An ultrasensitive and switch-on platform for aflatoxin B 1 detection in peanut based on the fluorescence quenching of graphene oxide-gold nanocomposites

Abstract Graphene oxide-gold nanocomposites (GO/AuNCs) were prepared and used as a novel fluorescence quenching platform for ultrasensitive detection of aflatoxin B 1 (AFB 1 ) coupled with hybridization chain reaction (HCR) amplification. In the designed system, two fluorophore labeled hairpin probes (HP 1 /HP 2 ) were introduced, and the fluorescence signals of them were effectively quenched due to the adsorption on GO/AuNCs. Associate probe (AP) was used for the specific recognition of AFB 1 , and the stem-loop structure of it was opened. Meanwhile, the exposed section of AP was utilized as an initiator for the happen of HCR between HP 1 and HP 2 , a strong fluorescence signal was obtained due to the formation of long nicked dsDNA duplex and desorbed of them from the surface of GO/AuNCs. Under the optimal conditions, GO/AuNCs displayed 94% of the quenching efficiency to the fluorescent probes, and a detection limit down to 0.03 pg/mL was obtained for AFB 1 detection. In particular, the assay exhibited excellent selectivity for the detection of AFB 1 against other interfering agents that normally coexist with AFB 1 in mildewed agriculture products. Moreover, the assay could realize the detection of AFB 1 effectively in peanut samples.