Label-free electrochemical aptasensor based on reduced graphene oxide–hemin–chitosan nanocomposite for the determination of glypican-3

Glypican-3 (GPC3) is a potential hepatocellular carcinoma (HCC) serum marker with good sensitivity and specificity. Herein, a label-free electrochemical aptasensor for the detection of GPC3 was developed using a reduced graphene oxide–hemin–chitosan (RGO–H–CS) nanocomposite-modified screen-printed electrode (SPE) as a biosensing platform and GPC3 aptamer as the recognition element. When GPC3 was present, the aptamer could specifically bind with the target GPC3 by specific recognition reaction and form GPC3–aptamer conjugations on the sensing surface, which could alter the electrochemical redox signal of hemin (Fe(III)/hemin(Fe(II))) in the RGO–H–CS nanocomposite recorded by differential pulse voltammetry (DPV). The electrochemical GPC3 aptasensor was characterized via scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, currents originating from the oxidation of hemin had a linear relationship with the concentration of GPC3 in the range of 0.01 µg mL−1 to 10.0 µg mL−1 with a detection limit of 7.9 ng mL−1 (S/N = 3). The developed aptasensor was applied to detect the GPC3 level in the human serum samples with the recovery rate of 101.04–104.9%. Moreover, the label-free aptasensor exhibited considerable anti-interfering ability, acceptable stability and good reproducibility. Therefore, this study provides a reliable and objective analysis method to achieve high screening for the early diagnosis of HCC.