A novel fluorescent aptasensor for sensitive determination of pesticide was successfully established, using AT-rich three-way junctions (AT-TWJ) DNA stabilized copper nanoparticle (CuNP) as a fluorescent signal and magnetic Fe₃O₄@GO as a single-stranded DNA (ssDNA) adsorbent to reduce the detection background. The detection just involves one strand of dsDNA and two strands of ssDNA. The dsDNA is hybridized by the target aptamer and the partially complementary DNA, acting as a recognition unit. After the specific combination between targets with its aptamer, the released ssDNA and the other two ssDNA can assemble into AT-TWJ DNA. The added Fe₃O₄@GO cannot adsorb the nascent blunt-ended AT-TWJ DNA. Then, the inputting of ascorbic acid (AA) and Cu²⁺ into the supernatant facilitates the formation of AT-TWJ DNA templated CuNPs, generating strong fluorescence. The developed strategy presents a sensitive and specific isocarbophos detection in the linear range of 10–500 nM with a detection limit of 3.38 nM, providing a new path for the detection of pesticides in the fields of food and environmental monitoring.

以富含AT的三向结（AT-TWJ）DNA稳定的铜纳米粒子（CuNP）作为荧光信号和磁性Fe ₃ O ₄ @GO作为单链成功建立了一种新型的灵敏测定农药的荧光适体传感器。DNA（ssDNA）吸附剂可减少检测背景。检测仅涉及一条dsDNA链和两条ssDNA链。dsDNA被靶标适体和充当识别单元的部分互补DNA杂交。在靶标与其适体之间的特定结合后，释放的ssDNA和另外两个ssDNA可以组装成AT-TWJ DNA。添加的Fe ₃ O ₄@GO无法吸收新生的平末端AT-TWJ DNA。然后，将抗坏血酸（AA）和Cu ²⁺输入到上清液中有助于AT-TWJ DNA模板化CuNPs的形成，产生强荧光。制定的策略提出了在10–500 nM线性范围内的灵敏且特异的异小菜碱检出，检出限为3.38 nM，为食品和环境监测领域中的农药检测提供了一条新途径。