Chemiluminescence immunoassay based on dual signal amplification strategy of Au/mesoporous silica and multienzyme functionalized mesoporous silica

Abstract

► The increased amount of monoclonal antibody in Au/SiO 2 led to a wider linear range. ► Due to the increased HRP tags in HRP–Ab 2 /SiO 2 , signal amplification achieved. ► A simple dual amplification immunoassay achieved with flow injection analysis. A chemiluminescent dual signal amplification strategy for the determination of α-fetoprotein (AFP) was proposed based on a sandwich immunoassay format. Monoclonal antibody of AFP immobilized on the gold nanoparticles doped mesoporous SiO 2 (Au/SiO 2 ) were prepared and used as a primary antibody. Horseradish peroxidase (HRP) and HRP-labeled secondary antibody (Ab 2 ) co-immobilized into the mesoporous SiO 2 nanoparticles (HRP–Ab 2 /SiO 2 ) were used as the labeled immunological probe. Due to the high ratio surface areas and pore volumes of the mesoporous SiO 2 , not only the amount of AFP monoclonal antibody but also the amount of the modified HRP and Ab 2 in HRP–Ab 2 /SiO 2 were largely increased. Thus the chemiluminescent signal was amplified by using the system of luminol and H 2 O 2 under the catalysis of HRP. Under the optimal conditions, two linear ranges for AFP were obtained from 0.01 to 0.5 ng mL −1 and 0.5 to 100 ng mL −1 with a detection limit of 0.005 ng mL −1 (3 σ ). The fabricated signal amplification strategy showed an excellent promise for sensitive detection of AFP and other tumor markers.