title: Assembly of a model hydrophobic drug into cationic bilayer fragments.
abstract: Our previous work has shown that dioctadecyldimethylammonium bromide (DODAB) bilayer fragments (BF) presented antimicrobial activity, solubilized fungicides, e.g., amphotericin B and miconazole (MCZ), stabilized hydrophobic drug particles and were effective in vivo. Here, the interaction between MCZ and DODAB BF is evaluated from determination of BF loading capacity and effects of drug-to-lipid molar proportion (MP) on particle size, zeta potential and gel-to-liquid-crystalline phase transition T(m). DODAB BF solubilized MCZ over a range of MP. BF loading capacity was 0.5 mM MCZ at 5 mM DODAB. Above this limit, the drug aggregated in the dispersion. At pH 6.3, BF zeta potentials decreased with MP, suggesting insertion of deprotonated drug into the bilayer. MCZ optical spectra in BF were similar to those in best organic solvent, confirming drug solubilization. At MP 1:10, BF T(m) remained unchanged, suggesting drug capture at BF hydrophobic edges. At MP 1:10, T(m) decreased, showing MCZ insertion into DODAB bilayer. However, drug was expelled from the bilayer core upon lowering temperature. Minimal fungicidal concentrations against C. albicans were synergically reduced by 10 times for drug/BF.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CP 26077, Avenida Lineu Prestes 748, Butantã, CEP 05513-970, São Paulo, Brazil.
authors.forename: Débora B
authors.initials: DB
authors.lastname: Vieira
authors.forename: Luis F
authors.initials: LF
authors.lastname: Pacheco
authors.forename: Ana M
authors.initials: AM
authors.lastname: Carmona-Ribeiro
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D002176:Candida albicans / Q000737:chemistry / Q000187:drug effects; D002412:Cations / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D008825:Miconazole / Q000737:chemistry* / Q000494:pharmacology; D008954:Models, Biological; D008956:Models, Chemical; D015394:Molecular Structure; D044367:Phase Transition; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012995:Solubility; D013057:Spectrum Analysis
chemical_list: D000935:Antifungal Agents; D002412:Cations; D008051:Lipid Bilayers; D000644:Quaternary Ammonium Compounds; C015831:dimethyldioctadecylammonium; D008825:Miconazole