Detection of Amyloid-beta Fibrils Using Track-Etched Nanopores: Effect of Geometry and Crowding

Several neurodegenerative diseases have been linked to proteins or peptides that are prone to aggregate in different brain regions. Aggregation of amyloid-beta (A beta) peptides is recognized as the main cause of Alzheimer's disease (AD) progression, leading to the formation of toxic A beta oligomers and amyloid fibrils. The molecular mechanism of A beta aggregation is complex and still not fully understood. Nanopore technology provides a new way to obtain kinetic and morphological aspects of A beta aggregation at a single-molecule scale without labeling by detecting the electrochemical signal of the peptides when they pass through the hole. Here, we investigate the influence of nanoscale geometry (conical and bulletlike shape) of a track-etched nanopore pore and the effect of molecular crowding (polyethylene glycol-functionalized pores) on A beta fibril sensing and analysis. Various A beta fibril samples that differed by their length were produced by sonication of fibrils obtained in the presence of epigallocatechin gallate. The conical nanopore functionalized with polyethylene glycol (PEG) 5 kDa is suitable for discrimination of the fibril size from relative current blockade. The bullet-like-shaped nanopore enhances the amplitude of the current and increases the dwell time, allowing us to well discern the fibrils. Finally, the nanopore crowded with PEG 20 kDa enhances the relative current blockade and increases the dwell time; however, the discrimination is not improved compared to the ``bullet-shaped'' nanopore.