Relevance of Hydrodynamic Effects for the Calculation of Outer Surface Potential of Biological Membrane Using Electrophoretic Data

Izan M Silva Junior,Maria Clícia S Castro,Dilson Silva,Célia M Cortez

doi:10.1590/0001-3765201620140530

Izan M Silva Junior, Maria Clícia S Castro + Show 2 more

Open Access

https://doi.org/10.1590/0001-3765201620140530

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Abstract

In this paper, we present the results of a study on the influence of hydrodynamic effects on the surface potentials of the erythrocyte membrane, comparing two different models formulated to simulate the electrophoretic movement of a biological cell: the classical Helmholtz-Smoluchowski model and a model presented by Hsu et al. (1996). This model considers hydrodynamic effects to describe the distribution of the fluid velocity. The electric potential equation was obtained from the non-linear Poisson-Boltzmann equation, considering the spatial distribution of electrical charges fixed in glycocalyx and cytoplasmic proteins, as well as electrolyte charges and ones fixed on the surfaces of lipidic bilayer. Our results show that the Helmholtz-Smoluchowski model is not able to reflect the real forces responsible to the electrophoretic behavior of cell, because it does not take account the hydrodynamic effects of glycocalyx. This charged network that covers cellular surface constitutes a complex physical system whose electromechanical characteristics cannot be neglected. Then, supporting the hypothesis of other authors, we suggest that, in electrophoretic motion analyses of cells, the classical model represents a limiting case of models that take into account hydrodynamic effects to describe the velocity distribution of fluid.

Highlights

The electric surface potential is an important control parameter of the cellular metabolic process (Cortez et al 2008, Genet et al 2001, Bruner 1986)
QS1 negativity caused a decrease of about 33% in the φSg-value (Figure 2(c)). This variation cannot be neglected, and it shows that charges in glycocalyx and on bilayer surfaces contribute to the potential difference responsible for the motion of erythrocytes in an electrophoretic field, the electrical double layer extends over only about 1 nm from lipidic bilayer surface in physiological conditions
Our results showed that values of electric potential of the surface cell generated by HS-equation do not reflect the real forces responsible for the electrophoretic cellular behavior

Summary

Introduction

The electric surface potential is an important control parameter of the cellular metabolic process (Cortez et al 2008, Genet et al 2001, Bruner 1986). The Helmholtz-Smoluchowski equation (HS-equation) is consider valid to estimate the electrical surface potential and charge density of cells from electrophoretic data (Eylar et al 1962), but its validity scale has been examined.

Results

Conclusion