ELECTROPHORETIC MOBILITY OF BIOLOGICAL CELLS IN ASYMMETRIC ELECTROLYTE-SOLUTIONS

The electrophoretic mobility of a particle covered by a membrane in an a:b electrolyte solution is modeled theoretically. The membrane, whic h simulates the surface of a biological cell, is ion-penetrable, and c arries homogeneously distributed negative fixed charges. An approximat e expression for the electrophoretic mobility is derived. Based on the results of numerical simulation, we conclude the following: (1) The a bsolute Donnan potential increases with the concentration of the fixed charges Co, but decreases with the ionic strength 1. (2) The greater the valence of cation a, the lower the absolute potential distribution . (3) The greater the C-0, the greater the absolute mobility of a part icle, \mu\, and the greater the friction coefficient of the membrane p hase gamma, the smaller the \mu\. (4) A large I or a large a leads to a small \mu\. (5) The greater the ratio (permittivity of solution/perm ittivity of membrane phase), the smaller the \mu\. (6) For a large gam ma, \mu\ decreases with the thickness of membrane d under the conditio n of constant amount of fixed charges. However, if gamma is sufficient ly small, the variation of I lr I as a function of d exhibits a maximu m. The classic result of Smoluchowski for the electrophoretic mobility of a rigid particle can be recovered as a limiting case of the presen t model. (C) 1996 Academic Press Limited