Cationic cage-like complexes formed by DC-cholesterol, Quil-A, and phospholipid

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This study describes the formation of cationic, cage-like complexes which have a structure similar to classic anionic ISCOMs. In order to prepare these complexes cholesterol, a major component of classic ISCOM formulations, was substituted with a cationic derivative, 3beta-[N-(N',N'-dimethylaminoethane)-carbamoyl]-cholesterol (DC-CHOL). Colloidal dispersions with varying compositions of DC-CHOL, phosphatidylcholine, and Quil-A, which is a mixture of anionic triterpene saponins, were prepared by the lipid-film hydration method and characterised by transmission electron microscopy and laser Doppler electrophoresis. The colloidal structures obtained are presented in pseudo-ternary phase diagrams with two buffer systems as the pseudo-component. It was found that the formation of cationic, cage-like particles is highly depending on the formulation buffer. With TRIS buffered saline (TBS) pH 7.4, cage-like particles formed at compositions with high proportions of DC-CHOL and had a strongly positive zeta-potential. These could be purified by differential centrifugation. With phosphate buffered saline pH 7.4, the formation of cage-like particles was much reduced. It was shown that the formation of cage-like particles with a positive charge depended on suitable concentrations of TRIS in the hydration buffer.
Original languageEnglish
JournalJournal of Pharmaceutical Sciences
Issue number8
Pages (from-to)1794-807
Number of pages14
Publication statusPublished - 2005
Externally publishedYes

    Research areas

  • Adjuvants, Immunologic, Buffers, Cations, Chemistry, Pharmaceutical, Cholesterol, Micelles, Microscopy, Electron, Particle Size, Phospholipids, Saponins

ID: 40357638