(749h) Lipid-Mediated Interactions Between Nanoparticles Embedded in Lipid Membranes

Understanding behavior of nanoparticles embedded in lipid membranes is important for the development of biomimetic devices and assessment of potentially harmful effects of nanomaterials on living cells. Nanoparticles embedded into a bilayer create an additional stress in the membrane interior. In order to minimize the stress, the nanoparticles may either repel or attract each other, depending on the specifics of their interactions with the surrounding lipids. The stress perturbation may propagate over large distances thus inducing long-range interactions between the nanoparticles. Attractive interactions are of particular interest, since in this case the nanoparticles may form large clusters which may significantly perturb the membrane structure and may lead to membrane destabilization. We perform molecular dynamics (MD) simulations to investigate the lipid-induced interactions between nanoparticles embedded into a dipalmitoylphosphatidylcholine (DPPC) lipid membrane. Two types of nanoparticles are considered, namely fullerenes and functionalized fullerenes (fullerenols). The former nanoparticles are hydrophobic, while the latter are amphiphilic, which suggests that their interaction with the membrane is likely to be substantially different. The results of MD simulations are compared with predictions of a harmonic model for membrane elastic properties. This model expresses the membrane energy and stress profiles as functions of the membrane shape and lipid tilt which are obtained by a variational approach. Validity of the harmonic approximation and possible improvements to the elastic model will be discussed.