title: Magneto-immunocapture with on-bead fluorescent labeling of amyloid-β peptides: towards a microfluidized-bed-based operation.
abstract: A new sample treatment approach for sensitive determination of three amyloid-β peptides (Aβ 1-42, Aβ 1-40 and Aβ 1-38) with capillary electrophoresis coupled with laser induced fluorescent detection is reported herein. These Aβ peptides are considered an important family of biomarkers in the cerebrospinal fluid (CSF) for early diagnosis of Alzheimer's disease (AD). Due to their extremely low abundance in CSF (down to sub nM ranges), batch-wise preconcentration via magneto-immunocapture with enrichment factors up to 100 was implemented. The Aβ peptides were first captured onto magnetic micro-beads. Then, on-beads fluorescent labeling of the captured Aβ peptides were carried out to avoid the unwanted presence of extra fluorescent dye in the eluent as in the case of in-solution labeling. Finally thermal elution was performed and eluted labeled peptides were analyzed off line with CE-LIF. The Aβ-capturing efficiencies of different commercially available antibodies grafted onto magnetic beads were tested. Aβ peptides in CSF samples collected from AD's patients and healthy persons (used as controls) were measured and evaluated. As a proof of concept, the developed strategy was adapted into a miniaturized fluidized bed configuration that has the potential for coupling with a microchip separation system.
authors.affiliation: Université Paris-Sud, Institut Galien Paris-Sud, 5 rue JB Clément, 92296 Châtenay-Malabry, France. claire.smadja@u-psud.fr.
authors.forename: Thanh Duc
authors.initials: TD
authors.lastname: Mai
authors.forename: Iago
authors.initials: I
authors.lastname: Pereiro
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hiraoui
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Viovy
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Descroix
authors.forename: Myriam
authors.initials: M
authors.lastname: Taverna
authors.forename: Claire
authors.initials: C
authors.lastname: Smadja
mesh_terms: D000544:Alzheimer Disease / Q000175:diagnosis; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid* / Q000276:immunology / Q000302:isolation & purification; D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology; D019075:Electrophoresis, Capillary; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D007834:Lasers; D008280:Magnetics; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D010446:Peptide Fragments / Q000134:cerebrospinal fluid* / Q000276:immunology / Q000302:isolation & purification; D013050:Spectrometry, Fluorescence / Q000295:instrumentation
chemical_list: D016229:Amyloid beta-Peptides; D055910:Antibodies, Immobilized; D005456:Fluorescent Dyes; D010446:Peptide Fragments; C078639:amyloid beta-protein (1-38); C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)