A Non-enzyme Amperometric Immunosensor for Rapid Determination of Human Immunodeficiency Virus p24 Based on Magnetism Controlled Carbon Nanotubes Modified Printed Electrode

A magnetism-controlled, disposable amperometric immunosensor was fabricated for the determination of human immunodeficiency virus p24 antigen. First, Fe3O4 (core)/Au (shell) nanoparticle [gold magnetic particle (GMP)]-coated multiwalled carbon nanotubes (MWCNT-GMP) were prepared. Then, monoclonal antibody (anti-p24) was immobilized on MWCNT-GMP to prepare MWCNT-GMP/anti-p24 composite magnetic particles. At last, MWCNT-GMP/anti-p24 was adsorbed on the surface of N,N'-bis-(2-hydroxy-methylene)-o-phenylenediamine copper (CuRb)-modified, screen-printed carbon electrodes through external magnetic field. Cyclic voltammetry and differential pulse voltammetry (DPV) were used to study the electrochemical properties of the modified electrode. The amount of p24 in the serum sample of patients with AIDS was determined by one-step immunoassay. When different concentrations of p24 were added into 25 μL of phosphate-buffered solution (pH 7.0) containing 1.0 μM H2O2, the percentage of DPV cathodic peak current decrease (CR, %) exhibited a linear relationship with the concentration of p24 in the range of 0.6-160 μg L−1. The detection limit was 0.32 μg L−1 (3σ). The immunosensor was used to determine p24 in serum samples of patients with AIDS, and the results were consistent with those of the traditional ELISA method. The proposed amperometric immunosensor was sensitive, rapid, magnetic field-controlled, and disposable; therefore, it could be used to determine even traces of p24 in the blood serums of patients with AIDS.