Critical point drying of brain tissue for X-ray phase-contrast imaging
Safe Khan1, Jonas Albers2, Artem Vorobyev3
1Sensory Circuits and Neurotechnology Laboratory, The Francis Crick Institute, London, United Kingdom.
Journal of Synchrotron Radiation
|March 23, 2026
Summary
Critical point drying (CPD) enhances X-ray phase contrast imaging of brain tissue by replacing interstitial material with air. This method preserves ultrastructure and improves signal, enabling detailed subcellular and ultrastructural analysis.
Area of Science:
- Biophysics
- Neuroscience
- Materials Science
Background:
- X-ray phase-contrast tomography offers high-resolution imaging of biological tissues.
- Current sample preparation methods limit the full potential of X-ray contrast mechanisms for ultrastructural analysis.
Purpose of the Study:
- To develop an optimized sample preparation method for enhanced X-ray phase contrast imaging of brain tissue.
- To improve the visualization of ultrastructural features by increasing X-ray phase shift signals.
Main Methods:
- Critical point drying (CPD) was used to remove interstitial material from heavy-metal-stained mouse brain tissue.
- Synchrotron-based microtomography and nanoscale holographic tomography were employed for imaging.
- CPD samples were compared to conventionally resin-embedded samples.
Main Results:
- CPD preserved the ultrastructure of brain tissue, creating a compatible nanofoam-like material.
- CPD samples exhibited 2-4 times stronger phase-shift signals compared to resin-embedded samples.
- The method is compatible with subsequent femtosecond laser milling and electron microscopy.
Conclusions:
- CPD is a versatile technique for preparing biological tissues for high-resolution X-ray imaging.
- This approach enhances X-ray phase contrast, improving signal and retaining structural detail.
- CPD facilitates advanced biological tissue imaging beyond the cubic millimeter scale.
