title: The modified fluorescence based vesicle fluctuation spectroscopy technique for determination of lipid bilayer bending properties.
abstract: Lipid bilayer is the main constitutive element of biological membrane, which confines intracellular space. The mechanical properties of biological membranes may be characterized by various parameters including membrane stiffness or membrane bending rigidity, which can be measured using flicker noise spectroscopy. The flicker noise spectroscopy exploits the spontaneous thermal undulations of the membrane. The method is based on the quantitative analysis of a series of microscopic images captured during thermal membrane fluctuations. Thus, measured bending rigidity coefficient depends on the image quality as well as the selection of computational tools for image processing and mathematical model used. In this work scanning and spinning disc confocal microscopies were used to visualize fluctuating membranes of giant unilamellar vesicles. The bending rigidity coefficient was calculated for different acquisition modes, using different fluorescent probes and different image processing methods. It was shown that both imaging approaches gave similar bending coefficient values regardless of acquisition time. Using the developed methodology the effect of fluorescent probe type and aqueous phase composition on the value of the membrane bending rigidity coefficient was measured. Specifically it was found that the bending rigidity coefficient of DOPC bilayer in water is smaller than that determined for POPC membrane. It has been found that the POPC and DOPC bending rigidities coefficient in sucrose solution was lower than that in water. Fluorescence imaging makes possible the quantitative analysis of membrane mechanical properties of inhomogeneous membrane.
authors.affiliation: Laboratory for Biophysics of Lipid Aggregates, Department of Biomedical Engineering, Wrocław University of Technology, 50-377 Wrocław, Pl. Grunwaldzki 13, Poland; Lipid Systems sp. z. o. o., ul. Duńska 9, 54-427 Wrocław, Poland. Electronic address: Dominik.Drabik@pwr.edu.pl.
authors.forename: Dominik
authors.initials: D
authors.lastname: Drabik
authors.affiliation: Laboratory for Biophysics of Lipid Aggregates, Department of Biomedical Engineering, Wrocław University of Technology, 50-377 Wrocław, Pl. Grunwaldzki 13, Poland; Lipid Systems sp. z. o. o., ul. Duńska 9, 54-427 Wrocław, Poland.
authors.forename: Magda
authors.initials: M
authors.lastname: Przybyło
authors.affiliation: Wroclaw Research Centre EIT+, ul Stabłowicka 147, 54-066 Wrocław, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Chodaczek
authors.affiliation: Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia.
authors.forename: Aleš
authors.initials: A
authors.lastname: Iglič
authors.affiliation: Laboratory for Biophysics of Lipid Aggregates, Department of Biomedical Engineering, Wrocław University of Technology, 50-377 Wrocław, Pl. Grunwaldzki 13, Poland; Lipid Systems sp. z. o. o., ul. Duńska 9, 54-427 Wrocław, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Langner
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; C017251:1,2-oleoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: Bending elasticity; Fluorescence microscopy; Membrane mechanics; Vesicle fluctuation analysis