Separation and detection of individual Aβ aggregates by capillary electrophoresis with laser-induced fluorescence detection

Abstract

The separation and detection of individual amyloid beta (Aβ) aggregates by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was demonstrated. Samples were prepared with either Aβ (1-40) or Aβ (1-42) peptides and were characterized by CE with ultraviolet (UV) absorbance detection and transmission electron microscopy (TEM). Using thioflavin T (ThT) in the electrophoresis buffer, electrophoresis of aggregate-containing samples (5.0-s injection) produced up to several hundred narrow (< 20 ms FWHM [full width at half maximum]) fluorescence peaks. Injection of Aβ (1-40) monomer samples resulted in no additional peaks compared with controls. The CE-LIF results were validated by bulk ThT fluorescence measurements for the same samples. The potential of laser-induced fluorescence anisotropy (LIFA) with CE to characterize individual Aβ aggregates also was investigated.