Interactions of erythrocytes with an artificial wall: influence of the electrical surface charge.

Electrical charge on any biological surface plays a crucial role in its interaction with other molecules or surfaces. Here, we study, under flow conditions, the interactions of erythrocytes with an artificial surface: a platinum microelectrode whose charge density ranges from -15 to +27 microC/cm2. This artificial surface could be similar in surface charge to an endothelium or a biomaterial. In this model, interactions are measured as a transient relative increase of the electrolyte resistance obtained by impedance measurement of a microelectrode. A maximal interaction of erythrocytes with the charged surface is calculated in the 0 to +10 microC/cm2 charge density range. At negative surface charge, a less efficient contact was obtained because of electrostatic repulsion forces. High positive surface charge (charge density > 10 microC/cm2) does not improve the contact but induces a progressive decrease in the contact efficiency, which could be explained by a rearrangement of macromolecules on the erythrocyte surface or an effect of positive groups on the cell membrane. This work suggests that a greater surface area of contact is obtained in the 0 to +10 microC/cm2 charge density range and that this is provided by more molecular bridges.