Ice Recrystallization in a Solution of a Cryoprotector and Its Inhibition by a Protein: Synchrotron X-Ray Diffraction Study

Boris Zakharov, Alexander Fisyuk, Andy Fitch, Yves Watier, Anastasia Kostyuchenko, Dushyant Varshney, Michael Sztucki, Elena Boldyreva, Evgenyi Shalaev

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Ice formation and recrystallization is a key phenomenon in freezing and freeze-drying of pharmaceuticals and biopharmaceuticals. In this investigation, high-resolution synchrotron X-ray diffraction is used to quantify the extent of disorder of ice crystals in binary aqueous solutions of a cryoprotectant (sorbitol) and a protein, bovine serum albumin. Ice crystals in more dilute (10 wt%) solutions have lower level of microstrain and larger crystal domain size than these in more concentrated (40 wt%) solutions. Warming the sorbitol–water mixtures from 100 to 228 K resulted in partial ice melting, with simultaneous reduction in the microstrain and increase in crystallite size, that is, recrystallization. In contrast to sorbitol solutions, ice crystals in the BSA solutions preserved both the microstrain and smaller crystallite size on partial melting, demonstrating that BSA inhibits ice recrystallization. The results are consistent with BSA partitioning into quasi-liquid layer on ice crystals but not with a direct protein–ice interaction and protein sorption on ice surface. The study shows for the first time that a common (i.e., not-antifreeze) protein can have a major impact on ice recrystallization and also presents synchrotron X-ray diffraction as a unique tool for quantification of crystallinity and disorder in frozen aqueous systems.

Original languageEnglish
Pages (from-to)2129-2138
Number of pages10
JournalJournal of Pharmaceutical Sciences
Volume105
Issue number7
DOIs
Publication statusPublished - 1 Jul 2016

Keywords

  • calorimetry (DSC)
  • crystal defects
  • freeze drying/lyophilization
  • phase transition
  • proteins
  • X-ray powder diffractometry

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