|Ph.D Student||Shalel Sagit|
|Subject||The Effect of Surfactants on Red Blood Cells|
|Department||Department of Chemical Engineering||Supervisors||Professor Emeritus Abraham Marmur|
|Dr. Sara Shtreichman|
In this work, the effects of surfactants on red blood cells were studied in order to determine the dominant hemolysis mechanism: osmotic lysis or solubilization. To distinguish between these mechanisms, the effect of solute size on the rate of hemolysis was examined, at constant ionic strength of the suspending solution. The effect of suspending solution composition on surfactant-induced hemolysis was also studied by gradually replacing an electrolytic solute (NaCl) with non-electrolytes (sugars). It was found that the amount of membrane-bound surfactant is strongly influenced by the ionic strength of the solution. It was also shown that a transition between the osmotic mechanism and solubilization could be induced for the same surfactant at the same concentration, just by varying the ionic strength.
To determine the amount of membrane-bound surfactant, the surfactant partition between the erythrocytes and suspending solution was evaluated using either the mass conservation law or a partition model. Contrary to previous works it was demonstrated that in order to quantify the analysis using these methods the complete hemolysis curve is required. The results imply that equilibrium was maintained between the membrane-bound surfactant and the bulk surfactant throughout the hemolysis process. A simple partition model, using a constant partition coefficient was used to describe this equilibrium.
Two additional methods were used to distinguish between osmotic hemolysis and solubilization: statistical analysis and surface tension measurements. Using a statistical analysis, the failure rate function, which best characterizes the hemolysis process, was elucidated. It was demonstrated that the osmotic mechanism could be described by the two-parameter Weibull distribution. When the hemolysis process involved solubilization, the Weibull distribution was not sufficient to describe the hemolysis rate. Using surface tension measurements, the osmotic mechanism clearly demonstrated three stages: increase, constancy, and decrease. When solubilization became significant in the hemolysis process a fluctuational increase in surface tension was observed.