Aptasensor based on entropy-driven catalytic amplification system for sensitive detection of acetamiprid in Chinese herbal medicine

The traditional method of acetamiprid residue detection is difficult to operate, time-consuming and laborious, and requires high professional knowledge of the detection personnel, which can no longer meet the rapid detection in the field. For this reason, a colorimetric aptasensor based on an entropy-catalyzed amplification system was developed for the ultrasensitive and selective determination of acetamiprid. In the absence of acetamiprid, the aptamer and cDNA build a double-stranded structure. The formed hemin/G-quadruplex mimicking DNAzyme can catalyze the substrate ABTS to generate the colored ion ABTS- with the help of H2O2, and the solution turns blue-green. On the contrary, the presence of acetamiprid triggers the release of cDNA, which in turn initiates the entropy-driven system, resulting in the inability to form DNAzyme and therefore no blue-green production of the solution. The quantity of acetamiprid determined the color period. Under the optimal experimental conditions, the method showed a linear correlation (R2=0.9837) for the detection of acetamiprid over the concentration range of 0.1 ~ 100 ng/mL, with a limit of detection of 0.06 ng/mL.The method was used for the determination of acetamiprid in spiked Coix lacryma and bitter almond, with the recoveries in the range of 90.3% ~ 110.3%. The proposed enzyme-free and label-free assay can be developed into a simple, sensitive and rapid detection platform.