Oversampling To Improve Spatial Resolution for Liquid Extraction Mass Spectrometry Imaging.

Area of Science:

• Analytical Chemistry
• Biomedical Imaging
• Mass Spectrometry

Background:

• Liquid extraction mass spectrometry imaging (LE-MSI) enables direct analysis of biological surfaces with minimal sample preparation.
• Increasing spatial resolution in LE-MSI traditionally involves reducing sampling area, which presents experimental challenges.

Purpose of the Study:

• To introduce and validate oversampling as a method to enhance spatial resolution in nanospray desorption electrospray ionization mass spectrometry imaging (nano-DESI MSI).
• To investigate potential drawbacks of oversampling, specifically molecular depletion and analyte redistribution during repeated sampling events.

Main Methods:

• Application of oversampling technique in nano-DESI MSI experiments on rat spinal cord tissue sections.
• Analysis of ion images for representative endogenous molecules to assess depletion and redistribution effects.
• Comparison of imaging results obtained with oversampling versus undersampling.

Main Results:

• Oversampling in nano-DESI MSI did not lead to significant depletion of endogenous molecules from the tissue.
• Analyte redistribution was not observed as a consequence of the oversampling process.
• A three-times oversampling strategy demonstrably increased spatial resolution, revealing previously unresolvable tissue features.

Conclusions:

• Oversampling is a viable and simple method to improve spatial resolution and image quality in LE-MSI techniques like nano-DESI MSI.
• The technique is effective without compromising molecular integrity through depletion or redistribution.
• Further validation is recommended for specific applications, but oversampling offers a promising approach for enhanced MSI analysis.