title: Tuning membrane thickness fluctuations in model lipid bilayers.
abstract: Membrane thickness fluctuations have been associated with a variety of critical membrane phenomena, such as cellular exchange, pore formation, and protein binding, which are intimately related to cell functionality and effective pharmaceuticals. Therefore, understanding how these fluctuations are controlled can remarkably impact medical applications involving selective macromolecule binding and efficient cellular drug intake. Interestingly, previous reports on single-component bilayers show almost identical thickness fluctuation patterns for all investigated lipid tail-lengths, with similar temperature-independent membrane thickness fluctuation amplitude in the fluid phase and a rapid suppression of fluctuations upon transition to the gel phase. Presumably, in vivo functions require a tunability of these parameters, suggesting that more complex model systems are necessary. In this study, we explore lipid tail-length mismatch as a regulator for membrane fluctuations. Unilamellar vesicles of an equimolar mixture of dimyristoylphosphatidylcholine and distearoylphosphatidylcholine molecules, with different tail-lengths and melting transition temperatures, are used as a model system for this next level of complexity. Indeed, this binary system exhibits a significant response of membrane dynamics to thermal variations. The system also suggests a decoupling of the amplitude and the relaxation time of the membrane thickness fluctuations, implying a potential for independent control of these two key parameters.
authors.affiliation: National Institute of Standards and Technology (NIST) Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland; Department of Material Science and Engineering, University of Maryland, College Park, Maryland.
authors.forename: Rana
authors.initials: R
authors.lastname: Ashkar
authors.affiliation: National Institute of Standards and Technology (NIST) Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland; Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana. Electronic address: mnagao@indiana.edu.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Nagao
authors.affiliation: National Institute of Standards and Technology (NIST) Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland; Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Butler
authors.affiliation: Department of Chemistry & Life Science, United States Military Academy, West Point, New York.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Woodka
authors.affiliation: Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York.
authors.forename: Mani K
authors.initials: MK
authors.lastname: Sen
authors.affiliation: Department of Materials Science and Engineering, Stony Brook University, Stony Brook, New York; Chemical and Molecular Engineering Program, Stony Brook University, Stony Brook, New York.
authors.forename: Tadanori
authors.initials: T
authors.lastname: Koga
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008956:Models, Chemical; D033363:Neutron Diffraction; D010713:Phosphatidylcholines / Q000737:chemistry*; D053838:Scattering, Small Angle; D013057:Spectrum Analysis; D044366:Transition Temperature; D053835:Unilamellar Liposomes / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D053835:Unilamellar Liposomes; C010942:1,2-distearoyllecithin; D004134:Dimyristoylphosphatidylcholine