True density analysis of a freeze-dried amorphous sugar matrix
True density analysis of a freeze-dried amorphous sugar matrix
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DOI：
10.1002/jps.21202
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发表时间：
2008-07-01
影响因子：
3.8
通讯作者：
Nakanishi, Kazuhiro
中科院分区：
文献类型：
--
作者：
Imamura, Koreyoshi;Maruyama, Yoshinobu;Nakanishi, Kazuhiro
无定形基质的真密度表示基质中分子堆积的状态，其与材料的物理/化学性质密切相关。干气比重瓶法是一种用于测量通过冷冻干燥制备的无定形糖基质的真密度的可能技术。我们在此报告的影响，用于测比重瓶的测量密度值的条件，并提出了一个协议，用于获得真密度。该技术是足够准确的，以允许由不同类型的糖组成的矩阵的值进行比较。使用该协议，几个无定形糖样品含有不同类型的糖，冷冻干燥条件（温度和糖浓度在冷冻的糖水溶液的时间），预处理（压实和研磨）的真密度进行了测定和结果进行了比较。模拟无定形基质的糖（海藻糖）的模型构建使用分子动力学/力学计算，和模拟的糖基质的真密度被发现同意使用所提出的协议实验确定的值。利用模拟的无定形糖基质，讨论了基质中糖分子的真密度、分子间相互作用状态和应变之间的关系。(C)2007 Wiley-Liss，Inc.
True density of an amorphous matrix represents the state of molecular packing in the matrix, which is closely related to the physical/chemical properties of the material. Dry gas pycnometry is one possible technique for measuring the true density of an amorphous sugar matrix prepared by freeze-drying. We herein report on the influence of conditions used for pycnometry on the measured density value and propose a protocol for obtaining the true density. The technique is sufficiently accurate to permit values for matrices comprised of different types of sugar to be compared. Using the protocol, the true densities of several amorphous sugar samples containing different types of sugar, freeze-drying conditions (temperature and sugar concentration at the time of freezing of an aqueous sugar solution), pretreatment (compaction and grind) were determined and the results were compared. A model for simulating an amorphous matrix of sugar (trehalose) was constructed using molecular dynamics/mechanics calculations, and the true density of the simulated sugar matrix was found to agree with the value experimentally determined using the proposed protocol. The relationship among the true density, the states of intermolecular interactions, and strain of sugar molecules in the matrix are discussed using the simulated amorphous sugar matrix. (C) 2007 Wiley-Liss, Inc.