Ultrasensitive Electrochemiluminescence Immunoassay for Protein Specific Detection Based on Dendrimer-Encapsulated Gold Nanoparticles Labels

Abstract

A sensitivity-enhanced electro chemiluminescence immunoassay (ECLIA) was fabricated by covalently immobilizing a monoclonal prostate specific antigen (PSA) antibody (anti-PSA, Ab2) and a luminophore (luminol) on dendrimer-encapsulated gold nanoparticles (Den/AuNPs) as electrochemiluminescence labels. The primary antibody was immobilized on Fe3O4@SiO2 NP support, and the antibody-loaded Fe3O4@SiO2 NP was placed onto an indium tin oxide working electrode in a home made electrochemiluminescence (ECL) cell. PSA and Ab2/Luminol/Den/AuNP was successively injected into the cell, and conjugated to form a sandwich-type immunocomplex. Under optimized experimental conditions, the proposed ECLIA provided a linear response range from 0.001 to 100.0 ng/mL with a low detection limit of 0.3 pg/mL. The PSA assay results in clinical serum samples were in good agreement with the commercially available electro chemiluminescence assay. The ECL immunosensor has the advantages of high sensitivity, specificity and stability and may be a promising technique for tumor marker detection.