Amyloid-β Peptide–Lipid Bilayer Interaction Investigated by Supercritical Angle Fluorescence

Abstract

The understanding of the interaction between the membrane of neurons and amyloid-β peptides is of crucial importance to shed light on the mechanism of toxicity in Alzheimer's disease. This paper describes how supercritical angle fluorescence spectroscopy was applied to monitor in real-time the interaction between a supported lipid bilayer (SLB) and the peptide. Different forms of amyloid-β (40 and 42 amino acids composition) were tested, and the interfacial fluorescence was measured to get information about the lipid integrity and mobility. The results show a concentration-dependent damaging process of the lipid bilayer. Prolonged interaction with the peptide up to 48 h lead to an extraction and clustering of lipid molecules from the surface and a potential disruption of the bilayer, correlated with the formation of peptide aggregates. The natural diffusion of the lipid was slightly hindered by the interaction with amyloid-β(1−42) and closely related to the oligomerization of the peptide. The adsorption and desorption of Amyloid-β was also characterized in terms of affinity. Amyloid-β(1−42) exhibited a slightly higher affinity than amyloid-β(1−40). The former was also more prone to aggregate and to adsorb on the bilayer as oligomer.

Hydrogel-Coated Gate Field-Effect Transistor for Real-Time and Label-Free Monitoring of β-Amyloid Aggregation and Its Inhibition

“…Moreover, they are integrated in one device system including a temperature sensor using a conventional fabrication process . With this system, Aβ monomers, which are generated in the body, may be incorporated into the hydrogel on the gate surface or may be adsorbed and aggregated on the gate surface with the lipid bilayer, assuming interactions between the membrane of neurons and Aβ …”

Role of phosphatidylserine in amyloid-beta oligomerization at asymmetric phospholipid bilayers

“…In a recent report, on supercritical angle fluorescence measurements of Aβ oligomerization at a DOPC/DOPS (65/35) membrane, Seeger et al 55 hypothesized the following steps: 1) Aβ monomer adsorbs at the membrane, facilitated by longrange electrostatic interactions with anionic lipids; 2) Aβ monomers diffuse along the membrane and self-aggregate, concomitantly inducing lipid clustering that generate nanopores within the membrane, causing additional membrane strain; 3) further aggregation of Aβ removes some of the lipids that are tightly bound to the oligomer scaffold; and 4) the oligomer of Aβ is ejected from the membrane as a plaque leaving a porated/damaged membrane as shown schematically in Figure 1. 17,[26][27][28]55 Fig 1 . Hypothesized mechanism of amyloid-beta activity within a lipid bilayer proposed by Seeger et al 55 The majority of the membrane is made up of zwitterionic lipids (blue), and the amyloid beta peptide monomer (red) may adsorb to the membrane. Negatively charged lipids (green) attract amyloid beta peptides, causing the monomers to assemble within the membrane; however, some monomers may pull lipids from the membrane.…”

“…Furthermore, according to the hypothesized mechanism described in Figure 1, when Aβ self-assembly leads to larger scale oligomers/fibrils, they are released from the membrane into the contact solution. 55,99,100 To explore this, the contacting electrolyte solution from the impedance experiments after 24 hours of Aβ incubation with the membrane were collected and studied via UV/Vis and Fluorescence, following treatment with thioflavin T (Tht). Tht is a fluorescent probe is known to bind specifically to amyloid fibrils but not to amyloid monomers.…”

“…Ab-membrane interactions have been studied using a diverse of models, including liposomes, black lipid membranes, and supported lipid bilayer membranes (SLBs). 3,22,37,[55][56][57][58][59] However, there are challenges in addressing some aspects of Ab interaction. Liposomes for example, have a lack of control over compositional asymmetry, and are generally not addressable with surface-sensitive analytical tools.…”

Monitoring Non-Specific Adsorption at Solid-Liquid Interfaces by Supercritical Angle Fluorescence Microscopy

“…SAF has also been used, albeit rarely, to explore time-dependent phenomena. For example, dynamic SAF measurements were used to characterize amyloid-β peptide-bilayer interactions, revealing the dynamics of bilayer disruption 11 .…”