Ultrasensitive electrochemiluminescence immunosensor based on Co-doped MoOx as co-reactant generator for the detection of amyloid β-protein

Abstract

Herein, a novel electrochemiluminescence (ECL) immunosensor was constructed to detect amyloid β-protein (Aβ) by using Co2+ doped MoOx (Co@MoOx) as both sensing substrate and coreactant generator, Au nanoclusters and isoluminol (Au NCs-ABEI) as secondary antibody label. Co@MoOx showed good electrolysis performance of aquatic oxygen, and the dissolved oxygen just acted as a coreactant of the ABEI emitter in this system. Au NCs was synthesized from reduced glutathione, which had ultrasmall size and good biocompatibility. Bioconjugate Au NCs-ABEI was constructed on Au NCs surface by cross-linking ABEI with amino group on ABEI surface. Through modifying Co@MoOx and Au NCs-ABEI on the electrode successively, the ECL signal intensity of immunosensor increased, which showed high sensitivity for the detection of Aβ, with the detection range from 1.00 fg·mL−1 to 500 pg·mL−1 and the detection limit as low as 0.330 fg·mL−1. This strategy will provide some reference for the early diagnosis and prevention of Alzheimer's disease (AD) and detection of other disease markers.