Poly-Adenine Assisted Signaling Displaced Probe Ratiometric Electrochemical Aptasensor for Accurate Detection of Alzheimer’s Disease Aβ Biomarkers

Alzheimer's disease (AD) is a widely prevalent neurodegenerative condition globally, arousing significant interest in the noninvasive early detection of the disease. The concentration of amyloid β (Aβ) biomarkers in the blood is closely linked to the progression of AD, emphasizing the importance of developing a precise method for detecting these biomarkers in blood samples for early diagnosis. In this study, we developed a ratiometric electrochemical aptamer-based (EAB) biosensor for accurate detection of Aβ₄₂ and Aβ₄₀. The ratiometric biosensor utilizes a gold nanoparticle (AuNPs) modified electrode through an electrochemical deposition assay and a self-assembled poly-A based U-shaped structure to achieve signal changes through competitive binding of target molecules. Importantly, using the calibration of the clipping reference probe, the proposed biosensor displayed accurate detection ability for Aβ₄₂ and Aβ₄₀, with detection limits of 59 and 21 pM, respectively. It also has great stability and anti-interference ability in complex biological samples. Furthermore, it demonstrated satisfactory performance in detecting the Aβ peptides in a 20% FBS sample, with recoveries ranging from 96.7% to 102.2% in serum samples, and relative standard deviations (RSD) ranging from 3.3% to 8.9%. Moreover, the proposed method is expected to directly quantify the Aβ₄₂/Aβ₄₀ ratio by introducing a suitable reference probe, providing a potential and effective tool for the early diagnosis of AD.