Aβ42 fibril and non-fibril oligomers characterization using a nanopipette

Secondary Nucleation of Aβ Revealed by Single-Molecule and Computational Approaches

Understanding the mechanisms underlying amyloid-β (Aβ) aggregation is pivotal in the context of Alzheimer's disease. This study aims to elucidate the secondary nucleation process of Aβ42 peptides by combining experimental and computational methods. Using a newly developed nanopipette-based amyloid seeding and translocation assay, confocal fluorescence spectroscopy, and molecular dynamics simulations, the influence of the seed properties on Aβ aggregation is investigated. Both fragmented and unfragmented seeds played distinct roles in the formation of oligomers, with fragmented seeds facilitating the formation of larger aggregates early in the incubation phase. The results show that secondary nucleation leads to the formation of oligomers of various sizes and structures as well as larger fibrils structured in β-sheets. From these findings a mechanism of secondary nucleation involving two types of aggregate populations, one released and one growing on the mother fiber is proposed.

Characterizing Prion-Like Protein Aggregation: Emerging Nanopore-Based Approaches

Prion-like protein aggregation is characteristic of numerous neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. This process involves the formation of aggregates ranging from small and potentially neurotoxic oligomers to highly structured self-propagating amyloid fibrils. Various approaches are used to study protein aggregation, but they do not always provide continuous information on the polymorphic, transient, and heterogeneous species formed. This review provides an updated state-of-the-art approach to the detection and characterization of a wide range of protein aggregates using nanopore technology. For each type of nanopore, biological, solid-state polymer, and nanopipette, discuss the main achievements for the detection of protein aggregates as well as the significant contributions to the understanding of protein aggregation and diagnostics.

Influence of Seed structure on Volume distribution of α-Synuclein Oligomer at Early Stages of Aggregation using nanopipette

Understanding α-synuclein aggregation is crucial in the context of Parkinson's disease. The objective of this study was to investigate the influence of aggregation induced by preformed seeding on the volume of oligomers during the early stages, using a label-free, single-molecule characterization approach. By utilizing nanopipettes of varying sizes, the volume of the oligomers can be calculated from the amplitude of the current blockade and pipette geometry. Further investigation of the aggregates formed over time in the presence of added seeds revealed an acceleration in the formation of large aggregates and the existence of multiple distinct populations of oligomers. Additionally, we observed that spontaneously formed seeds inhibited the formation of smaller oligomers, in contrast to the effect of HNE seeds. These results suggest that the seeds play a crucial role in the formation of oligomers and their sizes during the early stages of aggregation, whereas the classical thioflavin T assay remains negative.