Changes in the X-ray diffraction pattern from lens during a solid-to-liquid phase transition
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Updated: Jun 18, 2026

A Package of Established Analytical Tools to Investigate the Solid-State Alteration of Lipid-Based Excipients
Published on: August 9, 2022
Justyn W Regini1, Keith M Meek
1The Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, CF24 4LU, UK. reginijw@cf.ac.uk
Purpose:
The purpose of this study is to compare the structural integrity of bovine lenses using small-angle X-ray diffraction techniques, before and after freezing, using both liquid nitrogen and a -20 degrees C freezer to understand the molecular changes that occur and to see if any permanent structural changes result from the freezing and thawing process.
Materials And Methods:
We used small-angle X-ray scattering to investigate the effects of freezing whole bovine eye lenses (i) in liquid nitrogen and (ii) at -20 degrees C, to better understand the structural basis of the phase transitions.
Results:
Lenses frozen in liquid nitrogen thawed more rapidly than those placed at -20 degrees C. With both freezing methods, X-ray patterns taken during the thawing process indicated less protein order than before or after freezing. After both freezing methods, the X-ray reflection returned to its original spacing and close to its original intensity values before freezing.
Conclusions:
We explain these phenomena in terms of a simple model based on the melting of ice crystals. We also suggest that the liquid nitrogen method of freezing is probably the better method of cryo-preservation for maintaining lens crystallin order.
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