Polyene antibiotic amphotericin B in monomolecular layers: spectrophotometric and scanning force microscopic analysis.

Monolayers of amphotericin B (AmB) and monolayers composed of AmB and dipalmitoylphosphatidylcholine (DPPC) were formed at the argon-water interface and deposited on a solid support by means of the Langmuir-Blodgett technique. The hypsochromic shift observed in the absorption spectra of monolayers is indicative of aggregated structures of AmB. The exciton splitting theory allowed us to calculate the distance between neighboring molecules in the aggregates as 7.8 A. Scanning force microscopy of the AmB monolayers revealed the formation of a homogeneous monolayer composed of molecules separated by a distance of 6-8 A. Microscopy also reveals the formation of cylindrical structures of AmB with a diameter close to 17 A (internal diameter close to 6 A) in the monolayers containing additionally 10 mol% DPPC.