A rapid fluorometricmethod for determination of aflatoxin B1 in plant-derived food by using a thioflavin T-based aptasensor

A fluorometric aptamer-based method is described for the determination of aflatoxin B-1 (AFB(1)). The fluorescent dye thioflavin T (ThT) forms a complex with the aptameragainst AFB(1) (aptamer/ThT), and the fluorescence of the complex is strongly enhanced. On addition of AFB(1), it will bind to the aptamer and release ThT. The fluorescence of free ThT is much weaker. The fluorescence of the system, best measured at excitation/emission wavelengths of 440/487nm, drops gradually in the AFB(1) concentration range from 0.2 to 200ng mL (-1), exhibiting good linearity. The detection limits are 0.2ng mL (-1) in buffer solution, and 1ng mL (-1) when applied to plant-derived food. The recovery of AFB(1) from spiked foodstuff ranges from 74.7% to 121%. The assay can be performed within 20min.