Atomic and molecular imaging at the single-cell level with TOF-SIMS

Area of Science:

• Biophysics
• Analytical Chemistry
• Microscopy

Background:

• Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a surface-sensitive technique.
• Analyzing frozen hydrated biological samples presents challenges due to surface water interference.
• Submicrometer imaging requires precise sample preparation to preserve molecular integrity.

Purpose of the Study:

• To develop and validate a cold chain freeze-fracture methodology for TOF-SIMS imaging.
• To assess the feasibility of molecular analysis of frozen hydrated biological samples using TOF-SIMS.
• To demonstrate the capability of TOF-SIMS for imaging molecular species on cell surfaces.

Main Methods:

• A complete cold chain freeze-fracture technique was established.
• A cold trap at -196°C minimized surface water interference on samples at -97 to -113°C.
• Controlled sample warming was employed to manage matrix molecule volatility and surface morphology.

Main Results:

• The developed methodology successfully enabled TOF-SIMS imaging of frozen hydrated biological samples.
• Submicrometer resolution molecular imaging of cell surfaces was achieved.
• Images of hydrocarbons, DMSO, and cocaine were successfully obtained from Paramecium cells.

Conclusions:

• The cold chain freeze-fracture method is feasible for TOF-SIMS molecular analysis of frozen hydrated biological samples.
• TOF-SIMS imaging can provide detailed molecular distribution information at the submicrometer level on cell surfaces.
• This technique offers a novel approach for investigating the molecular landscape of biological specimens.