Single-molecule observation of anomalous electrohydrodynamic orientation of microtubules.
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, variantEL3, 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.
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
M G L
MG
van den Heuvel
R
R
Bondesan
M Cosentino
MC
Lagomarsino
C
C
Dekker
D004574:Electromagnetic Fields; D007700:Kinetics; D008856:Microscopy, Fluorescence / Q000379:methods; D008870:Microtubules / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure