A novel electrochemical immunosensor based on poly(m-aminophenol) modified expanded graphite electrode

An electrochemical immunosensing method was developed based on poly(m-aminophenol) (PmAP) immobilized goat anti-human IgG (anti-IgG). Glutaraldehyde (GA) was used as a coupling reagent, its two aldehyde groups reacted with the amino groups of PmAP electrodeposited on the expanded graphite (EG) surfaces and the amino groups of anti-IgG, respectively. In this immunoassay, human IgG was fixed as the target antigen, horseradish peroxidase (HRP)-conjugated goat anti-human IgG (HRP-anti-IgG) as the probing antibody and poly(methylene blue) (PMB) as the electron mediator. The oxidation peak current of PMBH (the reduction state of PMB) was proportional to the concentration of IgG in the range from 5 to 60 μg mL−1, and the detection limit was 0.19 μg mL−1 (signal-to-noise ratio of 3). The proposed system reduced complexity and costs which are considered as the most wanted features in the point-of-care diagnostics application of clinical screening of multiple diseases.