Brownian Motion of Stiff Filaments in a Crowded Environment

N. Fakhri, F.C. MacKintosh, B. Lounis, L. Cognet, M. Pasquali

Research output: Contribution to JournalArticleAcademicpeer-review


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.
Original languageEnglish
Pages (from-to)1804-1807
Issue number6012
Publication statusPublished - 2010


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