A label-free and signal-on electrochemiluminescence strategy for sensitive amyloid-beta assay

Development of a simple, cost-effective and sensitive biosensing strategy is highly desirable to advance the applications in Alzheimer's disease diagnosis. In this paper, we present a simple, label-free and signal-on electrochemiluminescence (ECL) aptasensor for the detection of amyloid-beta (Aβ) peptide using luminol as ECL emitter and in-situ generated reactive oxygen species (ROS) as coreactant via catalytic reaction between Cu2+-Aβ and the dissolved O2 in the presence of ascorbic acid (AA). Aβ16, the binding site of Cu2+ in the monomeric full-length Aβ, was used as a model in present study. As a result, this signal-on ECL aptasensor has exhibited favorable analytical performance for Aβ16 monomer with a linear range of 1.0 × 10-13 mol/L-1.0 × 10-8 mol/L and a limit of detection of 3.5 × 10-14 mol/L (S/N=3). Furthermore, the proposed biosensor was also able to detect the full length Aβ40 not only in the phosphate buffer saline (PBS) solution but also in human serum. The presented biosensor represents a promising, simple, turn-on and label-free diagnostic tool for blood analysis.