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CHARACTERIZATION, CONTROL AND MODELING OF PHASE SEPARATION IN MIXED PHOSPHOLIPID-PERFLUORINATED FATTY ACID MONOLAYERS

dc.contributor.advisorPaige, Matthew F.en_US
dc.contributor.committeeMemberUrquhart, Stephenen_US
dc.contributor.committeeMemberKaminskyj, Sueen_US
dc.contributor.committeeMemberPalmer, Daviden_US
dc.contributor.committeeMemberReid, Steveen_US
dc.creatorEftaiha, Alaen_US
dc.date.accessioned2013-05-29T12:00:14Z
dc.date.available2013-05-29T12:00:14Z
dc.date.created2013-05en_US
dc.date.issued2013-05-28en_US
dc.date.submittedMay 2013en_US
dc.description.abstractThe overall objective of this PhD thesis research is to understand and control phase separation in mixed perfluorinated fatty acid-phospholipid surfactant systems that have applications as pulmonary surfactant (PS) mixtures, with an ultimate view of controlling film composition, morphology and mechanical properties. In this context the interaction between perfluorooctadecanoic acid (C18F), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), the major component of native PS extract, and 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) has been explored in Langmuir monolayers and Langmuir–Blodgett (LB) films using a combination of atomic force microscopy (AFM), fluorescence microscopy (FM) and Brewster angle microscopy (BAM) measurements. Thermodynamic and morphological studies of binary and ternary mixed films made of C18F, DPPC and DPPG indicated that both the phospholipids and C18F were miscible over a wide range of compositions. The mixed phospholipid-C18F films contained multimolecular aggregates that were highly enriched in the phospholipids. Furthermore, it was found that the magnitude of the DPPC-C18F interaction could be modulated by altering the concentration of sodium ions in the underlying subphase. Using a highly simplified lung mimic fluid (pH 7.4, 150mM NaCl), DPPC and C18F became fully immiscible. Moreover, the performance characteristics of the mixed films demonstrated the usefulness of C18F as an additive for PS formulations. The effectiveness of a PS protein mimicking peptide was evaluated against DPPC to allow comparison with previous measurements of DPPC-C18F mixed system. The mixing thermodynamics of the peptide and DPPC in Langmuir monolayer implied a repulsive interaction between the film components. The hysteresis response of the mixed monolayer films indicated that the lipid-protein mixture improved the re-spreading of DPPC films. Moreover, molecular-level organization of the mixed films explored by both FM and BAM confirmed the formation of liquid-expanded DPPC domains in the presence of minute amount of the peptide. In order to obtain a thorough understanding of the effect of the deposition process and surfactant tail polarities on the interfacial behavior of perfluorocarbon-hydrocarbon mixed monolayer films, both BAM and AFM measurements of arachidic acid (C20) with perfluorotetradecanoic acid (C14F) and palmitic acid (C16) with C18F mixed monolayer were performed. These measurements revealed that film morphology was minimally perturbed upon its deposition onto solid substrates. Coarse grained molecular dynamics (MD) simulations of films comprised of DPPC molecules with tails of various polarities suggested that the phase separation between the monolayer components could be controlled by varying surfactant tail polarities.en_US
dc.identifier.urihttp://hdl.handle.net/10388/ETD-2013-05-1036en_US
dc.language.isoengen_US
dc.subjectPulmonary lung surfactanten_US
dc.subjectLangmuir monolayeren_US
dc.subjectMiscibilityen_US
dc.subjectPhase-separationen_US
dc.subjectDipalmitoyl phosphatidylcholineen_US
dc.subjectPerfluorooctadecanoic aciden_US
dc.subjectAtomic force microscopyen_US
dc.subjectFluorescence microscopyen_US
dc.subjectBrewster angle microscopyen_US
dc.subjectCoarse grained molecular dynamics simulationsen_US
dc.titleCHARACTERIZATION, CONTROL AND MODELING OF PHASE SEPARATION IN MIXED PHOSPHOLIPID-PERFLUORINATED FATTY ACID MONOLAYERSen_US
dc.type.genreThesisen_US
dc.type.materialtexten_US
thesis.degree.departmentChemistryen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophy (Ph.D.)en_US

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