Two-Photon Excited Polarization-Dependent Autofluorescence of Amyloids as a Label-Free Method of Fibril Organization Imaging

J Phys Chem Lett. 2021 Feb 11;12(5):1432-1437. doi: 10.1021/acs.jpclett.0c03511. Epub 2021 Feb 1.

Abstract

Amyloids are broadly investigated protein misfolding products with characteristic β-sheet assemblies that have an important role in neurodegenerative diseases (e.g., Alzheimer's disease). While they are usually visualized by staining with Thioflavin-T, Congo Red, or other fluorescent markers, it still arouses a controversy over possible staining molecule influence on the amyloid structure or aggregation process. In this work we present, for the first time, the polarization analysis of two-photon excited autofluorescence of amyloids and confirm that polarization dependence of the observed emission can be correlated with the orientation of fibrils. We show the potential of two-photon excited autofluorescence for resolution of molecular organization of fibrils within amyloid superstructures. This label-free method is compatible with two-photon imaging already applied in investigation of neurodegeneration model in mice.

MeSH terms

  • Alzheimer Disease / metabolism*
  • Amyloid beta-Peptides / chemistry*
  • Amyloid beta-Peptides / metabolism*
  • Fluorescence Polarization
  • Fluorescent Dyes / chemistry*
  • Humans
  • Kinetics
  • Microscopy, Fluorescence, Multiphoton / methods
  • Optical Imaging
  • Protein Conformation

Substances

  • Amyloid beta-Peptides
  • Fluorescent Dyes