High-performance electrochemical aptasensor for detection of glypican-3 based on nitrogen-doped reduced graphene oxide-ferrocene-polyaniline nanocomposites

Hepatocellular carcinoma (HCC) is a high-mortality malignancy that urgently requires sensitive early-stage biomarkers. Glypican-3 (GPC3), a highly specific protein biomarker for HCC, calls for efficient detection strategies. Herein, we developed a label-free electrochemical aptasensor based on nitrogen-doped reduced graphene oxide-ferrocene-polyaniline (NRGO-Fc-PANI) nanocomposites and GPC3 aptamer for GPC3 detection. The NRGO-Fc-PANI combined the large high surface area and conductivity of NRGO, high electrical conductivity and stability of PANI, and the good redox properties of Fc, which functed as in situ electrochemical redox signal indicator to monitor the electrochemical changes. Upon target binding, the formation of GPC3-aptamer complex fell off from the electrode, exposing the conductive NRGO-Fc-PANI layer and enhancing the differential pulse voltammetry (DPV) response. The aptasensor exhibited a linear detection range of 10.0–100.0 ng·mL⁻¹ (R² = 0.996) and a low limit of detection (LOD) of 2.88 ng·mL⁻¹. It demonstrated excellent selectivity toward interfering proteins, retained 70.8 % of its initial signal after 11 days of storage, and attained a recovery range of 97.0–109.5 % in human serum samples. By eliminating the need for enzymatic or fluorescent reporters, the aptasensor reduced reagent costs and operational complexity, presenting a clinically promising tool for the early diagnosis of HCC.