Fluorometric determination of aflatoxin B1 using a labeled aptamer and gold nanoparticles modified with a complementary sequence acting as a quencher.

A fluorometric aptamer based assay is described for rapid and sensitive detection of aflatoxin B1 (AFB1). It is making use of a fluorescein (FAM) labeled anti-AFB1 aptamer and complementary DNA-modified gold nanoparticles (GNPs). In the absence of AFB1, the FAM-labeled aptamers hybridize with complementary DNA strands that were covalently immobilized on GNPs. This results in quenching of the green fluorescence (with excitation/emission peaks at 485/525 nm). In the presence of AFB1, the aptamer probe binds AFB1 and is released from the GNPs. Hence, fluorescence is restored. Under optimized conditions, AFB1 in the concentration range from 61 pM to 4.0 µM can be detected, and the detection limit is 61 pM. This assay is highly selective for AFB1. It was applied to the determination of AFB1 spiked into 50-fold diluted wine and 20-fold diluted beer. Graphical abstract Schematic presentation of fluorometric detection of AFB1 using a fluorescein (FAM) labeled anti-AFB1 aptamer and complementary DNA-modified gold nanoparticles (GNPs).