INTERACTIONS OF ERYTHROCYTES WITH AN ARTIFICIAL WALL - INFLUENCE OF THE ELECTRICAL SURFACE-CHARGE

Electrical charge on any biological surface plays a crucial role in it s interaction with other molecules or surfaces. Here, we study, under flow conditions, the interactions of erythrocyte. with an artificial s urface: a platinum microelectrode whose charge density ranges from -15 to +27 mu C/cm(2). This artificial surface could be similar in surfac e charge to an endothelium or a biomaterial. In this model, interactio ns are measured as a transient relative increase of the electrolyte re sistance obtained by impedance measurement of a microelectrode. A maxi mal interaction of erythrocytes viith the charged surface is calculate d in the 0 to +10 mu C/cm(2) charge density range. At negative surface charge, a less efficient contact was obtained because of electrostati c repulsion forces. High positive surface charge (charge density >10 m u C/cm(2)) does not improve the contact but induces a progressive decr ease in the contact efficiency, which could be explained by a re arran gement of macromolecules on the erythrocyte surface or an effect of po sitive groups on the cell membrane. This work suggests that a greater surface area of contact is obtained in the 0 to +10 mu C/cm(2) charge density range and that this is provided by more molecular bridges.