Martin Hof "Hydration, mobility, aggregation, and nanodomain formation in model membranes studied by fluorescence"

Fluorescence is certainly a widely used spectroscopic technique in biological membrane sciences. One reason for that is that fluorescence can be used in all kind of model systems, like monolayers, supported lipid bilayers, black lipid membranes, or differently sized unilamellar vesicles, as well as in living cells. Using a fluorescent reporter molecule one can gain -depending on the specific techniques chosen- information on location, dynamics and polarity of the labeled system of interest. Although within recent years super-resolution microscopy techniques have moved in the focus of interest, I believe that the combination of “conservative” techniques still can provide valuable information on specific question in lipid membrane biophysics. Specifically in this lecture the time-dependent fluorescence shift approach[1], different variants of fluorescence fluctuation spectroscopy[2], and a Monte Carlo / FRET approach will be discussed[3]. Choosing from those techniques three different membrane topics will be addressed: 1) The influence of different monovalent ions („Hofmeister“-series)[4-7]. 2) The impact of truncated oxidized phospholipids[8-10]. 3) Dynamics and size of lipid nanodomains in model membranes[11].

(1)    Jurkiewicz, P.; et al.. Lipid hydration and mobility: An interplay between solvent relaxation experiments and molecular dynamic simulations.  Biochimie   2012, 94, 26-32.
(2)    Macháň, R.; Hof, M. Lipid diffusion in planar membranes investigated by fluorescence correlation spectroscopy. Biochimica Et Biophysica Acta-Biomembranes 2010, 1798, 1377-1391;
(3)    Šachl, R.; et al.. Limitations of Electronic Energy Transfer in Lipid Nanodomain Size Estimation. 2011, Biophys. J., 101, L60-L62.
(4)    Vácha, R et al. Effects of alkali cations and halide anions on the DOPC lipid membrane. Journal of Physical Chemistry A.  113,  26 2009,  7235-7243
(5)    Vácha, R.; et al.. Mechanism of Interaction of Monovalent Ions with Phosphatidylcholine Lipid Membranes. Journal of Physical Chemistry B 2010, 114, 9504-9509;
(6)    Jurkiewicz, P et al.. Structure, Dynamics, and Hydration of POPC/POPS Bilayers Suspended in NaCl, KCl, and CsCl Solutions. 2012, BBA - Biomembranes, 1818, 609-616,
(7)    Pokorná, Š et al.. Interactions of monovalent salts with cationic lipid bilayers. Faraday Discussions.  160,  2013 (2013),  341-358.
(8)    Beranova, L et al.. Oxidation Changes Physical Properties of Phospholipid Bilayers: Fluorescence Spectroscopy and Molecular Simulations Langmuir 2010, 26, 6140-6144
(9)    Volinsky, R.; et al.Oxidised Phosphatidylcholones reconstitute phospholipid “scramblase” activity in liposomes. Biophysical Journal, 2011,  101, 6, 1376-1384
(10)    Jurkiewicz, P.; et al.. Biophysics of lipid bilayers containing oxidatively modified phospholipids: Insights from fluorescence and EPR experiments and from MD simulations. 2012, BBA Biomembranes 1818, 10, 2388-2402
(11)    Štefl, M.; et al. Dynamics and Size of Cross-Linking-Induced Lipid Nanodomains in Model Membranes. 2012, Biophysical Journal 102, 9, 2104-2113.