Aptamer Binding of Beta Amyloid for Early Detection of Alzheimer's Disease

Alzheimer’s Disease (AD) is projected to be a major medical burden by 2050 and early detection will hopefully reduce this burden through prevention and, yet to be discovered, treatment measures. The leading candidates for the neurotoxic species causing AD are beta amyloid 1-42 (Aβ_1-42) oligomers.  Detection in the cerebrospinal fluid of the variation in concentration of these structures and those of the protein tau could potentially be used for the diagnosis of AD.  Here, we develop an affinity biosensor for early detection of AD based on specific RNA aptamer-Aβ_1-42 binding interaction. Aptamers were chemically immobilized and oriented onto a gold-coated crystal for measurement in a Quartz Crystal Microbalance with Dissipation (QCM-D).  Both mass uptake (frequency change, Δf) and aptamer film rigidity (dissipation change, ΔD) were measured as a function of time to monitor aptamer immobilization and Aβ_1-42 binding.  Sensitivity, selectivity and robustness of the Aβ_1-42 oligomer sensor will be presented.