Lecithin Organogels Used as Bioactive Compounds Carriers. A Microdomain Properties Investigation

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• 作者：Spyridon Avramiotis ; Vassiliki Papadimitriou ; Elina Hatzara ; Vlasoula Bekiari ; Panagiotis Lianos ; Aristotelis Xenakis
• 刊名：Langmuir
• 出版年：2007
• 出版时间：April 10, 2007
• 年：2007
• 卷：23
• 期：8
• 页码：4438 - 4447
• 全文大小：129K
• 年卷期：v.23,no.8(April 10, 2007)
• ISSN：1520-5827

文摘

Organogels were obtained by adding small amounts of water to a solution of lecithin in organic solvents. Eitherisooctane or isopropyl palmitate and isopropyl myristate were used as the continuous organic phase of the gels. EPRspectroscopy using both DSA membrane-sensitive and lipophilic spin probes was applied to define the dynamicstructure of the surfactant monolayer and the continuous oil phase of lecithin organogels. It was found that byincreasing the water quantity, an increase of the polar head area per lecithin molecule was induced, and as a consequencethe total interface expanded. It was found that the use of esters as organic solvents induced a decrease of the size ofthe dispersed structures. The interconnection of the aqueous microdomains and their dynamics were monitored byboth static and time-resolved fluorescence quenching spectroscopy using Ru(bipy)₃²⁺ as fluorophore and Fe(CN)₆^3-as quencher. It was found that the rates of inter- and/or intra-micellar exchange of water molecules were very slowbecause they appeared quite immobilized close to the lecithin polar heads. According to the results of the dynamicstudies, appropriate organogels were formulated and used to incorporate model bioactive compounds with medicinalor cosmetic interest such as caffeine and theophylline. When these systems were tested for trans-membrane diffusion,they showed a 24 h permeation of 20% and 35%, respectively.