Development of a functional impedimetric immunosensor for accurate detection of thy- roid-stimulating hormone

Abstract

Thyroid-stimulating hormone (TSH) that regulates the synthesis of thyroid gland hormones controlling all metabolism is one of the pituitary hormones. Determination of TSH is crucial for monitoring thyroid gland-related disorders and some metabolic diseases.In this study, a non-labeled immunosensor based on covalent immobilization of anti-TSH antibody by using the formation of self-assembled monolayers (SAM) of 4mercaptophenylacetic acid (4-MPA) and functionalization of carboxyl ends with 1ethyl-3-(3-dimetilaminopropil) carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) was fabricated for detection of TSH. Immobilization steps including the concentration of 4-2 MPA, the concentration of anti-TSH antibody and duration of anti-TSH antibody incubation were optimized by utilizing electrochemical impedance spectroscopy. Under optimal conditions, a sensitive, rapid and accurate determination of TSH at a concentration range between 0.7 -3.5 mIU/L was accomplished with a notable linearity and LOD value as 0.034 mIU/L as well as reproducibility and repeatability. Moreover, for comparison, linear range experiments were also carried out by using other electrochemical methods including Linear Sweep Voltammetry (LSV), Cyclic Voltammetry (CV) and capacitance spectroscopy (C). Finally, the constructed immunosensor was used for analyzing TSH levels spiked in the artificial serum samples.