Interactions of amphotericin B with phospholipids in Langmuir monolayers

Abstract

Mixtures of amphotericin B and synthetic phospholipids, differing in the saturation of the phosphatidylcholine acyl chains, such as dipalmitoyl phosphatidylcholine, palmitoyl-oleoyl phosphatidyl choline and dioleoyl phosphatidylcholine, have been studied as floating Langmuir monolayers at the air–water interface. The films were spread at room temperature on aqueous subphases of different pH (3, 6 and 10) and characterized by the surface pressure–area isotherms and compressional modulus–surface pressure plots. The interactions were examined by analyzing the phase transitions appearing on the course of the isotherms. Although no significant difference in the affinity of amphotericin B to saturated/unsaturated phospholipids has been found, the results obtained reveal the influence of the apolar structure of phosphatidylcholine chains on the stoichiometry of amphotericin B–phosphatidylcholine complexes.