Motility of CoFe 2 O 4 nanoparticle-labelled microtubules in magnetic fields

Kinesin motor proteins transport intracellular cargo unidirectionally along microtubule tracks. This intracellular transport system is being explored as a novel method of assembly, separation, and transport in nano- and micro-scale systems; however, facile techniques for patterning and directing microtubules remain limited. Biotinylated 20 nm diameter CoFe2O4 magnetic particles and neutravidin bridging molecules are used to label microtubules containing varying amounts of biotin. The effect of magnetic nanoparticle labelling on the speed of microtubule gliding across kinesin-covered surfaces is investigated both with and without applied magnetic fields. Microtubule gliding speed decreased with an increasing amount of attached magnetic cargo, but very lightly decorated microtubules were only slightly affected. All magnetically tagged microtubules could be drawn from the solution by application of a magnetic field, however, the presence of a field did not significantly affect gliding speed or direction. These findings provide new insight for the ultimate use of external magnetic fields as a tool to control the kinesin/microtubule system in carrying out concerted nanobiological tasks.