Development and validation of a novel lateral flow immunoassay device for detection of aflatoxins in soy-based foods

Abstract

Aflatoxins (AFs) are natural toxins produced as secondary fungal metabolites. Common in diverse commodities, the consumption of aflatoxin-contaminated foodstuffs has harmful effects on human health mainly due to their carcinogenic effects. There is considerable demand for the development of rapid, reliable and cost-effective screening tools, once regulatory authorities employ strict procedures for detection of aflatoxins. In this study, a sensitive and specific strip test assay was developed, based on a competitive format, for the detection of aflatoxins in soybean, a major Brazilian agricultural commodity. A monoclonal antibody (mAb) was produced, named as 3B6, with high specificity to aflatoxins B₁, M₁, G₁, G₂ and B₂. For the development of a strip test, colloidal gold particles were coated with 3B6 mAb and used as the detector reagent. An AFB₁–BSA conjugate was sprayed at the test line of a nitrocellulose membrane to serve as a competitor reagent, with an anti-species-specific antibody used at the control line. The strip test developed was capable of detecting as little as 0.5 μg kg⁻¹ of aflatoxin. To validate the strip test, soybean grains infected and non-infected with the aflatoxin-producing fungus Aspergillus flavus were employed. The applicability of the developed test was demonstrated by screening 12 foodstuff samples (soy protein and soy milk) collected from different local markets. The results indicated that the strip tests developed were capable of accurately qualitatively identified aflatoxin-contaminated samples in less than 10 min. This method offers a promising device for application in routine monitoring during storage, transport, processing and handling of agricultural commodities.