RecJf exonuclease-assisted fluorescent self-assembly aptasensor for supersensitive detection of pesticides in food

Fluorescence quenching induced by exonuclease, specific target recognition by an aptamer, and host-guest recognition were artfully integrated in this study, and a new nanoscale fluorescent aptasensor for supersensitive recognition of acetamiprid was proposed. In the absence of acetamiprid, the aptamer hybridized with complementary DNA at 3'end-marked fermcene (Fc) (cDNA-Fc) to form a double-stranded DNA. Fluorescence intensity was nearly unchanged after RecJf exonuclease was added. After the addition of acetamiprid, the aptamer preferentially bound with it to form a new compound; hence, the aptamer could not bind with cDNA-Fc. The single-stranded aptamer and cDNA-Fc were cut off after RecJf exonuclease was added, and the Fc released via host-guest recognition rapidly entered the cavity of cyclodextrin and initiated photoinduced electron transfer. Consequently, fluorescence intensity decreased, and acetamiprid was sensitively detected. The method can be extensively applied to detect various pesticides or additives in agriculture and forestry.