Molecular simulation of mixtures in lipid bilayers
- Autores: Adrien Berthault
- Directores de la Tesis: Vladimir Baulin (dir. tes.)
- Lectura: En la Universitat Rovira i Virgili ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: Jean Baptiste Fleury (presid.), Josep Bonet Avalos (secret.), José Luis Chiara Romero (voc.)
- Programa de doctorado: Programa de Doctorado en Nanociencia, Materiales e Ingeniería Química por la Universidad Rovira i Virgili
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Lipid membranes have a major role in the defence of cells and their regulation processes with the external medium. Poorly understood because of their complexity, studies throughout years already brought hints which help to comprehend them and develop direct applications. This work presents an extension of a fast and reliable method (Single Chain Mean Field (SCMF)) to study mixtures at equilibrium and in particular mixtures of lipids and small colloids inserted into lipid membranes, able to consider the presence of additional components and bridge molecular simulation models and elastic theories for amphiphilic membranes. During this work, we focused on the parametrisation of the parameters for the SCMF method to reproduce the features of DMPC lipid bilayers at equilibrium involving comparisons with previously published simulation results and experimental data. The thesis reports the work performed to achieve the specific objectives of this doctoral thesis: reliable fully parametrised molecular details able to reproduce the behaviour of lipid membranes made of a single type of component, the study of their equilibrium properties interacting with additional molecules and their effects on the line tension for the specific case of the pore creation and a dynamical approach to study the dynamics of membranes made of various amphiphilic chains, in particular in the presence of pores. A general historical introduction showing scientific research interest in lipid membranes investigation is presented in Chapter I. Characterisation of amphiphilic membranes are obtained using the Single Chain Mean Field (SCMF) theory, designed to study systems at equilibrium. Combining it with the Helfrich model, we bridge the gap between analytical models and simulation methods in Chapter II. After establishing and verifying with experimental results the line tension of a pore formed with our DMPC model membrane system, a fully hydrophobic second molecule is studied. Various effects including line tension modification and membrane compressibility are observed and reported in Chapter III. To understand the behaviour of pores created in a bilayer made of two amphiphilic chains differing in their length, dynamical studies were performed with the Bond Fluctuation Model (BFM) and presented in Chapter IV. Finally, the last chapter shows general conclusions of the work carried in this thesis.
