Electrochemical immunosensor for the detection of anti-thyroid peroxidase antibody by gold nanoparticles and ionic liquid-modified carbon paste electrode

In this work, a sandwich-type electrochemical immunosensor was designed based on the modification of the carbon paste electrode consisting of ionic liquid and graphite for the effective detection of anti-thyroid peroxidase antibody (anti-TPO). The ionic liquid carbon paste electrode surface was electrodeposited by biocompatible and electrically conductive gold nanoparticles (NPs) as a sensing platform. The human recombinant TPO (Ab1), anti-TPO antibody (Ag) and horseradish peroxidase (HRP)-anchored anti-TPO secondary antibody (HRP-Ab2) were successively immobilized on the Au NPs/CILE surface to construct the immunosensor. The immunosensor response signal was recorded by differential pulse voltammetry based on HRP catalysis in the reaction of H2O2 with O-aminophenol. An elevation in anti-TPO antibody concentration increased the current responses, probably due to the immobilization of a high amount of HRP-Ab2 on the electrodes for higher anti-TPO antibody concentration. The immunosensor, under the optimized circumstances, presented a low limit of detection (LOD) (6.0 ng mL−1) towards the anti-TPO antibody determination with a broad linear range (0.02–60.0 μg mL−1). Moreover, the prepared immunosensor showed good reproducibility and good stability.