层状液晶中的磁化转移
Magnetization transfer in lamellar liquid crystals.
作者信息
Malyarenko Dariya I, Zimmermann Ellen M, Adler Jeremy, Swanson Scott D
机构信息
Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.
出版信息
Magn Reson Med. 2014 Nov;72(5):1427-34. doi: 10.1002/mrm.25034. Epub 2013 Nov 20.
PURPOSE
This study examines the relationship between quantitative magnetization transfer (qMT) parameters and the molecular composition of a model lamellar liquid crystal (LLC) system composed of 1-decyl alcohol (decanol), sodium dodecyl sulfate (SDS), and water.
METHODS
Samples were made within a stable lamellar mesophase to provide different ratios of total semisolid protons (SDS + decanol) to water protons. Data were collected as a function of radiofrequency power, frequency offset, and temperature. qMT parameters were estimated by fitting a standard model to the data. Fitting results of four different semisolid line shapes were compared.
RESULTS
A super-Lorentzian line shape for the semisolid component provided the best fit. The estimated amount of semisolids was proportional to the ratio of decanol-to-water protons. Other qMT parameters exhibited nonlinear dependence on sample composition. Magnetization transfer ratio (MTR) was a linear function of the semisolid fraction over a limited range of decanol concentration.
CONCLUSION
In LLC samples, MT between semisolid and water originates from intramolecular nOe among decanol aliphatic chain protons followed by proton exchange between decanol hydroxyl and water. Exchange kinetics is influenced by SDS, although SDS protons do not participate in MT. These studies provide clinically relevant range of semisolid fraction proportional to detected MTR.
目的
本研究考察了定量磁化转移（qMT）参数与由1-癸醇（癸醇）、十二烷基硫酸钠（SDS）和水组成的层状液晶（LLC）模型系统的分子组成之间的关系。
方法
在稳定的层状中间相中制备样品，以提供不同比例的总半固体质子（SDS + 癸醇）与水质子。数据作为射频功率、频率偏移和温度的函数进行收集。通过将标准模型拟合到数据来估计qMT参数。比较了四种不同半固体线形的拟合结果。
结果
半固体成分的超洛伦兹线形提供了最佳拟合。估计的半固体量与癸醇与水质子的比例成正比。其他qMT参数对样品组成表现出非线性依赖性。在癸醇浓度的有限范围内，磁化转移率（MTR）是半固体分数的线性函数。
结论
在LLC样品中，半固体与水之间的MT源于癸醇脂肪链质子之间的分子内nOe，随后是癸醇羟基与水之间的质子交换。交换动力学受SDS影响，尽管SDS质子不参与MT。这些研究提供了与检测到的MTR成比例的临床相关半固体分数范围。
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