Non-competitive immunoassay for low-molecular-weight contaminant detection in food, feed and agricultural products: A mini-review

Immunoassays have gained considerable attention in safety assurance for food, feed and agricultural products. Generally, immunoassays are presented either in a competitive or non-competitive, sandwich-type format, and the former is extensively employed for low-molecular-weight contaminants, which usually bear one accessible epitope. Theoretically, non-competitive, sandwich-type immunoassays have higher sensitivity, precision and linearity. However, the analyte to be measured in such a format must be large enough to have at least two epitopes to be captured. It is not feasible to detect low-molecular-weight contaminants through conventional non-competitive sandwich-type immunoassay. Consequently, there is a trend to develop new types of sensitive non-competitive immunoassays for low-molecular-weight contaminants. This article reviews the progress in non-competitive immunoassays for low molecular weight contaminants in food, feed and agricultural products, including the principles, applications and suggested perspectives for this field. Anti-metatype antibody-based immunoassays are the most promising method, but dissociation of the antibody-hapten complex might be a challenge, and therefore more in-depth research should be focused on preparation of new formats of the antibody-hapten complex. Meanwhile, strategies for direct non-competitive detection or aimed at the simultaneous detection of different targets would be especially desirable besides focusing on improving the sensitivity and specificity of the detection.