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UBC Theses and Dissertations

Electrochemically controlled interaction of liposomes with a solid-supported octadecanol bilayer Musgrove, Amanda


Transmembrane proteins and ion channels are a major target for new drug development. Incorporating them into sensors requires a method to produce stable, easily modifiable solid-supported phospholipid bilayers. This thesis demonstrates a method for using potential control on the electrode to mediate liposome adsorption, allowing them to interact with a previously deposited octadecanol layer through potential-created defects. Compression isotherms and electrochemical measurements were used to establish the effect of the incorporation of a small amount of fluorescent dye on the octadecanol layers. Using these fluorescently-labelled octadecanol layers, electrochemical measurements both independently and coupled with in-situ fluorescence measurements were used to characterize the interaction of liposomes with these layers under potential control. It was found that application of moderate potentials - more negative than the onset of defect formation but less than that required for desorption of the layer - facilitated the effective incorporation of liposome material into the octadecanol bilayer. The length of time spent at the poration potential had little effect on the degree of liposome interaction with the adsorbed layer. The incorporation was seen as a change in the double-layer capacitance and the creation of small fluorescent structures in the layer after exposure to liposomes at the poration potential. A shift in the characteristic desorption potential was also seen with liposome incorporation. Atomic force microscopy coupled in-situ with electrochemical control was also used to investigate the interaction of liposomes with the adsorbed octadecanol layer. The structure of the adsorbed layer was observed and with liposomes present in solution, the creation of three-dimensional structures similar in nature to those seen by fluorescence was noted. The incorporation of liposomes into the octadecanol was shown to be easily controlled by application of an electrical potential, opening a path for a new method of producing supported lipid bilayers in-situ for biosensing applications.

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