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Macromolecular separations based on the ion focusing in divergent asymmetric electric fields of switchable polarity
Afolayan, Adetayo S. Thurman, Hayden A. Tajaddodi, Atena
Afolayan, Adetayo S.
Thurman, Hayden A.
Tajaddodi, Atena
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Afolayan_2026.pdf
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2026-03-24
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Mass spectrometry is a powerful analytical technique used to study biological molecules such as proteins. Traditionally, molecules are separated before analysis using methods like chromatography or electrophoresis. Ion mobility separation, a technique that distinguishes molecules based on how they move through an electric field (E), has recently been integrated. Macroions with strong permanent dipoles align even at moderate field E without significant heating. This alignment affects how the ions drift, providing a characteristic that can be used for separation. We developed a new theoretical framework that describes how ions drift and focus within asymmetric electric fields. With the superposed dispersion voltage and compensation voltage, the ensuing actual fields scale proportionally throughout the gap. Hence, the ion focusing anywhere is governed by the super/sublinearity of equilibrium compensation field (EC) versus local dispersion field (ED). The accepted link between focusing waveform polarity and EC sign stays with superlinear EC(ED) scaling, while the sublinear scaling focuses in the opposite polarity. We validated these projections using larger proteins (kDa): carbonic anhydrase (29), alcohol dehydrogenase (37), and albumin (66), which yield abundant monomer and oligomer ions. The EC(ED) functions for pendular conformers are largely linear, superlinear in the low-field region and sublinear at higher ED. This allows fractionating protein ensembles based on the curvature of K(E) and EC(ED). This selection is tunable by flipping the focusing in the hemispherical region via electrode translation. This research improves protein separation and analysis, critical for understanding disease mechanisms, identifying biomarkers, and discovering drug targets, thereby supporting drug development.
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Poster project completed at Wichita State University, Department of Chemistry
Presented at the 23rd Annual Capitol Graduate Research Summit, Topeka, KS, March 24, 2026.
Presented at the 23rd Annual Capitol Graduate Research Summit, Topeka, KS, March 24, 2026.
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Wichita State University