From Big Medical Encyclopedia

ELECTROKINETIC PHENOMENA — the phenomena caused by existence on the phase boundary of a disperse system of a double electric layer and ability of a diffusion part of this layer to be displaced it is rather adsorptive the connected, its motionless part. On E. I. many methods of studying are based proteins (see), amino acids (see), purine bases (see), pirimidinovy bases (see), monosaccharides (see), and also a research of viruses (see. Virologic researches ), cellular organellas and separate cells (see. Cell , Mikroionoforez ). The electrokinetic phenomena are the cornerstone also of the methods used in a wedge. to medicine for simplification of penetration of pharmaceuticals into cells and fabrics (see. Electrophoresis, medicinal electrophoresis ).

K E. I. belong electrophoresis (see) — the directed movement of the loaded microparticles and molecules in liquid (usually water) Wednesday under the influence of constant external electric field, and also electroosmosis (see) — the movement of a liquid phase, most often, solution of electrolyte (see. Electrolytes ), along walls of a capillary tube or the surface of channels time in a cellular body under the influence of external electric field. K E. I. also emergence in a motionless fluid column of potential difference (potential of sedimentation, or potential of sedimentation) at sedimentation of charged particles of a dispersed phase (Dorn's effect) belongs, and also emergence of potential difference (capacity of the current) at breakdown of liquid through a capillary tube or through a cellular body. The electrokinetic phenomena are closely connected with such processes as polarization (see) and conductivity of biological systems (see).

As a result of adsorption of ions from a dispersion medium and dissociation of superficial ionizable polar group (carboxyl, hydroxylic, amino groups, etc.) on a surface of particles of a dispersed phase there is electric charge. Electric charges of a surface of a particle form with the ions of a dispersion medium loaded opposite, a double electric layer. Thanks to it on border a particle — an environment is created potential difference. Electric potential on the interphase boundary carries the name electrokinetic or zeta-potential. The size of electrokinetic potential serves as a measure of intensity E. I. Electrokinetic potential of a cellular surface plays a part in power of a cell, in regulation of flows of substances through cellular membranes (see. Membranes biological , Transport of ions ), in mechanisms of contacts between cells and between a cell and Wednesday (see. Bioelectric phenomena ).

At change of the conditions influencing structure of a double electric layer the size of electrokinetic potential inevitably changes, edges depends also from fiziol. state and features of cells. Bacteria, e.g., at adsorption on a surface of cells of various components of culture medium, including and decomposition products of the died organisms, have a change of electrokinetic parameters of a cellular surface. Culture conditions and the environment of a research can have significant effect on structure of ionizable group and the adsorptive capacity of a surface of bacterial cells. At the person at various patol. states change of size of electric charge of a surface of cells can be a consequence of structural change of a cellular membrane and (or) structure of the pericellular environment; e.g., at many malignant tumors observe natural changes of electrokinetic parameters of cellular surfaces of uniform elements of blood.

Bibliography: Biophysics, under the editorship of B. N. Tarasov and O. R. Necklace, page 277, M., 1968; Martin R. Introduction to biophysical chemistry, the lane with English, page 218, M., 1966; Frayfelder D. Physical biochemistry, the lane with English, page 223, M., 1980.

Yu. B. Kudryashov, G. V. Sumarukov.