Platform BE: Multiscale Modeling of Biomolecular Systems

2571-Plat

Interactions between carbon nanoparticles and lipid bilayers: insights from MD simulations with a coarse-grained model

Wednesday, Mar 07, 2007, 8:45 AM -

Room 314/315

8E Molecular Dynamics

Luca Monticelli¹, Jirasak Wong-Ekkabut², Svetlana Baoukina¹, D. Peter Tieleman¹.
¹University of Calgary, Calgary, AB, Canada, ²Mahidol University, Bangkok, Thailand.

539a

Carbon nanoparticles are toxic and can enter the human body by penetrating biological membranes. In order to gain insight into the toxicology of nano-sized particle it is important to understand how these materials enter biological membranes. We used computer simulations to investigate the molecular interactions between carbon nanoparticles and membrane models.
Processes like the penetration of nanoparticles into lipid membranes involve crossing significant energy barriers and are therefore likely to take place on time scales that are relatively long for computer simulations. In order to overcome this problem, we developed coarse-grained (CG) models of simple carbon nanoparticles (fullerenes and nanotubes) compatible with the CG model for lipids and surfactants by Marrink et al. (J. Phys. Chem. B, 2004, 108, 750-760). Our CG models reproduce reasonably well the mechanical properties of carbon nanoparticles.
We used unbiased MD simulations to investigate the mechanism of penetration of the nanoparticles in a 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) bilayer. Smaller particles enter lipid bilayers more easily and rapidly. We used the umbrella sampling technique to calculate the potential of mean force as a function of distance from the lipid bilayer. The free energy profiles depend on the size and shape of the particles. Smaller particles have a smaller free energy barrier for entering the lipid bilayer and a higher free energy difference between bulk water and the bilayer interior. Larger particles have a higher barrier for entering the bilayer and a smaller energy difference between bulk water and the bilayer interior, due mainly to stronger perturbations in the structure of the model membrane. We also performed simulations of the aggregation of nanoparticles in water and inside a DOPC bilayer.

 L. Monticelli, None; J. Wong-Ekkabut, None; S. Baoukina, None; D.P. Tieleman, None.