A rapid fluorometric method for determination of aflatoxin B in plant-derived food by using a thioflavin T-based aptasensor.

A fluorometric aptamer-based method is described for the determination of aflatoxin B (AFB). The fluorescent dye thioflavin T (ThT) forms a complex with the aptamer against AFB (aptamer/ThT), and the fluorescence of the complex is strongly enhanced. On addition of AFB, 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 440/487 nm, drops gradually in the AFB concentration range from 0.2 to 200 ng·mL, exhibiting good linearity. The detection limits are 0.2 ng·mL in buffer solution, and 1 ng·mL when applied to plant-derived food. The recovery of AFB from spiked foodstuff ranges from 74.7% to 121%. The assay can be performed within 20 min. Graphical abstract Schematic presentation of label-free thioflavin T (ThT)-based fluorescence aptasensor using aflatoxin B(AFB) aptamer/ThT G-quadruplex complex and the AFB1 aptamer/AFB1 complex fluorescent signal system for the rapid and sensitive detection of AFB1 in soy sauce, spirits, rice, corn and peanuts.