Aβ-AMYLOID FIBRILS ARE SELF-TRIGGERED BY THE INTERFACIAL LIPID ENVIRONMENT AND LOW PEPTIDE CONTENT

BOLAÑO ALVAREZ, ALAIN;; CARUSO, BENJAMIN;; RODRIGUEZ, PABLO; PETERSEN, STEFFEN; FIDELIO, GERARDO D.

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2020

0743-7463

 We studied the surface properties ofAβ(1-40) amyloid peptide mixed with POPC (liquid state) or DSPC (solid state)phospholipids by using nano-structured lipid/peptide films (Langmuir monolayers).Pure Aβ(1-40) amyloid peptide forms insoluble monolayers without forming fibril-likestructures. In a lipid environment (phospholipid/Aβ(1-40) peptide mixtures), we observed thatboth miscibility and stability of the films depend on peptide content.  At low Aβ(1-40) amyloid peptide proportion (from 2.5 % to 10 % of peptide area proportion) we observedthe formation of fibril-like structure when mixed only with POPC lipid. The stability acquired by these mixed films is within 20-35 mN.m-1compatible with the equivalent surface pressure postulated for naturalbiomembranes.  Fibrils are clearly evidenceddirectly from the monolayers by using Brewster Angle Microscopy. The so-callednano-structured fibrils are Thioflavin T positive when observed withfluorescence microscopy. The amyloid fibril network at the surface was alsoevidenced by Atomic Force Microscopy when the films are transferred onto micasupport. Aβ(1-40) amyloid mixed with the solid DSPClipid showed an immiscible behavior in all peptide proportions without fibrilsformation. We postulated that theamyloid fibrillogenesis at the membrane can be dynamically nano-self-triggeredat the surface by the quality of the interfacial environment, i.e. the physicalstate of the water-lipid interface and the relative content of amyloid proteinpresent at the interface.