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Sample preconcentration in open microchannels combined with MALDI-MS
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0003-3548-217X
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0002-3444-9987
2012 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 33, no 22, 3343-3350 p.Article in journal (Refereed) Published
Abstract [en]

In this work, a method for preconcentrating samples in 1 cm long, 50-150 μm wide open microchannels is presented. Platinum electrodes were positioned at the channel ends, voltage was applied, and charged analyte was preconcentrated at the oppositely charged side during continuous supply of sample. The preconcentration was initially studied in a closed system, where an influence on the analyte position from a pH gradient, generated by water electrolysis, was observed. In the open channel, the analyte distribution after preconcentration was evaluated using MALDI-MS with the channel as MALDI target. MALDI matrix was applied with an airbrush or by electrospray matrix deposition and by using the latter technique higher degrees of crystallization in the channels were obtained. After preconcentrating a 1 nM cytochrome c solution for 5 min, corresponding to a supplied amount of 1.25 fmol, a signal on the cathodic channel end could be detected. When a solution of cytochrome c trypsin digest was supplied, the peptides were preconcentrated at different positions along the channel depending on their charge.

Place, publisher, year, edition, pages
2012. Vol. 33, no 22, 3343-3350 p.
Keyword [en]
Electrospray deposition, MALDI-MS, Preconcentration, Silicon microchip
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:kth:diva-108041DOI: 10.1002/elps.201200129ISI: 000311303100013ScopusID: 2-s2.0-84869782576OAI: diva2:579424
Swedish Research Council

QC 20121220

Available from: 2012-12-20 Created: 2012-12-19 Last updated: 2016-09-30Bibliographically approved
In thesis
1. Electrophoretic focusing in microchannels combined with mass spectrometry: Applications on amyloid beta peptides
Open this publication in new window or tab >>Electrophoretic focusing in microchannels combined with mass spectrometry: Applications on amyloid beta peptides
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Analysis of low-abundance components in small samples remains a challenge within bioanalytical chemistry, and new techniques for sample pretreatments followed by sensitive and informative detection are required. In this thesis, procedures for preconcentration and separation of proteins and peptides in open microchannels fabricated on silicon microchips are presented. Analyte electromigration was induced by applying a voltage along the channel length, and detection was performed either by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) within the open channel, or by sampling a nL fraction containing the preconcentrated analytes from the channel for subsequent nano-electrospray ionization- (nESI-) or MALDI-MS. Utilizing solvent evaporation from the open system during sample supply, sample volumes exceeding the 25-75 nL channel volume could be analyzed. For preconcentration/separation of components in the discrete channel volume a lid of inert fluorocarbon liquid was used for evaporation control.

In Papers I and II, aqueous, carrier-free solutions of proteins and peptides were analyzed, and the method was successfully applied for fast and simple preconcentration of amyloid beta (Aβ) peptides, related to Alzheimer’s disease.

The impact of possible impurities in the analysis of carrier-free solutions was investigated in Paper III with the 1D simulation software GENTRANS, and a method for open-channel isoelectric focusing in a tailor-made pH gradient was developed. The latter approach was used in Paper IV for preconcentration and purification of Aβ peptides after immunoprecipitation from cerebrospinal fluid and blood plasma, followed by MALDI-MS from a micropillar chip.

Paper V includes simulations of an isotachophoretic strategy for selective enrichment of Aβ peptides. GENTRANS simulations were used to select the electrolyte composition, and 2D simulations in a geometry suitable for on-chip implementation were performed using COMSOL Multiphysics.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. 55 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:36
amyloid beta, computer simulation, electrophoresis, electrospray ionization, isoelectric focusing, isotachophoresis, MALDI, mass spectrometry, microchannel, microchip, nano-electrospray ionization, preconcentration, separation
National Category
Analytical Chemistry
Research subject
urn:nbn:se:kth:diva-193134 (URN)978-91-7729-142-8 (ISBN)
Public defence
2016-11-04, F3, Lindstedtsvägen 26, 10:00 (English)

QC 20160930

Available from: 2016-09-30 Created: 2016-09-29 Last updated: 2016-09-30Bibliographically approved

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Mikkonen, SaaraRokhas, Maria KhihonJacksén, JohanEmmer, Åsa
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