“Transporting a Tube in a Tube” 11. 8. 2015 Paper Introduction “Transporting a Tube in a Tube” J. Li, Y. Jia,* W. Dong, X. Feng, J. Fei, and J. Li* Nano Lett. 2014, 14, 6160. Yoshimitsu Sagara

A Drawback of the Present Motility Assay Well-established microtubule-kinesin system in vitro microtubule ATP-driven unidirectional movement Kinesin Nice candidates of nano-device to transport small cargos Complete on/off switching with light irradiation Drawback Each microtubule moves in random directions. ACS Nano 2014, 8, 4157.

Some Approaches to Solve the Problem Photolithographic tracks Electric field A. Sikora et al., Nano Lett. 2014, 14, 876. Y. Hiratsuka et al., Biophys. J. 2001, 81, 1555. Magnetic field Employing linear tubes M. Lard et al., Nano Lett. 2014, 14, 876. B. M. Hutchins et al., Small 2007, 3, 126.

(poly(allylamine hydrochloride)) (dextran sulfate sodium) Today’s Paper “Transporting a Tube in a Tube” J. Li, Y. Jia,* W. Dong, X. Feng, J. Fei, and J. Li* Nano Lett. 2014, 14, 6160. diameter: 3 μm, thickness: 23 μm PAH (poly(allylamine hydrochloride)) (labelled with FITC) DSS (dextran sulfate sodium)

Observation of the Tubes

How to Immobilize Kinesins in the Tubes For immobilization of kinesins, the Ni−NTA (nitrilotriacetic acid) complex was chosen. The authors modified the tube inner walls with the Ni−NTA complex by assembling the NH2−NTA (Nα,Nα-bis-(carboxymethyl)-L-lysine hydrate)-modified sodium alginate (ALG) (denoted as ALG−NTA) as the innermost layer of the tubes after 29.5 times deposition cycles. After deposition of Ni+, the membrane was treated with oxygen plasma to remove undesired adsorbed films. the His-tagged C-terminal of kinesin

Confirmation of introduction of kinesins Labeled with Alexa Flour 647-maleimide Confocal fluorescent microscopic images of the assembled tubes with different treatment: a) pure tube; b) non-functionalized tube treated with fluorescent labeled kinesin; d) Ni-NTA modified tube that was treated with fluorescent labeled kinesin.

Motility Assay in the Tubes The mean gliding speed is 0.61 μm S-1.

Cargos Passing through the Tubes The authors also show that the LbL-tubes work as a guide for cargo transportation. Streptavidin-modified magnetic polystyrene attached to the microtubules

Summary The authors succeeded in utilizing inner spaces of LbL-tubes as guides for the microtubules’s gliding. The observed gliding speed was ca. 0.61 μm S-1 The authors also show that the LbL-tubes work as a guide for cargo transportation.