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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:56 |
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Conference: Bucharest University Faculty of Physics 2014 Meeting
Section: Biophysics; Medical Physics
Title:
Log-normal deconvolution of Laurdan fluorescencespectra - A tool to assess lipid membrane fluidity
Authors:
B. ZORILA(1,2), Mihaela BACALUM(1), M. RADU(1)
Affiliation:
1) Department of Life and Environmental Physics, “Horia Hulubei” National Institute of Physics and Nuclear Engineering, Magurele, Romania
2) Department of Electricity, Solid State and Biophysics, Faculty of Physics, University of Bucharest, Magurele, Romania
E-mail
bzorila@nipne.ro
Keywords:
Laurdan fluorescence, generalised polarization, Gauss vs. log-normal deconvolution, lipid membrane fluidity, phospholipid phase transition
Abstract:
Deconvolution of complex steady-state fluorescence spectra is a key subject in analytical fluorescence spectroscopy. The shape of the spectra is generated by the presence in the analysed solution of a mixture of several fluorophores or by a single fluorophore found in different excited states. The spectra shape of most of the fluorophores is asymmetric, even in a homogenous solution, where only one excited state is presumed to be present. Due to this, fluorescence spectra can be analyzed much better by a log-normal (LN) distribution than by a Gaussian one.
Laurdan is a membrane fluorescent probe who has the advantage of detecting changes in bilayer phase properties. Due his hydrophobicity (12-carbon aliphatic tail), Laurdan molecule has been reported to be located at the hydrophilic-hydrophobic interface of the bilayer. Laurdan typical red-shift (~50 nm) is observed during the phospholipid phase transition, and is originating from the probe sensitivity to its environment polarity.In this study we made a comparison between Gauss and LN deconvolution of fluorescence spectra of Laurdan, inserted in large unilamellar vesicles prepared from different types of lipids: 13:0 PC, DMPC, DPPC and DSPC. The relative areas of the elementary peaks were used to obtain a parameter similar to GP, the difference of relative areas: ∆Sr = SrB – SrG. ∆Sr depends, due to the peak areas, on the fractions of emitting molecules found in bilayer and proved to be more sensitive than GP assessing lipid membrane fluidity.We found that the results obtained after analysing the data are consistent with those reported in literature and confirming the existence of two populations of fluorophores who emit at different wavelengths.
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