Single cell matrix-assisted laser desorption/ionization mass spectrometry imaging.

Area of Science:

• Analytical Chemistry
• Cell Biology
• Biophysics

Background:

• Previous mass spectrometry imaging (MS imaging) of single cells was limited by spatial resolution (MALDI) or mass resolution/range (SIMS).
• High-resolution molecular analysis of individual cells is crucial for understanding cellular heterogeneity and function.

Discussion:

• This work presents a new MS imaging method combining high spatial resolution (7 μm pixel), high mass accuracy (<3 ppm), and high mass resolution (R = 100,000 at m/z = 200).
• The technique utilizes atmospheric-pressure matrix-assisted laser desorption/ionization (AP-MALDI) coupled with an Orbitrap mass spectrometer.
• A dedicated sample preparation protocol involving glutaraldehyde fixation and pneumatic spraying of matrix was developed.

Key Insights:

• Demonstrated the first single-cell MS imaging with simultaneous high spatial and mass resolution.
• Successfully identified numerous metabolites (e.g., adenine, guanine, cholesterol) and lipid classes (e.g., phospholipids, triglycerides) in single HeLa cells.
• High mass accuracy (<3 ppm) ensures confident compound identification.

Outlook:

• The developed method enables molecularly specific imaging of metabolites and lipids in native single cells.
• This technique holds significant potential for investigating metabolic changes and cellular heterogeneity.
• Future applications include detailed studies of disease mechanisms and drug responses at the single-cell level.