Advances and Pitfalls in the Capillary Electrophoresis Analysis of Aggregates of Beta Amyloid Peptides

Abstract

Alzheimer's disease is characterized by the accumulation of brain amyloid plaques composed of aggregates of amyloid β (Aβ) peptides. The present paper describes a novel and easy-to-run capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) method for the specific analysis of fibrillar forms of Aβ aggregates obtained after in vitro incubation of Aβ 1-40 monomer. For that purpose, an affinity CE-LIF approach in which the ligand thioflavine T was added to the running buffer has been used, leading to the separation and detection of various fibrillar aggregates which migrated as spikes. The procedure has been optimized to get spikes only corresponding to Aβ aggregates, through the careful elimination of interfering factors and the electrophoretic validation of the link between spikes and particulate material. This method exhibited semi-quantification capabilities, led to the separation of Aβ fibrillar aggregates of different sizes and showed that highly concentrated solutions of Aβ peptides led to the formation of aggregates of larger size than lower-concentrated solution did. Advances brought by this method as well as future development needed to overcome its present limitations are discussed.