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

Background: 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, sandwichtype 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. Scope and approach: 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. Key findings and conclusions: 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 noncompetitive 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.