Simultaneous voltammetric immunodetection of alpha-fetoprotein and glypican-3 using a glassy carbon electrode modified with magnetite-conjugated dendrimers

Abstract

The authors describe an electrochemical immunoassay for simultaneous determination of alpha-fetoprotein (AFP) and glypican-3 (GPC-3) which are important biomarkers for early detection of hepatocellular carcinoma (HCC). Magnetite (Fe₃O₄) nanoparticles (NPs) were decorated with hyperbranched amino functionalized dendrimers. The modified NPs were coupled to the antibodies against AFP and GPC-3. The electrochemical behaviour of the Fe₃O₄ NPs and dendrimer-modified NPs were studied. A glassy carbon electrode was then modified with the NP-conjugated antibodies and biomolecular interactions were studied by using cyclic voltammetry and electrochemical impedance spectroscopy. Dual differential pulse voltammetric sensing was performed by utilizing the redox probes; Prussian blue for AFP and toluidine blue for GPC-3. The biomarkers can be detected best at voltages of 0.25 mV and - 0.54 mV (vs Ag/AgCl) for AFP and GPC-3, respectively. The low working potentials makes the method more selective over other electroactive species present in real human serum samples. Response is linear in 0.02 to 10 ng mL^-1 concentration ranges of both AFP and GPC-3; and the respective detection limits are 50 and 70 pg mL^-1. The method was validated by analysing spiked human serum samples. In our perception, the method is of great clinical significance as combination of GPC-3 and AFP increases the sensitivity of detection of HCC. Graphical abstract Schematic presentation of polyamidoamine (PAMAM) dendrimers modified magnetite (Fe₃O₄) nanoparticles as electrochemical sensing platform using redox dyes Prussian blue and toluidine blue for simultaneous detection of alpha-fetoprotein (AFP) and glypican-3 (GPC-3), respectively by differential pulse voltammetry.

Keywords: AFP; Biosensor; Cyclic voltammetry; Differential pulse voltammetry; Electrochemical impedance spectroscopy; Fe3O4 nanoparticles; GPC-3; Hepatocellular carcinoma; PAMAM dendrimer; Simultaneous detection.