Electrokinetic and stability properties of cholesterol in aqueous NaCl and NaCl + bile salt solutions

Abstract

Experimental data on the electrophoretic mobility of cholesterol particles in aqueous NaCl and NaCl + bile salt solutions are employed for the estimation of the zeta potential (ζ) of the particles in these media. The results obtained through the use of the well known Smoluchowski formula are compared with those deduced from a more elaborate treatment [11] so as to study the relative influence of the relaxation and electrophoretic effects for these systems. The use of the parameter ζ² x ⁻¹ (x ⁻¹ being the double layer thickness) allows us to correlate the electrokinetic properties of cholesterol with its tendency to coagulate in suspension. The influence of pH and NaCl concentration on this parameter is first discussed. Furthermore, the zeta potential of cholesterol in the presence of a series of bile salts is used to study the stability conditions of such suspensions, the results being discussed in terms of the characteristics of the different bile salts in solution.