Improved spatial resolution in the imaging of biological tissue using desorption electrospray ionization

Area of Science:

• Analytical Chemistry
• Biomolecular Imaging
• Mass Spectrometry

Background:

• Desorption electrospray ionization (DESI) imaging is crucial for biomarker discovery and disease diagnosis by chemically characterizing biological samples.
• Existing DESI imaging resolution limits detailed analysis of complex tissue structures and their molecular distributions.

Purpose of the Study:

• To significantly enhance the spatial resolution of desorption electrospray ionization imaging.
• To enable high-resolution chemical characterization of biological tissues for improved biomarker discovery and disease diagnosis.

Main Methods:

• Optimization of experimental parameters for desorption electrospray ionization, including emitter capillary size, solvent composition, flow rate, and mass spectrometry settings.
• Utilized unmodified commercial mass spectrometry for enhanced imaging.
• Validated resolution improvements using mouse brain tissue, correlating phospholipid distributions with known morphological features.

Main Results:

• Achieved a spatial resolution of approximately 35 μm, a substantial improvement from the initial 180 μm.
• Successfully correlated specific phospholipids, such as PS (18:0/22:6) in grey matter and ST (24:1) in white matter, with resolved tissue features.
• Characterized temporal lipid profile changes in mouse ovaries during the ovulatory cycle, noting increased PI (38:4) and associated fatty acids post-ovulation.

Conclusions:

• Optimized DESI imaging parameters significantly enhance spatial resolution for detailed molecular analysis of biological tissues.
• The improved resolution facilitates precise lipid mapping in complex tissues and allows for the study of dynamic molecular changes during physiological processes like the ovulatory cycle.