PARENT SESSION
Posters P5D Emerging techniques and systems. Abstracts (731-741)

Supported chlorophyll- lipid membranes for biotechnological applications. Laura Tugulea^*,, Marcela Barbinta-Patrascu,

ABSTRACT- The deposition of liposomes on solid surfaces, by different techniques, conducted to a new approach: supported lipid bilayers (SLB). This new approach provides access to basic aspects of membrane biophysics and molecular ordering and may constitute a strategy for developing biotechnological applications. Our former researches on liposomes with Chla provided evidence for the ability of Chla to act as sensor for specific molecular interactions in the liposome bilayer. Also we developed photoelectrochemical devices using Chla species absorbing at 740 nm. The objective of the present work was to obtain supported chl-lipid membranes and to characterize the structure by using Chla as a marker and molecular sensor. Small unilamellar and multilamellar 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 (DMPC, DPPC, DOPC). Chla was freshly extracted from spinach leaves and separated by chromatography. Vitamin E was used as an antioxidant (scavenger for oxygen free radicals, lipid peroxide radicals and singlet oxygen) and as a membrane stabiliser (influencing the membrane lipid organization and restricting the molecular mobility). 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 vitamin E as a suitable antioxidant agent was demonstrated. Adsorption and electrodeposition of Chla-liposomes were used for obtaining thin films on semi-transparent electrodes. The obtained supported Chla-lipid membranes were monitored both by spectral and electrochemical methods. The nature of lipids, the molar ratio Chla/lipid in the liposomes and the presence of vitamin E proved to be key actors for the stability of the obtained Chl-lipid membranes.

KEY WORDS: liposome, Chlorophyll a, supported lipid bilayers, photoelectrochemistry