Liposome adsorption to Candida albicans

The adsorption of anionic and cationic liposomes to the yeast form of the fungal cell Candida albicans in the stationary phase has been studied as a function of liposome composition-and concentration in phosphate-buffered saline (PBS) at pH 7.4. For liposomes of composition dipalmitoylphosphatidylcholine-phosphatidylinositol (DPPC-PI) it has been found that there is an optimum composition for adsorption for liposomes containing 18 mol% PI. Adsorption studies as a function of liposome concentration give Langmuir-type isotherms for liposomes of composition DPPC-PI, DPPC-cholesterol-stearylamine and DPPC-cholesterol-dimethyldioctadecylammonium bromide from which saturation values of liposomes adsorbed per cell and the association constants could be derived. The saturation values are consistent with the adsorption of a monolayer, though not necessarily close-packed, on the cell surface. The Gibbs energies of adsorption lie in a range -12 to -19 kJ mol(-1). The interaction between the cells of DPPC-PI liposomes is probably dominated by H-bonding between the polyhydroxy head group of PI and the oligosaccharides in the cell surface whereas for the cationic liposomes the interactions are predominantly ionic. (C) 1997 Elsevier Science B.V.