One-step enzyme-free dual electrochemical immunosensor for histidine-rich protein 2 determination

Abstract

In the present work, we describe a novel one-step enzyme-free dual electrochemical immunosensor for the determination of histidine-rich protein 2 (Ag-<i>Pf</i>HRP2), a specific malaria biomarker. A gold electrode (GE) was functionalized with the <i>Pf</i>HRP2 antibody (Ab-<i>Pf</i>HRP2) using dihexadecyl phosphate (DHP) polymer as an immobilization platform. The Ab-<i>Pf</i>HRP2/DHP/GE sensor was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The developed immunosensor was employed for indirect Ag-<i>Pf</i>HRP2 determination by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The linear range was 10-400 ng mL^-1 and 10-500 ng mL^-1 for EIS and DPV, while the limit of detection was 3.3 ng mL^-1 and 2.8 ng mL^-1, respectively. The electrochemical immunosensor was successfully applied for Ag-<i>Pf</i>HRP2 determination in human serum samples. Its performance was compared with an ELISA test, and good correspondence was achieved. The coefficients of intra- and inter-assay variations were less than 5%. The electrochemical immunosensor is a useful and straightforward tool for <i>in situ</i> malaria biomarker determination.