Soft X-ray induced radiation damage in thin freeze-dried brain samples studied by FTIR microscopy

Area of Science:

• Materials Science
• Biophysics
• Microscopy

Background:

• Synchrotron-based soft X-ray microscopy (XRM) enables nanoscale imaging but requires high radiation doses.
• High radiation doses can compromise the integrity of delicate biological samples.
• Understanding radiation damage is crucial for optimizing XRM protocols for biological tissues.

Purpose of the Study:

• To quantify soft X-ray radiation damage in freeze-dried brain tissue samples.
• To compare damage levels in freeze-dried tissue with other sample preparation methods.
• To investigate the interaction between biological samples and silicon nitride (Si3N4) substrates during XRM.

Main Methods:

• Soft X-ray microscopy (XRM) was used to expose thin freeze-dried brain tissue samples mounted on Si3N4 membranes.
• Fourier transform infrared microscopy (FTIR) was employed to assess radiation-induced changes in the tissue's vibrational architecture.
• Comparison with literature data for paraffin-embedded and hydrated samples was performed.

Main Results:

• Freeze-dried brain tissue exhibited general degradation of its vibrational architecture upon XRM exposure.
• The observed radiation damage was less severe compared to paraffin-embedded and hydrated biological samples.
• Novel, weak, and reversible interactions between the tissue and the Si3N4 membrane were identified.

Conclusions:

• Freeze-drying is a more radiation-damage-resilient preparation method for XRM of brain tissue compared to traditional methods.
• The findings highlight the complex interplay between sample preparation, substrate, and X-ray probe in XRM.
• Further research is needed to fully understand and mitigate radiation damage in nanoscale imaging of biological systems.