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UBC Theses and Dissertations

Cell partition in aqueous polymer two phase systems Van Alstine, James Melvin


Experimental studies of the partition of cells and dimyristoyl phosphatidylcholine (DMPC) liposomes in aqueous polymer two phase systems containing dextran T500 and poly-(ethylene glycol) (PEG) 8000 have been carried out. Work has been completed in five areas: (1) PEG 8000-1-¹⁴C-palmitate fatty acid ester, synthesized via a procedure involving oxalyl chloride activation of free 1- ¹⁴C-palmitic acid, was used in the development of a method to chemically assay PEG esterification and a column chromatographic procedure for the purification of PEG-alkyl derivatives. (2) A series of dextran/PEG two phase systems compounded with various amounts of sodium phosphate, pH 7.2 buffer and made isotonic with sodium chloride were developed. These systems were shown to exhibit electrostatic bulk phase potentials whose magnitude decreased with increasing sodium chloride concentration. (3) The PEG-fatty acid ester induced partition of DMPC small unilamellar liposomes was shown to increase in association with lipid gel to liquid-crystalline phase transitions induced by an increase in ambient experimental temperature or exposure of the liposomes to free linoleic acid. (4) The effects of manipulation of a wide range of experimental variables on the partition of normal human erthrocytes have been noted. The variables chosen included; system polmer lot, concentration and purity, system salt composition, PEG-fatty acid ester type, concentration and purity, cell type and concentration, cell fixation with various aldehyde fixatives and cell exposure to Vibrio cholera neuraminidase. Under appropriate conditions the logarithm of the partition coefficient K (equal to the ratio of the number of cells partitioning into the upper phase to the number of cells not partitioning into the upper phase) has been shown to be directly proportional to system electrostatic interfacial potential, interfacial bulk phase tension, and system PEG-fatty acid ester concentration. Furthermore, it has been shown that PEG-fatty acid ester induced cell partition is hydrophobic in nature and appears to be dependant on ester-cell rather than ester-system interactions. (5) Erythrocytes from patients with multiple sclerosis have been demonstrated to exhibit less upper phase affinity than normal subjects' erythrocytes in a variety of two phase systems.

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