Effect of ionic and neutral surfactants on the properties of phospholipid vesicles: investigation using fluorescent probes

Abstract

The effect of triton X-100, sodium dodecyl sulphate and cetyl trimethyl ammonium bromide on the physical properties of dimytistoyl phosphatidyl choline liposome was studied in the sublytic concentration range of the detergent, using the different fluorescence probes 8-anilino-1-naphthalene sulphonate, 1,6-diphenylhexatriene and 1-naphthol. Depending on the nature and concentration of the detergent, and the position of the hydrophilic and hydrophobic parts of different detergent in liposomes, the fluidity and permeability of the bilayers were affected. The fluidity decreases at very low concentrations of detergent owing to an improvement in the packing density of phospholipid molecules. The extent of changes in these properties was found to be dependent on the phase state of liposomes, being greater in the solid gel phase than in the fluid liquid crystalline phase. Also, the thermotropic phase transitions of the phospholipid bilayers are affected moderately by neutral surfactants and greatly by charged surfactants owing to an alteration in the water of hydration of the lipid molecules.