Electrochemical Aptasensor Based on Porous Reduced Graphene Oxide and Au@Fe3O4 Shell-Core Structure for Detection of Thiamethoxam in Green Leafy Vegetables

Abstract

In this work, a novel electrochemical aptasensor based on porous reduced graphene oxide (PrGO) and Au@Fe3O4 composites was constructed for the detection of thiamethoxam (TMX) in green leafy vegetables. PrGO was prepared by etching method, and the formed porous structure effectively overcame the problem of easy aggregation of graphene, and improved the specific surface area. The Au@Fe3O4 shell-core structure was synthesized, which organically combined the easy surface modification properties of gold nanoparticles with a large specific surface area of Fe3O4, providing a favorable loading interface for the immobilization of biological recognition elements. In addition, the composites of PrGO and Au@Fe3O4 showed a significant synergistic effect, effectively promoting the electron transfer and improving the electrochemical performance. Sulfhydryl-modified aptamer was used as a recognition elements to specifically recognize TMX. The constructed aptasensor exhibited a wide linear detection range of 0.1–1000 ng ml−1 and a limit of detection of 0.03 ng ml−1 (S/N = 3). The aptasensor also showed good stability, reproducibility and selectivity.