Amplified electrochemiluminescence detection of CEA based on magnetic Fe3O4@Au nanoparticles-assembled Ru@SiO2 nanocomposites combined with multiple cycling amplification strategy.

In this work, we designed a new strategy for ultrasensitive detection of CEA based on efficient electrochemiluminescence (ECL) quenching of Ru(bpy)32+-doped SiO2 nanocomposite by ferrocene using target recycling amplification technique. A large number of Ru@SiO2 ECL signal probe were firstly assembled on the novel magnetic core-shell Fe3O4@Au nanoparticles (NPs), then the ferrocene-labeled ECL quenching probe (Fc-probe) was linked to the magnetic NPs. Finally, numerous DNA1 sequences were produced by target CEA-triggered multiple recycling amplification and displaced the Fc-probe on the magnetic NPs, leading to significantly enhanced ECL signal for CEA detection. Because of the designed cascade signal amplification strategy, the newly developed method achieved a wide linear range of 10 fg/mL to 10 ng/mL with a low detection limit of  3.5 fg/mL. Furthermore, taking advantages of the magnetic Fe3O4@Au NPs for carring abundant signal probes, sensing target and ECL detection, the developed ECL strategy is convenient, rapid and displayed high sensitivity for CEA detection, which has great potential for analyzing the clinical samples in practical disease diagnosis applications.