Desorption of amphotericin B from mixed monolayers with cholesterol at theair/water interface

The desorption of amphotericin B (AmB) from mixed monolayers with cholester ol was studied by monitoring temporal changes in the relative area (A(t)/A( o)) as a function of time at constant surface pressures, corresponding to t hree distinct regions of the AmB isotherm, The loss of AmB molecules from t he interface was found to obey the Ter Minassian Saraga model [J, Colloid I nterface Sci. ii, 398 (1956)], In the low surface pressure region the overa ll process of desorption is controlled by a one-step dissolution (at small times) followed by diffusion. At high pressures, however, the process of di ssolution is more complex and consists of two steps that differ in rate. Th e presence of cholesterol molecules in the monolayer prevents the desorptio n of AmB molecules as evidenced by the constant desorption values. The anal ysis of the kinetics parameters confirms our previous findings, based on th e analysis of excess functions, that the highest interactions, due to the s table complex formation, appear for the mixture of X-AmB = 0.7 (C) 2001 Aca demic Press.