UV-responsive vesicle was prepared by incorporating azobenzene in the vesicular membrane composed of dimethylaminopropyl octadecanamide (DMAPODA) and stearic acid (SA). Azobenzene intercalated in the vesicular membrane underwent cis-to-trans isomerization under the UV irradiation, confirmed by UV spectroscopy. The phase transition temperature of vesicle was found to be around 51.2 °C by differential scanning calorimetry. Using a negative staining technique, the vesicles were found as circular and irregular-shaped particles on the TEM photo. The mean hydrodynamic diameter of vesicles increased from 199.4 to 1597.3 nm when the lipid/azobenzene ratio increased from 100/0 to 100/5. The zeta potential of DMAPODA/SA vesicle decreased from about + 60 mV to – 60 mV when the pH value of medium increased from 3.0 to 10.0, and the inclusion of azobenzene in the vesicular membrane had little effect on the zeta potential. UV irradiation markedly promoted the release of carboxylic fluorescein loaded in vesicle incorporating azobenzene, possibly because the cis-to-trans photoisomerization would disturb the well-ordered crystalline structure of the vesicular membrane.

中文翻译：

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偶氮苯二甲氨基丙基十八酰胺/硬脂酸囊泡的制备及其紫外响应释放性能

通过在由二甲基氨基丙基十八酰胺（DMAPODA）和硬脂酸（SA）组成的囊泡膜中加入偶氮苯制备紫外线响应囊泡。通过紫外光谱证实，嵌入在囊泡膜中的偶氮苯在紫外光照射下发生顺反异构化。通过差示扫描量热法发现囊泡的相变温度约为 51.2°C。使用负染色技术，在 TEM 照片上发现囊泡为圆形和不规则形状的颗粒。当脂质/偶氮苯比例从100/0增加到100/5时，囊泡的平均流体动力学直径从199.4增加到1597.3 nm。当培养基的 pH 值从 3.0 增加到 10.0 时，DMAPODA/SA 囊泡的 zeta 电位从大约 +60 mV 下降到 – 60 mV，囊泡膜中包含偶氮苯对zeta电位的影响很小。紫外线照射显着促进了包含偶氮苯的囊泡中装载的羧基荧光素的释放，这可能是因为顺反光异构化会扰乱囊泡膜的有序晶体结构。