Examing the Lyotropic Liquid Crystalline Phases
of a Physiological Mixture:
This project is an investigation of the lyotropic liquid crystalline phases of a physiological system composed of three biological lipids in water. Lyotropic liquid crystals are composed of two or more components and enter phase transitions when the concentration of one or more of these components is altered, or the temperature of the system is changed, or a combination of both conditions occurs. The components used in this study represent the main components of human bile, and the experimental procedures were carried out at 37 degrees C, body temperature. As the ratio of the components was changed, different lyotropic phases were observed, including multilamellar vesicles and micelles. These phases had been previously determined by the use of HNMR data. Techniques used in this study include optical microscopy, dynamic light scattering, and X-ray scattering. The data that were collected confirmed the presence of phase transitions when the ratio of lipids was altered. The microscopic data gave insight into the progression of phase transitions, and also gave information concerning the macroscopic physical structure of each phase. The dynamic light scattering data indicate that a variety of particle sizes exist in equilibrium during the micellar phase. In addition, the x-ray scattering data yielded information concerning the symmetry of different phases, and also gave information concerning spacing between different layers of molecules for various phases. It was also discovered that, in the presence of a relatively small magnetic field (1-2 kG), some molecular alignment occurred in certain phases.
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