Speaker
Dr
Jayne Wallace
(University of Oxford, UK)
Description
There is great interest in exploiting the novel properties
of carbon nanotubes (CNTs) for use in biology and medicine.
For example, CNTs have potential application in drug
delivery, cancer and gene therapy, and as components of
biosensors. However, prior to their usage we need to both
develop methods to overcome the hydrophobicity-induced
aggregation of CNTs, and also to understand the fundamental
interactions of CNTs with cellular components.
Dissolution of CNTs has been facilitated by the noncovalent
adsorption of both lipids and detergents onto the surface of
CNTs. We investigate the interaction of both lipids and
detergents with single-walled CNTs via coarse-grained
molecular dynamics [1,2]. We present evidence that the
mechanism of adsorption of these amphiphiles onto a CNT is
dependent upon amphiphile concentration. Furthermore, the
chirality of the CNT influences the amphiphile wrapping
angle for low amphiphile concentration.
Recently, designed synthetic peptides have also proven
effective at dispersing CNTs. This approach has the
significant advantage that the nature of the peptides
coating the CNTs can be controlled by specifying the amino
acid sequence. Hence, peptides can be designed such that the
peptide/CNT complex may target specific tissue. One such
designed synthetic peptide, nano-1 [3], folds into an
amphiphilic α-helix in the presence of CNTs and leads to CNT
dispersion. We implement molecular dynamics to investigate
the self-assembly of nano-1 onto CNTs, using both a
coarse-grained and atomistic approach. Using this
multi-scaled method, we show that nano-1 interacts with CNTs
in a preferential orientation. Furthermore, the charged
surfaces of nano-1 facilitate inter-peptide interactions
within the peptide/CNT complex, promoting helix stability.
We have also performed coarse-grained molecular dynamics
simulations of CNTs penetrating through lipid bilayers [4].
This work is motivated by the use of CNTs as nanoinjectors.
We show that CNTs extract lipids from the bilayer upon
penetration. These lipids interact with both the inner and
outer CNT surface, with lipids in the CNT interior
potentially “blocking” the tube.
[1] Wallace, E. J.; Sansom, M. S. P. Nano Lett. 2007, 7,
1923-1928.
[2] Wallace, E. J.; Sansom, M. S. P. Nanotechnology 2009,
20, 045101.
[3] Dieckmann, G. R.; Dalton, A. B.; Johnson, P. A.; Razal,
J.; Chen, J.; Giordano, G. M.; Munoz, E.; Musselman, I. H.;
Baughman, R. H.; Draper, R. K. J. Am. Chem. Soc. 2003, 125,
1770-1777.
[4] Wallace, E. J.; Sansom, M. S. P. Nano Lett. 2008, 8,
2751-2756.
Primary author
Dr
Jayne Wallace
(University of Oxford, UK)
