Reagentless amperometric immunosensor for α-1-fetoprotein based on assembly of nano-Au@SiO2 composite

Abstract

A novel immunosensor for the direct amperometric determination of α-1-fetoprotein (AFP) was constructed by immobilization of PDDA/nano-Au@SiO₂ onto a Prussian blue modified gold electrode surface, followed by adsorption of α-1-fetoprotein antibody onto nano-Au@SiO₂ composite particles with large specific areas and good biocompatibility. Finally, BSA was employed to block the possible remaining active sites of the nano-Au@SiO₂ layer to avoid non-specific adsorption. The modification procedure was electrochemically monitored by cyclic voltammetry. The performance and influencing factors of the resulting immunosensor were studied in detail. Under the optimized conditions, there is a linear relation between response current and the logarithm of the concentrations of AFP in the concentration range of 0.05–200 ng mL⁻¹ with a detection limit of 0.02 ng mL⁻¹ (S/N = 3).