Mapping amyloid-β(16-22) nucleation pathways using fluorescence lifetime imaging microscopy

• Published in: Soft matter 2014-06, Vol.10 (23), p.4162-4172
• Main Authors: Anthony, Neil R, Mehta, Anil K, Lynn, David G, Berland, Keith M
• Format: Article
• Language: English
• Subjects: Agglomeration; Amyloid beta-Peptides - chemical synthesis; Amyloid beta-Peptides - chemistry; Amyloid beta-Peptides - metabolism; Fluorescence; Hydrophobic and Hydrophilic Interactions; Imaging; Microscopy; Microscopy, Fluorescence; Nanostructure; Nucleation; Pathways; Peptide Fragments - chemical synthesis; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Peptides; Polymerization; Rhodamines - chemistry
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/c4sm00361f

The cross-β peptide architecture is associated with numerous functional biomaterials and deleterious disease related aggregates. While these diverse and ubiquitous paracrystalline assemblies have been widely studied, a fundamental understanding of the nucleation and aggregation pathways to these structures remains elusive. Here we highlight a novel application of fluorescence lifetime imaging microscopy in characterising the critical stages of peptide aggregation. Using the central nucleating core of the amyloid-β (Aβ), Aβ(16-22), as a model cross-β system, and utilising a small fraction of rhodamine labelled peptide (Rh110-Aβ(17-22)), we map out a folding pathway from monomer to paracrystalline nanotube. Using this intrinsic fluorescence reporter, we demonstrate the effects of interfaces and evaporation on the nucleation of sub-critical concentration solutions, providing access to previously uncharacterised intermediate morphologies. Using fluorescence lifetime we follow the local peptide environment through the stages of nucleation and hydrophobic collapse, ending in a stable final structure. This work provides a metric for future implementations of measuring fluorescence lifetimes of intrinsic fluorescence reporters during the very dynamic processes relating to peptide nucleation and maturation.