Ultrasensitive\nProtein Aggregate Quantification Assays\nfor Neurodegenerative Diseases on the Simoa Platform

Nanoscale aggregates play a key role in the pathogenesis\nof neurodegenerative\ndisorders such as Alzheimer’s and Parkinson’s disease.\nHowever, quantifying these aggregates in complex biological samples,\nsuch as biofluids and postmortem brain tissue, has been challenging\ndue to their low concentration and small size, necessitating the development\nof methods with high sensitivity and specificity. Here, we have developed\nultrasensitive assays utilizing the Quanterix Simoa platform to detect\nα-synuclein, β-amyloid and tau aggregates, including those\nwith common posttranslational modifications such as truncation of\nα-synuclein and AT8 phosphorylation of tau aggregates. All assays\nhad a detection limit in the low pM range. As a part of this work,\nwe developed silica-nanoparticle calibrators, allowing for the quantification\nof all aggregates. These assays were validated for aggregate and target\nspecificity through denaturation and cross-reactivity experiments.\nWe then applied these assays to brain homogenate samples from Alzheimer’s\ndisease and control samples, demonstrating their applicability to\npostmortem tissue. Lastly, we explored the potential of these assays\nfor blood-based diagnostics by detecting aggregates in serum samples\nfrom early Alzheimer’s disease patients.