Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Medical Laboratory Technology, 1103 Clinical Sciences, 1702 Cognitive Sciences, General Clinical Medicine, 3202 Clinical sciences, 3205 Medical biochemistry and metabolomics

Abstract:

Background. Clinical diagnostics of Alzheimer‘s disease (AD) focuses on the determination of relative ratios of amyloid-β-peptides (Aβ-peptides) Aβ1-42 and Aβ1-40 in cerebrospinal fluid (CSF). Enrichment of such low abundance peptides on solid phase extraction (SPE) beads in combination with mass spectrometry (MS) provides a technique to detect biomarkers in body fluids. Methods. Miniaturisation of the SPE technique allowed capturing and subsequent analysis of the secreted Aβ-peptides from body fluids. Salt load and high abandoned liquor proteins were depleted while simultaneously Aβ-peptides where enriched from cerebrospinal fluid on one single SPE bead. Single SPE beads were transferred to a matrix-assisted laser desorption/ionization (MALDI) target and peptides were directly eluted with 2,5-Dihydroxyacetophenone matrix and subsequently analysed on a Bruker Ultraflex MALDI-TOF/TOF with high confidence. CSF from non-demented controls spiked with different Aβ-peptides was tested against AD patient liquor. Results. Spiked CSF samples allowed an efficient enrichment procedure with subsequent MALDI analysis within minutes. Aβ-peptide concentrations comparably with literature values (< 1µM) could be detected in sample volumes < 50µl. Peptides from patients with high unspecific protein back round (blood brain barrier defects) could still be detected. AD patient samples were tested, peak intensities/areas were determined and compared with the clinical results. Conclusions. The single bead technique enabled a fast and sensitive analysis of Aβ-peptides in low sample volume even against high protein background.