Highly sensitive electrochemical aptasensor for Glypican-3 based on reduced graphene oxide-hemin nanocomposites...

Glypican-3 (GPC3) is a highly specific tumor marker for hepatocellular carcinoma (HCC), and plays an important role in reflecting the existence, therapeutic evaluation, monitoring and prognosis of HCC. Herein, an electrochemical aptasensor was designed for GPC3 detection with the reduced graphene oxide-hemin nanocomposites (RGO-Hemin) modified on the screen-printed electrode surface as the sensing platform and GPC3 aptamer as recognize molecule. In the existence of GPC3, the aptamer can specifically bind with the target GPC3 and form GPC3-aptamer conjugations on the sensing surface, which would increase the resistance of the electron transfer on the electrode and make the decrease of electrochemical signals of Hemin in RGO-Hemin nanocomposites. The electrochemical current change was recorded by differential pulse voltammetry (DPV). Scanning electron microscopy (SEM), Raman microscope (RM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the GPC3 electrochemical aptasensor. Under the optimum conditions, the current response of the electrochemical aptasensor is linearly correlated with the concentration of GPC3 (0.001-10.0 μg/mL) with the detection limit of 2.86 ng/mL (S/N = 3) and the sensitivity of 0.134 μA/μM/cm². In addition, the aptasensor was applied to the determination of GPC3 in spiked human plasma and the recoveries fluctuated from 102.68% to 117.29%. All these results show that the aptasensor has good specificity, sensitivity, stability and reproducibility for GPC3 detection.