CELL. MOL. BIOL. LETT., Vol. 4, No. 2, p. 280, 1999

INFLUENCE OF BOLAAMPHIPHILIC STEROID DIMER ON FORMATION AND STRUCTURE OF BILAYER LIPID MEMBRANES

Sławomir Kalinowski 1, Zenon Łotowski 2, Jacek W. Morzycki 2

1 University of Agriculture and Technology, Department of Chemistry, 10-957 Olsztyn-Kortowo, Poland
2 University of Białystok, Institute of Chemistry, Al. J. Piłsudskiego 11/4, 15-443 Białystok, Poland

The self-assembling formation process and the electromechanical properties of bilayer lipid membranes were investigated. The membranes were made of phosphatidylcholine with addition of the following steroid dimer:

The membranes were formed using Mueller-Rudin method. The formation of membranes in the presence of the dimer was much faster and they were more stable. The membranes formed by this method usually contain residues of solvent used in the formation process, increasing membrane thickness. The membranes made of phosphatidylcholine had average thickness 5.9 nm. Addition of the steroid dimer to the forming solution caused decrease of the thickness to 3.9 nm.

An external voltage applied to bilayer lipid membranes causes the electrocompression phenomenon. Membranes containing solvent inside the hydrophobic layer have high electrocompressibility. The solvent present inside the membranes is moved to the Plateau-Gibbs border surrounding the bilayer. Presence of the bolaamphiphilic steroid dimer in the membranes decreases the electrocompressibility about 20 times. The dimer molecules “span” monolayers of the membranes forcing lower thickness during their formation and restrict mobility of solvent inside the membranes. Addition of the dimer improves properties of the membranes, which are applied as model biomembranes and support for sensors based on biomembrane molecules.