We theoretically study the molecular-weight dependence of DNA thermophoresis, which arises from mutual advection of the n repeat units of the molecular chain. As a main result we find that the dominant driving forces, i.e., the thermally induced permittivity gradient and the electrolyte Seebeck effect, result in characteristic hydrodynamic screening. In comparison with recent experimental data on single-stranded DNA (2 ≤ n ≤ 80), our theory provides a good description for the increase of the drift velocity up to n = 30; the slowing-down of longer molecules is well accounted for by a simple model for counterion condensation. It turns out that thermophoresis may change sign as a function of n: for an appropriate choice of the salt-specific Seebeck coefficient, short molecules move to the cold and long ones to the hot; this could be used for separating DNA by molecular weight.

中文翻译：

---

DNA热泳中的水动力相互作用†

我们从理论上研究了DNA热泳的分子量依赖性，这是由于分子链的n个重复单元相互平流而引起的。作为主要结果，我们发现主要的驱动力，即热诱导的介电常数梯度和电解质塞贝克效应，导致了特征性的流体动力学筛选。在与单链DNA（2≤最近的实验数据进行比较Ñ ≤80），我们的理论提供了漂移速度高达增加一个很好的描述Ñ = 30; 一个抗衡离子缩合的简单模型很好地解释了较长分子的减速。事实证明，热泳可能会改变符号作为n的函数：为盐特异性塞贝克系数的适当选择，短分子移动到冷和长的人的热; 这可用于通过分子量分离DNA。