Electrochemiluminescence resonance energy transfer system between GNRs and Ru(bpy)32+: Application in magnetic aptasensor for β-amyloid

Electrochemiluminescent (ECL) assay has gradually drawn increasing interest in the biomedical analysis. This paper proposed a new methodology for ultrasensitive and facile detection of Alzheimer's disease marker β-amyloid (Aβ) by fabricating a sandwich-type ECL sensing platform. Herein, electrochemiluminescence resonance energy transfer (ECL-RET) was employed to determine Aβ concentration, which can be attributed to the quenching effect from RET between Ru(bpy)32+ and gold nanorods (GNRs) acting as ECL-RET electron donor and acceptor, respectively. In this protocol, mesoporous carbon nanospheres were adopted to immobilize ECL reactant Ru(bpy)32+ and antibody via nafion to acquire the RET donor nanocomposites (MOCs/nafion/Ru(bpy)32+/antibody), which were tightly interconnected with epoxy group functionalized Fe3O4 nanoparticles. It is of vital importance that GNRs with exquisite rod shape were synthesized and exhibited a typical absorption peak at 650 nm to quench ECL signal of Ru(bpy)32+ effectively. In addition, the ECL emission decreased linearly with the logarithm of Aβ concentration in a wide linear range from 1.0 × 10−5 to 100 ng/mL with a detection limit of 4.2 × 10−6 ng/mL. Furthermore, distinctive and desirable properties were verified to declare the promise for being applicable to analyze the Aβ content in real Alzheimer's cerebrospinal fluid samples with satisfactory results.