Multiple, Sequential DESI Images from a Single Tissue Section at Different Spatial Resolution

Importance of the Topic

Desorption electrospray ionization (DESI) imaging is a powerful mass spectrometry–based surface analysis method that permits rapid, label‐free chemical mapping of biological tissues. The ability to non‐destructively acquire multiple images from a single section at varying spatial resolutions enhances molecular characterization and preserves sample integrity for subsequent histological analysis.

Objectives and Study Overview

This work demonstrates the feasibility of sequential DESI imaging on the same tissue section at both low and high spatial resolutions. Porcine and human liver samples were analyzed to show that critical lipid and metabolite distributions can be resolved without significant analyte delocalization, enabling a two‐step workflow: an initial survey scan followed by targeted high‐resolution imaging.

Methodology

Sample Preparation

• Cryo‐sectioning of snap‐frozen porcine and human liver to 15 µm thickness.
• No additional matrix or chemical treatment; sections thaw‐mounted on standard glass slides.

Sequential DESI Imaging

• First pass at 150 µm pixel size for porcine liver and 200 µm for human liver.
• Second pass focused on regions of interest at 50 µm resolution.
• Spray solvent: 90:10 methanol:water at 1.5 µL/min, 100 psi N₂, ±5 kV.

Used Instrumentation

• SYNAPT G2-Si High Definition Mass Spectrometer with enhanced DESI imaging source.
• Data acquisition and processing: MassLynx and HDI v1.3 software.

Key Results and Discussion

Mass spectra from individual pixels at both resolutions showed consistent lipid profiles, confirming minimal sample disruption. High‐resolution (50 µm) images provided improved morphological detail and clearer delineation of lipid species. Sequential imaging of human liver biopsy revealed distinct distributions of phosphatidylglycerol and phosphatidylethanolamine lipids in healthy versus tumor tissue, and allowed zoomed‐in mapping of tumor margins.

Benefits and Practical Applications

The described workflow offers:

• Rapid initial screening of large tissue areas at coarse resolution.
• Targeted high‐resolution imaging of regions of interest on the same section.
• Preservation of tissue for post‐DESI histology (e.g., H&E staining).
• Accurate mapping of lipid and small‐molecule biomarkers without analyte relocalization.

Future Trends and Opportunities

Advances may include integration of DESI imaging with other label‐free modalities, development of sub‐10 µm pixel sizes for single‐cell resolution, and automated workflows for clinical diagnostics. Combining DESI with ion mobility separation or on‐tissue derivatization could further expand chemical coverage and spatial detail.

Conclusion

This study confirms that sequential DESI imaging at different spatial resolutions on a single tissue section is feasible, nondestructive, and capable of preserving analyte localization. The approach streamlines correlating molecular distributions with histological features, enhancing applications in biomarker discovery and clinical tissue analysis.

Reference

1. Claude E., Jones E. Multiple Sequential DESI Images from a Single Tissue Section at Different Spatial Resolution. Waters Corporation, Wilmslow, UK; collaboration with Imperial College London. NRES Committee London–South East (Study ID 11/LO/0686). Supported by ERC Starting Grant No. 210356 and EU FP7 Intelligent Surgical Device project No. 3054940.