A ternary β-cyclodextrin/carbon nanotube/graphene oxide nanocomposite enables sensitive electrochemical sensing of dinotefuran.

Abstract

Dinotefuran (DNF), a third-generation neonicotinoid insecticide, requires sensitive and reliable residue monitoring in agricultural products. Here, a ternary β-cyclodextrin/carboxylated multi-walled carbon nanotube/graphene oxide (β-CD/MWCNTs-COOH/GO) nanocomposite was developed as a voltammetric sensing interface for DNF. β-CD provides host cavities that can assist interfacial analyte enrichment, while the MWCNTs-COOH establishes conductive pathways within a dimensionally complementary MWCNTs-COOH/GO network. Compared with the corresponding single- and binary-component electrodes, β-CD/MWCNTs-COOH/GO/GCE exhibited the lowest charge-transfer resistance (11.45 Ω) and the largest electrochemically active surface area (0.147 cm2). DNF electroreduction was irreversible, proton-coupled, and diffusion-dominated. Under optimized conditions, the sensor provided two linear ranges of 0.5-5 and 5-70 μM, with a detection limit of 0.05 μM and a sensitivity of 22.89 μA μM-1 cm-2. The sensor showed good fabrication reproducibility and satisfactory tolerance toward common inorganic ions, glucose, ascorbic acid, and thiamethoxam, and retained 92.2% of its initial response after 17 days. Recoveries of 91-102% with RSDs below 4.8% were obtained for cucumber, grape, and potato samples, and the result for spiked cucumber agreed closely with HPLC-DAD analysis. These results support the practical applicability of this simple ternary interface for DNF residue screening.