Biofunctionalized dendritic polyaniline nanofibers for sensitive electrochemical immunoassay of biomarkers

Abstract

Multi-armed dendritic polyaniline nanofibers (MPANFs) were first synthesized and functionalized with horseradish peroxidase (HRP) and carcinoembryonic antibody (anti-CEA) for highly efficient electrochemical immunoassay of carcinoembryonic antigen (CEA, as a model analyte here) in this work. Transmission electron microscope (TEM) and scanning electron microscope (SEM) techniques were employed to characterize the synthesized MPANFs. By using anti-CEA-conjugated core–shell gold–Fe₃O₄ nanocomposites (GoldMag) as immunosensing probes and biofunctionalized MPANFs as molecular tags, a new sandwich-type homogeneous immunoassay strategy was developed for the determination of CEA by coupling with a home-made flow-through magneto-controlled microfluidic device. Under optimal conditions, the electrochemical immunoassay exhibited a wide dynamic range of four orders of magnitude from 1.0 pg mL⁻¹ to 50 ng mL⁻¹ with a low detection limit of 0.1 pg mL⁻¹ CEA at 3σ. Intra- and inter-assay coefficients of variation were below 10%. The assayed results for clinical serum specimens with the electrochemical immunoassay were received in good accordance with the results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.