Mass Spectrometry Imaging Maps Intact Proteins in Tissue

Localized liquid extraction enables high-resolution imaging of intact proteins

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A nano-DESI mass spectrometry imaging protocol mapped intact protein forms in tissue at approximately 10-μm spatial resolution.
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The workflow uses ethanol and chloroform washes to remove lipids and precipitate proteins, limiting ion suppression and protein movement.
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A shear-force probe stabilizes the liquid bridge and maintains the sampling tip’s distance from the tissue surface.
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Mouse brain images showed spatial distributions of proteoforms, including modified myelin basic protein and cytochrome c oxidase subunit 6B1.
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Current nano-DESI experiments typically detect tens of proteoforms, with sensitivity, ionization efficiency, spectral processing, and fragmentation identified as areas for improvement.

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