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Computer simulations of sample preconcentration in carrier-free systems and isoelectric focusing in microchannels using simple ampholytes
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: 0000-0002-3444-9987
2015 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 36, no 19, 2386-2395 p.Article in journal (Refereed) Published
Abstract [en]

In this work, electrophoretic preconcentration of protein and peptide samples in microchannels was studied theoretically using the 1D dynamic simulator GENTRANS, and experimentally combined with MS. In all configurations studied, the sample was uniformly distributed throughout the channel before power application, and driving electrodes were used as microchannel ends. In the first part, previously obtained experimental results from carrier-free systems are compared to simulation results, and the effects of atmospheric carbon dioxide and impurities in the sample solution are examined. Simulation provided insight into the dynamics of the transport of all components under the applied electric field and revealed the formation of a pure water zone in the channel center. In the second part, the use of an IEF procedure with simple well defined amphoteric carrier components, i.e. amino acids, for concentration and fractionation of peptides was investigated. By performing simulations a qualitative description of the analyte behavior in this system was obtained. Neurotensin and [Glu1]-Fibrinopeptide B were separated by IEF in microchannels featuring a liquid lid for simple sample handling and placement of the driving electrodes. Component distributions in the channel were detected using MALDI- and nano-ESI-MS and data were in agreement with those obtained by simulation. Dynamic simulations are demonstrated to represent an effective tool to investigate the electrophoretic behavior of all components in the microchannel.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2015. Vol. 36, no 19, 2386-2395 p.
Keyword [en]
Isoelectric focusing, Mass spectrometry, Microchip, Preconcentration, Simulation
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-175914DOI: 10.1002/elps.201500120ISI: 000362187700003PubMedID: 26036978ScopusID: 2-s2.0-84957847418OAI: diva2:867088
Swedish Research Council

QC 20151104

Available from: 2015-11-04 Created: 2015-10-26 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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