A novel exonuclease III‐based turn‐on fluorescent aptasensor for aflatoxin B1 detection

Abstract

AbstractBackgroundAflatoxin B1 (AFB1) is strongly carcinogenic and has been classified as a class I carcinogenic compound by the International Agency for Research on Cancer. AFB1 is widely contaminated in wheat, peanuts, corn and other crops and their products, posing a great threat to human health.ObjectiveTo establish a rapid, safe and accurate fluorescent aptasensor for sensitive detection of AFB1 in food.MethodsIn this study, single‐stranded DNA (S1) labeled with black hole quencher BHQ1 and carboxyfluorescein FAM at both ends was used as a signal probe. Nucleic acid exonuclease III (EXO‐III) was introduced as a signal amplification strategy. The basic principle is to exploit the fluorescence resonance energy transfer (FRET) effect generated between FAM and BHQ1. The fluorescent signal change of FAM in the presence or absence of the target is used for the quantitative detection of AFB1. And on this basis, the factors affecting the sensitivity of the sensor are explored in depth.ResultsUnder optimal experimental conditions, the sensor showed a good linear relationship between LgCAFB1 and relative fluorescence intensity in the range of 0.05‐500 ng/mL. The detection limit was as low as 18.2 pg/mL. In particular, the best performance of the aptasensor was achieved when the ratio of cDNA to Apt was 1.2 and the amount of EXO‐III was 25 U.ConclusionsThe combination of MBs, dual‐labeled S1 probes and Exo‐III was used to develop an accurate and sensitive fluorescent aptasensor for AFB1 detection. The developed aptasensor has satisfied recovery and selectivity in AFB1 detection of corn flour and wine samples, indicating that the designed aptasensor has the potential to be used in detecting AFB1 of food samples.