A specific DNA-assembled framework coupled with graphene‑gold nanocomposite for ratiometric and rapid monitoring of acetamiprid

Monitoring pesticide residues is crucial due to their environmental impact and potential risk to human health. In this study, a highly sensitive and selective ratiometric fluorescent aptasensor was developed for the detection of acetamiprid (ACE) in agricultural products. The sensing platform was constructed using an AuNP-decorated partially reduced graphene oxide (rGO Au) nanocomposite, which acted as an efficient fluorescence quencher. A stem-loop FAM-labeled aptamer was also employed as recognition probe. In the presence of ACE, the stem loop structure of aptamer unfolded, allowing hybridization with a complementary Cy5-labeled probe. This process restored FAM fluorescence while decreasing Cy5 emission due to its closer proximity to the nanocomposite surface, enabling dual-channel ratiometric fluorescence detection. Under optimized conditions, the sensor showed a linear detection range of 6–36 pM with an exceptionally low LOD of 5.08 pM. The aptasensor demonstrated excellent selectivity against structurally similar pesticides and reliable performance in ACE-spiked bell pepper extracts, with analytical recoveries ranging from 85% to 97%. These results highlight the aptasensor's potential as a rapid, sensitive, and practical tool for ACE detection in food safety and agricultural monitoring.