Structural and thermal characterization of dioctadecyldimethylammonium bromide dispersions by spin labels
Structural and thermal characterization of dioctadecyldimethylammonium bromide dispersions by spin labels
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DOI：
10.1016/s0009-3084(01)00134-7
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发表时间：
2001-06-01
影响因子：
3.4
通讯作者：
Lamy-Freund, MT
中科院分区：
文献类型：
--
作者：
Benatti, CR;Feitosa, E;Lamy-Freund, MT
通过简单地将两亲物在水中混合并通过水浴超声处理获得的双十八烷基二甲基溴化铵（DODAB）分散体，用电子自旋共振（ESR）研究了在酰基链的第5和第16个碳上标记的硬脂酸及其甲酯衍生物。ESR谱表明，非超声分散体主要由一群DODAB囊泡形成，无论是在凝胶状态（T < T-m）还是在液晶状态（T > T-m）。在T-m附近，两相共存，热滞后约为3.2 ℃。在超声处理的DODAB分散体中，自旋标签指示两种不同的环境，即使对于远低于Tm的温度：一种类似于用非超声处理的样品获得的环境，凝胶相，另一种处于液晶状态。低于T-m存在的流体相域可以对应于双层片段的外围，据报道存在于超声处理的DODAB分散体中，或高曲率囊泡。(C)2001爱思唯尔科学爱尔兰有限公司保留所有权利。
Dioctadecyldimethylammonium bromide (DODAB) dispersions obtained by simply mixing the amphiphile in water, and by bath-sonication, were investigated by electron spin resonance (ESR) of stearic acids and their methyl ester derivatives, labeled at the 5th and 16th carbons of the acyl chain. The ESR spectra indicate that the non-sonicated dispersions are formed mainly by one population of DODAB vesicles, either in the gel (T < T-m) or in the liquid-crystalline (T > T-m) state. Around T-m there is a co-existence of the two phases, with a thermal hysteresis of about 3.2 degreesC. In sonicated DODAB dispersions, spin labels indicate two different environments even for temperatures far below T-m: one similar to that obtained with non-sonicated samples, a gel phase, and another one in the liquid-crystalline state. The fluid phase domain present below T-m could correspond to either the periphery of bilayer fragments, reported to be present in sonicated DODAB dispersions, or to high curvature vesicles. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.