| Abstract |
It is well known that all cells are surrounded by a cell membrane that consists of a lipid bilayer. For the study of membrane interactions in vitro, it is necessary to form model membranes. The best model membrane systems comprise supported lipid bilayers (SLBs). The SLBs are formed on polymer or glass surfaces by fusion and rupture of vesicles which are hydrated compartments of lipid bilayers. For this work an acoustic Love wave biosensor was used for the study of SLB formation. The initial requirement was the formation of a homogeneous, smooth and hydrophilic surface on the acoustic device. Firstly, the biosensors' surface was coated with a thin film of the polymer poly(dimethyl siloxane) (PDMS). The hydrophobic surface of the PDMS was made hydrophilic with plasma etching. Atomic force microscopy was employed to demonstrate that the best etching conditions were in the presence of air. The formation of SLBs on this surface was monitored in real time, through the change of phase and amplitude of the acoustic wave. The existence of the SLBs was confirmed with the fluorescence microscope using the technique of fluorescence recovery after photobleaching. Through the analysis of the fluorescence microscopy images, the lateral diffusion constant D was calculated for the fluorescently labelled phosphatidylcholine (PC) in bilayers with different concentrations of cholesterol. The results showed that the formation of SLBs leads to a 5,3 ± 0,4 deg drop in the phase of the acoustic wave on the device with an operation frequency of 155 MHz and that the drop in phase was bigger when a vesicle layer was formed. In addition, the lateral diffusion constant of the fluorescently labelled PC was found to be 0,46*10-8 cm2/s. As expected, the increase of the concentration of cholesterol was associated with a decrease of the lateral diffusion constant.
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Μελέτη σχηματισμού υποστηριζόμενης λιπιδικής διπλοστιβάδας με χρήση ακουστικού βιοαισθητήρα και μικροσκοπίας φθορισμού
