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

Area of Science:

• Biomaterials Science
• Biophysics
• Chemical Biology

Background:

• Cross-β peptide structures are crucial in functional biomaterials and disease-related aggregates.
• Understanding the nucleation and aggregation pathways of these paracrystalline assemblies is challenging.

Purpose of the Study:

• To apply fluorescence lifetime imaging microscopy (FLIM) to characterize critical peptide aggregation stages.
• To investigate the folding pathway of amyloid-beta (Aβ) using a model system.

Main Methods:

• Utilized fluorescence lifetime imaging microscopy (FLIM) with a rhodamine-labeled peptide (Rh110-Aβ(17-22)) as an intrinsic fluorescence reporter.
• Studied the central nucleating core of Aβ, specifically Aβ(16-22), as a model cross-β system.
• Investigated the impact of interfaces and evaporation on sub-critical concentration solutions.

Main Results:

• Mapped the folding pathway from monomer to paracrystalline nanotube for Aβ(16-22).
• Observed previously uncharacterized intermediate morphologies influenced by interfaces and evaporation.
• Tracked local peptide environment changes during nucleation and hydrophobic collapse using fluorescence lifetime.

Conclusions:

• FLIM provides a novel method to study dynamic peptide nucleation and maturation processes.
• The study offers a new metric for measuring fluorescence lifetimes of intrinsic reporters in peptide aggregation.
• Revealed the influence of environmental factors on the early stages of amyloid aggregation.