Background-Free Surface-Enhanced Raman Scattering Aptasensor for Ultrasensitive Aβ₄₀ Detection.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Early detection of Alzheimer's disease (AD) is crucial for effective management.
• Amyloid-beta 40 (Aβ40) in blood is a key biomarker for AD screening.
• Existing detection methods face challenges with sensitivity and specificity.

Purpose of the Study:

• To develop a novel, ultrasensitive, and background-free SERS platform for Aβ40 detection.
• To combine dual-aptamer recognition with magnetic-induced enrichment for enhanced performance.
• To establish a robust tool for early AD diagnosis and clinical molecular diagnostics.

Main Methods:

• Designed Au@Ag-4-ethynylaniline@Au nanoparticles (Au@Ag-4-EA@Au NPs) as SERS probes.
• Functionalized NPs with 4-EA to utilize the Raman silent region, minimizing interference.
• Developed a sandwich assay using Aβ40-specific aptamers on magnetic beads and NPs for capture and detection.
• Employed magnetic-induced enrichment for signal amplification and "hot spot" generation.

Main Results:

• Achieved a remarkable limit of detection of 25 fM (S/N = 3) for Aβ40.
• Demonstrated a wide linear detection range from 10⁻¹ to 10⁴ pM.
• The SERS platform showed high specificity and sensitivity due to dual-aptamer recognition and magnetic enrichment.
• Minimized biological interference and spectral overlapping by using the Raman silent region.

Conclusions:

• The developed SERS platform offers a powerful and sensitive tool for early Alzheimer's disease screening.
• Dual-aptamer recognition and magnetic enrichment significantly enhance Aβ40 detection.
• The background-free SERS approach shows broad potential for clinical molecular diagnostics.