Modification of Membrane Surfaces with Carbohydrates: An Approach for Stabilization During Freezing and Drying

Citation

Goodrich, Raymond Paul, Jr. (1990) Modification of Membrane Surfaces with Carbohydrates: An Approach for Stabilization During Freezing and Drying. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ff9e-th51. https://resolver.caltech.edu/CaltechETD:etd-06072007-091301

Abstract

A new class of molecules possessing amphipathic character was prepared. These compounds possessed a hydrophobic region capable of intercalation into a lipid bilayer, a hydrophilic linker group capable of extending beyond the surface of a membrane, and a carbohydrate attached at the end of this linker group. These features of this class of compounds permitted their direct incorporation into vesicle formulations and hence the direct examination of interactions occuring in the dry state between carbohydrates and lipid groups in such vesicle membrane systems.

Samples of treated vesicle preparations were subjected to freezing and thawing as well as to direct dehydration via lyophilization. Under these conditions, the stability and integrity of the membrane was examined via several spectroscopic techniques.

Through these studies of systems in which a carbohydrate is directly bound to a membrane surface, it was possible to determine a defined ratio, independent of solution and concentration effects, at which carbohydrates can afford protection to dehydrated membranes. In addition, the interactions responsible for conferring the protection were determined. It was found that direct intercalation of the carbohydrates into a membrane interface preserves the membrane structure and organization that is normally observed in the presence of water. This behavior prevents the phase transitions, lipid phase separations, and fusion phenomena that normally compromise dehydrated membrane systems. This phenomena is directly related to the amount of carbohydrate that is present and the structure of the carbohydrate that is used. These results indicate that the partitioning behavior of the carbohydrates at the interface is of prime importance in determining the effectiveness in this regard.

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