Lörscher Christopher, Ala-Nissila Tapio, Bhattacharya Aniket
Department of Physics, University of Central Florida, Orlando, Florida 32816-2385, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Jan;83(1 Pt 1):011914. doi: 10.1103/PhysRevE.83.011914. Epub 2011 Jan 26.
We study polymer translocation through a nanopore subject to conformational differences created by putting two different solvents at the cis and trans compartments using Langevin dynamics in three dimensions (3D). Initially a fraction of the chain is placed in a good solvent at the cis side and the rest of the chain at the trans side is immersed in a bad solvent where it forms a globule. We study several aspects of the translocating chain as a function of the strength of the interaction ɛ/k(B)T for the bad solvent, where the temperature T is kept below the Θ temperature for the specific bead-spring model that we have used to describe the chain. For ɛ/k(B)T≥1 we find the mean first passage time (τ)(ɛ/k(B)T)(-1) and (τ)N(1.1±0.05). In that regard, translocation under solvent asymmetry is similar to the case of driven translocation under a bias inside the pore. However, the globule formed at the trans in the immediate vicinity of the pore readily absorbs the incoming particles making the translocation process faster than the driven translocation. Our simulation results for long chains and ɛ/k(B)T≥1 agree well with a theoretical prediction by Muthukumar [M. Muthukumar, J. Chem. Phys. 111, 10371 (1999).].
我们使用三维（3D）朗之万动力学研究聚合物通过纳米孔的转位过程，该过程受顺式和反式隔室中两种不同溶剂所产生的构象差异影响。最初，一部分链置于顺式侧的良溶剂中，而链的其余部分置于反式侧，浸没在不良溶剂中并形成小球。我们研究了转位链的几个方面，作为不良溶剂中相互作用强度ɛ/k(B)T的函数，其中温度T保持低于我们用于描述链的特定珠簧模型的θ温度。对于ɛ/k(B)T≥1，我们发现平均首次通过时间（τ）(ɛ/k(B)T)(-1)且（τ）N(1.1±0.05)。在这方面，溶剂不对称下的转位类似于孔内存在偏置时的驱动转位情况。然而，在孔紧邻的反式侧形成的小球很容易吸收进入的粒子，使得转位过程比驱动转位更快。我们对长链且ɛ/k(B)T≥1的模拟结果与Muthukumar的理论预测[M. Muthukumar, J. Chem. Phys. 111, 10371 (1999).]吻合得很好。
