Evaluating Mechanical Properties of Bilayer Membranes Using Dissipative Particle Dynamics

Membrane deformability plays a crucial role in many functions that a live cell performs. Elastic properties, such as bending modulus, is a function of the bilayer composition, membrane thickness and temperature of the system. Theoretical studies suggest that the bending modulus κ~d ^p, where d is the membrane thickness and the exponent p is between 2-3. In the present work, dissipative particle dynamics (DPD) is used to obtain the bending modulus as a function of membrane thickness. Our study shows that the soft repulsive bead representation in a DPD model accurately captures the scaling of the bending modulus, κ as a function of the membrane thickness. Using the same method, we have also investigated the bending modulus of the lipid bilayers in the low temperature gel (L_β) phase. Depending on the chain length, the bending modulus in the gel phase is about 9 to 16 times larger than that observed for the liquid crystalline (L_α) phase. This increase in the bending modulus for the gel phase is in the range of experimentally observed changes during gel to the liquid crystalline phase transition.