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 x 10(-7) mg/mL and 4.5 x 10(-3) mg/mL (r = 0.996). The detection limit was 1.2 x 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. (C) 2012 Elsevier B.V. All rights reserved.