Detection of HIV-1 p24 antigen using streptavidin–biotin and gold nanoparticles based immunoassay by inductively coupled plasma mass spectrometry

Abstract

A sensitive assay for detection of HIV-1 p24 antigen by inductively coupled plasma mass spectrometry (ICP-MS) was developed using a biotin–streptavidin (BA) system and gold nanoparticles (Au NPs) based immunoassay. In this immunoassay, the p24 antigen was firstly captured by an immobilized anti-HIV-1 p24 monoclonal antibody. After immunoreactions with the biotinylated anti-p24 polyclonal antibody and Au NPs-labeled streptavidin, diluted HNO₃ (5%, v/v) was used to dissociate Au NPs, which were then introduced to the ICP-MS for measurements. Under the optimized conditions, the calibration graph for the p24 antigen was linear in the range of 7.5–75 pg mL⁻¹ with a detection limit of 1.49 pg mL⁻¹ (3σ, n = 5). The relative standard deviation (RSD) for three replicate measurements of 37.5 pg mL⁻¹ of the p24 antigen was 3.7%. Other proteins, such as human IgG, human HSA, human CEA and human AFP, did not obviously interfere with the assay for p24 antigen. This method was also applied to measure p24 concentrations in artificially positive human serum samples. Compared with the biotin–streptavidin enzyme-linked immunosorbent assay (BA-ELISA) method for p24 antigen detection, the ICP-MS linked immunoassay process deals with Au NPs – tagged instead of enzyme-conjugated antibodies, making it free of toxic enzyme substrate reagents. In addition, it also simplifies the experimental process and saves the experimental time, since the color rendering steps are omitted. The proposed approach provides a sensitive method for HIV-1 p24 antigen determination.