UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2005 Meeting


Section: Electricity and Biophysics


Title:
Supported Chlorophyll-lipid Membranes


Authors:
Adrian Teodor Enache, Laura Tugulea


Affiliation:
Department of Electricity and Biophysics,

Faculty of Physics -University of Bucharest, Romania


E-mail


Keywords:


Abstract:
Supported lipid bilayers (SLB) could be obtained by the deposition of liposomes on solid surfaces using different techniques. This new approach provides access to basic aspects of membrane biophysics and molecular ordering and may constitute a strategy for developing different applications. Chlorophyll a (Chla ) has the ability to act as sensor for specific molecular interactions in the liposome bilayer. The objective of the present work was to obtain stable supported chl-lipid membranes and to characterize the structures by using Chla as marker and molecular sensor. Multilamellar and small unilamellar vesicles with Chla were prepared. The mechanical dispersion method was used to obtain multilamellar vesicles and sonication for further obtaining unilamellar vesicles. The liposomes were prepared using Chl a/lipid films with specific molar ratio (1/10 and 1/100) and different lipids (lecithin, DMPC, DPPC, DOPC). Chla was freshly extracted from spinach leaves and separated by chromatography. Vitamin E (a-tocopherol) was used as an antioxidant (scavenger for oxygen free radicals, lipid peroxide radicals and singlet oxygen) and as a membrane stabiliser. Spectral criteria were developed in order to monitor the size of liposomes, the oxidation state of the components of the Chla-liposomes, both in suspension and on support. By using spectral criteria, the effect of a-tocopherol as a suitable antioxidant agent was demonstrated. Adsorption of Chla-liposomes was used for obtaining thin films on semi-transparent electrodes. The obtained supported Chla-lipid membranes were monitored by spectral and microscopic methods. The nature of lipids, the molar ratio Chla/lipid in the liposomes and the presence of a-tocopherol proved to be key actors for the stability of the obtained Chl-lipid membranes.