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Characterization of Linear and Branched Polyethylenimine (PEI) by ESI-MS and MALDI-TOF-MS



Kathleen M. Flynn, M Konaklieva, J P. Gu, Charles M. Guttman, S Wetzel


Polyethylenimine (PEI) is being used as a DNA transfection agent. Complexes of DNA and PEI are known to pass through the wall of a cell, and studies have reported that PEI s efficiency as a gene delivery vehicle depends on its molecular weight. Molecular biologist who performed these assays purchased commercial PEI, that was poorly characterized. This study attempted to characterized commercial PEI, both linear and branched, by the use of mass spectrometry. The molecular mass distribution (MMD) obtained from commercial polyethylenimine by electrospray ionization and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was compared. The results of these two techniques give distributions for the same PEI sample that were quite different and the difference may be caused by preferential desorption/ionization, preferential ion attachment, or degradation and fragmentation due to the desorption process.Polyethylenimine analyzed by electrospray shows preferential ion attachment to most molecules. A study with mono and divalent cations suggests the branched polyethylenimine contains cyclic molecules. A study with six different cations of varying radii provides a rational for their attachment.
ASMS Conference on Mass Spectrometry and Allied Topics


ESI, MALDI, mass spectrometry, polyethylenimine, polymer characterization


Flynn, K. , Konaklieva, M. , Gu, J. , Guttman, C. and Wetzel, S. (2003), Characterization of Linear and Branched Polyethylenimine (PEI) by ESI-MS and MALDI-TOF-MS, ASMS Conference on Mass Spectrometry and Allied Topics, [online], (Accessed July 25, 2024)


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Created December 31, 2002, Updated October 12, 2021