Studies of cholesterol´s influence on the phase transition of mixtures of diacetylenic and satured phospholipids model membranes

RUBIO MF; VIERA LI; ALONSO-ROMANOWSKI S

Baltimore, Maryland, EE.UU

Congreso; 43rd Annual Meeting of the Biophysical Society; 1999

Biophysical Society

Liposomes formed from polymerizable lipids retain many properties common toretain many properties common to conventional liposomes, but in addition exhibit some unusual features, such asin addition exhibit some unusual features, such as enhanced stability as a result of the polymeric nature of the bilayer. Polymerized liposomes are less permeable and show an increased resistance to precipitation, both properties are require in controlled drug delivery systems. Cholesterol incorporation both properties are require in controlled drug delivery systems. Cholesterol incorporation liposomes are less permeable and show an increased resistance to precipitation, both properties are require in controlled drug delivery systems. Cholesterol incorporation both properties are require in controlled drug delivery systems. Cholesterol incorporation of the bilayer. Polymerized liposomes are less permeable and show an increased resistance to precipitation, both properties are require in controlled drug delivery systems. Cholesterol incorporation both properties are require in controlled drug delivery systems. Cholesterol incorporation are less permeable and show an increased resistance to precipitation, both properties are require in controlled drug delivery systems. Cholesterol incorporationare require in controlled drug delivery systems. Cholesterol incorporation into conventional liposomes significantly reduces their permeability toconventional liposomes significantly reduces their permeability to entrapped solutes, as a result of cholesterol-induced condensation of the bilayer.as a result of cholesterol-induced condensation of the bilayer. Spectroscopic, spectrofluorometric and microscopic studies were carried out onand microscopic studies were carried out on ternary systems of model membranes. Mixtures of diacetylenic (C23id PC) and saturated short chain phospholipids (DMPC, DPPC, DSPC and DPhPC) in the saturated short chain phospholipids (DMPC, DPPC, DSPC and DPhPC) in the diacetylenic (C23id PC) and saturated short chain phospholipids (DMPC, DPPC, DSPC and DPhPC) in theDPhPC) in the presence of 20% mol cholesterol were used to prepare MLV and SUV. In this study20% mol cholesterol were used to prepare MLV and SUV. In this study we used the optical probe MC540 and uv-visible spectroscopy to measure phaseused the optical probe MC540 and uv-visible spectroscopy to measure phase transition temperatures. Experimental data show that the incorporation of 20%temperatures. Experimental data show that the incorporation of 20% mol cholesterol lowers and broadens the otherwise sharp phase transition temperature.the otherwise sharp phase transition temperature. The different systems are compare with their homologs after polimerization.are compare with their homologs after polimerization. Optical contrast phase microscopy was used to differentiate the liposomes from the tubular formation. The results presented in this study suggest a possible correlation between the area of the different absorption peaks in the gel and liquid between the area of the different absorption peaks in the gel and liquid the tubular formation. The results presented in this study suggest a possible correlation between the area of the different absorption peaks in the gel and liquid between the area of the different absorption peaks in the gel and liquid contrast phase microscopy was used to differentiate the liposomes from the tubular formation. The results presented in this study suggest a possible correlation between the area of the different absorption peaks in the gel and liquid between the area of the different absorption peaks in the gel and liquid The results presented in this study suggest a possible correlation between the area of the different absorption peaks in the gel and liquidarea of the different absorption peaks in the gel and liquid crystalline state and the length of the saturated phospholipids.state and the length of the saturated phospholipids.