An ultrasensitive electrochemical immunosensor for detection of sex hormone binding globulin

Abstract

A novel electrochemical immunosensor was fabricated for detection of polycystic ovary syndrome (PCOS) by immobilizing horseradish peroxidase (HRP) labeled sex hormone binding globulin (SHBG) antibody (Ab) onto chitosan (CHIT), copper nanoparticles (CuNPs), iron nanoparticles (Fe3O4NPs) and graphene oxide nanoparticles (GrONPs) modified gold (Au) electrode. This HRP-SHBG Ab/CHIT/CuNPs/Fe3O4NPs/GrONPs modified Au electrode as working electrode, Ag/AgCl as standard electrode and Pt wire as auxiliary electrode were connected through potentiostat. The working electrode was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectra (EIS) during its construction. The immunosensor possessed a dynamic linear range (0.01–250 nM) with a low limit of detection (LOD) of 0.01 nM. The evaluation study of immunosensor displayed a good analytical recovery of 98.03%, when SHBG antigen concentration was added in the serum sample. In addition, within and between batch coefficients of variation for working electrode were 0.115% and 0.111%, respectively. The immunosensor exhibited a correlation coefficient of (R2 = 0.99), which was underlying in agreement with standard method. The immunosensor lost 10% of its initial activity after its regular use for 180 days, while being stored at 4 °C.