Colorimetric aptasensor for on-site detection of acetamiprid with hybridization chain reaction-assisted amplification and smartphone readout strategy

An instruments-free colorimetric assay is established for acetamiprid detection with hybridization chain reaction (HCR)-based amplification strategy. Hairpin probes help gold nanoparticles (AuNPs) to resist salt-induced aggregation through sticky ends. In the presence of acetamiprid, aptamer hairpin probe HP opens due to the specifical recognition, then triggers an explosive hybridization between hairpin probes HA-1/2 and numerous hairpin probes are consumed. With the depletion of hairpin probes, the protection weakens and AuNPs suffer from salt-induced aggregation, which results in a color change from pinkish purplish to blue-purple. Under optimal conditions, the assay exhibits high sensitivity for acetamiprid analysis with a detection limit at 1.74 μM. Meanwhile, the aptasensor displays excellent selectivity that only acetamiprid can trigger the HCR and achieve enhanced detection. Worthwhile, based on the color variation, a smartphone readout-based strategy is proposed for visual quantification of acetamiprid, and good practical performance is obtained in real agricultural samples. The above visual method is portable and economic that get rid of advanced instruments, and shows a promising application prospect for on-site detection of acetamiprid.