A quenching electrochemiluminescence immunosensor based on a novel Ag@Ce2Sn2O7 luminophore for the detection of neuron-specific enolase

A quenching electrochemiluminescence (ECL) immunosensor for neuron-specific enolase (NSE) detection was constructed by the resonance energy transfer between Ag@Ce2Sn2O7 (energy donor) and Ag@Cu2O (energy acceptor). The novel luminophore, Ag@Ce2Sn2O7, was synthesized by complexing Ce2Sn2O7 nanocubes with Ag concave-convex nanospheres. It exhibits a stronger ECL emission and a lower potential required for the emissions than pure Ce2Sn2O7. The Ag@Cu2O core-shell structure is composed of a dense Ag core inside and a loose Cu2O shell that provide a large specific surface area and the protection for the independence and integrity of the Ag core. The UV-Vis absorption of Ag@Cu2O overlaps the ECL emission of Ag@Ce2Sn2O7, and thus it can act as a quencher to effectively quench the ECL signal of Ag@Ce2Sn2O7. The great application potentials of the immunosensor in the NSE detection is demonstrated with the good linearity in the wide concentration range of 25 fg/mL - 100 ng/mL, and the low detection limit of 8.6 fg/mL. Our work has provided a reference for the immunosensor development of other biomarkers.