Three-dimensional mass spectral imaging of HeLa-M cells--sample preparation, data interpretation and visualisation

Area of Science:

• Biophysics
• Analytical Chemistry
• Cell Biology

Background:

• Time-of-flight secondary ion mass spectrometry (ToFSIMS) offers high lateral resolution for chemical imaging.
• Its application in biological systems is growing, requiring optimized sample preparation.
• Novel instrumentation, like the J105 3D Chemical Imager, enables advanced ToFSIMS analysis.

Purpose of the Study:

• To compare two distinct cell sample preparation methods for ToFSIMS.
• To evaluate the impact of sample preparation on 3D chemical imaging of biological cells.
• To demonstrate the advantages of a specific preparation technique for ToFSIMS analysis.

Main Methods:

• Comparison of fixed and freeze-dried versus non-fixed, frozen-hydrated cell preparation.
• Analysis using a novel buncher-ToF instrument (J105 3D Chemical Imager) with a C(60) primary ion beam.
• Application of multivariate analysis techniques for 3D data reconstruction.

Main Results:

• The non-fixed, frozen-hydrated preparation method significantly reduced chemical redistribution within cells.
• This method resulted in cleaner mass spectra compared to fixed, freeze-dried samples.
• Improved chemical contrast was observed in both 2D and 3D ToFSIMS imaging of cells.

Conclusions:

• Maintaining cells in a non-fixed, frozen-hydrated state is crucial for high-quality ToFSIMS chemical imaging.
• This preparation technique enhances spectral purity and imaging contrast in biological samples.
• The study provides insights into data interpretation and 3D reconstruction for ToFSIMS analysis.