On-line aptamer affinity solid-phase extraction direct mass spectrometry for the rapid analysis of α-synuclein in blood

• Published in: Analytica chimica acta Vol. 1256; p. 341149
• Main Authors: Salim, Hiba, Pont, Laura, Giménez, Estela, Benavente, Fernando
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 22.05.2023
• Subjects: alpha-Synuclein; Aptamer; Biomarkers; Capillary electrophoresis; In-line solid-phase extraction; Limit of Detection; Mass spectrometry; Mass Spectrometry - methods; Oligonucleotides; Protein; Solid Phase Extraction - methods; α-synuclein; Aptamer; Capillary electrophoresis; In-line solid-phase extraction; Mass spectrometry; α-synuclein; Protein
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2023.341149

On-line aptamer affinity solid-phase extraction direct mass spectrometry (AA-SPE-MS) is presented for the rapid purification, preconcentration, and characterization of α-synuclein (α-syn), which is a protein biomarker related to Parkinson's disease. Valve-free AA-SPE-MS is easily implemented using the typical SPE microcartridges and instrumental set-up necessary for on-line aptamer affinity solid-phase extraction capillary electrophoresis-mass spectrometry (AA-SPE-CE-MS). The essential requirement is substituting the application of the separation voltage by a pressure of 100 mbar for mobilization of the eluted protein through the capillary towards the mass spectrometer. Under optimized conditions with recombinant α-syn, repeatability is good in terms of migration time and peak area (percent relative standard deviation (%RSD) values (n = 3) are 1.3 and 6.6% at 1 μg mL−1, respectively). The method is satisfactorily linear between 0.025 and 5 μg mL−1 (R2 > 0.986), and limit of detection (LOD) is 0.02 μg mL−1 (i.e. 1000, 500, and 10 times lower than by CE-MS, direct MS, and AA-SPE-CE-MS, respectively). The established AA-SPE-MS method is further compared with AA-SPE-CE-MS, including for the analysis of α-syn in blood. The comparison discloses the advantages and disadvantages of AA-SPE-MS for the rapid and sensitive targeted analysis of protein biomarkers in biological fluids. [Display omitted] •An aptamer affinity sorbent for the protein biomarker α -synuclein is prepared.•An on-line AA solid-phase extraction direct mass spectrometry method is developed.•The valve free AA-SPE-MS is a straightforward adaptation from AA-SPE-CE-MS.•Up to 500-fold sensitivity enhancement compared to direct MS is obtained.•A rapid and accurate analysis of human α-synuclein in blood samples is achieved.