A label-free electrochemical aptasensor based on platinum@palladium nanoparticles decorated with hemin-reduced graphene oxide as a signal amplifier for glypican-3 determination

Abstract

Glypican-3 (GPC3) is a membrane-associated proteoglycan that is specifically upregulated in hepatocellular carcinoma (HCC) and has become one of the most promising biomarkers closely related to the occurrence and development of HCC. In this work, platinum@palladium nanoparticles decorated with hemin-reduced graphene oxide (H-rGO-Pt@Pd NPs) were used not only as a support for GPC3 aptamer (GPC3_Apt) immobilization, but also as a new redox nanoprobe in electrochemical analysis for the determination of GPC3. The electrochemical aptasensor involved a reaction cell with a three-electrode system, and the differential pulse voltammetry (DPV) technique was adopted. In the presence of GPC3, the formed GPC3_Apt–GPC3 complexes had stable structures and were cleaved from the electrode surface, leading to more electroactive H-rGO-Pt@Pd NPs repelling freely from the GPC3_Apt/H-rGO-Pt@Pd NPs and thus to the increase of the oxidation peak current of hemin in H-rGO-Pt@Pd NPs. Under optimal conditions and a working voltage of +700 mV (vs. Ag/AgCl), the label-free electrochemical GPC3 aptasensor showed superior performance with a wider concentration linear range (0.001–10.0 μg mL⁻¹), a lower limit of detection (LOD) (0.181 ng mL⁻¹, S/N = 3), a higher sensitivity (0.0446 μA μM⁻¹ cm⁻²) and good selectivity. Furthermore, the fabricated aptasensor was applied to GPC3 determination in human serum samples with satisfactory recoveries of 94.3%–119% and RSDs of 0.15%–5.78%. The current work provides a flexible approach for the rapid and sensitive analysis of GPC3 and has a broad application prospect in the diagnosis of HCC.