A Study of Cholesterol Effect on Ion-Pair Amphiphile Vesicular Bilayer Rigidity by Using Fluorescence Polarization Technique

Autor: Chia-YuCheng, 鄭嘉瑜
Rok vydání: 2019
Druh dokumentu: 學位論文 ; thesis
Popis: 107
Due to their abundant sources, low cost, high chemical stability and molecular designability, lipid-like ion-pair amphipliles (IPAs, also known as catanionic surfactants) have emerged as attractive materials to prepare potential vesicular carriers in drug and gene delivery. In this work, cholesterol (CHOL) effect on bilayer rigidity of decyltrimethylammonium-dodecylsulfate, DeTMA-DS), decyltrimethylammonium-tetradecylsulfate (DeTMA-TS), and dodecyltrimethylammonium-dodecylsulfate (DTMA-DS) catanionic vesicles and dipalmitoylphosphatidylcholine (DPPC) liposomes were systematically studied by using fluorescence polarization technique. Vesicle stability and physical properties of them as the consequences of CHOL addition were also investigated. The experimental fluorescence anisotropy (FA) thermograms showed that fluorescence anisotropies of catanionic vesicle bilayers were monotonically increased with increasing of CHOL concentration. This effect of CHOL, however, is quite different from that on liposomal bilayers in which CHOL exhibited disordering and condensing effects when the temperatures were lower and higher, respectively, than the main phase transition temperature (Tm) of lipid. The different results are due to the fact that catanionic vesicles with thinner bilayer thickness exhibited much lower bilayer rigidity at temperatures lower than Tm as compared with those of liposomes. Under these conditions, there is no role for the disordering effect of CHOL to play on the ordering of bilayers. Furthermore, vesicle stability and size of vesicles fabricated by the process through the formation of thin films were found to be significantly enhanced with the addition of CHOL and reasonably explained by the increment of bilayer rigidity. The results achieved in this work is beneficial to applications of catanionic vesicles as carriers in drug and gene delivery.
Databáze: Networked Digital Library of Theses & Dissertations
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