v/v) methanol in water with 6% (w/v) polyvinylpyrrolidone, filtered and cleaned up with MycoSep™ columns. Extracts were mixed with a polyclonal anti-DON antibody and pre-incubated prior to injection into a BIAcore®X device. The sensor surface was regenerated with a rinse of 6 M-guanidinechloride in 10 mm-glycine (pH 2.9). The assay had a working range between 0.13 and 10.0 μg ml^-1 of DON, a 50% inhibition concentration (IC₅₀) of 0.72 μg ml^-1, and a detection limit of 2.5 pg μl^-1. Recovery of DON in spiked wheat was 104 ± 15%. The system enables analysis of a sample to be completed in 15 min including sample preparation (10 min) and quantification (5 min). The assay was applied to the analysis of wheat samples with different levels of DON contamination. Statistical analysis revealed a positive, linear correlation between concentrations of DON measured with the new biosensor and GC/MS or HPLC as reference methods. Coefficients of correlation of R² = 0.9464 (GC/MS data) and R² = 0.9066 (HPLC data) were found.