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

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 (FeO) 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 FeO 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 concentration ranges of both AFP and GPC-3; and the respective detection limits are 50 and 70 pg mL. 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 (FeO) 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.