Phase transition in dioctadecyldimethylammonium bromide and chloride vesicles prepared by different methods
Phase transition in dioctadecyldimethylammonium bromide and chloride vesicles prepared by different methods
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DOI：
10.1016/s0009-3084(00)00127-4
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发表时间：
2000-04-01
影响因子：
3.4
通讯作者：
Olofsson, G
中科院分区：
文献类型：
--
作者：
Feitosa, E;Barreleiro, PCA;Olofsson, G
采用高灵敏度差示扫描量热法（DSC）研究了双链阳离子双十八烷基二甲基氯化铵和溴化铵（DODAX，X = Cl-或Br-）在非超声、超声和挤出法制备的囊泡水分散液中的凝胶相到液晶相的转变。转变温度（T-m）是制备方法、两亲物浓度、囊泡曲率和反离子性质的函数。DODAB和DODAC非超声处理囊泡分散体的DSC热分析图在T-m处显示出一个吸热峰，该峰与高达10 mM的浓度大致无关。挤出加宽了过渡峰，并使T-m向下移动。然而，超声处理稍微加宽了过渡峰，并且倾向于向上移动T-m，这表明挤出和超声处理形成具有不同特征的囊泡。无论采用何种制备方法，DODAC的T-m总是高于DODAB。T-m变化如下：T-m（超声处理）大于或等于T-m（非超声处理）> T-m（挤出）。对于DODAB囊泡分散体观察到约7 ° C的滞后。(C)2000爱思唯尔科学爱尔兰有限公司保留所有权利。
The gel to liquid crystalline phase transition of the double-chained cationic dioctadecyldimethylammonium chloride and bromide (DODAX, X = Cl- or Br-) in aqueous vesicle dispersions prepared by non-sonication, sonication and extrusion has been investigated using high-sensitivity differential scanning calorimetry (DSC). The transition temperature (T-m) is a function of the preparation method, amphiphile concentration, vesicle curvature and nature of the counterion. DSC thermograms for DODAB and DODAC non-sonicated vesicle dispersions exhibit a single endothermic peak at T-m roughly independent of concentration up to 10 mM. Extrusion broadens the transition peak and shifts T-m downwards. Sonication, however, broadens slightly the transition peak and tends to shift T-m upwards suggesting that extrusion and sonication form vesicles with different characteristics. DODAC always exhibits higher T-m than DODAB irrespective of the preparation method. T-m changes as follows: T-m (sonicated) greater than or equal to T-m (non-sonicated) > T-m (extruded). Hysteresis of about 7 degrees C was observed for DODAB vesicle dispersions. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.