Talk abstracts
Talk on Tuesday 03:00-03:15pm submitted by Joseph Holbrook
Enhancement of Lipid Signals in Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry with Ammonium Fluoride as a Matrix Additive
Joseph H. Holbrook (Ohio State Biochemistry Program), Emily R. Sekera, Arbil Lopez, Brian D. Fries, Fernando Tobias (Department of Chemistry and Biochemistry, The Ohio State University ), Kubra Akkaya (Department of Biological Chemistry and Pharmacology, The Ohio State University), Maria M. Mihaylova (Ohio State Biochemistry Program, Department of Biological Chemistry and Pharmacology, Comprehensive Cancer Center, The Ohio State University), Amanda B. Hummon (Ohio State Biochemistry Program, Department of Chemistry and Biochemistry, Comprehensive Cancer Center, The Ohio State University )
Abstract:
Lipids are an important macromolecule that play a key role in numerous biological events. Matrix assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a powerful tool being used to understand the spatial localization of lipids within biological systems. There have been many advances made for increasing the sensitivity of lipid species detected in mass spectrometry. Of particular interest, comatrix additives represent a simple means to increase lipid sensitivity without extensive modification to existing in-house protocols. We report the novel use of ammonium fluoride (NH4F) as a comatrix additive to enhance lipid detection in both dry drop and MSI studies.
We observed statistically significant lipid signal enhancement in dry drop analysis of a lipid standard mixture, ranging from 25–214% increase in signal intensity depending on lipid type using NH4F additive. Endogenous lipids in a HCT 116 colorectal cancer cell lysate displayed signal enhancement of 60–148% with NH4F. Lipid identifications in the HCT 116 cell line were validated by an in-house spectral library generated with LC-MS/MS data. Next, we evaluated spraying the matrix onto a lipid standard mix, where spraying is primarily employed in MALDI-MSI experiments. Interestingly, lipid enhancement was again observed in the standard mixture ranging from 31–259% with NH4F.
We then examined if the same trend would be observed in MALDI-MSI experiments. Similarly, we found enhancement in lipid signal in MALDI-MSI with the additive for a mouse liver tissue, ranging from 10–16% increase in signal. Lastly, we conducted single-cell MALDI-MSI of the HCT 116 cell line at 5 um spatial resolution +/- NH4F. Most lipids analyzed displayed a significant increase in lipid signal corresponding to a 12–38% increase in signal intensity with the additive versus without. In summary, we have found NH4F to be a broad-spectrum comatrix additive to enhance the sensitivity in lipid detection for MALDI analysis.
References:
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[2] S. T. P. Mezger, A. M. A. Mingels, O. Bekers, B. Cillero-Pastor, R. M. A. Heeren, Analytical and Bioanalytical Chemistry 2019, 411, 3709–3720.
[3]T. B. Angerer, J. Bour, J.-L. Biagi, E. Moskovets, G. Frache, J. Am. Soc. Mass Spectrom. 2022, 33, 760–771.
[4] S. R. Ellis, M. R. L. Paine, G. B. Eijkel, J. K. Pauling, P. Husen, M. W. Jervelund, M. Hermansson, C. S. Ejsing, R. M. A. Heeren, Nature Methods 2018, 15, 515–518.
Keywords: Mass Spectrometry, Ammonium Fluoride, Lipids