Langer A, Kaiser W, Svejda M, Schwertler P, Rant U
Walter Schottky Institute and Chemistry Department, Technische Universität München , 85748 Garching, Germany.
J Phys Chem B. 2014 Jan 16;118(2):597-607. doi: 10.1021/jp410640z. Epub 2014 Jan 7.
Self-assembled monolayers of charged polymers are an integral component of many state-of-the-art nanobiosensors. Electrical interactions between charged surfaces and charged biomolecules, adopting the roles of linkers or capture molecules, are not only crucial to the sensor performance but may also be exploited for novel sensing concepts based on electrically actuated interfaces. Here we introduce an analytical model describing the behavior of double-stranded DNA and proteins tethered to externally biased microelectrodes. Continuum electrostatic Poisson-Boltzmann models and the drift-diffusion (Smoluchowski) equation are used to calculate the steady state as well as the dynamic behavior of oligonucleotide rods in DC and AC electric fields. The model predicts the oligonucleotide orientation on the surface and calculates how the increased hydrodynamic drag caused by a protein bound to the DNA's distal end affects the molecular dynamics of the DNA-protein complex. The results of the model are compared to experiments with electrically switchable DNA layers, and very good agreement between theory and experiment is found. The hydrodynamic diameter of the bound protein can be analyzed from experimental data of the slowed motion of the DNA-protein conjugate with angstrom precision.
带电聚合物的自组装单分子层是许多先进纳米生物传感器的重要组成部分。带电表面与充当连接分子或捕获分子的带电生物分子之间的电相互作用，不仅对传感器性能至关重要，还可用于基于电驱动界面的新型传感概念。在此，我们引入一个分析模型，描述连接到外部偏置微电极上的双链DNA和蛋白质的行为。连续静电泊松-玻尔兹曼模型和漂移-扩散（斯莫卢霍夫斯基）方程用于计算寡核苷酸棒在直流和交流电场中的稳态以及动态行为。该模型预测表面上寡核苷酸的取向，并计算与DNA远端结合的蛋白质所引起的流体动力学阻力增加如何影响DNA-蛋白质复合物的分子动力学。将模型结果与电可切换DNA层的实验进行比较，发现理论与实验非常吻合。结合蛋白质的流体动力学直径可从DNA-蛋白质共轭物运动减慢的实验数据中以埃精度进行分析。
