冷冻 PEG-蔗糖-水溶液中 PEG 结晶的研究。I. 冻融过程中非平衡行为的表征。
Investigation of PEG crystallization in frozen PEG-sucrose-water solutions. I. Characterization of the nonequilibrium behavior during freeze-thawing.
机构信息
Department of Pharmaceutics, College of Pharmacy, 308 Harvard St. SE, University of Minnesota, Minneapolis, Minnesota 55455, USA.
出版信息
J Pharm Sci. 2010 Jun;99(6):2609-19. doi: 10.1002/jps.22040.
Our objective was to characterize the nonequilibrium thermal behavior of frozen aqueous solutions containing PEG and sucrose. Aqueous solutions of (i) sucrose (10%, w/v) with different concentrations of PEG (1-20%, w/v), and (ii) PEG (10%, w/v) with different concentrations of sucrose (2-20%, w/v), were cooled to -70 degrees C at 5 degrees C/min and heated to 25 degrees C at 2 degrees C/min in a differential scanning calorimeter. Annealing was performed at temperatures ranging from -50 to -20 degrees C for 2 or 6 h. Similar experiments were also performed in the low-temperature stage of a powder X-ray diffractometer. A limited number of additional DSC experiments were performed wherein the samples were cooled to -100 degrees C. In unannealed systems with a fixed sucrose concentration (10%, w/v), the T'g decreased from -35 to -48 degrees C when PEG concentration was increased from 1% to 20% (w/v). On annealing at -25 degrees C, PEG crystallized. This was evident from the increase in T'g and the appearance of a secondary melting endotherm in the DSC. Low-temperature XRD provided direct evidence of PEG crystallization. Annealing at temperatures <or=-40 degrees C did not result in crystallization and a devitrification event was observed above the T'g. In unannealed systems with a fixed PEG concentration (10%, w/v), the T'g increased from -50 to -40 degrees C when sucrose concentration was increased from 5% to 50%, w/v. As the annealing time increased (at -25 degrees C), the T'g approached that of a sucrose-water system, reflecting progressive PEG crystallization. A second glass transition at approximately -65 degrees C was evident in unannealed systems [10%, w/v sucrose and 10 (or 20%), w/v PEG] cooled to -100 degrees C. Investigation of the nonequilibrium behavior of frozen PEG-sucrose-water ternary system revealed phase separation in the freeze-concentrate. Annealing facilitated PEG crystallization.
我们的目标是描述含有 PEG 和蔗糖的冷冻水溶液的非平衡热行为。（i）蔗糖（10%，w/v）在不同浓度的 PEG（1-20%，w/v）和（ii）PEG（10%，w/v）在不同浓度的蔗糖（2-20%，w/v）存在下的水溶液以 5°C/min 的冷却速率冷却至-70°C，并以 2°C/min 的加热速率在差示扫描量热仪中加热至 25°C。在-50 至-20°C 的温度范围内退火 2 或 6 小时。在粉末 X 射线衍射仪的低温阶段也进行了类似的实验。还进行了少量额外的 DSC 实验，其中将样品冷却至-100°C。在固定蔗糖浓度（10%，w/v）的未退火系统中，当 PEG 浓度从 1%增加到 20%（w/v）时，T'g 从-35 降至-48°C。在-25°C 退火时，PEG 结晶。这从 T'g 的增加和 DSC 中出现的二次熔融吸热峰中可以明显看出。低温 XRD 提供了 PEG 结晶的直接证据。在<或=-40°C 的温度下退火不会导致结晶，并且在 T'g 以上观察到脱玻璃化事件。在固定 PEG 浓度（10%，w/v）的未退火系统中，当蔗糖浓度从 5%增加到 50%（w/v）时，T'g 从-50 增加到-40°C。随着退火时间的增加（在-25°C），T'g 接近蔗糖-水系统的值，反映出 PEG 逐渐结晶。在冷却至-100°C 的未退火系统[10%，w/v 蔗糖和 10（或 20%），w/v PEG]中可以明显看出第二个玻璃化转变约为-65°C。对冷冻 PEG-蔗糖-水三元体系的非平衡行为的研究表明，在冷冻浓缩物中发生了相分离。退火促进了 PEG 结晶。
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