Interaction between cationic bilayers and Candida albicans cells

Abstract

The high-affinity adsorption of a cationic dioctadecyldimethylammonium bromide (DODAB) bilayer to the yeast form of the fungal cell Candida albicans was studied as a function of DODAB dispersion method, DODAB concentration and cell number density (n) in pure water. As previously observed for bacteria, the number of liposomes adsorbed per cell decreased as a function of n, possibly owing to increased cell aggregation and reduction of the total cell area with n. The DODAB limiting adsorption was 1.9 × 10⁹ and 9.5 × 10⁸ molecules per cell for bilayer fragments and large vesicles, respectively, in water solution; the extraattractive hydrophobic interaction between hydrophobic regions of biomolecules and hydrophobic borders of bilayer fragments possibly accounting for this result. Furthermore, at 1 mM cationic lipid or surfactant, the percentage cell phosphate leakage induced by bilayer fragments, large vesicles or cetyltrimethylammonium bromide micelles was small, about 4–10%, and was consistent with previously published data on the absence of bacterial cell lysis. Electrophoretic mobilities for cells in the presence of both DODAB dispersions were consistent with desorption of large vesicles from cells; this desorption was absent for the bilayer fragments.

Acknowledgments: Financial support from FAPESP and CNPq is gratefully acknowledged. L.F.P. thanks CAPES for a PhD fellowship. D.B.V. and F.M.C. were recipients of undergraduate FAPESP fellowships.