A study of DPPC and DMPC monolayers at different temperatures using epifluorescence surface balance

Ibrahim, Akram Yousif (2000) A study of DPPC and DMPC monolayers at different temperatures using epifluorescence surface balance. Masters thesis, Memorial University of Newfoundland.

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    Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
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Abstract

In this study some modifications have been introduced to the existing Epifluorescence Surface Balance (EFSB). Those modifications are essential for working at different temperatures. Phospholipid researchers are interested in revealing the mysterious behavior of certain phospholipids such as Dipalmitoylphosphatidylcholine (DPPC) which is the major component of lung surfactant. Many published studies have presented the surface pressure - area per molecule isotherms of DPPC and Dimyristoylphosphatidylcholine (DMPC) at different temperatures. In this study isotherms of DPPC and DMPC in the temperature range from 14 °C to 42 °C and from 6 °C to 23.3°C respectively, have been constructed after modifications have been introduced. A good agreement between the published isotherms and the ones presented here is obtained. The isotherm technique has been found invaluable, but may be usefully complemented by other techniques for obtaining information about the phase behavior of lipid monolayers at the air/water interface. -- Unfortunately, there are not many published studies at higher temperatures in the field of visualization of the phospholipid monolayer domains. The problem of subphase condensation on the surface of the objective lens and other problems have prevented researchers from carrying out such studies. In this study the problem of the condensation has been minimized by introducing a technique of "Teflon Sleeve" heater. Some stimulating results are presented concerning the visualization of domains of DPPC at temperatures in the range from 18 °C to 35 °C. -- The study presented in this thesis can be useful to researchers who are interested in visualizing the domains of DPPC and monitoring their behavior at temperatures near to physiological temperature, which is 37 °C. -- The domains of DMPC also have been visualized at temperature of 5 °C. Unfortunately, the DMPC domains have not been recorded due to their small size. The limitation in the resolution of our recording system has prevented that recording. -- Fundamental literature about phospholipid monolayers - particularly DPPC and DMPC- is presented in chapters one and two. The experimental set-up of the EFSB is discussed in chapter three. The results, which have been obtained in this study, are discussed in chapter four.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/5797
Item ID: 5797
Additional Information: Bibliography: leaves 115-118.
Department(s): Science, Faculty of > Physics and Physical Oceanography
Date: 2000
Date Type: Submission
Library of Congress Subject Heading: Lipid membranes; Phospholipids; Monomolecular films

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