A stem-loop like aptasensor for sensitive detection of aflatoxin based on graphene oxide/AuNPs nanocomposite platform.

Aflatoxin as the potent carcinogenic mycotoxin had been received great attention for detection in food industry and safety. Due to low quantity of aflatoxin in food samples, there is a need to develop a sensitive method toward its detection. In the present study, an aflatoxin B1 (AFB1) specific aptasensor with internal complementary sequence was developed for detection of AFB1. The FAM-functionalized aptamer was deposited on the surface of graphene oxide decorated with gold nanoparticles (GO/AuNPs) and following formation of heteroduplex stem-loop structure led to fluorescence quenching of FAM-labeled aptamer. After incubation of proposed aptasensor with AFB1, the aptamer-AFB1 complex resulted to denaturation in stem-loop structure of aptamer which caused restoration of single strand aptamer and recovery of fluorescence. The assay showed a convenient detection response in the range of 0.5-20 pg/mL with a very low detection limit (0.1 pg/mL) and it was highly selective for AFB1 over other mycotoxins.