On-line Aptamer Affinity Solid-Phase Extraction Capillary Electrophoresis-Mass Spectrometry for the Analysis of Blood α-Synuclein

In this paper, an on-line aptamer affinity solid-phase extraction capillary electrophoresis-mass spectrometry method is described for the purification, preconcentration, separation, and characterization of alpha-synuclein (alpha-syn) in blood at the intact protein level. A single-stranded DNA aptamer is used to bind with high affinity and selectivity alpha-syn, which is a major component of Lewy bodies, the typical aggregated protein deposits found in Parkinson's disease (PD). Under the conditions optimized with recombinant alpha-syn, repeatability (2.1 and 5.4% percent relative standard deviation for migration times and peak areas, respectively) and microcartridge lifetime (around 20 analyses/microcartridge) were good, the method was linear between 0.5 and 10 mu g.mL(-1), and limit of detection was 0.2 mu g.mL(-1) (100 times lower than by CE-MS, 20 mu g.mL(-1)). The method was subsequently applied to the analysis of endogenous alpha-syn from red blood cells lysate of healthy controls and PD patients.