RESUMEN
A label-free and enzyme-free aptasensor for sensitive assay of acetamiprid has been established using AT-rich double-stranded (ds) DNA-templated copper nanoparticles (CuNPs) as fluorescent probe. In this work, two hairpin DNA, HP1 and HP2, were elaborately designed with AT-rich DNA sequences in their loops. The aptamer of acetamiprid was located at the 3'-terminal of HP1, which was caged in the stem of HP1. Upon the addition of acetamiprid, the aptamer could combine with acetamiprid to form a target/aptamer complex, and thus its free 5'-terminal was released. Subsequently, the protruded 3'-terminal of HP2 could hybridize with the free 5'-terminal of HP1 to form a stable AT-rich dsDNA. When it interacted with Cu2+ and ascorbic acid (AA), the AT-rich dsDNA/CuNPs were generated with strong fluorescence, offering a "switch-on" detection of acetamiprid. The developed strategy could high selectively detect acetamiprid at the concentration as low as 2.37â¯nM. Moreover, the possibility of this strategy for the food sample analysis was also investigated. The obtained results demonstrate that the developed strategy has a promising application potential for acetamiprid assay in food safety fields.