Dynamic evaluation of cell-secreted interferon gamma in response to drug stimulation via a sensitive electro-chemiluminescence immunosensor based on a glassy carbon electrode modified with graphene oxide, polyaniline nanofibers, magnetic beads, and gold nanoparticles

A sensitive electrochemiluminescent (ECL) immunosensor was developed for real-time and dynamic evaluation of the concentration of interferon gamma (IFN-γ) that is secreted by peripheral blood mononuclear cells. IFN-γ is a diagnostic marker for latent infections with Mycobacterium tuberculosis (MTB), and its levels vary in response to drugs stimulation. The ECL immunosensor was fabricated by attaching gold nanoparticle-coated magnetic beads (AuNP@MB) on a nanofiber prepared from graphene oxide and polyaniline (GO-PANI-NF). The sensor possesses a three-dimensional structure nanocomposite that is beneficial for immobilization of primary antibodies (Ab1), and this enhances the intensity of ECL. The assay is based on a sandwich-type immunoreaction in which secondary antibodies (Ab2) labeled with CdS quantum dots (QDs) are used to generate ECL. The assay has a wide linear range (0.1–500 pg⋅mL−1) and a low detection limit (30 fg∙mL−1). The method was applied to real-time and dynamic determination of IFN-γ in supernatants of peripheral blood mononuclear cells in response to stimulation by chlorogenic acid. Conceivably, it may be used for monitoring the dynamic variation of biomarkers in cells supernatants in response to drug stimulation and to diagnose other infectious diseases.