Department of Mechanical Engineering, Micro and Nano-scale Transport Laboratory, University of Alberta, Edmonton T6G 2G8, Canada.
Biomicrofluidics. 2010 Mar 1;4(1):14105. doi: 10.1063/1.3339773.
Myoglobin is one of the premature identifying cardiac markers, whose concentration increases from 90 pgml or less to over 250 ngml in the blood serum of human beings after minor heart attack. Separation, detection, and quantification of myoglobin play a vital role in revealing the cardiac arrest in advance, which is the challenging part of ongoing research. In the present work, one of the electrokinetic approaches, i.e., dielectrophoresis (DEP), is chosen to separate the myoglobin. A mathematical model is developed for simulating dielectrophoretic behavior of a myoglobin molecule in a microchannel to provide a theoretical basis for the above application. This model is based on the introduction of a dielectrophoretic force and a dielectric myoglobin model. A dielectric myoglobin model is developed by approximating the shape of the myoglobin molecule as sphere, oblate, and prolate spheroids. A generalized theoretical expression for the dielectrophoretic force acting on respective shapes of the molecule is derived. The microchannel considered for analysis has an array of parallel rectangular electrodes at the bottom surface. The potential and electric field distributions are calculated using Green's theorem method and finite element method. These results also compared to the Fourier series method, closed form solutions by Morgan et al. [J. Phys. D: Appl. Phys. 34, 1553 (2001)] and Chang et al. [J. Phys. D: Appl. Phys. 36, 3073 (2003)]. It is observed that both Green's theorem based analytical solution and finite element based numerical solution for proposed model are closely matched for electric field and square electric field gradients. The crossover frequency is obtained as 40 MHz for given properties of myoglobin and for all approximated shapes of myoglobin molecule. The effect of conductivity of medium and myoglobin on the crossover frequency is also demonstrated. Further, the effect of hydration layer on the crossover frequency of myoglobin molecules is also presented. Both positive and negative DEP effects on myoglobin molecules are obtained by switching the frequency of applied electric field. The effect of different shapes of myoglobin on DEP force is studied and no significant effect on DEP force is observed. Finally, repulsion of myoglobin molecules from the electrode plane at 1 KHz frequency and 10 V applied voltage is observed. These results provide the ability of applying DEP force for manipulating nanosized biomolecules such as myoglobin.
肌红蛋白是早期心肌损伤的标志物之一，其在人类血清中的浓度从 90pg/ml 或更低增加到 250ng/ml 以上。肌红蛋白的分离、检测和定量在提前揭示心脏骤停方面起着至关重要的作用，这是目前研究的挑战性部分。在本工作中，选择电泳（DEP）等电动方法之一来分离肌红蛋白。建立了一个数学模型来模拟微通道中肌红蛋白分子的介电泳行为，为上述应用提供了理论基础。该模型基于介电泳力和介电肌红蛋白模型的引入。通过将肌红蛋白分子的形状近似为球体、扁球体和长球体，建立了介电肌红蛋白模型。推导出了作用于分子各自形状的介电泳力的广义理论表达式。所分析的微通道在底部表面具有一系列平行的矩形电极。使用格林定理法和有限元法计算电位和电场分布。这些结果还与傅里叶级数法、Morgan 等人的解析解[J. Phys. D: Appl. Phys. 34, 1553 (2001)]和 Chang 等人的解析解[J. Phys. D: Appl. Phys. 36, 3073 (2003)]进行了比较。结果表明，对于所提出的模型，基于格林定理的解析解和基于有限元的数值解对于电场和正方形电场梯度非常吻合。对于给定的肌红蛋白性质和所有近似的肌红蛋白分子形状，获得了 40MHz 的交叉频率。还演示了介质和肌红蛋白的电导率对交叉频率的影响。此外，还介绍了水化层对肌红蛋白分子交叉频率的影响。通过切换施加电场的频率，获得了对肌红蛋白分子的正和负介电泳效应。研究了不同形状的肌红蛋白对介电泳力的影响，没有观察到介电泳力的显著影响。最后，在 1KHz 频率和 10V 施加电压下观察到肌红蛋白分子从电极平面的排斥。这些结果提供了应用介电泳力操纵纳米级生物分子（如肌红蛋白）的能力。
