Jiehua Lin

A sensitive dual immunoassay was proposed for the determination of carcinoembryonic antigen (CEA) and α-fetoprotein (AFP) based on signal amplification. Monoclonal antibodies immobilized on magnetic mesoporous silica particles (Fe3O4/SiO2) were prepared as the primary probe. Horseradish peroxidase (HRP) labeled antibodies co-coated with HRP on gold nanoparticles (AuNPs) were used as the secondary probe to achieve signal amplification. HRP tags were retained in the flow cells after a sandwich immunoassay. By controlling two switches on the two channels, chemiluminescent substrates were injected orderly man way, and then signals for CEA and AFP were sequentially detected by HRP-luminol-H2O2. Due to the increased amount of HRP on AuNPs and the increased amount of monoclonal antibodies on Fe3O4/SiO2, the signals were largely amplified. Under the optimal conditions, CEA and AFP could be detected in the linear ranges of 1.0 – 80 and 1.0 – 75 ng mL−1 with detection limits of 0.25 and 0.5 ng mL−1, respectively.