科研之友
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摘要
A novel nonenzymatic electrochemical immunosensor was fabricated for quantitative detection of alpha-fetoprotein (AFP). The immunosensor was constructed by modifying gold electrode with electrochemical reduction of graphene oxide-carboxyl multi-walled carbon nanotube composites (ERGO-CMWCNTs) and electrodeposition of gold nanoparticles (AuNPs) for effective immobilization of primary antibody (Ab(1)). Ferroferric oxide-manganese dioxide-reduced graphene oxide nanocomposites (Fe3O4@MnO2-rGO) were designed as labels for signal amplification. On one hand, the excellent electroconductivity and outstanding electron transfer capability of ERGO-CMWCNTs/AuNPs improved the sensitivity of the immunosensor. On the other hand, introduction of rGO could not only increase the specific surface area for immobilization of secondary antibody (Ab(2)) but also build a synergetic effect to reinforce the electrocatalytic properties of catalysts. Fe3O4@MnO2-rGO nanocomposites were characterized by scanning electron microscope, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Using AFP as a model analyte, the proposed sandwich-type electrochemical immunosensor exhibited a wide linear range of 0.01-50 ng . mL(-1) with a low detection limit of 5.8 pg . mL(-1). Moreover, the Fe3O4@ MnO2-rGO-based peroxidase mimetic system displayed an excellent analytical performance with low cost, satisfactory reproducibility and high selectivity, which could be further extended for detecting other disease-related biomarkers.
