Magnetic electrode-based label-free electrochemical impedance spectroscopy immunosensor for sensitive detection of human malignant melanoma markers using gold nanoparticles functionalized magnetic graphene sheets as signal amplifier

Abstract

Cluster of differentiation 146 antigen (CD146) is a specific biomarker in the diagnosis of human malignant melanoma. In this work, a novel magnetic electrode-based label-free electrochemical impedance spectroscopy (EIS) immunosensor for quantitative detection of CD146 was established. Gold nanoparticles functionalized magnetic graphene sheets (Au@Fe₃O₄@GS) with good biocompatibility and electron transfer ability were used as transducing materials to achieve efficient conjugation of capture antibodies and signal amplification of the proposed immunosensor. For the facile and firm immobilization of magnetic transducing materials, the proposed immunosensor was fabricated on a magnetic glassy carbon electrode (MGCE). The effective immobilization of Au@Fe₃O₄@GS through the magnetic force of MGCE played a significant role in improving the stability and sensitivity of the proposed immunosensor. The EIS method was employed to record the impedance change of electrodes modified with different concentrations of CD146. The label-free EIS immunosensor exhibited a wide linear range from 5 pg mL⁻¹ to 500 ng mL⁻¹ with a low detection limit of 2.5 pg mL⁻¹ for CD146. The proposed immunosensor displayed an electrochemical performance with good reproducibility, selectivity and stability, which could provide potential applications in the clinical diagnosis of biomarkers.