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Title: Investigations of tethered bilayer lipid membranes for their potential use in biosensing devices
Author: Vockenroth, Inga Kerstin
ISNI:       0000 0001 3548 8331
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2007
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Tethered bilayer lipid membranes (tBLMs) provide a model platform for the investigation ofvarious membrane related processes. They are especially suited to study the incorporation and function of ion channel proteins, where a high background resistance ofthe membrane is essential. In this study, the electrochemical sealing properties ofnew tBLMs are characterised and improved. Membranes of different compositions have been studied for their ability to host ion channels using Surface Plasmon Resonance Spectroscopy (SPR) and Electrochemical Impedance Spectroscopy (EIS). Several membrane proteins such as carriers, channels and pores were functionally incorporated. and investigated in different tBLM architectures. As a first test of the functionality of the membrane assembly the carrier valinomycin and the channel gramicidin were incorporated and their ion selectivity demonstrated with EIS. The transmembrane fragment M2 of the nicotinic acetylcholine receptor (nAChR) was embedded into a tBLM by fusion of proteoliposomes with different monolayers. The pore was selective for small monovalent cations, while bulky ions could not pass the membrane. The tBLMs provide a platfonn for the study of ion transport phenomena and ligand interactions of channels such as the nAChR, as the presented method should be generally applicable to other membrane proteins. Incorporation of a-haemolysin, a toxin that leads to lysis of cells by formation of large pores in the cell m,e. mbrane, was achieved. The tBLM provides a fluidity that allows incorporating the pores, while at the same time providing a submembrane space between the solid support and the bilayer. This offers the ability to measure ion currents through the incorporated channels. A membrane architecture specially suited for an enhanced functionality ofthe pores was designed and characterised. Downsizing the membrane area on Jl-electrodes gave gigaohmic membrane resistances, showing sealing properties comparable to BLMs. This gigaseal allowed for highly f sensitive measurements ofcurrents through incorporated a-haemolysin pores. With this system, a biosensor with modified biological receptors as actual sensing units is feasible, whereas the high stability opens the perspective of long-term experiments and continuous monitoring. Thus, a major step towards the use of proteins as stochastic sensing elements in prospective biosensor applications has been accomplished.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available