Ultrasensitive sensing of diethylstilbestrol based on AuNPs/MWCNTs-CS composites coupling with sol-gel molecularly imprinted polymer as a recognition element of an electrochemical sensor

An ultrasensitive electrochemical sensor for determination of diethylstilbestrol (DES) was successfully constructed in this paper. Gold nanoparticles (AuNPs) and multi-walled carbon nanotubes-chitosan composite (MWCNTs-CS) were stepwise modified on glassy carbon electrode (GCE). And these two nanomaterials were used to increase the electrode surface area to enhance the electron transfer rate, and finally amplify the sensor signal. Moreover, sol-gel molecularly imprinted polymer was then electrodeposited on the electrode surface. The modified electrode was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The important parameters controlling the performance of the modified electrode were also optimized. Electrochemical measurements were performed via differential pulse voltammetry (DPV). And under optimal conditions, the sensor showed a detection range of 1.0 × 10−10-1.0 × 10−6 mg/mL with a detection limit of 24.3 fg/mL. At three concentration levels, the recovery rates for the detected DES in milk samples were 91.5%-106.7%. The sensor also had good reproducibility, stability and selectivity for DES detection.