A Proof-of-Concept Study Aiming for the Integration of an Optical Biosensor in Advanced Microfluidic Devices for Alzheimer’s Disease Studies

Alzheimer’s disease (AD), a progressive neurodegenerative disorder, is marked by the abnormal production of amyloid-beta (Aβ) fibrils, a key biomarker for diagnosis and illness monitoring. Advanced microfluidic devices, such as brain-on-a-chip (BoC), are innovative preclinical tools with the potential to revolutionize AD early diagnosis and treatment. However, existing BoCs face limitations, including challenges in biosensing integration, limited sensitivity, and automation. In this study, we demonstrate the feasibility of integrating fluorescence-based detection of Aβ fibrils within microfluidic platforms, improving efficiency and precision in biomarker analysis, while also reducing sample volume requirements, with potential application in BoC. The fluorescent probe CRANAD-2, known for its in vivo specificity and strong fluorescence response to Aβ fibrils, was first characterized in a macroscale system to establish baseline performance. These results were used to guide subsequence microfluidic experiments, reducing sample volume while maintaining analytical reliability. The study revealed consistent fluorescence responses and a strong linear relationship between Aβ concentration and fluorescence intensity in both setups. This proof-of-concept study shows, for the first time, the potential of integrating optical biosensing into microfluidic devices for Aβ detection, offering a new technological tool for advancing AD studies.