Analytical Sciences

A New Dual Immunoassay for Tumor Markers Based on Chemiluminescence Signal Amplification by Magnetic Mesoporous Silica and Enzyme Modified Gold Nanoparticles

Jiehua LIN, Pengfei CHU, and Zhijing WEI

Key Laboratory of Eco-chemical Engineering, Ministry of Education, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China

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.

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