(125b) Elastic Properties of Lipid Bilayers Containing Embedded Nanoparticles

In this talk, we discuss interactions between lipid membranes and nanoparticles. Understanding these interactions is important for development of biomimetic devices and assessment of potentially harmful effects of nanomaterials on living cells. We use molecular dynamics simulations to assess changes of elastic properties of a lipid membrane in response to embedding nanoparticles into the membrane. The considered elastic properties include the membrane bending and tilt moduli, as well as the lateral pressure profile inside the membrane. The studies are performed using a coarse-grained molecular dynamics model, which represents groups of several atoms as united atoms (beads). The considered bilayer is composed of Dipalmitoylphosphatidylcholine (DPPC) lipids. Several coarse-grained models for nanoparticles are considered in order to mimic carbon-based nanoparticles of different shapes and sizes. The considered nanoparticles are hydrophobic and therefore they reside in the interior of the bilayer. It is observed that the membrane bending modulus remains constant at moderate concentrations of nanoparticles within the bilayer. Moreover, the tilt fluctuations of the lipid molecules are affected only in the direct neighborhood of the nanoparticles. In contrast, the lateral pressure profiles change significantly upon embedding of the nanoparticles. We develop a theoretical model to explain the changes of the pressure profiles in the presence of the nanoparticles and discuss possible implication of the altered pressure profile on biophysical processes in cellular membranes.