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

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 SiO2 (Au/SiO2) were prepared and used as a primary antibody. Horseradish peroxidase (HRP) and HRP-labeled secondary antibody (Ab2) co-immobilized into the mesoporous SiO2 nanoparticles (HRP–Ab2/SiO2) were used as the labeled immunological probe. Due to the high ratio surface areas and pore volumes of the mesoporous SiO2, not only the amount of AFP monoclonal antibody but also the amount of the modified HRP and Ab2 in HRP–Ab2/SiO2 were largely increased. Thus the chemiluminescent signal was amplified by using the system of luminol and H2O2 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 (3σ). The fabricated signal amplification strategy showed an excellent promise for sensitive detection of AFP and other tumor markers.

► The increased amount of monoclonal antibody in Au/SiO2 led to a wider linear range.
► Due to the increased HRP tags in HRP–Ab2/SiO2, signal amplification achieved.
► A simple dual amplification immunoassay achieved with flow injection analysis.