Generation of the streaming potential by liposomes in cylindrical capillary. Experimental data

A model of creation a streaming potential U as a result of colloidal particle movement in flow in a capillary has been described previously (Zawada 1996) as well as the systems for measurement (Zawada 1990, 1991). The filling of capillary with a solution of liposomes results in a labile adsorbance of liposomes on a capillary glass and changes the measured streaming potential. In order to minimalize these adverse effects, the capillary was covered with phospholipid layer of different composition. Some concentrations of stearylamine as a component of the phospholipid layer may fully compensate the surface charge of the glass capillary and can reduce the liposomes adsorption. The streaming potential of the liposomes solution depends on the ionic strength of the electrolyte and is smaller than the zeta potential for similar liposomes. This suggests that only a part of ions of the liposome ion atmosphere participate in creating of the streaming potential. These are the ions from the hydrodynamic slipping layer. The regression analysis of the relationships between streaming potential U and concentration of liposomes and next ionic strength of the electrolyte gave the value of the surface potential psi0 and the thickness of the hydrodynamic slipping layer d, that is independent of the ionic strength.