Influence of Cyclosporine A on molecular interactions in lyotropic reverse hexagonal liquid crystals

Paul Ben Ishai, Dima Libster, Abraham Aserin, Nissim Garti, Yuri Feldman

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13 Scopus citations

Abstract

We present a dielectric study of HII mesophases (HII) based on a GMO/tricaprylin/phosphatidylcholine/water system seeded with the peptide Cyclosporine A (CSA). The study covers a frequency range 0.01 Hz to 1 MHz and a temperature range of 293 to 319 K, with a 3 K temperature step. Three dielectric relaxation processes are observed and discussed. This picture is further elucidated by comparison with a dielectric study of the empty H II mesophase system, previously published, where the same three processes were involved. A complex picture emerges whereby the CSA is intercalated between the surfactant tails yet protrudes into the interface as well. Whereas the CSA remains hydrophobic, it still influences the relaxation behavior of the GMO head and counterion movement along the interface in a nontrivial manner. The third dipolar species, the tricaprylin molecule, is also influenced by the presence of CSA. A critical temperature T0 = 307 K is recognized and identified as the dehydration temperature of the surfactant heads. This induces a conformal transition in the CSA, drastically changing its effect on the three dielectric processes evident in the raw data. The implications of this behavior are discussed in detail.

Original languageEnglish
Pages (from-to)12785-12791
Number of pages7
JournalJournal of Physical Chemistry B
Volume114
Issue number40
DOIs
StatePublished - 14 Oct 2010
Externally publishedYes

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