1. “Transporting a Tube in a Tube”
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

2. 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.

3. 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.

4. (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)

5. Observation of the Tubes

6. 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

7. 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.

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

9. 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

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