Estudo computacional da eletroporação de membranas lipídicas

• Ano de defesa: 2016
• Autor(a) principal: Figueiredo, Jacieli Evangelho de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; Física; UFSM; Programa de Pós-Graduação em Física; Centro de Ciências Naturais e Exatas
• Palavras-chave em Português: Fosfolipídios; Campo elétrico; Poro; Phospholipid; Electric field; Pore; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: http://repositorio.ufsm.br/handle/1/12164

In this work we present a computational study of the electroporation process of lipid membranes in the presence of water. First, we developed an investigation of the formation of pores through simulations based on classical molecular dynamics using NAMD code. Subsequently we developed ab initio study using density functional theory, as implemented in the SIESTA code. This analysis showed the formation of pores within the lipid bilayer 1ns after the application of external electric field, 300 K. We found that set temperatures above 300 K may reduce the simulation time. We also observed a rearrangement of water molecules of a Okuno Tanioka cone due to the action of the electric field. Interestingly, this induced an increase of the number of hydrogen bonds, which was not observed using apolar molecules such as chloroform. After, we performed the analysis of structural and electronic properties of the structures of phospholipids,which were extracted from the molecular dynamics calculations. It is noteworthy that the action of the electric field changed the energy gap of both the structures of isolated phospholipid as for the lipid bilayer configuration. Through maps of electrostatic potential, we showed that the electric field leads to a polarization of phospholipid, which induced a torque in the electric dipole moments of the water molecule. The rotation of the electric dipole moments gave rise to stress in the lipid bilayer, which by itself was not enough to break it. In summary, the presence of water was critical since under the action of an electric field the molecules rearranged to form a cone. This fact, associated with the weakening of the lipid membrane due the stress from the realignment electric dipole, was the responsible for the poration process.