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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:18 |
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Conference: Bucharest University Faculty of Physics 2003 Meeting
Section: Electricity and Biophysics
Title:
Chlorophyll a in Liposomes- Spectral Studies
Authors:
Adriana Sumanaru, Marcela Barbīnta-Patrascu, Violeta Ciofu, Laura Tugulea
Affiliation:
Faculty of Physics- University of Bucharest
E-mail
Keywords:
Abstract:
Liposomes with chlorophylla (Chla) are model membranes providing a hydrophobic environment for Chla. The objective of our work was to prove that the spectral features of Chla allow its use as sensor for physical properties of liposomes (size, shape, molecular dynamics).
Small unilamellar and multilamellar vesicles with Chla were prepared. The mechanical dispersion method was used to obtain multilamellar vesicles. Unilamellar liposomes were obtained from multilamellar vesicles by mechanical dispersion (Vortex) and bath sonication for 30-40 minutes. The liposomes were prepared using Chla/lipid films with specific molar ratio (1/100) and different lipids (DMPC, DOPC, soybean lecithine). Chla was extracted from fresh spinach leaves and separated by chromatography. The films were dispersed in buffer solutions of different pH (7.0 - 7.1). Ultracentrifugation (100,000 g) was used to obtain homogenous size liposomes population. Chl a and lipid modifications in the bilayer were monitored by absorption and emission spectroscopy.
A 1/lambda4 dependence of the baseline was observed in VIS absorption spectra of liposomes with Chla, suggesting that the size of the vesicles are roughly in the size range of the wavelength of the measuring light. Spectral criteria were developed in order to monitor the size of liposomes, the oxidation state of the components and for studying the effect of different chemical (oxidants, drugs) and physical agents (MW, ultrasounds) on liposomes with Chla.
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