The erythrocyte membrane electric field and its functional role

A biophysical model for interaction of cells with a surface coat (glycocalyx). I. Electrostatic interaction profile

A model of the primary stage of cell-cell interaction is assumed, including not only the classical electrostatic and electrodynamic energies in the sense of DLVO theory but also steric interaction energy, the energy of specific and non-specific bonds and the energy due to changes of surface potential. Furthermore, in this paper, we exploit recent advances in the understanding of the structure of the cell surface (glycocalyx), assuming the fixed electrostatic charges (dissociated groups of the glycocalyx), to be space charge densities and the glycocalyx itself to be an adsorption layer. In this first part the profile of the electrostatic potential between two cells is calculated on the basis of the linear Poisson-Boltzmann equation (analytical integration) and discussed in dependence on charge densities of the glycocalyx, the separation distance between cells and the ionic strength of the suspension medium.

Charge distribution within cell surface coats of single and interacting surfaces--a minimum free electrostatic energy approach. Conclusions for electrophoretic mobility measurements

The fixed charge distribution in a cell surface coat model was calculated using a variational approach based on the minimum of electrostatic free energy. The influence of ionic strength on distribution was analyzed. It is shown that interaction with other coats or smooth surfaces changes the fixed charge distribution. The special effect of a possible membrane charge was calculated in addition. In this case there is a fixed, charge-free space near the membrane, depending on coat thickness, ionic strength and membrane charge/surface coat charge ratio. For several cases energies, electric potentials and fixed charge distributions are given. The general result is that fixed charge distribution is always composed of a constant space charge density over a part of or the whole surface coat and, with some exceptions, of a surface charge density at the border of the surface coat. Conclusions for electrophoretic mobility measurement interpretations are drawn.