Effect of electroosmotic flow on the electrophoresis of a membrane-coated sphere along the axis of a cylindrical pore.

The electrophoresis of a membrane-coated spherical particle along the axis of a long, charged cylindrical pore was analyzed theoretically under the conditions of low surface potential and weak applied electrical field. The influences of the thickness of the double layer, the pore radius, the nature of the membrane layer, and the charged conditions of the particle and the pore on the electrophoretic behavior of the particle were investigated. The occurrence of the electroosmotic flow and the presence of the membrane layer were found to have a significant influence on the mobility of the particle. For instance, because the direction of electrophoresis does not depend solely on the applied electrical field and the nature of the charge carried by the particle, care must be taken in interpreting electrophoresis data. Furthermore, the magnitude of the electrophoretic mobility of a particle can show a local maximum as the concentration of electrolytes varies, which is of practical significance if electrophoresis is employed, for example, as a separation tool.