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It is the purpose of this thesis to report further studies on the vesicles appearing in phage lysates of Escherichia coli, phage attachment to these vesicles, and the presence of similar vesicles in lysozyme and penicillin lysed cultures.

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published_or_final_version / Anatomy / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 1994. / Includes bibliographical references (leaves 129-157).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 304-311).

Dielectrophoresis and electrorotation are receiving increasing attention as useful phenomena for the characterisation and physical manipulation of cells. The primarily concern of this investigation was to determine whether these techniques can interpret accurately the dielectric properties of biological cells with an appropriate dielectric shell model. In this study, synthetic vesicles have been used as the testing samples in electrorotation experiments to verify the reliability of these techniques. By using the electrorotation technique with the dielectric shell models, dielectric properties of vesicles could be analysed very accurately and the results were in agreements with the observed morphology and membrane properties. The physical structure of the vesicles varied from a simple one such as unilamellar vesicle, to a more complex structure such as the oligolamellar and multilamellar form. The morphology and membrane structure of the vesicles were also characterised by fluorescence microscopy, flow cytometry and electron spin resonance using spin probes. This allowed this validification of the application of the dielectric shell theory for analysis of simple cellular systems. The second objective of this work was to extend the potential used of the electrorotation technique, and not only for the analysis of cellular systems. Electrorotation was also performed on single stranded DNA oligonucleotides, covalently bound onto the surface of microscopic-sized latex beads. Different types of the DNA oligonucleotides exhibited different electrorotation responses according to their different base sequences. This has shown that the electrorotation technique can be used as an analytic tool to identify different sequences of DNA oligonucleotide.

The specific interaction between saccharide molecules and saccharide-binding proteins, lectins, can be exploited in order to actively target nanostructures to specific cell types for diagnostic or therapeutic purposes. However, the conjugation of saccharides to nanostructures can be complex, leading to a lack of versatility in the functionalities that can be achieved, or poorly characterized and therefore potentially inconsistent. Herein is reported a new procedure by which novel saccharide-containing molecules, for the functionalization of nanostructures, could be synthesized rapidly and with good yields. The synthesis was found to be versatile, providing coating molecules for magnetite nanoparticles and phospholipid vesicles from a number of different hydrazides and reducing sugars. The stability of the synthesized coating molecules was assessed, both in aqueous solution and when bound to the surface of a magnetite nanoparticle, and found to be satisfactory for cell culture purposes. The availability of the saccharide units for lectin binding was confirmed using a Quartz crystal microbalance (QCM-D) in addition to a number of assays. Finally, microscopy techniques were used to study the interactions between saccharide-functionalized magnetite nanoparticles and two cell types, fibroblasts (3T3) and hepatocytes (HepG2).This work demonstrated the ability of saccharide coatings to improve the uptake of nanostructures in a cell culture environment and highlighted the potential cell manipulation application of saccharide-coated magnetite nanoparticles.

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