流场驱动高分子链迁移穿过微通道的耗散粒子动力学模拟

利用耗散粒子动力学模拟方法研究了高分子链在流场驱动作用下迁移穿过微通道过程中的链构象变化和动力学行为.在足够大的流场力驱动作用下,高分子链在沿着流场方向逐渐被拉伸,从而能够穿过管径小于其自身尺寸的微通道.耗散粒子动力学模拟结果表明高分子链的迁移过程主要分为3个步骤:(1)在流场驱动作用下,高分子链漂移并逐渐靠近微通道入口;(2)高分子链逐渐调整自身构象,并使其部分进入微通道;(3)高分子链成功穿过微通道.同时,模拟还发现当高分子链尺寸大于微通道细管道管径时,高分子链穿过微通道所需的平均迁移时间随着流量的增加而逐渐减小.此外,为了研究高分子链刚性对高分子链穿过微通道的影响,模型中还引入了蠕虫状高分子链模型.模拟结果发现,高分子链的链刚性越强,其迁移穿过微通道的时间越长.

DISSIPATIVE PARTICLE DYNAMICS SIMULATIONS OF FLUID-DRIVEN POLYMER CHAINS THROUGH A MICROCHANNEL

The dynamics of fluid-driven translocation of polymers chains through a microchannel is investigated by dissipative particle dynamics(DPD) approach.Unlike implicit solvent models,this approach naturally preserves many-body energetic and hydrodynamic interactions by incorporating explicit solvent particles in this approach.An externally applied body force is exerted on each solvent particle to generate a Poiseuille flow in the microchannel,which drives the polymer chain across the narrow channel.The DPD simulations show that the polymer chain undergoes "affine-deformation",and three stages can be identified during the translocations:(1) the polymer chain initially drifts along the flow direction;(2) the polymer chain approaches the entrance of the narrow channel by undergoing a continuous conformational deformation to make its size match the pore size of the narrow channel,and part of polymer chain enter into the pore mouth of the narrow channel;(3) the polymer chain rapidly travels through the narrow channel to fulfill complete translocation.The results also show that the average translocation time steadily decreases with the increase of fluid flux.In addition,the results also demonstrate that chain rigidity exerts a considerable influence on the dynamics of polymer chain translocations,and the average translocation time steadily increases when the polymer becomes more rigid.These findings in this study may be helpful in understanding the dynamic behaviors of fluid-driven polymer and/or DNA molecules during the translocation processes.