A novel electrochemical aptasensor based on gold electrode decorated Ag@Au core-shell nanoparticles for sulfamethazine determination

In this paper, an electrochemical aptasensor based on gold electrode (AuE)-modified Ag@Au core-shell nanoparticles was prepared. The surface of AuE was modified with Ag@Au core-shell nanoparticles to elevate APT binding sites and accelerate electron transfer properties between the electrode and ferrocene (Fc). When SM 2 existed, the aptamer conformation would change and the response current intensity would increase because the Fc was pulled closer to the electrode surface. Subsequently, through a series of conditional optimization analysis, the optimal values of volume of Ag@Au core-shell, APT concentration, APT incubation time, and SM 2 incubation time were 9 μL, 0.2 μmol/L, 75 min, and 40 min, respectively. Under optimum conditions, the results of differential pulse voltammetry experiments showed that the linear relationship was good in the range of 0.1~50 ng/mL, Δ I ′ (μA) = 1.145 C (ng/mL) + 54.666, R 2  = 0.964, with a detection limit of 0.033 ng/mL. The spiked recovery for SM 2 in the pork samples was 92.6~101.0% and the relative standard deviation (RSD) was 2.7~4.1%, which indicated that the proposed aptasensor exhibited desirable performance in actual sample analysis. An electrochemical aptasensor based on gold electrode-modified Ag@Au core-shell nanoparticles was prepared. The detection principle was on the basis of the change of current signal of DPV in Tris-HCl buffer solution before and after incubation of SM 2 . After the formation of APT-SM 2 complex, the ferrocene modified on the aptamer was pulled closer to the electrode surface and sped up the electron transfer rate.