Electrochemiluminescence immunosensor for α-fetoprotein using Ru(bpy)32+-encapsulated liposome as labels

In this work, an electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of α-fetoprotein (AFP) was fabricated using Ru(bpy)32+-encapsulated liposome as the label and electrodeposited gold nanoparticles (GNPs) as the immobilizing support. Great signal amplification was achieved since liposome could encapsulate large amount of reporter molecules and GNPs could provide large active surface. Under optimized conditions, with sandwich type format, a linear range of AFP from 0.005 to 0.2 pg/mL and an extremely low detection limit of 0.001 pg/mL was obtained, much lower than that in previous reports. The proposed ECL immnuosensor showed high sensitivity, specificity, and good stability, which may open a new door to ultrasensitive detection of proteins in clinical analysis.

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► Fabrication of ECL immunosensor for AFP.
► Liposome labels contain many reporter molecules.
► GNPs provide large active surface.
► Linear range: 5–200 fg/mL, extremely low detection limit: 1 fg/mL.