Pethig Ronald
Institute for Integrated Micro and Nano Systems, School of Engineering & Electronics, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3JF, UK.
Micromachines (Basel). 2022 Feb 6;13(2):261. doi: 10.3390/mi13020261.
Standard DEP theory, based on the Clausius-Mossotti (CM) factor derived from solving the boundary-value problem of macroscopic electrostatics, fails to describe the dielectrophoresis (DEP) data obtained for 22 different globular proteins over the past three decades. The calculated DEP force appears far too small to overcome the dispersive forces associated with Brownian motion. An empirical theory, employing the equivalent of a molecular version of the macroscopic CM-factor, predicts a protein's DEP response from the magnitude of the dielectric -dispersion produced by its relaxing permanent dipole moment. A new theory, supported by molecular dynamics simulations, replaces the macroscopic boundary-value problem with calculation of the cross-correlation between the protein and water dipoles of its hydration shell. The empirical and formal theory predicts a positive DEP response for protein molecules up to MHz frequencies, a result consistently reported by electrode-based (eDEP) experiments. However, insulator-based (iDEP) experiments have reported negative DEP responses. This could result from crystallization or aggregation of the proteins (for which standard DEP theory predicts negative DEP) or the dominating influences of electrothermal and other electrokinetic (some non-linear) forces now being considered in iDEP theory.
基于解决宏观静电学边值问题得出的克劳修斯 - 莫索蒂（CM）因子的标准介电泳（DEP）理论，无法描述过去三十年来针对22种不同球状蛋白质获得的介电泳（DEP）数据。计算出的DEP力似乎太小，无法克服与布朗运动相关的分散力。一种经验理论，采用宏观CM因子的分子版本等效物，根据蛋白质弛豫永久偶极矩产生的介电色散大小来预测蛋白质的DEP响应。一种得到分子动力学模拟支持的新理论，用计算蛋白质与其水化层水偶极之间的互相关来取代宏观边值问题。经验理论和形式理论预测，高达兆赫兹频率的蛋白质分子会有正的DEP响应，这一结果与基于电极的（eDEP）实验一致报道。然而，基于绝缘体的（iDEP）实验报道了负的DEP响应。这可能是由于蛋白质的结晶或聚集（标准DEP理论预测会有负的DEP），或者是iDEP理论中现在正在考虑的电热和其他电动（一些非线性）力的主导影响。
