动、静态光散射在线跟踪DPPC/PA脂质体的聚集和融合过程

Online Monitoring of the Aggregation and Fusion of DPPC/PA by Static and Dynamic Light Scattering

结合动、静激光光散射在线跟踪了经低温培养的二棕榈酰基磷脂酰胆碱/棕榈酸(摩尔比为1:2)脂质体在25-41℃温度范围内的聚集和融合过程.在升温过程中,脂质体的尺寸和相对分子质量明显增大,表明有聚集或融合发生.另外,尺寸分布出现角度依赖性,证明囊泡结构遭到破坏.而在接下来的降温过程中,粒径和相对分子质量继续增大,没有回到初始状态.根据光散射结果,我们认为脂质体富集脂肪酸分子的区域随温度升高会发生黏合而形成聚集,该聚集体形态类似反六方柱状相.融合发生的比例较小.降温过程中的变化表明囊泡是动力学稳定态,一旦聚集发生,会自发继续进行聚集或融合.

Static and dynamic light scattering were employed to monitor the temperature-induced aggregation and fusion processes of liposomes consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine （DPPC） and palmitic acid （PA） in a molar ratio of 1：2.From 25 to 41 ℃,the size and the relative molecular mass of the liposome increased with increasing temperature indicating the occurrence of aggregation or fusion.Meanwhile,the size showed strong angular dependence,suggesting that the vesicle structure was at least partially destroyed upon aggregation.During the subsequent cooling process,the size and relative molecular mass continued to increase.On the basis of these results,we propose that the aggregation is caused by the adhesion of liposomes in the palmitic acid rich zones.The formed aggregate had a structure between that of bilayers and inverted hexagonal （HII） packing.Upon aggregation,the ratio of fusion was small.Our results also indicated that the vesicle was kinetically stable.Once the transition from the gel state to semi-inverted hexagonal （HII） packing was triggered,the aggregation or fusion of the liposome proceeded automatically.