MS/MS methodology to improve subcellular mapping of cholesterol using TOF-SIMS

Area of Science:

• Mass spectrometry
• Surface analysis
• Biomolecular imaging

Background:

• Time-of-flight secondary ion mass spectrometry (TOF-SIMS) offers submicrometer resolution for molecular surface mapping.
• Biological applications often focus on membrane lipids like cholesterol, crucial for various cellular processes.
• Low signal intensity and reliance on known fragments limit current biomolecule mapping effectiveness.

Purpose of the Study:

• To identify and map novel cholesterol fragments using advanced TOF-SIMS techniques.
• To improve the sensitivity and specificity of cholesterol detection in biological samples.
• To enhance the prospects for detailed cholesterol distribution analysis in cellular studies.

Main Methods:

• Utilized MS/MS data from a prototype C60(+)/quadrupole time-of-flight mass spectrometer.
• Employed indium liquid metal ion gun (LMIG) imaging for high-resolution mapping.
• Validated fragment identification using a model system of cholesterol-doped J774 macrophages.

Main Results:

• Discovered previously unrecognized cholesterol fragments in single cells.
• Identified m/z 147 as the most specific diagnostic fragment for cholesterol.
• Achieved a 3-fold signal enhancement for cholesterol mapping using the new fragments.

Conclusions:

• The identified fragments significantly improve the capability for cholesterol mapping in biological and single-cell experiments.
• These findings unlock a wealth of previously inaccessible information within traditional TOF-SIMS spectra.
• This research advances the field of biomolecular imaging and lipid analysis.