(749g) A Molecular Dynamics Study of Carbon-Based Nanoparticles Interacting with DOPC Bilayers: Emergent Behavior

With the advent of nanotechnology, the use of nanoparticles for biomedical and biological applications has immensely increased. The application of nanoparticles in such applications is invoking toxicological studies for the nanoparticles as they interact with living cells. However, a detailed understating of such macroscopic observations requires molecular-level investigations for capturing the molecular mechanisms responsible for the interaction of nanoparticles (we are particularly focused on carbon nanotubes) with living organisms. Along this research direction, we performed molecular dynamics studies involving nanoparticles confined within phospholipid bilayers. In this study we report structure and morphology of dioleoylphosphatidylcholine (DOPC) bilayers free-standing and in the presence of nanoparticles. The nanoparticles used were capped (5,5) single walled carbon nanotubes (SWNTs) and C60 fullerenes. We simulated two nanoparticles simultaneously present within one DOPC bilayer: (a) one C60 and one capped (5,5) SWNTs, and (b) two (5,5) SWNTs. The two nanoparticles within the DOPC bilayers were separated by either 5.0 or 1.0 nm. Then a third nanoparticle was simulated as it approaches the bilayer. Concerning the free-standing DOPC bilayer, our simulations were performed such that the area per DOPC molecules corresponds to the experimental value of ~0.70 nm2 per molecule. Umbrella sampling techniques, along with weighted histogram analysis method (WHAM) were employed to compute the PMF profiles for the nanoparticles along the direction perpendicular to the DOPC bilayer. The results will improve the understanding of the translocation of nanoparticle through the phospholipid bilayer (a simplified representation of cell membranes), as it is affected by emergent phenomena.