Three groups of 1,2-dipalmitoyl-rac-glycero-3-phosphocholine (DPPC) large unilamellar vesicle (LUV) dispersions were studied: LUV (A) dispersions with only extraliposomal sodium chloride (NaCl), LUV (B) dispersions with intra- and extraliposomal NaCl, and LUV (C) dispersions with only intraliposomal NaCl. The NaCl concentrations ranged from 0 to 150 mM. An abrupt increase in leakage was observed around –10°C for all the three groups of LUV, which coincided with the temperature of extraliposomal ice formation. Within the three groups, leakage of LUV (C) was significantly higher than the other groups. Extraliposomal ice formation and the resulting freeze-concentration of LUV may be the major cause of the leakage. Intraliposomal ice formation observed at –43°C seemed to stop leakage of LUV when LUV were frozen below –43°C. An exotherm of eutectic crystallization of NaCl was occasionally observed at –37°C, with a higher probability of formation at 150 mM extraliposomal NaCl than at 50 mM. The eutectic crystals were thought to cause additional leakage from the LUV (B).
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LARGE UNILAMELLAR VESICLES;
Document Type: Research Article
November 1, 2007
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CryoLetters is a bimonthly international journal for low temperature sciences, including cryobiology, cryopreservation or vitrification of cells and tissues, chemical and physical aspects of freezing and drying, and studies involving ecology of cold environments, and cold adaptation
The journal publishes original research reports, authoritative reviews, technical developments and commissioned book reviews of studies of the effects produced by low temperatures on a wide variety of scientific and technical processes, or those involving low temperature techniques in the investigation of physical, chemical, biological and ecological problems.