We use fluorescence microscopy to measure the orientation and shape of microtubules-which serve as a model system for semiflexible rods-that are electrophoretically driven. Surprisingly, a bimodal orientation distribution is observed, with microtubules in either parallel or perpendicular orientations to the electric field. The occupancy of these states varies nonmonotonically with the microtubule length L and the electric field E. We also observe a surprising bending deformation of microtubules. Interestingly, all data collapse onto a universal scaling curve when the average alignment is plotted as a function of B proportional to EL3, which reflects the ratio between the driving force and a restoring elastic force. Our results have important implications for the interpretation of electrical birefringence experiments and, more generally, for a better understanding of the electrokinetics of rods.
|Titolo:||Single-molecule observation of anomalous electro-hydrodynamic orientation of microtubules|
|Autori interni:||COSENTINO LAGOMARSINO, MARCO (Penultimo)|
|Data di pubblicazione:||set-2008|
|Digital Object Identifier (DOI):||10.1103/PhysRevLett.101.118301|
|Appare nelle tipologie:||01 - Articolo su periodico|