Self-assembly Modeling of Biological Membranes by Dissipative Particle Dynamics Method

In this study, binary fluids consisting of ‘‘solvent’’ and ‘‘surfactant’’ molecules are studied as simplified model systems. Solutions of lipids in water are characterized by a wide range of length scales. Molecular Dynamics (MD) technique is used to study equilibrium and transport properties of biological membranes. However, classical molecular dynamics can deal with hundreds of thousands of atoms over a timescale of the order of 100 ns. For larger time and length scales the MD simulation becomes extremely expensive or even impossible. Recently, Dissipative Particle Dynamics (DPD) has been introduced as a mesoscopic simulation method that enables us to apply length and time scales that are significantly larger (several order of magnitude) than the one used in conventional MD simulations. The aim of this study is to simulate the self-assembly of the surfactant molecules into bilayer membranes by the DPD method. Our simulations verify that by using a periodic boundary condition and a fixed number of surfactants per area, a bilayer is formed which has a specific value of surface tension. Moreover, the surfactant consists of a hydrophilic head group and a hydrophobic tail group which was modeled by chains of particles interconnected by a harmonic bond potential. In this study the bending stiffness of these chains were incorporated. We were able to give to our surfactants a specific chemical structure and therefore, our membrane simulation result is closer to the physics. This makes our work quite distinct from most of previous studies. Eventually the effect of changes in the chain length and stiffness of the surfactants on the properties of the modeled membranes were studied. We observed that depending on the location of stiffness applied, the stiffness of chains have significant effect on the surfactant properties.

کلیدواژه ها:

Dpd ، Biological Membrane ، Lipid Bilayer