title: Brownian motion of stiff filaments in a crowded environment.
abstract: The thermal motion of stiff filaments in a crowded environment is highly constrained and anisotropic; it underlies the behavior of such disparate systems as polymer materials, nanocomposites, and the cell cytoskeleton. Despite decades of theoretical study, the fundamental dynamics of such systems remains a mystery. Using near-infrared video microscopy, we studied the thermal diffusion of individual single-walled carbon nanotubes (SWNTs) confined in porous agarose networks. We found that even a small bending flexibility of SWNTs strongly enhances their motion: The rotational diffusion constant is proportional to the filament-bending compliance and is independent of the network pore size. The interplay between crowding and thermal bending implies that the notion of a filament's stiffness depends on its confinement. Moreover, the mobility of SWNTs and other inclusions can be controlled by tailoring their stiffness.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX 77005, USA.
authors.forename: Nikta
authors.initials: N
authors.lastname: Fakhri
authors.forename: Frederick C
authors.initials: FC
authors.lastname: MacKintosh
authors.forename: Brahim
authors.initials: B
authors.lastname: Lounis
authors.forename: Laurent
authors.initials: L
authors.lastname: Cognet
authors.forename: Matteo
authors.initials: M
authors.lastname: Pasquali
mesh_terms: D055598:Chemical Phenomena; D004058:Diffusion; D018715:Microscopy, Video; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012685:Sepharose; D013696:Temperature
chemical_list: D037742:Nanotubes, Carbon; D011108:Polymers; D012685:Sepharose