title: Simultaneous and bidirectional transport of kinesin-coated microspheres and dynein-coated microspheres on polarity-oriented microtubules.
abstract: Artificial nanotransport systems inspired by intracellular transport processes have been investigated for over a decade using the motor protein kinesin and microtubules. However, only unidirectional cargo transport has been achieved for the purpose of nanotransport in a microfluidic system. Here, we demonstrate bidirectional nanotransport by integrating kinesin and dynein motor proteins. Our molecular system allows microtubule orientation of either polarity in a microfluidic channel to construct a transport track. Each motor protein acts as a nanoactuators that transports microspheres in opposite directions determined by the polarity of the oriented microtubules: kinesin-coated microspheres move toward the plus end of microtubules, whereas dynein-coated microspheres move toward the minus end. We demonstrate both unidirectional and bidirectional transport using kinesin- and dynein-coated microspheres on microtubules oriented and glutaraldehyde-immobilized in a microfluidic channel. Tracking and statistical analysis of microsphere movement demonstrate that 87-98% of microspheres move in the designated direction at a mean velocity of 0.22-0.28 microm/s for kinesin-coated microspheres and 0.34-0.39 microm/s for dynein-coated microspheres. This bidirectional nanotransport goes beyond conventional unidirectional transport to achieve more complex artificial nanotransport in vitro.
authors.affiliation: Department of Micro System Technology, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan. ryuji@se.ritsumei.ac.jp
authors.forename: Ryuji
authors.initials: R
authors.lastname: Yokokawa
authors.forename: Mehmet Cagatay
authors.initials: MC
authors.lastname: Tarhan
authors.forename: Takahide
authors.initials: T
authors.lastname: Kon
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujita
mesh_terms: D000327:Adsorption; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D004398:Dyneins / Q000737:chemistry* / Q000648:ultrastructure; D016547:Kinesins / Q000737:chemistry* / Q000648:ultrastructure; D008422:Materials Testing; D008863:Microspheres; D008968:Molecular Conformation; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000648:ultrastructure; D009038:Motion; D011485:Protein Binding; D055672:Static Electricity
chemical_list: D020099:Coated Materials, Biocompatible; D020409:Molecular Motor Proteins; D004398:Dyneins; D016547:Kinesins