Reagentless, Wash-Free Multiplexed Analysis of Plasma Biomarkers for Alzheimer’s Disease Diagnosis via an Antibody-Based Molecular Pendulum

Blood-based biomarkers have great potential for the early diagnosis of Alzheimer’s disease (AD); however, their implementation in primary healthcare screening remains largely limited owing to their reliance on sophisticated instruments and complex procedures. Furthermore, the complexity of the biological matrix poses a significant challenge to detection without washing and the use of reagents. Herein, we report a single-pot electrochemical sensing platform that enables rapid and ultrasensitive quantitative detection of AD biomarkers directly from untreated blood or plasma within 20 min of collection, without sample preparation, washing, or using additional reagents. This platform integrated high-affinity antibodies with an electric field-driven sensing mechanism based on a molecular pendulum. Upon the application of a potential, a negatively charged DNA scaffold moved directionally toward the electrode, enabling the real-time dynamic detection of surface-confined redox reporters and precise biomarker quantification. We validated the platform in 80 clinical plasma samples using Aβ42 and p-tau217 as representative biomarkers. We found that combined biomarker analysis outperformed single-analyte detection and achieved an area under the curve of 0.9475, with 82.5% sensitivity and 92.5% specificity. This work establishes a truly wash-free and reagentless electrochemical sensing strategy, showing great potential for early diagnosis of AD in community or home settings.