Stable detection of diazinon residues in vegetables by an electrochemiluminescent aptasensor based on the in-situ production of HO from dual-catalytic glucose.

Stable detection of diazinon (DZN) residues in vegetables is important for food safety. In this work, an electrochemiluminescence (ECL) aptasensor with dual-catalytic glucose in-situ production of HO was constructed for the stable detection of DZN in vegetables. Firstly, MWCNTs@MB was prepared using π-π stacking interactions between methylene blue (MB) and multi-walled carbon nanotubes (MWCNTs) to enhance the loading of MB on an electrode and thus catalyze the generation of HO from glucose. Secondly, CuO@AuNPs was formed by loading AuNPs on the surface of CuO through spontaneous reduction reaction, which improved the interfacial charge transfer, CuO nano-enzyme had glucose oxidase mimicking activity and could further catalyze the production of more HO from glucose. MWCNTs@MB and CuO@AuNPs played a key role in the in-situ generation of co-reacting reagent HO, which solved the problem of unstable detection caused by the easy decomposition of the HO solution added to the luminescence system. In addition, the aptamer was immobilized on the electrode surface by forming Au-S bonds with CuO@AuNPs. As a result, the ECL aptasensor performed good linearity in 1.00 pg mL-1.00 μg mL and a low limit of detection (LOD) to 0.39 pg mL (S/N = 3). This work provided an effective method for the accurate and stable detection of DZN residues in vegetables, which was of great significance in ensuring food safety and assessing the environmental risk of DZN.