A Novel Electrochemiluminescence Immunosensor for the Analysis of HIV-1 p24 Antigen Based on P-RGO@Au@Ru-SiO2 Composite

Ru(bpy)3(2+)-doped silica (Ru-SiO2) nanoparticles and gold-nanoparticle-decorated graphene (P-RGO@Au) were combined to form a P-RGO@Au@Ru-SiO2 composite. The composite was used to develop a novel sandwich-type electrochemiluminescence immunosensor for the analysis of HIV-1 p24 antigen. The composite worked as carrier to immobilize target antibody and to build a sandwich-type electrochemiluminescence immunosensor through an interaction between antigen and antibody. Importantly, high ECL signal could be obtained due to the large amounts of Ru(bpy)3(2+) molecules per Ru-SiO2 nanoparticle. The P-RGO@Au composite with good conductivity and high surface area not only accelerated the electron transfer rate but also improved the loading of both ECL molecules and capture antibody, which could further increase the ECL response and result in high sensitivity. Taking advantage of both Ru-SiO2 nanoparticles and the P-RGO@Au composite, the proposed immunosensor exhibited a linear range from 1.0 × 10(-9) to 1.0 × 10(-5) mg mL(-1) with a detection limit of 1.0 × 10(-9) mg mL(-1) for HIV-1 p24 antigen. The proposed ECL immunosensor was used to analyze HIV-1 p24 antigen in human serum, and satisfactory recoveries were obtained, indicating that the proposed method is promising for practical applications in the clinical diagnosis of HIV infection.