熵受限在纳流控生物分子分离系统中的应用

摘要

提出了生物分子在深度周期性变化纳米流控通道中输运的理论模型.该系统利用不同大小的非各向同性粒子处在两个平面组成的狭小空间时转动自由度受限制程度(熵受限)的不同来实现带电粒子的分离.基于一维简化模型,建立了有效迁移率与通道尺寸、分子大小以及外电场强度的关系的解析解,用于表明这些因素如何决定分子分离的效果.算例表明对于50, 150和300 bp的DNA片段,在低电场强度下,迁移率误差值在5%以下.该简化模型可用于分析和优化实际的纳滤分离系统,而无需做复杂的数值模拟, 省去了大量的物理实验过程.%This article proposes a theoretical model of molecular sieving through repeated nanofilter arrays consisting of alternative deep and shallow regions. The role of configurational entropy, which arises from the inaccessibility of some configurations of the molecule in the confined space of nanochannel, is clarified explicitly. It is demonstrated that the configurational entropy difference of anisotropic biomolecules of different sizes dominates the complex partitioning of these molecules over the nanofilter array. In addition,the relationship between the effective mobility and the nanofilter geometries, molecular transport parameters, and the strength of electric fields are described rigorously.As an example, the mobilities for 50,150 and 300 bp DNA molecules are calculatedusing this model,which matches the experimental data with a error less than 5%. This simplified model allows for fast analysis of nanofilter separation systems, without the need of complicated numerical simulations and physical experiments.