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dc.contributor.authorAmmoor, Yamini Sravanthi
dc.date.accessioned2016-04-05T20:01:20Z
dc.date.available2016-04-05T20:01:20Z
dc.date.issued2015
dc.identifier.isbn9781321920475
dc.identifier.other1716383174
dc.identifier.urihttp://hdl.handle.net/10477/51846
dc.description.abstractThe membranes of viable cells are boundaries that control the transit of material into and out of the cell. Pivotal components of these membranes are bilayers of phospholipids with intercalated cholesterol, embedded membrane proteins and other constituents. The quantitative study of the permeability of phospholipid bilayers is key to understanding the permeation of various molecules through cell walls. Permeability depends on structural properties of these bilayers. This thesis presents a detailed study of the permeability coefficients of phospholipid bilayers in their gel phase with the aim of informing modelling effects in such areas as drug and chemical absorption through the stratum corneum (SC) layer of skin, and permeation of cryoprotectant molecules into erythrocytes in the freezing of blood. In both the cases, the operative temperature is below the gel-fluid transition temperature. The study addresses: (a) permeability coefficients of various solutes through the phospholipid bilayers; (b) the key structural properties that mostly strongly influence the permeability coefficients (i.e. lipid biophysics); and (c) the phase behavior of the pure phospholipids and phospholipids with cholesterol. The main motive for studying phase behavior is the need to know the conditions under which the bilayer is in the gel phase. The character of this investigation is a thorough compilation and assessment of data reported in the lipid biophysics and permeability literatures. It covers phosphatidylcholines broadly representative of viable cell membranes. * Permeability coefficient data for various phospholipids at different temperatures and cholesterol mole fractions are collected from the literature. The data show great variations among various solutes and phospholipids and are difficult to interpret as is. * Aspects of lipid biophysics are described in detail, particularly the area per phospholipids A , and the normalized surface density *. These parameters quantify the packing density of the fatty acid chains in the bilayer (i.e. the hydrophobic part), which determines the free volume available in the trans-bilayer diffusion process. The dependence of A and σ on temperature and cholesterol content are also discussed. * Changes in phase with changing temperature and cholesterol content are quantified in terms of phase diagrams for phospholipids. * Theoretical relationships are developed that make variations in permeability explicable when expressed in terms of a chain ordering factor following ideas of Xiang & Anderson. ( J. Membrane Biol. 148, 157-167 (1995) )
dc.languageEnglish
dc.sourceDissertations & Theses @ SUNY Buffalo,ProQuest Dissertations & Theses Global
dc.subjectPure sciences
dc.subjectApplied sciences
dc.subjectHealth and environmental sciences
dc.subjectCholesterol
dc.subjectGel-phase
dc.subjectLipid biophysics
dc.subjectPermeability
dc.subjectPhase behavior
dc.subjectPhospholipid bilayers
dc.titlePermeability of gel phase phospholipid bilayers
dc.typeDissertation/Thesis


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