电场下离子型聚合物复合囊泡结构变化的分子动力学模拟

利用粗粒化分子动力学模拟研究了电场作用下离子型聚合物复合囊泡形变与破裂的过程.定量分析了囊泡破裂过程中的结构变化,包括囊泡的形变程度、破裂速度、组分分布以及破裂后的结构.研究表明,电场强度较弱时,囊泡表面所吸附的聚电解质首先脱落,囊泡由球形结构转变为椭球结构.随着电场强度增大,离聚物的离子侧基发生重新排布,囊泡表面电荷的有序结构被破坏,导致囊泡的结构无法维持而破裂,囊泡塌缩,分裂形成离聚物团簇,并进一步破裂为小尺寸的离聚物聚集体,均匀分散于溶液中.本文利用分子动力学模拟明确了电场中离子型高分子复合囊泡破裂过程的分子机理,为药物释放技术的优化及发展提供了理论支持.

Molecular Dynamics Simulation of Structural Variations of Ionic Polymeric Vesicles under Electric Field

Using coarse-grained molecular dynamics simulations， we studied the deformation and break of ionic polymeric vesicles under the external electric field. We systematically analyzed the structural variations of the polymeric vesicles during the breaking process（including deformation degree and break rate of the vesicles and redistri-bution of each component， etc.） and the structure of the disassembled vesicles. Our study shows that under the weak electric field， the adhered polyelectrolyte preferentially desorb from the vesicle surface， and the vesicle undergoes a spherical-to-ellipsoidal transition. As the electric field strength increases， the ionic side-groups of ionomer are rearranged， and the ordered structure of the vesicle surface charge is wrecked， resulting in vesicle collapse. The collapsed vesicle further disassembles into the ionomer clusters or tiny ionomer aggregates， which are uniformly dispersed in the solution. Our simulations clarify the mechanism for the breaking process of the ionic polymeric vesicle induced by electric field application on a molecular level， and provide insights into the development of drug release technologies.