Yi Feng, Kim Il Kyoon, Li Song, Lavan David A
Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899.
J Pharm Sci. 2014 Nov;103(11):3442-3447. doi: 10.1002/jps.24187. Epub 2014 Sep 24.
The phase transition evolution with hydration of a model system, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), was investigated with a fast nanocalorimetry system. Using nanocalorimetry, it is possible to measure the gel to liquid phase transitions that occur on millisecond to second time scales and quantify the time to recover the hydrated state. The results show the phase transition occurring in a few milliseconds and the relaxation or recovery time from the dehydrated state back to original hydrated state occurring with times dependent on the local humidity. With relative humidity (RH) of 43% or higher, the recovery time can be less than a few seconds. With RH of 11% or lower, the recovery time is extended to greater than a minute. The recovery process is controlled by mechanisms that depend on the lipid molecular repacking and water transport from the environment. Nanocalorimetry provides a powerful method to investigate the kinetics of such transformations in lipids and other biological and pharmaceutical moieties.
利用快速纳米量热系统研究了模型体系1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）水化过程中的相变演化。使用纳米量热法，可以测量在毫秒到秒时间尺度上发生的凝胶到液相转变，并量化恢复水合状态的时间。结果表明，相变在几毫秒内发生，从脱水状态恢复到原始水合状态的弛豫或恢复时间取决于局部湿度。相对湿度（RH）为43%或更高时，恢复时间可少于几秒。相对湿度为11%或更低时，恢复时间延长至超过一分钟。恢复过程由取决于脂质分子重新排列和来自环境的水传输的机制控制。纳米量热法为研究脂质以及其他生物和药物部分中此类转变的动力学提供了一种强大的方法。
