An Amperometric Immunosensor for IgG Based on Conducting Polymer and Carbon Nanotube-Linked Hydrazine Label

An amperometric immunosensor for IgG was developed by covalently immobilizing anti-IgG on multiwall carbon nanotube-embedded conducting polymer, poly-5,2' : 5 '', 2 ''-terthiophene-3'-carboxylic acid (MWCNT/pTTCA). The MWCNT/pTTCA modified electrode was characterized by SEM, EIS, and XPS. A hydrazine-labeled secondary antibody-MWCNT conjugate (Hyd-MWCNT-Ab(2)) was applied for detection. Hydrazine was used as a catalyst for the reduction of hydrogen peroxide, which was monitored at -0.3 V vs. Ag/AgCl. The calibration plots showed a linear range of 0.1-10 ng/mL with a detection limit of 0.084 +/- 0.004 ng/mL. The proposed immunosensor was evaluated for clinical applications in a rabbit serum sample.