Dielectric Cytometry with Three-Dimensional Cellular Modeling

Abstract

We have developed what we believe is an efficient method to determine the electric parameters (the specific membrane capacitance C(m) and the cytoplasm conductivity kappa(i)) of cells from their dielectric dispersion. First, a limited number of dispersion curves are numerically calculated for a three-dimensional cell model by changing C(m) and kappa(i), and their amplitudes Deltaepsilon and relaxation times tau are determined by assuming a Cole-Cole function. Second, regression formulas are obtained from the values of Deltaepsilon and tau and then used for the determination of C(m) and kappa(i) from the experimental Deltaepsilon and tau. This method was applied to the dielectric dispersion measured for rabbit erythrocytes (discocytes and echinocytes) and human erythrocytes (normocytes), and provided reasonable C(m) and kappa(i) of the erythrocytes and excellent agreement between the theoretical and experimental dispersion curves.

Dielectric inspection of erythrocytes

“…In the present paper, referring to our recently reported experimental data, we first demonstrate the capability of the DS to differentiate suspensions of different cell shapes [14][15][16]19]. The shapes of rabbit erythrocytes were controlled by pH regulation to form spherocytes (swollen erythrocyte), echinocytes, enlarged erythrocytes (expanded discocytes similar to stomatocytes), and discocytes.…”

“…Thus, with the exception of spherocytes, the application of these theories to the erythrocyte suspensions in the present study is merely an approximation. In order to perform a more accurate analysis, a numerical simulation based on the three-dimensional finite difference method (3D-FDM) was introduced, as described in detail elsewhere [15,21,22]. This simulation model is a cubic space with two parallel plate electrodes on the top and bottom borders of the space, which is filled with a continuous medium.…”

“…(Refer to the previous study [15] for details.) For the echinocytes, the representative shape was modeled as a sphere with its surface modified by sinusoidal functions.…”

“…Moreover, the intercellular space in the centrifuged sediment could be affected by the structure and deformability of the erythrocytes, and could thus be a source of error in evaluating / [13,14]. In order to solve these problems, a newly developed approach using numerical simulation with three-dimensional cellular modeling can be employed [15].…”

Modeling of Dielectric Permittivity of the Erythrocytes Membrane as a Three-Layer Model

“…This relaxation process is indentified as being of Maxwell-Wagner type [59,60] and termed β -relaxation [60,61]. Most the theoretical models which describe the cell suspen-sions focus on β and γ -relaxations [17,14,61,62], including the often employed Pauly-Schwan model [63], them account for the non-spherical shape of cells. The diluted solutions and whole blood with a hematocrit value of 86% have to be treated differently.…”