Electrochemical immunosensor based on mesoporous nanocomposites and HRP-functionalized nanoparticles bioconjugates for sensitivity enhanced detection of diethylstilbestrol

An ultrasensitive electrochemical immunosensor based on mesoporous silica–gold nanoparticles–multiwall carbon nanotubes (MSN–GNPs–MWCNTs) nanocomposites and horseradish peroxidase–antibody–Prussian blue–multiwall carbon nanotubes (HRP–Ab–GNPs–PB–MWCNTs) bioconjugates was developed for the detection of diethylstilbestrol (DES). MSN–GNPs–MWCNTs nanocomposites as immobilization matrix were used to enhance the electroactivity and stability of the electrode. HRP–Ab–GNPs–PB–MWCNTs bioconjugates as label were used to improve catalytic activity for hydrogen reduction of the electrode. Meanwhile, HRP–Ab–GNPs–PB–MWCNTs were used as the second signal amplification strategy for the detection of DES in the sandwich immunoreaction. Under the optimized conditions, a calibration plot for DES was obtained with a linear range between 3.3 × 10−7 mg/mL and 4.5 × 10−3 mg/mL (r = 0.996). The detection limit was 1.2 × 10−7 mg/mL (S/N = 3). The proposed electrochemical immunosensor has excellent selectivity, good reproducibility and long-term stability. The total time taken for the assay was 7 min. The electrochemical immunosensor was examined in real samples for the analysis of DES. A good recovery in the range of 92–107% was obtained in milk and pork samples.