Fullerenes in liquids

Fullerenes are a family of carbon allotropes, molecules composed entirely of carbon, which form hollow spheres, ellipsoids, tubes, or planes. Their unique physical properties make them excellent candidates for applications ranging from gas sensors to targeted drug design and delivery. We focus on the interaction of fullerenes with fluids as we are interested in the design of nanosensors and actuators. Of particular interest is the interaction of fullerenes with water and biomolecules for bio-nanotechnology applications.
 Water Droplet inside a CNT
Hydrophobic interactions of CNTs Water Transport in CNTs

Electrophoretic RNA transport through transmembrane carbon nanotubes
We use molecular  dynamics simulations to study the electrophoretic transport of RNA through carbon nanotubes embedded in membranes. Decorated and naked carbon nanotubes are inserted into a dodecane membrane and a dimyristoylphosphatidylcholine lipid bilayer, and the system is subjected to electrostatic potential differences. The transport properties of this artificial pore are determined by the structural modifications of the membrane in the vicinity of the nanotube openings and they are quantified by the nonuniform electrostatic potential maps at the entrance and inside the nanotube.
RNA transport through transmembrane carbon nanotube (top, side and cut view)

Carbon nanotubes as toxic gas  sensors

Recent experimental results have shown that carbon nanotube based sensors are promising transductors elements for gas sensors. The carbon nanotubes show both a high sensitivity to low  concentrations of nitrogen dioxide (NO2) as well as  low power consumption. In cooperation with the Micro and Nanosystems group we seek to better understand the mechanism with which Single Walled Carbon Nanotubes (SWCNT) react to the presence of nitrogen dioxide in a gas.
 
CNT device
CNT based NO2 sensing device, developed by Micro and Nanosystems Group.
MD simulations of a large CNT in NO2 gases
 

Computational Approach and Challenges

Using molecular dynamics  we simulated a SWCNT in a gas atmosphere composed of Oxygen, Nitrogen with ratios by mass of 80% and  20%. The experimental results show that the SWCNT reacts to the presence of NO2 in its vicinity with a time scale in the order of 100's of seconds. These time  scales are not reachable purely by Molecular Dynamics. Different multiscale approaches based on the experitise of the CSE lab  are being explored to bridge this gap of scales.


PeopleEvangelos KotsalisJens Honoré WaltherAlvaro Foletti

Collaborators: Professor C. Hieriold, Dr. R. Cosmin(ETHZ), Dr. Richard Jaffe (NASA Ames)

Publications
  • Zimmerli U., Koumoutsakos P., Simulations of Electrophoretic RNA Transport through Transmembrane Carbon Nanotubes, Biophysical J. , 94, 2008 (Abstract(pdf)
  • Kotsalis E. M., Demosthenous E., Walther J.H., Kassinos S. C., and Koumoutsakos P., Wetting of doped carbon nanotubes by water droplets. Chemical Physics Letters, 412(4-6):250-254, 2005 (Abstract) (pdf)
  • Kotsalis E. M., Walther J. H., Koumoutsakos P., Multiphase water flow inside carbon nanotubes, Int. J. Multiphase Flow, 30, 995-1010, 2004 (Abstract) (pdf)
  • Walther J. H., Jaffe R. L., Kotsalis E.  M., Werder T., Halicioglu T., and P. Koumoutsakos, Hydrophobic hydration of C60 and carbon nanotubes in water, Carbon, 42(5-6), 1185-1194, 2004 (Abstract) (pdf)
  • Werder T., Walther J. H., Jaffe R. L., Halicioglu T., and  P. Koumoutsakos, On the water-carbon interaction for use in MD simulations of graphite and carbon nanotubes, J. Phys. Chem. B., 107, 1345-1352, 2003 (Abstract) (pdf)
  • Walther J. H., Halicioglu T., Jaffe R., and Koumoutsakos P., Carbon nanotubes in water: structural characteristics and energetics, J. Phys. Chem. B., 105, 9980-9987, 2001 (Abstract) (pdf)