Quantitative assessment of AD markers using naked eyes: point-of-care testing with paper-based lateral flow...

Aβ₄₂ is one of the most extensively studied blood and Cerebrospinal fluid (CSF) biomarkers for the diagnosis of symptomatic and prodromal Alzheimer's disease (AD). Because of the heterogeneity and transient nature of Aβ₄₂ oligomers (Aβ₄₂Os), the development of technologies for dynamically detecting changes in the blood or CSF levels of Aβ₄₂ monomers (Aβ₄₂Ms) and Aβ₄₂Os is essential for the accurate diagnosis of AD. The currently commonly used Aβ₄₂ ELISA test kits usually mis-detected the elevated Aβ₄₂Os, leading to incomplete analysis and underestimation of soluble Aβ₄₂, resulting in a comprised performance in AD diagnosis. Herein, we developed a dual-target lateral flow immunoassay (dLFI) using anti-Aβ₄₂ monoclonal antibodies 1F12 and 2C6 for the rapid and point-of-care detection of Aβ₄₂Ms and Aβ₄₂Os in blood samples within 30 min for AD diagnosis. By naked eye observation, the visual detection limit of Aβ₄₂Ms or/and Aβ₄₂Os in dLFI was 154 pg/mL. The test results for dLFI were similar to those observed in the enzyme-linked immunosorbent assay (ELISA). Therefore, this paper-based dLFI provides a practical and rapid method for the on-site detection of two biomarkers in blood or CSF samples without the need for additional expertise or equipment.