Effect of Temperature on Release Behavior of Charged Catanionic Vesicles
| Autor: | Jhen-yi Hong, 洪振益 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 The phospholipid PL-90 and ion-pair amphiphiles (HTMA-DS, TTMA-DS, and DTMA-DS), which are double-chained surfactants prepared through precipitation by mixing cationic and anionic single-chained surfactants, were used as the main materials to form liposomes and catanionic vesicles, respectively, by a semispontaneous process at 70 ℃. The experimental results showed that this method is not applicable to the preparation of liposome even by the addition of cholesterol. On the other hand, positively and negatively charged catanionic vesicles can be successfully prepared by using HTMA-DS and DTMA-DS with the addition of cholesterol and various amounts of single-chained ionic surfactants. Effects of composition on the size, zeta-potential, and physical stability of the ensuring catanionic vesicles in water and buffer solutions were systematically studied. Furthermore, the encapsulation and release behavior of the ensuring catanionic vesicles were also investigated by using 5(6) -carboxyfluorescein (CF) as fluorescent probe molecules. The experimental results showed that only negatively charged catanionic vesicles are able to encapsulate CF molecules. However, CF molecules were unable to be encapsulated by positively charged catanionic vesicle. This is due to the precipitation resulted from the electrostatic intertation between the oppositely charged CF molecules and catanionic vesicles. Furthermore, negatively charged HTMA-DS catanionic vesicles can’t survive the size exclusion chromatography during separation process. On the evidence of zeta-potential and fluorescence measurements, this may be due to the SDS molecules without incorporation intact between HTMA-DS molecules in the bilayer structure of vesicles. Encapsulation efficiencies around 0.65~0.7% were determined and effect of temperature on release rate was studied for negatively charged DTMA-DS catanionic vesicles. The release rates were found to increase with the increase of temperature and there existed a drastic change of release rate around 50 ℃. This may find their potential use in temperature-controlled drug release by using catanionic vesicle as carriers. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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