Zehe A, Ramírez A, Starostenko O
Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Apartado Postal 1505, 72000 Puebla, Pue., México.
Braz J Med Biol Res. 2004 Feb;37(2):173-83. doi: 10.1590/s0100-879x2004000200003. Epub 2004 Jan 30.
Electro-rotation can be used to determine the dielectric properties of cells, as well as to observe dynamic changes in both dielectric and morphological properties. Suspended biological cells and particles respond to alternating-field polarization by moving, deforming or rotating. While in linearly polarized alternating fields the particles are oriented along their axis of highest polarizability, in circularly polarized fields the axis of lowest polarizability aligns perpendicular to the plane of field rotation. Ellipsoidal models for cells are frequently applied, which include, beside sphere-shaped cells, also the limiting cases of rods and disks. Human erythrocyte cells, due to their particular shape, hardly resemble an ellipsoid. The additional effect of rouleaux formation with different numbers of aggregations suggests a model of circular cylinders of variable length. In the present study, the induced dipole moment of short cylinders was calculated and applied to rouleaux of human erythrocytes, which move freely in a suspending conductive medium under the effect of a rotating external field. Electro-rotation torque spectra are calculated for such aggregations of different length. Both the maximum rotation speeds and the peak frequencies of the torque are found to depend clearly on the size of the rouleaux. While the rotation speed grows with rouleaux length, the field frequency nu(p) is lowest for the largest cell aggregations where the torque shows a maximum.
旋转电场可用于测定细胞的介电特性，以及观察介电和形态特性的动态变化。悬浮的生物细胞和颗粒通过移动、变形或旋转对交变电场极化做出响应。在线性极化交变电场中，颗粒沿其极化率最高的轴取向，而在圆极化电场中，极化率最低的轴垂直于场旋转平面排列。细胞的椭球模型经常被应用，除了球形细胞外，还包括杆状和盘状的极限情况。人类红细胞由于其特殊形状，几乎不像椭球体。不同聚集数的缗钱状形成的附加效应提示了一个可变长度的圆柱体模型。在本研究中，计算了短圆柱体的感应偶极矩，并将其应用于人类红细胞缗钱状，这些缗钱状在旋转外场的作用下在悬浮导电介质中自由移动。计算了不同长度的此类聚集体的旋转电场转矩谱。发现最大旋转速度和转矩的峰值频率都明显取决于缗钱状的大小。虽然旋转速度随缗钱状长度增加，但对于转矩最大的最大细胞聚集体，场频率ν(p)最低。
