Organization of polyene antibiotic amphotericin B at the argon-water interface.

Amphotericin B (AmB) is a life-saving antibiotic, used to treat deep-seated mycotic infections. Both the therapeutic and toxic side effects of AmB are directly dependent on its molecular organization. Organization of AmB was studied in monocomponent monomolecular layers formed at the argon-water interface, by means of polarized and non-polarized electronic absorption spectroscopy and analyzed in terms of the exciton splitting theory. The results provide direct indication that AmB forms spontaneously dimers that can be assembled into molecular structures characterized by homogeneous orientational distribution in the monolayer, interpreted as cylindrical pores. The structures are not stable at surface pressures higher than 20 mN/m and therefore dimers are concluded as abundant molecular organization forms of AmB in biomembranes. Possibility of stabilization of the cylindrical structures, at higher surface pressures, by other molecules, e.g. sterols, is also discussed.