Promoting Electron Transfer Kinetics and Adsorption Capacity for the Detection of Furazolidone in Real Food Samples by Using Ag-core@Fe3O4-Shell-Based Electrochemical Sensing Platform

In this study, the preparation of core/shell Ag@Fe 3 O 4 nanoparticles (NPs) and its potential application toward highly sensitive electrochemical detection of furazolidone (FZD) have been reported. UV–visible spectroscopy, X-ray diffraction, scanning electron microscopy, and Zeta sizer are systematically carried out to confirm the formation, size distribution, and composition of Ag@Fe 3 O 4 NPs. By computing the electrochemical characteristic parameters such as electrochemically active surface area (ECSA), electron-transfer resistance (R ct ), standard heterogeneous rate constant (k 0 ), adsorption capacity ( Γ ), and electron transfer rate constant (k s ), the Ag@Fe 3 O 4 -modified electrode possessed remarkably enhanced electrochemical sensing performance for FZD determination compared to the unmodified screen-printed electrode (SPE). This enhancement of electrochemical activity can be attributed to the fast electron transfer kinetics and great adsorption capacity that arise from the synergistic coupling between the good electrical conductivity of the core AgNPs and the porosity of the protective Fe 3 O 4 shell. Under optimum conditions, the Ag@Fe 3 O 4 -based electrochemical nanosensor exhibited not only high sensitivity toward FZD detection of 1.36 μ A μ M −1 cm −2 in the linear ranges from 0.5–15 μ M and 15–100 μ M, and low detection limit of 0.24 μ M but also long-term stability, repeatability, and anti-interference ability. The applicability of the proposed sensing platform in honey and milk samples was also investigated.