A Diagnostic Platform for Extracellular Vesicle-Derived Biomarkers: Towards Early Detection of Alzheimer’s Disease PROJECT SUMMARY. Alzheimer’s disease (AD) poses a growing burden on our society, with cases expected to reach 12.7 million by 2050. While research supports biomarkers for early detection, most Alzheimer’s patients are diagnosed after exhibiting clinical symptoms. At this stage, the advanced progression of senile plaques and neurofibrillary tangles pose significant challenges to effective interventions. Moreover, established biomarkers, such as amyloid beta-42/amyloid beta-40 and phosphorylated tau, are currently limited to analysis in cerebrospinal fluid, making their potential for routine screening nearly impossible. Thus, there is a critical need for novel, non-invasive approaches to rapidly screen for preclinical Alzheimer’s to facilitate the application of early interventions, such as physical, pharmaceutical, and cognitive therapies. Recent work has demonstrated the potential of circulating extracellular vesicles as a promising source of biomarkers to monitor and diagnose various diseases, including AD. However, accessible technologies to accurately detect AD-associated extracellular vesicles and their constituents are not currently in clinical practice. Moreover, concentrations in blood are present in the low pico- to femtomolar range, limiting conventional detection by ELISA and Western blot. This proposal aims to address these critical needs and focuses on developing a new platform to detect tau in neuron-derived extracellular vesicles (NDEVs). We hypothesize that ultrasensitive detection (< 5 pg/mL) of NDEV-tau can be achieved by optimizing our surface-enhanced Raman spectroscopy (SERS) nanotag technology using a rational design-of-experiment approach. If our hypothesis is correct, we expect this work to serve as the foundation for developing a point-of-care device that can be used for routine screening of pre-symptomatic AD. With this goal in mind, we will focus on the following specific aims: (1) Synthesize ‘SERS nanotags’ with a high affinity for NDEV-tau and identify the characteristics for effective binding; (2) Assess NDEV-tau sensitivity and specificity using the SERS platform in spiked human serum. Ultimately, we expect to establish the limit of detection and sample volumes needed for accurate tau detection. By engineering SERS-active substrates for ultrasensitive detection of NDEV-tau, we can then build upon this platform to enhance the multiplexing of several AD-associated biomarkers in complex biological samples. Our long-term goal is to develop SERS-based bioanalysis to drastically improve current standards in molecular detection for AD in both clinical and research settings.

A Diagnostic Platform for Extracellular Vesicle-Derived Biomarkers: Towards Early Detection of Alzheimer’s Disease IMPACT STATEMENT. This work can be expected to produce the foundations for a new assay to detect Alzheimer’s disease prior to the onset of clinical symptoms. A clinical tool to screen for Alzheimer’s disease could support early interventions to improve patient prognosis and decrease both the societal and economic costs associated with long-term care.