Comparative analyses of plasma amyloid-β levels in heterogeneous and monomerized states by interdigitated microelectrode sensor system

Detection of amyloid-beta (A beta) aggregates contributes to the diagnosis of Alzheimer disease (AD). Plasma A beta is deemed a less invasive and more accessible hallmark of AD, as A beta can penetrate blood-brain barriers. However, correlations between biofluidic A beta concentrations and AD progression has been tenuous. Here, we introduce a diagnostic technique that compares the heterogeneous and the monomerized states of A beta in plasma. We used a small molecule, EPPS [4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid], to dissociate aggregated A beta into monomers to enhance quantification accuracy. Subsequently, A beta levels of EPPS-treated plasma were compared to those of untreated samples to minimize inter-and intraindividual variations. The interdigitated microelectrode sensor system was used to measure plasma A beta levels on a scale of 0.1 pg/ml. The implementation of this self-standard blood test resulted in substantial distinctions between patients with AD and individuals with normal cognition (NC), with selectivity and sensitivity over 90%.