Development of a high-sensitivity immunoassay for amyloid-beta 1-42 using a silicon microarray platform

Area of Science:

• Biomarker Detection
• Assay Development
• Neurodegenerative Disease Research

Background:

• Alzheimer's disease (AD) diagnosis relies on detecting biomarkers like amyloid-beta 1-42 (Aβ42).
• Current detection methods may lack the sensitivity or throughput for early, widespread screening.
• Microarray platforms offer potential for sensitive, high-throughput biomarker detection.

Purpose of the Study:

• To develop a highly sensitive immunoassay for Aβ42 detection.
• To utilize a silicon/silicon oxide (Si/SiO2) microarray platform for enhanced sensitivity.
• To establish a method for early detection of preclinical Alzheimer's disease.

Main Methods:

• A silicon/silicon oxide (Si/SiO2) microarray platform was functionalized with a ter-copolymer (copoly(DMA-NAS-MAPS)).
• Label-free detection was performed using the Interferometric Reflectance Imaging Sensor (IRIS) for mass changes.
• Amyloid-beta 1-42 (Aβ42) aggregation was analyzed, and optimal antibody pairs were selected.

Main Results:

• The Si/SiO2 substrate enhanced signal intensity through constructive interference.
• Optimized incubation conditions yielded an unprecedented Aβ42 detection sensitivity of 73 pg/mL in artificial cerebrospinal fluid (CSF).
• The platform demonstrated suitability for multiplexed, high-throughput detection.

Conclusions:

• The developed immunoassay demonstrates high sensitivity for Aβ42 detection on a Si/SiO2 microarray.
• This platform is suitable for identifying individuals with preclinical AD.
• The assay's sensitivity and potential for adaptation to other biological fluids suggest a future non-invasive diagnostic tool for AD screening.